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Merge branches 'doc.2017.01.15b', 'dyntick.2017.01.23a', 'fixes.2017.01.23a', 'srcu.2017.01.25a' and 'torture.2017.01.15b' into HEAD 

doc.2017.01.15b: Documentation updates
dyntick.2017.01.23a: Dyntick tracking consolidation
fixes.2017.01.23a: Miscellaneous fixes
srcu.2017.01.25a: SRCU rewrite, fixes, and verification
torture.2017.01.15b: Torture-test updates
This commit is contained in:
Paul E. McKenney 2017-01-25 12:56:05 -08:00
parent e3c50dfbbd 38d30b336c 8dc79888a7 7f554a3d05 7d025948e4
commit 31945aa9f1
72 changed files with 2003 additions and 256 deletions
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5
Documentation/RCU/trace.txt
View File

@ -237,7 +237,7 @@ o "ktl" is the low-order 16 bits (in hexadecimal) of the count of
The output of "cat rcu/rcu_preempt/rcuexp" looks as follows:
s=21872 wd1=0 wd2=0 wd3=5 n=0 enq=0 sc=21872
s=21872 wd1=0 wd2=0 wd3=5 enq=0 sc=21872
These fields are as follows:
@ -249,9 +249,6 @@ o "wd1", "wd2", and "wd3" are the number of times that an attempt
completed an expedited grace period that satisfies the attempted
request. "Our work is done."
o "n" is number of times that a concurrent CPU-hotplug operation
forced a fallback to a normal grace period.
o "enq" is the number of quiescent states still outstanding.
o "sc" is the number of times that the attempt to start a

33
include/linux/llist.h
View File

@ -3,28 +3,33 @@
/*
* Lock-less NULL terminated single linked list
*
* If there are multiple producers and multiple consumers, llist_add
* can be used in producers and llist_del_all can be used in
* consumers. They can work simultaneously without lock. But
* llist_del_first can not be used here. Because llist_del_first
* depends on list->first->next does not changed if list->first is not
* changed during its operation, but llist_del_first, llist_add,
* llist_add (or llist_del_all, llist_add, llist_add) sequence in
* another consumer may violate that.
* Cases where locking is not needed:
* If there are multiple producers and multiple consumers, llist_add can be
* used in producers and llist_del_all can be used in consumers simultaneously
* without locking. Also a single consumer can use llist_del_first while
* multiple producers simultaneously use llist_add, without any locking.
*
* If there are multiple producers and one consumer, llist_add can be
* used in producers and llist_del_all or llist_del_first can be used
* in the consumer.
* Cases where locking is needed:
* If we have multiple consumers with llist_del_first used in one consumer, and
* llist_del_first or llist_del_all used in other consumers, then a lock is
* needed. This is because llist_del_first depends on list->first->next not
* changing, but without lock protection, there's no way to be sure about that
* if a preemption happens in the middle of the delete operation and on being
* preempted back, the list->first is the same as before causing the cmpxchg in
* llist_del_first to succeed. For example, while a llist_del_first operation
* is in progress in one consumer, then a llist_del_first, llist_add,
* llist_add (or llist_del_all, llist_add, llist_add) sequence in another
* consumer may cause violations.
*
* This can be summarized as follow:
* This can be summarized as follows:
*
* | add | del_first | del_all
* add | - | - | -
* del_first | | L | L
* del_all | | | -
*
* Where "-" stands for no lock is needed, while "L" stands for lock
* is needed.
* Where, a particular row's operation can happen concurrently with a column's
* operation, with "-" being no lock needed, while "L" being lock is needed.
*
* The list entries deleted via llist_del_all can be traversed with
* traversing function such as llist_for_each etc. But the list

12
include/linux/rcupdate.h
View File

@ -1161,5 +1161,17 @@ do { \
ftrace_dump(oops_dump_mode); \
} while (0)
/*
* Place this after a lock-acquisition primitive to guarantee that
* an UNLOCK+LOCK pair acts as a full barrier. This guarantee applies
* if the UNLOCK and LOCK are executed by the same CPU or if the
* UNLOCK and LOCK operate on the same lock variable.
*/
#ifdef CONFIG_PPC
#define smp_mb__after_unlock_lock() smp_mb() /* Full ordering for lock. */
#else /* #ifdef CONFIG_PPC */
#define smp_mb__after_unlock_lock() do { } while (0)
#endif /* #else #ifdef CONFIG_PPC */
#endif /* __LINUX_RCUPDATE_H */

6
include/linux/rcutiny.h
View File

@ -27,6 +27,12 @@
#include <linux/cache.h>
struct rcu_dynticks;
static inline int rcu_dynticks_snap(struct rcu_dynticks *rdtp)
{
return 0;
}
static inline unsigned long get_state_synchronize_rcu(void)
{
return 0;

10
include/linux/srcu.h
View File

@ -33,9 +33,9 @@
#include <linux/rcupdate.h>
#include <linux/workqueue.h>
struct srcu_struct_array {
unsigned long c[2];
unsigned long seq[2];
struct srcu_array {
unsigned long lock_count[2];
unsigned long unlock_count[2];
};
struct rcu_batch {
@ -46,7 +46,7 @@ struct rcu_batch {
struct srcu_struct {
unsigned long completed;
struct srcu_struct_array __percpu *per_cpu_ref;
struct srcu_array __percpu *per_cpu_ref;
spinlock_t queue_lock; /* protect ->batch_queue, ->running */
bool running;
/* callbacks just queued */
@ -118,7 +118,7 @@ void process_srcu(struct work_struct *work);
* See include/linux/percpu-defs.h for the rules on per-CPU variables.
*/
#define __DEFINE_SRCU(name, is_static) \
static DEFINE_PER_CPU(struct srcu_struct_array, name##_srcu_array);\
static DEFINE_PER_CPU(struct srcu_array, name##_srcu_array);\
is_static struct srcu_struct name = __SRCU_STRUCT_INIT(name)
#define DEFINE_SRCU(name) __DEFINE_SRCU(name, /* not static */)
#define DEFINE_STATIC_SRCU(name) __DEFINE_SRCU(name, static)

10
include/trace/events/rcu.h
View File

@ -385,11 +385,11 @@ TRACE_EVENT(rcu_quiescent_state_report,
/*
* Tracepoint for quiescent states detected by force_quiescent_state().
* These trace events include the type of RCU, the grace-period number
* that was blocked by the CPU, the CPU itself, and the type of quiescent
* state, which can be "dti" for dyntick-idle mode, "ofl" for CPU offline,
* or "kick" when kicking a CPU that has been in dyntick-idle mode for
* too long.
* These trace events include the type of RCU, the grace-period number that
* was blocked by the CPU, the CPU itself, and the type of quiescent state,
* which can be "dti" for dyntick-idle mode, "ofl" for CPU offline, "kick"
* when kicking a CPU that has been in dyntick-idle mode for too long, or
* "rqc" if the CPU got a quiescent state via its rcu_qs_ctr.
*/
TRACE_EVENT(rcu_fqs,

14
init/Kconfig
View File

@ -529,7 +529,6 @@ config SRCU
config TASKS_RCU
bool
default n
depends on !UML
select SRCU
help
This option enables a task-based RCU implementation that uses
@ -781,19 +780,6 @@ config RCU_NOCB_CPU_ALL
endchoice
config RCU_EXPEDITE_BOOT
bool
default n
help
This option enables expedited grace periods at boot time,
as if rcu_expedite_gp() had been invoked early in boot.
The corresponding rcu_unexpedite_gp() is invoked from
rcu_end_inkernel_boot(), which is intended to be invoked
at the end of the kernel-only boot sequence, just before
init is exec'ed.
Accept the default if unsure.
endmenu # "RCU Subsystem"
config BUILD_BIN2C

12
kernel/locking/lockdep.c
View File

@ -4412,13 +4412,13 @@ void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
#endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
/* Note: the following can be executed concurrently, so be careful. */
printk("\n");
printk("===============================\n");
printk("[ INFO: suspicious RCU usage. ]\n");
pr_err("===============================\n");
pr_err("[ ERR: suspicious RCU usage. ]\n");
print_kernel_ident();
printk("-------------------------------\n");
printk("%s:%d %s!\n", file, line, s);
printk("\nother info that might help us debug this:\n\n");
printk("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
pr_err("-------------------------------\n");
pr_err("%s:%d %s!\n", file, line, s);
pr_err("\nother info that might help us debug this:\n\n");
pr_err("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
!rcu_lockdep_current_cpu_online()
? "RCU used illegally from offline CPU!\n"
: !rcu_is_watching()

6
kernel/locking/locktorture.c
View File

@ -780,6 +780,10 @@ static void lock_torture_cleanup(void)
else
lock_torture_print_module_parms(cxt.cur_ops,
"End of test: SUCCESS");
kfree(cxt.lwsa);
kfree(cxt.lrsa);
end:
torture_cleanup_end();
}
@ -924,6 +928,8 @@ static int __init lock_torture_init(void)
GFP_KERNEL);
if (reader_tasks == NULL) {
VERBOSE_TOROUT_ERRSTRING("reader_tasks: Out of memory");
kfree(writer_tasks);
writer_tasks = NULL;
firsterr = -ENOMEM;
goto unwind;
}

4
kernel/membarrier.c
View File

@ -16,6 +16,7 @@
#include <linux/syscalls.h>
#include <linux/membarrier.h>
#include <linux/tick.h>
/*
* Bitmask made from a "or" of all commands within enum membarrier_cmd,
@ -51,6 +52,9 @@
*/
SYSCALL_DEFINE2(membarrier, int, cmd, int, flags)
{
/* MEMBARRIER_CMD_SHARED is not compatible with nohz_full. */
if (tick_nohz_full_enabled())
return -ENOSYS;
if (unlikely(flags))
return -EINVAL;
switch (cmd) {

19
kernel/rcu/rcutorture.c
View File

@ -564,10 +564,25 @@ static void srcu_torture_stats(void)
pr_alert("%s%s per-CPU(idx=%d):",
torture_type, TORTURE_FLAG, idx);
for_each_possible_cpu(cpu) {
unsigned long l0, l1;
unsigned long u0, u1;
long c0, c1;
struct srcu_array *counts = per_cpu_ptr(srcu_ctlp->per_cpu_ref, cpu);
c0 = (long)per_cpu_ptr(srcu_ctlp->per_cpu_ref, cpu)->c[!idx];
c1 = (long)per_cpu_ptr(srcu_ctlp->per_cpu_ref, cpu)->c[idx];
u0 = counts->unlock_count[!idx];
u1 = counts->unlock_count[idx];
/*
* Make sure that a lock is always counted if the corresponding
* unlock is counted.
*/
smp_rmb();
l0 = counts->lock_count[!idx];
l1 = counts->lock_count[idx];
c0 = l0 - u0;
c1 = l1 - u1;
pr_cont(" %d(%ld,%ld)", cpu, c0, c1);
}
pr_cont("\n");

