kernel/mutex-debug.c

   1 /*
   2  * kernel/mutex-debug.c
   3  *
   4  * Debugging code for mutexes
   5  *
   6  * Started by Ingo Molnar:
   7  *
   8  *  Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
   9  *
  10  * lock debugging, locking tree, deadlock detection started by:
  11  *
  12  *  Copyright (C) 2004, LynuxWorks, Inc., Igor Manyilov, Bill Huey
  13  *  Released under the General Public License (GPL).
  14  */
  15 #include <linux/mutex.h>
  16 #include <linux/sched.h>
  17 #include <linux/delay.h>
  18 #include <linux/module.h>
  19 #include <linux/poison.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/kallsyms.h>
  22 #include <linux/interrupt.h>
  23
  24 #include "mutex-debug.h"
  25
  26 /*
  27  * We need a global lock when we walk through the multi-process
  28  * lock tree. Only used in the deadlock-debugging case.
  29  */
  30 DEFINE_SPINLOCK(debug_mutex_lock);
  31
  32 /*
  33  * All locks held by all tasks, in a single global list:
  34  */
  35 LIST_HEAD(debug_mutex_held_locks);
  36
  37 /*
  38  * In the debug case we carry the caller's instruction pointer into
  39  * other functions, but we dont want the function argument overhead
  40  * in the nondebug case - hence these macros:
  41  */
  42 #define __IP_DECL__             , unsigned long ip
  43 #define __IP__                  , ip
  44 #define __RET_IP__              , (unsigned long)__builtin_return_address(0)
  45
  46 /*
  47  * "mutex debugging enabled" flag. We turn it off when we detect
  48  * the first problem because we dont want to recurse back
  49  * into the tracing code when doing error printk or
  50  * executing a BUG():
  51  */
  52 int debug_mutex_on = 1;
  53
  54 /*
  55  * Must be called with lock->wait_lock held.
  56  */
  57 void debug_mutex_set_owner(struct mutex *lock,
  58                            struct thread_info *new_owner __IP_DECL__)
  59 {
  60         lock->owner = new_owner;
  61         DEBUG_LOCKS_WARN_ON(!list_empty(&lock->held_list));
  62         if (debug_mutex_on) {
  63                 list_add_tail(&lock->held_list, &debug_mutex_held_locks);
  64                 lock->acquire_ip = ip;
  65         }
  66 }
  67
  68 void debug_mutex_init_waiter(struct mutex_waiter *waiter)
  69 {
  70         memset(waiter, MUTEX_DEBUG_INIT, sizeof(*waiter));
  71         waiter->magic = waiter;
  72         INIT_LIST_HEAD(&waiter->list);
  73 }
  74
  75 void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter)
  76 {
  77         SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
  78         DEBUG_LOCKS_WARN_ON(list_empty(&lock->wait_list));
  79         DEBUG_LOCKS_WARN_ON(waiter->magic != waiter);
  80         DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
  81 }
  82
  83 void debug_mutex_free_waiter(struct mutex_waiter *waiter)
  84 {
  85         DEBUG_LOCKS_WARN_ON(!list_empty(&waiter->list));
  86         memset(waiter, MUTEX_DEBUG_FREE, sizeof(*waiter));
  87 }
  88
  89 void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
  90                             struct thread_info *ti __IP_DECL__)
  91 {
  92         SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
  93         /* Mark the current thread as blocked on the lock: */
  94         ti->task->blocked_on = waiter;
  95         waiter->lock = lock;
  96 }
  97
  98 void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
  99                          struct thread_info *ti)
 100 {
 101         DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
 102         DEBUG_LOCKS_WARN_ON(waiter->task != ti->task);
 103         DEBUG_LOCKS_WARN_ON(ti->task->blocked_on != waiter);
 104         ti->task->blocked_on = NULL;
 105
 106         list_del_init(&waiter->list);
 107         waiter->task = NULL;
 108 }
 109
 110 void debug_mutex_unlock(struct mutex *lock)
 111 {
 112         DEBUG_LOCKS_WARN_ON(lock->magic != lock);
 113         DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
 114         DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info());
 115         if (debug_mutex_on) {
 116                 DEBUG_LOCKS_WARN_ON(list_empty(&lock->held_list));
 117                 list_del_init(&lock->held_list);
 118         }
 119 }
 120
 121 void debug_mutex_init(struct mutex *lock, const char *name)
 122 {
 123         /*
 124          * Make sure we are not reinitializing a held lock:
 125          */
 126         mutex_debug_check_no_locks_freed((void *)lock, sizeof(*lock));
 127         lock->owner = NULL;
 128         INIT_LIST_HEAD(&lock->held_list);
 129         lock->name = name;
 130         lock->magic = lock;
 131 }
 132
 133 /***
 134  * mutex_destroy - mark a mutex unusable
 135  * @lock: the mutex to be destroyed
 136  *
 137  * This function marks the mutex uninitialized, and any subsequent
 138  * use of the mutex is forbidden. The mutex must not be locked when
 139  * this function is called.
 140  */
 141 void fastcall mutex_destroy(struct mutex *lock)
 142 {
 143         DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock));
 144         lock->magic = NULL;
 145 }
 146
 147 EXPORT_SYMBOL_GPL(mutex_destroy);