Date: Mon, 06 Sep 2021 10:50:30 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 258310] kevent() does not see signal with zero timeout Message-ID: <bug-258310-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D258310 Bug ID: 258310 Summary: kevent() does not see signal with zero timeout Product: Base System Version: 13.0-RELEASE Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: arichardson@FreeBSD.org While adding patches to natively support FreeBSD in wayland, I noticed that epoll-shim (used to emulate epoll with kqueue) didn't report signals sent to self via kill() unless I added a non-zero timeout (even in a single-threaded test program). In https://github.com/jiixyj/epoll-shim/pull/32=20 Jan Kokem=C3=BCller provided a reduced test case using only kqueue and keve= nt: ``` #ifdef NDEBUG #undef NDEBUG #endif #define _GNU_SOURCE #include <sys/types.h> #include <sys/event.h> #include <assert.h> #include <errno.h> #include <signal.h> #include <stdlib.h> #include <poll.h> #include <unistd.h> int main(void) { int rv; sigset_t set; rv =3D sigemptyset(&set); assert(rv =3D=3D 0); rv =3D sigaddset(&set, SIGUSR1); assert(rv =3D=3D 0); rv =3D sigprocmask(SIG_BLOCK, &set, NULL); assert(rv =3D=3D 0); int skq =3D kqueue(); assert(skq >=3D 0); struct kevent kev; EV_SET(&kev, SIGUSR1, EVFILT_SIGNAL, EV_ADD, 0, 0, 0); rv =3D kevent(skq, &kev, 1, NULL, 0, NULL); assert(rv =3D=3D 0); int kq =3D kqueue(); assert(kq >=3D 0); EV_SET(&kev, skq, EVFILT_READ, EV_ADD | EV_CLEAR, 0, 0, 0); rv =3D kevent(kq, &kev, 1, NULL, 0, NULL); assert(rv =3D=3D 0); for (;;) { rv =3D kill(getpid(), SIGUSR1); assert(rv =3D=3D 0); /* Turn this into `#if 1` to avoid the race. */ #if 0 rv =3D kevent(kq, NULL, 0, &kev, 1, NULL); #else rv =3D kevent(kq, NULL, 0, &kev, 1, &(struct timespec) { 0,= 0 }); #endif assert(rv =3D=3D 1); rv =3D kevent(kq, NULL, 0, &kev, 1, &(struct timespec) { 0,= 0 }); assert(rv =3D=3D 0); rv =3D kevent(skq, NULL, 0, &kev, 1, &(struct timespec) { 0= , 0 }); assert(rv =3D=3D 1); rv =3D kevent(skq, NULL, 0, &kev, 1, &(struct timespec) { 0= , 0 }); assert(rv =3D=3D 0); siginfo_t siginfo; rv =3D sigtimedwait(&set, &siginfo, &(struct timespec) { 0,= 0 }); assert(rv =3D=3D SIGUSR1); rv =3D sigtimedwait(&set, &siginfo, &(struct timespec) { 0,= 0 }); assert(rv < 0); assert(errno =3D=3D EAGAIN); } } ``` Is this behaviour expected or a bug? --=20 You are receiving this mail because: You are the assignee for the bug.=
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