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75c2d9077c
linux/net/ipv4/tcp.c
Herbert Xu 75c2d9077c [TCP]: Fix sock_orphan dead lock 
Calling sock_orphan inside bh_lock_sock in tcp_close can lead to dead
locks.  For example, the inet_diag code holds sk_callback_lock without
disabling BH.  If an inbound packet arrives during that admittedly tiny
window, it will cause a dead lock on bh_lock_sock.  Another possible
path would be through sock_wfree if the network device driver frees the
tx skb in process context with BH enabled.

We can fix this by moving sock_orphan out of bh_lock_sock.

The tricky bit is to work out when we need to destroy the socket
ourselves and when it has already been destroyed by someone else.

By moving sock_orphan before the release_sock we can solve this
problem.  This is because as long as we own the socket lock its
state cannot change.

So we simply record the socket state before the release_sock
and then check the state again after we regain the socket lock.
If the socket state has transitioned to TCP_CLOSE in the time being,
we know that the socket has been destroyed.  Otherwise the socket is
still ours to keep.

Note that I've also moved the increment on the orphan count forward.
This may look like a problem as we're increasing it even if the socket
is just about to be destroyed where it'll be decreased again.  However,
this simply enlarges a window that already exists.  This also changes
the orphan count test by one.

Considering what the orphan count is meant to do this is no big deal.

This problem was discoverd by Ingo Molnar using his lock validator.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-05-03 23:31:35 -07:00

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/*
* INET An implementation of the TCP/IP protocol suite for the LINUX
* operating system. INET is implemented using the BSD Socket
* interface as the means of communication with the user level.
*
* Implementation of the Transmission Control Protocol(TCP).
*
* Version: $Id: tcp.c,v 1.216 2002/02/01 22:01:04 davem Exp $
*
* Authors: Ross Biro
* Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
* Mark Evans, <evansmp@uhura.aston.ac.uk>
* Corey Minyard <wf-rch!minyard@relay.EU.net>
* Florian La Roche, <flla@stud.uni-sb.de>
* Charles Hedrick, <hedrick@klinzhai.rutgers.edu>
* Linus Torvalds, <torvalds@cs.helsinki.fi>
* Alan Cox, <gw4pts@gw4pts.ampr.org>
* Matthew Dillon, <dillon@apollo.west.oic.com>
* Arnt Gulbrandsen, <agulbra@nvg.unit.no>
* Jorge Cwik, <jorge@laser.satlink.net>
*
* Fixes:
* Alan Cox : Numerous verify_area() calls
* Alan Cox : Set the ACK bit on a reset
* Alan Cox : Stopped it crashing if it closed while
* sk->inuse=1 and was trying to connect
* (tcp_err()).
* Alan Cox : All icmp error handling was broken
* pointers passed where wrong and the
* socket was looked up backwards. Nobody
* tested any icmp error code obviously.
* Alan Cox : tcp_err() now handled properly. It
* wakes people on errors. poll
* behaves and the icmp error race
* has gone by moving it into sock.c
* Alan Cox : tcp_send_reset() fixed to work for
* everything not just packets for
* unknown sockets.
* Alan Cox : tcp option processing.
* Alan Cox : Reset tweaked (still not 100%) [Had
* syn rule wrong]
* Herp Rosmanith : More reset fixes
* Alan Cox : No longer acks invalid rst frames.
* Acking any kind of RST is right out.
* Alan Cox : Sets an ignore me flag on an rst
* receive otherwise odd bits of prattle
* escape still
* Alan Cox : Fixed another acking RST frame bug.
* Should stop LAN workplace lockups.
* Alan Cox : Some tidyups using the new skb list
* facilities
* Alan Cox : sk->keepopen now seems to work
* Alan Cox : Pulls options out correctly on accepts
* Alan Cox : Fixed assorted sk->rqueue->next errors
* Alan Cox : PSH doesn't end a TCP read. Switched a
* bit to skb ops.
* Alan Cox : Tidied tcp_data to avoid a potential
* nasty.
* Alan Cox : Added some better commenting, as the
* tcp is hard to follow
* Alan Cox : Removed incorrect check for 20 * psh
* Michael O'Reilly : ack < copied bug fix.
* Johannes Stille : Misc tcp fixes (not all in yet).
* Alan Cox : FIN with no memory -> CRASH
* Alan Cox : Added socket option proto entries.
* Also added awareness of them to accept.
* Alan Cox : Added TCP options (SOL_TCP)
* Alan Cox : Switched wakeup calls to callbacks,
* so the kernel can layer network
* sockets.
* Alan Cox : Use ip_tos/ip_ttl settings.
* Alan Cox : Handle FIN (more) properly (we hope).
* Alan Cox : RST frames sent on unsynchronised
* state ack error.
* Alan Cox : Put in missing check for SYN bit.
* Alan Cox : Added tcp_select_window() aka NET2E
* window non shrink trick.
* Alan Cox : Added a couple of small NET2E timer
* fixes
* Charles Hedrick : TCP fixes
* Toomas Tamm : TCP window fixes
* Alan Cox : Small URG fix to rlogin ^C ack fight
* Charles Hedrick : Rewrote most of it to actually work
* Linus : Rewrote tcp_read() and URG handling
* completely
* Gerhard Koerting: Fixed some missing timer handling
* Matthew Dillon : Reworked TCP machine states as per RFC
* Gerhard Koerting: PC/TCP workarounds
* Adam Caldwell : Assorted timer/timing errors
* Matthew Dillon : Fixed another RST bug
* Alan Cox : Move to kernel side addressing changes.
* Alan Cox : Beginning work on TCP fastpathing
* (not yet usable)
* Arnt Gulbrandsen: Turbocharged tcp_check() routine.
* Alan Cox : TCP fast path debugging
* Alan Cox : Window clamping
* Michael Riepe : Bug in tcp_check()
* Matt Dillon : More TCP improvements and RST bug fixes
* Matt Dillon : Yet more small nasties remove from the
* TCP code (Be very nice to this man if
* tcp finally works 100%) 8)
* Alan Cox : BSD accept semantics.
* Alan Cox : Reset on closedown bug.
* Peter De Schrijver : ENOTCONN check missing in tcp_sendto().
* Michael Pall : Handle poll() after URG properly in
* all cases.
* Michael Pall : Undo the last fix in tcp_read_urg()
* (multi URG PUSH broke rlogin).
* Michael Pall : Fix the multi URG PUSH problem in
* tcp_readable(), poll() after URG
* works now.
* Michael Pall : recv(...,MSG_OOB) never blocks in the
* BSD api.
* Alan Cox : Changed the semantics of sk->socket to
* fix a race and a signal problem with
* accept() and async I/O.
* Alan Cox : Relaxed the rules on tcp_sendto().
* Yury Shevchuk : Really fixed accept() blocking problem.
* Craig I. Hagan : Allow for BSD compatible TIME_WAIT for
* clients/servers which listen in on
* fixed ports.
* Alan Cox : Cleaned the above up and shrank it to
* a sensible code size.
* Alan Cox : Self connect lockup fix.
* Alan Cox : No connect to multicast.
* Ross Biro : Close unaccepted children on master
* socket close.
* Alan Cox : Reset tracing code.
* Alan Cox : Spurious resets on shutdown.
* Alan Cox : Giant 15 minute/60 second timer error
* Alan Cox : Small whoops in polling before an
* accept.
* Alan Cox : Kept the state trace facility since
* it's handy for debugging.
* Alan Cox : More reset handler fixes.
* Alan Cox : Started rewriting the code based on
* the RFC's for other useful protocol
* references see: Comer, KA9Q NOS, and
* for a reference on the difference
* between specifications and how BSD
* works see the 4.4lite source.
* A.N.Kuznetsov : Don't time wait on completion of tidy
* close.
* Linus Torvalds : Fin/Shutdown & copied_seq changes.
* Linus Torvalds : Fixed BSD port reuse to work first syn
* Alan Cox : Reimplemented timers as per the RFC
* and using multiple timers for sanity.
* Alan Cox : Small bug fixes, and a lot of new
* comments.
* Alan Cox : Fixed dual reader crash by locking
* the buffers (much like datagram.c)
* Alan Cox : Fixed stuck sockets in probe. A probe
* now gets fed up of retrying without
* (even a no space) answer.
* Alan Cox : Extracted closing code better
* Alan Cox : Fixed the closing state machine to
* resemble the RFC.
* Alan Cox : More 'per spec' fixes.
* Jorge Cwik : Even faster checksumming.
* Alan Cox : tcp_data() doesn't ack illegal PSH
* only frames. At least one pc tcp stack
* generates them.
* Alan Cox : Cache last socket.
* Alan Cox : Per route irtt.
* Matt Day : poll()->select() match BSD precisely on error
* Alan Cox : New buffers
* Marc Tamsky : Various sk->prot->retransmits and
* sk->retransmits misupdating fixed.
