Commit Graph

324 Commits

Author SHA1 Message Date
Ilpo Järvinen 0e3a4803aa [TCP]: Force TSO splits to MSS boundaries
If snd_wnd - snd_nxt wasn't multiple of MSS, skb was split on
odd boundary by the callers of tcp_window_allows.

We try really hard to avoid unnecessary modulos. Therefore the
old caller side check "if (skb->len < limit)" was too wide as
well because limit is not bound in any way to skb->len and can
cause spurious testing for trimming in the middle of the queue
while we only wanted that to happen at the tail of the queue.
A simple additional caller side check for tcp_write_queue_tail
would likely have resulted 2 x modulos because the limit would
have to be first calculated from window, however, doing that
unnecessary modulo is not mandatory. After a minor change to
the algorithm, simply determine first if the modulo is needed
at all and at that point immediately decide also from which
value it should be calculated from.

This approach also kills some duplicated code.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28 15:00:06 -08:00
Eric Dumazet b92edbe0b8 [TCP] Avoid two divides in tcp_output.c
Because 'free_space' variable in __tcp_select_window() is signed,
expression (free_space / 2) forces compiler to emit an integer divide.

This can be changed to a plain right shift, less expensive.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28 14:59:41 -08:00
Ilpo Järvinen bd515c3e48 [TCP]: Fix TSO deferring
I'd say that most of what tcp_tso_should_defer had in between
there was dead code because of this.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28 14:59:36 -08:00
Ilpo Järvinen 6859d49475 [TCP]: Abstract tp->highest_sack accessing & point to next skb
Pointing to the next skb is necessary to avoid referencing
already SACKed skbs which will soon be on a separate list.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28 14:55:46 -08:00
Ilpo Järvinen 234b686070 [TCP]: Add tcp_for_write_queue_from_safe and use it in mtu_probe
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28 14:55:43 -08:00
Ilpo Järvinen d67c58e9ae [TCP]: Remove local variable and use packets_in_flight directly
Lines won't be that long and it's compiler's job to optimize
them.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28 14:55:43 -08:00
Ilpo Järvinen 50c4817e99 [TCP]: MTUprobe: prepare skb fields earlier
They better be valid when call to write_queue functions is made
once things that follow are going in.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28 14:55:42 -08:00
Pavel Emelyanov df97c708d5 [NET]: Eliminate unused argument from sk_stream_alloc_pskb
The 3rd argument is always zero (according to grep :) Eliminate
it and merge the function with sk_stream_alloc_skb.

This saves 44 more bytes, and together with the previous patch
we have:

add/remove: 1/0 grow/shrink: 0/8 up/down: 183/-751 (-568)
function                                     old     new   delta
sk_stream_alloc_skb                            -     183    +183
ip_rt_init                                   529     525      -4
arp_ignore                                   112     107      -5
__inet_lookup_listener                       284     274     -10
tcp_sendmsg                                 2583    2481    -102
tcp_sendpage                                1449    1300    -149
tso_fragment                                 417     258    -159
tcp_fragment                                1149     988    -161
__tcp_push_pending_frames                   1998    1837    -161

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28 14:55:08 -08:00
Ilpo Järvinen 8512430e55 [TCP]: Move FRTO checks out from write queue abstraction funcs
Better place exists in update_send_head (other non-queue related
adjustments are done there as well) which is the only caller of
tcp_advance_send_head (now that the bogus call from mtu_probe is
gone).

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28 14:55:05 -08:00
Ilpo Järvinen 68f8353b48 [TCP]: Rewrite SACK block processing & sack_recv_cache use
Key points of this patch are:

  - In case new SACK information is advance only type, no skb
    processing below previously discovered highest point is done
  - Optimize cases below highest point too since there's no need
    to always go up to highest point (which is very likely still
    present in that SACK), this is not entirely true though
    because I'm dropping the fastpath_skb_hint which could
    previously optimize those cases even better. Whether that's
    significant, I'm not too sure.

Currently it will provide skipping by walking. Combined with
RB-tree, all skipping would become fast too regardless of window
size (can be done incrementally later).

Previously a number of cases in TCP SACK processing fails to
take advantage of costly stored information in sack_recv_cache,
most importantly, expected events such as cumulative ACK and new
hole ACKs. Processing on such ACKs result in rather long walks
building up latencies (which easily gets nasty when window is
huge). Those latencies are often completely unnecessary
compared with the amount of _new_ information received, usually
for cumulative ACK there's no new information at all, yet TCP
walks whole queue unnecessary potentially taking a number of
costly cache misses on the way, etc.!

Since the inclusion of highest_sack, there's a lot information
that is very likely redundant (SACK fastpath hint stuff,
fackets_out, highest_sack), though there's no ultimate guarantee
that they'll remain the same whole the time (in all unearthly
scenarios). Take advantage of this knowledge here and drop
fastpath hint and use direct access to highest SACKed skb as
a replacement.

Effectively "special cased" fastpath is dropped. This change
adds some complexity to introduce better coveraged "fastpath",
though the added complexity should make TCP behave more cache
friendly.

The current ACK's SACK blocks are compared against each cached
block individially and only ranges that are new are then scanned
by the high constant walk. For other parts of write queue, even
when in previously known part of the SACK blocks, a faster skip
function is used (if necessary at all). In addition, whenever
possible, TCP fast-forwards to highest_sack skb that was made
available by an earlier patch. In typical case, no other things
but this fast-forward and mandatory markings after that occur
making the access pattern quite similar to the former fastpath
"special case".

DSACKs are special case that must always be walked.

The local to recv_sack_cache copying could be more intelligent
w.r.t DSACKs which are likely to be there only once but that
is left to a separate patch.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28 14:54:07 -08:00
Ilpo Järvinen a47e5a988a [TCP]: Convert highest_sack to sk_buff to allow direct access
It is going to replace the sack fastpath hint quite soon... :-)

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28 14:54:03 -08:00
Ilpo Jrvinen 4e67d876ce [TCP]: NAGLE_PUSH seems to be a wrong way around
The comment in tcp_nagle_test suggests that. This bug is very
very old, even 2.4.0 seems to have it.

