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locking, sched: Give waitqueue spinlocks their own lockdep classes 

Give waitqueue spinlocks their own lockdep classes when they
are initialised from init_waitqueue_head().  This means that
struct wait_queue::func functions can operate other waitqueues.

This is used by CacheFiles to catch the page from a backing fs
being unlocked and to wake up another thread to take a copy of
it.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Takashi Iwai <tiwai@suse.de>
Cc: linux-cachefs@redhat.com
Cc: torvalds@osdl.org
Cc: akpm@linux-foundation.org
LKML-Reference: <20090810113305.17284.81508.stgit@warthog.procyon.org.uk>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2009-08-10 12:33:05 +01:00 committed by Ingo Molnar
parent beda2c7ea2
commit 2fc391112f
2 changed files with 11 additions and 3 deletions
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9
include/linux/wait.h
View File

@ -77,7 +77,14 @@ struct task_struct;
#define __WAIT_BIT_KEY_INITIALIZER(word, bit) \
{ .flags = word, .bit_nr = bit, }
extern void init_waitqueue_head(wait_queue_head_t *q);
extern void __init_waitqueue_head(wait_queue_head_t *q, struct lock_class_key *);
#define init_waitqueue_head(q) \
do { \
static struct lock_class_key __key; \
\
__init_waitqueue_head((q), &__key); \
} while (0)
#ifdef CONFIG_LOCKDEP
# define __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) \

5
kernel/wait.c
View File

@ -10,13 +10,14 @@
#include <linux/wait.h>
#include <linux/hash.h>
void init_waitqueue_head(wait_queue_head_t *q)
void __init_waitqueue_head(wait_queue_head_t *q, struct lock_class_key *key)
{
spin_lock_init(&q->lock);
lockdep_set_class(&q->lock, key);
INIT_LIST_HEAD(&q->task_list);
}
EXPORT_SYMBOL(init_waitqueue_head);
EXPORT_SYMBOL(__init_waitqueue_head);
void add_wait_queue(wait_queue_head_t *q, wait_queue_t *wait)
{