5.15-stable review patch. If anyone has any objections, please let me know.
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From: Xuewen Yan xuewen.yan@unisoc.com
commit 900bbaae67e980945dec74d36f8afe0de7556d5a 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 jing.xia@unisoc.com Signed-off-by: Jing Xia jing.xia@unisoc.com Signed-off-by: Xuewen Yan xuewen.yan@unisoc.com Link: https://lore.kernel.org/r/20240426080548.8203-1-xuewen.yan@unisoc.com Tested-by: Brian Geffon bgeffon@google.com Reviewed-by: Brian Geffon bgeffon@google.com Reported-by: Benoit Lize lizeb@google.com Signed-off-by: Christian Brauner brauner@kernel.org Cc: Brian Geffon bgeffon@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/eventpoll.c | 5 ++++- include/linux/wait.h | 1 + 2 files changed, 5 insertions(+), 1 deletion(-)
--- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -1230,7 +1230,10 @@ static int ep_poll_callback(wait_queue_e break; } } - wake_up(&ep->wq); + if (sync) + wake_up_sync(&ep->wq); + else + wake_up(&ep->wq); } if (waitqueue_active(&ep->poll_wait)) pwake++; --- a/include/linux/wait.h +++ b/include/linux/wait.h @@ -224,6 +224,7 @@ void __wake_up_pollfree(struct wait_queu #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)