On Sun, Nov 1, 2020 at 5:08 PM Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> After abc610e01c66 ("fs/epoll: avoid barrier after an epoll_wait(2)
> timeout"), we break out of the ep_poll loop upon timeout, without checking
> whether there is any new events available. Prior to that patch-series we
> always called ep_events_available() after exiting the loop.
This patch looks overly complicated to me.
It does the exact same thing as the "break" does, except:
- it does it the non-optimized way without the "avoid spinlock"
- it sets eavail if there was
It would seem like the *much* simpler patch is to just do this oneliner instead:
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 4df61129566d..29fa770ce1e3 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1907,6 +1907,7 @@ static int ep_poll(struct eventpoll *ep,
struct epoll_event __user *events,
if (!schedule_hrtimeout_range(to, slack, HRTIMER_MODE_ABS)) {
timed_out = 1;
+ eavail = 1;
break;
}
and *boom* you're done. That will mean that after a timeout we'll try
one more time to just do that ep_events_available() thing.
I can see no downside to just setting eavail unconditionally and
keeping the code much simpler. Hmm?
Linus
