4e3a47a4cb
Fix a race condition when do_sigchld, uloop_cancelled were set just before epoll_wait(timeout=-1), resulting the loop stuck in the syscall without noticing the events just happened Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com> Signed-off-by: Felix Fietkau <nbd@nbd.name>
148 lines
3.4 KiB
C
148 lines
3.4 KiB
C
/*
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* uloop - event loop implementation
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*
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* Copyright (C) 2010-2016 Felix Fietkau <nbd@openwrt.org>
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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static int uloop_init_pollfd(void)
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{
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struct timespec timeout = { 0, 0 };
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struct kevent ev = {};
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if (poll_fd >= 0)
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return 0;
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poll_fd = kqueue();
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if (poll_fd < 0)
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return -1;
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EV_SET(&ev, SIGCHLD, EVFILT_SIGNAL, EV_ADD, 0, 0, 0);
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kevent(poll_fd, &ev, 1, NULL, 0, &timeout);
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return 0;
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}
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static uint16_t get_flags(unsigned int flags, unsigned int mask)
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{
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uint16_t kflags = 0;
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if (!(flags & mask))
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return EV_DELETE;
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kflags = EV_ADD;
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if (flags & ULOOP_EDGE_TRIGGER)
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kflags |= EV_CLEAR;
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return kflags;
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}
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static struct kevent events[ULOOP_MAX_EVENTS];
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static int register_kevent(struct uloop_fd *fd, unsigned int flags)
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{
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struct timespec timeout = { 0, 0 };
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struct kevent ev[2];
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int nev = 0;
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unsigned int fl = 0;
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unsigned int changed;
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uint16_t kflags;
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if (flags & ULOOP_EDGE_DEFER)
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flags &= ~ULOOP_EDGE_TRIGGER;
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changed = flags ^ fd->flags;
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if (changed & ULOOP_EDGE_TRIGGER)
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changed |= flags;
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if (changed & ULOOP_READ) {
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kflags = get_flags(flags, ULOOP_READ);
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EV_SET(&ev[nev++], fd->fd, EVFILT_READ, kflags, 0, 0, fd);
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}
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if (changed & ULOOP_WRITE) {
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kflags = get_flags(flags, ULOOP_WRITE);
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EV_SET(&ev[nev++], fd->fd, EVFILT_WRITE, kflags, 0, 0, fd);
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}
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if (!flags)
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fl |= EV_DELETE;
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fd->flags = flags;
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if (kevent(poll_fd, ev, nev, NULL, fl, &timeout) == -1)
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return -1;
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return 0;
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}
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static int register_poll(struct uloop_fd *fd, unsigned int flags)
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{
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if (flags & ULOOP_EDGE_TRIGGER)
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flags |= ULOOP_EDGE_DEFER;
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else
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flags &= ~ULOOP_EDGE_DEFER;
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return register_kevent(fd, flags);
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}
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static int __uloop_fd_delete(struct uloop_fd *fd)
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{
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return register_poll(fd, 0);
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}
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static int uloop_fetch_events(int timeout)
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{
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struct timespec ts;
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int nfds, n;
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if (timeout >= 0) {
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ts.tv_sec = timeout / 1000;
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ts.tv_nsec = (timeout % 1000) * 1000000;
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}
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nfds = kevent(poll_fd, NULL, 0, events, ARRAY_SIZE(events), timeout >= 0 ? &ts : NULL);
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for (n = 0; n < nfds; n++) {
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struct uloop_fd_event *cur = &cur_fds[n];
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struct uloop_fd *u = events[n].udata;
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unsigned int ev = 0;
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cur->fd = u;
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if (!u)
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continue;
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if (events[n].flags & EV_ERROR) {
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u->error = true;
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if (!(u->flags & ULOOP_ERROR_CB))
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uloop_fd_delete(u);
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}
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if(events[n].filter == EVFILT_READ)
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ev |= ULOOP_READ;
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else if (events[n].filter == EVFILT_WRITE)
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ev |= ULOOP_WRITE;
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if (events[n].flags & EV_EOF)
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u->eof = true;
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else if (!ev)
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cur->fd = NULL;
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cur->events = ev;
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if (u->flags & ULOOP_EDGE_DEFER) {
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u->flags &= ~ULOOP_EDGE_DEFER;
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u->flags |= ULOOP_EDGE_TRIGGER;
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register_kevent(u, u->flags);
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}
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}
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return nfds;
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}
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