fs/epoll: deal with wait_queue only once (86c05179) · Commits · 戴 / test

fs/eventpoll.c

+18 −11

Original line number	Diff line number	Diff line
		@@ -1749,6 +1749,7 @@ static int ep_poll(struct eventpoll ep, struct epoll_event __user events,
		{
		int res = 0, eavail, timed_out = 0;
		u64 slack = 0;
		bool waiter = false;
		wait_queue_entry_t wait;
		ktime_t expires, *to = NULL;

		@@ -1794,14 +1795,18 @@ fetch_events:
		ep_reset_busy_poll_napi_id(ep);

		/*
		* We don't have any available event to return to the caller.
		* We need to sleep here, and we will be wake up by
		* ep_poll_callback() when events will become available.
		* We don't have any available event to return to the caller. We need
		* to sleep here, and we will be woken by ep_poll_callback() when events
		* become available.
		*/
		if (!waiter) {
		waiter = true;
		init_waitqueue_entry(&wait, current);

		spin_lock_irq(&ep->wq.lock);
		__add_wait_queue_exclusive(&ep->wq, &wait);
		spin_unlock_irq(&ep->wq.lock);
		}

		for (;;) {
		/*
		@@ -1837,10 +1842,6 @@ fetch_events:

		__set_current_state(TASK_RUNNING);

		spin_lock_irq(&ep->wq.lock);
		__remove_wait_queue(&ep->wq, &wait);
		spin_unlock_irq(&ep->wq.lock);

		send_events:
		/*
		* Try to transfer events to user space. In case we get 0 events and
		@@ -1851,6 +1852,12 @@ send_events:
		!(res = ep_send_events(ep, events, maxevents)) && !timed_out)
		goto fetch_events;

		if (waiter) {
		spin_lock_irq(&ep->wq.lock);
		__remove_wait_queue(&ep->wq, &wait);
		spin_unlock_irq(&ep->wq.lock);
		}

		return res;
		}