Re: [PATCH 04/12] splice: lift pipe_lock out of splice_to_pipe()

[Andreas Schwab <schwab@xxxxxxxxxxxxxx>]

On Dez 18 2016, Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:

> Regardless - Andreas, can you verify that that fixes your issues? I'm
> assuming you had some real load that made you notice this, not just he
> dummy example..

FWIW, I have verified that the testsuite of pv succeeds with this patch:

diff --git a/fs/splice.c b/fs/splice.c
index 5a7750bd2e..63b8f54485 100644
--- 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_inode_info *pipe, 
unsigned flags)
                pipe_wait(pipe);
                pipe->waiting_writers--;
        }
-       return 0;
 }
 
 static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
-- 
2.11.0


Andreas.

-- 
Andreas Schwab, schwab@xxxxxxxxxxxxxx
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