Signed-off-by: Ilpo Jrvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-12-05 05:37:31 -08:00
Ilpo Järvinen 7f9c33e515 [TCP] MTUprobe: Cleanup send queue check (no need to loop)
The original code has striking complexity to perform a query
which can be reduced to a very simple compare.

FIN seqno may be included to write_seq but it should not make
any significant difference here compared to skb->len which was
used previously. One won't end up there with SYN still queued.

Use of write_seq check guarantees that there's a valid skb in
send_head so I removed the extra check.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Acked-by: John Heffner <jheffner@psc.edu>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2007-11-23 19:10:56 +08:00
Ilpo Järvinen 91cc17c0e5 [TCP]: MTUprobe: receiver window & data available checks fixed
It seems that the checked range for receiver window check should
begin from the first rather than from the last skb that is going
to be included to the probe. And that can be achieved without
reference to skbs at all, snd_nxt and write_seq provides the
correct seqno already. Plus, it SHOULD account packets that are
necessary to trigger fast retransmit [RFC4821].

Location of snd_wnd < probe_size/size_needed check is bogus
because it will cause the other if() match as well (due to
snd_nxt >= snd_una invariant).

Removed dead obvious comment.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2007-11-23 19:08:16 +08:00
Ilpo Jrvinen 6e42141009 [TCP] MTUprobe: fix potential sk_send_head corruption
When the abstraction functions got added, conversion here was
made incorrectly. As a result, the skb may end up pointing
to skb which got included to the probe skb and then was freed.
For it to trigger, however, skb_transmit must fail sending as
well.

Signed-off-by: Ilpo Jrvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-11-19 23:24:09 -08:00
Ilpo Järvinen b08d6cb22c [TCP]: Limit processing lost_retrans loop to work-to-do cases
This addition of lost_retrans_low to tcp_sock might be
unnecessary, it's not clear how often lost_retrans worker is
executed when there wasn't work to do.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-11 17:36:13 -07:00
Ilpo Järvinen 29d0a309d1 [TCP]: Fix two off-by-one errors in fackets_out adjusting logic
1) Passing wrong skb to tcp_adjust_fackets_out could corrupt
fastpath_cnt_hint as tcp_skb_pcount(next_skb) is not included
to it if hint points exactly to the next_skb (it's lagging
behind, see sacktag).

2) When fastpath_skb_hint is put backwards to avoid dangling
skb reference, the skb's pcount must also be removed from count
(not included like above).

Reported by Cedric Le Goater <legoater@free.fr>

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10 16:54:47 -07:00
Ilpo Järvinen dc86967b54 [TCP]: No fackets_out/highest_sack tuning when SACK isn't enabled
This was found due to bug report from Cedric Le Goater though
it turned this turned out to be unrelated bug.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10 16:53:58 -07:00
Ilpo Järvinen a6963a6b3d [TCP]: Re-place highest_sack check to a more robust position
I previously added checking to position that is rather poor as
state has already been adjusted quite a bit. Re-placing it above
all state changes should be more robust though the return should
never ever get executed regardless of its place :-).

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10 16:52:38 -07:00
Ilpo Järvinen b76892051c [TCP]: Avoid clearing sacktag hint in trivial situations
There's no reason to clear the sacktag skb hint when small part
of the rexmit queue changes. Account changes (if any) instead when
fragmenting/collapsing. RTO/FRTO do not touch SACKED_ACKED bits so
no need to discard SACK tag hint at all.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10 16:52:12 -07:00
Ilpo Järvinen 5af4ec236f [TCP]: clear_all_retrans_hints prefixed by tcp_
In addition, fix its function comment spacing.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
2007-10-10 16:52:09 -07:00
Ilpo Järvinen 91fed7a15c [TCP]: Make fackets_out accurate
Substraction for fackets_out is unconditional when snd_una
advances, thus there's no need to do it inside the loop. Just
make sure correct bounds are honored.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10 16:52:08 -07:00
Ilpo Järvinen 0dde7b5404 [TCP]: Maintain highest_sack accurately to the highest skb
In general, it should not be necessary to call tcp_fragment for
already SACKed skbs, but it's better to be safe than sorry. And
indeed, it can be called from sacktag when a DSACK arrives or
some ACK (with SACK) reordering occurs (sacktag could be made
to avoid the call in the latter case though I'm not sure if it's
worth of the trouble and added complexity to cover such marginal
case).

The collapse case has return for SACKED_ACKED case earlier, so
just WARN_ON if internal inconsistency is detected for some
reason.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10 16:52:08 -07:00
Ilpo Järvinen 356f89e12e [NET] Cleanup: DIV_ROUND_UP
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10 16:48:30 -07:00
Ilpo Järvinen 6ff03ac355 [TCP]: tcp_packets_out_inc to tcp_output.c (no callers elsewhere)
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10 16:48:28 -07:00
Ilpo Järvinen e9144bd8da [TCP]: Remove unnecessary wrapper tcp_packets_out_dec
Makes caller side more obvious, there's no need to have
a wrapper for this oneliner!

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10 16:48:27 -07:00
Ilpo Järvinen e60402d0a9 [TCP]: Move sack_ok access to obviously named funcs & cleanup
Previously code had IsReno/IsFack defined as macros that were
local to tcp_input.c though sack_ok field has user elsewhere too
for the same purpose. This changes them to static inlines as
preferred according the current coding style and unifies the
access to sack_ok across multiple files. Magic bitops of sack_ok
for FACK and DSACK are also abstracted to functions with
appropriate names.

Note:
- One sack_ok = 1 remains but that's self explanary, i.e., it
  enables sack
- Couple of !IsReno cases are changed to tcp_is_sack
- There were no users for IsDSack => I dropped it

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10 16:48:00 -07:00
Ilpo Järvinen 005903bc3a [TCP]: Left out sync->verify (the new meaning of it) & definify
Left_out was dropped a while ago, thus leaving verifying
consistency of the "left out" as only task for the function in
question. Thus make it's name more appropriate.

