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linux_old1/kernel/locking/lockdep.c

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/*
* kernel/lockdep.c
*
* Runtime locking correctness validator
*
* Started by Ingo Molnar:
*
* Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
* Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
*
* this code maps all the lock dependencies as they occur in a live kernel
* and will warn about the following classes of locking bugs:
*
* - lock inversion scenarios
* - circular lock dependencies
* - hardirq/softirq safe/unsafe locking bugs
*
* Bugs are reported even if the current locking scenario does not cause
* any deadlock at this point.
*
* I.e. if anytime in the past two locks were taken in a different order,
* even if it happened for another task, even if those were different
* locks (but of the same class as this lock), this code will detect it.
*
* Thanks to Arjan van de Ven for coming up with the initial idea of
* mapping lock dependencies runtime.
*/
#define DISABLE_BRANCH_PROFILING
#include <linux/mutex.h>
#include <linux/sched.h>
#include <linux/sched/clock.h>
#include <linux/sched/task.h>
#include <linux/sched/mm.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/spinlock.h>
#include <linux/kallsyms.h>
#include <linux/interrupt.h>
#include <linux/stacktrace.h>
#include <linux/debug_locks.h>
#include <linux/irqflags.h>
#include <linux/utsname.h>
#include <linux/hash.h>
#include <linux/ftrace.h>
#include <linux/stringify.h>
#include <linux/bitmap.h>
#include <linux/bitops.h>
#include <linux/gfp.h>
#include <linux/random.h>
#include <linux/jhash.h>
#include <linux/nmi.h>
#include <linux/rcupdate.h>
#include <linux/kprobes.h>
#include <asm/sections.h>
#include "lockdep_internals.h"
#define CREATE_TRACE_POINTS
#include <trace/events/lock.h>
#ifdef CONFIG_PROVE_LOCKING
int prove_locking = 1;
module_param(prove_locking, int, 0644);
#else
#define prove_locking 0
#endif
#ifdef CONFIG_LOCK_STAT
int lock_stat = 1;
module_param(lock_stat, int, 0644);
#else
#define lock_stat 0
#endif
/*
* lockdep_lock: protects the lockdep graph, the hashes and the
* class/list/hash allocators.
*
* This is one of the rare exceptions where it's justified
* to use a raw spinlock - we really dont want the spinlock
* code to recurse back into the lockdep code...
*/
static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
static struct task_struct *lockdep_selftest_task_struct;
static int graph_lock(void)
{
arch_spin_lock(&lockdep_lock);
/*
* Make sure that if another CPU detected a bug while
* walking the graph we dont change it (while the other
* CPU is busy printing out stuff with the graph lock
* dropped already)
*/
if (!debug_locks) {
arch_spin_unlock(&lockdep_lock);
return 0;
}
/* prevent any recursions within lockdep from causing deadlocks */
current->lockdep_recursion++;
return 1;
}
static inline int graph_unlock(void)
{
if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
/*
* The lockdep graph lock isn't locked while we expect it to
* be, we're confused now, bye!
*/
return DEBUG_LOCKS_WARN_ON(1);
}
current->lockdep_recursion--;
arch_spin_unlock(&lockdep_lock);
return 0;
}
/*
* Turn lock debugging off and return with 0 if it was off already,
* and also release the graph lock:
*/
static inline int debug_locks_off_graph_unlock(void)
{
int ret = debug_locks_off();
arch_spin_unlock(&lockdep_lock);
return ret;
}
unsigned long nr_list_entries;
static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
static DECLARE_BITMAP(list_entries_in_use, MAX_LOCKDEP_ENTRIES);
/*
* All data structures here are protected by the global debug_lock.
*
* nr_lock_classes is the number of elements of lock_classes[] that is
* in use.
*/
#define KEYHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
#define KEYHASH_SIZE (1UL << KEYHASH_BITS)
static struct hlist_head lock_keys_hash[KEYHASH_SIZE];
unsigned long nr_lock_classes;
#ifndef CONFIG_DEBUG_LOCKDEP
static
#endif
struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
static inline struct lock_class *hlock_class(struct held_lock *hlock)
{
if (!hlock->class_idx) {
/*
* Someone passed in garbage, we give up.
*/
DEBUG_LOCKS_WARN_ON(1);
return NULL;
}
return lock_classes + hlock->class_idx - 1;
}
#ifdef CONFIG_LOCK_STAT
static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats);
static inline u64 lockstat_clock(void)
{
return local_clock();
}
static int lock_point(unsigned long points[], unsigned long ip)
{
int i;
for (i = 0; i < LOCKSTAT_POINTS; i++) {
if (points[i] == 0) {
points[i] = ip;
break;
}
if (points[i] == ip)
break;
}
return i;
}
static void lock_time_inc(struct lock_time *lt, u64 time)
{
if (time > lt->max)
lt->max = time;
if (time < lt->min || !lt->nr)
lt->min = time;
lt->total += time;
lt->nr++;
}
static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
{
if (!src->nr)
return;
if (src->max > dst->max)
dst->max = src->max;
if (src->min < dst->min || !dst->nr)
dst->min = src->min;
dst->total += src->total;
dst->nr += src->nr;
}
struct lock_class_stats lock_stats(struct lock_class *class)
{
struct lock_class_stats stats;
int cpu, i;
memset(&stats, 0, sizeof(struct lock_class_stats));
for_each_possible_cpu(cpu) {
struct lock_class_stats *pcs =
&per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
stats.contention_point[i] += pcs->contention_point[i];
for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
stats.contending_point[i] += pcs->contending_point[i];
lock_time_add(&pcs->read_waittime, &stats.read_waittime);
lock_time_add(&pcs->write_waittime, &stats.write_waittime);
lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
stats.bounces[i] += pcs->bounces[i];
}
return stats;
}
void clear_lock_stats(struct lock_class *class)
{
int cpu;
for_each_possible_cpu(cpu) {
struct lock_class_stats *cpu_stats =
&per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
memset(cpu_stats, 0, sizeof(struct lock_class_stats));
}
memset(class->contention_point, 0, sizeof(class->contention_point));
memset(class->contending_point, 0, sizeof(class->contending_point));
}
static struct lock_class_stats *get_lock_stats(struct lock_class *class)
{
return &this_cpu_ptr(cpu_lock_stats)[class - lock_classes];
}
static void lock_release_holdtime(struct held_lock *hlock)
{
struct lock_class_stats *stats;
u64 holdtime;
if (!lock_stat)
return;
holdtime = lockstat_clock() - hlock->holdtime_stamp;
stats = get_lock_stats(hlock_class(hlock));
if (hlock->read)
lock_time_inc(&stats->read_holdtime, holdtime);
else
lock_time_inc(&stats->write_holdtime, holdtime);
}
#else
static inline void lock_release_holdtime(struct held_lock *hlock)
{
}
#endif
/*
* We keep a global list of all lock classes. The list is only accessed with
* the lockdep spinlock lock held. free_lock_classes is a list with free
* elements. These elements are linked together by the lock_entry member in
* struct lock_class.
*/
LIST_HEAD(all_lock_classes);
static LIST_HEAD(free_lock_classes);
/**
* struct pending_free - information about data structures about to be freed
* @zapped: Head of a list with struct lock_class elements.
* @lock_chains_being_freed: Bitmap that indicates which lock_chains[] elements
* are about to be freed.
*/
struct pending_free {
struct list_head zapped;
DECLARE_BITMAP(lock_chains_being_freed, MAX_LOCKDEP_CHAINS);
};
/**
* struct delayed_free - data structures used for delayed freeing
*
* A data structure for delayed freeing of data structures that may be
* accessed by RCU readers at the time these were freed.
*
* @rcu_head: Used to schedule an RCU callback for freeing data structures.
* @index: Index of @pf to which freed data structures are added.
* @scheduled: Whether or not an RCU callback has been scheduled.
* @pf: Array with information about data structures about to be freed.
*/
static struct delayed_free {
struct rcu_head rcu_head;
int index;
int scheduled;
struct pending_free pf[2];
} delayed_free;
/*
* The lockdep classes are in a hash-table as well, for fast lookup:
*/
#define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
#define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
#define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
#define classhashentry(key) (classhash_table + __classhashfn((key)))
static struct hlist_head classhash_table[CLASSHASH_SIZE];
/*
* We put the lock dependency chains into a hash-table as well, to cache
* their existence:
*/
#define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
#define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
#define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
#define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
static struct hlist_head chainhash_table[CHAINHASH_SIZE];
/*
* The hash key of the lock dependency chains is a hash itself too:
* it's a hash of all locks taken up to that lock, including that lock.
* It's a 64-bit hash, because it's important for the keys to be
* unique.
*/
static inline u64 iterate_chain_key(u64 key, u32 idx)
{
u32 k0 = key, k1 = key >> 32;
__jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */
return k0 | (u64)k1 << 32;
}
void lockdep_off(void)
{
current->lockdep_recursion++;
}
EXPORT_SYMBOL(lockdep_off);
void lockdep_on(void)
{
current->lockdep_recursion--;
}
EXPORT_SYMBOL(lockdep_on);
void lockdep_set_selftest_task(struct task_struct *task)
{
lockdep_selftest_task_struct = task;
}
/*
* Debugging switches:
*/
#define VERBOSE 0
#define VERY_VERBOSE 0
#if VERBOSE
# define HARDIRQ_VERBOSE 1
# define SOFTIRQ_VERBOSE 1
#else
# define HARDIRQ_VERBOSE 0
# define SOFTIRQ_VERBOSE 0
#endif
#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
/*
* Quick filtering for interesting events:
*/
static int class_filter(struct lock_class *class)
{
#if 0
/* Example */
if (class->name_version == 1 &&
!strcmp(class->name, "lockname"))
return 1;
if (class->name_version == 1 &&
!strcmp(class->name, "&struct->lockfield"))
return 1;
#endif
/* Filter everything else. 1 would be to allow everything else */
return 0;
}
#endif
static int verbose(struct lock_class *class)
{
#if VERBOSE
return class_filter(class);
#endif
return 0;
}
/*
* Stack-trace: tightly packed array of stack backtrace
* addresses. Protected by the graph_lock.
*/
unsigned long nr_stack_trace_entries;
static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
static void print_lockdep_off(const char *bug_msg)
{
printk(KERN_DEBUG "%s\n", bug_msg);
printk(KERN_DEBUG "turning off the locking correctness validator.\n");
#ifdef CONFIG_LOCK_STAT
printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
#endif
}
static int save_trace(struct lock_trace *trace)
{
unsigned long *entries = stack_trace + nr_stack_trace_entries;
unsigned int max_entries;
trace->offset = nr_stack_trace_entries;
max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
trace->nr_entries = stack_trace_save(entries, max_entries, 3);
nr_stack_trace_entries += trace->nr_entries;
if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
if (!debug_locks_off_graph_unlock())
return 0;
print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
dump_stack();
return 0;
}
return 1;
}
unsigned int nr_hardirq_chains;
unsigned int nr_softirq_chains;
unsigned int nr_process_chains;
unsigned int max_lockdep_depth;
#ifdef CONFIG_DEBUG_LOCKDEP
/*
* Various lockdep statistics:
*/
DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
#endif
/*
* Locking printouts:
*/
#define __USAGE(__STATE) \
[LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
[LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
[LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
[LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
static const char *usage_str[] =
{
#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
#include "lockdep_states.h"
#undef LOCKDEP_STATE
[LOCK_USED] = "INITIAL USE",
};
const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
{
return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
}
static inline unsigned long lock_flag(enum lock_usage_bit bit)
{
return 1UL << bit;
}
static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
{
char c = '.';
if (class->usage_mask & lock_flag(bit + LOCK_USAGE_DIR_MASK))
c = '+';
if (class->usage_mask & lock_flag(bit)) {
c = '-';
if (class->usage_mask & lock_flag(bit + LOCK_USAGE_DIR_MASK))
c = '?';
}
return c;
}
void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
{
int i = 0;
#define LOCKDEP_STATE(__STATE) \
usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
#include "lockdep_states.h"
#undef LOCKDEP_STATE
usage[i] = '\0';
}
static void __print_lock_name(struct lock_class *class)
{
char str[KSYM_NAME_LEN];
const char *name;
name = class->name;
if (!name) {
name = __get_key_name(class->key, str);
printk(KERN_CONT "%s", name);
} else {
printk(KERN_CONT "%s", name);
if (class->name_version > 1)
printk(KERN_CONT "#%d", class->name_version);
if (class->subclass)
printk(KERN_CONT "/%d", class->subclass);
}
}
static void print_lock_name(struct lock_class *class)
{
char usage[LOCK_USAGE_CHARS];
get_usage_chars(class, usage);
printk(KERN_CONT " (");
__print_lock_name(class);
printk(KERN_CONT "){%s}", usage);
}
static void print_lockdep_cache(struct lockdep_map *lock)
{
const char *name;
char str[KSYM_NAME_LEN];
name = lock->name;
if (!name)
name = __get_key_name(lock->key->subkeys, str);
printk(KERN_CONT "%s", name);
}
static void print_lock(struct held_lock *hlock)
{
/*
* We can be called locklessly through debug_show_all_locks() so be
* extra careful, the hlock might have been released and cleared.
*/
unsigned int class_idx = hlock->class_idx;
/* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */
barrier();
if (!class_idx || (class_idx - 1) >= MAX_LOCKDEP_KEYS) {
printk(KERN_CONT "<RELEASED>\n");
return;
}
printk(KERN_CONT "%p", hlock->instance);
print_lock_name(lock_classes + class_idx - 1);
printk(KERN_CONT ", at: %pS\n", (void *)hlock->acquire_ip);
}
static void lockdep_print_held_locks(struct task_struct *p)
{
int i, depth = READ_ONCE(p->lockdep_depth);
if (!depth)
printk("no locks held by %s/%d.\n", p->comm, task_pid_nr(p));
else
printk("%d lock%s held by %s/%d:\n", depth,
depth > 1 ? "s" : "", p->comm, task_pid_nr(p));
/*
* It's not reliable to print a task's held locks if it's not sleeping
* and it's not the current task.
*/
if (p->state == TASK_RUNNING && p != current)
return;
for (i = 0; i < depth; i++) {
printk(" #%d: ", i);
print_lock(p->held_locks + i);
}
}
static void print_kernel_ident(void)
{
printk("%s %.*s %s\n", init_utsname()->release,
(int)strcspn(init_utsname()->version, " "),
init_utsname()->version,
print_tainted());
}
static int very_verbose(struct lock_class *class)
{
#if VERY_VERBOSE
return class_filter(class);
#endif
return 0;
}
/*
* Is this the address of a static object:
*/
#ifdef __KERNEL__
static int static_obj(const void *obj)
{
unsigned long start = (unsigned long) &_stext,
end = (unsigned long) &_end,
addr = (unsigned long) obj;
if (arch_is_kernel_initmem_freed(addr))
return 0;
/*
* static variable?
*/
if ((addr >= start) && (addr < end))
return 1;
if (arch_is_kernel_data(addr))
return 1;
/*
* in-kernel percpu var?
*/
if (is_kernel_percpu_address(addr))
return 1;
/*
* module static or percpu var?
*/
return is_module_address(addr) || is_module_percpu_address(addr);
}
#endif
/*
* To make lock name printouts unique, we calculate a unique
* class->name_version generation counter. The caller must hold the graph
* lock.
*/
static int count_matching_names(struct lock_class *new_class)
{
struct lock_class *class;
int count = 0;
if (!new_class->name)
return 0;
list_for_each_entry(class, &all_lock_classes, lock_entry) {
if (new_class->key - new_class->subclass == class->key)
return class->name_version;
if (class->name && !strcmp(class->name, new_class->name))
count = max(count, class->name_version);
}
return count + 1;
}
static inline struct lock_class *
look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass)
{
struct lockdep_subclass_key *key;
struct hlist_head *hash_head;
struct lock_class *class;
if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
debug_locks_off();
printk(KERN_ERR
"BUG: looking up invalid subclass: %u\n", subclass);
printk(KERN_ERR
"turning off the locking correctness validator.\n");
dump_stack();
return NULL;
}
/*
* If it is not initialised then it has never been locked,
* so it won't be present in the hash table.
