lkml.org 
[lkml]   [2014]   [Feb]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[v2.6.34-stable 040/213] tcp: tcp_sendpages() should call tcp_push() once
Date
From: Eric Dumazet <eric.dumazet@gmail.com>

-------------------
This is a commit scheduled for the next v2.6.34 longterm release.
http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git
If you see a problem with using this for longterm, please comment.
-------------------

commit 35f9c09fe9c72eb8ca2b8e89a593e1c151f28fc2 upstream.

commit 2f533844242 (tcp: allow splice() to build full TSO packets) added
a regression for splice() calls using SPLICE_F_MORE.

We need to call tcp_flush() at the end of the last page processed in
tcp_sendpages(), or else transmits can be deferred and future sends
stall.

Add a new internal flag, MSG_SENDPAGE_NOTLAST, acting like MSG_MORE, but
with different semantic.

For all sendpage() providers, its a transparent change. Only
sock_sendpage() and tcp_sendpages() can differentiate the two different
flags provided by pipe_to_sendpage()

Reported-by: Tom Herbert <therbert@google.com>
Cc: Nandita Dukkipati <nanditad@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: H.K. Jerry Chu <hkchu@google.com>
Cc: Maciej Żenczykowski <maze@google.com>
Cc: Mahesh Bandewar <maheshb@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail>com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
fs/splice.c | 5 ++++-
include/linux/socket.h | 2 +-
net/ipv4/tcp.c | 2 +-
net/socket.c | 6 +++---
4 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/fs/splice.c b/fs/splice.c
index cc617b09e4c2..3bec7c63be64 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -31,6 +31,7 @@
#include <linux/uio.h>
#include <linux/security.h>
#include <linux/gfp.h>
+#include <linux/socket.h>

/*
* Attempt to steal a page from a pipe buffer. This should perhaps go into
@@ -638,7 +639,9 @@ static int pipe_to_sendpage(struct pipe_inode_info *pipe,

ret = buf->ops->confirm(pipe, buf);
if (!ret) {
- more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len;
+ more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0;
+ if (sd->len < sd->total_len)
+ 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);
diff --git a/include/linux/socket.h b/include/linux/socket.h
index 354cc5617f8b..7cfb4f881644 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -256,7 +256,7 @@ struct ucred {
#define MSG_NOSIGNAL 0x4000 /* Do not generate SIGPIPE */
#define MSG_MORE 0x8000 /* Sender will send more */
#define MSG_WAITFORONE 0x10000 /* recvmmsg(): block until 1+ packets avail */
-
+#define MSG_SENDPAGE_NOTLAST 0x20000 /* sendpage() internal : not the last page */
#define MSG_EOF MSG_FIN

#define MSG_CMSG_CLOEXEC 0x40000000 /* Set close_on_exit for file
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index cea0a9223c5d..df671c76f196 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -849,7 +849,7 @@ wait_for_memory:
}

out:
- if (copied && !(flags & MSG_MORE))
+ if (copied && !(flags & MSG_SENDPAGE_NOTLAST))
tcp_push(sk, flags, mss_now, tp->nonagle);
return copied;

diff --git a/net/socket.c b/net/socket.c
index c63ebf4e31b5..c802797e3a4a 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -746,9 +746,9 @@ static ssize_t sock_sendpage(struct file *file, struct page *page,

sock = file->private_data;

- flags = !(file->f_flags & O_NONBLOCK) ? 0 : MSG_DONTWAIT;
- if (more)
- flags |= MSG_MORE;
+ flags = (file->f_flags & O_NONBLOCK) ? MSG_DONTWAIT : 0;
+ /* more is a combination of MSG_MORE and MSG_SENDPAGE_NOTLAST */
+ flags |= more;

return kernel_sendpage(sock, page, offset, size, flags);
}
--
1.8.5.2
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2014-02-05 23:01    [W:0.488 / U:0.156 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site