This is a note to let you know that I've just added the patch titled
wait: Return number of exclusive waiters awaken
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
wait-return-number-of-exclusive-waiters-awaken.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From ee7dc86b6d3e3b86c2c487f713eda657850de238 Mon Sep 17 00:00:00 2001
From: Gabriel Krisman Bertazi <krisman@xxxxxxx>
Date: Tue, 15 Nov 2022 17:45:52 -0500
Subject: wait: Return number of exclusive waiters awaken
From: Gabriel Krisman Bertazi <krisman@xxxxxxx>
commit ee7dc86b6d3e3b86c2c487f713eda657850de238 upstream.
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@xxxxxxx>
Signed-off-by: Gabriel Krisman Bertazi <krisman@xxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Link: https://lore.kernel.org/r/20221115224553.23594-3-krisman@xxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/linux/wait.h | 2 +-
kernel/sched/wait.c | 18 +++++++++++-------
2 files changed, 12 insertions(+), 8 deletions(-)
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -209,7 +209,7 @@ __remove_wait_queue(struct wait_queue_he
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);
--- a/kernel/sched/wait.c
+++ b/kernel/sched/wait.c
@@ -121,11 +121,12 @@ static int __wake_up_common(struct wait_
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
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
* @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);
Patches currently in stable-queue which might be from krisman@xxxxxxx are
queue-6.1/sbitmap-use-single-per-bitmap-counting-to-wake-up-qu.patch
queue-6.1/sbitmap-advance-the-queue-index-before-waking-up-a-queue.patch
queue-6.1/sbitmap-try-each-queue-to-wake-up-at-least-one-waiter.patch
queue-6.1/wait-return-number-of-exclusive-waiters-awaken.patch