In addition, it is intentionally converted to #define instead
of static inline because the location of the invariant failure
is the most important thing to have if this ever triggers. I
think it would have been helpful e.g. in this case where the
location of the failure point had to be based on some quesswork:
    http://lkml.org/lkml/2007/5/2/464
...Luckily the guesswork seems to have proved to be correct.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10 16:47:57 -07:00
Ilpo Järvinen b5860bbac7 [TCP]: Tighten tcp_sock's belt, drop left_out
It is easily calculable when needed and user are not that many
after all.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10 16:47:55 -07:00
Ilpo Järvinen af610b4ca1 [TCP]: Add tcp_dec_pcount_approx int variant
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10 16:47:54 -07:00
Ilpo Järvinen bdf1ee5d3b [TCP]: Move code from tcp_ecn.h to tcp*.c and tcp.h & remove it
No other users exist for tcp_ecn.h. Very few things remain in
tcp.h, for most TCP ECN functions callers reside within a
single .c file and can be placed there.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10 16:47:54 -07:00
Ilpo Järvinen 539d243fdd [TCP]: Access to highest_sack obsoletes forward_cnt_hint
In addition, added a reference about the purpose of the loop.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10 16:47:53 -07:00
YOSHIFUJI Hideaki 9c681b43fa [NET] IPV4: Fix whitespace errors.
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
2007-07-19 10:43:47 +09:00
Ilpo Järvinen d041005116 [TCP]: SACK fastpath did override adjusted fackets_out
Do same adjustment to SACK fastpath counters provided that
they're valid.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10 22:16:24 -07:00
Randy Dunlap e63340ae6b header cleaning: don't include smp_lock.h when not used
Remove includes of <linux/smp_lock.h> where it is not used/needed.
Suggested by Al Viro.

Builds cleanly on x86_64, i386, alpha, ia64, powerpc, sparc,
sparc64, and arm (all 59 defconfigs).

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 11:15:07 -07:00
Ilpo Järvinen d551e4541d [TCP] FRTO: RFC4138 allows Nagle override when new data must be sent
This is a corner case where less than MSS sized new data thingie
is awaiting in the send queue. For F-RTO to work correctly, a
new data segment must be sent at certain point or F-RTO cannot
be used at all. RFC4138 allows overriding of Nagle at that
point.

Implementation uses frto_counter states 2 and 3 to distinguish
when Nagle override is needed.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-04-30 00:58:16 -07:00
Gerrit Renker 65bb723c95 [TCP]: Update references in two old comments
This updates references to drafts in comments which must be about 10
years old.  Internet draft draft-ietf-tcpimpl-prob-03.txt expired in 1998
and was replaced by RFC 2525 in March 1999.

Section 3.10 of the draft maps almost identically into section 2.17 of RFC
2525: both are entitled "Failure to RST on close with data pending", the
differences in text body amount to a typo and minor sentence change.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-04-28 21:21:46 -07:00
Stephen Hemminger 164891aadf [TCP]: Congestion control API update.
Do some simple changes to make congestion control API faster/cleaner.
* use ktime_t rather than timeval
* merge rtt sampling into existing ack callback
  this means one indirect call versus two per ack.
* use flags bits to store options/settings

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-04-25 22:29:45 -07:00
Ilpo Järvinen 9e412ba763 [TCP]: Sed magic converts func(sk, tp, ...) -> func(sk, ...)
This is (mostly) automated change using magic:

sed -e '/struct sock \*sk/ N' -e '/struct sock \*sk/ N'
    -e '/struct sock \*sk/ N' -e '/struct sock \*sk/ N'
    -e 's|struct sock \*sk,[\n\t ]*struct tcp_sock \*tp\([^{]*\n{\n\)|
	  struct sock \*sk\1\tstruct tcp_sock *tp = tcp_sk(sk);\n|g'
    -e 's|struct sock \*sk, struct tcp_sock \*tp|
	  struct sock \*sk|g' -e 's|sk, tp\([^-]\)|sk\1|g'

Fixed four unused variable (tp) warnings that were introduced.

In addition, manually added newlines after local variables and
tweaked function arguments positioning.

$ gcc --version
gcc (GCC) 4.1.1 20060525 (Red Hat 4.1.1-1)
...
$ codiff -fV built-in.o.old built-in.o.new
net/ipv4/route.c:
  rt_cache_flush |  +14
 1 function changed, 14 bytes added

net/ipv4/tcp.c:
  tcp_setsockopt |   -5
  tcp_sendpage   |  -25
  tcp_sendmsg    |  -16
 3 functions changed, 46 bytes removed

net/ipv4/tcp_input.c:
  tcp_try_undo_recovery |   +3
  tcp_try_undo_dsack    |   +2
  tcp_mark_head_lost    |  -12
  tcp_ack               |  -15
  tcp_event_data_recv   |  -32
  tcp_rcv_state_process |  -10
  tcp_rcv_established   |   +1
 7 functions changed, 6 bytes added, 69 bytes removed, diff: -63

net/ipv4/tcp_output.c:
  update_send_head          |   -9
  tcp_transmit_skb          |  +19
  tcp_cwnd_validate         |   +1
  tcp_write_wakeup          |  -17
  __tcp_push_pending_frames |  -25
  tcp_push_one              |   -8
  tcp_send_fin              |   -4
 7 functions changed, 20 bytes added, 63 bytes removed, diff: -43

built-in.o.new:
 18 functions changed, 40 bytes added, 178 bytes removed, diff: -138

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-04-25 22:29:34 -07:00
Arnaldo Carvalho de Melo 1a4e2d093f [SK_BUFF]: Some more conversions to skb_copy_from_linear_data
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
2007-04-25 22:28:30 -07:00
Arnaldo Carvalho de Melo 27a884dc3c [SK_BUFF]: Convert skb->tail to sk_buff_data_t
So that it is also an offset from skb->head, reduces its size from 8 to 4 bytes
on 64bit architectures, allowing us to combine the 4 bytes hole left by the
layer headers conversion, reducing struct sk_buff size to 256 bytes, i.e. 4
64byte cachelines, and since the sk_buff slab cache is SLAB_HWCACHE_ALIGN...
:-)

