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authorJohannes Berg <johannes@sipsolutions.net>2008-01-16 09:51:58 +0100
committerPeter Zijlstra <a.p.zijlstra@chello.nl>2008-01-16 09:51:58 +0100
commiteb13ba873881abd5e15af784756a61af635e665e (patch)
tree228bf4afa2c4418ad09cd50b3ebb762f793ed84a
parent5a26db5bd25cf4bf32ae9fa9f6136b6b6d5b45c5 (diff)
lockdep: fix workqueue creation API lockdep interaction
Dave Young reported warnings from lockdep that the workqueue API can sometimes try to register lockdep classes with the same key but different names. This is not permitted in lockdep. Unfortunately, I was unaware of that restriction when I wrote the code to debug workqueue problems with lockdep and used the workqueue name as the lockdep class name. This can obviously lead to the problem if the workqueue name is dynamic. This patch solves the problem by always using a constant name for the workqueue's lockdep class, namely either the constant name that was passed in or a string consisting of the variable name. Signed-off-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
-rw-r--r--include/linux/workqueue.h14
-rw-r--r--kernel/workqueue.c5
2 files changed, 14 insertions, 5 deletions
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 7daafdc2514..7f28c32d9ac 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -149,19 +149,27 @@ struct execute_work {
extern struct workqueue_struct *
__create_workqueue_key(const char *name, int singlethread,
- int freezeable, struct lock_class_key *key);
+ int freezeable, struct lock_class_key *key,
+ const char *lock_name);
#ifdef CONFIG_LOCKDEP
#define __create_workqueue(name, singlethread, freezeable) \
({ \
static struct lock_class_key __key; \
+ const char *__lock_name; \
+ \
+ if (__builtin_constant_p(name)) \
+ __lock_name = (name); \
+ else \
+ __lock_name = #name; \
\
__create_workqueue_key((name), (singlethread), \
- (freezeable), &__key); \
+ (freezeable), &__key, \
+ __lock_name); \
})
#else
#define __create_workqueue(name, singlethread, freezeable) \
- __create_workqueue_key((name), (singlethread), (freezeable), NULL)
+ __create_workqueue_key((name), (singlethread), (freezeable), NULL, NULL)
#endif
#define create_workqueue(name) __create_workqueue((name), 0, 0)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 52d5e7c9a8e..8db0b597509 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -722,7 +722,8 @@ static void start_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu)
struct workqueue_struct *__create_workqueue_key(const char *name,
int singlethread,
int freezeable,
- struct lock_class_key *key)
+ struct lock_class_key *key,
+ const char *lock_name)
{
struct workqueue_struct *wq;
struct cpu_workqueue_struct *cwq;
@@ -739,7 +740,7 @@ struct workqueue_struct *__create_workqueue_key(const char *name,
}
wq->name = name;
- lockdep_init_map(&wq->lockdep_map, name, key, 0);
+ lockdep_init_map(&wq->lockdep_map, lock_name, key, 0);
wq->singlethread = singlethread;
wq->freezeable = freezeable;
INIT_LIST_HEAD(&wq->list);