diff options
| author | Ingo Molnar <mingo@elte.hu> | 2006-12-06 20:40:50 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.osdl.org> | 2006-12-07 08:39:46 -0800 |
| commit | 70e4506765602cca047cfa31933836e354c61a63 (patch) | |
| tree | b490e5066404eab1ec7cf5147521c0bd53226b07 | |
| parent | 72be2ccfff0e0e332b32f7ef8372890e39b7c4cb (diff) | |
[PATCH] lockdep: register_lock_class() fix
The hash_lock must only ever be taken with irqs disabled. This happens in
all the important places, except one codepath: register_lock_class(). The
race should trigger rarely because register_lock_class() is quite rare and
single-threaded (happens during init most of the time).
The fix is to disable irqs.
( bug found live in -rt: there preemption is alot more agressive and
preempting with the hash-lock held caused a lockup.)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
| -rw-r--r-- | kernel/lockdep.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 3926c367435..62e73ce6819 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -1182,6 +1182,7 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) struct lockdep_subclass_key *key; struct list_head *hash_head; struct lock_class *class; + unsigned long flags; class = look_up_lock_class(lock, subclass); if (likely(class)) @@ -1203,6 +1204,7 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) key = lock->key->subkeys + subclass; hash_head = classhashentry(key); + raw_local_irq_save(flags); __raw_spin_lock(&hash_lock); /* * We have to do the hash-walk again, to avoid races @@ -1217,6 +1219,7 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) */ if (nr_lock_classes >= MAX_LOCKDEP_KEYS) { __raw_spin_unlock(&hash_lock); + raw_local_irq_restore(flags); debug_locks_off(); printk("BUG: MAX_LOCKDEP_KEYS too low!\n"); printk("turning off the locking correctness validator.\n"); @@ -1239,15 +1242,18 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) if (verbose(class)) { __raw_spin_unlock(&hash_lock); + raw_local_irq_restore(flags); printk("\nnew class %p: %s", class->key, class->name); if (class->name_version > 1) printk("#%d", class->name_version); printk("\n"); dump_stack(); + raw_local_irq_save(flags); __raw_spin_lock(&hash_lock); } out_unlock_set: __raw_spin_unlock(&hash_lock); + raw_local_irq_restore(flags); if (!subclass || force) lock->class_cache = class; |