*/
if (unlikely(!lock->key))
return NULL;
/*
* NOTE: the class-key must be unique. For dynamic locks, a static
* lock_class_key variable is passed in through the mutex_init()
* (or spin_lock_init()) call - which acts as the key. For static
* locks we use the lock object itself as the key.
*/
BUILD_BUG_ON(sizeof(struct lock_class_key) >
sizeof(struct lockdep_map));
key = lock->key->subkeys + subclass;
hash_head = classhashentry(key);
/*
* We do an RCU walk of the hash, see lockdep_free_key_range().
*/
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
return NULL;
hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
if (class->key == key) {
/*
* Huh! same key, different name? Did someone trample
* on some memory? We're most confused.
*/
WARN_ON_ONCE(class->name != lock->name);
return class;
}
}
return NULL;
}
/*
* Static locks do not have their class-keys yet - for them the key is
* the lock object itself. If the lock is in the per cpu area, the
* canonical address of the lock (per cpu offset removed) is used.
*/
static bool assign_lock_key(struct lockdep_map *lock)
{
unsigned long can_addr, addr = (unsigned long)lock;
#ifdef __KERNEL__
/*
* lockdep_free_key_range() assumes that struct lock_class_key
* objects do not overlap. Since we use the address of lock
* objects as class key for static objects, check whether the
* size of lock_class_key objects does not exceed the size of
* the smallest lock object.
*/
BUILD_BUG_ON(sizeof(struct lock_class_key) > sizeof(raw_spinlock_t));
#endif
if (__is_kernel_percpu_address(addr, &can_addr))
lock->key = (void *)can_addr;
else if (__is_module_percpu_address(addr, &can_addr))
lock->key = (void *)can_addr;
else if (static_obj(lock))
lock->key = (void *)lock;
else {
/* Debug-check: all keys must be persistent! */
debug_locks_off();
pr_err("INFO: trying to register non-static key.\n");
pr_err("the code is fine but needs lockdep annotation.\n");
pr_err("turning off the locking correctness validator.\n");
dump_stack();
return false;
}
return true;
}
#ifdef CONFIG_DEBUG_LOCKDEP
/* Check whether element @e occurs in list @h */
static bool in_list(struct list_head *e, struct list_head *h)
{
struct list_head *f;
list_for_each(f, h) {
if (e == f)
return true;
}
return false;
}
/*
* Check whether entry @e occurs in any of the locks_after or locks_before
* lists.
*/
static bool in_any_class_list(struct list_head *e)
{
struct lock_class *class;
int i;
for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
class = &lock_classes[i];
if (in_list(e, &class->locks_after) ||
in_list(e, &class->locks_before))
return true;
}
return false;
}
static bool class_lock_list_valid(struct lock_class *c, struct list_head *h)
{
struct lock_list *e;
list_for_each_entry(e, h, entry) {
if (e->links_to != c) {
printk(KERN_INFO "class %s: mismatch for lock entry %ld; class %s <> %s",
c->name ? : "(?)",
(unsigned long)(e - list_entries),
e->links_to && e->links_to->name ?
e->links_to->name : "(?)",
e->class && e->class->name ? e->class->name :
"(?)");
return false;
}
}
return true;
}
#ifdef CONFIG_PROVE_LOCKING
static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
#endif
static bool check_lock_chain_key(struct lock_chain *chain)
{
#ifdef CONFIG_PROVE_LOCKING
u64 chain_key = 0;
int i;
for (i = chain->base; i < chain->base + chain->depth; i++)
chain_key = iterate_chain_key(chain_key, chain_hlocks[i] + 1);
/*
* The 'unsigned long long' casts avoid that a compiler warning
* is reported when building tools/lib/lockdep.
*/
if (chain->chain_key != chain_key) {
printk(KERN_INFO "chain %lld: key %#llx <> %#llx\n",
(unsigned long long)(chain - lock_chains),
(unsigned long long)chain->chain_key,
(unsigned long long)chain_key);
return false;
}
#endif
return true;
}
static bool in_any_zapped_class_list(struct lock_class *class)
{
struct pending_free *pf;
int i;
for (i = 0, pf = delayed_free.pf; i < ARRAY_SIZE(delayed_free.pf); i++, pf++) {
if (in_list(&class->lock_entry, &pf->zapped))
return true;
}
return false;
}
static bool __check_data_structures(void)
{
struct lock_class *class;
struct lock_chain *chain;
struct hlist_head *head;
struct lock_list *e;
int i;
/* Check whether all classes occur in a lock list. */
for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
class = &lock_classes[i];
if (!in_list(&class->lock_entry, &all_lock_classes) &&
!in_list(&class->lock_entry, &free_lock_classes) &&
!in_any_zapped_class_list(class)) {
printk(KERN_INFO "class %px/%s is not in any class list\n",
class, class->name ? : "(?)");
return false;
}
}
/* Check whether all classes have valid lock lists. */
for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
class = &lock_classes[i];
if (!class_lock_list_valid(class, &class->locks_before))
return false;
if (!class_lock_list_valid(class, &class->locks_after))
return false;
}
/* Check the chain_key of all lock chains. */
for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) {
head = chainhash_table + i;
hlist_for_each_entry_rcu(chain, head, entry) {
if (!check_lock_chain_key(chain))
return false;
}
}
/*
* Check whether all list entries that are in use occur in a class
* lock list.
*/
for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
e = list_entries + i;
if (!in_any_class_list(&e->entry)) {
printk(KERN_INFO "list entry %d is not in any class list; class %s <> %s\n",
(unsigned int)(e - list_entries),
e->class->name ? : "(?)",
e->links_to->name ? : "(?)");
return false;
}
}
/*
* Check whether all list entries that are not in use do not occur in
* a class lock list.
*/
for_each_clear_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
e = list_entries + i;
if (in_any_class_list(&e->entry)) {
printk(KERN_INFO "list entry %d occurs in a class list; class %s <> %s\n",
(unsigned int)(e - list_entries),
e->class && e->class->name ? e->class->name :
"(?)",
e->links_to && e->links_to->name ?
e->links_to->name : "(?)");
return false;
}
}
return true;
}
int check_consistency = 0;
module_param(check_consistency, int, 0644);
static void check_data_structures(void)
{
static bool once = false;
if (check_consistency && !once) {
if (!__check_data_structures()) {
once = true;
WARN_ON(once);
}
}
}
#else /* CONFIG_DEBUG_LOCKDEP */
static inline void check_data_structures(void) { }
#endif /* CONFIG_DEBUG_LOCKDEP */
/*
* Initialize the lock_classes[] array elements, the free_lock_classes list
* and also the delayed_free structure.
*/
static void init_data_structures_once(void)
{
static bool ds_initialized, rcu_head_initialized;
int i;
if (likely(rcu_head_initialized))
return;
if (system_state >= SYSTEM_SCHEDULING) {
init_rcu_head(&delayed_free.rcu_head);
rcu_head_initialized = true;
}
if (ds_initialized)
return;
ds_initialized = true;
INIT_LIST_HEAD(&delayed_free.pf[0].zapped);
INIT_LIST_HEAD(&delayed_free.pf[1].zapped);
for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
list_add_tail(&lock_classes[i].lock_entry, &free_lock_classes);
INIT_LIST_HEAD(&lock_classes[i].locks_after);
INIT_LIST_HEAD(&lock_classes[i].locks_before);
}
}
static inline struct hlist_head *keyhashentry(const struct lock_class_key *key)
{
unsigned long hash = hash_long((uintptr_t)key, KEYHASH_BITS);
return lock_keys_hash + hash;
}
/* Register a dynamically allocated key. */
void lockdep_register_key(struct lock_class_key *key)
{
struct hlist_head *hash_head;
struct lock_class_key *k;
unsigned long flags;
if (WARN_ON_ONCE(static_obj(key)))
return;
hash_head = keyhashentry(key);
raw_local_irq_save(flags);
if (!graph_lock())
goto restore_irqs;
hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
if (WARN_ON_ONCE(k == key))
goto out_unlock;
}
hlist_add_head_rcu(&key->hash_entry, hash_head);
out_unlock:
graph_unlock();
restore_irqs:
raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lockdep_register_key);
/* Check whether a key has been registered as a dynamic key. */
static bool is_dynamic_key(const struct lock_class_key *key)
{
struct hlist_head *hash_head;
struct lock_class_key *k;
bool found = false;
if (WARN_ON_ONCE(static_obj(key)))
return false;
/*
* If lock debugging is disabled lock_keys_hash[] may contain
* pointers to memory that has already been freed. Avoid triggering
* a use-after-free in that case by returning early.
*/
if (!debug_locks)
return true;
hash_head = keyhashentry(key);
rcu_read_lock();
hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
if (k == key) {
found = true;
break;
}
}
rcu_read_unlock();
return found;
}
/*
* Register a lock's class in the hash-table, if the class is not present
* yet. Otherwise we look it up. We cache the result in the lock object
* itself, so actual lookup of the hash should be once per lock object.
*/
static struct lock_class *
register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
{
struct lockdep_subclass_key *key;
struct hlist_head *hash_head;
struct lock_class *class;
DEBUG_LOCKS_WARN_ON(!irqs_disabled());
class = look_up_lock_class(lock, subclass);
if (likely(class))
goto out_set_class_cache;
if (!lock->key) {
if (!assign_lock_key(lock))
return NULL;
} else if (!static_obj(lock->key) && !is_dynamic_key(lock->key)) {
return NULL;
}
key = lock->key->subkeys + subclass;
hash_head = classhashentry(key);
if (!graph_lock()) {
return NULL;
}
/*
* We have to do the hash-walk again, to avoid races
* with another CPU:
*/
hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
if (class->key == key)
goto out_unlock_set;
}
init_data_structures_once();
/* Allocate a new lock class and add it to the hash. */
class = list_first_entry_or_null(&free_lock_classes, typeof(*class),
lock_entry);
if (!class) {
if (!debug_locks_off_graph_unlock()) {
return NULL;
}
print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
dump_stack();
return NULL;
}
nr_lock_classes++;
debug_atomic_inc(nr_unused_locks);
class->key = key;
class->name = lock->name;
class->subclass = subclass;
WARN_ON_ONCE(!list_empty(&class->locks_before));
WARN_ON_ONCE(!list_empty(&class->locks_after));
class->name_version = count_matching_names(class);
/*
* We use RCU's safe list-add method to make
* parallel walking of the hash-list safe:
*/
hlist_add_head_rcu(&class->hash_entry, hash_head);
/*
* Remove the class from the free list and add it to the global list
* of classes.
*/
list_move_tail(&class->lock_entry, &all_lock_classes);
if (verbose(class)) {
graph_unlock();
printk("\nnew class %px: %s", class->key, class->name);
if (class->name_version > 1)
printk(KERN_CONT "#%d", class->name_version);
printk(KERN_CONT "\n");
dump_stack();
if (!graph_lock()) {
return NULL;
}
}
out_unlock_set:
graph_unlock();
out_set_class_cache:
if (!subclass || force)
lock->class_cache[0] = class;
else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
lock->class_cache[subclass] = class;
/*
* Hash collision, did we smoke some? We found a class with a matching
* hash but the subclass -- which is hashed in -- didn't match.
*/
if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
return NULL;
return class;
}
#ifdef CONFIG_PROVE_LOCKING
/*
* Allocate a lockdep entry. (assumes the graph_lock held, returns
* with NULL on failure)
*/
static struct lock_list *alloc_list_entry(void)
{
int idx = find_first_zero_bit(list_entries_in_use,
ARRAY_SIZE(list_entries));
if (idx >= ARRAY_SIZE(list_entries)) {
if (!debug_locks_off_graph_unlock())
return NULL;
print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
dump_stack();
return NULL;
}
nr_list_entries++;
__set_bit(idx, list_entries_in_use);
return list_entries + idx;
}
/*
* Add a new dependency to the head of the list:
*/
static int add_lock_to_list(struct lock_class *this,
struct lock_class *links_to, struct list_head *head,
unsigned long ip, int distance,
struct lock_trace *trace)
{
struct lock_list *entry;
/*
* Lock not present yet - get a new dependency struct and
* add it to the list:
*/
entry = alloc_list_entry();
if (!entry)
return 0;
entry->class = this;
entry->links_to = links_to;
entry->distance = distance;
entry->trace = *trace;
/*
* Both allocation and removal are done under the graph lock; but
* iteration is under RCU-sched; see look_up_lock_class() and
* lockdep_free_key_range().
*/
list_add_tail_rcu(&entry->entry, head);
return 1;
}
/*
* For good efficiency of modular, we use power of 2
*/
#define MAX_CIRCULAR_QUEUE_SIZE 4096UL
#define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
/*
* The circular_queue and helpers is used to implement the
* breadth-first search(BFS)algorithem, by which we can build
* the shortest path from the next lock to be acquired to the
* previous held lock if there is a circular between them.
*/
struct circular_queue {
unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
unsigned int front, rear;
};
static struct circular_queue lock_cq;
unsigned int max_bfs_queue_depth;
static unsigned int lockdep_dependency_gen_id;
static inline void __cq_init(struct circular_queue *cq)
{
cq->front = cq->rear = 0;
lockdep_dependency_gen_id++;
}
static inline int __cq_empty(struct circular_queue *cq)
{
return (cq->front == cq->rear);
}
static inline int __cq_full(struct circular_queue *cq)
{
return ((cq->rear + 1) & CQ_MASK) == cq->front;
}
static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
{
if (__cq_full(cq))
return -1;
cq->element[cq->rear] = elem;
cq->rear = (cq->rear + 1) & CQ_MASK;
return 0;
}
static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
{
if (__cq_empty(cq))
return -1;
*elem = cq->element[cq->front];
cq->front = (cq->front + 1) & CQ_MASK;
return 0;
}
static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
{
return (cq->rear - cq->front) & CQ_MASK;
}
static inline void mark_lock_accessed(struct lock_list *lock,
struct lock_list *parent)
{
unsigned long nr;
nr = lock - list_entries;
WARN_ON(nr >= ARRAY_SIZE(list_entries)); /* Out-of-bounds, input fail */
lock->parent = parent;
lock->class->dep_gen_id = lockdep_dependency_gen_id;
}
static inline unsigned long lock_accessed(struct lock_list *lock)
{
unsigned long nr;
nr = lock - list_entries;
WARN_ON(nr >= ARRAY_SIZE(list_entries)); /* Out-of-bounds, input fail */
return lock->class->dep_gen_id == lockdep_dependency_gen_id;
}
static inline struct lock_list *get_lock_parent(struct lock_list *child)
{
return child->parent;
}
static inline int get_lock_depth(struct lock_list *child)
{
int depth = 0;
struct lock_list *parent;
while ((parent = get_lock_parent(child))) {
child = parent;
depth++;
}
return depth;
}
static int __bfs(struct lock_list *source_entry,
void *data,
int (*match)(struct lock_list *entry, void *data),
struct lock_list **target_entry,
int forward)
{
struct lock_list *entry;
struct list_head *head;
struct circular_queue *cq = &lock_cq;
int ret = 1;
if (match(source_entry, data)) {
*target_entry = source_entry;
ret = 0;
goto exit;
}
if (forward)
head = &source_entry->class->locks_after;
else
head = &source_entry->class->locks_before;
if (list_empty(head))
goto exit;
__cq_init(cq);
__cq_enqueue(cq, (unsigned long)source_entry);
while (!__cq_empty(cq)) {
struct lock_list *lock;
__cq_dequeue(cq, (unsigned long *)&lock);
if (!lock->class) {
ret = -2;
goto exit;
}
if (forward)
head = &lock->class->locks_after;
else
head = &lock->class->locks_before;
DEBUG_LOCKS_WARN_ON(!irqs_disabled());
list_for_each_entry_rcu(entry, head, entry) {
if (!lock_accessed(entry)) {
unsigned int cq_depth;
mark_lock_accessed(entry, lock);
if (match(entry, data)) {
*target_entry = entry;
ret = 0;
goto exit;
}
if (__cq_enqueue(cq, (unsigned long)entry)) {
ret = -1;
goto exit;
}
cq_depth = __cq_get_elem_count(cq);
if (max_bfs_queue_depth < cq_depth)
max_bfs_queue_depth = cq_depth;
}
}
}
exit:
return ret;
}
static inline int __bfs_forwards(struct lock_list *src_entry,
void *data,
int (*match)(struct lock_list *entry, void *data),
struct lock_list **target_entry)
{
return __bfs(src_entry, data, match, target_entry, 1);
}
static inline int __bfs_backwards(struct lock_list *src_entry,
void *data,
int (*match)(struct lock_list *entry, void *data),
struct lock_list **target_entry)
{
return __bfs(src_entry, data, match, target_entry, 0);
}
/*
* Recursive, forwards-direction lock-dependency checking, used for
* both noncyclic checking and for hardirq-unsafe/softirq-unsafe
* checking.
