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workqueue: debug flushing deadlocks with lockdep

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In the following scenario:

code path 1:
  my_function() -> lock(L1); ...; flush_workqueue(); ...

code path 2:
  run_workqueue() -> my_work() -> ...; lock(L1); ...

you can get a deadlock when my_work() is queued or running
but my_function() has acquired L1 already.

This patch adds a pseudo-lock to each workqueue to make lockdep
warn about this scenario.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Johannes Berg 2007-10-18 23:39:55 -07:00 • committed by Linus Torvalds
parent cf7b708c8d
commit 4e6045f134
4 changed files with 88 additions and 7 deletions
Download patch file Download diff file Expand all files Collapse all files

49
include/linux/workqueue.h
View file

@ -8,6 +8,7 @@
#include <linux/timer.h>
#include <linux/linkage.h>
#include <linux/bitops.h>
#include <linux/lockdep.h>
#include <asm/atomic.h>
struct workqueue_struct;
@ -28,6 +29,9 @@ struct work_struct {
#define WORK_STRUCT_WQ_DATA_MASK (~WORK_STRUCT_FLAG_MASK)
struct list_head entry;
work_func_t func;
#ifdef CONFIG_LOCKDEP
struct lockdep_map lockdep_map;
#endif
};
#define WORK_DATA_INIT() ATOMIC_LONG_INIT(0)
@ -41,10 +45,23 @@ struct execute_work {
struct work_struct work;
};
#ifdef CONFIG_LOCKDEP
/*
* NB: because we have to copy the lockdep_map, setting _key
* here is required, otherwise it could get initialised to the
* copy of the lockdep_map!
*/
#define __WORK_INIT_LOCKDEP_MAP(n, k) \
.lockdep_map = STATIC_LOCKDEP_MAP_INIT(n, k),
#else
#define __WORK_INIT_LOCKDEP_MAP(n, k)
#endif
#define __WORK_INITIALIZER(n, f) { \
.data = WORK_DATA_INIT(), \
.entry = { &(n).entry, &(n).entry }, \
.func = (f), \
__WORK_INIT_LOCKDEP_MAP(#n, &(n)) \
}
#define __DELAYED_WORK_INITIALIZER(n, f) { \
@ -76,12 +93,24 @@ struct execute_work {
* assignment of the work data initializer allows the compiler
* to generate better code.
*/
#ifdef CONFIG_LOCKDEP
#define INIT_WORK(_work, _func) \
do { \
static struct lock_class_key __key; \
\
(_work)->data = (atomic_long_t) WORK_DATA_INIT(); \
lockdep_init_map(&(_work)->lockdep_map, #_work, &__key, 0);\
INIT_LIST_HEAD(&(_work)->entry); \
PREPARE_WORK((_work), (_func)); \
} while (0)
#else
#define INIT_WORK(_work, _func) \
do { \
(_work)->data = (atomic_long_t) WORK_DATA_INIT(); \
INIT_LIST_HEAD(&(_work)->entry); \
PREPARE_WORK((_work), (_func)); \
} while (0)
#endif
#define INIT_DELAYED_WORK(_work, _func) \
do { \
@ -118,9 +147,23 @@ struct execute_work {
clear_bit(WORK_STRUCT_PENDING, work_data_bits(work))
extern struct workqueue_struct *__create_workqueue(const char *name,
int singlethread,
int freezeable);
extern struct workqueue_struct *
__create_workqueue_key(const char *name, int singlethread,
int freezeable, struct lock_class_key *key);
#ifdef CONFIG_LOCKDEP
#define __create_workqueue(name, singlethread, freezeable) \
({ \
static struct lock_class_key __key; \
\
__create_workqueue_key((name), (singlethread), \
(freezeable), &__key); \
})
#else
#define __create_workqueue(name, singlethread, freezeable) \
__create_workqueue_key((name), (singlethread), (freezeable), NULL)
#endif
#define create_workqueue(name) __create_workqueue((name), 0, 0)
#define create_freezeable_workqueue(name) __create_workqueue((name), 1, 1)
#define create_singlethread_workqueue(name) __create_workqueue((name), 1, 0)