This is a note to let you know that I've just added the patch titled
epoll: Add synchronous wakeup support for ep_poll_callback
to the 5.4-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:
epoll-add-synchronous-wakeup-support-for-ep_poll_cal.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit f8a05f73700a36801f76c3deaede7dcf06f537c5
Author: Xuewen Yan <xuewen.yan@xxxxxxxxxx>
Date: Thu Dec 26 19:14:29 2024 +0800
epoll: Add synchronous wakeup support for ep_poll_callback
[ Upstream commit 900bbaae67e980945dec74d36f8afe0de7556d5a ]
Now, the epoll only use wake_up() interface to wake up task.
However, sometimes, there are epoll users which want to use
the synchronous wakeup flag to hint the scheduler, such as
Android binder driver.
So add a wake_up_sync() define, and use the wake_up_sync()
when the sync is true in ep_poll_callback().
Co-developed-by: Jing Xia <jing.xia@xxxxxxxxxx>
Signed-off-by: Jing Xia <jing.xia@xxxxxxxxxx>
Signed-off-by: Xuewen Yan <xuewen.yan@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240426080548.8203-1-xuewen.yan@xxxxxxxxxx
Tested-by: Brian Geffon <bgeffon@xxxxxxxxxx>
Reviewed-by: Brian Geffon <bgeffon@xxxxxxxxxx>
Reported-by: Benoit Lize <lizeb@xxxxxxxxxx>
Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
[ Redefine wake_up_sync(x) as __wake_up_sync(x, TASK_NORMAL, 1) to
make it work on 5.4.y ]
Signed-off-by: Wenshan Lan <jetlan9@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 8c0e94183186..569bfff280e4 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1273,7 +1273,10 @@ static int ep_poll_callback(wait_queue_entry_t *wait, unsigned mode, int sync, v
break;
}
}
- wake_up(&ep->wq);
+ if (sync)
+ wake_up_sync(&ep->wq);
+ else
+ wake_up(&ep->wq);
}
if (waitqueue_active(&ep->poll_wait))
pwake++;
diff --git a/include/linux/wait.h b/include/linux/wait.h
index 03bff85e365f..5b65f720261a 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -213,6 +213,7 @@ void __wake_up_pollfree(struct wait_queue_head *wq_head);
#define wake_up_all(x) __wake_up(x, TASK_NORMAL, 0, NULL)
#define wake_up_locked(x) __wake_up_locked((x), TASK_NORMAL, 1)
#define wake_up_all_locked(x) __wake_up_locked((x), TASK_NORMAL, 0)
+#define wake_up_sync(x) __wake_up_sync(x, TASK_NORMAL, 1)
#define wake_up_interruptible(x) __wake_up(x, TASK_INTERRUPTIBLE, 1, NULL)
#define wake_up_interruptible_nr(x, nr) __wake_up(x, TASK_INTERRUPTIBLE, nr, NULL)
