From: Eric Dumazet Date: Sun, 6 Jan 2013 18:21:49 +0000 (+0000) Subject: tcp: fix MSG_SENDPAGE_NOTLAST logic X-Git-Tag: v3.8-rc3~8^2~3 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=ae62ca7b03217be5e74759dc6d7698c95df498b3;p=profile%2Fcommon%2Fkernel-common.git tcp: fix MSG_SENDPAGE_NOTLAST logic 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 --- diff --git a/fs/splice.c b/fs/splice.c index 8890604..6909d89d0 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); }