143
kernel/rcu/srcu.c
View File

@ -106,7 +106,7 @@ static int init_srcu_struct_fields(struct srcu_struct *sp)
rcu_batch_init(&sp->batch_check1);
rcu_batch_init(&sp->batch_done);
INIT_DELAYED_WORK(&sp->work, process_srcu);
sp->per_cpu_ref = alloc_percpu(struct srcu_struct_array);
sp->per_cpu_ref = alloc_percpu(struct srcu_array);
return sp->per_cpu_ref ? 0 : -ENOMEM;
}
@ -141,114 +141,77 @@ EXPORT_SYMBOL_GPL(init_srcu_struct);
#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
/*
* Returns approximate total of the readers' ->seq[] values for the
* Returns approximate total of the readers' ->lock_count[] values for the
* rank of per-CPU counters specified by idx.
*/
static unsigned long srcu_readers_seq_idx(struct srcu_struct *sp, int idx)
static unsigned long srcu_readers_lock_idx(struct srcu_struct *sp, int idx)
{
int cpu;
unsigned long sum = 0;
unsigned long t;
for_each_possible_cpu(cpu) {
t = READ_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->seq[idx]);
sum += t;
struct srcu_array *cpuc = per_cpu_ptr(sp->per_cpu_ref, cpu);
sum += READ_ONCE(cpuc->lock_count[idx]);
}
return sum;
}
/*
* Returns approximate number of readers active on the specified rank
* of the per-CPU ->c[] counters.
* Returns approximate total of the readers' ->unlock_count[] values for the
* rank of per-CPU counters specified by idx.
*/
static unsigned long srcu_readers_active_idx(struct srcu_struct *sp, int idx)
static unsigned long srcu_readers_unlock_idx(struct srcu_struct *sp, int idx)
{
int cpu;
unsigned long sum = 0;
unsigned long t;
for_each_possible_cpu(cpu) {
t = READ_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->c[idx]);
sum += t;
struct srcu_array *cpuc = per_cpu_ptr(sp->per_cpu_ref, cpu);
sum += READ_ONCE(cpuc->unlock_count[idx]);
}
return sum;
}
/*
* Return true if the number of pre-existing readers is determined to
* be stably zero. An example unstable zero can occur if the call
* to srcu_readers_active_idx() misses an __srcu_read_lock() increment,
* but due to task migration, sees the corresponding __srcu_read_unlock()
* decrement. This can happen because srcu_readers_active_idx() takes
* time to sum the array, and might in fact be interrupted or preempted
* partway through the summation.
* be zero.
*/
static bool srcu_readers_active_idx_check(struct srcu_struct *sp, int idx)
{
unsigned long seq;
unsigned long unlocks;
seq = srcu_readers_seq_idx(sp, idx);
unlocks = srcu_readers_unlock_idx(sp, idx);
/*
* The following smp_mb() A pairs with the smp_mb() B located in
* __srcu_read_lock(). This pairing ensures that if an
* __srcu_read_lock() increments its counter after the summation
* in srcu_readers_active_idx(), then the corresponding SRCU read-side
* critical section will see any changes made prior to the start
* of the current SRCU grace period.
* Make sure that a lock is always counted if the corresponding unlock
* is counted. Needs to be a smp_mb() as the read side may contain a
* read from a variable that is written to before the synchronize_srcu()
* in the write side. In this case smp_mb()s A and B act like the store
* buffering pattern.
*
* Also, if the above call to srcu_readers_seq_idx() saw the
* increment of ->seq[], then the call to srcu_readers_active_idx()
* must see the increment of ->c[].
* This smp_mb() also pairs with smp_mb() C to prevent accesses after the
* synchronize_srcu() from being executed before the grace period ends.
*/
smp_mb(); /* A */
/*
* Note that srcu_readers_active_idx() can incorrectly return
* zero even though there is a pre-existing reader throughout.
* To see this, suppose that task A is in a very long SRCU
* read-side critical section that started on CPU 0, and that
* no other reader exists, so that the sum of the counters
* is equal to one. Then suppose that task B starts executing
* srcu_readers_active_idx(), summing up to CPU 1, and then that
* task C starts reading on CPU 0, so that its increment is not
* summed, but finishes reading on CPU 2, so that its decrement
* -is- summed. Then when task B completes its sum, it will
* incorrectly get zero, despite the fact that task A has been
* in its SRCU read-side critical section the whole time.
* If the locks are the same as the unlocks, then there must have
* been no readers on this index at some time in between. This does not
* mean that there are no more readers, as one could have read the
* current index but not have incremented the lock counter yet.
*
* We therefore do a validation step should srcu_readers_active_idx()
* return zero.
* Possible bug: There is no guarantee that there haven't been ULONG_MAX
* increments of ->lock_count[] since the unlocks were counted, meaning
* that this could return true even if there are still active readers.
* Since there are no memory barriers around srcu_flip(), the CPU is not
* required to increment ->completed before running
* srcu_readers_unlock_idx(), which means that there could be an
* arbitrarily large number of critical sections that execute after
* srcu_readers_unlock_idx() but use the old value of ->completed.
*/
if (srcu_readers_active_idx(sp, idx) != 0)
return false;
/*
* The remainder of this function is the validation step.
* The following smp_mb() D pairs with the smp_mb() C in
* __srcu_read_unlock(). If the __srcu_read_unlock() was seen
* by srcu_readers_active_idx() above, then any destructive
* operation performed after the grace period will happen after
* the corresponding SRCU read-side critical section.
*
* Note that there can be at most NR_CPUS worth of readers using
* the old index, which is not enough to overflow even a 32-bit
* integer. (Yes, this does mean that systems having more than
* a billion or so CPUs need to be 64-bit systems.) Therefore,
* the sum of the ->seq[] counters cannot possibly overflow.
* Therefore, the only way that the return values of the two
* calls to srcu_readers_seq_idx() can be equal is if there were
* no increments of the corresponding rank of ->seq[] counts
* in the interim. But the missed-increment scenario laid out
* above includes an increment of the ->seq[] counter by
* the corresponding __srcu_read_lock(). Therefore, if this
* scenario occurs, the return values from the two calls to
* srcu_readers_seq_idx() will differ, and thus the validation
* step below suffices.
*/
smp_mb(); /* D */
return srcu_readers_seq_idx(sp, idx) == seq;
return srcu_readers_lock_idx(sp, idx) == unlocks;
}
/**
@ -266,8 +229,12 @@ static bool srcu_readers_active(struct srcu_struct *sp)
unsigned long sum = 0;
for_each_possible_cpu(cpu) {
sum += READ_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->c[0]);
sum += READ_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->c[1]);
struct srcu_array *cpuc = per_cpu_ptr(sp->per_cpu_ref, cpu);
sum += READ_ONCE(cpuc->lock_count[0]);
sum += READ_ONCE(cpuc->lock_count[1]);
sum -= READ_ONCE(cpuc->unlock_count[0]);
sum -= READ_ONCE(cpuc->unlock_count[1]);
}
return sum;
}
@ -298,9 +265,8 @@ int __srcu_read_lock(struct srcu_struct *sp)
int idx;
idx = READ_ONCE(sp->completed) & 0x1;
__this_cpu_inc(sp->per_cpu_ref->c[idx]);
__this_cpu_inc(sp->per_cpu_ref->lock_count[idx]);
smp_mb(); /* B */ /* Avoid leaking the critical section. */
__this_cpu_inc(sp->per_cpu_ref->seq[idx]);
return idx;
}
EXPORT_SYMBOL_GPL(__srcu_read_lock);
@ -314,7 +280,7 @@ EXPORT_SYMBOL_GPL(__srcu_read_lock);
void __srcu_read_unlock(struct srcu_struct *sp, int idx)
{
smp_mb(); /* C */ /* Avoid leaking the critical section. */
this_cpu_dec(sp->per_cpu_ref->c[idx]);
this_cpu_inc(sp->per_cpu_ref->unlock_count[idx]);
}
EXPORT_SYMBOL_GPL(__srcu_read_unlock);
@ -349,12 +315,21 @@ static bool try_check_zero(struct srcu_struct *sp, int idx, int trycount)
/*
* Increment the ->completed counter so that future SRCU readers will
* use the other rank of the ->c[] and ->seq[] arrays. This allows
* use the other rank of the ->(un)lock_count[] arrays. This allows
* us to wait for pre-existing readers in a starvation-free manner.
*/
static void srcu_flip(struct srcu_struct *sp)
{
sp->completed++;
WRITE_ONCE(sp->completed, sp->completed + 1);
/*
* Ensure that if the updater misses an __srcu_read_unlock()
* increment, that task's next __srcu_read_lock() will see the
* above counter update. Note that both this memory barrier
* and the one in srcu_readers_active_idx_check() provide the
* guarantee for __srcu_read_lock().
*/
smp_mb(); /* D */ /* Pairs with C. */
}
/*
@ -392,6 +367,7 @@ void call_srcu(struct srcu_struct *sp, struct rcu_head *head,
head->next = NULL;
head->func = func;
spin_lock_irqsave(&sp->queue_lock, flags);
smp_mb__after_unlock_lock(); /* Caller's prior accesses before GP. */
rcu_batch_queue(&sp->batch_queue, head);
if (!sp->running) {
sp->running = true;
@ -425,6 +401,7 @@ static void __synchronize_srcu(struct srcu_struct *sp, int trycount)
head->next = NULL;
head->func = wakeme_after_rcu;
spin_lock_irq(&sp->queue_lock);
smp_mb__after_unlock_lock(); /* Caller's prior accesses before GP. */
if (!sp->running) {
/* steal the processing owner */
sp->running = true;
@ -444,8 +421,11 @@ static void __synchronize_srcu(struct srcu_struct *sp, int trycount)
spin_unlock_irq(&sp->queue_lock);
}
if (!done)
if (!done) {
wait_for_completion(&rcu.completion);
smp_mb(); /* Caller's later accesses after GP. */
}
}
/**
@ -613,7 +593,8 @@ static void srcu_advance_batches(struct srcu_struct *sp, int trycount)
/*
* Invoke a limited number of SRCU callbacks that have passed through
* their grace period. If there are more to do, SRCU will reschedule
* the workqueue.
* the workqueue. Note that needed memory barriers have been executed
* in this task's context by srcu_readers_active_idx_check().
*/
static void srcu_invoke_callbacks(struct srcu_struct *sp)
{

2
kernel/rcu/tiny.c
View File

@ -41,8 +41,6 @@
/* Forward declarations for tiny_plugin.h. */
struct rcu_ctrlblk;
static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp);
static void rcu_process_callbacks(struct softirq_action *unused);
static void __call_rcu(struct rcu_head *head,
rcu_callback_t func,
struct rcu_ctrlblk *rcp);

