On Sun, Dec 18, 2016 at 08:12:07PM +0000, Al Viro wrote:
> On Sun, Dec 18, 2016 at 11:28:44AM -0800, Linus Torvalds wrote:
> > On Sat, Dec 17, 2016 at 11:54 AM, Andreas Schwab <schwab@xxxxxxxxxxxxxx> wrote:
> > > This break EPIPE handling inside splice when SIGPIPE is ignored:
> > >
> > > Before:
> > > $ { sleep 1; strace -e splice pv -q /dev/zero; } | :
> >
> > Where is that "splice" program from? Google isn't helpful, and fedora
> > doesn't seem to have it. I'm assuming it was posted in one of the
> > threads, but if so I've long since lost sight of it..
>
> It's pv(1), actually. I'm looking into that - debian-packaged pv reproduced
> that crap.
OK, I see what's going on - it's wait_for_space() lifted past the checks
for lack of readers. The fix, AFAICS, is simply
diff --git a/fs/splice.c b/fs/splice.c
index 6a2b0db5..aeba2b7 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1082,6 +1082,10 @@ EXPORT_SYMBOL(do_splice_direct);
static int wait_for_space(struct pipe_inode_info *pipe, unsigned flags)
{
+ if (unlikely(!pipe->readers)) {
+ send_sig(SIGPIPE, current, 0);
+ return -EPIPE;
+ }
while (pipe->nrbufs == pipe->buffers) {
if (flags & SPLICE_F_NONBLOCK)
return -EAGAIN;
@@ -1090,6 +1094,10 @@ static int wait_for_space(struct pipe_inode_info *pipe, unsigned flags)
pipe->waiting_writers++;
pipe_wait(pipe);
pipe->waiting_writers--;
+ if (unlikely(!pipe->readers)) {
+ send_sig(SIGPIPE, current, 0);
+ return -EPIPE;
+ }
}
return 0;
}
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