444 lines
13 KiB
C
444 lines
13 KiB
C
#define _GNU_SOURCE
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#include <pthread.h>
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#include <stdio.h>
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#include <dlfcn.h>
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#include <stdlib.h>
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#include <sysexits.h>
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#include "include/liblockdep/mutex.h"
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#include "../../include/linux/rbtree.h"
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/**
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* struct lock_lookup - liblockdep's view of a single unique lock
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* @orig: pointer to the original pthread lock, used for lookups
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* @dep_map: lockdep's dep_map structure
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* @key: lockdep's key structure
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* @node: rb-tree node used to store the lock in a global tree
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* @name: a unique name for the lock
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*/
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struct lock_lookup {
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void *orig; /* Original pthread lock, used for lookups */
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struct lockdep_map dep_map; /* Since all locks are dynamic, we need
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* a dep_map and a key for each lock */
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/*
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* Wait, there's no support for key classes? Yup :(
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* Most big projects wrap the pthread api with their own calls to
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* be compatible with different locking methods. This means that
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* "classes" will be brokes since the function that creates all
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* locks will point to a generic locking function instead of the
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* actual code that wants to do the locking.
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*/
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struct lock_class_key key;
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struct rb_node node;
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#define LIBLOCKDEP_MAX_LOCK_NAME 22
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char name[LIBLOCKDEP_MAX_LOCK_NAME];
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};
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/* This is where we store our locks */
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static struct rb_root locks = RB_ROOT;
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static pthread_rwlock_t locks_rwlock = PTHREAD_RWLOCK_INITIALIZER;
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/* pthread mutex API */
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#ifdef __GLIBC__
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extern int __pthread_mutex_init(pthread_mutex_t *mutex, const pthread_mutexattr_t *attr);
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extern int __pthread_mutex_lock(pthread_mutex_t *mutex);
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extern int __pthread_mutex_trylock(pthread_mutex_t *mutex);
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extern int __pthread_mutex_unlock(pthread_mutex_t *mutex);
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extern int __pthread_mutex_destroy(pthread_mutex_t *mutex);
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#else
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#define __pthread_mutex_init NULL
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#define __pthread_mutex_lock NULL
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#define __pthread_mutex_trylock NULL
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#define __pthread_mutex_unlock NULL
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#define __pthread_mutex_destroy NULL
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#endif
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static int (*ll_pthread_mutex_init)(pthread_mutex_t *mutex,
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const pthread_mutexattr_t *attr) = __pthread_mutex_init;
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static int (*ll_pthread_mutex_lock)(pthread_mutex_t *mutex) = __pthread_mutex_lock;
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static int (*ll_pthread_mutex_trylock)(pthread_mutex_t *mutex) = __pthread_mutex_trylock;
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static int (*ll_pthread_mutex_unlock)(pthread_mutex_t *mutex) = __pthread_mutex_unlock;
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static int (*ll_pthread_mutex_destroy)(pthread_mutex_t *mutex) = __pthread_mutex_destroy;
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/* pthread rwlock API */
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#ifdef __GLIBC__
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extern int __pthread_rwlock_init(pthread_rwlock_t *rwlock, const pthread_rwlockattr_t *attr);
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extern int __pthread_rwlock_destroy(pthread_rwlock_t *rwlock);
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extern int __pthread_rwlock_wrlock(pthread_rwlock_t *rwlock);
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extern int __pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock);
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extern int __pthread_rwlock_rdlock(pthread_rwlock_t *rwlock);
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extern int __pthread_rwlock_tryrdlock(pthread_rwlock_t *rwlock);
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extern int __pthread_rwlock_unlock(pthread_rwlock_t *rwlock);
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#else
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#define __pthread_rwlock_init NULL
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#define __pthread_rwlock_destroy NULL
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#define __pthread_rwlock_wrlock NULL
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#define __pthread_rwlock_trywrlock NULL
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#define __pthread_rwlock_rdlock NULL
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#define __pthread_rwlock_tryrdlock NULL
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#define __pthread_rwlock_unlock NULL
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#endif
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static int (*ll_pthread_rwlock_init)(pthread_rwlock_t *rwlock,
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const pthread_rwlockattr_t *attr) = __pthread_rwlock_init;
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static int (*ll_pthread_rwlock_destroy)(pthread_rwlock_t *rwlock) = __pthread_rwlock_destroy;
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static int (*ll_pthread_rwlock_rdlock)(pthread_rwlock_t *rwlock) = __pthread_rwlock_rdlock;
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static int (*ll_pthread_rwlock_tryrdlock)(pthread_rwlock_t *rwlock) = __pthread_rwlock_tryrdlock;
