This patch uses __copy_from_user_nocache on transmit to bypass data
cache for a performance improvement.  skb_add_data_nocache and
skb_copy_to_page_nocache can be called by sendmsg functions to use
this feature, initial support is in tcp_sendmsg.  This functionality is
configurable per device using ethtool.

Presumably, this feature would only be useful when the driver does
not touch the data.  The feature is turned on by default if a device
indicates that it does some form of checksum offload; it is off by
default for devices that do no checksum offload or indicate no checksum
is necessary.  For the former case copy-checksum is probably done
anyway, in the latter case the device is likely loopback in which case
the no cache copy is probably not beneficial.

This patch was tested using 200 instances of netperf TCP_RR with
1400 byte request and one byte reply.  Platform is 16 core AMD x86.

No-cache copy disabled:
   672703 tps, 97.13% utilization
   50/90/99% latency:244.31 484.205 1028.41

No-cache copy enabled:
   702113 tps, 96.16% utilization,
   50/90/99% latency 238.56 467.56 956.955

Using 14000 byte request and response sizes demonstrate the
effects more dramatically:

No-cache copy disabled:
   79571 tps, 34.34 %utlization
   50/90/95% latency 1584.46 2319.59 5001.76

No-cache copy enabled:
   83856 tps, 34.81% utilization
   50/90/95% latency 2508.42 2622.62 2735.88

Note especially the effect on latency tail (95th percentile).

This seems to provide a nice performance improvement and is
consistent in the tests I ran.  Presumably, this would provide
the greatest benfits in the presence of an application workload
stressing the cache and a lot of transmit data happening.
Signed-off-by: NTom Herbert <therbert@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In contrast to SIOCOUTQ which returns the amount of data sent
but not yet acknowledged plus data not yet sent this patch only
returns the data not sent.

For various methods of live streaming bitrate control it may
be helpful to know how much data are in the tcp outqueue are
not sent yet.
Signed-off-by: NMario Schuknecht <m.schuknecht@dresearch.de>
Signed-off-by: NSteffen Sledz <sledz@dresearch.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Now, TCP_CHECK_TIMER is not used for debuging, it does nothing.
And, it has been there for several years, maybe 6 years.

Remove it to keep code clearer.
Signed-off-by: NShan Wei <shanwei@cn.fujitsu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Quoting Ben Hutchings: we presumably won't be defining features that
can only be enabled on 64-bit architectures.

Occurences found by `grep -r` on net/, drivers/net, include/

[ Move features and vlan_features next to each other in
  struct netdev, as per Eric Dumazet's suggestion -DaveM ]
Signed-off-by: NMichał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Use TCP_MIN_MSS instead of constant 64.
Reported-by: NMin Zhang <mzhang@mvista.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As noted by Steve Chen, since commit
f5fff5dc ("tcp: advertise MSS
requested by user") we can end up with a situation where
tcp_select_initial_window() does a divide by a zero (or
even negative) mss value.

The problem is that sometimes we effectively subtract
TCPOLEN_TSTAMP_ALIGNED and/or TCPOLEN_MD5SIG_ALIGNED from the mss.

Fix this by increasing the minimum from 8 to 64.
Reported-by: NSteve Chen <schen@mvista.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Robin Holt tried to boot a 16TB machine and found some limits were
reached : sysctl_tcp_mem[2], sysctl_udp_mem[2]

We can switch infrastructure to use long "instead" of "int", now
atomic_long_t primitives are available for free.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Reported-by: NRobin Holt <holt@sgi.com>
Reviewed-by: NRobin Holt <holt@sgi.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Coalesce long formats.
Align arguments.
Remove KERN_<level>.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Fixes kernel bugzilla #16603

tcp_sendmsg() truncates iov_len to an 'int' which a 4GB write to write
zero bytes, for example.

There is also the problem higher up of how verify_iovec() works.  It
wants to prevent the total length from looking like an error return
value.

