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wait: Return number of exclusive waiters awaken

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Sbitmap code will need to know how many waiters were actually woken for
its batched wakeups implementation.  Return the number of woken
exclusive waiters from __wake_up() to facilitate that.

Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20221115224553.23594-3-krisman@suse.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Gabriel Krisman Bertazi 2022-11-15 17:45:52 -05:00 committed by Jens Axboe
parent 976570b4ec
commit ee7dc86b6d
2 changed files with 12 additions and 8 deletions
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2
include/linux/wait.h
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@ -209,7 +209,7 @@ __remove_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry *wq
list_del(&wq_entry->entry);
}
void __wake_up(struct wait_queue_head *wq_head, unsigned int mode, int nr, void *key);
int __wake_up(struct wait_queue_head *wq_head, unsigned int mode, int nr, void *key);
void __wake_up_locked_key(struct wait_queue_head *wq_head, unsigned int mode, void *key);
void __wake_up_locked_key_bookmark(struct wait_queue_head *wq_head,
unsigned int mode, void *key, wait_queue_entry_t *bookmark);

18
kernel/sched/wait.c
View file

@ -121,11 +121,12 @@ static int __wake_up_common(struct wait_queue_head *wq_head, unsigned int mode,
return nr_exclusive;
}
static void __wake_up_common_lock(struct wait_queue_head *wq_head, unsigned int mode,
static int __wake_up_common_lock(struct wait_queue_head *wq_head, unsigned int mode,
int nr_exclusive, int wake_flags, void *key)
{
unsigned long flags;
wait_queue_entry_t bookmark;
int remaining = nr_exclusive;
bookmark.flags = 0;
bookmark.private = NULL;
@ -134,10 +135,12 @@ static void __wake_up_common_lock(struct wait_queue_head *wq_head, unsigned int
do {
spin_lock_irqsave(&wq_head->lock, flags);
nr_exclusive = __wake_up_common(wq_head, mode, nr_exclusive,
remaining = __wake_up_common(wq_head, mode, remaining,
wake_flags, key, &bookmark);
spin_unlock_irqrestore(&wq_head->lock, flags);
} while (bookmark.flags & WQ_FLAG_BOOKMARK);
return nr_exclusive - remaining;
}
/**
@ -147,13 +150,14 @@ static void __wake_up_common_lock(struct wait_queue_head *wq_head, unsigned int
* @nr_exclusive: how many wake-one or wake-many threads to wake up
* @key: is directly passed to the wakeup function
*
* If this function wakes up a task, it executes a full memory barrier before
* accessing the task state.
* If this function wakes up a task, it executes a full memory barrier
* before accessing the task state. Returns the number of exclusive
* tasks that were awaken.
*/
void __wake_up(struct wait_queue_head *wq_head, unsigned int mode,
int nr_exclusive, void *key)
int __wake_up(struct wait_queue_head *wq_head, unsigned int mode,
int nr_exclusive, void *key)
{
__wake_up_common_lock(wq_head, mode, nr_exclusive, 0, key);
return __wake_up_common_lock(wq_head, mode, nr_exclusive, 0, key);
}
EXPORT_SYMBOL(__wake_up);