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| author | Eric Dumazet <edumazet@google.com> | 2013-01-06 18:21:49 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-02-14 10:47:36 -0800 |
| commit | 9f557574821b44a87d95756bf53f1b7fb76eb4d4 (patch) | |
| tree | 2f4c7468ae9951c27428907f2ccd575532418ef1 | |
| parent | 31885683c218d57ff90d827a1be5c5d3cb4263ac (diff) | |
| download | lwn-9f557574821b44a87d95756bf53f1b7fb76eb4d4.tar.gz lwn-9f557574821b44a87d95756bf53f1b7fb76eb4d4.zip | |
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 <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>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | fs/splice.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/fs/splice.c b/fs/splice.c index 9d890085f9ba..ea92b7c51d4a 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -693,8 +693,10 @@ 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); } |