diff options
| author | Jarek Poplawski <jarkao2@o2.pl> | 2007-02-10 12:44:58 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-02-11 21:51:26 +0300 |
| commit | 381a229209aa6f7f72375797b7bcfcfe2ae6fcbb (patch) | |
| tree | bbd92afe1437ac77084c6ba3485f7f5a988dd673 /kernel/lockdep.c | |
| parent | 898552c9d807fe59f3ecaf9c300c109358375c12 (diff) | |
| download | linux-381a229209aa6f7f72375797b7bcfcfe2ae6fcbb.tar.xz | |
[PATCH] lockdep: more unlock-on-error fixes
- returns after DEBUG_LOCKS_WARN_ON added in 3 places
- debug_locks checking after lookup_chain_cache() added in
__lock_acquire()
- locking for testing and changing global variable max_lockdep_depth
added in __lock_acquire()
From: Ingo Molnar <mingo@elte.hu>
My __acquire_lock() cleanup introduced a locking bug: on SMP systems we'd
release a non-owned graph lock. Fix this by moving the graph unlock back,
and by leaving the max_lockdep_depth variable update possibly racy. (we
dont care, it's just statistics)
Also add some minimal debugging code to graph_unlock()/graph_lock(),
which caught this locking bug.
Signed-off-by: Jarek Poplawski <jarkao2@o2.pl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/lockdep.c')
| -rw-r--r-- | kernel/lockdep.c | 23 |
1 files changed, 19 insertions, 4 deletions
diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 509efd49540f..2d616f4d853c 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -70,6 +70,9 @@ static int graph_lock(void) static inline int graph_unlock(void) { + if (debug_locks && !__raw_spin_is_locked(&lockdep_lock)) + return DEBUG_LOCKS_WARN_ON(1); + __raw_spin_unlock(&lockdep_lock); return 0; } @@ -712,6 +715,9 @@ find_usage_backwards(struct lock_class *source, unsigned int depth) struct lock_list *entry; int ret; + if (!__raw_spin_is_locked(&lockdep_lock)) + return DEBUG_LOCKS_WARN_ON(1); + if (depth > max_recursion_depth) max_recursion_depth = depth; if (depth >= RECURSION_LIMIT) @@ -1293,7 +1299,8 @@ out_unlock_set: if (!subclass || force) lock->class_cache = class; - DEBUG_LOCKS_WARN_ON(class->subclass != subclass); + if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass)) + return NULL; return class; } @@ -1308,7 +1315,8 @@ static inline int lookup_chain_cache(u64 chain_key, struct lock_class *class) struct list_head *hash_head = chainhashentry(chain_key); struct lock_chain *chain; - DEBUG_LOCKS_WARN_ON(!irqs_disabled()); + if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) + return 0; /* * We can walk it lock-free, because entries only get added * to the hash: @@ -1394,7 +1402,9 @@ static void check_chain_key(struct task_struct *curr) return; } id = hlock->class - lock_classes; - DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS); + if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS)) + return; + if (prev_hlock && (prev_hlock->irq_context != hlock->irq_context)) chain_key = 0; @@ -2205,7 +2215,11 @@ out_calc_hash: if (!check_prevs_add(curr, hlock)) return 0; graph_unlock(); - } + } else + /* after lookup_chain_cache(): */ + if (unlikely(!debug_locks)) + return 0; + curr->lockdep_depth++; check_chain_key(curr); if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) { @@ -2214,6 +2228,7 @@ out_calc_hash: printk("turning off the locking correctness validator.\n"); return 0; } + if (unlikely(curr->lockdep_depth > max_lockdep_depth)) max_lockdep_depth = curr->lockdep_depth; |