Many calculations that previously required that skb->{transport,network,
mac}_header be first converted to a pointer now can be done directly, being
meaningful as offsets or pointers.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-04-25 22:26:28 -07:00
Arnaldo Carvalho de Melo aa8223c7bb [SK_BUFF]: Introduce tcp_hdr(), remove skb->h.th
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-04-25 22:25:26 -07:00
Stephen Hemminger 2de979bd7d [TCP]: whitespace cleanup
Add whitespace around keywords.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-04-25 22:24:13 -07:00
David S. Miller fe067e8ab5 [TCP]: Abstract out all write queue operations.
This allows the write queue implementation to be changed,
for example, to one which allows fast interval searching.

Signed-off-by: David S. Miller <davem@davemloft.net>
2007-04-25 22:24:02 -07:00
Ilpo Järvinen 3cfe3baaf0 [TCP]: Add two new spurious RTO responses to FRTO
New sysctl tcp_frto_response is added to select amongst these
responses:
	- Rate halving based; reuses CA_CWR state (default)
	- Very conservative; used to be the only one available (=1)
	- Undo cwr; undoes ssthresh and cwnd reductions (=2)

The response with rate halving requires a new parameter to
tcp_enter_cwr because FRTO has already reduced ssthresh and
doing a second reduction there has to be prevented. In addition,
to keep things nice on 80 cols screen, a local variable was
added.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-04-25 22:23:23 -07:00
David S. Miller 15d33c070d [TCP]: slow_start_after_idle should influence cwnd validation too
For the cases that slow_start_after_idle are meant to deal
with, it is almost a certainty that the congestion window
tests will think the connection is application limited and
we'll thus decrease the cwnd there too.  This defeats the
whole point of setting slow_start_after_idle to zero.

So test it there too.

We do not cancel out the entire tcp_cwnd_validate() function
so that if the sysctl is changed we still have the validation
state maintained.

Signed-off-by: David S. Miller <davem@davemloft.net>
2007-04-09 13:31:15 -07:00
John Heffner 84565070e4 [TCP]: Do receiver-side SWS avoidance for rcvbuf < MSS.
Signed-off-by: John Heffner <jheffner@psc.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-04-02 13:56:32 -07:00
Ilpo Järvinen 600ff0c24b [TCP]: Prevent pseudo garbage in SYN's advertized window
TCP may advertize up to 16-bits window in SYN packets (no window
scaling allowed). At the same time, TCP may have rcv_wnd
(32-bits) that does not fit to 16-bits without window scaling
resulting in pseudo garbage into advertized window from the
low-order bits of rcv_wnd. This can happen at least when
mss <= (1<<wscale) (see tcp_select_initial_window). This patch
fixes the handling of SYN advertized windows (compile tested
only).

In worst case (which is unlikely to occur though), the receiver
advertized window could be just couple of bytes. I'm not sure
that such situation would be handled very well at all by the
receiver!? Fortunately, the situation normalizes after the
first non-SYN ACK is received because it has the correct,
scaled window.

Alternatively, tcp_select_initial_window could be changed to
prevent too large rcv_wnd in the first place.

[ tcp_make_synack() has the same bug, and I've added a fix for
  that to this patch -DaveM ]

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-02-13 12:42:11 -08:00
YOSHIFUJI Hideaki e905a9edab [NET] IPV4: Fix whitespace errors.
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-02-10 23:19:39 -08:00
John Heffner 104439a887 [TCP]: Don't apply FIN exception to full TSO segments.
Signed-off-by: John Heffner <jheffner@psc.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-02-08 12:38:51 -08:00
David S. Miller e89862f4c5 [TCP]: Restore SKB socket owner setting in tcp_transmit_skb().
Revert 931731123a

We can't elide the skb_set_owner_w() here because things like certain
netfilter targets (such as owner MATCH) need a socket to be set on the
SKB for correct operation.

Thanks to Jan Engelhardt and other netfilter list members for
pointing this out.

Signed-off-by: David S. Miller <davem@davemloft.net>
2007-01-26 01:04:55 -08:00
Jarek Poplawski 52d570aabe [TCP]: rare bad TCP checksum with 2.6.19
The patch "Replace CHECKSUM_HW by CHECKSUM_PARTIAL/CHECKSUM_COMPLETE"
changed to unconditional copying of ip_summed field from collapsed
skb. This patch reverts this change.

The majority of substantial work including heavy testing
and diagnosing by: Michael Tokarev <mjt@tls.msk.ru>
Possible reasons pointed by: Herbert Xu and Patrick McHardy.

Signed-off-by: Jarek Poplawski <jarkao2@o2.pl>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-01-23 22:07:12 -08:00
YOSHIFUJI Hideaki cfb6eeb4c8 [TCP]: MD5 Signature Option (RFC2385) support.
Based on implementation by Rick Payne.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-12-02 21:22:39 -08:00
Gerrit Renker b9df3cb8cf [TCP/DCCP]: Introduce net_xmit_eval
Throughout the TCP/DCCP (and tunnelling) code, it often happens that the
return code of a transmit function needs to be tested against NET_XMIT_CN
which is a value that does not indicate a strict error condition.

This patch uses a macro for these recurring situations which is consistent
with the already existing macro net_xmit_errno, saving on duplicated code.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
2006-12-02 21:22:27 -08:00
David S. Miller 931731123a [TCP]: Don't set SKB owner in tcp_transmit_skb().
The data itself is already charged to the SKB, doing
the skb_set_owner_w() just generates a lot of noise and
extra atomics we don't really need.