However it does this using 'int', but syscalls return 'long' (and
thus signed 64-bit on 64-bit machines).  So it could trigger
false-positives on 64-bit as written.  So fix it to use 'long'.
Reported-by: NOlaf Bonorden <bono@onlinehome.de>
Reported-by: NDaniel Büse <dbuese@gmx.de>
Reported-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If a RST comes in immediately after checking sk->sk_err, tcp_poll will
return POLLIN but not POLLOUT.  Fix this by checking sk->sk_err at the end
of tcp_poll.  Additionally, ensure the correct order of operations on SMP
machines with memory barriers.
Signed-off-by: NTom Marshall <tdm.code@gmail.com>
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch provides a "user timeout" support as described in RFC793. The
socket option is also needed for the the local half of RFC5482 "TCP User
Timeout Option".

TCP_USER_TIMEOUT is a TCP level socket option that takes an unsigned int,
when > 0, to specify the maximum amount of time in ms that transmitted
data may remain unacknowledged before TCP will forcefully close the
corresponding connection and return ETIMEDOUT to the application. If
0 is given, TCP will continue to use the system default.

Increasing the user timeouts allows a TCP connection to survive extended
periods without end-to-end connectivity. Decreasing the user timeouts
allows applications to "fail fast" if so desired. Otherwise it may take
upto 20 minutes with the current system defaults in a normal WAN
environment.

The socket option can be made during any state of a TCP connection, but
is only effective during the synchronized states of a connection
(ESTABLISHED, FIN-WAIT-1, FIN-WAIT-2, CLOSE-WAIT, CLOSING, or LAST-ACK).
Moreover, when used with the TCP keepalive (SO_KEEPALIVE) option,
TCP_USER_TIMEOUT will overtake keepalive to determine when to close a
connection due to keepalive failure.

The option does not change in anyway when TCP retransmits a packet, nor
when a keepalive probe will be sent.

This option, like many others, will be inherited by an acceptor from its
listener.
Signed-off-by: NH.K. Jerry Chu <hkchu@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This issue come from ruby language community. Below test program
hang up when only run on Linux.

	% uname -mrsv
	Linux 2.6.26-2-486 #1 Sat Dec 26 08:37:39 UTC 2009 i686
	% ruby -rsocket -ve '
	BasicSocket.do_not_reverse_lookup = true
	serv = TCPServer.open("127.0.0.1", 0)
	s1 = TCPSocket.open("127.0.0.1", serv.addr[1])
	s2 = serv.accept
	s2.close
	s1.write("a") rescue p $!
	s1.write("a") rescue p $!
	Thread.new {
	  s1.write("a")
	}.join'
	ruby 1.9.3dev (2010-07-06 trunk 28554) [i686-linux]
	#<Errno::EPIPE: Broken pipe>
	[Hang Here]

FreeBSD, Solaris, Mac doesn't. because Ruby's write() method call
select() internally. and tcp_poll has a bug.

SUS defined 'ready for writing' of select() as following.

|  A descriptor shall be considered ready for writing when a call to an output
|  function with O_NONBLOCK clear would not block, whether or not the function
|  would transfer data successfully.

That said, EPIPE situation is clearly one of 'ready for writing'.

We don't have read-side issue because tcp_poll() already has read side
shutdown care.

|        if (sk->sk_shutdown & RCV_SHUTDOWN)
|                mask |= POLLIN | POLLRDNORM | POLLRDHUP;

So, Let's insert same logic in write side.

- reference url
  http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/31065
  http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/31068Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As discovered by Anton Blanchard, current code to autotune 
tcp_death_row.sysctl_max_tw_buckets, sysctl_tcp_max_orphans and
sysctl_max_syn_backlog makes little sense.

The bigger a page is, the less tcp_max_orphans is : 4096 on a 512GB
machine in Anton's case.

