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tcp: tcp_sendpages() should call tcp_push() once

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commit 2f53384424 (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>
This commit is contained in:
Eric Dumazet 2012-04-05 03:05:35 +00:00 • committed by David S. Miller
commit 35f9c09fe9
4 changed files with 9 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

5
fs/splice.c
View file

@ -30,6 +30,7 @@
#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
@ -690,7 +691,9 @@ static int pipe_to_sendpage(struct pipe_inode_info *pipe,
if (!likely(file->f_op && file->f_op->sendpage))
return -EINVAL;
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;
return file->f_op->sendpage(file, buf->page, buf->offset,
sd->len, &pos, more);
}

2
include/linux/socket.h
View file

@ -265,7 +265,7 @@ 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

2
net/ipv4/tcp.c
View file

@ -860,7 +860,7 @@ 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;

6
net/socket.c
View file

@ -811,9 +811,9 @@ 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);
}