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]>
Link: https://lore.kernel.org/r/[email protected]
Tested-by: Brian Geffon <[email protected]>
Reviewed-by: Brian Geffon <[email protected]>
Reported-by: Benoit Lize <[email protected]>
Signed-off-by: Christian Brauner <[email protected]>
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 90fbab6..1a06e46 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1373,7 +1373,10 @@ 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++;