*/
static void print_lock_trace(struct lock_trace *trace, unsigned int spaces)
{
unsigned long *entries = stack_trace + trace->offset;
stack_trace_print(entries, trace->nr_entries, spaces);
}
/*
* Print a dependency chain entry (this is only done when a deadlock
* has been detected):
*/
static noinline int
print_circular_bug_entry(struct lock_list *target, int depth)
{
if (debug_locks_silent)
return 0;
printk("\n-> #%u", depth);
print_lock_name(target->class);
printk(KERN_CONT ":\n");
print_lock_trace(&target->trace, 6);
return 0;
}
static void
print_circular_lock_scenario(struct held_lock *src,
struct held_lock *tgt,
struct lock_list *prt)
{
struct lock_class *source = hlock_class(src);
struct lock_class *target = hlock_class(tgt);
struct lock_class *parent = prt->class;
/*
* A direct locking problem where unsafe_class lock is taken
* directly by safe_class lock, then all we need to show
* is the deadlock scenario, as it is obvious that the
* unsafe lock is taken under the safe lock.
*
* But if there is a chain instead, where the safe lock takes
* an intermediate lock (middle_class) where this lock is
* not the same as the safe lock, then the lock chain is
* used to describe the problem. Otherwise we would need
* to show a different CPU case for each link in the chain
* from the safe_class lock to the unsafe_class lock.
*/
if (parent != source) {
printk("Chain exists of:\n ");
__print_lock_name(source);
printk(KERN_CONT " --> ");
__print_lock_name(parent);
printk(KERN_CONT " --> ");
__print_lock_name(target);
printk(KERN_CONT "\n\n");
}
printk(" Possible unsafe locking scenario:\n\n");
printk(" CPU0 CPU1\n");
printk(" ---- ----\n");
printk(" lock(");
__print_lock_name(target);
printk(KERN_CONT ");\n");
printk(" lock(");
__print_lock_name(parent);
printk(KERN_CONT ");\n");
printk(" lock(");
__print_lock_name(target);
printk(KERN_CONT ");\n");
printk(" lock(");
__print_lock_name(source);
printk(KERN_CONT ");\n");
printk("\n *** DEADLOCK ***\n\n");
}
/*
* When a circular dependency is detected, print the
* header first:
*/
static noinline int
print_circular_bug_header(struct lock_list *entry, unsigned int depth,
struct held_lock *check_src,
struct held_lock *check_tgt)
{
struct task_struct *curr = current;
if (debug_locks_silent)
return 0;
pr_warn("\n");
pr_warn("======================================================\n");
pr_warn("WARNING: possible circular locking dependency detected\n");
print_kernel_ident();
pr_warn("------------------------------------------------------\n");
pr_warn("%s/%d is trying to acquire lock:\n",
curr->comm, task_pid_nr(curr));
print_lock(check_src);
pr_warn("\nbut task is already holding lock:\n");
print_lock(check_tgt);
pr_warn("\nwhich lock already depends on the new lock.\n\n");
pr_warn("\nthe existing dependency chain (in reverse order) is:\n");
print_circular_bug_entry(entry, depth);
return 0;
}
static inline int class_equal(struct lock_list *entry, void *data)
{
return entry->class == data;
}
static noinline int print_circular_bug(struct lock_list *this,
struct lock_list *target,
struct held_lock *check_src,
struct held_lock *check_tgt)
{
struct task_struct *curr = current;
struct lock_list *parent;
struct lock_list *first_parent;
int depth;
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
return 0;
if (!save_trace(&this->trace))
return 0;
depth = get_lock_depth(target);
print_circular_bug_header(target, depth, check_src, check_tgt);
parent = get_lock_parent(target);
first_parent = parent;
while (parent) {
print_circular_bug_entry(parent, --depth);
parent = get_lock_parent(parent);
}
printk("\nother info that might help us debug this:\n\n");
print_circular_lock_scenario(check_src, check_tgt,
first_parent);
lockdep_print_held_locks(curr);
printk("\nstack backtrace:\n");
dump_stack();
return 0;
}
static noinline int print_bfs_bug(int ret)
{
if (!debug_locks_off_graph_unlock())
return 0;
/*
* Breadth-first-search failed, graph got corrupted?
*/
WARN(1, "lockdep bfs error:%d\n", ret);
return 0;
}
static int noop_count(struct lock_list *entry, void *data)
{
(*(unsigned long *)data)++;
return 0;
}
static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
{
unsigned long count = 0;
struct lock_list *uninitialized_var(target_entry);
__bfs_forwards(this, (void *)&count, noop_count, &target_entry);
return count;
}
unsigned long lockdep_count_forward_deps(struct lock_class *class)
{
unsigned long ret, flags;
struct lock_list this;
this.parent = NULL;
this.class = class;
raw_local_irq_save(flags);
arch_spin_lock(&lockdep_lock);
ret = __lockdep_count_forward_deps(&this);
arch_spin_unlock(&lockdep_lock);
raw_local_irq_restore(flags);
return ret;
}
static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
{
unsigned long count = 0;
struct lock_list *uninitialized_var(target_entry);
__bfs_backwards(this, (void *)&count, noop_count, &target_entry);
return count;
}
unsigned long lockdep_count_backward_deps(struct lock_class *class)
{
unsigned long ret, flags;
struct lock_list this;
this.parent = NULL;
this.class = class;
raw_local_irq_save(flags);
arch_spin_lock(&lockdep_lock);
ret = __lockdep_count_backward_deps(&this);
arch_spin_unlock(&lockdep_lock);
raw_local_irq_restore(flags);
return ret;
}
/*
* Prove that the dependency graph starting at <entry> can not
* lead to <target>. Print an error and return 0 if it does.
*/
static noinline int
check_noncircular(struct lock_list *root, struct lock_class *target,
struct lock_list **target_entry)
{
int result;
debug_atomic_inc(nr_cyclic_checks);
result = __bfs_forwards(root, target, class_equal, target_entry);
return result;
}
static noinline int
check_redundant(struct lock_list *root, struct lock_class *target,
struct lock_list **target_entry)
{
int result;
debug_atomic_inc(nr_redundant_checks);
result = __bfs_forwards(root, target, class_equal, target_entry);
return result;
}
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
static inline int usage_accumulate(struct lock_list *entry, void *mask)
{
*(unsigned long *)mask |= entry->class->usage_mask;
return 0;
}
/*
* Forwards and backwards subgraph searching, for the purposes of
* proving that two subgraphs can be connected by a new dependency
* without creating any illegal irq-safe -> irq-unsafe lock dependency.
*/
static inline int usage_match(struct lock_list *entry, void *mask)
{
return entry->class->usage_mask & *(unsigned long *)mask;
}
/*
* Find a node in the forwards-direction dependency sub-graph starting
* at @root->class that matches @bit.
*
* Return 0 if such a node exists in the subgraph, and put that node
* into *@target_entry.
*
* Return 1 otherwise and keep *@target_entry unchanged.
* Return <0 on error.
*/
static int
find_usage_forwards(struct lock_list *root, unsigned long usage_mask,
struct lock_list **target_entry)
{
int result;
debug_atomic_inc(nr_find_usage_forwards_checks);
result = __bfs_forwards(root, &usage_mask, usage_match, target_entry);
return result;
}
/*
* Find a node in the backwards-direction dependency sub-graph starting
* at @root->class that matches @bit.
*
* Return 0 if such a node exists in the subgraph, and put that node
* into *@target_entry.
*
* Return 1 otherwise and keep *@target_entry unchanged.
* Return <0 on error.
*/
static int
find_usage_backwards(struct lock_list *root, unsigned long usage_mask,
struct lock_list **target_entry)
{
int result;
debug_atomic_inc(nr_find_usage_backwards_checks);
result = __bfs_backwards(root, &usage_mask, usage_match, target_entry);
return result;
}
static void print_lock_class_header(struct lock_class *class, int depth)
{
int bit;
printk("%*s->", depth, "");
print_lock_name(class);
#ifdef CONFIG_DEBUG_LOCKDEP
printk(KERN_CONT " ops: %lu", debug_class_ops_read(class));
#endif
printk(KERN_CONT " {\n");
for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
if (class->usage_mask & (1 << bit)) {
int len = depth;
len += printk("%*s %s", depth, "", usage_str[bit]);
len += printk(KERN_CONT " at:\n");
print_lock_trace(class->usage_traces + bit, len);
}
}
printk("%*s }\n", depth, "");
printk("%*s ... key at: [<%px>] %pS\n",
depth, "", class->key, class->key);
}
/*
* printk the shortest lock dependencies from @start to @end in reverse order:
*/
static void __used
print_shortest_lock_dependencies(struct lock_list *leaf,
struct lock_list *root)
{
struct lock_list *entry = leaf;
int depth;
/*compute depth from generated tree by BFS*/
depth = get_lock_depth(leaf);
do {
print_lock_class_header(entry->class, depth);
printk("%*s ... acquired at:\n", depth, "");
print_lock_trace(&entry->trace, 2);
printk("\n");
if (depth == 0 && (entry != root)) {
printk("lockdep:%s bad path found in chain graph\n", __func__);
break;
}
entry = get_lock_parent(entry);
depth--;
} while (entry && (depth >= 0));
return;
}
static void
print_irq_lock_scenario(struct lock_list *safe_entry,
struct lock_list *unsafe_entry,
struct lock_class *prev_class,
struct lock_class *next_class)
{
struct lock_class *safe_class = safe_entry->class;
struct lock_class *unsafe_class = unsafe_entry->class;
struct lock_class *middle_class = prev_class;
if (middle_class == safe_class)
middle_class = next_class;
/*
* A direct locking problem where unsafe_class lock is taken
* directly by safe_class lock, then all we need to show
* is the deadlock scenario, as it is obvious that the
* unsafe lock is taken under the safe lock.
*
* But if there is a chain instead, where the safe lock takes
* an intermediate lock (middle_class) where this lock is
* not the same as the safe lock, then the lock chain is
* used to describe the problem. Otherwise we would need
* to show a different CPU case for each link in the chain
* from the safe_class lock to the unsafe_class lock.
*/
if (middle_class != unsafe_class) {
printk("Chain exists of:\n ");
__print_lock_name(safe_class);
printk(KERN_CONT " --> ");
__print_lock_name(middle_class);
printk(KERN_CONT " --> ");
__print_lock_name(unsafe_class);
printk(KERN_CONT "\n\n");
}
printk(" Possible interrupt unsafe locking scenario:\n\n");
printk(" CPU0 CPU1\n");
printk(" ---- ----\n");
printk(" lock(");
__print_lock_name(unsafe_class);
printk(KERN_CONT ");\n");
printk(" local_irq_disable();\n");
printk(" lock(");
__print_lock_name(safe_class);
printk(KERN_CONT ");\n");
printk(" lock(");
__print_lock_name(middle_class);
printk(KERN_CONT ");\n");
printk(" <Interrupt>\n");
printk(" lock(");
__print_lock_name(safe_class);
printk(KERN_CONT ");\n");
printk("\n *** DEADLOCK ***\n\n");
}
static int
print_bad_irq_dependency(struct task_struct *curr,
struct lock_list *prev_root,
struct lock_list *next_root,
struct lock_list *backwards_entry,
struct lock_list *forwards_entry,
struct held_lock *prev,
struct held_lock *next,
enum lock_usage_bit bit1,
enum lock_usage_bit bit2,
const char *irqclass)
{
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
return 0;
pr_warn("\n");
pr_warn("=====================================================\n");
pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n",
irqclass, irqclass);
print_kernel_ident();
pr_warn("-----------------------------------------------------\n");
pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
curr->comm, task_pid_nr(curr),
curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
curr->hardirqs_enabled,
curr->softirqs_enabled);
print_lock(next);
pr_warn("\nand this task is already holding:\n");
print_lock(prev);
pr_warn("which would create a new lock dependency:\n");
print_lock_name(hlock_class(prev));
pr_cont(" ->");
print_lock_name(hlock_class(next));
pr_cont("\n");
pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n",
irqclass);
print_lock_name(backwards_entry->class);
pr_warn("\n... which became %s-irq-safe at:\n", irqclass);
print_lock_trace(backwards_entry->class->usage_traces + bit1, 1);
pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass);
print_lock_name(forwards_entry->class);
pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass);
pr_warn("...");
print_lock_trace(forwards_entry->class->usage_traces + bit2, 1);
pr_warn("\nother info that might help us debug this:\n\n");
print_irq_lock_scenario(backwards_entry, forwards_entry,
hlock_class(prev), hlock_class(next));
lockdep_print_held_locks(curr);
pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass);
if (!save_trace(&prev_root->trace))
return 0;
print_shortest_lock_dependencies(backwards_entry, prev_root);
pr_warn("\nthe dependencies between the lock to be acquired");
pr_warn(" and %s-irq-unsafe lock:\n", irqclass);
if (!save_trace(&next_root->trace))
return 0;
print_shortest_lock_dependencies(forwards_entry, next_root);
pr_warn("\nstack backtrace:\n");
dump_stack();
return 0;
}
static const char *state_names[] = {
#define LOCKDEP_STATE(__STATE) \
__stringify(__STATE),
#include "lockdep_states.h"
#undef LOCKDEP_STATE
};
static const char *state_rnames[] = {
#define LOCKDEP_STATE(__STATE) \
__stringify(__STATE)"-READ",
#include "lockdep_states.h"
#undef LOCKDEP_STATE
};
static inline const char *state_name(enum lock_usage_bit bit)
{
if (bit & LOCK_USAGE_READ_MASK)
return state_rnames[bit >> LOCK_USAGE_DIR_MASK];
else
return state_names[bit >> LOCK_USAGE_DIR_MASK];
}
/*
* The bit number is encoded like:
*
* bit0: 0 exclusive, 1 read lock
* bit1: 0 used in irq, 1 irq enabled
* bit2-n: state
*/
static int exclusive_bit(int new_bit)
{
int state = new_bit & LOCK_USAGE_STATE_MASK;
int dir = new_bit & LOCK_USAGE_DIR_MASK;
/*
* keep state, bit flip the direction and strip read.
*/
return state | (dir ^ LOCK_USAGE_DIR_MASK);
}
/*
* Observe that when given a bitmask where each bitnr is encoded as above, a
* right shift of the mask transforms the individual bitnrs as -1 and
* conversely, a left shift transforms into +1 for the individual bitnrs.
*
* So for all bits whose number have LOCK_ENABLED_* set (bitnr1 == 1), we can
* create the mask with those bit numbers using LOCK_USED_IN_* (bitnr1 == 0)
* instead by subtracting the bit number by 2, or shifting the mask right by 2.
*
* Similarly, bitnr1 == 0 becomes bitnr1 == 1 by adding 2, or shifting left 2.
*
* So split the mask (note that LOCKF_ENABLED_IRQ_ALL|LOCKF_USED_IN_IRQ_ALL is
* all bits set) and recompose with bitnr1 flipped.
*/
static unsigned long invert_dir_mask(unsigned long mask)
{
unsigned long excl = 0;
/* Invert dir */
excl |= (mask & LOCKF_ENABLED_IRQ_ALL) >> LOCK_USAGE_DIR_MASK;
excl |= (mask & LOCKF_USED_IN_IRQ_ALL) << LOCK_USAGE_DIR_MASK;
return excl;
}
/*
* As above, we clear bitnr0 (LOCK_*_READ off) with bitmask ops. First, for all
* bits with bitnr0 set (LOCK_*_READ), add those with bitnr0 cleared (LOCK_*).
* And then mask out all bitnr0.
*/
static unsigned long exclusive_mask(unsigned long mask)
{
unsigned long excl = invert_dir_mask(mask);
/* Strip read */
excl |= (excl & LOCKF_IRQ_READ) >> LOCK_USAGE_READ_MASK;
excl &= ~LOCKF_IRQ_READ;
return excl;
}
/*
* Retrieve the _possible_ original mask to which @mask is
* exclusive. Ie: this is the opposite of exclusive_mask().
