From: Eric Dumazet Date: Sun, 6 Jan 2013 18:21:49 +0000 (+0000) Subject: tcp: fix MSG_SENDPAGE_NOTLAST logic X-Git-Tag: v3.2.39~5 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=f507e6ef54020383b4012778606f84b1e22f4667;hp=4670ea19f63e7db7ca352e68e120e82e3c135fbb tcp: fix MSG_SENDPAGE_NOTLAST logic [ 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: Ben Hutchings --- diff --git a/fs/splice.c b/fs/splice.c index 014fcb48744a..58ab918afb4c 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -697,8 +697,10 @@ 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); }