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static int (*ll_pthread_rwlock_trywrlock)(pthread_rwlock_t *rwlock) = __pthread_rwlock_trywrlock;
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static int (*ll_pthread_rwlock_wrlock)(pthread_rwlock_t *rwlock) = __pthread_rwlock_wrlock;
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static int (*ll_pthread_rwlock_unlock)(pthread_rwlock_t *rwlock) = __pthread_rwlock_unlock;
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enum { none, prepare, done, } __init_state;
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static void init_preload(void);
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static void try_init_preload(void)
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{
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if (__init_state != done)
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init_preload();
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}
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static struct rb_node **__get_lock_node(void *lock, struct rb_node **parent)
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{
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struct rb_node **node = &locks.rb_node;
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struct lock_lookup *l;
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*parent = NULL;
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while (*node) {
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l = rb_entry(*node, struct lock_lookup, node);
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*parent = *node;
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if (lock < l->orig)
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node = &l->node.rb_left;
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else if (lock > l->orig)
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node = &l->node.rb_right;
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else
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return node;
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}
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return node;
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}
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#ifndef LIBLOCKDEP_STATIC_ENTRIES
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#define LIBLOCKDEP_STATIC_ENTRIES 1024
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#endif
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#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
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static struct lock_lookup __locks[LIBLOCKDEP_STATIC_ENTRIES];
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static int __locks_nr;
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static inline bool is_static_lock(struct lock_lookup *lock)
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{
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return lock >= __locks && lock < __locks + ARRAY_SIZE(__locks);
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}
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static struct lock_lookup *alloc_lock(void)
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{
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if (__init_state != done) {
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/*
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* Some programs attempt to initialize and use locks in their
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* allocation path. This means that a call to malloc() would
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* result in locks being initialized and locked.
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*
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* Why is it an issue for us? dlsym() below will try allocating
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* to give us the original function. Since this allocation will
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* result in a locking operations, we have to let pthread deal
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* with it, but we can't! we don't have the pointer to the
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* original API since we're inside dlsym() trying to get it
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*/
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int idx = __locks_nr++;
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if (idx >= ARRAY_SIZE(__locks)) {
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fprintf(stderr,
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"LOCKDEP error: insufficient LIBLOCKDEP_STATIC_ENTRIES\n");
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exit(EX_UNAVAILABLE);
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}
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return __locks + idx;
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}
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return malloc(sizeof(struct lock_lookup));
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}
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static inline void free_lock(struct lock_lookup *lock)
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{
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if (likely(!is_static_lock(lock)))
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free(lock);
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}
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/**
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* __get_lock - find or create a lock instance
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* @lock: pointer to a pthread lock function
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*
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* Try to find an existing lock in the rbtree using the provided pointer. If
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* one wasn't found - create it.
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*/
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static struct lock_lookup *__get_lock(void *lock)
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{
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struct rb_node **node, *parent;
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struct lock_lookup *l;
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ll_pthread_rwlock_rdlock(&locks_rwlock);
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node = __get_lock_node(lock, &parent);
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ll_pthread_rwlock_unlock(&locks_rwlock);
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if (*node) {
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return rb_entry(*node, struct lock_lookup, node);
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}
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/* We didn't find the lock, let's create it */
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l = alloc_lock();
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if (l == NULL)
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return NULL;
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l->orig = lock;
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/*
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* Currently the name of the lock is the ptr value of the pthread lock,
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* while not optimal, it makes debugging a bit easier.