* Fixed tcp_write_timeout: stuck close,
* and TCP syn retries gets used now.
* Mark Yarvis : In tcp_read_wakeup(), don't send an
* ack if state is TCP_CLOSED.
* Alan Cox : Look up device on a retransmit - routes may
* change. Doesn't yet cope with MSS shrink right
* but it's a start!
* Marc Tamsky : Closing in closing fixes.
* Mike Shaver : RFC1122 verifications.
* Alan Cox : rcv_saddr errors.
* Alan Cox : Block double connect().
* Alan Cox : Small hooks for enSKIP.
* Alexey Kuznetsov: Path MTU discovery.
* Alan Cox : Support soft errors.
* Alan Cox : Fix MTU discovery pathological case
* when the remote claims no mtu!
* Marc Tamsky : TCP_CLOSE fix.
* Colin (G3TNE) : Send a reset on syn ack replies in
* window but wrong (fixes NT lpd problems)
* Pedro Roque : Better TCP window handling, delayed ack.
* Joerg Reuter : No modification of locked buffers in
* tcp_do_retransmit()
* Eric Schenk : Changed receiver side silly window
* avoidance algorithm to BSD style
* algorithm. This doubles throughput
* against machines running Solaris,
* and seems to result in general
* improvement.
* Stefan Magdalinski : adjusted tcp_readable() to fix FIONREAD
* Willy Konynenberg : Transparent proxying support.
* Mike McLagan : Routing by source
* Keith Owens : Do proper merging with partial SKB's in
* tcp_do_sendmsg to avoid burstiness.
* Eric Schenk : Fix fast close down bug with
* shutdown() followed by close().
* Andi Kleen : Make poll agree with SIGIO
* Salvatore Sanfilippo : Support SO_LINGER with linger == 1 and
* lingertime == 0 (RFC 793 ABORT Call)
* Hirokazu Takahashi : Use copy_from_user() instead of
* csum_and_copy_from_user() if possible.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or(at your option) any later version.
*
* Description of States:
*
* TCP_SYN_SENT sent a connection request, waiting for ack
*
* TCP_SYN_RECV received a connection request, sent ack,
* waiting for final ack in three-way handshake.
*
* TCP_ESTABLISHED connection established
*
* TCP_FIN_WAIT1 our side has shutdown, waiting to complete
* transmission of remaining buffered data
*
* TCP_FIN_WAIT2 all buffered data sent, waiting for remote
* to shutdown
*
* TCP_CLOSING both sides have shutdown but we still have
* data we have to finish sending
*
* TCP_TIME_WAIT timeout to catch resent junk before entering
* closed, can only be entered from FIN_WAIT2
* or CLOSING. Required because the other end
* may not have gotten our last ACK causing it
* to retransmit the data packet (which we ignore)
*
* TCP_CLOSE_WAIT remote side has shutdown and is waiting for
* us to finish writing our data and to shutdown
* (we have to close() to move on to LAST_ACK)
*
* TCP_LAST_ACK out side has shutdown after remote has
* shutdown. There may still be data in our
* buffer that we have to finish sending
*
* TCP_CLOSE socket is finished
*/
#include <linux/config.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/smp_lock.h>
#include <linux/fs.h>
#include <linux/random.h>
#include <linux/bootmem.h>
#include <linux/cache.h>
#include <net/icmp.h>
#include <net/tcp.h>
#include <net/xfrm.h>
#include <net/ip.h>
#include <asm/uaccess.h>
#include <asm/ioctls.h>
int sysctl_tcp_fin_timeout = TCP_FIN_TIMEOUT;
DEFINE_SNMP_STAT(struct tcp_mib, tcp_statistics) __read_mostly;
atomic_t tcp_orphan_count = ATOMIC_INIT(0);
EXPORT_SYMBOL_GPL(tcp_orphan_count);
int sysctl_tcp_mem[3] __read_mostly;
int sysctl_tcp_wmem[3] __read_mostly;
int sysctl_tcp_rmem[3] __read_mostly;
EXPORT_SYMBOL(sysctl_tcp_mem);
EXPORT_SYMBOL(sysctl_tcp_rmem);
EXPORT_SYMBOL(sysctl_tcp_wmem);
atomic_t tcp_memory_allocated; /* Current allocated memory. */
atomic_t tcp_sockets_allocated; /* Current number of TCP sockets. */
EXPORT_SYMBOL(tcp_memory_allocated);
EXPORT_SYMBOL(tcp_sockets_allocated);
/*
* Pressure flag: try to collapse.
* Technical note: it is used by multiple contexts non atomically.
* All the sk_stream_mem_schedule() is of this nature: accounting
* is strict, actions are advisory and have some latency.
*/
int tcp_memory_pressure;
EXPORT_SYMBOL(tcp_memory_pressure);
void tcp_enter_memory_pressure(void)
{
if (!tcp_memory_pressure) {
NET_INC_STATS(LINUX_MIB_TCPMEMORYPRESSURES);
tcp_memory_pressure = 1;
}
}
EXPORT_SYMBOL(tcp_enter_memory_pressure);
/*
* Wait for a TCP event.
*
* Note that we don't need to lock the socket, as the upper poll layers
* take care of normal races (between the test and the event) and we don't
* go look at any of the socket buffers directly.
*/
unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
{
unsigned int mask;
struct sock *sk = sock->sk;
struct tcp_sock *tp = tcp_sk(sk);
poll_wait(file, sk->sk_sleep, wait);
if (sk->sk_state == TCP_LISTEN)
return inet_csk_listen_poll(sk);
/* Socket is not locked. We are protected from async events
by poll logic and correct handling of state changes
made by another threads is impossible in any case.
*/
mask = 0;
if (sk->sk_err)
mask = POLLERR;
/*
* POLLHUP is certainly not done right. But poll() doesn't
* have a notion of HUP in just one direction, and for a
* socket the read side is more interesting.
*
* Some poll() documentation says that POLLHUP is incompatible
* with the POLLOUT/POLLWR flags, so somebody should check this
* all. But careful, it tends to be safer to return too many
* bits than too few, and you can easily break real applications
* if you don't tell them that something has hung up!
*
* Check-me.
*
* Check number 1. POLLHUP is _UNMASKABLE_ event (see UNIX98 and
* our fs/select.c). It means that after we received EOF,
* poll always returns immediately, making impossible poll() on write()
* in state CLOSE_WAIT. One solution is evident --- to set POLLHUP
* if and only if shutdown has been made in both directions.
* Actually, it is interesting to look how Solaris and DUX
* solve this dilemma. I would prefer, if PULLHUP were maskable,
* then we could set it on SND_SHUTDOWN. BTW examples given
* in Stevens' books assume exactly this behaviour, it explains
* why PULLHUP is incompatible with POLLOUT. --ANK
*
* NOTE. Check for TCP_CLOSE is added. The goal is to prevent
* blocking on fresh not-connected or disconnected socket. --ANK
*/
if (sk->sk_shutdown == SHUTDOWN_MASK || sk->sk_state == TCP_CLOSE)
mask |= POLLHUP;
if (sk->sk_shutdown & RCV_SHUTDOWN)
mask |= POLLIN | POLLRDNORM | POLLRDHUP;
/* Connected? */
if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV)) {
/* Potential race condition. If read of tp below will
* escape above sk->sk_state, we can be illegally awaken
* in SYN_* states. */
if ((tp->rcv_nxt != tp->copied_seq) &&
(tp->urg_seq != tp->copied_seq ||
tp->rcv_nxt != tp->copied_seq + 1 ||
sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data))
mask |= POLLIN | POLLRDNORM;
if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) {
mask |= POLLOUT | POLLWRNORM;
} else { /* send SIGIO later */
set_bit(SOCK_ASYNC_NOSPACE,
&sk->sk_socket->flags);
set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
/* Race breaker. If space is freed after
* wspace test but before the flags are set,
* IO signal will be lost.