258
kernel/rcu/tree.c
View File

@ -281,6 +281,116 @@ static DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = {
#endif /* #ifdef CONFIG_NO_HZ_FULL_SYSIDLE */
};
/*
* Record entry into an extended quiescent state. This is only to be
* called when not already in an extended quiescent state.
*/
static void rcu_dynticks_eqs_enter(void)
{
struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
int special;
/*
* CPUs seeing atomic_inc_return() must see prior RCU read-side
* critical sections, and we also must force ordering with the
* next idle sojourn.
*/
special = atomic_inc_return(&rdtp->dynticks);
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && special & 0x1);
}
/*
* Record exit from an extended quiescent state. This is only to be
* called from an extended quiescent state.
*/
static void rcu_dynticks_eqs_exit(void)
{
struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
int special;
/*
* CPUs seeing atomic_inc_return() must see prior idle sojourns,
* and we also must force ordering with the next RCU read-side
* critical section.
*/
special = atomic_inc_return(&rdtp->dynticks);
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !(special & 0x1));
}
/*
* Reset the current CPU's ->dynticks counter to indicate that the
* newly onlined CPU is no longer in an extended quiescent state.
* This will either leave the counter unchanged, or increment it
* to the next non-quiescent value.
*
* The non-atomic test/increment sequence works because the upper bits
* of the ->dynticks counter are manipulated only by the corresponding CPU,
* or when the corresponding CPU is offline.
*/
static void rcu_dynticks_eqs_online(void)
{
struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
if (atomic_read(&rdtp->dynticks) & 0x1)
return;
atomic_add(0x1, &rdtp->dynticks);
}
/*
* Is the current CPU in an extended quiescent state?
*
* No ordering, as we are sampling CPU-local information.
*/
bool rcu_dynticks_curr_cpu_in_eqs(void)
{
struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
return !(atomic_read(&rdtp->dynticks) & 0x1);
}
/*
* Snapshot the ->dynticks counter with full ordering so as to allow
* stable comparison of this counter with past and future snapshots.
*/
int rcu_dynticks_snap(struct rcu_dynticks *rdtp)
{
int snap = atomic_add_return(0, &rdtp->dynticks);
return snap;
}
/*
* Return true if the snapshot returned from rcu_dynticks_snap()
* indicates that RCU is in an extended quiescent state.
*/
static bool rcu_dynticks_in_eqs(int snap)
{
return !(snap & 0x1);
}
/*
* Return true if the CPU corresponding to the specified rcu_dynticks
* structure has spent some time in an extended quiescent state since
* rcu_dynticks_snap() returned the specified snapshot.
*/
static bool rcu_dynticks_in_eqs_since(struct rcu_dynticks *rdtp, int snap)
{
return snap != rcu_dynticks_snap(rdtp);
}
/*
* Do a double-increment of the ->dynticks counter to emulate a
* momentary idle-CPU quiescent state.
*/
static void rcu_dynticks_momentary_idle(void)
{
struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
int special = atomic_add_return(2, &rdtp->dynticks);
/* It is illegal to call this from idle state. */
WARN_ON_ONCE(!(special & 0x1));
}
DEFINE_PER_CPU_SHARED_ALIGNED(unsigned long, rcu_qs_ctr);
EXPORT_PER_CPU_SYMBOL_GPL(rcu_qs_ctr);
@ -300,7 +410,6 @@ EXPORT_PER_CPU_SYMBOL_GPL(rcu_qs_ctr);
static void rcu_momentary_dyntick_idle(void)
{
struct rcu_data *rdp;
struct rcu_dynticks *rdtp;
int resched_mask;
struct rcu_state *rsp;
@ -327,10 +436,7 @@ static void rcu_momentary_dyntick_idle(void)
* quiescent state, with no need for this CPU to do anything
* further.
*/
rdtp = this_cpu_ptr(&rcu_dynticks);
smp_mb__before_atomic(); /* Earlier stuff before QS. */
atomic_add(2, &rdtp->dynticks); /* QS. */
smp_mb__after_atomic(); /* Later stuff after QS. */
rcu_dynticks_momentary_idle();
break;
}
}
@ -611,7 +717,7 @@ static int
cpu_has_callbacks_ready_to_invoke(struct rcu_data *rdp)
{
return &rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL] &&
rdp->nxttail[RCU_DONE_TAIL] != NULL;
rdp->nxttail[RCU_NEXT_TAIL] != NULL;
}
/*
@ -673,7 +779,7 @@ static void rcu_eqs_enter_common(long long oldval, bool user)
{
struct rcu_state *rsp;
struct rcu_data *rdp;
struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
RCU_TRACE(struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);)
trace_rcu_dyntick(TPS("Start"), oldval, rdtp->dynticks_nesting);
if (IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
@ -692,12 +798,7 @@ static void rcu_eqs_enter_common(long long oldval, bool user)
do_nocb_deferred_wakeup(rdp);
}
rcu_prepare_for_idle();
/* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */
smp_mb__before_atomic(); /* See above. */
atomic_inc(&rdtp->dynticks);
smp_mb__after_atomic(); /* Force ordering with next sojourn. */
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
atomic_read(&rdtp->dynticks) & 0x1);
rcu_dynticks_eqs_enter();
rcu_dynticks_task_enter();
/*
@ -826,15 +927,10 @@ void rcu_irq_exit_irqson(void)
*/
static void rcu_eqs_exit_common(long long oldval, int user)
{
struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
RCU_TRACE(struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);)
rcu_dynticks_task_exit();
smp_mb__before_atomic(); /* Force ordering w/previous sojourn. */
atomic_inc(&rdtp->dynticks);
/* CPUs seeing atomic_inc() must see later RCU read-side crit sects */
smp_mb__after_atomic(); /* See above. */
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
!(atomic_read(&rdtp->dynticks) & 0x1));
rcu_dynticks_eqs_exit();
rcu_cleanup_after_idle();
trace_rcu_dyntick(TPS("End"), oldval, rdtp->dynticks_nesting);
if (IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
@ -980,12 +1076,8 @@ void rcu_nmi_enter(void)
* to be in the outermost NMI handler that interrupted an RCU-idle
* period (observation due to Andy Lutomirski).
*/
if (!(atomic_read(&rdtp->dynticks) & 0x1)) {
smp_mb__before_atomic(); /* Force delay from prior write. */
atomic_inc(&rdtp->dynticks);
/* atomic_inc() before later RCU read-side crit sects */
smp_mb__after_atomic(); /* See above. */
WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1));
if (rcu_dynticks_curr_cpu_in_eqs()) {
rcu_dynticks_eqs_exit();
incby = 1;
}
rdtp->dynticks_nmi_nesting += incby;
@ -1010,7 +1102,7 @@ void rcu_nmi_exit(void)
* to us!)
*/
WARN_ON_ONCE(rdtp->dynticks_nmi_nesting <= 0);
WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1));
WARN_ON_ONCE(rcu_dynticks_curr_cpu_in_eqs());
/*
* If the nesting level is not 1, the CPU wasn't RCU-idle, so
@ -1023,11 +1115,7 @@ void rcu_nmi_exit(void)
/* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */
rdtp->dynticks_nmi_nesting = 0;
/* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */
smp_mb__before_atomic(); /* See above. */
atomic_inc(&rdtp->dynticks);
smp_mb__after_atomic(); /* Force delay to next write. */
WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1);
rcu_dynticks_eqs_enter();
}
/**
@ -1040,7 +1128,7 @@ void rcu_nmi_exit(void)
*/
bool notrace __rcu_is_watching(void)
{
return atomic_read(this_cpu_ptr(&rcu_dynticks.dynticks)) & 0x1;
return !rcu_dynticks_curr_cpu_in_eqs();
}
/**
@ -1123,9 +1211,9 @@ static int rcu_is_cpu_rrupt_from_idle(void)
static int dyntick_save_progress_counter(struct rcu_data *rdp,
bool *isidle, unsigned long *maxj)
{
rdp->dynticks_snap = atomic_add_return(0, &rdp->dynticks->dynticks);
rdp->dynticks_snap = rcu_dynticks_snap(rdp->dynticks);
rcu_sysidle_check_cpu(rdp, isidle, maxj);
if ((rdp->dynticks_snap & 0x1) == 0) {
if (rcu_dynticks_in_eqs(rdp->dynticks_snap)) {
trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("dti"));
if (ULONG_CMP_LT(READ_ONCE(rdp->gpnum) + ULONG_MAX / 4,
rdp->mynode->gpnum))
@ -1144,12 +1232,10 @@ static int dyntick_save_progress_counter(struct rcu_data *rdp,
static int rcu_implicit_dynticks_qs(struct rcu_data *rdp,
bool *isidle, unsigned long *maxj)
{
unsigned int curr;
unsigned long jtsq;
int *rcrmp;
unsigned int snap;
curr = (unsigned int)atomic_add_return(0, &rdp->dynticks->dynticks);
snap = (unsigned int)rdp->dynticks_snap;
unsigned long rjtsc;
struct rcu_node *rnp;
/*
* If the CPU passed through or entered a dynticks idle phase with
@ -1159,27 +1245,39 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp,
* read-side critical section that started before the beginning
* of the current RCU grace period.
*/
if ((curr & 0x1) == 0 || UINT_CMP_GE(curr, snap + 2)) {
if (rcu_dynticks_in_eqs_since(rdp->dynticks, rdp->dynticks_snap)) {
trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("dti"));
rdp->dynticks_fqs++;
return 1;
}
/* Compute and saturate jiffies_till_sched_qs. */
jtsq = jiffies_till_sched_qs;
rjtsc = rcu_jiffies_till_stall_check();
if (jtsq > rjtsc / 2) {
WRITE_ONCE(jiffies_till_sched_qs, rjtsc);
jtsq = rjtsc / 2;
} else if (jtsq < 1) {
WRITE_ONCE(jiffies_till_sched_qs, 1);
jtsq = 1;
}
/*
* Check for the CPU being offline, but only if the grace period
* is old enough. We don't need to worry about the CPU changing
* state: If we see it offline even once, it has been through a
* quiescent state.
*
* The reason for insisting that the grace period be at least
* one jiffy old is that CPUs that are not quite online and that
* have just gone offline can still execute RCU read-side critical
* sections.
* Has this CPU encountered a cond_resched_rcu_qs() since the
* beginning of the grace period? For this to be the case,
* the CPU has to have noticed the current grace period. This
* might not be the case for nohz_full CPUs looping in the kernel.
*/
if (ULONG_CMP_GE(rdp->rsp->gp_start + 2, jiffies))
return 0; /* Grace period is not old enough. */
barrier();
if (cpu_is_offline(rdp->cpu)) {
rnp = rdp->mynode;
if (time_after(jiffies, rdp->rsp->gp_start + jtsq) &&
READ_ONCE(rdp->rcu_qs_ctr_snap) != per_cpu(rcu_qs_ctr, rdp->cpu) &&
READ_ONCE(rdp->gpnum) == rnp->gpnum && !rdp->gpwrap) {
trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("rqc"));
return 1;
}
/* Check for the CPU being offline. */
if (!(rdp->grpmask & rcu_rnp_online_cpus(rnp))) {
trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("ofl"));
rdp->offline_fqs++;
return 1;
@ -1207,9 +1305,8 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp,
* warning delay.
*/
rcrmp = &per_cpu(rcu_sched_qs_mask, rdp->cpu);
if (ULONG_CMP_GE(jiffies,
rdp->rsp->gp_start + jiffies_till_sched_qs) ||
ULONG_CMP_GE(jiffies, rdp->rsp->jiffies_resched)) {
if (time_after(jiffies, rdp->rsp->gp_start + jtsq) ||
time_after(jiffies, rdp->rsp->jiffies_resched)) {
if (!(READ_ONCE(*rcrmp) & rdp->rsp->flavor_mask)) {
WRITE_ONCE(rdp->cond_resched_completed,
READ_ONCE(rdp->mynode->completed));
@ -1220,11 +1317,12 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp,
rdp->rsp->jiffies_resched += 5; /* Re-enable beating. */
}
/* And if it has been a really long time, kick the CPU as well. */
if (ULONG_CMP_GE(jiffies,
rdp->rsp->gp_start + 2 * jiffies_till_sched_qs) ||
ULONG_CMP_GE(jiffies, rdp->rsp->gp_start + jiffies_till_sched_qs))
resched_cpu(rdp->cpu); /* Force CPU into scheduler. */
/*
* If more than halfway to RCU CPU stall-warning time, do
* a resched_cpu() to try to loosen things up a bit.
*/
if (jiffies - rdp->rsp->gp_start > rcu_jiffies_till_stall_check() / 2)
resched_cpu(rdp->cpu);
return 0;
}
@ -1277,7 +1375,10 @@ static void rcu_check_gp_kthread_starvation(struct rcu_state *rsp)
}
/*
* Dump stacks of all tasks running on stalled CPUs.
* Dump stacks of all tasks running on stalled CPUs. First try using
* NMIs, but fall back to manual remote stack tracing on architectures
* that don't support NMI-based stack dumps. The NMI-triggered stack
* traces are more accurate because they are printed by the target CPU.
*/
static void rcu_dump_cpu_stacks(struct rcu_state *rsp)
{
@ -1287,11 +1388,10 @@ static void rcu_dump_cpu_stacks(struct rcu_state *rsp)
rcu_for_each_leaf_node(rsp, rnp) {
raw_spin_lock_irqsave_rcu_node(rnp, flags);
if (rnp->qsmask != 0) {
for_each_leaf_node_possible_cpu(rnp, cpu)
if (rnp->qsmask & leaf_node_cpu_bit(rnp, cpu))
if (!trigger_single_cpu_backtrace(cpu))
dump_cpu_task(cpu);
}
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
}
}
@ -1379,6 +1479,9 @@ static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gpnum)
(long)rsp->gpnum, (long)rsp->completed, totqlen);
if (ndetected) {
rcu_dump_cpu_stacks(rsp);
/* Complain about tasks blocking the grace period. */
rcu_print_detail_task_stall(rsp);
} else {
if (READ_ONCE(rsp->gpnum) != gpnum ||
READ_ONCE(rsp->completed) == gpnum) {
@ -1395,9 +1498,6 @@ static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gpnum)
}
}
/* Complain about tasks blocking the grace period. */
rcu_print_detail_task_stall(rsp);
rcu_check_gp_kthread_starvation(rsp);
panic_on_rcu_stall();
@ -2467,10 +2567,8 @@ rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp)
rnp = rdp->mynode;
raw_spin_lock_irqsave_rcu_node(rnp, flags);
if ((rdp->cpu_no_qs.b.norm &&
rdp->rcu_qs_ctr_snap == __this_cpu_read(rcu_qs_ctr)) ||
rdp->gpnum != rnp->gpnum || rnp->completed == rnp->gpnum ||
rdp->gpwrap) {
if (rdp->cpu_no_qs.b.norm || rdp->gpnum != rnp->gpnum ||
rnp->completed == rnp->gpnum || rdp->gpwrap) {
/*
* The grace period in which this quiescent state was
@ -2525,8 +2623,7 @@ rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp)
* Was there a quiescent state since the beginning of the grace
* period? If no, then exit and wait for the next call.
*/
if (rdp->cpu_no_qs.b.norm &&
rdp->rcu_qs_ctr_snap == __this_cpu_read(rcu_qs_ctr))
if (rdp->cpu_no_qs.b.norm)
return;
/*
@ -3480,9 +3577,7 @@ static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp)
rdp->core_needs_qs && rdp->cpu_no_qs.b.norm &&
rdp->rcu_qs_ctr_snap == __this_cpu_read(rcu_qs_ctr)) {
rdp->n_rp_core_needs_qs++;
} else if (rdp->core_needs_qs &&
(!rdp->cpu_no_qs.b.norm ||
rdp->rcu_qs_ctr_snap != __this_cpu_read(rcu_qs_ctr))) {
} else if (rdp->core_needs_qs && !rdp->cpu_no_qs.b.norm) {
rdp->n_rp_report_qs++;
return 1;
}
@ -3748,7 +3843,7 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
rdp->grpmask = leaf_node_cpu_bit(rdp->mynode, cpu);
rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != DYNTICK_TASK_EXIT_IDLE);
WARN_ON_ONCE(atomic_read(&rdp->dynticks->dynticks) != 1);
WARN_ON_ONCE(rcu_dynticks_in_eqs(rcu_dynticks_snap(rdp->dynticks)));
rdp->cpu = cpu;
rdp->rsp = rsp;
rcu_boot_init_nocb_percpu_data(rdp);
@ -3765,7 +3860,6 @@ static void
rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
{
unsigned long flags;
unsigned long mask;
struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
struct rcu_node *rnp = rcu_get_root(rsp);
@ -3778,8 +3872,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
init_callback_list(rdp); /* Re-enable callbacks on this CPU. */
rdp->dynticks->dynticks_nesting = DYNTICK_TASK_EXIT_IDLE;
rcu_sysidle_init_percpu_data(rdp->dynticks);
atomic_set(&rdp->dynticks->dynticks,
(atomic_read(&rdp->dynticks->dynticks) & ~0x1) + 1);
rcu_dynticks_eqs_online();
raw_spin_unlock_rcu_node(rnp); /* irqs remain disabled. */
/*
@ -3788,7 +3881,6 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
* of the next grace period.
*/
rnp = rdp->mynode;
mask = rdp->grpmask;
raw_spin_lock_rcu_node(rnp); /* irqs already disabled. */
if (!rdp->beenonline)
WRITE_ONCE(rsp->ncpus, READ_ONCE(rsp->ncpus) + 1);
@ -3872,7 +3964,7 @@ void rcu_cpu_starting(unsigned int cpu)
struct rcu_state *rsp;
for_each_rcu_flavor(rsp) {
rdp = this_cpu_ptr(rsp->rda);
rdp = per_cpu_ptr(rsp->rda, cpu);
rnp = rdp->mynode;
mask = rdp->grpmask;
raw_spin_lock_irqsave_rcu_node(rnp, flags);