Lmbench improvements on lat_tcp are minimal:

before:
TCP latency using localhost: 23.2701 microseconds
TCP latency using localhost: 23.1994 microseconds
TCP latency using localhost: 23.2257 microseconds

after:
TCP latency using localhost: 22.8380 microseconds
TCP latency using localhost: 22.9465 microseconds
TCP latency using localhost: 22.8462 microseconds

Signed-off-by: David S. Miller <davem@davemloft.net>
2006-12-02 21:21:52 -08:00
John Heffner ae8064ac32 [TCP]: Bound TSO defer time
This patch limits the amount of time you will defer sending a TSO segment
to less than two clock ticks, or the time between two acks, whichever is
longer.

On slow links, deferring causes significant bursts.  See attached plots,
which show RTT through a 1 Mbps link with a 100 ms RTT and ~100 ms queue
for (a) non-TSO, (b) currnet TSO, and (c) patched TSO.  This burstiness
causes significant jitter, tends to overflow queues early (bad for short
queues), and makes delay-based congestion control more difficult.

Deferring by a couple clock ticks I believe will have a relatively small
impact on performance.

Signed-off-by: John Heffner <jheffner@psc.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-10-18 20:36:48 -07:00
YOSHIFUJI Hideaki 496c98dff8 [NET]: Use hton{l,s}() for non-initializers.
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-10-11 23:59:56 -07:00
Al Viro df7a3b07c2 [TCP] net/ipv4/tcp_output.c: trivial annotations
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-09-28 18:02:20 -07:00
Brian Haley ab32ea5d8a [NET/IPV4/IPV6]: Change some sysctl variables to __read_mostly
Change net/core, ipv4 and ipv6 sysctl variables to __read_mostly.

Couldn't actually measure any performance increase while testing (.3%
I consider noise), but seems like the right thing to do.

Signed-off-by: Brian Haley <brian.haley@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-09-22 14:55:03 -07:00
Patrick McHardy 84fa7933a3 [NET]: Replace CHECKSUM_HW by CHECKSUM_PARTIAL/CHECKSUM_COMPLETE
Replace CHECKSUM_HW by CHECKSUM_PARTIAL (for outgoing packets, whose
checksum still needs to be completed) and CHECKSUM_COMPLETE (for
incoming packets, device supplied full checksum).

Patch originally from Herbert Xu, updated by myself for 2.6.18-rc3.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-09-22 14:53:53 -07:00
Stephen Hemminger 316c1592be [TCP]: Limit window scaling if window is clamped.
This small change allows for easy per-route workarounds for broken hosts or
middleboxes that are not compliant with TCP standards for window scaling.
Rather than having to turn off window scaling globally. This patch allows
reducing or disabling window scaling if window clamp is present.

Example: Mark Lord reported a problem with 2.6.17 kernel being unable to
access http://www.everymac.com

# ip route add 216.145.246.23/32 via 10.8.0.1 window 65535

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-08-22 14:33:57 -07:00
Wei Yongjun bd37a08859 [TCP]: SNMPv2 tcpOutSegs counter error
Do not count retransmitted segments.

Signed-off-by: Wei Yongjun <yjwei@nanjing-fnst.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-08-07 21:04:15 -07:00
Herbert Xu bcd7611117 [NET]: Generalise TSO-specific bits from skb_setup_caps
This patch generalises the TSO-specific bits from sk_setup_caps by adding
the sk_gso_type member to struct sock.  This makes sk_setup_caps generic
so that it can be used by TCPv6 or UFO.

The only catch is that whoever uses this must provide a GSO implementation
for their protocol which I think is a fair deal :) For now UFO continues to
live without a GSO implementation which is OK since it doesn't use the sock
caps field at the moment.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-06-30 14:12:08 -07:00
Michael Chan b0da853703 [NET]: Add ECN support for TSO
In the current TSO implementation, NETIF_F_TSO and ECN cannot be
turned on together in a TCP connection.  The problem is that most
hardware that supports TSO does not handle CWR correctly if it is set
in the TSO packet.  Correct handling requires CWR to be set in the
first packet only if it is set in the TSO header.

This patch adds the ability to turn on NETIF_F_TSO and ECN using
GSO if necessary to handle TSO packets with CWR set.  Hardware
that handles CWR correctly can turn on NETIF_F_TSO_ECN in the dev->
features flag.

All TSO packets with CWR set will have the SKB_GSO_TCPV4_ECN set.  If
the output device does not have the NETIF_F_TSO_ECN feature set, GSO
will split the packet up correctly with CWR only set in the first
segment.

With help from Herbert Xu <herbert@gondor.apana.org.au>.

Since ECN can always be enabled with TSO, the SOCK_NO_LARGESEND sock
flag is completely removed.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-06-29 16:58:08 -07:00
Herbert Xu 7967168cef [NET]: Merge TSO/UFO fields in sk_buff
Having separate fields in sk_buff for TSO/UFO (tso_size/ufo_size) is not
going to scale if we add any more segmentation methods (e.g., DCCP).  So
let's merge them.

They were used to tell the protocol of a packet.  This function has been
subsumed by the new gso_type field.  This is essentially a set of netdev
feature bits (shifted by 16 bits) that are required to process a specific
skb.  As such it's easy to tell whether a given device can process a GSO
skb: you just have to and the gso_type field and the netdev's features
field.

I've made gso_type a conjunction.  The idea is that you have a base type
(e.g., SKB_GSO_TCPV4) that can be modified further to support new features.
For example, if we add a hardware TSO type that supports ECN, they would
declare NETIF_F_TSO | NETIF_F_TSO_ECN.  All TSO packets with CWR set would
have a gso_type of SKB_GSO_TCPV4 | SKB_GSO_TCPV4_ECN while all other TSO
packets would be SKB_GSO_TCPV4.  This means that only the CWR packets need
to be emulated in software.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-06-23 02:07:29 -07:00
David S. Miller 35089bb203 [TCP]: Add tcp_slow_start_after_idle sysctl.
A lot of people have asked for a way to disable tcp_cwnd_restart(),
and it seems reasonable to add a sysctl to do that.