(tcp_hashinfo.bhash_size * sizeof(struct inet_bind_hashbucket))
is much bigger if spinlock debugging is on. Its wrong to select bigger
limits in this case (where kernel structures are also bigger)

bhash_size max is 65536, and we get this value even for small machines. 

A better ground is to use size of ehash table, this also makes code
shorter and more obvious.

Based on a patch from Anton, and another from David.
Reported-and-tested-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As reported by Anton Blanchard when we use
percpu_counter_read_positive() to make our orphan socket limit checks,
the check can be off by up to num_cpus_online() * batch (which is 32
by default) which on a 128 cpu machine can be as large as the default
orphan limit itself.

Fix this by doing the full expensive sum check if the optimized check
triggers.
Reported-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Acked-by: NEric Dumazet <eric.dumazet@gmail.com>

Initial TCP thin-stream commit did not add getsockopt support for the new
socket options: TCP_THIN_LINEAR_TIMEOUTS and TCP_THIN_DUPACK. This adds support
for them.
Signed-off-by: NJosh Hunt <johunt@akamai.com>
Tested-by: NAndreas Petlund <apetlund@simula.no>
Acked-by: NAndreas Petlund <apetlund@simula.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

There is a bug in do_tcp_setsockopt(net/ipv4/tcp.c),
TCP_COOKIE_TRANSACTIONS case.
In some cases (when tp->cookie_values == NULL) new tcp_cookie_values
structure can be allocated (at cvp), but not bound to
tp->cookie_values. So a memory leak occurs.
Signed-off-by: NDmitry Popov <dp@highloadlab.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

rfs: call sock_rps_record_flow() in tcp_splice_read()

call sock_rps_record_flow() in tcp_splice_read(), so the applications using
splice(2) or sendfile(2) can utilize RFS.
Signed-off-by: NChangli Gao <xiaosuo@gmail.com>
----
 net/ipv4/tcp.c |    1 +
 1 file changed, 1 insertion(+)
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

a new boolean flag no_autobind is added to structure proto to avoid the autobind
calls when the protocol is TCP. Then sock_rps_record_flow() is called int the
TCP's sendmsg() and sendpage() pathes.
Signed-off-by: NChangli Gao <xiaosuo@gmail.com>
----
 include/net/inet_common.h |    4 ++++
 include/net/sock.h        |    1 +
 include/net/tcp.h         |    8 ++++----
 net/ipv4/af_inet.c        |   15 +++++++++------
 net/ipv4/tcp.c            |   11 +++++------
 net/ipv4/tcp_ipv4.c       |    3 +++
 net/ipv6/af_inet6.c       |    8 ++++----
 net/ipv6/tcp_ipv6.c       |    3 +++
 8 files changed, 33 insertions(+), 20 deletions(-)
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

CodingStyle cleanups

EXPORT_SYMBOL should immediately follow the symbol declaration.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

use this_cpu_ptr(p) instead of per_cpu_ptr(p, smp_processor_id())
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

i've found that tcp_close() can be called for an already closed
socket, but still sends reset in this case (tcp_send_active_reset())
which seems to be incorrect.  Moreover, a packet with reset is sent
with different source port as original port number has been already
cleared on socket.  Besides that incrementing stat counter for
LINUX_MIB_TCPABORTONCLOSE also does not look correct in this case.

Initially this issue was found on 2.6.18-x RHEL5 kernel, but the same
seems to be true for the current mainstream kernel (checked on
2.6.35-rc3).  Please, correct me if i missed something.