15
kernel/rcu/tree.h
View File

@ -521,7 +521,6 @@ struct rcu_state {
struct mutex exp_mutex; /* Serialize expedited GP. */
struct mutex exp_wake_mutex; /* Serialize wakeup. */
unsigned long expedited_sequence; /* Take a ticket. */
atomic_long_t expedited_normal; /* # fallbacks to normal. */
atomic_t expedited_need_qs; /* # CPUs left to check in. */
struct swait_queue_head expedited_wq; /* Wait for check-ins. */
int ncpus_snap; /* # CPUs seen last time. */
@ -595,6 +594,8 @@ extern struct rcu_state rcu_bh_state;
extern struct rcu_state rcu_preempt_state;
#endif /* #ifdef CONFIG_PREEMPT_RCU */
int rcu_dynticks_snap(struct rcu_dynticks *rdtp);
#ifdef CONFIG_RCU_BOOST
DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
DECLARE_PER_CPU(int, rcu_cpu_kthread_cpu);
@ -687,18 +688,6 @@ static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll)
}
#endif /* #ifdef CONFIG_RCU_TRACE */
/*
* Place this after a lock-acquisition primitive to guarantee that
* an UNLOCK+LOCK pair act as a full barrier. This guarantee applies
* if the UNLOCK and LOCK are executed by the same CPU or if the
* UNLOCK and LOCK operate on the same lock variable.
*/
#ifdef CONFIG_PPC
#define smp_mb__after_unlock_lock() smp_mb() /* Full ordering for lock. */
#else /* #ifdef CONFIG_PPC */
#define smp_mb__after_unlock_lock() do { } while (0)
#endif /* #else #ifdef CONFIG_PPC */
/*
* Wrappers for the rcu_node::lock acquire and release.
*

38
kernel/rcu/tree_exp.h
View File

@ -20,16 +20,26 @@
* Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
*/
/* Wrapper functions for expedited grace periods. */
/*
* Record the start of an expedited grace period.
*/
static void rcu_exp_gp_seq_start(struct rcu_state *rsp)
{
rcu_seq_start(&rsp->expedited_sequence);
}
/*
* Record the end of an expedited grace period.
*/
static void rcu_exp_gp_seq_end(struct rcu_state *rsp)
{
rcu_seq_end(&rsp->expedited_sequence);
smp_mb(); /* Ensure that consecutive grace periods serialize. */
}
/*
* Take a snapshot of the expedited-grace-period counter.
*/
static unsigned long rcu_exp_gp_seq_snap(struct rcu_state *rsp)
{
unsigned long s;
@ -39,6 +49,12 @@ static unsigned long rcu_exp_gp_seq_snap(struct rcu_state *rsp)
trace_rcu_exp_grace_period(rsp->name, s, TPS("snap"));
return s;
}
/*
* Given a counter snapshot from rcu_exp_gp_seq_snap(), return true
* if a full expedited grace period has elapsed since that snapshot
* was taken.
*/
static bool rcu_exp_gp_seq_done(struct rcu_state *rsp, unsigned long s)
{
return rcu_seq_done(&rsp->expedited_sequence, s);
@ -356,12 +372,11 @@ static void sync_rcu_exp_select_cpus(struct rcu_state *rsp,
mask_ofl_test = 0;
for_each_leaf_node_possible_cpu(rnp, cpu) {
struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
rdp->exp_dynticks_snap =
atomic_add_return(0, &rdtp->dynticks);
rcu_dynticks_snap(rdp->dynticks);
if (raw_smp_processor_id() == cpu ||
!(rdp->exp_dynticks_snap & 0x1) ||
rcu_dynticks_in_eqs(rdp->exp_dynticks_snap) ||
!(rnp->qsmaskinitnext & rdp->grpmask))
mask_ofl_test |= rdp->grpmask;
}
@ -380,13 +395,12 @@ static void sync_rcu_exp_select_cpus(struct rcu_state *rsp,
for_each_leaf_node_possible_cpu(rnp, cpu) {
unsigned long mask = leaf_node_cpu_bit(rnp, cpu);
struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
if (!(mask_ofl_ipi & mask))
continue;
retry_ipi:
if (atomic_add_return(0, &rdtp->dynticks) !=
rdp->exp_dynticks_snap) {
if (rcu_dynticks_in_eqs_since(rdp->dynticks,
rdp->exp_dynticks_snap)) {
mask_ofl_test |= mask;
continue;
}
@ -623,6 +637,11 @@ void synchronize_sched_expedited(void)
{
struct rcu_state *rsp = &rcu_sched_state;
RCU_LOCKDEP_WARN(lock_is_held(&rcu_bh_lock_map) ||
lock_is_held(&rcu_lock_map) ||
lock_is_held(&rcu_sched_lock_map),
"Illegal synchronize_sched_expedited() in RCU read-side critical section");
/* If only one CPU, this is automatically a grace period. */
if (rcu_blocking_is_gp())
return;
@ -692,6 +711,11 @@ void synchronize_rcu_expedited(void)
{
struct rcu_state *rsp = rcu_state_p;
RCU_LOCKDEP_WARN(lock_is_held(&rcu_bh_lock_map) ||
lock_is_held(&rcu_lock_map) ||
lock_is_held(&rcu_sched_lock_map),
"Illegal synchronize_rcu_expedited() in RCU read-side critical section");
if (rcu_scheduler_active == RCU_SCHEDULER_INACTIVE)
return;
_synchronize_rcu_expedited(rsp, sync_rcu_exp_handler);

7
kernel/rcu/tree_plugin.h
View File

@ -1643,7 +1643,7 @@ static void print_cpu_stall_info(struct rcu_state *rsp, int cpu)
"o."[!!(rdp->grpmask & rdp->mynode->qsmaskinit)],
"N."[!!(rdp->grpmask & rdp->mynode->qsmaskinitnext)],
ticks_value, ticks_title,
atomic_read(&rdtp->dynticks) & 0xfff,
rcu_dynticks_snap(rdtp) & 0xfff,
rdtp->dynticks_nesting, rdtp->dynticks_nmi_nesting,
rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu),
READ_ONCE(rsp->n_force_qs) - rsp->n_force_qs_gpstart,
@ -2366,8 +2366,9 @@ static void __init rcu_organize_nocb_kthreads(struct rcu_state *rsp)
}
/*
* Each pass through this loop sets up one rcu_data structure and
* spawns one rcu_nocb_kthread().
* Each pass through this loop sets up one rcu_data structure.
* Should the corresponding CPU come online in the future, then
* we will spawn the needed set of rcu_nocb_kthread() kthreads.
*/
for_each_cpu(cpu, rcu_nocb_mask) {
rdp = per_cpu_ptr(rsp->rda, cpu);

5
kernel/rcu/tree_trace.c
View File

@ -124,7 +124,7 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
rdp->rcu_qs_ctr_snap == per_cpu(rcu_qs_ctr, rdp->cpu),
rdp->core_needs_qs);
seq_printf(m, " dt=%d/%llx/%d df=%lu",
atomic_read(&rdp->dynticks->dynticks),
rcu_dynticks_snap(rdp->dynticks),
rdp->dynticks->dynticks_nesting,
rdp->dynticks->dynticks_nmi_nesting,
rdp->dynticks_fqs);
@ -194,9 +194,8 @@ static int show_rcuexp(struct seq_file *m, void *v)
s2 += atomic_long_read(&rdp->exp_workdone2);
s3 += atomic_long_read(&rdp->exp_workdone3);
}
seq_printf(m, "s=%lu wd0=%lu wd1=%lu wd2=%lu wd3=%lu n=%lu enq=%d sc=%lu\n",
seq_printf(m, "s=%lu wd0=%lu wd1=%lu wd2=%lu wd3=%lu enq=%d sc=%lu\n",
rsp->expedited_sequence, s0, s1, s2, s3,
atomic_long_read(&rsp->expedited_normal),
atomic_read(&rsp->expedited_need_qs),
rsp->expedited_sequence / 2);
return 0;

4
kernel/rcu/update.c
View File

@ -132,8 +132,7 @@ bool rcu_gp_is_normal(void)
}
EXPORT_SYMBOL_GPL(rcu_gp_is_normal);
static atomic_t rcu_expedited_nesting =
ATOMIC_INIT(IS_ENABLED(CONFIG_RCU_EXPEDITE_BOOT) ? 1 : 0);
static atomic_t rcu_expedited_nesting = ATOMIC_INIT(1);
/*
* Should normal grace-period primitives be expedited? Intended for
@ -182,7 +181,6 @@ EXPORT_SYMBOL_GPL(rcu_unexpedite_gp);
*/
void rcu_end_inkernel_boot(void)
{
if (IS_ENABLED(CONFIG_RCU_EXPEDITE_BOOT))
rcu_unexpedite_gp();
if (rcu_normal_after_boot)
WRITE_ONCE(rcu_normal, 1);

1
lib/Kconfig.debug
View File

@ -1450,6 +1450,7 @@ config RCU_CPU_STALL_TIMEOUT
config RCU_TRACE
bool "Enable tracing for RCU"
depends on DEBUG_KERNEL
default y if TREE_RCU
select TRACE_CLOCK
help
This option provides tracing in RCU which presents stats

3
tools/testing/selftests/rcutorture/configs/rcu/CFcommon
View File

@ -1,5 +1,2 @@
CONFIG_RCU_TORTURE_TEST=y
CONFIG_PRINTK_TIME=y
CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP=y
CONFIG_RCU_TORTURE_TEST_SLOW_INIT=y
CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT=y

1
tools/testing/selftests/rcutorture/configs/rcu/TINY01
View File

@ -7,6 +7,7 @@ CONFIG_HZ_PERIODIC=n
CONFIG_NO_HZ_IDLE=y
CONFIG_NO_HZ_FULL=n
CONFIG_RCU_TRACE=n
#CHECK#CONFIG_RCU_STALL_COMMON=n
CONFIG_DEBUG_LOCK_ALLOC=n
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_PREEMPT_COUNT=n

3
tools/testing/selftests/rcutorture/configs/rcu/TINY02
View File

@ -8,7 +8,8 @@ CONFIG_NO_HZ_IDLE=n
CONFIG_NO_HZ_FULL=n
CONFIG_RCU_TRACE=y
CONFIG_PROVE_LOCKING=y
CONFIG_PROVE_RCU_REPEATEDLY=y
#CHECK#CONFIG_PROVE_RCU=y
CONFIG_DEBUG_LOCK_ALLOC=y
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_DEBUG_OBJECTS_RCU_HEAD=y
CONFIG_PREEMPT_COUNT=y

3
tools/testing/selftests/rcutorture/configs/rcu/TREE01
View File

@ -16,3 +16,6 @@ CONFIG_DEBUG_LOCK_ALLOC=n
CONFIG_RCU_BOOST=n
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_RCU_EXPERT=y
CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP=y
CONFIG_RCU_TORTURE_TEST_SLOW_INIT=y
CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT=y

4
tools/testing/selftests/rcutorture/configs/rcu/TREE02
View File

@ -20,3 +20,7 @@ CONFIG_PROVE_LOCKING=n
CONFIG_RCU_BOOST=n
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_RCU_EXPERT=y
CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP=y
CONFIG_RCU_TORTURE_TEST_SLOW_INIT=y
CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT=y
CONFIG_DEBUG_OBJECTS_RCU_HEAD=y

3
tools/testing/selftests/rcutorture/configs/rcu/TREE03
View File

@ -17,3 +17,6 @@ CONFIG_RCU_BOOST=y
CONFIG_RCU_KTHREAD_PRIO=2
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_RCU_EXPERT=y
CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP=y
CONFIG_RCU_TORTURE_TEST_SLOW_INIT=y
CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT=y

4
tools/testing/selftests/rcutorture/configs/rcu/TREE04
View File

@ -19,3 +19,7 @@ CONFIG_RCU_NOCB_CPU=n
CONFIG_DEBUG_LOCK_ALLOC=n
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_RCU_EXPERT=y
CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP=y
CONFIG_RCU_TORTURE_TEST_SLOW_INIT=y
CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT=y
CONFIG_RCU_EQS_DEBUG=y

