4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Linus Torvalds <torva...@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 <sch...@linux-m68k.org>
Debugged-by: Al Viro <v...@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gre...@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,