Signed-off-by: David S. Miller <davem@davemloft.net>
2006-06-17 21:30:53 -07:00
Herbert Xu ~{PmVHI~} f291196979 [TCP]: Avoid skb_pull if possible when trimming head
Trimming the head of an skb by calling skb_pull can cause the packet
to become unaligned if the length pulled is odd.  Since the length is
entirely arbitrary for a FIN packet carrying data, this is actually
quite common.

Unaligned data is not the end of the world, but we should avoid it if
it's easily done.  In this case it is trivial.  Since we're discarding
all of the head data it doesn't matter whether we move skb->data forward
or back.

However, it is still possible to have unaligned skb->data in general.
So network drivers should be prepared to handle it instead of crashing.

This patch also adds an unlikely marking on len < headlen since partial
ACKs on head data are extremely rare in the wild.  As the return value
of __pskb_trim_head is no longer ever NULL that has been removed.

Signed-off-by: Herbert Xu ~{PmV>HI~} <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-06-05 15:03:37 -07:00
Hua Zhong 83de47cd0c [TCP]: Fix unlikely usage in tcp_transmit_skb()
The following unlikely should be replaced by likely because the
condition happens every time unless there is a hard error to transmit
a packet.

Signed-off-by: Hua Zhong <hzhong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-04-29 18:33:19 -07:00
Herbert Xu b60b49ea6a [TCP]: Account skb overhead in tcp_fragment
Make sure that we get the full sizeof(struct sk_buff)
plus the data size accounted for in skb->truesize.

This will create invariants that will allow adding
assertion checks on skb->truesize.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-04-19 21:35:00 -07:00
Herbert Xu ef5cb9738b [TCP]: Fix truesize underflow
There is a problem with the TSO packet trimming code.  The cause of
this lies in the tcp_fragment() function.

When we allocate a fragment for a completely non-linear packet the
truesize is calculated for a payload length of zero.  This means that
truesize could in fact be less than the real payload length.

When that happens the TSO packet trimming can cause truesize to become
negative.  This in turn can cause sk_forward_alloc to be -n * PAGE_SIZE
which would trigger the warning.

I've copied the code DaveM used in tso_fragment which should work here.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-04-18 15:57:49 -07:00
Adrian Bunk 6c97e72a16 [IPV4]: Possible cleanups.
This patch contains the following possible cleanups:
- make the following needlessly global function static:
  - arp.c: arp_rcv()
- remove the following unused EXPORT_SYMBOL's:
  - devinet.c: devinet_ioctl
  - fib_frontend.c: ip_rt_ioctl
  - inet_hashtables.c: inet_bind_bucket_create
  - inet_hashtables.c: inet_bind_hash
  - tcp_input.c: sysctl_tcp_abc
  - tcp_ipv4.c: sysctl_tcp_tw_reuse
  - tcp_output.c: sysctl_tcp_mtu_probing
  - tcp_output.c: sysctl_tcp_base_mss

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-04-14 15:00:20 -07:00
Rick Jones 15d99e02ba [TCP]: sysctl to allow TCP window > 32767 sans wscale
Back in the dark ages, we had to be conservative and only allow 15-bit
window fields if the window scale option was not negotiated.  Some
ancient stacks used a signed 16-bit quantity for the window field of
the TCP header and would get confused.

Those days are long gone, so we can use the full 16-bits by default
now.

There is a sysctl added so that we can still interact with such old
stacks

Signed-off-by: Rick Jones <rick.jones2@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-03-20 22:40:29 -08:00
John Heffner 0e7b13685f [TCP] mtu probing: move tcp-specific data out of inet_connection_sock
This moves some TCP-specific MTU probing state out of
inet_connection_sock back to tcp_sock.

Signed-off-by: John Heffner <jheffner@psc.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-03-20 21:32:58 -08:00
John Heffner 5d424d5a67 [TCP]: MTU probing
Implementation of packetization layer path mtu discovery for TCP, based on
the internet-draft currently found at
<http://www.ietf.org/internet-drafts/draft-ietf-pmtud-method-05.txt>.

Signed-off-by: John Heffner <jheffner@psc.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-03-20 17:53:41 -08:00
David S. Miller ba244fe900 [TCP]: Fix tcp_tso_should_defer() when limit>=65536
That's >= a full sized TSO frame, so we should always
return 0 in that case.

Based upon a report and initial patch from Lachlan
Andrew, final patch suggested by Herbert Xu.

Signed-off-by: David S. Miller <davem@davemloft.net>
2006-03-11 18:51:49 -08:00
Stephen Hemminger 40efc6fa17 [TCP]: less inline's
TCP inline usage cleanup:
 * get rid of inline in several places
 * replace __inline__ with inline where possible
 * move functions used in one file out of tcp.h
 * let compiler decide on used once cases

On x86_64: 
   text	   data	    bss	    dec	    hex	filename
3594701	 648348	 567400	4810449	 4966d1	vmlinux.orig
3593133	 648580	 567400	4809113	 496199	vmlinux

On sparc64:
   text	   data	    bss	    dec	    hex	filename
2538278	 406152	 530392	3474822	 350586	vmlinux.ORIG
2536382	 406384	 530392	3473158	 34ff06	vmlinux

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-01-03 16:03:49 -08:00
Arnaldo Carvalho de Melo d83d8461f9 [IP_SOCKGLUE]: Remove most of the tcp specific calls
As DCCP needs to be called in the same spots.

Now we have a member in inet_sock (is_icsk), set at sock creation time from
struct inet_protosw->flags (if INET_PROTOSW_ICSK is set, like for TCP and
DCCP) to see if a struct sock instance is a inet_connection_sock for places
like the ones in ip_sockglue.c (v4 and v6) where we previously were looking if
sk_type was SOCK_STREAM, that is insufficient because we now use the same code
for DCCP, that has sk_type SOCK_DCCP.

Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-01-03 13:10:58 -08:00
Arnaldo Carvalho de Melo 8292a17a39 [ICSK]: Rename struct tcp_func to struct inet_connection_sock_af_ops
And move it to struct inet_connection_sock. DCCP will use it in the
upcoming changesets.

Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-01-03 13:10:38 -08:00
David S. Miller dfb4b9dceb [TCP] Vegas: timestamp before clone
We have to store the congestion control timestamp on the SKB before we
clone it, not after.  Else we get no timestamping information at all.

tcp_transmit_skb() has been reworked so that we can do the timestamp
still in one spot, instead of at all the call sites.

Problem discovered, and initial fix, from Tom Young
<tyo@ee.unimelb.edu.au>.

Signed-off-by: David S. Miller <davem@davemloft.net>
2005-12-06 16:24:52 -08:00
Stephen Hemminger 6a438bbe68 [TCP]: speed up SACK processing
Use "hints" to speed up the SACK processing. Various forms 
of this have been used by TCP developers (Web100, STCP, BIC)
to avoid the 2x linear search of outstanding segments.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-11-10 17:14:59 -08:00
Stephen Hemminger caa20d9abe [TCP]: spelling fixes
Minor spelling fixes for TCP code.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-11-10 17:13:47 -08:00
Stephen Hemminger f4805eded7 [TCP]: fix congestion window update when using TSO deferal
TCP peformance with TSO over networks with delay is awful.
On a 100Mbit link with 150ms delay, we get 4Mbits/sec with TSO and
50Mbits/sec without TSO.

The problem is with TSO, we intentionally do not keep the maximum
number of packets in flight to fill the window, we hold out to until 
we can send a MSS chunk. But, we also don't update the congestion window 
unless we have filled, as per RFC2861.

This patch replaces the check for the congestion window being full
with something smarter that accounts for TSO.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-11-10 16:53:30 -08:00
Herbert Xu b2cc99f04c [TCP] Allow len == skb->len in tcp_fragment
It is legitimate to call tcp_fragment with len == skb->len since
that is done for FIN packets and the FIN flag counts as one byte.
So we should only check for the len > skb->len case.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
2005-10-20 17:13:13 -02:00
Herbert Xu 046d20b739 [TCP]: Ratelimit debugging warning.
Better safe than sorry.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-10-13 14:42:24 -07:00
Herbert Xu 9ff5c59ce2 [TCP]: Add code to help track down "BUG at net/ipv4/tcp_output.c:438!"
This is the second report of this bug.  Unfortunately the first
reporter hasn't been able to reproduce it since to provide more
debugging info.

So let's apply this patch for 2.6.14 to

1) Make this non-fatal.
2) Provide the info we need to track it down.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-10-12 15:59:39 -07:00
Al Viro dd0fc66fb3 [PATCH] gfp flags annotations - part 1
- added typedef unsigned int __nocast gfp_t;

 - replaced __nocast uses for gfp flags with gfp_t - it gives exactly
   the same warnings as far as sparse is concerned, doesn't change
   generated code (from gcc point of view we replaced unsigned int with
   typedef) and documents what's going on far better.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-08 15:00:57 -07:00
David S. Miller 01ff367e62 [TCP]: Revert 6b251858d3
But retain the comment fix.

Alexey Kuznetsov has explained the situation as follows:

--------------------

I think the fix is incorrect. Look, the RFC function init_cwnd(mss) is
not continuous: f.e. for mss=1095 it needs initial window 1095*4, but
for mss=1096 it is 1096*3. We do not know exactly what mss sender used
for calculations. If we advertised 1096 (and calculate initial window
3*1096), the sender could limit it to some value < 1096 and then it
will need window his_mss*4 > 3*1096 to send initial burst.

See?

So, the honest function for inital rcv_wnd derived from
tcp_init_cwnd() is:

	init_rcv_wnd(mss)=
	  min { init_cwnd(mss1)*mss1 for mss1 <= mss }

It is something sort of:

	if (mss < 1096)
		return mss*4;
	if (mss < 1096*2)
		return 1096*4;
	return mss*2;

(I just scrablled a graph of piece of paper, it is difficult to see or
to explain without this)

I selected it differently giving more window than it is strictly
required.  Initial receive window must be large enough to allow sender
following to the rfc (or just setting initial cwnd to 2) to send
initial burst.  But besides that it is arbitrary, so I decided to give
slack space of one segment.

Actually, the logic was:

If mss is low/normal (<=ethernet), set window to receive more than
initial burst allowed by rfc under the worst conditions
i.e. mss*4. This gives slack space of 1 segment for ethernet frames.

For msses slighlty more than ethernet frame, take 3. Try to give slack
space of 1 frame again.

If mss is huge, force 2*mss. No slack space.

Value 1460*3 is really confusing. Minimal one is 1096*2, but besides
that it is an arbitrary value. It was meant to be ~4096. 1460*3 is
just the magic number from RFC, 1460*3 = 1095*4 is the magic :-), so
that I guess hands typed this themselves.

--------------------

Signed-off-by: David S. Miller <davem@davemloft.net>
2005-09-29 17:07:20 -07:00
David S. Miller 6b251858d3 [TCP]: Fix init_cwnd calculations in tcp_select_initial_window()
Match it up to what RFC2414 really specifies.
Noticed by Rick Jones.

Signed-off-by: David S. Miller <davem@davemloft.net>
2005-09-28 16:31:48 -07:00
Herbert Xu 83ca28befc [TCP]: Adjust Reno SACK estimate in tcp_fragment
Since the introduction of TSO pcount a year ago, it has been possible
for tcp_fragment() to cause packets_out to decrease.  Prior to that,
tcp_retrans_try_collapse() was the only way for that to happen on the
retransmission path.

When this happens with Reno, it is possible for sasked_out to become
invalid because it is only an estimate and not tied to any particular
packet on the retransmission queue.

Therefore we need to adjust sacked_out as well as left_out in the Reno
case.  The following patch does exactly that.