How that happens:

1) the server receives a packet for socket in TCP_CLOSE_WAIT state
   that triggers a tcp_reset():

Call Trace:
 <IRQ>  [<ffffffff8025b9b9>] tcp_reset+0x12f/0x1e8
 [<ffffffff80046125>] tcp_rcv_state_process+0x1c0/0xa08
 [<ffffffff8003eb22>] tcp_v4_do_rcv+0x310/0x37a
 [<ffffffff80028bea>] tcp_v4_rcv+0x74d/0xb43
 [<ffffffff8024ef4c>] ip_local_deliver_finish+0x0/0x259
 [<ffffffff80037131>] ip_local_deliver+0x200/0x2f4
 [<ffffffff8003843c>] ip_rcv+0x64c/0x69f
 [<ffffffff80021d89>] netif_receive_skb+0x4c4/0x4fa
 [<ffffffff80032eca>] process_backlog+0x90/0xec
 [<ffffffff8000cc50>] net_rx_action+0xbb/0x1f1
 [<ffffffff80012d3a>] __do_softirq+0xf5/0x1ce
 [<ffffffff8001147a>] handle_IRQ_event+0x56/0xb0
 [<ffffffff8006334c>] call_softirq+0x1c/0x28
 [<ffffffff80070476>] do_softirq+0x2c/0x85
 [<ffffffff80070441>] do_IRQ+0x149/0x152
 [<ffffffff80062665>] ret_from_intr+0x0/0xa
 <EOI>  [<ffffffff80008a2e>] __handle_mm_fault+0x6cd/0x1303
 [<ffffffff80008903>] __handle_mm_fault+0x5a2/0x1303
 [<ffffffff80033a9d>] cache_free_debugcheck+0x21f/0x22e
 [<ffffffff8006a263>] do_page_fault+0x49a/0x7dc
 [<ffffffff80066487>] thread_return+0x89/0x174
 [<ffffffff800c5aee>] audit_syscall_exit+0x341/0x35c
 [<ffffffff80062e39>] error_exit+0x0/0x84

tcp_rcv_state_process()
...  // (sk_state == TCP_CLOSE_WAIT here)
...
        /* step 2: check RST bit */
        if(th->rst) {
                tcp_reset(sk);
                goto discard;
        }
...
---------------------------------
tcp_rcv_state_process
 tcp_reset
  tcp_done
   tcp_set_state(sk, TCP_CLOSE);
     inet_put_port
      __inet_put_port
       inet_sk(sk)->num = 0;

   sk->sk_shutdown = SHUTDOWN_MASK;

2) After that the process (socket owner) tries to write something to
   that socket and "inet_autobind" sets a _new_ (which differs from
   the original!) port number for the socket:

 Call Trace:
  [<ffffffff80255a12>] inet_bind_hash+0x33/0x5f
  [<ffffffff80257180>] inet_csk_get_port+0x216/0x268
  [<ffffffff8026bcc9>] inet_autobind+0x22/0x8f
  [<ffffffff80049140>] inet_sendmsg+0x27/0x57
  [<ffffffff8003a9d9>] do_sock_write+0xae/0xea
  [<ffffffff80226ac7>] sock_writev+0xdc/0xf6
  [<ffffffff800680c7>] _spin_lock_irqsave+0x9/0xe
  [<ffffffff8001fb49>] __pollwait+0x0/0xdd
  [<ffffffff8008d533>] default_wake_function+0x0/0xe
  [<ffffffff800a4f10>] autoremove_wake_function+0x0/0x2e
  [<ffffffff800f0b49>] do_readv_writev+0x163/0x274
  [<ffffffff80066538>] thread_return+0x13a/0x174
  [<ffffffff800145d8>] tcp_poll+0x0/0x1c9
  [<ffffffff800c56d3>] audit_syscall_entry+0x180/0x1b3
  [<ffffffff800f0dd0>] sys_writev+0x49/0xe4
  [<ffffffff800622dd>] tracesys+0xd5/0xe0

3) sendmsg fails at last with -EPIPE (=> 'write' returns -EPIPE in userspace):

F: tcp_sendmsg1 -EPIPE: sk=ffff81000bda00d0, sport=49847, old_state=7, new_state=7, sk_err=0, sk_shutdown=3