*/
if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk))
mask |= POLLOUT | POLLWRNORM;
}
}
if (tp->urg_data & TCP_URG_VALID)
mask |= POLLPRI;
}
return mask;
}
int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
{
struct tcp_sock *tp = tcp_sk(sk);
int answ;
switch (cmd) {
case SIOCINQ:
if (sk->sk_state == TCP_LISTEN)
return -EINVAL;
lock_sock(sk);
if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
answ = 0;
else if (sock_flag(sk, SOCK_URGINLINE) ||
!tp->urg_data ||
before(tp->urg_seq, tp->copied_seq) ||
!before(tp->urg_seq, tp->rcv_nxt)) {
answ = tp->rcv_nxt - tp->copied_seq;
/* Subtract 1, if FIN is in queue. */
if (answ && !skb_queue_empty(&sk->sk_receive_queue))
answ -=
((struct sk_buff *)sk->sk_receive_queue.prev)->h.th->fin;
} else
answ = tp->urg_seq - tp->copied_seq;
release_sock(sk);
break;
case SIOCATMARK:
answ = tp->urg_data && tp->urg_seq == tp->copied_seq;
break;
case SIOCOUTQ:
if (sk->sk_state == TCP_LISTEN)
return -EINVAL;
if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
answ = 0;
else
answ = tp->write_seq - tp->snd_una;
break;
default:
return -ENOIOCTLCMD;
};
return put_user(answ, (int __user *)arg);
}
static inline void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb)
{
TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH;
tp->pushed_seq = tp->write_seq;
}
static inline int forced_push(struct tcp_sock *tp)
{
return after(tp->write_seq, tp->pushed_seq + (tp->max_window >> 1));
}
static inline void skb_entail(struct sock *sk, struct tcp_sock *tp,
struct sk_buff *skb)
{
skb->csum = 0;
TCP_SKB_CB(skb)->seq = tp->write_seq;
TCP_SKB_CB(skb)->end_seq = tp->write_seq;
TCP_SKB_CB(skb)->flags = TCPCB_FLAG_ACK;
TCP_SKB_CB(skb)->sacked = 0;
skb_header_release(skb);
__skb_queue_tail(&sk->sk_write_queue, skb);
sk_charge_skb(sk, skb);
if (!sk->sk_send_head)
sk->sk_send_head = skb;
if (tp->nonagle & TCP_NAGLE_PUSH)
tp->nonagle &= ~TCP_NAGLE_PUSH;
}
static inline void tcp_mark_urg(struct tcp_sock *tp, int flags,
struct sk_buff *skb)
{
if (flags & MSG_OOB) {
tp->urg_mode = 1;
tp->snd_up = tp->write_seq;
TCP_SKB_CB(skb)->sacked |= TCPCB_URG;
}
}
static inline void tcp_push(struct sock *sk, struct tcp_sock *tp, int flags,
int mss_now, int nonagle)
{
if (sk->sk_send_head) {
struct sk_buff *skb = sk->sk_write_queue.prev;
if (!(flags & MSG_MORE) || forced_push(tp))
tcp_mark_push(tp, skb);
tcp_mark_urg(tp, flags, skb);
__tcp_push_pending_frames(sk, tp, mss_now,
(flags & MSG_MORE) ? TCP_NAGLE_CORK : nonagle);
}
}
static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffset,
size_t psize, int flags)
{
struct tcp_sock *tp = tcp_sk(sk);
int mss_now, size_goal;
int err;
ssize_t copied;
long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
/* Wait for a connection to finish. */
if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
goto out_err;
clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
size_goal = tp->xmit_size_goal;
copied = 0;
err = -EPIPE;
if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
goto do_error;
while (psize > 0) {
struct sk_buff *skb = sk->sk_write_queue.prev;
struct page *page = pages[poffset / PAGE_SIZE];
int copy, i, can_coalesce;
int offset = poffset % PAGE_SIZE;
int size = min_t(size_t, psize, PAGE_SIZE - offset);
if (!sk->sk_send_head || (copy = size_goal - skb->len) <= 0) {
new_segment:
if (!sk_stream_memory_free(sk))
goto wait_for_sndbuf;
skb = sk_stream_alloc_pskb(sk, 0, 0,
sk->sk_allocation);
if (!skb)
goto wait_for_memory;
skb_entail(sk, tp, skb);
copy = size_goal;
}
if (copy > size)
copy = size;
i = skb_shinfo(skb)->nr_frags;
can_coalesce = skb_can_coalesce(skb, i, page, offset);
if (!can_coalesce && i >= MAX_SKB_FRAGS) {
tcp_mark_push(tp, skb);
goto new_segment;
}
if (!sk_stream_wmem_schedule(sk, copy))
goto wait_for_memory;
if (can_coalesce) {
skb_shinfo(skb)->frags[i - 1].size += copy;
} else {
get_page(page);
skb_fill_page_desc(skb, i, page, offset, copy);
}
skb->len += copy;
skb->data_len += copy;
skb->truesize += copy;
sk->sk_wmem_queued += copy;
sk->sk_forward_alloc -= copy;
skb->ip_summed = CHECKSUM_HW;
tp->write_seq += copy;
TCP_SKB_CB(skb)->end_seq += copy;
skb_shinfo(skb)->tso_segs = 0;
if (!copied)
TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_PSH;
copied += copy;
poffset += copy;
if (!(psize -= copy))
goto out;
if (skb->len < mss_now || (flags & MSG_OOB))
continue;
if (forced_push(tp)) {
tcp_mark_push(tp, skb);
__tcp_push_pending_frames(sk, tp, mss_now, TCP_NAGLE_PUSH);
} else if (skb == sk->sk_send_head)
tcp_push_one(sk, mss_now);
continue;
wait_for_sndbuf:
set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
wait_for_memory:
if (copied)
tcp_push(sk, tp, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
goto do_error;
mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
size_goal = tp->xmit_size_goal;
}
out:
if (copied)
tcp_push(sk, tp, flags, mss_now, tp->nonagle);
return copied;
do_error:
if (copied)
goto out;
out_err:
return sk_stream_error(sk, flags, err);
}
ssize_t tcp_sendpage(struct socket *sock, struct page *page, int offset,
size_t size, int flags)
{
ssize_t res;
struct sock *sk = sock->sk;
#define TCP_ZC_CSUM_FLAGS (NETIF_F_IP_CSUM | NETIF_F_NO_CSUM | NETIF_F_HW_CSUM)
if (!(sk->sk_route_caps & NETIF_F_SG) ||
!(sk->sk_route_caps & TCP_ZC_CSUM_FLAGS))
return sock_no_sendpage(sock, page, offset, size, flags);
#undef TCP_ZC_CSUM_FLAGS
lock_sock(sk);
TCP_CHECK_TIMER(sk);
res = do_tcp_sendpages(sk, &page, offset, size, flags);
TCP_CHECK_TIMER(sk);
release_sock(sk);
return res;
}
#define TCP_PAGE(sk) (sk->sk_sndmsg_page)
#define TCP_OFF(sk) (sk->sk_sndmsg_off)
static inline int select_size(struct sock *sk, struct tcp_sock *tp)
{
int tmp = tp->mss_cache;
if (sk->sk_route_caps & NETIF_F_SG) {
if (sk->sk_route_caps & NETIF_F_TSO)
tmp = 0;
else {
int pgbreak = SKB_MAX_HEAD(MAX_TCP_HEADER);
if (tmp >= pgbreak &&
tmp <= pgbreak + (MAX_SKB_FRAGS - 1) * PAGE_SIZE)
tmp = pgbreak;
}
}
return tmp;
}
int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
size_t size)
{
struct iovec *iov;
struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *skb;
int iovlen, flags;
int mss_now, size_goal;
int err, copied;
long timeo;
lock_sock(sk);
TCP_CHECK_TIMER(sk);
flags = msg->msg_flags;
timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
/* Wait for a connection to finish. */
if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
goto out_err;
/* This should be in poll */
clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
size_goal = tp->xmit_size_goal;
/* Ok commence sending. */
iovlen = msg->msg_iovlen;
iov = msg->msg_iov;
copied = 0;
err = -EPIPE;
if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
goto do_error;
while (--iovlen >= 0) {
int seglen = iov->iov_len;
unsigned char __user *from = iov->iov_base;
iov++;
while (seglen > 0) {
int copy;
skb = sk->sk_write_queue.prev;
if (!sk->sk_send_head ||
(copy = size_goal - skb->len) <= 0) {
new_segment:
/* Allocate new segment. If the interface is SG,
* allocate skb fitting to single page.
*/
if (!sk_stream_memory_free(sk))
goto wait_for_sndbuf;
skb = sk_stream_alloc_pskb(sk, select_size(sk, tp),
0, sk->sk_allocation);
if (!skb)
goto wait_for_memory;
/*
* Check whether we can use HW checksum.
