epoll: Add synchronous wakeup support for ep_poll_callback

commit 900bbaa upstream. 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]> Cc: Brian Geffon <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
frank-w · Dec 27, 2024 · d9831a6 · d9831a6
1 parent b3ab125
commit d9831a6
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Showing 2 changed files with 5 additions and 1 deletion.
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
@@ -1268,7 +1268,10 @@ 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
@@ -225,6 +225,7 @@ 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)