Messages in this thread Patch in this message | | | Date | Thu, 7 Dec 2006 10:21:42 +0100 | From | Ingo Molnar <> | Subject | [patch] lockdep: improve verbose messages |
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Subject: [patch] lockdep: improve verbose messages From: Ingo Molnar <mingo@elte.hu>
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> --- kernel/lockdep.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
Index: linux/kernel/lockdep.c =================================================================== --- linux.orig/kernel/lockdep.c +++ linux/kernel/lockdep.c @@ -1266,7 +1266,7 @@ out_unlock_set: * 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; @@ -1288,9 +1288,13 @@ cache_hit: __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: @@ -2140,7 +2144,7 @@ out_calc_hash: * (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: * - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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