Call Trace:
 [<ffffffff80027557>] tcp_sendmsg+0xcb/0xe87
 [<ffffffff80033300>] release_sock+0x10/0xae
 [<ffffffff8016f20f>] vgacon_cursor+0x0/0x1a7
 [<ffffffff8026bd32>] inet_autobind+0x8b/0x8f
 [<ffffffff8003a9d9>] do_sock_write+0xae/0xea
 [<ffffffff80226ac7>] sock_writev+0xdc/0xf6
 [<ffffffff800680c7>] _spin_lock_irqsave+0x9/0xe
 [<ffffffff8001fb49>] __pollwait+0x0/0xdd
 [<ffffffff8008d533>] default_wake_function+0x0/0xe
 [<ffffffff800a4f10>] autoremove_wake_function+0x0/0x2e
 [<ffffffff800f0b49>] do_readv_writev+0x163/0x274
 [<ffffffff80066538>] thread_return+0x13a/0x174
 [<ffffffff800145d8>] tcp_poll+0x0/0x1c9
 [<ffffffff800c56d3>] audit_syscall_entry+0x180/0x1b3
 [<ffffffff800f0dd0>] sys_writev+0x49/0xe4
 [<ffffffff800622dd>] tracesys+0xd5/0xe0

tcp_sendmsg()
...
        /* Wait for a connection to finish. */
        if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) {
                int old_state = sk->sk_state;
                if ((err = sk_stream_wait_connect(sk, &timeo)) != 0) {
if (f_d && (err == -EPIPE)) {
        printk("F: tcp_sendmsg1 -EPIPE: sk=%p, sport=%u, old_state=%d, new_state=%d, "
                "sk_err=%d, sk_shutdown=%d\n",
                sk, ntohs(inet_sk(sk)->sport), old_state, sk->sk_state,
                sk->sk_err, sk->sk_shutdown);
        dump_stack();
}
                        goto out_err;
                }
        }
...

4) Then the process (socket owner) understands that it's time to close
   that socket and does that (and thus triggers sending reset packet):

Call Trace:
...
 [<ffffffff80032077>] dev_queue_xmit+0x343/0x3d6
 [<ffffffff80034698>] ip_output+0x351/0x384
 [<ffffffff80251ae9>] dst_output+0x0/0xe
 [<ffffffff80036ec6>] ip_queue_xmit+0x567/0x5d2
 [<ffffffff80095700>] vprintk+0x21/0x33
 [<ffffffff800070f0>] check_poison_obj+0x2e/0x206
 [<ffffffff80013587>] poison_obj+0x36/0x45
 [<ffffffff8025dea6>] tcp_send_active_reset+0x15/0x14d
 [<ffffffff80023481>] dbg_redzone1+0x1c/0x25
 [<ffffffff8025dea6>] tcp_send_active_reset+0x15/0x14d
 [<ffffffff8000ca94>] cache_alloc_debugcheck_after+0x189/0x1c8
 [<ffffffff80023405>] tcp_transmit_skb+0x764/0x786
 [<ffffffff8025df8a>] tcp_send_active_reset+0xf9/0x14d
 [<ffffffff80258ff1>] tcp_close+0x39a/0x960
 [<ffffffff8026be12>] inet_release+0x69/0x80
 [<ffffffff80059b31>] sock_release+0x4f/0xcf
 [<ffffffff80059d4c>] sock_close+0x2c/0x30
 [<ffffffff800133c9>] __fput+0xac/0x197
 [<ffffffff800252bc>] filp_close+0x59/0x61
 [<ffffffff8001eff6>] sys_close+0x85/0xc7
 [<ffffffff800622dd>] tracesys+0xd5/0xe0

So, in brief:

* a received packet for socket in TCP_CLOSE_WAIT state triggers
  tcp_reset() which clears inet_sk(sk)->num and put socket into
  TCP_CLOSE state