* Note that 2 possible original bits can match an exclusive
* bit: one has LOCK_USAGE_READ_MASK set, the other has it
* cleared. So both are returned for each exclusive bit.
*/
static unsigned long original_mask(unsigned long mask)
{
unsigned long excl = invert_dir_mask(mask);
/* Include read in existing usages */
excl |= (excl & LOCKF_IRQ) << LOCK_USAGE_READ_MASK;
return excl;
}
/*
* Find the first pair of bit match between an original
* usage mask and an exclusive usage mask.
*/
static int find_exclusive_match(unsigned long mask,
unsigned long excl_mask,
enum lock_usage_bit *bitp,
enum lock_usage_bit *excl_bitp)
{
int bit, excl;
for_each_set_bit(bit, &mask, LOCK_USED) {
excl = exclusive_bit(bit);
if (excl_mask & lock_flag(excl)) {
*bitp = bit;
*excl_bitp = excl;
return 0;
}
}
return -1;
}
/*
* Prove that the new dependency does not connect a hardirq-safe(-read)
* lock with a hardirq-unsafe lock - to achieve this we search
* the backwards-subgraph starting at <prev>, and the
* forwards-subgraph starting at <next>:
*/
static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
struct held_lock *next)
{
unsigned long usage_mask = 0, forward_mask, backward_mask;
enum lock_usage_bit forward_bit = 0, backward_bit = 0;
struct lock_list *uninitialized_var(target_entry1);
struct lock_list *uninitialized_var(target_entry);
struct lock_list this, that;
int ret;
/*
* Step 1: gather all hard/soft IRQs usages backward in an
* accumulated usage mask.
*/
this.parent = NULL;
this.class = hlock_class(prev);
ret = __bfs_backwards(&this, &usage_mask, usage_accumulate, NULL);
if (ret < 0)
return print_bfs_bug(ret);
usage_mask &= LOCKF_USED_IN_IRQ_ALL;
if (!usage_mask)
return 1;
/*
* Step 2: find exclusive uses forward that match the previous
* backward accumulated mask.
*/
forward_mask = exclusive_mask(usage_mask);
that.parent = NULL;
that.class = hlock_class(next);
ret = find_usage_forwards(&that, forward_mask, &target_entry1);
if (ret < 0)
return print_bfs_bug(ret);
if (ret == 1)
return ret;
/*
* Step 3: we found a bad match! Now retrieve a lock from the backward
* list whose usage mask matches the exclusive usage mask from the
* lock found on the forward list.
*/
backward_mask = original_mask(target_entry1->class->usage_mask);
ret = find_usage_backwards(&this, backward_mask, &target_entry);
if (ret < 0)
return print_bfs_bug(ret);
if (DEBUG_LOCKS_WARN_ON(ret == 1))
return 1;
/*
* Step 4: narrow down to a pair of incompatible usage bits
* and report it.
*/
ret = find_exclusive_match(target_entry->class->usage_mask,
target_entry1->class->usage_mask,
&backward_bit, &forward_bit);
if (DEBUG_LOCKS_WARN_ON(ret == -1))
return 1;
return print_bad_irq_dependency(curr, &this, &that,
target_entry, target_entry1,
prev, next,
backward_bit, forward_bit,
state_name(backward_bit));
}
static void inc_chains(void)
{
if (current->hardirq_context)
nr_hardirq_chains++;
else {
if (current->softirq_context)
nr_softirq_chains++;
else
nr_process_chains++;
}
}
#else
static inline int check_irq_usage(struct task_struct *curr,
struct held_lock *prev, struct held_lock *next)
{
return 1;
}
static inline void inc_chains(void)
{
nr_process_chains++;
}
#endif
static void
print_deadlock_scenario(struct held_lock *nxt,
struct held_lock *prv)
{
struct lock_class *next = hlock_class(nxt);
struct lock_class *prev = hlock_class(prv);
printk(" Possible unsafe locking scenario:\n\n");
printk(" CPU0\n");
printk(" ----\n");
printk(" lock(");
__print_lock_name(prev);
printk(KERN_CONT ");\n");
printk(" lock(");
__print_lock_name(next);
printk(KERN_CONT ");\n");
printk("\n *** DEADLOCK ***\n\n");
printk(" May be due to missing lock nesting notation\n\n");
}
static int
print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
struct held_lock *next)
{
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
return 0;
pr_warn("\n");
pr_warn("============================================\n");
pr_warn("WARNING: possible recursive locking detected\n");
print_kernel_ident();
pr_warn("--------------------------------------------\n");
pr_warn("%s/%d is trying to acquire lock:\n",
curr->comm, task_pid_nr(curr));
print_lock(next);
pr_warn("\nbut task is already holding lock:\n");
print_lock(prev);
pr_warn("\nother info that might help us debug this:\n");
print_deadlock_scenario(next, prev);
lockdep_print_held_locks(curr);
pr_warn("\nstack backtrace:\n");
dump_stack();
return 0;
}
/*
* Check whether we are holding such a class already.
*
* (Note that this has to be done separately, because the graph cannot
* detect such classes of deadlocks.)
*
* Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
*/
static int
check_deadlock(struct task_struct *curr, struct held_lock *next,
struct lockdep_map *next_instance, int read)
{
struct held_lock *prev;
struct held_lock *nest = NULL;
int i;
for (i = 0; i < curr->lockdep_depth; i++) {
prev = curr->held_locks + i;
if (prev->instance == next->nest_lock)
nest = prev;
if (hlock_class(prev) != hlock_class(next))
continue;
/*
* Allow read-after-read recursion of the same
* lock class (i.e. read_lock(lock)+read_lock(lock)):
*/
if ((read == 2) && prev->read)
return 2;
/*
* We're holding the nest_lock, which serializes this lock's
* nesting behaviour.
*/
if (nest)
return 2;
return print_deadlock_bug(curr, prev, next);
}
return 1;
}
/*
* There was a chain-cache miss, and we are about to add a new dependency
* to a previous lock. We recursively validate the following rules:
*
* - would the adding of the <prev> -> <next> dependency create a
* circular dependency in the graph? [== circular deadlock]
*
* - does the new prev->next dependency connect any hardirq-safe lock
* (in the full backwards-subgraph starting at <prev>) with any
* hardirq-unsafe lock (in the full forwards-subgraph starting at
* <next>)? [== illegal lock inversion with hardirq contexts]
*
* - does the new prev->next dependency connect any softirq-safe lock
* (in the full backwards-subgraph starting at <prev>) with any
* softirq-unsafe lock (in the full forwards-subgraph starting at
* <next>)? [== illegal lock inversion with softirq contexts]
*
* any of these scenarios could lead to a deadlock.
*
* Then if all the validations pass, we add the forwards and backwards
* dependency.
*/
static int
check_prev_add(struct task_struct *curr, struct held_lock *prev,
struct held_lock *next, int distance, struct lock_trace *trace)
{
struct lock_list *uninitialized_var(target_entry);
struct lock_list *entry;
struct lock_list this;
int ret;
if (!hlock_class(prev)->key || !hlock_class(next)->key) {
/*
* The warning statements below may trigger a use-after-free
* of the class name. It is better to trigger a use-after free
* and to have the class name most of the time instead of not
* having the class name available.
*/
WARN_ONCE(!debug_locks_silent && !hlock_class(prev)->key,
"Detected use-after-free of lock class %px/%s\n",
hlock_class(prev),
hlock_class(prev)->name);
WARN_ONCE(!debug_locks_silent && !hlock_class(next)->key,
"Detected use-after-free of lock class %px/%s\n",
hlock_class(next),
hlock_class(next)->name);
return 2;
}
/*
* Prove that the new <prev> -> <next> dependency would not
* create a circular dependency in the graph. (We do this by
* forward-recursing into the graph starting at <next>, and
* checking whether we can reach <prev>.)
*
* We are using global variables to control the recursion, to
* keep the stackframe size of the recursive functions low:
*/
this.class = hlock_class(next);
this.parent = NULL;
ret = check_noncircular(&this, hlock_class(prev), &target_entry);
if (unlikely(!ret)) {
if (!trace->nr_entries) {
/*
* If save_trace fails here, the printing might
* trigger a WARN but because of the !nr_entries it
* should not do bad things.
*/
save_trace(trace);
}
return print_circular_bug(&this, target_entry, next, prev);
}
else if (unlikely(ret < 0))
return print_bfs_bug(ret);
if (!check_irq_usage(curr, prev, next))
return 0;
/*
* For recursive read-locks we do all the dependency checks,
* but we dont store read-triggered dependencies (only
* write-triggered dependencies). This ensures that only the
* write-side dependencies matter, and that if for example a
* write-lock never takes any other locks, then the reads are
* equivalent to a NOP.
*/
if (next->read == 2 || prev->read == 2)
return 1;
/*
* Is the <prev> -> <next> dependency already present?
*
* (this may occur even though this is a new chain: consider
* e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
* chains - the second one will be new, but L1 already has
* L2 added to its dependency list, due to the first chain.)
*/
list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
if (entry->class == hlock_class(next)) {
if (distance == 1)
entry->distance = 1;
return 1;
}
}
/*
* Is the <prev> -> <next> link redundant?
*/
this.class = hlock_class(prev);
this.parent = NULL;
ret = check_redundant(&this, hlock_class(next), &target_entry);
if (!ret) {
debug_atomic_inc(nr_redundant);
return 2;
}
if (ret < 0)
return print_bfs_bug(ret);
if (!trace->nr_entries && !save_trace(trace))
return 0;
/*
* Ok, all validations passed, add the new lock
* to the previous lock's dependency list:
*/
ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
&hlock_class(prev)->locks_after,
next->acquire_ip, distance, trace);
if (!ret)
return 0;
ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
&hlock_class(next)->locks_before,
next->acquire_ip, distance, trace);
if (!ret)
return 0;
return 2;
}
/*
* Add the dependency to all directly-previous locks that are 'relevant'.
* The ones that are relevant are (in increasing distance from curr):
* all consecutive trylock entries and the final non-trylock entry - or
* the end of this context's lock-chain - whichever comes first.
*/
static int
check_prevs_add(struct task_struct *curr, struct held_lock *next)
{
struct lock_trace trace = { .nr_entries = 0 };
int depth = curr->lockdep_depth;
struct held_lock *hlock;
/*
* Debugging checks.
*
* Depth must not be zero for a non-head lock:
*/
if (!depth)
goto out_bug;
/*
* At least two relevant locks must exist for this
* to be a head:
*/
if (curr->held_locks[depth].irq_context !=
curr->held_locks[depth-1].irq_context)
goto out_bug;
for (;;) {
int distance = curr->lockdep_depth - depth + 1;
hlock = curr->held_locks + depth - 1;
/*
* Only non-recursive-read entries get new dependencies
* added:
*/
if (hlock->read != 2 && hlock->check) {
int ret = check_prev_add(curr, hlock, next, distance,
&trace);
if (!ret)
return 0;
/*
* Stop after the first non-trylock entry,
* as non-trylock entries have added their
* own direct dependencies already, so this
* lock is connected to them indirectly:
*/
if (!hlock->trylock)
break;
}
depth--;
/*
* End of lock-stack?
*/
if (!depth)
break;
/*
* Stop the search if we cross into another context:
*/
if (curr->held_locks[depth].irq_context !=
curr->held_locks[depth-1].irq_context)
break;
}
return 1;
out_bug:
if (!debug_locks_off_graph_unlock())
return 0;
/*
* Clearly we all shouldn't be here, but since we made it we
* can reliable say we messed up our state. See the above two
* gotos for reasons why we could possibly end up here.
*/
WARN_ON(1);
return 0;
}
struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
static DECLARE_BITMAP(lock_chains_in_use, MAX_LOCKDEP_CHAINS);
int nr_chain_hlocks;
static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
{
return lock_classes + chain_hlocks[chain->base + i];
}
/*
* Returns the index of the first held_lock of the current chain
*/
static inline int get_first_held_lock(struct task_struct *curr,
struct held_lock *hlock)
{
int i;
struct held_lock *hlock_curr;
for (i = curr->lockdep_depth - 1; i >= 0; i--) {
hlock_curr = curr->held_locks + i;
if (hlock_curr->irq_context != hlock->irq_context)
break;
}
return ++i;
}
#ifdef CONFIG_DEBUG_LOCKDEP
/*
* Returns the next chain_key iteration
*/
static u64 print_chain_key_iteration(int class_idx, u64 chain_key)
{
u64 new_chain_key = iterate_chain_key(chain_key, class_idx);
printk(" class_idx:%d -> chain_key:%016Lx",
class_idx,
(unsigned long long)new_chain_key);
return new_chain_key;
}
static void
print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next)
{
struct held_lock *hlock;
u64 chain_key = 0;
int depth = curr->lockdep_depth;
int i;
printk("depth: %u\n", depth + 1);
for (i = get_first_held_lock(curr, hlock_next); i < depth; i++) {
hlock = curr->held_locks + i;
chain_key = print_chain_key_iteration(hlock->class_idx, chain_key);
print_lock(hlock);
}
print_chain_key_iteration(hlock_next->class_idx, chain_key);
print_lock(hlock_next);
}
static void print_chain_keys_chain(struct lock_chain *chain)
{
int i;
u64 chain_key = 0;
int class_id;
printk("depth: %u\n", chain->depth);
for (i = 0; i < chain->depth; i++) {
class_id = chain_hlocks[chain->base + i];
chain_key = print_chain_key_iteration(class_id + 1, chain_key);
print_lock_name(lock_classes + class_id);
printk("\n");
}
}
static void print_collision(struct task_struct *curr,
struct held_lock *hlock_next,
struct lock_chain *chain)
{
pr_warn("\n");
pr_warn("============================\n");
pr_warn("WARNING: chain_key collision\n");
print_kernel_ident();
pr_warn("----------------------------\n");
pr_warn("%s/%d: ", current->comm, task_pid_nr(current));
pr_warn("Hash chain already cached but the contents don't match!\n");
pr_warn("Held locks:");
print_chain_keys_held_locks(curr, hlock_next);
pr_warn("Locks in cached chain:");
print_chain_keys_chain(chain);
pr_warn("\nstack backtrace:\n");
dump_stack();
}
#endif
/*
* Checks whether the chain and the current held locks are consistent
* in depth and also in content. If they are not it most likely means
* that there was a collision during the calculation of the chain_key.
* Returns: 0 not passed, 1 passed
*/
static int check_no_collision(struct task_struct *curr,
struct held_lock *hlock,
struct lock_chain *chain)
{
#ifdef CONFIG_DEBUG_LOCKDEP
int i, j, id;
i = get_first_held_lock(curr, hlock);
if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) {
print_collision(curr, hlock, chain);
return 0;
}
for (j = 0; j < chain->depth - 1; j++, i++) {
id = curr->held_locks[i].class_idx - 1;
if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) {
print_collision(curr, hlock, chain);
return 0;
}
}
#endif
return 1;
}
/*
* Given an index that is >= -1, return the index of the next lock chain.
* Return -2 if there is no next lock chain.
*/
long lockdep_next_lockchain(long i)
{
i = find_next_bit(lock_chains_in_use, ARRAY_SIZE(lock_chains), i + 1);
return i < ARRAY_SIZE(lock_chains) ? i : -2;
}
unsigned long lock_chain_count(void)
{
return bitmap_weight(lock_chains_in_use, ARRAY_SIZE(lock_chains));
}
/* Must be called with the graph lock held. */
static struct lock_chain *alloc_lock_chain(void)
{
int idx = find_first_zero_bit(lock_chains_in_use,
ARRAY_SIZE(lock_chains));
if (unlikely(idx >= ARRAY_SIZE(lock_chains)))
return NULL;
__set_bit(idx, lock_chains_in_use);
return lock_chains + idx;
}
/*
* Adds a dependency chain into chain hashtable. And must be called with
* graph_lock held.
*
* Return 0 if fail, and graph_lock is released.
* Return 1 if succeed, with graph_lock held.
