From eb13ba873881abd5e15af784756a61af635e665e Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Wed, 16 Jan 2008 09:51:58 +0100 Subject: [PATCH] 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 Signed-off-by: Ingo Molnar Signed-off-by: Peter Zijlstra --- include/linux/workqueue.h | 14 +++++++++++--- kernel/workqueue.c | 5 +++-- 2 files changed, 14 insertions(+), 5 deletions(-) diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index 7daafdc2514b..7f28c32d9aca 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 52d5e7c9a8e6..8db0b597509e 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); -- 2.39.5