https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=203366
Bug ID: 203366 Summary: kevent: EV_CLEAR on fifo does not work correctly Product: Base System Version: 10.2-STABLE Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: freebsd-bugs@FreeBSD.org Reporter: m...@markoturk.info Hi, according to kqueue(2) man page for EVFILT_READ on a fifo: "When the last writer disconnects, the filter will set EV_EOF in flags. This may be cleared by passing in EV_CLEAR, at which point the filter will resume waiting for data to become available before returning." But, EV_CLEAR on fifo does not work (EV_EOF is returned). To reproduce (tail uses kevent and EV_CLEAR internally): mkfifo foo tail -f foo (in another terminal:) echo xxx > foo After this, top process uses all CPU. I tried to fix the bug. After applying this patch the problem is not visible, but I'm not sure if this is the correct solution: Index: sys/kern/sys_pipe.c =================================================================== --- sys/kern/sys_pipe.c (revision 288220) +++ sys/kern/sys_pipe.c (working copy) @@ -1791,9 +1791,10 @@ if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW)) kn->kn_data = rpipe->pipe_map.cnt; - if ((rpipe->pipe_state & PIPE_EOF) || + if (!(kn->kn_flags & EV_CLEAR) && + ((rpipe->pipe_state & PIPE_EOF) || wpipe->pipe_present != PIPE_ACTIVE || - (wpipe->pipe_state & PIPE_EOF)) { + (wpipe->pipe_state & PIPE_EOF))) { kn->kn_flags |= EV_EOF; return (1); } -- You are receiving this mail because: You are the assignee for the bug. _______________________________________________ freebsd-bugs@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-bugs To unsubscribe, send any mail to "freebsd-bugs-unsubscr...@freebsd.org"