This patch does not get rid of ncalls, which I'm also thinking of doing, as I mentioned in an earlier message to the list.
devpoll.c | 15 +++-------- epoll.c | 15 +++-------- evport.c | 17 +++---------- evsignal.h | 8 ++---- poll.c | 15 +++-------- select.c | 14 +++-------signal.c | 74 +++++++++++++++ +-----------------------------------------
test/regress.c | 32 ++++++++++++++++++++++++ 8 files changed, 76 insertions(+), 114 deletions(-)There's one subtlety to it. With my change, evsignal_process() runs with signals unblocked, so timing is critical. The original code is then racy:
TAILQ_FOREACH(ev, &signalqueue, ev_signal_next) {
ncalls = evsigcaught[EVENT_SIGNAL(ev)]; <-- point A
if (ncalls) {
if (!(ev->ev_events & EV_PERSIST))
event_del(ev);
event_active(ev, EV_SIGNAL, ncalls);
}
}
memset(evsigcaught, 0, sizeof(evsigcaught)); <-- point B
evsignal_caught = 0; <-- point C
For any signal that is not already pending (ncalls == 0 when reaching
its point A), if it arrives between then and its ncalls being cleared
in point B, it will be lost. If it arrives after then but before
evsignal_caught in point C, it will be arbitrarily delayed (until
another signal comes along to set evsignal_caught).
I solved this by* moving the evsignal_caught to before checking the individual signals for delivery (but after evsignal_caught is checked itself, in a different function). * setting "evsigcaught[x] = 0" only when we are setting that signal active.
-- Scott Lamb <http://www.slamb.org/>
event-signal.patch
Description: Binary data
_______________________________________________ Libevent-users mailing list Libevent-users@monkey.org http://monkey.org/mailman/listinfo/libevent-users