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*
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* TODO: Get the real name of the lock using libdwarf
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*/
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sprintf(l->name, "%p", lock);
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lockdep_init_map(&l->dep_map, l->name, &l->key, 0);
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ll_pthread_rwlock_wrlock(&locks_rwlock);
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/* This might have changed since the last time we fetched it */
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node = __get_lock_node(lock, &parent);
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rb_link_node(&l->node, parent, node);
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rb_insert_color(&l->node, &locks);
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ll_pthread_rwlock_unlock(&locks_rwlock);
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return l;
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}
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static void __del_lock(struct lock_lookup *lock)
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{
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ll_pthread_rwlock_wrlock(&locks_rwlock);
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rb_erase(&lock->node, &locks);
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ll_pthread_rwlock_unlock(&locks_rwlock);
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free_lock(lock);
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}
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int pthread_mutex_init(pthread_mutex_t *mutex,
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const pthread_mutexattr_t *attr)
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{
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int r;
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/*
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* We keep trying to init our preload module because there might be
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* code in init sections that tries to touch locks before we are
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* initialized, in that case we'll need to manually call preload
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* to get us going.
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*
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* Funny enough, kernel's lockdep had the same issue, and used
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* (almost) the same solution. See look_up_lock_class() in
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* kernel/locking/lockdep.c for details.
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*/
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try_init_preload();
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r = ll_pthread_mutex_init(mutex, attr);
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if (r == 0)
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/*
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* We do a dummy initialization here so that lockdep could
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* warn us if something fishy is going on - such as
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* initializing a held lock.
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*/
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__get_lock(mutex);
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return r;
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}
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int pthread_mutex_lock(pthread_mutex_t *mutex)
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{
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int r;
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try_init_preload();
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lock_acquire(&__get_lock(mutex)->dep_map, 0, 0, 0, 1, NULL,
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(unsigned long)_RET_IP_);
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/*
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* Here's the thing with pthread mutexes: unlike the kernel variant,
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* they can fail.
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*
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* This means that the behaviour here is a bit different from what's
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* going on in the kernel: there we just tell lockdep that we took the
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* lock before actually taking it, but here we must deal with the case
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* that locking failed.
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*
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* To do that we'll "release" the lock if locking failed - this way
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* we'll get lockdep doing the correct checks when we try to take
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* the lock, and if that fails - we'll be back to the correct
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* state by releasing it.
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*/
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r = ll_pthread_mutex_lock(mutex);
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if (r)
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lock_release(&__get_lock(mutex)->dep_map, 0, (unsigned long)_RET_IP_);
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return r;
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}
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int pthread_mutex_trylock(pthread_mutex_t *mutex)
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{
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int r;
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try_init_preload();
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lock_acquire(&__get_lock(mutex)->dep_map, 0, 1, 0, 1, NULL, (unsigned long)_RET_IP_);
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r = ll_pthread_mutex_trylock(mutex);
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if (r)
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lock_release(&__get_lock(mutex)->dep_map, 0, (unsigned long)_RET_IP_);
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return r;
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}
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int pthread_mutex_unlock(pthread_mutex_t *mutex)
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{
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int r;
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try_init_preload();
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lock_release(&__get_lock(mutex)->dep_map, 0, (unsigned long)_RET_IP_);
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/*
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* Just like taking a lock, only in reverse!
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*
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* If we fail releasing the lock, tell lockdep we're holding it again.
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*/
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r = ll_pthread_mutex_unlock(mutex);
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if (r)
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lock_acquire(&__get_lock(mutex)->dep_map, 0, 0, 0, 1, NULL, (unsigned long)_RET_IP_);
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return r;
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}
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int pthread_mutex_destroy(pthread_mutex_t *mutex)
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{
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try_init_preload();
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/*
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* Let's see if we're releasing a lock that's held.
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*
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* TODO: Hook into free() and add that check there as well.