3
tools/testing/selftests/rcutorture/configs/rcu/TREE05
View File

@ -19,3 +19,6 @@ CONFIG_PROVE_LOCKING=y
#CHECK#CONFIG_PROVE_RCU=y
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_RCU_EXPERT=y
CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP=y
CONFIG_RCU_TORTURE_TEST_SLOW_INIT=y
CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT=y

3
tools/testing/selftests/rcutorture/configs/rcu/TREE06
View File

@ -20,3 +20,6 @@ CONFIG_PROVE_LOCKING=y
#CHECK#CONFIG_PROVE_RCU=y
CONFIG_DEBUG_OBJECTS_RCU_HEAD=y
CONFIG_RCU_EXPERT=y
CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP=y
CONFIG_RCU_TORTURE_TEST_SLOW_INIT=y
CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT=y

3
tools/testing/selftests/rcutorture/configs/rcu/TREE07
View File

@ -19,3 +19,6 @@ CONFIG_RCU_NOCB_CPU=n
CONFIG_DEBUG_LOCK_ALLOC=n
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_RCU_EXPERT=y
CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP=y
CONFIG_RCU_TORTURE_TEST_SLOW_INIT=y
CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT=y

4
tools/testing/selftests/rcutorture/configs/rcu/TREE08
View File

@ -17,8 +17,8 @@ CONFIG_RCU_FANOUT_LEAF=2
CONFIG_RCU_NOCB_CPU=y
CONFIG_RCU_NOCB_CPU_ALL=y
CONFIG_DEBUG_LOCK_ALLOC=n
CONFIG_PROVE_LOCKING=y
#CHECK#CONFIG_PROVE_RCU=y
CONFIG_PROVE_LOCKING=n
CONFIG_RCU_BOOST=n
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_RCU_EXPERT=y
CONFIG_RCU_EQS_DEBUG=y

33
tools/testing/selftests/rcutorture/doc/TREE_RCU-kconfig.txt
View File

@ -14,6 +14,7 @@ CONFIG_NO_HZ_FULL_SYSIDLE -- Do one.
CONFIG_PREEMPT -- Do half. (First three and #8.)
CONFIG_PROVE_LOCKING -- Do several, covering CONFIG_DEBUG_LOCK_ALLOC=y and not.
CONFIG_PROVE_RCU -- Hardwired to CONFIG_PROVE_LOCKING.
CONFIG_PROVE_RCU_REPEATEDLY -- Do one.
CONFIG_RCU_BOOST -- one of PREEMPT_RCU.
CONFIG_RCU_KTHREAD_PRIO -- set to 2 for _BOOST testing.
CONFIG_RCU_FANOUT -- Cover hierarchy, but overlap with others.
@ -25,7 +26,12 @@ CONFIG_RCU_NOCB_CPU_NONE -- Do one.
CONFIG_RCU_NOCB_CPU_ZERO -- Do one.
CONFIG_RCU_TRACE -- Do half.
CONFIG_SMP -- Need one !SMP for PREEMPT_RCU.
!RCU_EXPERT -- Do a few, but these have to be vanilla configurations.
CONFIG_RCU_EXPERT=n -- Do a few, but these have to be vanilla configurations.
CONFIG_RCU_EQS_DEBUG -- Do at least one for CONFIG_NO_HZ_FULL and not.
CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP -- Do for all but a couple TREE scenarios.
CONFIG_RCU_TORTURE_TEST_SLOW_INIT -- Do for all but a couple TREE scenarios.
CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT -- Do for all but a couple TREE scenarios.
RCU-bh: Do one with PREEMPT and one with !PREEMPT.
RCU-sched: Do one with PREEMPT but not BOOST.
@ -72,7 +78,30 @@ CONFIG_RCU_TORTURE_TEST_RUNNABLE
Always used in KVM testing.
CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT_DELAY
CONFIG_RCU_TORTURE_TEST_SLOW_INIT_DELAY
CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY
Inspection suffices, ignore.
CONFIG_PREEMPT_RCU
CONFIG_TREE_RCU
CONFIG_TINY_RCU
These are controlled by CONFIG_PREEMPT.
These are controlled by CONFIG_PREEMPT and/or CONFIG_SMP.
CONFIG_SPARSE_RCU_POINTER
Makes sense only for sparse runs, not for kernel builds.
CONFIG_SRCU
CONFIG_TASKS_RCU
Selected by CONFIG_RCU_TORTURE_TEST, so cannot disable.
CONFIG_RCU_TRACE
Implied by CONFIG_RCU_TRACE for Tree RCU.
boot parameters ignored: TBD

1
tools/testing/selftests/rcutorture/formal/srcu-cbmc/.gitignore vendored Normal file
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@ -0,0 +1 @@
srcu.c

16
tools/testing/selftests/rcutorture/formal/srcu-cbmc/Makefile Normal file
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@ -0,0 +1,16 @@
all: srcu.c store_buffering
LINUX_SOURCE = ../../../../../..
modified_srcu_input = $(LINUX_SOURCE)/include/linux/srcu.h \
$(LINUX_SOURCE)/kernel/rcu/srcu.c
modified_srcu_output = include/linux/srcu.h srcu.c
include/linux/srcu.h: srcu.c
srcu.c: modify_srcu.awk Makefile $(modified_srcu_input)
awk -f modify_srcu.awk $(modified_srcu_input) $(modified_srcu_output)
store_buffering:
@cd tests/store_buffering; make

0
tools/testing/selftests/rcutorture/formal/srcu-cbmc/empty_includes/linux/delay.h Normal file
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0
tools/testing/selftests/rcutorture/formal/srcu-cbmc/empty_includes/linux/export.h Normal file
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0
tools/testing/selftests/rcutorture/formal/srcu-cbmc/empty_includes/linux/mutex.h Normal file
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0
tools/testing/selftests/rcutorture/formal/srcu-cbmc/empty_includes/linux/percpu.h Normal file
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0
tools/testing/selftests/rcutorture/formal/srcu-cbmc/empty_includes/linux/preempt.h Normal file
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0
tools/testing/selftests/rcutorture/formal/srcu-cbmc/empty_includes/linux/rcupdate.h Normal file
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0
tools/testing/selftests/rcutorture/formal/srcu-cbmc/empty_includes/linux/sched.h Normal file
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0
tools/testing/selftests/rcutorture/formal/srcu-cbmc/empty_includes/linux/smp.h Normal file
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0
tools/testing/selftests/rcutorture/formal/srcu-cbmc/empty_includes/linux/workqueue.h Normal file
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0
tools/testing/selftests/rcutorture/formal/srcu-cbmc/empty_includes/uapi/linux/types.h Normal file
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1
tools/testing/selftests/rcutorture/formal/srcu-cbmc/include/linux/.gitignore vendored Normal file
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@ -0,0 +1 @@
srcu.h

1
tools/testing/selftests/rcutorture/formal/srcu-cbmc/include/linux/kconfig.h Normal file
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@ -0,0 +1 @@
#include <LINUX_SOURCE/linux/kconfig.h>

155
tools/testing/selftests/rcutorture/formal/srcu-cbmc/include/linux/types.h Normal file
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@ -0,0 +1,155 @@
/*
* This header has been modifies to remove definitions of types that
* are defined in standard userspace headers or are problematic for some
* other reason.
*/
#ifndef _LINUX_TYPES_H
#define _LINUX_TYPES_H
#define __EXPORTED_HEADERS__
#include <uapi/linux/types.h>
#ifndef __ASSEMBLY__
#define DECLARE_BITMAP(name, bits) \
unsigned long name[BITS_TO_LONGS(bits)]
typedef __u32 __kernel_dev_t;
/* bsd */
typedef unsigned char u_char;
typedef unsigned short u_short;
typedef unsigned int u_int;
typedef unsigned long u_long;
/* sysv */
typedef unsigned char unchar;
typedef unsigned short ushort;
typedef unsigned int uint;
typedef unsigned long ulong;
#ifndef __BIT_TYPES_DEFINED__
#define __BIT_TYPES_DEFINED__
typedef __u8 u_int8_t;
typedef __s8 int8_t;
typedef __u16 u_int16_t;
typedef __s16 int16_t;
typedef __u32 u_int32_t;
typedef __s32 int32_t;
#endif /* !(__BIT_TYPES_DEFINED__) */
typedef __u8 uint8_t;
typedef __u16 uint16_t;
typedef __u32 uint32_t;
/* this is a special 64bit data type that is 8-byte aligned */
#define aligned_u64 __u64 __attribute__((aligned(8)))
#define aligned_be64 __be64 __attribute__((aligned(8)))
#define aligned_le64 __le64 __attribute__((aligned(8)))
/**
* The type used for indexing onto a disc or disc partition.
*
* Linux always considers sectors to be 512 bytes long independently
* of the devices real block size.
*
* blkcnt_t is the type of the inode's block count.
*/
#ifdef CONFIG_LBDAF
typedef u64 sector_t;
#else
typedef unsigned long sector_t;
#endif
/*
* The type of an index into the pagecache.
*/
#define pgoff_t unsigned long
/*
* A dma_addr_t can hold any valid DMA address, i.e., any address returned
* by the DMA API.
*
* If the DMA API only uses 32-bit addresses, dma_addr_t need only be 32
* bits wide. Bus addresses, e.g., PCI BARs, may be wider than 32 bits,
* but drivers do memory-mapped I/O to ioremapped kernel virtual addresses,
* so they don't care about the size of the actual bus addresses.
*/
#ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT
typedef u64 dma_addr_t;
#else
typedef u32 dma_addr_t;
#endif
#ifdef CONFIG_PHYS_ADDR_T_64BIT
typedef u64 phys_addr_t;
#else
typedef u32 phys_addr_t;
#endif
typedef phys_addr_t resource_size_t;
/*
* This type is the placeholder for a hardware interrupt number. It has to be
* big enough to enclose whatever representation is used by a given platform.
*/
typedef unsigned long irq_hw_number_t;
typedef struct {
int counter;
} atomic_t;
#ifdef CONFIG_64BIT
typedef struct {
long counter;
} atomic64_t;
#endif
struct list_head {
struct list_head *next, *prev;
};
struct hlist_head {
struct hlist_node *first;
};
struct hlist_node {
struct hlist_node *next, **pprev;
};
/**
* struct callback_head - callback structure for use with RCU and task_work
* @next: next update requests in a list
* @func: actual update function to call after the grace period.
*
* The struct is aligned to size of pointer. On most architectures it happens
* naturally due ABI requirements, but some architectures (like CRIS) have
* weird ABI and we need to ask it explicitly.
*
* The alignment is required to guarantee that bits 0 and 1 of @next will be
* clear under normal conditions -- as long as we use call_rcu(),
* call_rcu_bh(), call_rcu_sched(), or call_srcu() to queue callback.
*
* This guarantee is important for few reasons:
* - future call_rcu_lazy() will make use of lower bits in the pointer;
* - the structure shares storage spacer in struct page with @compound_head,
* which encode PageTail() in bit 0. The guarantee is needed to avoid
* false-positive PageTail().
*/
struct callback_head {
struct callback_head *next;
void (*func)(struct callback_head *head);
} __attribute__((aligned(sizeof(void *))));
#define rcu_head callback_head
typedef void (*rcu_callback_t)(struct rcu_head *head);
typedef void (*call_rcu_func_t)(struct rcu_head *head, rcu_callback_t func);
/* clocksource cycle base type */
typedef u64 cycle_t;
#endif /* __ASSEMBLY__ */
#endif /* _LINUX_TYPES_H */