*/
static inline int add_chain_cache(struct task_struct *curr,
struct held_lock *hlock,
u64 chain_key)
{
struct lock_class *class = hlock_class(hlock);
struct hlist_head *hash_head = chainhashentry(chain_key);
struct lock_chain *chain;
int i, j;
/*
* The caller must hold the graph lock, ensure we've got IRQs
* disabled to make this an IRQ-safe lock.. for recursion reasons
* lockdep won't complain about its own locking errors.
*/
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
return 0;
chain = alloc_lock_chain();
if (!chain) {
if (!debug_locks_off_graph_unlock())
return 0;
print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
dump_stack();
return 0;
}
chain->chain_key = chain_key;
chain->irq_context = hlock->irq_context;
i = get_first_held_lock(curr, hlock);
chain->depth = curr->lockdep_depth + 1 - i;
BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks));
BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));
if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
chain->base = nr_chain_hlocks;
for (j = 0; j < chain->depth - 1; j++, i++) {
int lock_id = curr->held_locks[i].class_idx - 1;
chain_hlocks[chain->base + j] = lock_id;
}
chain_hlocks[chain->base + j] = class - lock_classes;
nr_chain_hlocks += chain->depth;
} else {
if (!debug_locks_off_graph_unlock())
return 0;
print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
dump_stack();
return 0;
}
hlist_add_head_rcu(&chain->entry, hash_head);
debug_atomic_inc(chain_lookup_misses);
inc_chains();
return 1;
}
/*
* Look up a dependency chain. Must be called with either the graph lock or
* the RCU read lock held.
*/
static inline struct lock_chain *lookup_chain_cache(u64 chain_key)
{
struct hlist_head *hash_head = chainhashentry(chain_key);
struct lock_chain *chain;
hlist_for_each_entry_rcu(chain, hash_head, entry) {
if (READ_ONCE(chain->chain_key) == chain_key) {
debug_atomic_inc(chain_lookup_hits);
return chain;
}
}
return NULL;
}
/*
* If the key is not present yet in dependency chain cache then
* add it and return 1 - in this case the new dependency chain is
* validated. If the key is already hashed, return 0.
* (On return with 1 graph_lock is held.)
*/
static inline int lookup_chain_cache_add(struct task_struct *curr,
struct held_lock *hlock,
u64 chain_key)
{
struct lock_class *class = hlock_class(hlock);
struct lock_chain *chain = lookup_chain_cache(chain_key);
if (chain) {
cache_hit:
if (!check_no_collision(curr, hlock, chain))
return 0;
if (very_verbose(class)) {
printk("\nhash chain already cached, key: "
"%016Lx tail class: [%px] %s\n",
(unsigned long long)chain_key,
class->key, class->name);
}
return 0;
}
if (very_verbose(class)) {
printk("\nnew hash chain, key: %016Lx tail class: [%px] %s\n",
(unsigned long long)chain_key, class->key, class->name);
}
if (!graph_lock())
return 0;
/*
* We have to walk the chain again locked - to avoid duplicates:
*/
chain = lookup_chain_cache(chain_key);
if (chain) {
graph_unlock();
goto cache_hit;
}
if (!add_chain_cache(curr, hlock, chain_key))
return 0;
return 1;
}
static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
struct held_lock *hlock, int chain_head, u64 chain_key)
{
/*
* Trylock needs to maintain the stack of held locks, but it
* does not add new dependencies, because trylock can be done
* in any order.
*
* We look up the chain_key and do the O(N^2) check and update of
* the dependencies only if this is a new dependency chain.
* (If lookup_chain_cache_add() return with 1 it acquires
* graph_lock for us)
*/
if (!hlock->trylock && hlock->check &&
lookup_chain_cache_add(curr, hlock, chain_key)) {
/*
* Check whether last held lock:
*
* - is irq-safe, if this lock is irq-unsafe
* - is softirq-safe, if this lock is hardirq-unsafe
*
* And check whether the new lock's dependency graph
* could lead back to the previous lock.
*
* any of these scenarios could lead to a deadlock. If
* All validations
*/
int ret = check_deadlock(curr, hlock, lock, hlock->read);
if (!ret)
return 0;
/*
* Mark recursive read, as we jump over it when
* building dependencies (just like we jump over
* trylock entries):
*/
if (ret == 2)
hlock->read = 2;
/*
* Add dependency only if this lock is not the head
* of the chain, and if it's not a secondary read-lock:
*/
if (!chain_head && ret != 2) {
if (!check_prevs_add(curr, hlock))
return 0;
}
graph_unlock();
} else {
/* after lookup_chain_cache_add(): */
if (unlikely(!debug_locks))
return 0;
}
return 1;
}
#else
static inline int validate_chain(struct task_struct *curr,
struct lockdep_map *lock, struct held_lock *hlock,
int chain_head, u64 chain_key)
{
return 1;
}
static void print_lock_trace(struct lock_trace *trace, unsigned int spaces)
{
}
#endif
/*
* We are building curr_chain_key incrementally, so double-check
* it from scratch, to make sure that it's done correctly:
*/
static void check_chain_key(struct task_struct *curr)
{
#ifdef CONFIG_DEBUG_LOCKDEP
struct held_lock *hlock, *prev_hlock = NULL;
unsigned int i;
u64 chain_key = 0;
for (i = 0; i < curr->lockdep_depth; i++) {
hlock = curr->held_locks + i;
if (chain_key != hlock->prev_chain_key) {
debug_locks_off();
/*
* We got mighty confused, our chain keys don't match
* with what we expect, someone trample on our task state?
*/
WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
curr->lockdep_depth, i,
(unsigned long long)chain_key,
(unsigned long long)hlock->prev_chain_key);
return;
}
/*
* Whoops ran out of static storage again?
*/
if (DEBUG_LOCKS_WARN_ON(hlock->class_idx > MAX_LOCKDEP_KEYS))
return;
if (prev_hlock && (prev_hlock->irq_context !=
hlock->irq_context))
chain_key = 0;
chain_key = iterate_chain_key(chain_key, hlock->class_idx);
prev_hlock = hlock;
}
if (chain_key != curr->curr_chain_key) {
debug_locks_off();
/*
* More smoking hash instead of calculating it, damn see these
* numbers float.. I bet that a pink elephant stepped on my memory.
*/
WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
curr->lockdep_depth, i,
(unsigned long long)chain_key,
(unsigned long long)curr->curr_chain_key);
}
#endif
}
static int mark_lock(struct task_struct *curr, struct held_lock *this,
enum lock_usage_bit new_bit);
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
static void
print_usage_bug_scenario(struct held_lock *lock)
{
struct lock_class *class = hlock_class(lock);
printk(" Possible unsafe locking scenario:\n\n");
printk(" CPU0\n");
printk(" ----\n");
printk(" lock(");
__print_lock_name(class);
printk(KERN_CONT ");\n");
printk(" <Interrupt>\n");
printk(" lock(");
__print_lock_name(class);
printk(KERN_CONT ");\n");
printk("\n *** DEADLOCK ***\n\n");
}
static int
print_usage_bug(struct task_struct *curr, struct held_lock *this,
enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
{
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
return 0;
pr_warn("\n");
pr_warn("================================\n");
pr_warn("WARNING: inconsistent lock state\n");
print_kernel_ident();
pr_warn("--------------------------------\n");
pr_warn("inconsistent {%s} -> {%s} usage.\n",
usage_str[prev_bit], usage_str[new_bit]);
pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
curr->comm, task_pid_nr(curr),
trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
trace_hardirqs_enabled(curr),
trace_softirqs_enabled(curr));
print_lock(this);
pr_warn("{%s} state was registered at:\n", usage_str[prev_bit]);
print_lock_trace(hlock_class(this)->usage_traces + prev_bit, 1);
print_irqtrace_events(curr);
pr_warn("\nother info that might help us debug this:\n");
print_usage_bug_scenario(this);
lockdep_print_held_locks(curr);
pr_warn("\nstack backtrace:\n");
dump_stack();
return 0;
}
/*
* Print out an error if an invalid bit is set:
*/
static inline int
valid_state(struct task_struct *curr, struct held_lock *this,
enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
{
if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
return print_usage_bug(curr, this, bad_bit, new_bit);
return 1;
}
/*
* print irq inversion bug:
*/
static int
print_irq_inversion_bug(struct task_struct *curr,
struct lock_list *root, struct lock_list *other,
struct held_lock *this, int forwards,
const char *irqclass)
{
struct lock_list *entry = other;
struct lock_list *middle = NULL;
int depth;
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
return 0;
pr_warn("\n");
pr_warn("========================================================\n");
pr_warn("WARNING: possible irq lock inversion dependency detected\n");
print_kernel_ident();
pr_warn("--------------------------------------------------------\n");
pr_warn("%s/%d just changed the state of lock:\n",
curr->comm, task_pid_nr(curr));
print_lock(this);
if (forwards)
pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
else
pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
print_lock_name(other->class);
pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n");
pr_warn("\nother info that might help us debug this:\n");
/* Find a middle lock (if one exists) */
depth = get_lock_depth(other);
do {
if (depth == 0 && (entry != root)) {
pr_warn("lockdep:%s bad path found in chain graph\n", __func__);
break;
}
middle = entry;
entry = get_lock_parent(entry);
depth--;
} while (entry && entry != root && (depth >= 0));
if (forwards)
print_irq_lock_scenario(root, other,
middle ? middle->class : root->class, other->class);
else
print_irq_lock_scenario(other, root,
middle ? middle->class : other->class, root->class);
lockdep_print_held_locks(curr);
pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
if (!save_trace(&root->trace))
return 0;
print_shortest_lock_dependencies(other, root);
pr_warn("\nstack backtrace:\n");
dump_stack();
return 0;
}
/*
* Prove that in the forwards-direction subgraph starting at <this>
* there is no lock matching <mask>:
*/
static int
check_usage_forwards(struct task_struct *curr, struct held_lock *this,
enum lock_usage_bit bit, const char *irqclass)
{
int ret;
struct lock_list root;
struct lock_list *uninitialized_var(target_entry);
root.parent = NULL;
root.class = hlock_class(this);
ret = find_usage_forwards(&root, lock_flag(bit), &target_entry);
if (ret < 0)
return print_bfs_bug(ret);
if (ret == 1)
return ret;
return print_irq_inversion_bug(curr, &root, target_entry,
this, 1, irqclass);
}
/*
* Prove that in the backwards-direction subgraph starting at <this>
* there is no lock matching <mask>:
*/
static int
check_usage_backwards(struct task_struct *curr, struct held_lock *this,
enum lock_usage_bit bit, const char *irqclass)
{
int ret;
struct lock_list root;
struct lock_list *uninitialized_var(target_entry);
root.parent = NULL;
root.class = hlock_class(this);
ret = find_usage_backwards(&root, lock_flag(bit), &target_entry);
if (ret < 0)
return print_bfs_bug(ret);
if (ret == 1)
return ret;
return print_irq_inversion_bug(curr, &root, target_entry,
this, 0, irqclass);
}
void print_irqtrace_events(struct task_struct *curr)
{
printk("irq event stamp: %u\n", curr->irq_events);
printk("hardirqs last enabled at (%u): [<%px>] %pS\n",
curr->hardirq_enable_event, (void *)curr->hardirq_enable_ip,
(void *)curr->hardirq_enable_ip);
printk("hardirqs last disabled at (%u): [<%px>] %pS\n",
curr->hardirq_disable_event, (void *)curr->hardirq_disable_ip,
(void *)curr->hardirq_disable_ip);
printk("softirqs last enabled at (%u): [<%px>] %pS\n",
curr->softirq_enable_event, (void *)curr->softirq_enable_ip,
(void *)curr->softirq_enable_ip);
printk("softirqs last disabled at (%u): [<%px>] %pS\n",
curr->softirq_disable_event, (void *)curr->softirq_disable_ip,
(void *)curr->softirq_disable_ip);
}
static int HARDIRQ_verbose(struct lock_class *class)
{
#if HARDIRQ_VERBOSE
return class_filter(class);
#endif
return 0;
}
static int SOFTIRQ_verbose(struct lock_class *class)
{
#if SOFTIRQ_VERBOSE
return class_filter(class);
#endif
return 0;
}
#define STRICT_READ_CHECKS 1
static int (*state_verbose_f[])(struct lock_class *class) = {
#define LOCKDEP_STATE(__STATE) \
__STATE##_verbose,
#include "lockdep_states.h"
#undef LOCKDEP_STATE
};
static inline int state_verbose(enum lock_usage_bit bit,
struct lock_class *class)
{
return state_verbose_f[bit >> LOCK_USAGE_DIR_MASK](class);
}
typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
enum lock_usage_bit bit, const char *name);
static int
mark_lock_irq(struct task_struct *curr, struct held_lock *this,
enum lock_usage_bit new_bit)
{
int excl_bit = exclusive_bit(new_bit);
int read = new_bit & LOCK_USAGE_READ_MASK;
int dir = new_bit & LOCK_USAGE_DIR_MASK;
/*
* mark USED_IN has to look forwards -- to ensure no dependency
* has ENABLED state, which would allow recursion deadlocks.
*
* mark ENABLED has to look backwards -- to ensure no dependee
* has USED_IN state, which, again, would allow recursion deadlocks.
*/
check_usage_f usage = dir ?
check_usage_backwards : check_usage_forwards;
/*
* Validate that this particular lock does not have conflicting
* usage states.
*/
if (!valid_state(curr, this, new_bit, excl_bit))
return 0;
/*
* Validate that the lock dependencies don't have conflicting usage
* states.
*/
if ((!read || !dir || STRICT_READ_CHECKS) &&
!usage(curr, this, excl_bit, state_name(new_bit & ~LOCK_USAGE_READ_MASK)))
return 0;
/*
* Check for read in write conflicts
*/
if (!read) {
if (!valid_state(curr, this, new_bit, excl_bit + LOCK_USAGE_READ_MASK))
return 0;
if (STRICT_READ_CHECKS &&
!usage(curr, this, excl_bit + LOCK_USAGE_READ_MASK,
state_name(new_bit + LOCK_USAGE_READ_MASK)))
return 0;
}
if (state_verbose(new_bit, hlock_class(this)))
return 2;
return 1;
}
/*
* Mark all held locks with a usage bit:
*/
static int
mark_held_locks(struct task_struct *curr, enum lock_usage_bit base_bit)
{
struct held_lock *hlock;
int i;
for (i = 0; i < curr->lockdep_depth; i++) {
enum lock_usage_bit hlock_bit = base_bit;
hlock = curr->held_locks + i;
if (hlock->read)
hlock_bit += LOCK_USAGE_READ_MASK;
BUG_ON(hlock_bit >= LOCK_USAGE_STATES);
if (!hlock->check)
continue;
if (!mark_lock(curr, hlock, hlock_bit))
return 0;
}
return 1;
}
/*
* Hardirqs will be enabled:
*/
static void __trace_hardirqs_on_caller(unsigned long ip)
{
struct task_struct *curr = current;
/* we'll do an OFF -> ON transition: */
curr->hardirqs_enabled = 1;
/*
* We are going to turn hardirqs on, so set the
* usage bit for all held locks:
*/
if (!mark_held_locks(curr, LOCK_ENABLED_HARDIRQ))
return;
/*
* If we have softirqs enabled, then set the usage
* bit for all held locks. (disabled hardirqs prevented
* this bit from being set before)
*/
if (curr->softirqs_enabled)
if (!mark_held_locks(curr, LOCK_ENABLED_SOFTIRQ))
return;
curr->hardirq_enable_ip = ip;
curr->hardirq_enable_event = ++curr->irq_events;
debug_atomic_inc(hardirqs_on_events);
}
void lockdep_hardirqs_on(unsigned long ip)
{
if (unlikely(!debug_locks || current->lockdep_recursion))
return;
if (unlikely(current->hardirqs_enabled)) {
/*
* Neither irq nor preemption are disabled here
* so this is racy by nature but losing one hit
* in a stat is not a big deal.
*/
__debug_atomic_inc(redundant_hardirqs_on);
return;
}
/*
* We're enabling irqs and according to our state above irqs weren't
* already enabled, yet we find the hardware thinks they are in fact
* enabled.. someone messed up their IRQ state tracing.
*/
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
return;
/*
* See the fine text that goes along with this variable definition.
*/
if (DEBUG_LOCKS_WARN_ON(early_boot_irqs_disabled))
return;
/*
* Can't allow enabling interrupts while in an interrupt handler,
* that's general bad form and such. Recursion, limited stack etc..
