event-loop: make signalfd non-blocking

When we add more that one source to a signal, then wayland will
block in wl_event_loop_dispatch. This is due to the attampt to read
from signal's fd each time the source is dispatched.

  wl_event_loop_add_signal(loop, SIGINT, ...);
  wl_event_loop_add_signal(loop, SIGINT, ...);

  /* raise signal .. */

  /* we got two fd's ready, both for the one SIGINT */
  epoll_wait(...) = 2

  [ for (i == 0) ]
      source1->dispatch() --> read(fd1);
  [ for (i == 1) ]
      source2->dispatch() --> read(fd2); /* blocking! */

Reading from fd2 will block, because we got only one signal,
and it was read from fd1.

Signed-off-by: Marek Chalupa <mchqwerty@gmail.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
This commit is contained in:
Marek Chalupa 2014-08-12 11:35:06 +02:00 committed by Pekka Paalanen
parent 5504c9338b
commit f2338c8f3b

View file

@ -233,7 +233,7 @@ wl_event_source_signal_dispatch(struct wl_event_source *source,
int len; int len;
len = read(source->fd, &signal_info, sizeof signal_info); len = read(source->fd, &signal_info, sizeof signal_info);
if (len != sizeof signal_info) if (!(len == -1 && errno == EAGAIN) && len != sizeof signal_info)
/* Is there anything we can do here? Will this ever happen? */ /* Is there anything we can do here? Will this ever happen? */
wl_log("signalfd read error: %m\n"); wl_log("signalfd read error: %m\n");
@ -263,7 +263,7 @@ wl_event_loop_add_signal(struct wl_event_loop *loop,
sigemptyset(&mask); sigemptyset(&mask);
sigaddset(&mask, signal_number); sigaddset(&mask, signal_number);
source->base.fd = signalfd(-1, &mask, SFD_CLOEXEC); source->base.fd = signalfd(-1, &mask, SFD_CLOEXEC | SFD_NONBLOCK);
sigprocmask(SIG_BLOCK, &mask, NULL); sigprocmask(SIG_BLOCK, &mask, NULL);
source->func = func; source->func = func;