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[PATCH] lockdep: improve verbose messages

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Make verbose lockdep messages (off by default) more informative by printing
out the hash chain key.  (this patch was what helped me catch the earlier
lockdep hash-collision bug)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Ingo Molnar 2006-12-13 00:34:40 -08:00 committed by Linus Torvalds
parent a664089741
commit 81fc685a89
1 changed files with 6 additions and 2 deletions
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8
kernel/lockdep.c
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@ -1264,7 +1264,7 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
* add it and return 0 - in this case the new dependency chain is
* validated. If the key is already hashed, return 1.
*/
static inline int lookup_chain_cache(u64 chain_key)
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;
@ -1286,9 +1286,13 @@ static inline int lookup_chain_cache(u64 chain_key)
__raw_spin_lock(&hash_lock);
return 1;
#endif
if (very_verbose(class))
printk("\nhash chain already cached, key: %016Lx tail class: [%p] %s\n", chain_key, class->key, class->name);
return 0;
}
}
if (very_verbose(class))
printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n", chain_key, class->key, class->name);
/*
* Allocate a new chain entry from the static array, and add
* it to the hash:
@ -2139,7 +2143,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
* (If lookup_chain_cache() returns with 1 it acquires
* hash_lock for us)
*/
if (!trylock && (check == 2) && lookup_chain_cache(chain_key)) {
if (!trylock && (check == 2) && lookup_chain_cache(chain_key, class)) {
/*
* Check whether last held lock:
*