*/
if (sk->sk_route_caps &
(NETIF_F_IP_CSUM | NETIF_F_NO_CSUM |
NETIF_F_HW_CSUM))
skb->ip_summed = CHECKSUM_HW;
skb_entail(sk, tp, skb);
copy = size_goal;
}
/* Try to append data to the end of skb. */
if (copy > seglen)
copy = seglen;
/* Where to copy to? */
if (skb_tailroom(skb) > 0) {
/* We have some space in skb head. Superb! */
if (copy > skb_tailroom(skb))
copy = skb_tailroom(skb);
if ((err = skb_add_data(skb, from, copy)) != 0)
goto do_fault;
} else {
int merge = 0;
int i = skb_shinfo(skb)->nr_frags;
struct page *page = TCP_PAGE(sk);
int off = TCP_OFF(sk);
if (skb_can_coalesce(skb, i, page, off) &&
off != PAGE_SIZE) {
/* We can extend the last page
* fragment. */
merge = 1;
} else if (i == MAX_SKB_FRAGS ||
(!i &&
!(sk->sk_route_caps & NETIF_F_SG))) {
/* Need to add new fragment and cannot
* do this because interface is non-SG,
* or because all the page slots are
* busy. */
tcp_mark_push(tp, skb);
goto new_segment;
} else if (page) {
if (off == PAGE_SIZE) {
put_page(page);
TCP_PAGE(sk) = page = NULL;
off = 0;
}
} else
off = 0;
if (copy > PAGE_SIZE - off)
copy = PAGE_SIZE - off;
if (!sk_stream_wmem_schedule(sk, copy))
goto wait_for_memory;
if (!page) {
/* Allocate new cache page. */
if (!(page = sk_stream_alloc_page(sk)))
goto wait_for_memory;
}
/* Time to copy data. We are close to
* the end! */
err = skb_copy_to_page(sk, from, skb, page,
off, copy);
if (err) {
/* If this page was new, give it to the
* socket so it does not get leaked.
*/
if (!TCP_PAGE(sk)) {
TCP_PAGE(sk) = page;
TCP_OFF(sk) = 0;
}
goto do_error;
}
/* Update the skb. */
if (merge) {
skb_shinfo(skb)->frags[i - 1].size +=
copy;
} else {
skb_fill_page_desc(skb, i, page, off, copy);
if (TCP_PAGE(sk)) {
get_page(page);
} else if (off + copy < PAGE_SIZE) {
get_page(page);
TCP_PAGE(sk) = page;
}
}
TCP_OFF(sk) = off + copy;
}
if (!copied)
TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_PSH;
tp->write_seq += copy;
TCP_SKB_CB(skb)->end_seq += copy;
skb_shinfo(skb)->tso_segs = 0;
from += copy;
copied += copy;
if ((seglen -= copy) == 0 && iovlen == 0)
goto out;
if (skb->len < mss_now || (flags & MSG_OOB))
continue;
if (forced_push(tp)) {
tcp_mark_push(tp, skb);
__tcp_push_pending_frames(sk, tp, mss_now, TCP_NAGLE_PUSH);
} else if (skb == sk->sk_send_head)
tcp_push_one(sk, mss_now);
continue;
wait_for_sndbuf:
set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
wait_for_memory:
if (copied)
tcp_push(sk, tp, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
goto do_error;
mss_now = tcp_current_mss(sk, !(flags&MSG_OOB));
size_goal = tp->xmit_size_goal;
}
}
out:
if (copied)
tcp_push(sk, tp, flags, mss_now, tp->nonagle);
TCP_CHECK_TIMER(sk);
release_sock(sk);
return copied;
do_fault:
if (!skb->len) {
if (sk->sk_send_head == skb)
sk->sk_send_head = NULL;
__skb_unlink(skb, &sk->sk_write_queue);
sk_stream_free_skb(sk, skb);
}
do_error:
if (copied)
goto out;
out_err:
err = sk_stream_error(sk, flags, err);
TCP_CHECK_TIMER(sk);
release_sock(sk);
return err;
}
/*
* Handle reading urgent data. BSD has very simple semantics for
* this, no blocking and very strange errors 8)
*/
static int tcp_recv_urg(struct sock *sk, long timeo,
struct msghdr *msg, int len, int flags,
int *addr_len)
{
struct tcp_sock *tp = tcp_sk(sk);
/* No URG data to read. */
if (sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data ||
tp->urg_data == TCP_URG_READ)
return -EINVAL; /* Yes this is right ! */
if (sk->sk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DONE))
return -ENOTCONN;
if (tp->urg_data & TCP_URG_VALID) {
int err = 0;
char c = tp->urg_data;
if (!(flags & MSG_PEEK))
tp->urg_data = TCP_URG_READ;
/* Read urgent data. */
msg->msg_flags |= MSG_OOB;
if (len > 0) {
if (!(flags & MSG_TRUNC))
err = memcpy_toiovec(msg->msg_iov, &c, 1);
len = 1;
} else
msg->msg_flags |= MSG_TRUNC;
return err ? -EFAULT : len;
}
if (sk->sk_state == TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN))
return 0;
/* Fixed the recv(..., MSG_OOB) behaviour. BSD docs and
* the available implementations agree in this case:
* this call should never block, independent of the
* blocking state of the socket.
* Mike <pall@rz.uni-karlsruhe.de>
*/
return -EAGAIN;
}
/* Clean up the receive buffer for full frames taken by the user,
* then send an ACK if necessary. COPIED is the number of bytes
* tcp_recvmsg has given to the user so far, it speeds up the
* calculation of whether or not we must ACK for the sake of
* a window update.
*/
static void cleanup_rbuf(struct sock *sk, int copied)
{
struct tcp_sock *tp = tcp_sk(sk);
int time_to_ack = 0;
#if TCP_DEBUG
struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
BUG_TRAP(!skb || before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq));
#endif
if (inet_csk_ack_scheduled(sk)) {
const struct inet_connection_sock *icsk = inet_csk(sk);
/* Delayed ACKs frequently hit locked sockets during bulk
* receive. */
if (icsk->icsk_ack.blocked ||
/* Once-per-two-segments ACK was not sent by tcp_input.c */
tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss ||
/*
* If this read emptied read buffer, we send ACK, if
* connection is not bidirectional, user drained
* receive buffer and there was a small segment
* in queue.
*/
(copied > 0 && (icsk->icsk_ack.pending & ICSK_ACK_PUSHED) &&
!icsk->icsk_ack.pingpong && !atomic_read(&sk->sk_rmem_alloc)))
time_to_ack = 1;
}
/* We send an ACK if we can now advertise a non-zero window
* which has been raised "significantly".
*
* Even if window raised up to infinity, do not send window open ACK
* in states, where we will not receive more. It is useless.
*/
if (copied > 0 && !time_to_ack && !(sk->sk_shutdown & RCV_SHUTDOWN)) {
__u32 rcv_window_now = tcp_receive_window(tp);
/* Optimize, __tcp_select_window() is not cheap. */
if (2*rcv_window_now <= tp->window_clamp) {
__u32 new_window = __tcp_select_window(sk);
/* Send ACK now, if this read freed lots of space
* in our buffer. Certainly, new_window is new window.
* We can advertise it now, if it is not less than current one.
* "Lots" means "at least twice" here.
*/
if (new_window && new_window >= 2 * rcv_window_now)
time_to_ack = 1;
}
}
if (time_to_ack)
tcp_send_ack(sk);
}
static void tcp_prequeue_process(struct sock *sk)
{
struct sk_buff *skb;
struct tcp_sock *tp = tcp_sk(sk);
NET_INC_STATS_USER(LINUX_MIB_TCPPREQUEUED);
/* RX process wants to run with disabled BHs, though it is not
* necessary */
local_bh_disable();
while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL)
sk->sk_backlog_rcv(sk, skb);
local_bh_enable();
/* Clear memory counter. */
tp->ucopy.memory = 0;
}
static inline struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
{
struct sk_buff *skb;
u32 offset;
skb_queue_walk(&sk->sk_receive_queue, skb) {
offset = seq - TCP_SKB_CB(skb)->seq;
if (skb->h.th->syn)
offset--;
if (offset < skb->len || skb->h.th->fin) {
*off = offset;
return skb;
}
}
return NULL;
}
/*
* This routine provides an alternative to tcp_recvmsg() for routines
* that would like to handle copying from skbuffs directly in 'sendfile'
* fashion.
* Note:
* - It is assumed that the socket was locked by the caller.
* - The routine does not block.
* - At present, there is no support for reading OOB data
* or for 'peeking' the socket using this routine
* (although both would be easy to implement).
*/
int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
sk_read_actor_t recv_actor)
{
struct sk_buff *skb;
struct tcp_sock *tp = tcp_sk(sk);
u32 seq = tp->copied_seq;
u32 offset;
int copied = 0;
if (sk->sk_state == TCP_LISTEN)
return -ENOTCONN;
while ((skb = tcp_recv_skb(sk, seq, &offset)) != NULL) {
if (offset < skb->len) {
size_t used, len;
len = skb->len - offset;
/* Stop reading if we hit a patch of urgent data */
if (tp->urg_data) {
u32 urg_offset = tp->urg_seq - seq;
if (urg_offset < len)
len = urg_offset;
if (!len)
break;
}
used = recv_actor(desc, skb, offset, len);
if (used <= len) {
seq += used;
copied += used;
offset += used;
}
if (offset != skb->len)
break;
}
if (skb->h.th->fin) {
sk_eat_skb(sk, skb);
++seq;
break;
}
sk_eat_skb(sk, skb);
if (!desc->count)
break;
}
tp->copied_seq = seq;
tcp_rcv_space_adjust(sk);
/* Clean up data we have read: This will do ACK frames. */
if (copied)
cleanup_rbuf(sk, copied);
return copied;
}
/*
* This routine copies from a sock struct into the user buffer.
