2024-04-26 08:08:26

by Xuewen Yan

[permalink] [raw]
Subject: [RFC PATCH] epoll: Add synchronous wakeup support for ep_poll_callback

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 <[email protected]>
Signed-off-by: Jing Xia <[email protected]>
Signed-off-by: Xuewen Yan <[email protected]>
---
fs/eventpoll.c | 5 ++++-
include/linux/wait.h | 1 +
2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 882b89edc52a..9b815e0a1ac5 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1336,7 +1336,10 @@ 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 8aa3372f21a0..2b322a9b88a2 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -221,6 +221,7 @@ 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)

#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)
--
2.25.1



2024-04-26 08:39:20

by Christian Brauner

[permalink] [raw]
Subject: Re: [RFC PATCH] epoll: Add synchronous wakeup support for ep_poll_callback

adding Eric

On Fri, Apr 26, 2024 at 04:05:48PM +0800, Xuewen Yan wrote:
> 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 <[email protected]>
> Signed-off-by: Jing Xia <[email protected]>
> Signed-off-by: Xuewen Yan <[email protected]>
> ---
> fs/eventpoll.c | 5 ++++-
> include/linux/wait.h | 1 +
> 2 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/fs/eventpoll.c b/fs/eventpoll.c
> index 882b89edc52a..9b815e0a1ac5 100644
> --- a/fs/eventpoll.c
> +++ b/fs/eventpoll.c
> @@ -1336,7 +1336,10 @@ 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 8aa3372f21a0..2b322a9b88a2 100644
> --- a/include/linux/wait.h
> +++ b/include/linux/wait.h
> @@ -221,6 +221,7 @@ 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)
>
> #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)
> --
> 2.25.1
>