*/
if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
return;
current->lockdep_recursion = 1;
__trace_hardirqs_on_caller(ip);
current->lockdep_recursion = 0;
}
NOKPROBE_SYMBOL(lockdep_hardirqs_on);
/*
* Hardirqs were disabled:
*/
void lockdep_hardirqs_off(unsigned long ip)
{
struct task_struct *curr = current;
if (unlikely(!debug_locks || current->lockdep_recursion))
return;
/*
* So we're supposed to get called after you mask local IRQs, but for
* some reason the hardware doesn't quite think you did a proper job.
*/
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
return;
if (curr->hardirqs_enabled) {
/*
* We have done an ON -> OFF transition:
*/
curr->hardirqs_enabled = 0;
curr->hardirq_disable_ip = ip;
curr->hardirq_disable_event = ++curr->irq_events;
debug_atomic_inc(hardirqs_off_events);
} else
debug_atomic_inc(redundant_hardirqs_off);
}
NOKPROBE_SYMBOL(lockdep_hardirqs_off);
/*
* Softirqs will be enabled:
*/
void trace_softirqs_on(unsigned long ip)
{
struct task_struct *curr = current;
if (unlikely(!debug_locks || current->lockdep_recursion))
return;
/*
* We fancy IRQs being disabled here, see softirq.c, avoids
* funny state and nesting things.
*/
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
return;
if (curr->softirqs_enabled) {
debug_atomic_inc(redundant_softirqs_on);
return;
}
current->lockdep_recursion = 1;
/*
* We'll do an OFF -> ON transition:
*/
curr->softirqs_enabled = 1;
curr->softirq_enable_ip = ip;
curr->softirq_enable_event = ++curr->irq_events;
debug_atomic_inc(softirqs_on_events);
/*
* We are going to turn softirqs on, so set the
* usage bit for all held locks, if hardirqs are
* enabled too:
*/
if (curr->hardirqs_enabled)
mark_held_locks(curr, LOCK_ENABLED_SOFTIRQ);
current->lockdep_recursion = 0;
}
/*
* Softirqs were disabled:
*/
void trace_softirqs_off(unsigned long ip)
{
struct task_struct *curr = current;
if (unlikely(!debug_locks || current->lockdep_recursion))
return;
/*
* We fancy IRQs being disabled here, see softirq.c
*/
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
return;
if (curr->softirqs_enabled) {
/*
* We have done an ON -> OFF transition:
*/
curr->softirqs_enabled = 0;
curr->softirq_disable_ip = ip;
curr->softirq_disable_event = ++curr->irq_events;
debug_atomic_inc(softirqs_off_events);
/*
* Whoops, we wanted softirqs off, so why aren't they?
*/
DEBUG_LOCKS_WARN_ON(!softirq_count());
} else
debug_atomic_inc(redundant_softirqs_off);
}
static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
{
/*
* If non-trylock use in a hardirq or softirq context, then
* mark the lock as used in these contexts:
*/
if (!hlock->trylock) {
if (hlock->read) {
if (curr->hardirq_context)
if (!mark_lock(curr, hlock,
LOCK_USED_IN_HARDIRQ_READ))
return 0;
if (curr->softirq_context)
if (!mark_lock(curr, hlock,
LOCK_USED_IN_SOFTIRQ_READ))
return 0;
} else {
if (curr->hardirq_context)
if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
return 0;
if (curr->softirq_context)
if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
return 0;
}
}
if (!hlock->hardirqs_off) {
if (hlock->read) {
if (!mark_lock(curr, hlock,
LOCK_ENABLED_HARDIRQ_READ))
return 0;
if (curr->softirqs_enabled)
if (!mark_lock(curr, hlock,
LOCK_ENABLED_SOFTIRQ_READ))
return 0;
} else {
if (!mark_lock(curr, hlock,
LOCK_ENABLED_HARDIRQ))
return 0;
if (curr->softirqs_enabled)
if (!mark_lock(curr, hlock,
LOCK_ENABLED_SOFTIRQ))
return 0;
}
}
return 1;
}
static inline unsigned int task_irq_context(struct task_struct *task)
{
return 2 * !!task->hardirq_context + !!task->softirq_context;
}
static int separate_irq_context(struct task_struct *curr,
struct held_lock *hlock)
{
unsigned int depth = curr->lockdep_depth;
/*
* Keep track of points where we cross into an interrupt context:
*/
if (depth) {
struct held_lock *prev_hlock;
prev_hlock = curr->held_locks + depth-1;
/*
* If we cross into another context, reset the
* hash key (this also prevents the checking and the
* adding of the dependency to 'prev'):
*/
if (prev_hlock->irq_context != hlock->irq_context)
return 1;
}
return 0;
}
#else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
static inline
int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
enum lock_usage_bit new_bit)
{
WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
return 1;
}
static inline int mark_irqflags(struct task_struct *curr,
struct held_lock *hlock)
{
return 1;
}
static inline unsigned int task_irq_context(struct task_struct *task)
{
return 0;
}
static inline int separate_irq_context(struct task_struct *curr,
struct held_lock *hlock)
{
return 0;
}
#endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
/*
* Mark a lock with a usage bit, and validate the state transition:
*/
static int mark_lock(struct task_struct *curr, struct held_lock *this,
enum lock_usage_bit new_bit)
{
unsigned int new_mask = 1 << new_bit, ret = 1;
/*
* If already set then do not dirty the cacheline,
* nor do any checks:
*/
if (likely(hlock_class(this)->usage_mask & new_mask))
return 1;
if (!graph_lock())
return 0;
/*
* Make sure we didn't race:
*/
if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
graph_unlock();
return 1;
}
hlock_class(this)->usage_mask |= new_mask;
if (!save_trace(hlock_class(this)->usage_traces + new_bit))
return 0;
switch (new_bit) {
#define LOCKDEP_STATE(__STATE) \
case LOCK_USED_IN_##__STATE: \
case LOCK_USED_IN_##__STATE##_READ: \
case LOCK_ENABLED_##__STATE: \
case LOCK_ENABLED_##__STATE##_READ:
#include "lockdep_states.h"
#undef LOCKDEP_STATE
ret = mark_lock_irq(curr, this, new_bit);
if (!ret)
return 0;
break;
case LOCK_USED:
debug_atomic_dec(nr_unused_locks);
break;
default:
if (!debug_locks_off_graph_unlock())
return 0;
WARN_ON(1);
return 0;
}
graph_unlock();
/*
* We must printk outside of the graph_lock:
*/
if (ret == 2) {
printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
print_lock(this);
print_irqtrace_events(curr);
dump_stack();
}
return ret;
}
/*
* Initialize a lock instance's lock-class mapping info:
*/
void lockdep_init_map(struct lockdep_map *lock, const char *name,
struct lock_class_key *key, int subclass)
{
int i;
for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
lock->class_cache[i] = NULL;
#ifdef CONFIG_LOCK_STAT
lock->cpu = raw_smp_processor_id();
#endif
/*
* Can't be having no nameless bastards around this place!
*/
if (DEBUG_LOCKS_WARN_ON(!name)) {
lock->name = "NULL";
return;
}
lock->name = name;
/*
* No key, no joy, we need to hash something.
*/
if (DEBUG_LOCKS_WARN_ON(!key))
return;
/*
* Sanity check, the lock-class key must either have been allocated
* statically or must have been registered as a dynamic key.
*/
if (!static_obj(key) && !is_dynamic_key(key)) {
if (debug_locks)
printk(KERN_ERR "BUG: key %px has not been registered!\n", key);
DEBUG_LOCKS_WARN_ON(1);
return;
}
lock->key = key;
if (unlikely(!debug_locks))
return;
if (subclass) {
unsigned long flags;
if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion))
return;
raw_local_irq_save(flags);
current->lockdep_recursion = 1;
register_lock_class(lock, subclass, 1);
current->lockdep_recursion = 0;
raw_local_irq_restore(flags);
}
}
EXPORT_SYMBOL_GPL(lockdep_init_map);
struct lock_class_key __lockdep_no_validate__;
EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
static int
print_lock_nested_lock_not_held(struct task_struct *curr,
struct held_lock *hlock,
unsigned long ip)
{
if (!debug_locks_off())
return 0;
if (debug_locks_silent)
return 0;
pr_warn("\n");
pr_warn("==================================\n");
pr_warn("WARNING: Nested lock was not taken\n");
print_kernel_ident();
pr_warn("----------------------------------\n");
pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
print_lock(hlock);
pr_warn("\nbut this task is not holding:\n");
pr_warn("%s\n", hlock->nest_lock->name);
pr_warn("\nstack backtrace:\n");
dump_stack();
pr_warn("\nother info that might help us debug this:\n");
lockdep_print_held_locks(curr);
pr_warn("\nstack backtrace:\n");
dump_stack();
return 0;
}
static int __lock_is_held(const struct lockdep_map *lock, int read);
/*
* This gets called for every mutex_lock*()/spin_lock*() operation.
* We maintain the dependency maps and validate the locking attempt:
*
* The callers must make sure that IRQs are disabled before calling it,
* otherwise we could get an interrupt which would want to take locks,
* which would end up in lockdep again.
*/
static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
int trylock, int read, int check, int hardirqs_off,
struct lockdep_map *nest_lock, unsigned long ip,
int references, int pin_count)
{
struct task_struct *curr = current;
struct lock_class *class = NULL;
struct held_lock *hlock;
unsigned int depth;
int chain_head = 0;
int class_idx;
u64 chain_key;
if (unlikely(!debug_locks))
return 0;
if (!prove_locking || lock->key == &__lockdep_no_validate__)
check = 0;
if (subclass < NR_LOCKDEP_CACHING_CLASSES)
class = lock->class_cache[subclass];
/*
* Not cached?
*/
if (unlikely(!class)) {
class = register_lock_class(lock, subclass, 0);
if (!class)
return 0;
}
debug_class_ops_inc(class);
if (very_verbose(class)) {
printk("\nacquire class [%px] %s", class->key, class->name);
if (class->name_version > 1)
printk(KERN_CONT "#%d", class->name_version);
printk(KERN_CONT "\n");
dump_stack();
}
/*
* Add the lock to the list of currently held locks.
* (we dont increase the depth just yet, up until the
* dependency checks are done)
*/
depth = curr->lockdep_depth;
/*
* Ran out of static storage for our per-task lock stack again have we?
*/
if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
return 0;
class_idx = class - lock_classes + 1;
if (depth) {
hlock = curr->held_locks + depth - 1;
if (hlock->class_idx == class_idx && nest_lock) {
if (hlock->references) {
/*
* Check: unsigned int references:12, overflow.
*/
if (DEBUG_LOCKS_WARN_ON(hlock->references == (1 << 12)-1))
return 0;
hlock->references++;
} else {
hlock->references = 2;
}
return 1;
}
}
hlock = curr->held_locks + depth;
/*
* Plain impossible, we just registered it and checked it weren't no
* NULL like.. I bet this mushroom I ate was good!
*/
if (DEBUG_LOCKS_WARN_ON(!class))
return 0;
hlock->class_idx = class_idx;
hlock->acquire_ip = ip;
hlock->instance = lock;
hlock->nest_lock = nest_lock;
hlock->irq_context = task_irq_context(curr);
hlock->trylock = trylock;
hlock->read = read;
hlock->check = check;
hlock->hardirqs_off = !!hardirqs_off;
hlock->references = references;
#ifdef CONFIG_LOCK_STAT
hlock->waittime_stamp = 0;
hlock->holdtime_stamp = lockstat_clock();
#endif
hlock->pin_count = pin_count;
if (check && !mark_irqflags(curr, hlock))
return 0;
/* mark it as used: */
if (!mark_lock(curr, hlock, LOCK_USED))
return 0;
/*
* Calculate the chain hash: it's the combined hash of all the
* lock keys along the dependency chain. We save the hash value
* at every step so that we can get the current hash easily
* after unlock. The chain hash is then used to cache dependency
* results.
*
* The 'key ID' is what is the most compact key value to drive
* the hash, not class->key.
*/
/*
* Whoops, we did it again.. ran straight out of our static allocation.
*/
if (DEBUG_LOCKS_WARN_ON(class_idx > MAX_LOCKDEP_KEYS))
return 0;
chain_key = curr->curr_chain_key;
if (!depth) {
/*
* How can we have a chain hash when we ain't got no keys?!
*/
if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
return 0;
chain_head = 1;
}
hlock->prev_chain_key = chain_key;
if (separate_irq_context(curr, hlock)) {
chain_key = 0;
chain_head = 1;
}
chain_key = iterate_chain_key(chain_key, class_idx);
if (nest_lock && !__lock_is_held(nest_lock, -1))
return print_lock_nested_lock_not_held(curr, hlock, ip);
if (!debug_locks_silent) {
WARN_ON_ONCE(depth && !hlock_class(hlock - 1)->key);
WARN_ON_ONCE(!hlock_class(hlock)->key);
}
if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
return 0;
curr->curr_chain_key = chain_key;
curr->lockdep_depth++;
check_chain_key(curr);
#ifdef CONFIG_DEBUG_LOCKDEP
if (unlikely(!debug_locks))
return 0;
#endif
if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
debug_locks_off();
print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
printk(KERN_DEBUG "depth: %i max: %lu!\n",
curr->lockdep_depth, MAX_LOCK_DEPTH);
lockdep_print_held_locks(current);
debug_show_all_locks();
dump_stack();
return 0;
}
if (unlikely(curr->lockdep_depth > max_lockdep_depth))
max_lockdep_depth = curr->lockdep_depth;
return 1;
}
static int
print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
unsigned long ip)
{
if (!debug_locks_off())
return 0;
if (debug_locks_silent)
return 0;
pr_warn("\n");
pr_warn("=====================================\n");
pr_warn("WARNING: bad unlock balance detected!\n");
print_kernel_ident();
pr_warn("-------------------------------------\n");
pr_warn("%s/%d is trying to release lock (",
curr->comm, task_pid_nr(curr));
print_lockdep_cache(lock);
pr_cont(") at:\n");
print_ip_sym(ip);
pr_warn("but there are no more locks to release!\n");
pr_warn("\nother info that might help us debug this:\n");
lockdep_print_held_locks(curr);
pr_warn("\nstack backtrace:\n");
dump_stack();
return 0;
}
static int match_held_lock(const struct held_lock *hlock,
const struct lockdep_map *lock)
{
if (hlock->instance == lock)
return 1;
if (hlock->references) {
const struct lock_class *class = lock->class_cache[0];
if (!class)
class = look_up_lock_class(lock, 0);
/*
* If look_up_lock_class() failed to find a class, we're trying
* to test if we hold a lock that has never yet been acquired.
* Clearly if the lock hasn't been acquired _ever_, we're not
* holding it either, so report failure.
*/
if (!class)
return 0;
/*
* References, but not a lock we're actually ref-counting?
* State got messed up, follow the sites that change ->references
* and try to make sense of it.
*/
if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
return 0;
if (hlock->class_idx == class - lock_classes + 1)
return 1;
}
return 0;
}
/* @depth must not be zero */
static struct held_lock *find_held_lock(struct task_struct *curr,
struct lockdep_map *lock,
unsigned int depth, int *idx)
{
struct held_lock *ret, *hlock, *prev_hlock;
int i;
i = depth - 1;
hlock = curr->held_locks + i;
ret = hlock;
if (match_held_lock(hlock, lock))
goto out;
ret = NULL;
for (i--, prev_hlock = hlock--;
i >= 0;
i--, prev_hlock = hlock--) {
/*
* We must not cross into another context:
*/
if (prev_hlock->irq_context != hlock->irq_context) {
ret = NULL;
break;
}
if (match_held_lock(hlock, lock)) {
ret = hlock;
break;
}
}
out:
*idx = i;
return ret;
}
static int reacquire_held_locks(struct task_struct *curr, unsigned int depth,
int idx)
{
struct held_lock *hlock;
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
return 0;
for (hlock = curr->held_locks + idx; idx < depth; idx++, hlock++) {
if (!__lock_acquire(hlock->instance,
hlock_class(hlock)->subclass,
hlock->trylock,
hlock->read, hlock->check,
hlock->hardirqs_off,
hlock->nest_lock, hlock->acquire_ip,
hlock->references, hlock->pin_count))
return 1;
}
return 0;
}
static int
__lock_set_class(struct lockdep_map *lock, const char *name,
struct lock_class_key *key, unsigned int subclass,
unsigned long ip)
{
struct task_struct *curr = current;
struct held_lock *hlock;
struct lock_class *class;
unsigned int depth;
int i;
if (unlikely(!debug_locks))
return 0;
depth = curr->lockdep_depth;
/*
* This function is about (re)setting the class of a held lock,
* yet we're not actually holding any locks. Naughty user!