*
* Technical note: in 2.3 we work on _locked_ socket, so that
* tricks with *seq access order and skb->users are not required.
* Probably, code can be easily improved even more.
*/
int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
size_t len, int nonblock, int flags, int *addr_len)
{
struct tcp_sock *tp = tcp_sk(sk);
int copied = 0;
u32 peek_seq;
u32 *seq;
unsigned long used;
int err;
int target; /* Read at least this many bytes */
long timeo;
struct task_struct *user_recv = NULL;
lock_sock(sk);
TCP_CHECK_TIMER(sk);
err = -ENOTCONN;
if (sk->sk_state == TCP_LISTEN)
goto out;
timeo = sock_rcvtimeo(sk, nonblock);
/* Urgent data needs to be handled specially. */
if (flags & MSG_OOB)
goto recv_urg;
seq = &tp->copied_seq;
if (flags & MSG_PEEK) {
peek_seq = tp->copied_seq;
seq = &peek_seq;
}
target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
do {
struct sk_buff *skb;
u32 offset;
/* Are we at urgent data? Stop if we have read anything or have SIGURG pending. */
if (tp->urg_data && tp->urg_seq == *seq) {
if (copied)
break;
if (signal_pending(current)) {
copied = timeo ? sock_intr_errno(timeo) : -EAGAIN;
break;
}
}
/* Next get a buffer. */
skb = skb_peek(&sk->sk_receive_queue);
do {
if (!skb)
break;
/* Now that we have two receive queues this
* shouldn't happen.
*/
if (before(*seq, TCP_SKB_CB(skb)->seq)) {
printk(KERN_INFO "recvmsg bug: copied %X "
"seq %X\n", *seq, TCP_SKB_CB(skb)->seq);
break;
}
offset = *seq - TCP_SKB_CB(skb)->seq;
if (skb->h.th->syn)
offset--;
if (offset < skb->len)
goto found_ok_skb;
if (skb->h.th->fin)
goto found_fin_ok;
BUG_TRAP(flags & MSG_PEEK);
skb = skb->next;
} while (skb != (struct sk_buff *)&sk->sk_receive_queue);
/* Well, if we have backlog, try to process it now yet. */
if (copied >= target && !sk->sk_backlog.tail)
break;
if (copied) {
if (sk->sk_err ||
sk->sk_state == TCP_CLOSE ||
(sk->sk_shutdown & RCV_SHUTDOWN) ||
!timeo ||
signal_pending(current) ||
(flags & MSG_PEEK))
break;
} else {
if (sock_flag(sk, SOCK_DONE))
break;
if (sk->sk_err) {
copied = sock_error(sk);
break;
}
if (sk->sk_shutdown & RCV_SHUTDOWN)
break;
if (sk->sk_state == TCP_CLOSE) {
if (!sock_flag(sk, SOCK_DONE)) {
/* This occurs when user tries to read
* from never connected socket.
*/
copied = -ENOTCONN;
break;
}
break;
}
if (!timeo) {
copied = -EAGAIN;
break;
}
if (signal_pending(current)) {
copied = sock_intr_errno(timeo);
break;
}
}
cleanup_rbuf(sk, copied);
if (!sysctl_tcp_low_latency && tp->ucopy.task == user_recv) {
/* Install new reader */
if (!user_recv && !(flags & (MSG_TRUNC | MSG_PEEK))) {
user_recv = current;
tp->ucopy.task = user_recv;
tp->ucopy.iov = msg->msg_iov;
}
tp->ucopy.len = len;
BUG_TRAP(tp->copied_seq == tp->rcv_nxt ||
(flags & (MSG_PEEK | MSG_TRUNC)));
/* Ugly... If prequeue is not empty, we have to
* process it before releasing socket, otherwise
* order will be broken at second iteration.
* More elegant solution is required!!!
*
* Look: we have the following (pseudo)queues:
*
* 1. packets in flight
* 2. backlog
* 3. prequeue
* 4. receive_queue
*
* Each queue can be processed only if the next ones
* are empty. At this point we have empty receive_queue.
* But prequeue _can_ be not empty after 2nd iteration,
* when we jumped to start of loop because backlog
* processing added something to receive_queue.
* We cannot release_sock(), because backlog contains
* packets arrived _after_ prequeued ones.
*
* Shortly, algorithm is clear --- to process all
* the queues in order. We could make it more directly,
* requeueing packets from backlog to prequeue, if
* is not empty. It is more elegant, but eats cycles,
* unfortunately.
*/
if (!skb_queue_empty(&tp->ucopy.prequeue))
goto do_prequeue;
/* __ Set realtime policy in scheduler __ */
}
if (copied >= target) {
/* Do not sleep, just process backlog. */
release_sock(sk);
lock_sock(sk);
} else
sk_wait_data(sk, &timeo);
if (user_recv) {
int chunk;
/* __ Restore normal policy in scheduler __ */
if ((chunk = len - tp->ucopy.len) != 0) {
NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMBACKLOG, chunk);
len -= chunk;
copied += chunk;
}
if (tp->rcv_nxt == tp->copied_seq &&
!skb_queue_empty(&tp->ucopy.prequeue)) {
do_prequeue:
tcp_prequeue_process(sk);
if ((chunk = len - tp->ucopy.len) != 0) {
NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
len -= chunk;
copied += chunk;
}
}
}
if ((flags & MSG_PEEK) && peek_seq != tp->copied_seq) {
if (net_ratelimit())
printk(KERN_DEBUG "TCP(%s:%d): Application bug, race in MSG_PEEK.\n",
current->comm, current->pid);
peek_seq = tp->copied_seq;
}
continue;
found_ok_skb:
/* Ok so how much can we use? */
used = skb->len - offset;
if (len < used)
used = len;
/* Do we have urgent data here? */
if (tp->urg_data) {
u32 urg_offset = tp->urg_seq - *seq;
if (urg_offset < used) {
if (!urg_offset) {
if (!sock_flag(sk, SOCK_URGINLINE)) {
++*seq;
offset++;
used--;
if (!used)
goto skip_copy;
}
} else
used = urg_offset;
}
}
if (!(flags & MSG_TRUNC)) {
err = skb_copy_datagram_iovec(skb, offset,
msg->msg_iov, used);
if (err) {
/* Exception. Bailout! */
if (!copied)
copied = -EFAULT;
break;
}
}
*seq += used;
copied += used;
len -= used;
tcp_rcv_space_adjust(sk);
skip_copy:
if (tp->urg_data && after(tp->copied_seq, tp->urg_seq)) {
tp->urg_data = 0;
tcp_fast_path_check(sk, tp);
}
if (used + offset < skb->len)
continue;
if (skb->h.th->fin)
goto found_fin_ok;
if (!(flags & MSG_PEEK))
sk_eat_skb(sk, skb);
continue;
found_fin_ok:
/* Process the FIN. */
++*seq;
if (!(flags & MSG_PEEK))
sk_eat_skb(sk, skb);
break;
} while (len > 0);
if (user_recv) {
if (!skb_queue_empty(&tp->ucopy.prequeue)) {
int chunk;
tp->ucopy.len = copied > 0 ? len : 0;
tcp_prequeue_process(sk);
if (copied > 0 && (chunk = len - tp->ucopy.len) != 0) {
NET_ADD_STATS_USER(LINUX_MIB_TCPDIRECTCOPYFROMPREQUEUE, chunk);
len -= chunk;
copied += chunk;
}
}
tp->ucopy.task = NULL;
tp->ucopy.len = 0;
}
/* According to UNIX98, msg_name/msg_namelen are ignored
* on connected socket. I was just happy when found this 8) --ANK
*/
/* Clean up data we have read: This will do ACK frames. */
cleanup_rbuf(sk, copied);
TCP_CHECK_TIMER(sk);
release_sock(sk);
return copied;
out:
TCP_CHECK_TIMER(sk);
release_sock(sk);
return err;
recv_urg:
err = tcp_recv_urg(sk, timeo, msg, len, flags, addr_len);
goto out;
}
/*
* State processing on a close. This implements the state shift for
* sending our FIN frame. Note that we only send a FIN for some
* states. A shutdown() may have already sent the FIN, or we may be
* closed.
