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Commit 81fc685a authored by Ingo Molnar's avatar Ingo Molnar Committed by Linus Torvalds
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[PATCH] lockdep: improve verbose messages 



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: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent a6640897

kernel/lockdep.c

+6 −2
Original line number Diff line number Diff line
@@ -1264,7 +1264,7 @@ 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;
@@ -1286,9 +1286,13 @@ 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:
@@ -2139,7 +2143,7 @@ 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:

		 *