*/
if (DEBUG_LOCKS_WARN_ON(!depth))
return 0;
hlock = find_held_lock(curr, lock, depth, &i);
if (!hlock)
return print_unlock_imbalance_bug(curr, lock, ip);
lockdep_init_map(lock, name, key, 0);
class = register_lock_class(lock, subclass, 0);
hlock->class_idx = class - lock_classes + 1;
curr->lockdep_depth = i;
curr->curr_chain_key = hlock->prev_chain_key;
if (reacquire_held_locks(curr, depth, i))
return 0;
/*
* I took it apart and put it back together again, except now I have
* these 'spare' parts.. where shall I put them.
*/
if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
return 0;
return 1;
}
static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip)
{
struct task_struct *curr = current;
struct held_lock *hlock;
unsigned int depth;
int i;
if (unlikely(!debug_locks))
return 0;
depth = curr->lockdep_depth;
/*
* This function is about (re)setting the class of a held lock,
* yet we're not actually holding any locks. Naughty user!
*/
if (DEBUG_LOCKS_WARN_ON(!depth))
return 0;
hlock = find_held_lock(curr, lock, depth, &i);
if (!hlock)
return print_unlock_imbalance_bug(curr, lock, ip);
curr->lockdep_depth = i;
curr->curr_chain_key = hlock->prev_chain_key;
WARN(hlock->read, "downgrading a read lock");
hlock->read = 1;
hlock->acquire_ip = ip;
if (reacquire_held_locks(curr, depth, i))
return 0;
/*
* I took it apart and put it back together again, except now I have
* these 'spare' parts.. where shall I put them.
*/
if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
return 0;
return 1;
}
/*
* Remove the lock to the list of currently held locks - this gets
* called on mutex_unlock()/spin_unlock*() (or on a failed
* mutex_lock_interruptible()).
*
* @nested is an hysterical artifact, needs a tree wide cleanup.
*/
static int
__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
{
struct task_struct *curr = current;
struct held_lock *hlock;
unsigned int depth;
int i;
if (unlikely(!debug_locks))
return 0;
depth = curr->lockdep_depth;
/*
* So we're all set to release this lock.. wait what lock? We don't
* own any locks, you've been drinking again?
*/
if (DEBUG_LOCKS_WARN_ON(depth <= 0))
return print_unlock_imbalance_bug(curr, lock, ip);
/*
* Check whether the lock exists in the current stack
* of held locks:
*/
hlock = find_held_lock(curr, lock, depth, &i);
if (!hlock)
return print_unlock_imbalance_bug(curr, lock, ip);
if (hlock->instance == lock)
lock_release_holdtime(hlock);
WARN(hlock->pin_count, "releasing a pinned lock\n");
if (hlock->references) {
hlock->references--;
if (hlock->references) {
/*
* We had, and after removing one, still have
* references, the current lock stack is still
* valid. We're done!
*/
return 1;
}
}
/*
* We have the right lock to unlock, 'hlock' points to it.
* Now we remove it from the stack, and add back the other
* entries (if any), recalculating the hash along the way:
*/
curr->lockdep_depth = i;
curr->curr_chain_key = hlock->prev_chain_key;
/*
* The most likely case is when the unlock is on the innermost
* lock. In this case, we are done!
*/
if (i == depth-1)
return 1;
if (reacquire_held_locks(curr, depth, i + 1))
return 0;
/*
* We had N bottles of beer on the wall, we drank one, but now
* there's not N-1 bottles of beer left on the wall...
*/
DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth-1);
/*
* Since reacquire_held_locks() would have called check_chain_key()
* indirectly via __lock_acquire(), we don't need to do it again
* on return.
*/
return 0;
}
static nokprobe_inline
int __lock_is_held(const struct lockdep_map *lock, int read)
{
struct task_struct *curr = current;
int i;
for (i = 0; i < curr->lockdep_depth; i++) {
struct held_lock *hlock = curr->held_locks + i;
if (match_held_lock(hlock, lock)) {
if (read == -1 || hlock->read == read)
return 1;
return 0;
}
}
return 0;
}
static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock)
{
struct pin_cookie cookie = NIL_COOKIE;
struct task_struct *curr = current;
int i;
if (unlikely(!debug_locks))
return cookie;
for (i = 0; i < curr->lockdep_depth; i++) {
struct held_lock *hlock = curr->held_locks + i;
if (match_held_lock(hlock, lock)) {
/*
* Grab 16bits of randomness; this is sufficient to not
* be guessable and still allows some pin nesting in
* our u32 pin_count.
*/
cookie.val = 1 + (prandom_u32() >> 16);
hlock->pin_count += cookie.val;
return cookie;
}
}
WARN(1, "pinning an unheld lock\n");
return cookie;
}
static void __lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
{
struct task_struct *curr = current;
int i;
if (unlikely(!debug_locks))
return;
for (i = 0; i < curr->lockdep_depth; i++) {
struct held_lock *hlock = curr->held_locks + i;
if (match_held_lock(hlock, lock)) {
hlock->pin_count += cookie.val;
return;
}
}
WARN(1, "pinning an unheld lock\n");
}
static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
{
struct task_struct *curr = current;
int i;
if (unlikely(!debug_locks))
return;
for (i = 0; i < curr->lockdep_depth; i++) {
struct held_lock *hlock = curr->held_locks + i;
if (match_held_lock(hlock, lock)) {
if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n"))
return;
hlock->pin_count -= cookie.val;
if (WARN((int)hlock->pin_count < 0, "pin count corrupted\n"))
hlock->pin_count = 0;
return;
}
}
WARN(1, "unpinning an unheld lock\n");
}
/*
* Check whether we follow the irq-flags state precisely:
*/
static void check_flags(unsigned long flags)
{
#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
defined(CONFIG_TRACE_IRQFLAGS)
if (!debug_locks)
return;
if (irqs_disabled_flags(flags)) {
if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
printk("possible reason: unannotated irqs-off.\n");
}
} else {
if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
printk("possible reason: unannotated irqs-on.\n");
}
}
/*
* We dont accurately track softirq state in e.g.
* hardirq contexts (such as on 4KSTACKS), so only
* check if not in hardirq contexts:
*/
if (!hardirq_count()) {
if (softirq_count()) {
/* like the above, but with softirqs */
DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
} else {
/* lick the above, does it taste good? */
DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
}
}
if (!debug_locks)
print_irqtrace_events(current);
#endif
}
void lock_set_class(struct lockdep_map *lock, const char *name,
struct lock_class_key *key, unsigned int subclass,
unsigned long ip)
{
unsigned long flags;
if (unlikely(current->lockdep_recursion))
return;
raw_local_irq_save(flags);
current->lockdep_recursion = 1;
check_flags(flags);
if (__lock_set_class(lock, name, key, subclass, ip))
check_chain_key(current);
current->lockdep_recursion = 0;
raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_set_class);
void lock_downgrade(struct lockdep_map *lock, unsigned long ip)
{
unsigned long flags;
if (unlikely(current->lockdep_recursion))
return;
raw_local_irq_save(flags);
current->lockdep_recursion = 1;
check_flags(flags);
if (__lock_downgrade(lock, ip))
check_chain_key(current);
current->lockdep_recursion = 0;
raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_downgrade);
/*
* We are not always called with irqs disabled - do that here,
* and also avoid lockdep recursion:
*/
void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
int trylock, int read, int check,
struct lockdep_map *nest_lock, unsigned long ip)
{
unsigned long flags;
if (unlikely(current->lockdep_recursion))
return;
raw_local_irq_save(flags);
check_flags(flags);
current->lockdep_recursion = 1;
trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
__lock_acquire(lock, subclass, trylock, read, check,
irqs_disabled_flags(flags), nest_lock, ip, 0, 0);
current->lockdep_recursion = 0;
raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_acquire);
void lock_release(struct lockdep_map *lock, int nested,
unsigned long ip)
{
unsigned long flags;
if (unlikely(current->lockdep_recursion))
return;
raw_local_irq_save(flags);
check_flags(flags);
current->lockdep_recursion = 1;
trace_lock_release(lock, ip);
if (__lock_release(lock, nested, ip))
check_chain_key(current);
current->lockdep_recursion = 0;
raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_release);
int lock_is_held_type(const struct lockdep_map *lock, int read)
{
unsigned long flags;
int ret = 0;
if (unlikely(current->lockdep_recursion))
return 1; /* avoid false negative lockdep_assert_held() */
raw_local_irq_save(flags);
check_flags(flags);
current->lockdep_recursion = 1;
ret = __lock_is_held(lock, read);
current->lockdep_recursion = 0;
raw_local_irq_restore(flags);
return ret;
}
EXPORT_SYMBOL_GPL(lock_is_held_type);
NOKPROBE_SYMBOL(lock_is_held_type);
struct pin_cookie lock_pin_lock(struct lockdep_map *lock)
{
struct pin_cookie cookie = NIL_COOKIE;
unsigned long flags;
if (unlikely(current->lockdep_recursion))
return cookie;
raw_local_irq_save(flags);
check_flags(flags);
current->lockdep_recursion = 1;
cookie = __lock_pin_lock(lock);
current->lockdep_recursion = 0;
raw_local_irq_restore(flags);
return cookie;
}
EXPORT_SYMBOL_GPL(lock_pin_lock);
void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
{
unsigned long flags;
if (unlikely(current->lockdep_recursion))
return;
raw_local_irq_save(flags);
check_flags(flags);
current->lockdep_recursion = 1;
__lock_repin_lock(lock, cookie);
current->lockdep_recursion = 0;
raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_repin_lock);
void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
{
unsigned long flags;
if (unlikely(current->lockdep_recursion))
return;
raw_local_irq_save(flags);
check_flags(flags);
current->lockdep_recursion = 1;
__lock_unpin_lock(lock, cookie);
current->lockdep_recursion = 0;
raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_unpin_lock);
#ifdef CONFIG_LOCK_STAT
static int
print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
unsigned long ip)
{
if (!debug_locks_off())
return 0;
if (debug_locks_silent)
return 0;
pr_warn("\n");
pr_warn("=================================\n");
pr_warn("WARNING: bad contention detected!\n");
print_kernel_ident();
pr_warn("---------------------------------\n");
pr_warn("%s/%d is trying to contend lock (",
curr->comm, task_pid_nr(curr));
print_lockdep_cache(lock);
pr_cont(") at:\n");
print_ip_sym(ip);
pr_warn("but there are no locks held!\n");
pr_warn("\nother info that might help us debug this:\n");
lockdep_print_held_locks(curr);
pr_warn("\nstack backtrace:\n");
dump_stack();
return 0;
}
static void
__lock_contended(struct lockdep_map *lock, unsigned long ip)
{
struct task_struct *curr = current;
struct held_lock *hlock;
struct lock_class_stats *stats;
unsigned int depth;
int i, contention_point, contending_point;
depth = curr->lockdep_depth;
/*
* Whee, we contended on this lock, except it seems we're not
* actually trying to acquire anything much at all..
*/
if (DEBUG_LOCKS_WARN_ON(!depth))
return;
hlock = find_held_lock(curr, lock, depth, &i);
if (!hlock) {
print_lock_contention_bug(curr, lock, ip);
return;
}
if (hlock->instance != lock)
return;
hlock->waittime_stamp = lockstat_clock();
contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
contending_point = lock_point(hlock_class(hlock)->contending_point,
lock->ip);
stats = get_lock_stats(hlock_class(hlock));
if (contention_point < LOCKSTAT_POINTS)
stats->contention_point[contention_point]++;
if (contending_point < LOCKSTAT_POINTS)
stats->contending_point[contending_point]++;
if (lock->cpu != smp_processor_id())
stats->bounces[bounce_contended + !!hlock->read]++;
}
static void
__lock_acquired(struct lockdep_map *lock, unsigned long ip)
{
struct task_struct *curr = current;
struct held_lock *hlock;
struct lock_class_stats *stats;
unsigned int depth;
u64 now, waittime = 0;
int i, cpu;
depth = curr->lockdep_depth;
/*
* Yay, we acquired ownership of this lock we didn't try to
* acquire, how the heck did that happen?
*/
if (DEBUG_LOCKS_WARN_ON(!depth))
return;
hlock = find_held_lock(curr, lock, depth, &i);
if (!hlock) {
print_lock_contention_bug(curr, lock, _RET_IP_);
return;
}
if (hlock->instance != lock)
return;
cpu = smp_processor_id();
if (hlock->waittime_stamp) {
now = lockstat_clock();
waittime = now - hlock->waittime_stamp;
hlock->holdtime_stamp = now;
}
trace_lock_acquired(lock, ip);
stats = get_lock_stats(hlock_class(hlock));
if (waittime) {
if (hlock->read)
lock_time_inc(&stats->read_waittime, waittime);
else
lock_time_inc(&stats->write_waittime, waittime);
}
if (lock->cpu != cpu)
stats->bounces[bounce_acquired + !!hlock->read]++;
lock->cpu = cpu;
lock->ip = ip;
}
void lock_contended(struct lockdep_map *lock, unsigned long ip)
{
unsigned long flags;
if (unlikely(!lock_stat || !debug_locks))
return;
if (unlikely(current->lockdep_recursion))
return;
raw_local_irq_save(flags);
check_flags(flags);
current->lockdep_recursion = 1;
trace_lock_contended(lock, ip);
__lock_contended(lock, ip);
current->lockdep_recursion = 0;
raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_contended);
void lock_acquired(struct lockdep_map *lock, unsigned long ip)
{
unsigned long flags;
if (unlikely(!lock_stat || !debug_locks))
return;
if (unlikely(current->lockdep_recursion))
return;
raw_local_irq_save(flags);
check_flags(flags);
current->lockdep_recursion = 1;
__lock_acquired(lock, ip);
current->lockdep_recursion = 0;
raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(lock_acquired);
#endif
/*
* Used by the testsuite, sanitize the validator state
* after a simulated failure:
*/
void lockdep_reset(void)
{
unsigned long flags;
int i;
raw_local_irq_save(flags);
current->curr_chain_key = 0;
current->lockdep_depth = 0;
current->lockdep_recursion = 0;
memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
nr_hardirq_chains = 0;
nr_softirq_chains = 0;
nr_process_chains = 0;
debug_locks = 1;
for (i = 0; i < CHAINHASH_SIZE; i++)
INIT_HLIST_HEAD(chainhash_table + i);
raw_local_irq_restore(flags);
}
/* Remove a class from a lock chain. Must be called with the graph lock held. */
static void remove_class_from_lock_chain(struct pending_free *pf,
struct lock_chain *chain,
struct lock_class *class)
{
#ifdef CONFIG_PROVE_LOCKING
struct lock_chain *new_chain;
u64 chain_key;
int i;
for (i = chain->base; i < chain->base + chain->depth; i++) {
if (chain_hlocks[i] != class - lock_classes)
continue;
/* The code below leaks one chain_hlock[] entry. */
if (--chain->depth > 0) {
memmove(&chain_hlocks[i], &chain_hlocks[i + 1],
(chain->base + chain->depth - i) *
sizeof(chain_hlocks[0]));
}
/*
* Each lock class occurs at most once in a lock chain so once
* we found a match we can break out of this loop.
*/
goto recalc;
}
/* Since the chain has not been modified, return. */
return;
recalc:
chain_key = 0;
for (i = chain->base; i < chain->base + chain->depth; i++)
chain_key = iterate_chain_key(chain_key, chain_hlocks[i] + 1);
if (chain->depth && chain->chain_key == chain_key)
return;
/* Overwrite the chain key for concurrent RCU readers. */
WRITE_ONCE(chain->chain_key, chain_key);
/*
* Note: calling hlist_del_rcu() from inside a
* hlist_for_each_entry_rcu() loop is safe.
