Attachment 190730 Details for Bug 203366 – patch for FIFO related poll/kqueue issues

[patch] patch for FIFO related poll/kqueue issues

fifo-kqueue-issues.patch (text/plain), 2.84 KB, created by Jan Kokemüller on 2018-02-17 11:52:06 UTC

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Creator: Jan Kokemüller

Created: 2018-02-17 11:52:06 UTC

Size: 2.84 KB

patch

obsolete

>diff --git a/sys/fs/fifofs/fifo_vnops.c b/sys/fs/fifofs/fifo_vnops.c
>index 96dd05a18323..a39d559631bc 100644
>--- a/sys/fs/fifofs/fifo_vnops.c
>+++ b/sys/fs/fifofs/fifo_vnops.c
>@@ -171,8 +171,10 @@ fifo_open(ap)
> 		fip->fi_rgen++;
> 		if (fip->fi_readers == 1) {
> 			fpipe->pipe_state &= ~PIPE_EOF;
>-			if (fip->fi_writers > 0)
>+			if (fip->fi_writers > 0) {
> 				wakeup(&fip->fi_writers);
>+				pipeselwakeup(fpipe);
>+			}
> 		}
> 		fp->f_seqcount = fpipe->pipe_wgen - fip->fi_writers;
> 	}
>@@ -187,8 +189,10 @@ fifo_open(ap)
> 		fip->fi_wgen++;
> 		if (fip->fi_writers == 1) {
> 			fpipe->pipe_state &= ~PIPE_EOF;
>-			if (fip->fi_readers > 0)
>+			if (fip->fi_readers > 0) {
> 				wakeup(&fip->fi_readers);
>+				pipeselwakeup(fpipe);
>+			}
> 		}
> 	}
> 	if ((ap->a_mode & O_NONBLOCK) == 0) {
>diff --git a/sys/kern/sys_pipe.c b/sys/kern/sys_pipe.c
>index 469f5243635d..57fa296bfd69 100644
>--- a/sys/kern/sys_pipe.c
>+++ b/sys/kern/sys_pipe.c
>@@ -823,7 +823,13 @@ pipe_read(fp, uio, active_cred, flags, td)
> 		}
> 	}
> 
>-	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
>+	 * that might lead to issues like PR 203366.
>+	 */
>+	if (nread > 0 &&
>+	    (rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF)
> 		pipeselwakeup(rpipe);
> 
> 	PIPE_UNLOCK(rpipe);
>@@ -1461,7 +1467,8 @@ pipe_poll(fp, events, active_cred, td)
> 
> 	if ((events & POLLINIGNEOF) == 0) {
> 		if (rpipe->pipe_state & PIPE_EOF) {
>-			revents |= (events & (POLLIN | POLLRDNORM));
>+			if (fp->f_flag & FREAD)
>+				revents |= (events & (POLLIN | POLLRDNORM));
> 			if (wpipe->pipe_present != PIPE_ACTIVE ||
> 			    (wpipe->pipe_state & PIPE_EOF))
> 				revents |= POLLHUP;
>@@ -1788,23 +1795,22 @@ 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) && (rpipe->pipe_state & PIPE_DIRECTW))
> 		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) &&
>+	    !((rpipe->pipe_state & PIPE_NAMED) &&
>+	        (fp->f_seqcount == 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*/
>@@ -1821,6 +1827,7 @@ filt_pipewrite(struct knote *kn, long hint)
> 		kn->kn_flags |= EV_EOF;
> 		return (1);
> 	}
>+	kn->kn_flags &= ~EV_EOF;
> 	kn->kn_data = (wpipe->pipe_buffer.size > 0) ?
> 	    (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) : PIPE_BUF;
> 	if (wpipe->pipe_state & PIPE_DIRECTW)

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Attachments on bug 203366: 162301 | 167574 | 188967 | 190730