From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753573Ab3FDWnE (ORCPT ); Tue, 4 Jun 2013 18:43:04 -0400 Received: from 1wt.eu ([62.212.114.60]:35624 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753497Ab3FDWm7 (ORCPT ); Tue, 4 Jun 2013 18:42:59 -0400 Message-Id: <20130604172136.892217862@1wt.eu> User-Agent: quilt/0.48-1 Date: Tue, 04 Jun 2013 19:24:09 +0200 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Eric Dumazet , "David S. Miller" , Greg Kroah-Hartman , Willy Tarreau Subject: [ 159/184] tcp: fix MSG_SENDPAGE_NOTLAST logic In-Reply-To: <58df134a4b98edf5b0073e2e1e988fe6@local> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.32-longterm review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit ae62ca7b03217be5e74759dc6d7698c95df498b3 ] 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 Bisected-by: Willy Tarreau Tested-by: Willy Tarreau Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman Signed-off-by: Willy Tarreau --- fs/splice.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/splice.c b/fs/splice.c index f5d5a2b..cdad986 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -639,8 +639,10 @@ static int pipe_to_sendpage(struct pipe_inode_info *pipe, ret = buf->ops->confirm(pipe, buf); if (!ret) { 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; + if (file->f_op && file->f_op->sendpage) ret = file->f_op->sendpage(file, buf->page, buf->offset, sd->len, &pos, more); -- 1.7.12.2.21.g234cd45.dirty