*/
hlist_del_rcu(&chain->entry);
__set_bit(chain - lock_chains, pf->lock_chains_being_freed);
if (chain->depth == 0)
return;
/*
* If the modified lock chain matches an existing lock chain, drop
* the modified lock chain.
*/
if (lookup_chain_cache(chain_key))
return;
new_chain = alloc_lock_chain();
if (WARN_ON_ONCE(!new_chain)) {
debug_locks_off();
return;
}
*new_chain = *chain;
hlist_add_head_rcu(&new_chain->entry, chainhashentry(chain_key));
#endif
}
/* Must be called with the graph lock held. */
static void remove_class_from_lock_chains(struct pending_free *pf,
struct lock_class *class)
{
struct lock_chain *chain;
struct hlist_head *head;
int i;
for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) {
head = chainhash_table + i;
hlist_for_each_entry_rcu(chain, head, entry) {
remove_class_from_lock_chain(pf, chain, class);
}
}
}
/*
* Remove all references to a lock class. The caller must hold the graph lock.
*/
static void zap_class(struct pending_free *pf, struct lock_class *class)
{
struct lock_list *entry;
int i;
WARN_ON_ONCE(!class->key);
/*
* Remove all dependencies this lock is
* involved in:
*/
for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
entry = list_entries + i;
if (entry->class != class && entry->links_to != class)
continue;
__clear_bit(i, list_entries_in_use);
nr_list_entries--;
list_del_rcu(&entry->entry);
}
if (list_empty(&class->locks_after) &&
list_empty(&class->locks_before)) {
list_move_tail(&class->lock_entry, &pf->zapped);
hlist_del_rcu(&class->hash_entry);
WRITE_ONCE(class->key, NULL);
WRITE_ONCE(class->name, NULL);
nr_lock_classes--;
} else {
WARN_ONCE(true, "%s() failed for class %s\n", __func__,
class->name);
}
remove_class_from_lock_chains(pf, class);
}
static void reinit_class(struct lock_class *class)
{
void *const p = class;
const unsigned int offset = offsetof(struct lock_class, key);
WARN_ON_ONCE(!class->lock_entry.next);
WARN_ON_ONCE(!list_empty(&class->locks_after));
WARN_ON_ONCE(!list_empty(&class->locks_before));
memset(p + offset, 0, sizeof(*class) - offset);
WARN_ON_ONCE(!class->lock_entry.next);
WARN_ON_ONCE(!list_empty(&class->locks_after));
WARN_ON_ONCE(!list_empty(&class->locks_before));
}
static inline int within(const void *addr, void *start, unsigned long size)
{
return addr >= start && addr < start + size;
}
static bool inside_selftest(void)
{
return current == lockdep_selftest_task_struct;
}
/* The caller must hold the graph lock. */
static struct pending_free *get_pending_free(void)
{
return delayed_free.pf + delayed_free.index;
}
static void free_zapped_rcu(struct rcu_head *cb);
/*
* Schedule an RCU callback if no RCU callback is pending. Must be called with
* the graph lock held.
*/
static void call_rcu_zapped(struct pending_free *pf)
{
WARN_ON_ONCE(inside_selftest());
if (list_empty(&pf->zapped))
return;
if (delayed_free.scheduled)
return;
delayed_free.scheduled = true;
WARN_ON_ONCE(delayed_free.pf + delayed_free.index != pf);
delayed_free.index ^= 1;
call_rcu(&delayed_free.rcu_head, free_zapped_rcu);
}
/* The caller must hold the graph lock. May be called from RCU context. */
static void __free_zapped_classes(struct pending_free *pf)
{
struct lock_class *class;
check_data_structures();
list_for_each_entry(class, &pf->zapped, lock_entry)
reinit_class(class);
list_splice_init(&pf->zapped, &free_lock_classes);
#ifdef CONFIG_PROVE_LOCKING
bitmap_andnot(lock_chains_in_use, lock_chains_in_use,
pf->lock_chains_being_freed, ARRAY_SIZE(lock_chains));
bitmap_clear(pf->lock_chains_being_freed, 0, ARRAY_SIZE(lock_chains));
#endif
}
static void free_zapped_rcu(struct rcu_head *ch)
{
struct pending_free *pf;
unsigned long flags;
if (WARN_ON_ONCE(ch != &delayed_free.rcu_head))
return;
raw_local_irq_save(flags);
arch_spin_lock(&lockdep_lock);
current->lockdep_recursion = 1;
/* closed head */
pf = delayed_free.pf + (delayed_free.index ^ 1);
__free_zapped_classes(pf);
delayed_free.scheduled = false;
/*
* If there's anything on the open list, close and start a new callback.
*/
call_rcu_zapped(delayed_free.pf + delayed_free.index);
current->lockdep_recursion = 0;
arch_spin_unlock(&lockdep_lock);
raw_local_irq_restore(flags);
}
/*
* Remove all lock classes from the class hash table and from the
* all_lock_classes list whose key or name is in the address range [start,
* start + size). Move these lock classes to the zapped_classes list. Must
* be called with the graph lock held.
*/
static void __lockdep_free_key_range(struct pending_free *pf, void *start,
unsigned long size)
{
struct lock_class *class;
struct hlist_head *head;
int i;
/* Unhash all classes that were created by a module. */
for (i = 0; i < CLASSHASH_SIZE; i++) {
head = classhash_table + i;
hlist_for_each_entry_rcu(class, head, hash_entry) {
if (!within(class->key, start, size) &&
!within(class->name, start, size))
continue;
zap_class(pf, class);
}
}
}
/*
* Used in module.c to remove lock classes from memory that is going to be
* freed; and possibly re-used by other modules.
*
* We will have had one synchronize_rcu() before getting here, so we're
* guaranteed nobody will look up these exact classes -- they're properly dead
* but still allocated.
*/
static void lockdep_free_key_range_reg(void *start, unsigned long size)
{
struct pending_free *pf;
unsigned long flags;
init_data_structures_once();
raw_local_irq_save(flags);
arch_spin_lock(&lockdep_lock);
current->lockdep_recursion = 1;
pf = get_pending_free();
__lockdep_free_key_range(pf, start, size);
call_rcu_zapped(pf);
current->lockdep_recursion = 0;
arch_spin_unlock(&lockdep_lock);
raw_local_irq_restore(flags);
/*
* Wait for any possible iterators from look_up_lock_class() to pass
* before continuing to free the memory they refer to.
*/
synchronize_rcu();
}
/*
* Free all lockdep keys in the range [start, start+size). Does not sleep.
* Ignores debug_locks. Must only be used by the lockdep selftests.
*/
static void lockdep_free_key_range_imm(void *start, unsigned long size)
{
struct pending_free *pf = delayed_free.pf;
unsigned long flags;
init_data_structures_once();
raw_local_irq_save(flags);
arch_spin_lock(&lockdep_lock);
__lockdep_free_key_range(pf, start, size);
__free_zapped_classes(pf);
arch_spin_unlock(&lockdep_lock);
raw_local_irq_restore(flags);
}
void lockdep_free_key_range(void *start, unsigned long size)
{
init_data_structures_once();
if (inside_selftest())
lockdep_free_key_range_imm(start, size);
else
lockdep_free_key_range_reg(start, size);
}
/*
* Check whether any element of the @lock->class_cache[] array refers to a
* registered lock class. The caller must hold either the graph lock or the
* RCU read lock.
*/
static bool lock_class_cache_is_registered(struct lockdep_map *lock)
{
struct lock_class *class;
struct hlist_head *head;
int i, j;
for (i = 0; i < CLASSHASH_SIZE; i++) {
head = classhash_table + i;
hlist_for_each_entry_rcu(class, head, hash_entry) {
for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
if (lock->class_cache[j] == class)
return true;
}
}
return false;
}
/* The caller must hold the graph lock. Does not sleep. */
static void __lockdep_reset_lock(struct pending_free *pf,
struct lockdep_map *lock)
{
struct lock_class *class;
int j;
/*
* Remove all classes this lock might have:
*/
for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
/*
* If the class exists we look it up and zap it:
*/
class = look_up_lock_class(lock, j);
if (class)
zap_class(pf, class);
}
/*
* Debug check: in the end all mapped classes should
* be gone.
*/
if (WARN_ON_ONCE(lock_class_cache_is_registered(lock)))
debug_locks_off();
}
/*
* Remove all information lockdep has about a lock if debug_locks == 1. Free
* released data structures from RCU context.
*/
static void lockdep_reset_lock_reg(struct lockdep_map *lock)
{
struct pending_free *pf;
unsigned long flags;
int locked;
raw_local_irq_save(flags);
locked = graph_lock();
if (!locked)
goto out_irq;
pf = get_pending_free();
__lockdep_reset_lock(pf, lock);
call_rcu_zapped(pf);
graph_unlock();
out_irq:
raw_local_irq_restore(flags);
}
/*
* Reset a lock. Does not sleep. Ignores debug_locks. Must only be used by the
* lockdep selftests.
*/
static void lockdep_reset_lock_imm(struct lockdep_map *lock)
{
struct pending_free *pf = delayed_free.pf;
unsigned long flags;
raw_local_irq_save(flags);
arch_spin_lock(&lockdep_lock);
__lockdep_reset_lock(pf, lock);
__free_zapped_classes(pf);
arch_spin_unlock(&lockdep_lock);
raw_local_irq_restore(flags);
}
void lockdep_reset_lock(struct lockdep_map *lock)
{
init_data_structures_once();
if (inside_selftest())
lockdep_reset_lock_imm(lock);
else
lockdep_reset_lock_reg(lock);
}
/* Unregister a dynamically allocated key. */
void lockdep_unregister_key(struct lock_class_key *key)
{
struct hlist_head *hash_head = keyhashentry(key);
struct lock_class_key *k;
struct pending_free *pf;
unsigned long flags;
bool found = false;
might_sleep();
if (WARN_ON_ONCE(static_obj(key)))
return;
raw_local_irq_save(flags);
if (!graph_lock())
goto out_irq;
pf = get_pending_free();
hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
if (k == key) {
hlist_del_rcu(&k->hash_entry);
found = true;
break;
}
}
WARN_ON_ONCE(!found);
__lockdep_free_key_range(pf, key, 1);
call_rcu_zapped(pf);
graph_unlock();
out_irq:
raw_local_irq_restore(flags);
/* Wait until is_dynamic_key() has finished accessing k->hash_entry. */
synchronize_rcu();
}
EXPORT_SYMBOL_GPL(lockdep_unregister_key);
void __init lockdep_init(void)
{
printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
printk(" memory used by lock dependency info: %zu kB\n",
(sizeof(lock_classes) +
sizeof(classhash_table) +
sizeof(list_entries) +
sizeof(list_entries_in_use) +
sizeof(chainhash_table) +
sizeof(delayed_free)
#ifdef CONFIG_PROVE_LOCKING
+ sizeof(lock_cq)
+ sizeof(lock_chains)
+ sizeof(lock_chains_in_use)
+ sizeof(chain_hlocks)
#endif
) / 1024
);
printk(" per task-struct memory footprint: %zu bytes\n",
sizeof(((struct task_struct *)NULL)->held_locks));
}
static void
print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
const void *mem_to, struct held_lock *hlock)
{
if (!debug_locks_off())
return;
if (debug_locks_silent)
return;
pr_warn("\n");
pr_warn("=========================\n");
pr_warn("WARNING: held lock freed!\n");
print_kernel_ident();
pr_warn("-------------------------\n");
pr_warn("%s/%d is freeing memory %px-%px, with a lock still held there!\n",
curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
print_lock(hlock);
lockdep_print_held_locks(curr);
pr_warn("\nstack backtrace:\n");
dump_stack();
}
static inline int not_in_range(const void* mem_from, unsigned long mem_len,
const void* lock_from, unsigned long lock_len)
{
return lock_from + lock_len <= mem_from ||
mem_from + mem_len <= lock_from;
}
/*
* Called when kernel memory is freed (or unmapped), or if a lock
* is destroyed or reinitialized - this code checks whether there is
* any held lock in the memory range of <from> to <to>:
*/
void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
{
struct task_struct *curr = current;
struct held_lock *hlock;
unsigned long flags;
int i;
if (unlikely(!debug_locks))
return;
raw_local_irq_save(flags);
for (i = 0; i < curr->lockdep_depth; i++) {
hlock = curr->held_locks + i;
if (not_in_range(mem_from, mem_len, hlock->instance,
sizeof(*hlock->instance)))
continue;
print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
break;
}
raw_local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
static void print_held_locks_bug(void)
{
if (!debug_locks_off())
return;
if (debug_locks_silent)
return;
pr_warn("\n");
pr_warn("====================================\n");
pr_warn("WARNING: %s/%d still has locks held!\n",
current->comm, task_pid_nr(current));
print_kernel_ident();
pr_warn("------------------------------------\n");
lockdep_print_held_locks(current);
pr_warn("\nstack backtrace:\n");
dump_stack();
}
void debug_check_no_locks_held(void)
{
if (unlikely(current->lockdep_depth > 0))
print_held_locks_bug();
}
EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
#ifdef __KERNEL__
void debug_show_all_locks(void)
{
struct task_struct *g, *p;
if (unlikely(!debug_locks)) {
pr_warn("INFO: lockdep is turned off.\n");
return;
}
pr_warn("\nShowing all locks held in the system:\n");
rcu_read_lock();
for_each_process_thread(g, p) {
if (!p->lockdep_depth)
continue;
lockdep_print_held_locks(p);
touch_nmi_watchdog();
touch_all_softlockup_watchdogs();
}
rcu_read_unlock();
pr_warn("\n");
pr_warn("=============================================\n\n");
}
EXPORT_SYMBOL_GPL(debug_show_all_locks);
#endif
/*
* Careful: only use this function if you are sure that
* the task cannot run in parallel!
*/
void debug_show_held_locks(struct task_struct *task)
{
if (unlikely(!debug_locks)) {
printk("INFO: lockdep is turned off.\n");
return;
}
lockdep_print_held_locks(task);
}
EXPORT_SYMBOL_GPL(debug_show_held_locks);
asmlinkage __visible void lockdep_sys_exit(void)
{
struct task_struct *curr = current;
if (unlikely(curr->lockdep_depth)) {
if (!debug_locks_off())
return;
pr_warn("\n");
pr_warn("================================================\n");
pr_warn("WARNING: lock held when returning to user space!\n");
print_kernel_ident();
pr_warn("------------------------------------------------\n");
pr_warn("%s/%d is leaving the kernel with locks still held!\n",
curr->comm, curr->pid);
lockdep_print_held_locks(curr);
}
/*
* The lock history for each syscall should be independent. So wipe the
* slate clean on return to userspace.
*/
lockdep_invariant_state(false);
}
void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
{
struct task_struct *curr = current;
/* Note: the following can be executed concurrently, so be careful. */
pr_warn("\n");
pr_warn("=============================\n");
pr_warn("WARNING: suspicious RCU usage\n");
print_kernel_ident();
pr_warn("-----------------------------\n");
pr_warn("%s:%d %s!\n", file, line, s);
pr_warn("\nother info that might help us debug this:\n\n");
pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
!rcu_lockdep_current_cpu_online()
? "RCU used illegally from offline CPU!\n"
: !rcu_is_watching()
? "RCU used illegally from idle CPU!\n"
: "",
rcu_scheduler_active, debug_locks);
/*
* If a CPU is in the RCU-free window in idle (ie: in the section
* between rcu_idle_enter() and rcu_idle_exit(), then RCU
* considers that CPU to be in an "extended quiescent state",
* which means that RCU will be completely ignoring that CPU.
* Therefore, rcu_read_lock() and friends have absolutely no
* effect on a CPU running in that state. In other words, even if
* such an RCU-idle CPU has called rcu_read_lock(), RCU might well
* delete data structures out from under it. RCU really has no
* choice here: we need to keep an RCU-free window in idle where
* the CPU may possibly enter into low power mode. This way we can
* notice an extended quiescent state to other CPUs that started a grace
* period. Otherwise we would delay any grace period as long as we run
* in the idle task.
*
* So complain bitterly if someone does call rcu_read_lock(),
* rcu_read_lock_bh() and so on from extended quiescent states.
*/
if (!rcu_is_watching())
pr_warn("RCU used illegally from extended quiescent state!\n");
lockdep_print_held_locks(curr);
pr_warn("\nstack backtrace:\n");
dump_stack();
}
EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);
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