diff --git a/lib/libc/sys/kqueue.2 b/lib/libc/sys/kqueue.2 index 430722aa6089..c4079a9b4364 100644 --- a/lib/libc/sys/kqueue.2 +++ b/lib/libc/sys/kqueue.2 @@ -24,7 +24,7 @@ .\" .\" $FreeBSD$ .\" -.Dd April 21, 2020 +.Dd April 27, 2020 .Dt KQUEUE 2 .Os .Sh NAME @@ -323,8 +323,7 @@ When the last writer disconnects, the filter will set .Dv EV_EOF in .Va flags . -This may be cleared by passing in -.Dv EV_CLEAR , +This will be cleared by the filter when a new writer connects, at which point the filter will resume waiting for data to become available before returning. @@ -343,9 +342,10 @@ For sockets, pipes and fifos, .Va data will contain the amount of space remaining in the write buffer. -The filter will set EV_EOF when the reader disconnects, and for -the fifo case, this may be cleared by use of -.Dv EV_CLEAR . +The filter will set +.Dv EV_EOF +when the reader disconnects, and for the fifo case, this will be cleared +when a new reader connects. Note that this filter is not supported for vnodes or BPF devices. .Pp For sockets, the low water mark and socket error handling is diff --git a/sys/kern/sys_pipe.c b/sys/kern/sys_pipe.c index 229c00e3199d..216d0f077778 100644 --- a/sys/kern/sys_pipe.c +++ b/sys/kern/sys_pipe.c @@ -824,7 +824,12 @@ pipe_read(struct file *fp, struct uio *uio, struct ucred *active_cred, } } - if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF) + /* + * Only wake up writers if there was actually something read. + * Otherwise, when calling read(2) at EOF, a spurious wakeup occurs. + */ + if (nread > 0 && + rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt >= PIPE_BUF) pipeselwakeup(rpipe); PIPE_UNLOCK(rpipe); @@ -1726,48 +1731,54 @@ filt_pipedetach(struct knote *kn) static int filt_piperead(struct knote *kn, long hint) { + struct file *fp = kn->kn_fp; struct pipe *rpipe = kn->kn_hook; - struct pipe *wpipe = rpipe->pipe_peer; - int ret; PIPE_LOCK_ASSERT(rpipe, MA_OWNED); kn->kn_data = rpipe->pipe_buffer.cnt; if (kn->kn_data == 0) kn->kn_data = rpipe->pipe_map.cnt; - if ((rpipe->pipe_state & PIPE_EOF) || - wpipe->pipe_present != PIPE_ACTIVE || - (wpipe->pipe_state & PIPE_EOF)) { + if ((rpipe->pipe_state & PIPE_EOF) != 0 && + ((rpipe->pipe_state & PIPE_NAMED) == 0 || + fp->f_pipegen != rpipe->pipe_wgen)) { kn->kn_flags |= EV_EOF; return (1); } - ret = kn->kn_data > 0; - return ret; + kn->kn_flags &= ~EV_EOF; + return (kn->kn_data > 0); } /*ARGSUSED*/ static int filt_pipewrite(struct knote *kn, long hint) { - struct pipe *wpipe; + struct pipe *wpipe = kn->kn_hook; /* * If this end of the pipe is closed, the knote was removed from the * knlist and the list lock (i.e., the pipe lock) is therefore not held. */ - wpipe = kn->kn_hook; + if (wpipe->pipe_present == PIPE_ACTIVE || + (wpipe->pipe_state & PIPE_NAMED) != 0) { + PIPE_LOCK_ASSERT(wpipe, MA_OWNED); + + if (wpipe->pipe_state & PIPE_DIRECTW) { + kn->kn_data = 0; + } else if (wpipe->pipe_buffer.size > 0) { + kn->kn_data = wpipe->pipe_buffer.size - + wpipe->pipe_buffer.cnt; + } else { + kn->kn_data = PIPE_BUF; + } + } + if (wpipe->pipe_present != PIPE_ACTIVE || (wpipe->pipe_state & PIPE_EOF)) { - kn->kn_data = 0; kn->kn_flags |= EV_EOF; return (1); } - PIPE_LOCK_ASSERT(wpipe, MA_OWNED); - kn->kn_data = (wpipe->pipe_buffer.size > 0) ? - (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) : PIPE_BUF; - if (wpipe->pipe_state & PIPE_DIRECTW) - kn->kn_data = 0; - + kn->kn_flags &= ~EV_EOF; return (kn->kn_data >= PIPE_BUF); }