*/
static const unsigned char new_state[16] = {
/* current state: new state: action: */
/* (Invalid) */ TCP_CLOSE,
/* TCP_ESTABLISHED */ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
/* TCP_SYN_SENT */ TCP_CLOSE,
/* TCP_SYN_RECV */ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
/* TCP_FIN_WAIT1 */ TCP_FIN_WAIT1,
/* TCP_FIN_WAIT2 */ TCP_FIN_WAIT2,
/* TCP_TIME_WAIT */ TCP_CLOSE,
/* TCP_CLOSE */ TCP_CLOSE,
/* TCP_CLOSE_WAIT */ TCP_LAST_ACK | TCP_ACTION_FIN,
/* TCP_LAST_ACK */ TCP_LAST_ACK,
/* TCP_LISTEN */ TCP_CLOSE,
/* TCP_CLOSING */ TCP_CLOSING,
};
static int tcp_close_state(struct sock *sk)
{
int next = (int)new_state[sk->sk_state];
int ns = next & TCP_STATE_MASK;
tcp_set_state(sk, ns);
return next & TCP_ACTION_FIN;
}
/*
* Shutdown the sending side of a connection. Much like close except
* that we don't receive shut down or set_sock_flag(sk, SOCK_DEAD).
*/
void tcp_shutdown(struct sock *sk, int how)
{
/* We need to grab some memory, and put together a FIN,
* and then put it into the queue to be sent.
* Tim MacKenzie(tym@dibbler.cs.monash.edu.au) 4 Dec '92.
*/
if (!(how & SEND_SHUTDOWN))
return;
/* If we've already sent a FIN, or it's a closed state, skip this. */
if ((1 << sk->sk_state) &
(TCPF_ESTABLISHED | TCPF_SYN_SENT |
TCPF_SYN_RECV | TCPF_CLOSE_WAIT)) {
/* Clear out any half completed packets. FIN if needed. */
if (tcp_close_state(sk))
tcp_send_fin(sk);
}
}
void tcp_close(struct sock *sk, long timeout)
{
struct sk_buff *skb;
int data_was_unread = 0;
int state;
lock_sock(sk);
sk->sk_shutdown = SHUTDOWN_MASK;
if (sk->sk_state == TCP_LISTEN) {
tcp_set_state(sk, TCP_CLOSE);
/* Special case. */
inet_csk_listen_stop(sk);
goto adjudge_to_death;
}
/* We need to flush the recv. buffs. We do this only on the
* descriptor close, not protocol-sourced closes, because the
* reader process may not have drained the data yet!
*/
while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq -
skb->h.th->fin;
data_was_unread += len;
__kfree_skb(skb);
}
sk_stream_mem_reclaim(sk);
/* As outlined in draft-ietf-tcpimpl-prob-03.txt, section
* 3.10, we send a RST here because data was lost. To
* witness the awful effects of the old behavior of always
* doing a FIN, run an older 2.1.x kernel or 2.0.x, start
* a bulk GET in an FTP client, suspend the process, wait
* for the client to advertise a zero window, then kill -9
* the FTP client, wheee... Note: timeout is always zero
* in such a case.
*/
if (data_was_unread) {
/* Unread data was tossed, zap the connection. */
NET_INC_STATS_USER(LINUX_MIB_TCPABORTONCLOSE);
tcp_set_state(sk, TCP_CLOSE);
tcp_send_active_reset(sk, GFP_KERNEL);
} else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
/* Check zero linger _after_ checking for unread data. */
sk->sk_prot->disconnect(sk, 0);
NET_INC_STATS_USER(LINUX_MIB_TCPABORTONDATA);
} else if (tcp_close_state(sk)) {
/* We FIN if the application ate all the data before
* zapping the connection.
*/
/* RED-PEN. Formally speaking, we have broken TCP state
* machine. State transitions:
*
* TCP_ESTABLISHED -> TCP_FIN_WAIT1
* TCP_SYN_RECV -> TCP_FIN_WAIT1 (forget it, it's impossible)
* TCP_CLOSE_WAIT -> TCP_LAST_ACK
*
* are legal only when FIN has been sent (i.e. in window),
* rather than queued out of window. Purists blame.
*
* F.e. "RFC state" is ESTABLISHED,
* if Linux state is FIN-WAIT-1, but FIN is still not sent.
*
* The visible declinations are that sometimes
* we enter time-wait state, when it is not required really
* (harmless), do not send active resets, when they are
* required by specs (TCP_ESTABLISHED, TCP_CLOSE_WAIT, when
* they look as CLOSING or LAST_ACK for Linux)
* Probably, I missed some more holelets.
* --ANK
*/
tcp_send_fin(sk);
}
sk_stream_wait_close(sk, timeout);
adjudge_to_death:
state = sk->sk_state;
sock_hold(sk);
sock_orphan(sk);
atomic_inc(sk->sk_prot->orphan_count);
/* It is the last release_sock in its life. It will remove backlog. */
release_sock(sk);
/* Now socket is owned by kernel and we acquire BH lock
to finish close. No need to check for user refs.
*/
local_bh_disable();
bh_lock_sock(sk);
BUG_TRAP(!sock_owned_by_user(sk));
/* Have we already been destroyed by a softirq or backlog? */
if (state != TCP_CLOSE && sk->sk_state == TCP_CLOSE)
goto out;
/* This is a (useful) BSD violating of the RFC. There is a
* problem with TCP as specified in that the other end could
* keep a socket open forever with no application left this end.
* We use a 3 minute timeout (about the same as BSD) then kill
* our end. If they send after that then tough - BUT: long enough
* that we won't make the old 4*rto = almost no time - whoops
* reset mistake.
*
* Nope, it was not mistake. It is really desired behaviour
* f.e. on http servers, when such sockets are useless, but
* consume significant resources. Let's do it with special
* linger2 option. --ANK
*/
if (sk->sk_state == TCP_FIN_WAIT2) {
struct tcp_sock *tp = tcp_sk(sk);
if (tp->linger2 < 0) {
tcp_set_state(sk, TCP_CLOSE);
tcp_send_active_reset(sk, GFP_ATOMIC);
NET_INC_STATS_BH(LINUX_MIB_TCPABORTONLINGER);
} else {
const int tmo = tcp_fin_time(sk);
if (tmo > TCP_TIMEWAIT_LEN) {
inet_csk_reset_keepalive_timer(sk, tcp_fin_time(sk));
} else {
tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
goto out;
}
}
}
if (sk->sk_state != TCP_CLOSE) {
sk_stream_mem_reclaim(sk);
if (atomic_read(sk->sk_prot->orphan_count) > sysctl_tcp_max_orphans ||
(sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
atomic_read(&tcp_memory_allocated) > sysctl_tcp_mem[2])) {
if (net_ratelimit())
printk(KERN_INFO "TCP: too many of orphaned "
"sockets\n");
tcp_set_state(sk, TCP_CLOSE);
tcp_send_active_reset(sk, GFP_ATOMIC);
NET_INC_STATS_BH(LINUX_MIB_TCPABORTONMEMORY);
}
}
if (sk->sk_state == TCP_CLOSE)
inet_csk_destroy_sock(sk);
/* Otherwise, socket is reprieved until protocol close. */
out:
bh_unlock_sock(sk);
local_bh_enable();
sock_put(sk);
}
/* These states need RST on ABORT according to RFC793 */
static inline int tcp_need_reset(int state)
{
return (1 << state) &
(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_FIN_WAIT1 |
TCPF_FIN_WAIT2 | TCPF_SYN_RECV);
}
int tcp_disconnect(struct sock *sk, int flags)
{
struct inet_sock *inet = inet_sk(sk);
struct inet_connection_sock *icsk = inet_csk(sk);
struct tcp_sock *tp = tcp_sk(sk);
int err = 0;
int old_state = sk->sk_state;
if (old_state != TCP_CLOSE)
tcp_set_state(sk, TCP_CLOSE);
/* ABORT function of RFC793 */
if (old_state == TCP_LISTEN) {
inet_csk_listen_stop(sk);
} else if (tcp_need_reset(old_state) ||
(tp->snd_nxt != tp->write_seq &&
(1 << old_state) & (TCPF_CLOSING | TCPF_LAST_ACK))) {
/* The last check adjusts for discrepancy of Linux wrt. RFC
* states
*/
tcp_send_active_reset(sk, gfp_any());
sk->sk_err = ECONNRESET;
} else if (old_state == TCP_SYN_SENT)
sk->sk_err = ECONNRESET;
tcp_clear_xmit_timers(sk);
__skb_queue_purge(&sk->sk_receive_queue);
sk_stream_writequeue_purge(sk);
__skb_queue_purge(&tp->out_of_order_queue);
inet->dport = 0;
if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
inet_reset_saddr(sk);
sk->sk_shutdown = 0;
sock_reset_flag(sk, SOCK_DONE);
tp->srtt = 0;
if ((tp->write_seq += tp->max_window + 2) == 0)
tp->write_seq = 1;
icsk->icsk_backoff = 0;
tp->snd_cwnd = 2;
icsk->icsk_probes_out = 0;
tp->packets_out = 0;
tp->snd_ssthresh = 0x7fffffff;
tp->snd_cwnd_cnt = 0;
tp->bytes_acked = 0;
tcp_set_ca_state(sk, TCP_CA_Open);
tcp_clear_retrans(tp);
inet_csk_delack_init(sk);
sk->sk_send_head = NULL;
tp->rx_opt.saw_tstamp = 0;
tcp_sack_reset(&tp->rx_opt);
__sk_dst_reset(sk);
BUG_TRAP(!inet->num || icsk->icsk_bind_hash);
sk->sk_error_report(sk);
return err;
}
/*
* Socket option code for TCP.
