diff options
| author |   Soheil Hassas Yeganeh <soheil@google.com> | 2020-12-18 14:01:48 -0800 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2020-12-19 11:18:37 -0800 |
| commit | 2efdaf7660c408d57721cc6dacb0167f866cb451 (patch) | |
| tree | f408a18b19361393572b8a59525bf97826fd08f9 /fs/eventpoll.c | |
| parent | epoll: check for events when removing a timed out thread from the wait queue (diff) | |
| download | linux-dev-2efdaf7660c408d57721cc6dacb0167f866cb451.tar.xz linux-dev-2efdaf7660c408d57721cc6dacb0167f866cb451.zip | |
epoll: simplify signal handling
Check signals before locking ep->lock, and immediately return -EINTR if
there is any signal pending.
This saves a few loads, stores, and branches from the hot path and
simplifies the loop structure for follow up patches.
Link: https://lkml.kernel.org/r/20201106231635.3528496-3-soheil.kdev@gmail.com
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Khazhismel Kumykov <khazhy@google.com>
Cc: Guantao Liu <guantaol@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/eventpoll.c')
| -rw-r--r-- | fs/eventpoll.c | 20 |
1 files changed, 10 insertions, 10 deletions
diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 935c66c809ba..4f460be723d0 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -1733,7 +1733,7 @@ static inline struct timespec64 ep_set_mstimeout(long ms) static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events, int maxevents, long timeout) { - int res = 0, eavail, timed_out = 0; + int res, eavail, timed_out = 0; u64 slack = 0; wait_queue_entry_t wait; ktime_t expires, *to = NULL; @@ -1780,6 +1780,9 @@ fetch_events: ep_reset_busy_poll_napi_id(ep); do { + if (signal_pending(current)) + return -EINTR; + /* * Internally init_wait() uses autoremove_wake_function(), * thus wait entry is removed from the wait queue on each @@ -1809,15 +1812,12 @@ fetch_events: * important. */ eavail = ep_events_available(ep); - if (!eavail) { - if (signal_pending(current)) - res = -EINTR; - else - __add_wait_queue_exclusive(&ep->wq, &wait); - } + if (!eavail) + __add_wait_queue_exclusive(&ep->wq, &wait); + write_unlock_irq(&ep->lock); - if (!eavail && !res) + if (!eavail) timed_out = !schedule_hrtimeout_range(to, slack, HRTIMER_MODE_ABS); @@ -1853,14 +1853,14 @@ send_events: * finding more events available and fetching * repeatedly. */ - res = -EINTR; + return -EINTR; } /* * Try to transfer events to user space. In case we get 0 events and * there's still timeout left over, we go trying again in search of * more luck. */ - if (!res && eavail && + if (eavail && !(res = ep_send_events(ep, events, maxevents)) && !timed_out) goto fetch_events; |