Messages in this thread Patch in this message |  | | Subject | [PATCH] tcp: fix MSG_SENDPAGE_NOTLAST logic | From | Eric Dumazet <> | Date | Sun, 06 Jan 2013 20:21:49 -0800 |
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From: Eric Dumazet <edumazet@google.com>
commit 35f9c09fe9c72e (tcp: tcp_sendpages() should call tcp_push() once) added an internal flag : MSG_SENDPAGE_NOTLAST meant to be set on all frags but the last one for a splice() call.
The condition used to set the flag in pipe_to_sendpage() relied on splice() user passing the exact number of bytes present in the pipe, or a smaller one.
But some programs pass an arbitrary high value, and the test fails.
The effect of this bug is a lack of tcp_push() at the end of a splice(pipe -> socket) call, and possibly very slow or erratic TCP sessions.
We should both test sd->total_len and fact that another fragment is in the pipe (pipe->nrbufs > 1)
Many thanks to Willy for providing very clear bug report, bisection and test programs.
Reported-by: Willy Tarreau <w@1wt.eu> Bisected-by: Willy Tarreau <w@1wt.eu> Tested-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Eric Dumazet <edumazet@google.com> --- fs/splice.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/splice.c b/fs/splice.c index 8890604..6909d89 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -696,8 +696,10 @@ static int pipe_to_sendpage(struct pipe_inode_info *pipe, return -EINVAL; more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0; - if (sd->len < sd->total_len) + + if (sd->len < sd->total_len && pipe->nrbufs > 1) more |= MSG_SENDPAGE_NOTLAST; + return file->f_op->sendpage(file, buf->page, buf->offset, sd->len, &pos, more); }
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