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*/
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debug_check_no_locks_freed(mutex, sizeof(*mutex));
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__del_lock(__get_lock(mutex));
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return ll_pthread_mutex_destroy(mutex);
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}
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/* This is the rwlock part, very similar to what happened with mutex above */
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int pthread_rwlock_init(pthread_rwlock_t *rwlock,
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const pthread_rwlockattr_t *attr)
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{
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int r;
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try_init_preload();
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r = ll_pthread_rwlock_init(rwlock, attr);
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if (r == 0)
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__get_lock(rwlock);
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return r;
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}
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int pthread_rwlock_destroy(pthread_rwlock_t *rwlock)
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{
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try_init_preload();
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debug_check_no_locks_freed(rwlock, sizeof(*rwlock));
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__del_lock(__get_lock(rwlock));
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return ll_pthread_rwlock_destroy(rwlock);
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}
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int pthread_rwlock_rdlock(pthread_rwlock_t *rwlock)
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{
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int r;
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init_preload();
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lock_acquire(&__get_lock(rwlock)->dep_map, 0, 0, 2, 1, NULL, (unsigned long)_RET_IP_);
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r = ll_pthread_rwlock_rdlock(rwlock);
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if (r)
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lock_release(&__get_lock(rwlock)->dep_map, 0, (unsigned long)_RET_IP_);
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return r;
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}
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int pthread_rwlock_tryrdlock(pthread_rwlock_t *rwlock)
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{
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int r;
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init_preload();
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lock_acquire(&__get_lock(rwlock)->dep_map, 0, 1, 2, 1, NULL, (unsigned long)_RET_IP_);
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r = ll_pthread_rwlock_tryrdlock(rwlock);
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if (r)
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lock_release(&__get_lock(rwlock)->dep_map, 0, (unsigned long)_RET_IP_);
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return r;
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}
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int pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock)
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{
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int r;
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init_preload();
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lock_acquire(&__get_lock(rwlock)->dep_map, 0, 1, 0, 1, NULL, (unsigned long)_RET_IP_);
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r = ll_pthread_rwlock_trywrlock(rwlock);
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if (r)
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lock_release(&__get_lock(rwlock)->dep_map, 0, (unsigned long)_RET_IP_);
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return r;
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}
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int pthread_rwlock_wrlock(pthread_rwlock_t *rwlock)
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{
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int r;
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init_preload();
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lock_acquire(&__get_lock(rwlock)->dep_map, 0, 0, 0, 1, NULL, (unsigned long)_RET_IP_);
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r = ll_pthread_rwlock_wrlock(rwlock);
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if (r)
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lock_release(&__get_lock(rwlock)->dep_map, 0, (unsigned long)_RET_IP_);
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return r;
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}
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int pthread_rwlock_unlock(pthread_rwlock_t *rwlock)
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{
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int r;
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init_preload();
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lock_release(&__get_lock(rwlock)->dep_map, 0, (unsigned long)_RET_IP_);
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r = ll_pthread_rwlock_unlock(rwlock);
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if (r)
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lock_acquire(&__get_lock(rwlock)->dep_map, 0, 0, 0, 1, NULL, (unsigned long)_RET_IP_);
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return r;
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}
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__attribute__((constructor)) static void init_preload(void)
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{
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if (__init_state == done)
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return;
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#ifndef __GLIBC__
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__init_state = prepare;
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ll_pthread_mutex_init = dlsym(RTLD_NEXT, "pthread_mutex_init");
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ll_pthread_mutex_lock = dlsym(RTLD_NEXT, "pthread_mutex_lock");
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ll_pthread_mutex_trylock = dlsym(RTLD_NEXT, "pthread_mutex_trylock");
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ll_pthread_mutex_unlock = dlsym(RTLD_NEXT, "pthread_mutex_unlock");
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ll_pthread_mutex_destroy = dlsym(RTLD_NEXT, "pthread_mutex_destroy");
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ll_pthread_rwlock_init = dlsym(RTLD_NEXT, "pthread_rwlock_init");
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ll_pthread_rwlock_destroy = dlsym(RTLD_NEXT, "pthread_rwlock_destroy");
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ll_pthread_rwlock_rdlock = dlsym(RTLD_NEXT, "pthread_rwlock_rdlock");
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ll_pthread_rwlock_tryrdlock = dlsym(RTLD_NEXT, "pthread_rwlock_tryrdlock");
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ll_pthread_rwlock_wrlock = dlsym(RTLD_NEXT, "pthread_rwlock_wrlock");
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ll_pthread_rwlock_trywrlock = dlsym(RTLD_NEXT, "pthread_rwlock_trywrlock");
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ll_pthread_rwlock_unlock = dlsym(RTLD_NEXT, "pthread_rwlock_unlock");
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#endif
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__init_state = done;
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}
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