375
tools/testing/selftests/rcutorture/formal/srcu-cbmc/modify_srcu.awk Executable file
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@ -0,0 +1,375 @@
#!/bin/awk -f
# Modify SRCU for formal verification. The first argument should be srcu.h and
# the second should be srcu.c. Outputs modified srcu.h and srcu.c into the
# current directory.
BEGIN {
if (ARGC != 5) {
print "Usange: input.h input.c output.h output.c" > "/dev/stderr";
exit 1;
}
h_output = ARGV[3];
c_output = ARGV[4];
ARGC = 3;
# Tokenize using FS and not RS as FS supports regular expressions. Each
# record is one line of source, except that backslashed lines are
# combined. Comments are treated as field separators, as are quotes.
quote_regexp="\"([^\\\\\"]|\\\\.)*\"";
comment_regexp="\\/\\*([^*]|\\*+[^*/])*\\*\\/|\\/\\/.*(\n|$)";
FS="([ \\\\\t\n\v\f;,.=(){}+*/<>&|^-]|\\[|\\]|" comment_regexp "|" quote_regexp ")+";
inside_srcu_struct = 0;
inside_srcu_init_def = 0;
srcu_init_param_name = "";
in_macro = 0;
brace_nesting = 0;
paren_nesting = 0;
# Allow the manipulation of the last field separator after has been
# seen.
last_fs = "";
# Whether the last field separator was intended to be output.
last_fs_print = 0;
# rcu_batches stores the initialization for each instance of struct
# rcu_batch
in_comment = 0;
outputfile = "";
}
{
prev_outputfile = outputfile;
if (FILENAME ~ /\.h$/) {
outputfile = h_output;
if (FNR != NR) {
print "Incorrect file order" > "/dev/stderr";
exit 1;
}
}
else
outputfile = c_output;
if (prev_outputfile && outputfile != prev_outputfile) {
new_outputfile = outputfile;
outputfile = prev_outputfile;
update_fieldsep("", 0);
outputfile = new_outputfile;
}
}
# Combine the next line into $0.
function combine_line() {
ret = getline next_line;
if (ret == 0) {
# Don't allow two consecutive getlines at the end of the file
if (eof_found) {
print "Error: expected more input." > "/dev/stderr";
exit 1;
} else {
eof_found = 1;
}
} else if (ret == -1) {
print "Error reading next line of file" FILENAME > "/dev/stderr";
exit 1;
}
$0 = $0 "\n" next_line;
}
# Combine backslashed lines and multiline comments.
function combine_backslashes() {
while (/\\$|\/\*([^*]|\*+[^*\/])*\**$/) {
combine_line();
}
}
function read_line() {
combine_line();
combine_backslashes();
}
# Print out field separators and update variables that depend on them. Only
# print if p is true. Call with sep="" and p=0 to print out the last field
# separator.
function update_fieldsep(sep, p) {
# Count braces
sep_tmp = sep;
gsub(quote_regexp "|" comment_regexp, "", sep_tmp);
while (1)
{
if (sub("[^{}()]*\\{", "", sep_tmp)) {
brace_nesting++;
continue;
}
if (sub("[^{}()]*\\}", "", sep_tmp)) {
brace_nesting--;
if (brace_nesting < 0) {
print "Unbalanced braces!" > "/dev/stderr";
exit 1;
}
continue;
}
if (sub("[^{}()]*\\(", "", sep_tmp)) {
paren_nesting++;
continue;
}
if (sub("[^{}()]*\\)", "", sep_tmp)) {
paren_nesting--;
if (paren_nesting < 0) {
print "Unbalanced parenthesis!" > "/dev/stderr";
exit 1;
}
continue;
}
break;
}
if (last_fs_print)
printf("%s", last_fs) > outputfile;
last_fs = sep;
last_fs_print = p;
}
# Shifts the fields down by n positions. Calls next if there are no more. If p
# is true then print out field separators.
function shift_fields(n, p) {
do {
if (match($0, FS) > 0) {
update_fieldsep(substr($0, RSTART, RLENGTH), p);
if (RSTART + RLENGTH <= length())
$0 = substr($0, RSTART + RLENGTH);
else
$0 = "";
} else {
update_fieldsep("", 0);
print "" > outputfile;
next;
}
} while (--n > 0);
}
# Shifts and prints the first n fields.
function print_fields(n) {
do {
update_fieldsep("", 0);
printf("%s", $1) > outputfile;
shift_fields(1, 1);
} while (--n > 0);
}
{
combine_backslashes();
}
# Print leading FS
{
if (match($0, "^(" FS ")+") > 0) {
update_fieldsep(substr($0, RSTART, RLENGTH), 1);
if (RSTART + RLENGTH <= length())
$0 = substr($0, RSTART + RLENGTH);
else
$0 = "";
}
}
# Parse the line.
{
while (NF > 0) {
if ($1 == "struct" && NF < 3) {
read_line();
continue;
}
if (FILENAME ~ /\.h$/ && !inside_srcu_struct &&
brace_nesting == 0 && paren_nesting == 0 &&
$1 == "struct" && $2 == "srcu_struct" &&
$0 ~ "^struct(" FS ")+srcu_struct(" FS ")+\\{") {
inside_srcu_struct = 1;
print_fields(2);
continue;
}
if (inside_srcu_struct && brace_nesting == 0 &&
paren_nesting == 0) {
inside_srcu_struct = 0;
update_fieldsep("", 0);
for (name in rcu_batches)
print "extern struct rcu_batch " name ";" > outputfile;
}
if (inside_srcu_struct && $1 == "struct" && $2 == "rcu_batch") {
# Move rcu_batches outside of the struct.
rcu_batches[$3] = "";
shift_fields(3, 1);
sub(/;[[:space:]]*$/, "", last_fs);
continue;
}
if (FILENAME ~ /\.h$/ && !inside_srcu_init_def &&
$1 == "#define" && $2 == "__SRCU_STRUCT_INIT") {
inside_srcu_init_def = 1;
srcu_init_param_name = $3;
in_macro = 1;
print_fields(3);
continue;
}
if (inside_srcu_init_def && brace_nesting == 0 &&
paren_nesting == 0) {
inside_srcu_init_def = 0;
in_macro = 0;
continue;
}
if (inside_srcu_init_def && brace_nesting == 1 &&
paren_nesting == 0 && last_fs ~ /\.[[:space:]]*$/ &&
$1 ~ /^[[:alnum:]_]+$/) {
name = $1;
if (name in rcu_batches) {
# Remove the dot.
sub(/\.[[:space:]]*$/, "", last_fs);
old_record = $0;
do
shift_fields(1, 0);
while (last_fs !~ /,/ || paren_nesting > 0);
end_loc = length(old_record) - length($0);
end_loc += index(last_fs, ",") - length(last_fs);
last_fs = substr(last_fs, index(last_fs, ",") + 1);
last_fs_print = 1;
match(old_record, "^"name"("FS")+=");
start_loc = RSTART + RLENGTH;
len = end_loc - start_loc;
initializer = substr(old_record, start_loc, len);
gsub(srcu_init_param_name "\\.", "", initializer);
rcu_batches[name] = initializer;
continue;
}
}
# Don't include a nonexistent file
if (!in_macro && $1 == "#include" && /^#include[[:space:]]+"rcu\.h"/) {
update_fieldsep("", 0);
next;
}
# Ignore most preprocessor stuff.
if (!in_macro && $1 ~ /#/) {
break;
}
if (brace_nesting > 0 && $1 ~ "^[[:alnum:]_]+$" && NF < 2) {
read_line();
continue;
}
if (brace_nesting > 0 &&
$0 ~ "^[[:alnum:]_]+[[:space:]]*(\\.|->)[[:space:]]*[[:alnum:]_]+" &&
$2 in rcu_batches) {
# Make uses of rcu_batches global. Somewhat unreliable.
shift_fields(1, 0);
print_fields(1);
continue;
}
if ($1 == "static" && NF < 3) {
read_line();
continue;
}
if ($1 == "static" && ($2 == "bool" && $3 == "try_check_zero" ||
$2 == "void" && $3 == "srcu_flip")) {
shift_fields(1, 1);
print_fields(2);
continue;
}
# Distinguish between read-side and write-side memory barriers.
if ($1 == "smp_mb" && NF < 2) {
read_line();
continue;
}
if (match($0, /^smp_mb[[:space:]();\/*]*[[:alnum:]]/)) {
barrier_letter = substr($0, RLENGTH, 1);
if (barrier_letter ~ /A|D/)
new_barrier_name = "sync_smp_mb";
else if (barrier_letter ~ /B|C/)
new_barrier_name = "rs_smp_mb";
else {
print "Unrecognized memory barrier." > "/dev/null";
exit 1;
}
shift_fields(1, 1);
printf("%s", new_barrier_name) > outputfile;
continue;
}
# Skip definition of rcu_synchronize, since it is already
# defined in misc.h. Only present in old versions of srcu.
if (brace_nesting == 0 && paren_nesting == 0 &&
$1 == "struct" && $2 == "rcu_synchronize" &&
$0 ~ "^struct(" FS ")+rcu_synchronize(" FS ")+\\{") {
shift_fields(2, 0);
while (brace_nesting) {
if (NF < 2)
read_line();
shift_fields(1, 0);
}
}
# Skip definition of wakeme_after_rcu for the same reason
if (brace_nesting == 0 && $1 == "static" && $2 == "void" &&
$3 == "wakeme_after_rcu") {
while (NF < 5)
read_line();
shift_fields(3, 0);
do {
while (NF < 3)
read_line();
shift_fields(1, 0);
} while (paren_nesting || brace_nesting);
}
if ($1 ~ /^(unsigned|long)$/ && NF < 3) {
read_line();
continue;
}
# Give srcu_batches_completed the correct type for old SRCU.
if (brace_nesting == 0 && $1 == "long" &&
$2 == "srcu_batches_completed") {
update_fieldsep("", 0);
printf("unsigned ") > outputfile;
print_fields(2);
continue;
}
if (brace_nesting == 0 && $1 == "unsigned" && $2 == "long" &&
$3 == "srcu_batches_completed") {
print_fields(3);
continue;
}
# Just print out the input code by default.
print_fields(1);
}
update_fieldsep("", 0);
print > outputfile;
next;
}
END {
update_fieldsep("", 0);
if (brace_nesting != 0) {
print "Unbalanced braces!" > "/dev/stderr";
exit 1;
}
# Define the rcu_batches
for (name in rcu_batches)
print "struct rcu_batch " name " = " rcu_batches[name] ";" > c_output;
}

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#ifndef ASSUME_H
#define ASSUME_H
/* Provide an assumption macro that can be disabled for gcc. */
#ifdef RUN
#define assume(x) \
do { \
/* Evaluate x to suppress warnings. */ \
(void) (x); \
} while (0)
#else
#define assume(x) __CPROVER_assume(x)
#endif
#endif

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#ifndef BARRIERS_H
#define BARRIERS_H
#define barrier() __asm__ __volatile__("" : : : "memory")
#ifdef RUN
#define smp_mb() __sync_synchronize()
#define smp_mb__after_unlock_lock() __sync_synchronize()
#else
/*
* Copied from CBMC's implementation of __sync_synchronize(), which
* seems to be disabled by default.
*/
#define smp_mb() __CPROVER_fence("WWfence", "RRfence", "RWfence", "WRfence", \
"WWcumul", "RRcumul", "RWcumul", "WRcumul")
#define smp_mb__after_unlock_lock() __CPROVER_fence("WWfence", "RRfence", "RWfence", "WRfence", \
"WWcumul", "RRcumul", "RWcumul", "WRcumul")
#endif
/*
* Allow memory barriers to be disabled in either the read or write side
* of SRCU individually.
*/
#ifndef NO_SYNC_SMP_MB
#define sync_smp_mb() smp_mb()
#else
#define sync_smp_mb() do {} while (0)
#endif
#ifndef NO_READ_SIDE_SMP_MB
#define rs_smp_mb() smp_mb()
#else
#define rs_smp_mb() do {} while (0)
#endif
#define ACCESS_ONCE(x) (*(volatile typeof(x) *) &(x))
#define READ_ONCE(x) ACCESS_ONCE(x)
#define WRITE_ONCE(x, val) (ACCESS_ONCE(x) = (val))
#endif

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#ifndef BUG_ON_H
#define BUG_ON_H
#include <assert.h>
#define BUG() assert(0)
#define BUG_ON(x) assert(!(x))
/* Does it make sense to treat warnings as errors? */
#define WARN() BUG()
#define WARN_ON(x) (BUG_ON(x), false)
#endif

13
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#include <config.h>
/* Include all source files. */
#include "include_srcu.c"
#include "preempt.c"
#include "misc.c"
/* Used by test.c files */
#include <pthread.h>
#include <stdlib.h>
#include <linux/srcu.h>

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/* "Cheater" definitions based on restricted Kconfig choices. */
#undef CONFIG_TINY_RCU
#undef __CHECKER__
#undef CONFIG_DEBUG_LOCK_ALLOC
#undef CONFIG_DEBUG_OBJECTS_RCU_HEAD
#undef CONFIG_HOTPLUG_CPU
#undef CONFIG_MODULES
#undef CONFIG_NO_HZ_FULL_SYSIDLE
#undef CONFIG_PREEMPT_COUNT
#undef CONFIG_PREEMPT_RCU
#undef CONFIG_PROVE_RCU
#undef CONFIG_RCU_NOCB_CPU
#undef CONFIG_RCU_NOCB_CPU_ALL
#undef CONFIG_RCU_STALL_COMMON
#undef CONFIG_RCU_TRACE
#undef CONFIG_RCU_USER_QS
#undef CONFIG_TASKS_RCU
#define CONFIG_TREE_RCU
#define CONFIG_GENERIC_ATOMIC64
#if NR_CPUS > 1
#define CONFIG_SMP
#else
#undef CONFIG_SMP
#endif

31
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#include <config.h>
#include <assert.h>
#include <errno.h>
#include <inttypes.h>
#include <pthread.h>
#include <stddef.h>
#include <string.h>
#include <sys/types.h>
#include "int_typedefs.h"
#include "barriers.h"
#include "bug_on.h"
#include "locks.h"
#include "misc.h"
#include "preempt.h"
#include "percpu.h"
#include "workqueues.h"
#ifdef USE_SIMPLE_SYNC_SRCU
#define synchronize_srcu(sp) synchronize_srcu_original(sp)
#endif
#include <srcu.c>
#ifdef USE_SIMPLE_SYNC_SRCU
#undef synchronize_srcu
#include "simple_sync_srcu.c"
#endif