* an attempt to write to that socket forces inet_autobind() to get a
  new port (but the write itself fails with -EPIPE)

* tcp_close() called for socket in TCP_CLOSE state sends an active
  reset via socket with newly allocated port

This adds an additional check in tcp_close() for already closed
sockets. We do not want to send anything to closed sockets.
Signed-off-by: NKonstantin Khorenko <khorenko@openvz.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

unify tcp flag macros: TCPHDR_FIN, TCPHDR_SYN, TCPHDR_RST, TCPHDR_PSH,
TCPHDR_ACK, TCPHDR_URG, TCPHDR_ECE and TCPHDR_CWR. TCBCB_FLAG_* are replaced
with the corresponding TCPHDR_*.
Signed-off-by: NChangli Gao <xiaosuo@gmail.com>
----
 include/net/tcp.h                      |   24 ++++++-------
 net/ipv4/tcp.c                         |    8 ++--
 net/ipv4/tcp_input.c                   |    2 -
 net/ipv4/tcp_output.c                  |   59 ++++++++++++++++-----------------
 net/netfilter/nf_conntrack_proto_tcp.c |   32 ++++++-----------
 net/netfilter/xt_TCPMSS.c              |    4 --
 6 files changed, 58 insertions(+), 71 deletions(-)
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

tcp_md5_hash_skb_data() should handle skb->frag_list, and eventually
recurse.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Also added an explicit break; to avoid
a fallthrough in net/ipv4/tcp_input.c
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

TCP MD5 support uses percpu data for temporary storage. It currently
disables preemption so that same storage cannot be reclaimed by another
thread on same cpu.

We also have to make sure a softirq handler wont try to use also same
context. Various bug reports demonstrated corruptions.

Fix is to disable preemption and BH.
Reported-by: NBhaskar Dutta <bhaskie@gmail.com>
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

RFC 1122 says the following:
...
  Keep-alive packets MUST only be sent when no data or
  acknowledgement packets have been received for the
  connection within an interval.
...

The acknowledgement packet is reseting the keepalive
timer but the data packet isn't. This patch fixes it by
checking the timestamp of the last received data packet
too when the keepalive timer expires.
Signed-off-by: NFlavio Leitner <fleitner@redhat.com>
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Acked-by: NIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Sparse can help us find endianness bugs, but we need to make some
cleanups to be able to more easily spot real bugs.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Define a new function to return the waitqueue of a "struct sock".

static inline wait_queue_head_t *sk_sleep(struct sock *sk)
{
	return sk->sk_sleep;
}

Change all read occurrences of sk_sleep by a call to this function.

Needed for a future RCU conversion. sk_sleep wont be a field directly
available.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

tcp_read_sock() can have a eat skbs without immediately advancing copied_seq.
This can cause a panic in tcp_collapse() if it is called as a result
of the recv_actor dropping the socket lock.

A userspace program that splices data from a socket to either another
socket or to a file can trigger this bug.
Signed-off-by: NSteven J. Magnani <steve@digidescorp.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: NTejun Heo <tj@kernel.org>
Guess-its-ok-by: NChristoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>

Under NET_DMA, data transfer can grind to a halt when userland issues a
large read on a socket with a high RCVLOWAT (i.e., 512 KB for both).
This appears to be because the NET_DMA design queues up lots of memcpy
operations, but doesn't issue or wait for them (and thus free the
associated skbs) until it is time for tcp_recvmesg() to return.
The socket hangs when its TCP window goes to zero before enough data is
available to satisfy the read.