*/
static int do_tcp_setsockopt(struct sock *sk, int level,
int optname, char __user *optval, int optlen)
{
struct tcp_sock *tp = tcp_sk(sk);
struct inet_connection_sock *icsk = inet_csk(sk);
int val;
int err = 0;
/* This is a string value all the others are int's */
if (optname == TCP_CONGESTION) {
char name[TCP_CA_NAME_MAX];
if (optlen < 1)
return -EINVAL;
val = strncpy_from_user(name, optval,
min(TCP_CA_NAME_MAX-1, optlen));
if (val < 0)
return -EFAULT;
name[val] = 0;
lock_sock(sk);
err = tcp_set_congestion_control(sk, name);
release_sock(sk);
return err;
}
if (optlen < sizeof(int))
return -EINVAL;
if (get_user(val, (int __user *)optval))
return -EFAULT;
lock_sock(sk);
switch (optname) {
case TCP_MAXSEG:
/* Values greater than interface MTU won't take effect. However
* at the point when this call is done we typically don't yet
* know which interface is going to be used */
if (val < 8 || val > MAX_TCP_WINDOW) {
err = -EINVAL;
break;
}
tp->rx_opt.user_mss = val;
break;
case TCP_NODELAY:
if (val) {
/* TCP_NODELAY is weaker than TCP_CORK, so that
* this option on corked socket is remembered, but
* it is not activated until cork is cleared.
*
* However, when TCP_NODELAY is set we make
* an explicit push, which overrides even TCP_CORK
* for currently queued segments.
*/
tp->nonagle |= TCP_NAGLE_OFF|TCP_NAGLE_PUSH;
tcp_push_pending_frames(sk, tp);
} else {
tp->nonagle &= ~TCP_NAGLE_OFF;
}
break;
case TCP_CORK:
/* When set indicates to always queue non-full frames.
* Later the user clears this option and we transmit
* any pending partial frames in the queue. This is
* meant to be used alongside sendfile() to get properly
* filled frames when the user (for example) must write
* out headers with a write() call first and then use
* sendfile to send out the data parts.
*
* TCP_CORK can be set together with TCP_NODELAY and it is
* stronger than TCP_NODELAY.
*/
if (val) {
tp->nonagle |= TCP_NAGLE_CORK;
} else {
tp->nonagle &= ~TCP_NAGLE_CORK;
if (tp->nonagle&TCP_NAGLE_OFF)
tp->nonagle |= TCP_NAGLE_PUSH;
tcp_push_pending_frames(sk, tp);
}
break;
case TCP_KEEPIDLE:
if (val < 1 || val > MAX_TCP_KEEPIDLE)
err = -EINVAL;
else {
tp->keepalive_time = val * HZ;
if (sock_flag(sk, SOCK_KEEPOPEN) &&
!((1 << sk->sk_state) &
(TCPF_CLOSE | TCPF_LISTEN))) {
__u32 elapsed = tcp_time_stamp - tp->rcv_tstamp;
if (tp->keepalive_time > elapsed)
elapsed = tp->keepalive_time - elapsed;
else
elapsed = 0;
inet_csk_reset_keepalive_timer(sk, elapsed);
}
}
break;
case TCP_KEEPINTVL:
if (val < 1 || val > MAX_TCP_KEEPINTVL)
err = -EINVAL;
else
tp->keepalive_intvl = val * HZ;
break;
case TCP_KEEPCNT:
if (val < 1 || val > MAX_TCP_KEEPCNT)
err = -EINVAL;
else
tp->keepalive_probes = val;
break;
case TCP_SYNCNT:
if (val < 1 || val > MAX_TCP_SYNCNT)
err = -EINVAL;
else
icsk->icsk_syn_retries = val;
break;
case TCP_LINGER2:
if (val < 0)
tp->linger2 = -1;
else if (val > sysctl_tcp_fin_timeout / HZ)
tp->linger2 = 0;
else
tp->linger2 = val * HZ;
break;
case TCP_DEFER_ACCEPT:
icsk->icsk_accept_queue.rskq_defer_accept = 0;
if (val > 0) {
/* Translate value in seconds to number of
* retransmits */
while (icsk->icsk_accept_queue.rskq_defer_accept < 32 &&
val > ((TCP_TIMEOUT_INIT / HZ) <<
icsk->icsk_accept_queue.rskq_defer_accept))
icsk->icsk_accept_queue.rskq_defer_accept++;
icsk->icsk_accept_queue.rskq_defer_accept++;
}
break;
case TCP_WINDOW_CLAMP:
if (!val) {
if (sk->sk_state != TCP_CLOSE) {
err = -EINVAL;
break;
}
tp->window_clamp = 0;
} else
tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ?
SOCK_MIN_RCVBUF / 2 : val;
break;
case TCP_QUICKACK:
if (!val) {
icsk->icsk_ack.pingpong = 1;
} else {
icsk->icsk_ack.pingpong = 0;
if ((1 << sk->sk_state) &
(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT) &&
inet_csk_ack_scheduled(sk)) {
icsk->icsk_ack.pending |= ICSK_ACK_PUSHED;
cleanup_rbuf(sk, 1);
if (!(val & 1))
icsk->icsk_ack.pingpong = 1;
}
}
break;
default:
err = -ENOPROTOOPT;
break;
};
release_sock(sk);
return err;
}
int tcp_setsockopt(struct sock *sk, int level, int optname, char __user *optval,
int optlen)
{
struct inet_connection_sock *icsk = inet_csk(sk);
if (level != SOL_TCP)
return icsk->icsk_af_ops->setsockopt(sk, level, optname,
optval, optlen);
return do_tcp_setsockopt(sk, level, optname, optval, optlen);
}
#ifdef CONFIG_COMPAT
int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
char __user *optval, int optlen)
{
if (level != SOL_TCP)
return inet_csk_compat_setsockopt(sk, level, optname,
optval, optlen);
return do_tcp_setsockopt(sk, level, optname, optval, optlen);
}
EXPORT_SYMBOL(compat_tcp_setsockopt);
#endif
/* Return information about state of tcp endpoint in API format. */
void tcp_get_info(struct sock *sk, struct tcp_info *info)
{
struct tcp_sock *tp = tcp_sk(sk);
const struct inet_connection_sock *icsk = inet_csk(sk);
u32 now = tcp_time_stamp;
memset(info, 0, sizeof(*info));
info->tcpi_state = sk->sk_state;
info->tcpi_ca_state = icsk->icsk_ca_state;
info->tcpi_retransmits = icsk->icsk_retransmits;
info->tcpi_probes = icsk->icsk_probes_out;
info->tcpi_backoff = icsk->icsk_backoff;
if (tp->rx_opt.tstamp_ok)
info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
if (tp->rx_opt.sack_ok)
info->tcpi_options |= TCPI_OPT_SACK;
if (tp->rx_opt.wscale_ok) {
info->tcpi_options |= TCPI_OPT_WSCALE;
info->tcpi_snd_wscale = tp->rx_opt.snd_wscale;
info->tcpi_rcv_wscale = tp->rx_opt.rcv_wscale;
}
if (tp->ecn_flags&TCP_ECN_OK)
info->tcpi_options |= TCPI_OPT_ECN;
info->tcpi_rto = jiffies_to_usecs(icsk->icsk_rto);
info->tcpi_ato = jiffies_to_usecs(icsk->icsk_ack.ato);
info->tcpi_snd_mss = tp->mss_cache;
info->tcpi_rcv_mss = icsk->icsk_ack.rcv_mss;
info->tcpi_unacked = tp->packets_out;
info->tcpi_sacked = tp->sacked_out;
info->tcpi_lost = tp->lost_out;
info->tcpi_retrans = tp->retrans_out;
info->tcpi_fackets = tp->fackets_out;
info->tcpi_last_data_sent = jiffies_to_msecs(now - tp->lsndtime);
info->tcpi_last_data_recv = jiffies_to_msecs(now - icsk->icsk_ack.lrcvtime);
info->tcpi_last_ack_recv = jiffies_to_msecs(now - tp->rcv_tstamp);
info->tcpi_pmtu = icsk->icsk_pmtu_cookie;
info->tcpi_rcv_ssthresh = tp->rcv_ssthresh;
info->tcpi_rtt = jiffies_to_usecs(tp->srtt)>>3;
info->tcpi_rttvar = jiffies_to_usecs(tp->mdev)>>2;
info->tcpi_snd_ssthresh = tp->snd_ssthresh;
info->tcpi_snd_cwnd = tp->snd_cwnd;