33
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#ifndef INT_TYPEDEFS_H
#define INT_TYPEDEFS_H
#include <inttypes.h>
typedef int8_t s8;
typedef uint8_t u8;
typedef int16_t s16;
typedef uint16_t u16;
typedef int32_t s32;
typedef uint32_t u32;
typedef int64_t s64;
typedef uint64_t u64;
typedef int8_t __s8;
typedef uint8_t __u8;
typedef int16_t __s16;
typedef uint16_t __u16;
typedef int32_t __s32;
typedef uint32_t __u32;
typedef int64_t __s64;
typedef uint64_t __u64;
#define S8_C(x) INT8_C(x)
#define U8_C(x) UINT8_C(x)
#define S16_C(x) INT16_C(x)
#define U16_C(x) UINT16_C(x)
#define S32_C(x) INT32_C(x)
#define U32_C(x) UINT32_C(x)
#define S64_C(x) INT64_C(x)
#define U64_C(x) UINT64_C(x)
#endif

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#ifndef LOCKS_H
#define LOCKS_H
#include <limits.h>
#include <pthread.h>
#include <stdbool.h>
#include "assume.h"
#include "bug_on.h"
#include "preempt.h"
int nondet_int(void);
#define __acquire(x)
#define __acquires(x)
#define __release(x)
#define __releases(x)
/* Only use one lock mechanism. Select which one. */
#ifdef PTHREAD_LOCK
struct lock_impl {
pthread_mutex_t mutex;
};
static inline void lock_impl_lock(struct lock_impl *lock)
{
BUG_ON(pthread_mutex_lock(&lock->mutex));
}
static inline void lock_impl_unlock(struct lock_impl *lock)
{
BUG_ON(pthread_mutex_unlock(&lock->mutex));
}
static inline bool lock_impl_trylock(struct lock_impl *lock)
{
int err = pthread_mutex_trylock(&lock->mutex);
if (!err)
return true;
else if (err == EBUSY)
return false;
BUG();
}
static inline void lock_impl_init(struct lock_impl *lock)
{
pthread_mutex_init(&lock->mutex, NULL);
}
#define LOCK_IMPL_INITIALIZER {.mutex = PTHREAD_MUTEX_INITIALIZER}
#else /* !defined(PTHREAD_LOCK) */
/* Spinlock that assumes that it always gets the lock immediately. */
struct lock_impl {
bool locked;
};
static inline bool lock_impl_trylock(struct lock_impl *lock)
{
#ifdef RUN
/* TODO: Should this be a test and set? */
return __sync_bool_compare_and_swap(&lock->locked, false, true);
#else
__CPROVER_atomic_begin();
bool old_locked = lock->locked;
lock->locked = true;
__CPROVER_atomic_end();
/* Minimal barrier to prevent accesses leaking out of lock. */
__CPROVER_fence("RRfence", "RWfence");
return !old_locked;
#endif
}
static inline void lock_impl_lock(struct lock_impl *lock)
{
/*
* CBMC doesn't support busy waiting, so just assume that the
* lock is available.
*/
assume(lock_impl_trylock(lock));
/*
* If the lock was already held by this thread then the assumption
* is unsatisfiable (deadlock).
*/
}
static inline void lock_impl_unlock(struct lock_impl *lock)
{
#ifdef RUN
BUG_ON(!__sync_bool_compare_and_swap(&lock->locked, true, false));
#else
/* Minimal barrier to prevent accesses leaking out of lock. */
__CPROVER_fence("RWfence", "WWfence");
__CPROVER_atomic_begin();
bool old_locked = lock->locked;
lock->locked = false;
__CPROVER_atomic_end();
BUG_ON(!old_locked);
#endif
}
static inline void lock_impl_init(struct lock_impl *lock)
{
lock->locked = false;
}
#define LOCK_IMPL_INITIALIZER {.locked = false}
#endif /* !defined(PTHREAD_LOCK) */
/*
* Implement spinlocks using the lock mechanism. Wrap the lock to prevent mixing
* locks of different types.
*/
typedef struct {
struct lock_impl internal_lock;
} spinlock_t;
#define SPIN_LOCK_UNLOCKED {.internal_lock = LOCK_IMPL_INITIALIZER}
#define __SPIN_LOCK_UNLOCKED(x) SPIN_LOCK_UNLOCKED
#define DEFINE_SPINLOCK(x) spinlock_t x = SPIN_LOCK_UNLOCKED
static inline void spin_lock_init(spinlock_t *lock)
{
lock_impl_init(&lock->internal_lock);
}
static inline void spin_lock(spinlock_t *lock)
{
/*
* Spin locks also need to be removed in order to eliminate all
* memory barriers. They are only used by the write side anyway.
*/
#ifndef NO_SYNC_SMP_MB
preempt_disable();
lock_impl_lock(&lock->internal_lock);
#endif
}
static inline void spin_unlock(spinlock_t *lock)
{
#ifndef NO_SYNC_SMP_MB
lock_impl_unlock(&lock->internal_lock);
preempt_enable();
#endif
}
/* Don't bother with interrupts */
#define spin_lock_irq(lock) spin_lock(lock)
#define spin_unlock_irq(lock) spin_unlock(lock)
#define spin_lock_irqsave(lock, flags) spin_lock(lock)
#define spin_unlock_irqrestore(lock, flags) spin_unlock(lock)
/*
* This is supposed to return an int, but I think that a bool should work as
* well.
*/
static inline bool spin_trylock(spinlock_t *lock)
{
#ifndef NO_SYNC_SMP_MB
preempt_disable();
return lock_impl_trylock(&lock->internal_lock);
#else
return true;
#endif
}
struct completion {
/* Hopefuly this won't overflow. */
unsigned int count;
};
#define COMPLETION_INITIALIZER(x) {.count = 0}
#define DECLARE_COMPLETION(x) struct completion x = COMPLETION_INITIALIZER(x)
#define DECLARE_COMPLETION_ONSTACK(x) DECLARE_COMPLETION(x)
static inline void init_completion(struct completion *c)
{
c->count = 0;
}
static inline void wait_for_completion(struct completion *c)
{
unsigned int prev_count = __sync_fetch_and_sub(&c->count, 1);
assume(prev_count);
}
static inline void complete(struct completion *c)
{
unsigned int prev_count = __sync_fetch_and_add(&c->count, 1);
BUG_ON(prev_count == UINT_MAX);
}
/* This function probably isn't very useful for CBMC. */
static inline bool try_wait_for_completion(struct completion *c)
{
BUG();
}
static inline bool completion_done(struct completion *c)
{
return c->count;
}
/* TODO: Implement complete_all */
static inline void complete_all(struct completion *c)
{
BUG();
}
#endif

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#include <config.h>
#include "misc.h"
#include "bug_on.h"
struct rcu_head;
void wakeme_after_rcu(struct rcu_head *head)
{
BUG();
}

58
tools/testing/selftests/rcutorture/formal/srcu-cbmc/src/misc.h Normal file
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#ifndef MISC_H
#define MISC_H
#include "assume.h"
#include "int_typedefs.h"
#include "locks.h"
#include <linux/types.h>
/* Probably won't need to deal with bottom halves. */
static inline void local_bh_disable(void) {}
static inline void local_bh_enable(void) {}
#define MODULE_ALIAS(X)
#define module_param(...)
#define EXPORT_SYMBOL_GPL(x)
#define container_of(ptr, type, member) ({ \
const typeof(((type *)0)->member) *__mptr = (ptr); \
(type *)((char *)__mptr - offsetof(type, member)); \
})
#ifndef USE_SIMPLE_SYNC_SRCU
/* Abuse udelay to make sure that busy loops terminate. */
#define udelay(x) assume(0)
#else
/* The simple custom synchronize_srcu is ok with try_check_zero failing. */
#define udelay(x) do { } while (0)
#endif
#define trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \
do { } while (0)
#define notrace
/* Avoid including rcupdate.h */
struct rcu_synchronize {
struct rcu_head head;
struct completion completion;
};
void wakeme_after_rcu(struct rcu_head *head);
#define rcu_lock_acquire(a) do { } while (0)
#define rcu_lock_release(a) do { } while (0)
#define rcu_lockdep_assert(c, s) do { } while (0)
#define RCU_LOCKDEP_WARN(c, s) do { } while (0)
/* Let CBMC non-deterministically choose switch between normal and expedited. */
bool rcu_gp_is_normal(void);
bool rcu_gp_is_expedited(void);
/* Do the same for old versions of rcu. */
#define rcu_expedited (rcu_gp_is_expedited())
#endif

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#ifndef PERCPU_H
#define PERCPU_H
#include <stddef.h>
#include "bug_on.h"
#include "preempt.h"
#define __percpu
/* Maximum size of any percpu data. */
#define PERCPU_OFFSET (4 * sizeof(long))
/* Ignore alignment, as CBMC doesn't care about false sharing. */
#define alloc_percpu(type) __alloc_percpu(sizeof(type), 1)
static inline void *__alloc_percpu(size_t size, size_t align)
{
BUG();
return NULL;
}
static inline void free_percpu(void *ptr)
{
BUG();
}
#define per_cpu_ptr(ptr, cpu) \
((typeof(ptr)) ((char *) (ptr) + PERCPU_OFFSET * cpu))
#define __this_cpu_inc(pcp) __this_cpu_add(pcp, 1)
#define __this_cpu_dec(pcp) __this_cpu_sub(pcp, 1)
#define __this_cpu_sub(pcp, n) __this_cpu_add(pcp, -(typeof(pcp)) (n))
#define this_cpu_inc(pcp) this_cpu_add(pcp, 1)
#define this_cpu_dec(pcp) this_cpu_sub(pcp, 1)
#define this_cpu_sub(pcp, n) this_cpu_add(pcp, -(typeof(pcp)) (n))
/* Make CBMC use atomics to work around bug. */
#ifdef RUN
#define THIS_CPU_ADD_HELPER(ptr, x) (*(ptr) += (x))
#else
/*
* Split the atomic into a read and a write so that it has the least
* possible ordering.
*/
#define THIS_CPU_ADD_HELPER(ptr, x) \
do { \
typeof(ptr) this_cpu_add_helper_ptr = (ptr); \
typeof(ptr) this_cpu_add_helper_x = (x); \
typeof(*ptr) this_cpu_add_helper_temp; \
__CPROVER_atomic_begin(); \
this_cpu_add_helper_temp = *(this_cpu_add_helper_ptr); \
__CPROVER_atomic_end(); \
this_cpu_add_helper_temp += this_cpu_add_helper_x; \
__CPROVER_atomic_begin(); \
*(this_cpu_add_helper_ptr) = this_cpu_add_helper_temp; \
__CPROVER_atomic_end(); \
} while (0)
#endif
/*
* For some reason CBMC needs an atomic operation even though this is percpu
* data.
*/
#define __this_cpu_add(pcp, n) \
do { \
BUG_ON(preemptible()); \
THIS_CPU_ADD_HELPER(per_cpu_ptr(&(pcp), thread_cpu_id), \
(typeof(pcp)) (n)); \
} while (0)
#define this_cpu_add(pcp, n) \
do { \
int this_cpu_add_impl_cpu = get_cpu(); \
THIS_CPU_ADD_HELPER(per_cpu_ptr(&(pcp), this_cpu_add_impl_cpu), \
(typeof(pcp)) (n)); \
put_cpu(); \
} while (0)
/*
* This will cause a compiler warning because of the cast from char[][] to
* type*. This will cause a compile time error if type is too big.
*/
#define DEFINE_PER_CPU(type, name) \
char name[NR_CPUS][PERCPU_OFFSET]; \
typedef char percpu_too_big_##name \
[sizeof(type) > PERCPU_OFFSET ? -1 : 1]
#define for_each_possible_cpu(cpu) \
for ((cpu) = 0; (cpu) < NR_CPUS; ++(cpu))
#endif

