Patch "splice: reinstate SIGPIPE/EPIPE handling" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    splice: reinstate SIGPIPE/EPIPE handling

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     splice-reinstate-sigpipe-epipe-handling.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 52bce91165e5f2db422b2b972e83d389e5e4725c Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Wed, 21 Dec 2016 10:59:34 -0800
Subject: splice: reinstate SIGPIPE/EPIPE handling

From: Linus Torvalds <torvalds@linux-foundation.org>

commit 52bce91165e5f2db422b2b972e83d389e5e4725c upstream.

Commit 8924feff66f3 ("splice: lift pipe_lock out of splice_to_pipe()")
caused a regression when there were no more readers left on a pipe that
was being spliced into: rather than the expected SIGPIPE and -EPIPE
return value, the writer would end up waiting forever for space to free
up (which obviously was not going to happen with no readers around).

Fixes: 8924feff66f3 ("splice: lift pipe_lock out of splice_to_pipe()")
Reported-and-tested-by: Andreas Schwab <schwab@linux-m68k.org>
Debugged-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/splice.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1086,7 +1086,13 @@ EXPORT_SYMBOL(do_splice_direct);
 
 static int wait_for_space(struct pipe_inode_info *pipe, unsigned flags)
 {
-	while (pipe->nrbufs == pipe->buffers) {
+	for (;;) {
+		if (unlikely(!pipe->readers)) {
+			send_sig(SIGPIPE, current, 0);
+			return -EPIPE;
+		}
+		if (pipe->nrbufs != pipe->buffers)
+			return 0;
 		if (flags & SPLICE_F_NONBLOCK)
 			return -EAGAIN;
 		if (signal_pending(current))
@@ -1095,7 +1101,6 @@ static int wait_for_space(struct pipe_in
 		pipe_wait(pipe);
 		pipe->waiting_writers--;
 	}
-	return 0;
 }
 
 static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,


Patches currently in stable-queue which might be from torvalds@linux-foundation.org are

queue-4.9/mm-page_alloc-keep-pcp-count-and-list-contents-in-sync-if-struct-page-is-corrupted.patch
queue-4.9/splice-reinstate-sigpipe-epipe-handling.patch
queue-4.9/mm-vmscan.c-set-correct-defer-count-for-shrinker.patch
queue-4.9/vfs-mm-fix-return-value-of-read-at-s_maxbytes.patch