info->tcpi_advmss = tp->advmss;
info->tcpi_reordering = tp->reordering;
info->tcpi_rcv_rtt = jiffies_to_usecs(tp->rcv_rtt_est.rtt)>>3;
info->tcpi_rcv_space = tp->rcvq_space.space;
info->tcpi_total_retrans = tp->total_retrans;
}
EXPORT_SYMBOL_GPL(tcp_get_info);
static int do_tcp_getsockopt(struct sock *sk, int level,
int optname, char __user *optval, int __user *optlen)
{
struct inet_connection_sock *icsk = inet_csk(sk);
struct tcp_sock *tp = tcp_sk(sk);
int val, len;
if (get_user(len, optlen))
return -EFAULT;
len = min_t(unsigned int, len, sizeof(int));
if (len < 0)
return -EINVAL;
switch (optname) {
case TCP_MAXSEG:
val = tp->mss_cache;
if (!val && ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)))
val = tp->rx_opt.user_mss;
break;
case TCP_NODELAY:
val = !!(tp->nonagle&TCP_NAGLE_OFF);
break;
case TCP_CORK:
val = !!(tp->nonagle&TCP_NAGLE_CORK);
break;
case TCP_KEEPIDLE:
val = (tp->keepalive_time ? : sysctl_tcp_keepalive_time) / HZ;
break;
case TCP_KEEPINTVL:
val = (tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl) / HZ;
break;
case TCP_KEEPCNT:
val = tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
break;
case TCP_SYNCNT:
val = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries;
break;
case TCP_LINGER2:
val = tp->linger2;
if (val >= 0)
val = (val ? : sysctl_tcp_fin_timeout) / HZ;
break;
case TCP_DEFER_ACCEPT:
val = !icsk->icsk_accept_queue.rskq_defer_accept ? 0 :
((TCP_TIMEOUT_INIT / HZ) << (icsk->icsk_accept_queue.rskq_defer_accept - 1));
break;
case TCP_WINDOW_CLAMP:
val = tp->window_clamp;
break;
case TCP_INFO: {
struct tcp_info info;
if (get_user(len, optlen))
return -EFAULT;
tcp_get_info(sk, &info);
len = min_t(unsigned int, len, sizeof(info));
if (put_user(len, optlen))
return -EFAULT;
if (copy_to_user(optval, &info, len))
return -EFAULT;
return 0;
}
case TCP_QUICKACK:
val = !icsk->icsk_ack.pingpong;
break;
case TCP_CONGESTION:
if (get_user(len, optlen))
return -EFAULT;
len = min_t(unsigned int, len, TCP_CA_NAME_MAX);
if (put_user(len, optlen))
return -EFAULT;
if (copy_to_user(optval, icsk->icsk_ca_ops->name, len))
return -EFAULT;
return 0;
default:
return -ENOPROTOOPT;
};
if (put_user(len, optlen))
return -EFAULT;
if (copy_to_user(optval, &val, len))
return -EFAULT;
return 0;
}
int tcp_getsockopt(struct sock *sk, int level, int optname, char __user *optval,
int __user *optlen)
{
struct inet_connection_sock *icsk = inet_csk(sk);
if (level != SOL_TCP)
return icsk->icsk_af_ops->getsockopt(sk, level, optname,
optval, optlen);
return do_tcp_getsockopt(sk, level, optname, optval, optlen);
}
#ifdef CONFIG_COMPAT
int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
char __user *optval, int __user *optlen)
{
if (level != SOL_TCP)
return inet_csk_compat_getsockopt(sk, level, optname,
optval, optlen);
return do_tcp_getsockopt(sk, level, optname, optval, optlen);
}
EXPORT_SYMBOL(compat_tcp_getsockopt);
#endif
extern void __skb_cb_too_small_for_tcp(int, int);
extern struct tcp_congestion_ops tcp_reno;
static __initdata unsigned long thash_entries;
static int __init set_thash_entries(char *str)
{
if (!str)
return 0;
thash_entries = simple_strtoul(str, &str, 0);
return 1;
}
__setup("thash_entries=", set_thash_entries);
void __init tcp_init(void)
{
struct sk_buff *skb = NULL;
unsigned long limit;
int order, i, max_share;
if (sizeof(struct tcp_skb_cb) > sizeof(skb->cb))
__skb_cb_too_small_for_tcp(sizeof(struct tcp_skb_cb),
sizeof(skb->cb));
tcp_hashinfo.bind_bucket_cachep =
kmem_cache_create("tcp_bind_bucket",
sizeof(struct inet_bind_bucket), 0,
SLAB_HWCACHE_ALIGN, NULL, NULL);
if (!tcp_hashinfo.bind_bucket_cachep)
panic("tcp_init: Cannot alloc tcp_bind_bucket cache.");
/* Size and allocate the main established and bind bucket
* hash tables.
*
* The methodology is similar to that of the buffer cache.
*/
tcp_hashinfo.ehash =
alloc_large_system_hash("TCP established",
sizeof(struct inet_ehash_bucket),
thash_entries,
(num_physpages >= 128 * 1024) ?
13 : 15,
HASH_HIGHMEM,
&tcp_hashinfo.ehash_size,
NULL,
0);
tcp_hashinfo.ehash_size = (1 << tcp_hashinfo.ehash_size) >> 1;
for (i = 0; i < (tcp_hashinfo.ehash_size << 1); i++) {
rwlock_init(&tcp_hashinfo.ehash[i].lock);
INIT_HLIST_HEAD(&tcp_hashinfo.ehash[i].chain);
}
tcp_hashinfo.bhash =
alloc_large_system_hash("TCP bind",
sizeof(struct inet_bind_hashbucket),
tcp_hashinfo.ehash_size,
(num_physpages >= 128 * 1024) ?
13 : 15,
HASH_HIGHMEM,
&tcp_hashinfo.bhash_size,
NULL,
64 * 1024);
tcp_hashinfo.bhash_size = 1 << tcp_hashinfo.bhash_size;
for (i = 0; i < tcp_hashinfo.bhash_size; i++) {
spin_lock_init(&tcp_hashinfo.bhash[i].lock);
INIT_HLIST_HEAD(&tcp_hashinfo.bhash[i].chain);
}
/* Try to be a bit smarter and adjust defaults depending
* on available memory.
*/
for (order = 0; ((1 << order) << PAGE_SHIFT) <
(tcp_hashinfo.bhash_size * sizeof(struct inet_bind_hashbucket));
order++)
;
if (order >= 4) {
sysctl_local_port_range[0] = 32768;
sysctl_local_port_range[1] = 61000;
tcp_death_row.sysctl_max_tw_buckets = 180000;
sysctl_tcp_max_orphans = 4096 << (order - 4);
sysctl_max_syn_backlog = 1024;
} else if (order < 3) {
sysctl_local_port_range[0] = 1024 * (3 - order);
tcp_death_row.sysctl_max_tw_buckets >>= (3 - order);
sysctl_tcp_max_orphans >>= (3 - order);
sysctl_max_syn_backlog = 128;
}
sysctl_tcp_mem[0] = 768 << order;
sysctl_tcp_mem[1] = 1024 << order;
sysctl_tcp_mem[2] = 1536 << order;
limit = ((unsigned long)sysctl_tcp_mem[1]) << (PAGE_SHIFT - 7);
max_share = min(4UL*1024*1024, limit);
sysctl_tcp_wmem[0] = SK_STREAM_MEM_QUANTUM;
sysctl_tcp_wmem[1] = 16*1024;
sysctl_tcp_wmem[2] = max(64*1024, max_share);
sysctl_tcp_rmem[0] = SK_STREAM_MEM_QUANTUM;
sysctl_tcp_rmem[1] = 87380;
sysctl_tcp_rmem[2] = max(87380, max_share);
printk(KERN_INFO "TCP: Hash tables configured "
"(established %d bind %d)\n",
tcp_hashinfo.ehash_size << 1, tcp_hashinfo.bhash_size);
tcp_register_congestion_control(&tcp_reno);
}
EXPORT_SYMBOL(tcp_close);
EXPORT_SYMBOL(tcp_disconnect);
EXPORT_SYMBOL(tcp_getsockopt);
EXPORT_SYMBOL(tcp_ioctl);
EXPORT_SYMBOL(tcp_poll);
EXPORT_SYMBOL(tcp_read_sock);
EXPORT_SYMBOL(tcp_recvmsg);
EXPORT_SYMBOL(tcp_sendmsg);
EXPORT_SYMBOL(tcp_sendpage);
EXPORT_SYMBOL(tcp_setsockopt);
EXPORT_SYMBOL(tcp_shutdown);
EXPORT_SYMBOL(tcp_statistics);
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