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#include <config.h>
#include "preempt.h"
#include "assume.h"
#include "locks.h"
/* Support NR_CPUS of at most 64 */
#define CPU_PREEMPTION_LOCKS_INIT0 LOCK_IMPL_INITIALIZER
#define CPU_PREEMPTION_LOCKS_INIT1 \
CPU_PREEMPTION_LOCKS_INIT0, CPU_PREEMPTION_LOCKS_INIT0
#define CPU_PREEMPTION_LOCKS_INIT2 \
CPU_PREEMPTION_LOCKS_INIT1, CPU_PREEMPTION_LOCKS_INIT1
#define CPU_PREEMPTION_LOCKS_INIT3 \
CPU_PREEMPTION_LOCKS_INIT2, CPU_PREEMPTION_LOCKS_INIT2
#define CPU_PREEMPTION_LOCKS_INIT4 \
CPU_PREEMPTION_LOCKS_INIT3, CPU_PREEMPTION_LOCKS_INIT3
#define CPU_PREEMPTION_LOCKS_INIT5 \
CPU_PREEMPTION_LOCKS_INIT4, CPU_PREEMPTION_LOCKS_INIT4
/*
* Simulate disabling preemption by locking a particular cpu. NR_CPUS
* should be the actual number of cpus, not just the maximum.
*/
struct lock_impl cpu_preemption_locks[NR_CPUS] = {
CPU_PREEMPTION_LOCKS_INIT0
#if (NR_CPUS - 1) & 1
, CPU_PREEMPTION_LOCKS_INIT0
#endif
#if (NR_CPUS - 1) & 2
, CPU_PREEMPTION_LOCKS_INIT1
#endif
#if (NR_CPUS - 1) & 4
, CPU_PREEMPTION_LOCKS_INIT2
#endif
#if (NR_CPUS - 1) & 8
, CPU_PREEMPTION_LOCKS_INIT3
#endif
#if (NR_CPUS - 1) & 16
, CPU_PREEMPTION_LOCKS_INIT4
#endif
#if (NR_CPUS - 1) & 32
, CPU_PREEMPTION_LOCKS_INIT5
#endif
};
#undef CPU_PREEMPTION_LOCKS_INIT0
#undef CPU_PREEMPTION_LOCKS_INIT1
#undef CPU_PREEMPTION_LOCKS_INIT2
#undef CPU_PREEMPTION_LOCKS_INIT3
#undef CPU_PREEMPTION_LOCKS_INIT4
#undef CPU_PREEMPTION_LOCKS_INIT5
__thread int thread_cpu_id;
__thread int preempt_disable_count;
void preempt_disable(void)
{
BUG_ON(preempt_disable_count < 0 || preempt_disable_count == INT_MAX);
if (preempt_disable_count++)
return;
thread_cpu_id = nondet_int();
assume(thread_cpu_id >= 0);
assume(thread_cpu_id < NR_CPUS);
lock_impl_lock(&cpu_preemption_locks[thread_cpu_id]);
}
void preempt_enable(void)
{
BUG_ON(preempt_disable_count < 1);
if (--preempt_disable_count)
return;
lock_impl_unlock(&cpu_preemption_locks[thread_cpu_id]);
}

58
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#ifndef PREEMPT_H
#define PREEMPT_H
#include <stdbool.h>
#include "bug_on.h"
/* This flag contains garbage if preempt_disable_count is 0. */
extern __thread int thread_cpu_id;
/* Support recursive preemption disabling. */
extern __thread int preempt_disable_count;
void preempt_disable(void);
void preempt_enable(void);
static inline void preempt_disable_notrace(void)
{
preempt_disable();
}
static inline void preempt_enable_no_resched(void)
{
preempt_enable();
}
static inline void preempt_enable_notrace(void)
{
preempt_enable();
}
static inline int preempt_count(void)
{
return preempt_disable_count;
}
static inline bool preemptible(void)
{
return !preempt_count();
}
static inline int get_cpu(void)
{
preempt_disable();
return thread_cpu_id;
}
static inline void put_cpu(void)
{
preempt_enable();
}
static inline void might_sleep(void)
{
BUG_ON(preempt_disable_count);
}
#endif

50
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#include <config.h>
#include <assert.h>
#include <errno.h>
#include <inttypes.h>
#include <pthread.h>
#include <stddef.h>
#include <string.h>
#include <sys/types.h>
#include "int_typedefs.h"
#include "barriers.h"
#include "bug_on.h"
#include "locks.h"
#include "misc.h"
#include "preempt.h"
#include "percpu.h"
#include "workqueues.h"
#include <linux/srcu.h>
/* Functions needed from modify_srcu.c */
bool try_check_zero(struct srcu_struct *sp, int idx, int trycount);
void srcu_flip(struct srcu_struct *sp);
/* Simpler implementation of synchronize_srcu that ignores batching. */
void synchronize_srcu(struct srcu_struct *sp)
{
int idx;
/*
* This code assumes that try_check_zero will succeed anyway,
* so there is no point in multiple tries.
*/
const int trycount = 1;
might_sleep();
/* Ignore the lock, as multiple writers aren't working yet anyway. */
idx = 1 ^ (sp->completed & 1);
/* For comments see srcu_advance_batches. */
assume(try_check_zero(sp, idx, trycount));
srcu_flip(sp);
assume(try_check_zero(sp, idx^1, trycount));
}

102
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#ifndef WORKQUEUES_H
#define WORKQUEUES_H
#include <stdbool.h>
#include "barriers.h"
#include "bug_on.h"
#include "int_typedefs.h"
#include <linux/types.h>
/* Stub workqueue implementation. */
struct work_struct;
typedef void (*work_func_t)(struct work_struct *work);
void delayed_work_timer_fn(unsigned long __data);
struct work_struct {
/* atomic_long_t data; */
unsigned long data;
struct list_head entry;
work_func_t func;
#ifdef CONFIG_LOCKDEP
struct lockdep_map lockdep_map;
#endif
};
struct timer_list {
struct hlist_node entry;
unsigned long expires;
void (*function)(unsigned long);
unsigned long data;
u32 flags;
int slack;
};
struct delayed_work {
struct work_struct work;
struct timer_list timer;
/* target workqueue and CPU ->timer uses to queue ->work */
struct workqueue_struct *wq;
int cpu;
};
static inline bool schedule_work(struct work_struct *work)
{
BUG();
return true;
}
static inline bool schedule_work_on(int cpu, struct work_struct *work)
{
BUG();
return true;
}
static inline bool queue_work(struct workqueue_struct *wq,
struct work_struct *work)
{
BUG();
return true;
}
static inline bool queue_delayed_work(struct workqueue_struct *wq,
struct delayed_work *dwork,
unsigned long delay)
{
BUG();
return true;
}
#define INIT_WORK(w, f) \
do { \
(w)->data = 0; \
(w)->func = (f); \
} while (0)
#define INIT_DELAYED_WORK(w, f) INIT_WORK(&(w)->work, (f))
#define __WORK_INITIALIZER(n, f) { \
.data = 0, \
.entry = { &(n).entry, &(n).entry }, \
.func = f \
}
/* Don't bother initializing timer. */
#define __DELAYED_WORK_INITIALIZER(n, f, tflags) { \
.work = __WORK_INITIALIZER((n).work, (f)), \
}
#define DECLARE_WORK(n, f) \
struct workqueue_struct n = __WORK_INITIALIZER
#define DECLARE_DELAYED_WORK(n, f) \
struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, 0)
#define system_power_efficient_wq ((struct workqueue_struct *) NULL)
#endif

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tools/testing/selftests/rcutorture/formal/srcu-cbmc/tests/store_buffering/.gitignore vendored Normal file
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*.out

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tools/testing/selftests/rcutorture/formal/srcu-cbmc/tests/store_buffering/Makefile Normal file
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CBMC_FLAGS = -I../.. -I../../src -I../../include -I../../empty_includes -32 -pointer-check -mm pso
all:
for i in ./*.pass; do \
echo $$i ; \
CBMC_FLAGS="$(CBMC_FLAGS)" sh ../test_script.sh --should-pass $$i > $$i.out 2>&1 ; \
done
for i in ./*.fail; do \
echo $$i ; \
CBMC_FLAGS="$(CBMC_FLAGS)" sh ../test_script.sh --should-fail $$i > $$i.out 2>&1 ; \
done

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tools/testing/selftests/rcutorture/formal/srcu-cbmc/tests/store_buffering/assert_end.fail Normal file
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test_cbmc_options="-DASSERT_END"

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tools/testing/selftests/rcutorture/formal/srcu-cbmc/tests/store_buffering/force.fail Normal file
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test_cbmc_options="-DFORCE_FAILURE"

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tools/testing/selftests/rcutorture/formal/srcu-cbmc/tests/store_buffering/force2.fail Normal file
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test_cbmc_options="-DFORCE_FAILURE_2"

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tools/testing/selftests/rcutorture/formal/srcu-cbmc/tests/store_buffering/force3.fail Normal file
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test_cbmc_options="-DFORCE_FAILURE_3"

0
tools/testing/selftests/rcutorture/formal/srcu-cbmc/tests/store_buffering/main.pass Normal file
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72
tools/testing/selftests/rcutorture/formal/srcu-cbmc/tests/store_buffering/test.c Normal file
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#include <src/combined_source.c>
int x;
int y;
int __unbuffered_tpr_x;
int __unbuffered_tpr_y;
DEFINE_SRCU(ss);
void rcu_reader(void)
{
int idx;
#ifndef FORCE_FAILURE_3
idx = srcu_read_lock(&ss);
#endif
might_sleep();
__unbuffered_tpr_y = READ_ONCE(y);
#ifdef FORCE_FAILURE
srcu_read_unlock(&ss, idx);
idx = srcu_read_lock(&ss);
#endif
WRITE_ONCE(x, 1);
#ifndef FORCE_FAILURE_3
srcu_read_unlock(&ss, idx);
#endif
might_sleep();
}
void *thread_update(void *arg)
{
WRITE_ONCE(y, 1);
#ifndef FORCE_FAILURE_2
synchronize_srcu(&ss);
#endif
might_sleep();
__unbuffered_tpr_x = READ_ONCE(x);
return NULL;
}
void *thread_process_reader(void *arg)
{
rcu_reader();
return NULL;
}
int main(int argc, char *argv[])
{
pthread_t tu;
pthread_t tpr;
if (pthread_create(&tu, NULL, thread_update, NULL))
abort();
if (pthread_create(&tpr, NULL, thread_process_reader, NULL))
abort();
if (pthread_join(tu, NULL))
abort();
if (pthread_join(tpr, NULL))
abort();
assert(__unbuffered_tpr_y != 0 || __unbuffered_tpr_x != 0);
#ifdef ASSERT_END
assert(0);
#endif
return 0;
}

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#!/bin/sh
# This script expects a mode (either --should-pass or --should-fail) followed by
# an input file. The script uses the following environment variables. The test C
# source file is expected to be named test.c in the directory containing the
# input file.
#
# CBMC: The command to run CBMC. Default: cbmc
# CBMC_FLAGS: Additional flags to pass to CBMC
# NR_CPUS: Number of cpus to run tests with. Default specified by the test
# SYNC_SRCU_MODE: Choose implementation of synchronize_srcu. Defaults to simple.
# kernel: Version included in the linux kernel source.
# simple: Use try_check_zero directly.
#
# The input file is a script that is sourced by this file. It can define any of
# the following variables to configure the test.
#
# test_cbmc_options: Extra options to pass to CBMC.
# min_cpus_fail: Minimum number of CPUs (NR_CPUS) for verification to fail.
# The test is expected to pass if it is run with fewer. (Only
# useful for .fail files)
# default_cpus: Quantity of CPUs to use for the test, if not specified on the
# command line. Default: Larger of 2 and MIN_CPUS_FAIL.
set -e
if test "$#" -ne 2; then
echo "Expected one option followed by an input file" 1>&2
exit 99
fi
if test "x$1" = "x--should-pass"; then
should_pass="yes"
elif test "x$1" = "x--should-fail"; then
should_pass="no"
else
echo "Unrecognized argument '$1'" 1>&2
# Exit code 99 indicates a hard error.
exit 99
fi
CBMC=${CBMC:-cbmc}
SYNC_SRCU_MODE=${SYNC_SRCU_MODE:-simple}
case ${SYNC_SRCU_MODE} in
kernel) sync_srcu_mode_flags="" ;;
simple) sync_srcu_mode_flags="-DUSE_SIMPLE_SYNC_SRCU" ;;
*)
echo "Unrecognized argument '${SYNC_SRCU_MODE}'" 1>&2
exit 99
;;
esac
min_cpus_fail=1
c_file=`dirname "$2"`/test.c
# Source the input file.
. $2
if test ${min_cpus_fail} -gt 2; then
default_default_cpus=${min_cpus_fail}
else
default_default_cpus=2
fi
default_cpus=${default_cpus:-${default_default_cpus}}
cpus=${NR_CPUS:-${default_cpus}}
# Check if there are two few cpus to make the test fail.
if test $cpus -lt ${min_cpus_fail:-0}; then
should_pass="yes"
fi
cbmc_opts="-DNR_CPUS=${cpus} ${sync_srcu_mode_flags} ${test_cbmc_options} ${CBMC_FLAGS}"
echo "Running CBMC: ${CBMC} ${cbmc_opts} ${c_file}"
if ${CBMC} ${cbmc_opts} "${c_file}"; then
# Verification successful. Make sure that it was supposed to verify.
test "x${should_pass}" = xyes
else
cbmc_exit_status=$?
# An exit status of 10 indicates a failed verification.
# (see cbmc_parse_optionst::do_bmc in the CBMC source code)
if test ${cbmc_exit_status} -eq 10 && test "x${should_pass}" = xno; then
:
else
echo "CBMC returned ${cbmc_exit_status} exit status" 1>&2
# Parse errors have exit status 6. Any other type of error
# should be considered a hard error.
if test ${cbmc_exit_status} -ne 6 && \
test ${cbmc_exit_status} -ne 10; then
exit 99
else
exit 1
fi
fi
fi