diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index a6d5e5e4d084a800d2e4a739d8443f5b63445d9f..47d42eff6124670ee19813f3cfc64d22d67bc4f8 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -213,10 +213,12 @@ struct held_lock {
* interrupt context:
*/
unsigned int irq_context:2; /* bit 0 - soft, bit 1 - hard */
- unsigned int trylock:1;
+ unsigned int trylock:1; /* 16 bits */
+
unsigned int read:2; /* see lock_acquire() comment */
unsigned int check:2; /* see lock_acquire() comment */
unsigned int hardirqs_off:1;
+ unsigned int references:11; /* 32 bits */
};
/*
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 28914a5099142a596d6838e9ab8c9504a98f361e..0bb246e21cd792eb88ac3fc45495bbde654ca01b 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -2708,13 +2708,15 @@ EXPORT_SYMBOL_GPL(lockdep_init_map);
*/
static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
int trylock, int read, int check, int hardirqs_off,
- struct lockdep_map *nest_lock, unsigned long ip)
+ struct lockdep_map *nest_lock, unsigned long ip,
+ int references)
{
struct task_struct *curr = current;
struct lock_class *class = NULL;
struct held_lock *hlock;
unsigned int depth, id;
int chain_head = 0;
+ int class_idx;
u64 chain_key;
if (!prove_locking)
@@ -2762,10 +2764,24 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
return 0;
+ class_idx = class - lock_classes + 1;
+
+ if (depth) {
+ hlock = curr->held_locks + depth - 1;
+ if (hlock->class_idx == class_idx && nest_lock) {
+ if (hlock->references)
+ hlock->references++;
+ else
+ hlock->references = 2;
+
+ return 1;
+ }
+ }
+
hlock = curr->held_locks + depth;
if (DEBUG_LOCKS_WARN_ON(!class))
return 0;
- hlock->class_idx = class - lock_classes + 1;
+ hlock->class_idx = class_idx;
hlock->acquire_ip = ip;
hlock->instance = lock;
hlock->nest_lock = nest_lock;
@@ -2773,6 +2789,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
hlock->read = read;
hlock->check = check;
hlock->hardirqs_off = !!hardirqs_off;
+ hlock->references = references;
#ifdef CONFIG_LOCK_STAT
hlock->waittime_stamp = 0;
hlock->holdtime_stamp = sched_clock();
@@ -2881,6 +2898,30 @@ static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
return 1;
}
+static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
+{
+ if (hlock->instance == lock)
+ return 1;
+
+ if (hlock->references) {
+ struct lock_class *class = lock->class_cache;
+
+ if (!class)
+ class = look_up_lock_class(lock, 0);
+
+ if (DEBUG_LOCKS_WARN_ON(!class))
+ return 0;
+
+ if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
+ return 0;
+
+ if (hlock->class_idx == class - lock_classes + 1)
+ return 1;
+ }
+
+ return 0;
+}
+
static int
__lock_set_class(struct lockdep_map *lock, const char *name,
struct lock_class_key *key, unsigned int subclass,
@@ -2904,7 +2945,7 @@ __lock_set_class(struct lockdep_map *lock, const char *name,
*/
if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
break;
- if (hlock->instance == lock)
+ if (match_held_lock(hlock, lock))
goto found_it;
prev_hlock = hlock;
}
@@ -2923,7 +2964,8 @@ found_it:
if (!__lock_acquire(hlock->instance,
hlock_class(hlock)->subclass, hlock->trylock,
hlock->read, hlock->check, hlock->hardirqs_off,
- hlock->nest_lock, hlock->acquire_ip))
+ hlock->nest_lock, hlock->acquire_ip,
+ hlock->references))
return 0;
}
@@ -2962,20 +3004,34 @@ lock_release_non_nested(struct task_struct *curr,
*/
if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
break;
- if (hlock->instance == lock)
+ if (match_held_lock(hlock, lock))
goto found_it;
prev_hlock = hlock;
}
return print_unlock_inbalance_bug(curr, lock, ip);
found_it:
- lock_release_holdtime(hlock);
+ if (hlock->instance == lock)
+ lock_release_holdtime(hlock);
+
+ if (hlock->references) {
+ hlock->references--;
+ if (hlock->references) {
+ /*
+ * We had, and after removing one, still have
+ * references, the current lock stack is still
+ * valid. We're done!
+ */
+ return 1;
+ }
+ }
/*
* We have the right lock to unlock, 'hlock' points to it.
* Now we remove it from the stack, and add back the other
* entries (if any), recalculating the hash along the way:
*/
+
curr->lockdep_depth = i;
curr->curr_chain_key = hlock->prev_chain_key;
@@ -2984,7 +3040,8 @@ found_it:
if (!__lock_acquire(hlock->instance,
hlock_class(hlock)->subclass, hlock->trylock,
hlock->read, hlock->check, hlock->hardirqs_off,
- hlock->nest_lock, hlock->acquire_ip))
+ hlock->nest_lock, hlock->acquire_ip,
+ hlock->references))
return 0;
}
@@ -3014,7 +3071,7 @@ static int lock_release_nested(struct task_struct *curr,
/*
* Is the unlock non-nested:
*/
- if (hlock->instance != lock)
+ if (hlock->instance != lock || hlock->references)
return lock_release_non_nested(curr, lock, ip);
curr->lockdep_depth--;
@@ -3065,7 +3122,9 @@ static int __lock_is_held(struct lockdep_map *lock)
int i;
for (i = 0; i < curr->lockdep_depth; i++) {
- if (curr->held_locks[i].instance == lock)
+ struct held_lock *hlock = curr->held_locks + i;
+
+ if (match_held_lock(hlock, lock))
return 1;
}
@@ -3148,7 +3207,7 @@ void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
current->lockdep_recursion = 1;
__lock_acquire(lock, subclass, trylock, read, check,
- irqs_disabled_flags(flags), nest_lock, ip);
+ irqs_disabled_flags(flags), nest_lock, ip, 0);
current->lockdep_recursion = 0;
raw_local_irq_restore(flags);
}
@@ -3252,7 +3311,7 @@ __lock_contended(struct lockdep_map *lock, unsigned long ip)
*/
if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
break;
- if (hlock->instance == lock)
+ if (match_held_lock(hlock, lock))
goto found_it;
prev_hlock = hlock;
}
@@ -3260,6 +3319,9 @@ __lock_contended(struct lockdep_map *lock, unsigned long ip)
return;
found_it:
+ if (hlock->instance != lock)
+ return;
+
hlock->waittime_stamp = sched_clock();
contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
@@ -3299,7 +3361,7 @@ __lock_acquired(struct lockdep_map *lock, unsigned long ip)
*/
if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
break;
- if (hlock->instance == lock)
+ if (match_held_lock(hlock, lock))
goto found_it;
prev_hlock = hlock;
}
@@ -3307,6 +3369,9 @@ __lock_acquired(struct lockdep_map *lock, unsigned long ip)
return;
found_it:
+ if (hlock->instance != lock)
+ return;
+
cpu = smp_processor_id();
if (hlock->waittime_stamp) {
now = sched_clock();