Periodically issue asynchronous memcpy operations, and free skbs for ones
that have completed, to prevent sockets from going into zero-window mode.
Signed-off-by: NSteven J. Magnani <steve@digidescorp.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

From: Alexandra.Kossovsky@oktetlabs.ru

Fixes kernel bugzilla #15541
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch enables fast retransmissions after one dupACK for
TCP if the stream is identified as thin. This will reduce
latencies for thin streams that are not able to trigger fast
retransmissions due to high packet interarrival time. This
mechanism is only active if enabled by iocontrol or syscontrol
and the stream is identified as thin.
Signed-off-by: NAndreas Petlund <apetlund@simula.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch will make TCP use only linear timeouts if the
stream is thin. This will help to avoid the very high latencies
that thin stream suffer because of exponential backoff. This
mechanism is only active if enabled by iocontrol or syscontrol
and the stream is identified as thin. A maximum of 6 linear
timeouts is tried before exponential backoff is resumed.
Signed-off-by: NAndreas Petlund <apetlund@simula.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add __percpu sparse annotations to net.

These annotations are to make sparse consider percpu variables to be
in a different address space and warn if accessed without going
through percpu accessors.  This patch doesn't affect normal builds.

The macro and type tricks around snmp stats make things a bit
interesting.  DEFINE/DECLARE_SNMP_STAT() macros mark the target field
as __percpu and SNMP_UPD_PO_STATS() macro is updated accordingly.  All
snmp_mib_*() users which used to cast the argument to (void **) are
updated to cast it to (void __percpu **).
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NDavid S. Miller <davem@davemloft.net>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Vlad Yasevich <vladislav.yasevich@hp.com>
Cc: netdev@vger.kernel.org
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Slightly optimize tcp_sendmsg since NETIF_F_SG is used many
times iteratively in the loop. The only other modification is
to change:
			} else if (i == MAX_SKB_FRAGS ||
				   (!i &&
				   !(sk->sk_route_caps & NETIF_F_SG))) {
	to:
			} else if (i == MAX_SKB_FRAGS || !sg) {

The reason why this change is correct: this code (other than
the MAX_SKB_FRAGS case) executes only due to the else part
of: "if (skb_tailroom(skb) > 0) {" - i.e. there was no space
in the skb to put the data inline. Hence SG is false is a
sufficient condition, and there is no way a fragment can be
added to the skb.

Changelog:
	- Added the above explanation for the change
Signed-off-by: NKrishna Kumar <krkumar2@in.ibm.com>
Acked-by: NIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Remove unrequired operations in tcp_push()

Changelog:
	Removed a temporary skb variable from tcp_push()
Signed-off-by: NKrishna Kumar <krkumar2@in.ibm.com>
Acked-by: NIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

GCC even warns about it, as reported by Andrew Morton:

net/ipv4/tcp.c: In function 'do_tcp_getsockopt':
net/ipv4/tcp.c:2544: warning: comparison is always false due to limited range of data type
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Provide per socket control of the TCP cookie option and SYN/SYNACK data.

This is a straightforward re-implementation of an earlier (year-old)
patch that no longer applies cleanly, with permission of the original
author (Adam Langley):

    http://thread.gmane.org/gmane.linux.network/102586

The principle difference is using a TCP option to carry the cookie nonce,
instead of a user configured offset in the data.

Allocations have been rearranged to avoid requiring GFP_ATOMIC.

Requires:
   net: TCP_MSS_DEFAULT, TCP_MSS_DESIRED
   TCPCT part 1c: sysctl_tcp_cookie_size, socket option TCP_COOKIE_TRANSACTIONS
   TCPCT part 1d: define TCP cookie option, extend existing struct's

Signed-off-by: William.Allen.Simpson@gmail.com
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Define (missing) hash message size for SHA1.

Define hashing size constants specific to TCP cookies.

Add new function: tcp_cookie_generator().

Maintain global secret values for tcp_cookie_generator().

This is a significantly revised implementation of earlier (15-year-old)
Photuris [RFC-2522] code for the KA9Q cooperative multitasking platform.

Linux RCU technique appears to be well-suited to this application, though
neither of the circular queue items are freed.

These functions will also be used in subsequent patches that implement
additional features.

Signed-off-by: William.Allen.Simpson@gmail.com
Acked-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>