This bug is pretty difficult to trigger in practice though since you
need a SACKless peer with a retransmission that occurs just as the
cached MTU value expires.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-09-22 23:32:56 -07:00
Herbert Xu e14c3caf60 [TCP]: Handle SACK'd packets properly in tcp_fragment().
The problem is that we're now calling tcp_fragment() in a context
where the packets might be marked as SACKED_ACKED or SACKED_RETRANS.
This was not possible before as you never retransmitted packets that
are so marked.

Because of this, we need to adjust sacked_out and retrans_out in
tcp_fragment().  This is exactly what the following patch does.

We also need to preserve the SACKED_ACKED/SACKED_RETRANS marking
if they exist.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-09-19 18:18:38 -07:00
Herbert Xu 3c05d92ed4 [TCP]: Compute in_sacked properly when we split up a TSO frame.
The problem is that the SACK fragmenting code may incorrectly call
tcp_fragment() with a length larger than the skb->len.  This happens
when the skb on the transmit queue completely falls to the LHS of the
SACK.

And add a BUG() check to tcp_fragment() so we can spot this kind of
error more quickly in the future.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-09-14 20:50:35 -07:00
Herbert Xu e130af5dab [TCP]: Fix double adjustment of tp->{lost,left}_out in tcp_fragment().
There is an extra left_out/lost_out adjustment in tcp_fragment which
means that the lost_out accounting is always wrong.  This patch removes
that chunk of code.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-09-10 17:19:09 -07:00
Herbert Xu cf0b450cd5 [TCP]: Fix off by one in tcp_fragment() "already sent" test.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-09-08 15:10:52 -07:00
David S. Miller 6475be16fd [TCP]: Keep TSO enabled even during loss events.
All we need to do is resegment the queue so that
we record SACK information accurately.  The edges
of the SACK blocks guide our resegmenting decisions.

With help from Herbert Xu.

Signed-off-by: David S. Miller <davem@davemloft.net>
2005-09-01 22:47:01 -07:00
David S. Miller d179cd1292 [NET]: Implement SKB fast cloning.
Protocols that make extensive use of SKB cloning,
for example TCP, eat at least 2 allocations per
packet sent as a result.

To cut the kmalloc() count in half, we implement
a pre-allocation scheme wherein we allocate
2 sk_buff objects in advance, then use a simple
reference count to free up the memory at the
correct time.

Based upon an initial patch by Thomas Graf and
suggestions from Herbert Xu.

Signed-off-by: David S. Miller <davem@davemloft.net>
2005-08-29 16:01:54 -07:00
Patrick McHardy a61bbcf28a [NET]: Store skb->timestamp as offset to a base timestamp
Reduces skb size by 8 bytes on 64-bit.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-08-29 15:58:24 -07:00
Arnaldo Carvalho de Melo 6687e988d9 [ICSK]: Move TCP congestion avoidance members to icsk
This changeset basically moves tcp_sk()->{ca_ops,ca_state,etc} to inet_csk(),
minimal renaming/moving done in this changeset to ease review.

Most of it is just changes of struct tcp_sock * to struct sock * parameters.

With this we move to a state closer to two interesting goals:

1. Generalisation of net/ipv4/tcp_diag.c, becoming inet_diag.c, being used
   for any INET transport protocol that has struct inet_hashinfo and are
   derived from struct inet_connection_sock. Keeps the userspace API, that will
   just not display DCCP sockets, while newer versions of tools can support
   DCCP.

2. INET generic transport pluggable Congestion Avoidance infrastructure, using
   the current TCP CA infrastructure with DCCP.

Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-08-29 15:56:18 -07:00
Arnaldo Carvalho de Melo 3f421baa47 [NET]: Just move the inet_connection_sock function from tcp sources
Completing the previous changeset, this also generalises tcp_v4_synq_add,
renaming it to inet_csk_reqsk_queue_hash_add, already geing used in the
DCCP tree, which I plan to merge RSN.

Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-08-29 15:49:14 -07:00
Arnaldo Carvalho de Melo 463c84b97f [NET]: Introduce inet_connection_sock
This creates struct inet_connection_sock, moving members out of struct
tcp_sock that are shareable with other INET connection oriented
protocols, such as DCCP, that in my private tree already uses most of
these members.

The functions that operate on these members were renamed, using a
inet_csk_ prefix while not being moved yet to a new file, so as to
ease the review of these changes.

Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-08-29 15:43:19 -07:00
David S. Miller 8728b834b2 [NET]: Kill skb->list
Remove the "list" member of struct sk_buff, as it is entirely
redundant.  All SKB list removal callers know which list the
SKB is on, so storing this in sk_buff does nothing other than
taking up some space.

Two tricky bits were SCTP, which I took care of, and two ATM
drivers which Francois Romieu <romieu@fr.zoreil.com> fixed
up.

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
2005-08-29 15:31:14 -07:00
Dmitry Yusupov 14869c3886 [TCP]: Do TSO deferral even if tail SKB can go out now.
If the tail SKB fits into the window, it is still
benefitical to defer until the goal percentage of
the window is available.  This give the application
time to feed more data into the send queue and thus
results in larger TSO frames going out.

Patch from Dmitry Yusupov <dima@neterion.com>.

Signed-off-by: David S. Miller <davem@davemloft.net>
2005-08-23 10:09:27 -07:00
Herbert Xu c8ac377464 [TCP]: Fix bug #5070: kernel BUG at net/ipv4/tcp_output.c:864
1) We send out a normal sized packet with TSO on to start off.
2) ICMP is received indicating a smaller MTU.
3) We send the current sk_send_head which needs to be fragmented
since it was created before the ICMP event.  The first fragment
is then sent out.

At this point the remaining fragment is allocated by tcp_fragment.
However, its size is padded to fit the L1 cache-line size therefore
creating tail-room up to 124 bytes long.

This fragment will also be sitting at sk_send_head.

4) tcp_sendmsg is called again and it stores data in the tail-room of
of the fragment.
5) tcp_push_one is called by tcp_sendmsg which then calls tso_fragment
since the packet as a whole exceeds the MTU.

At this point we have a packet that has data in the head area being
fed to tso_fragment which bombs out.

My take on this is that we shouldn't ever call tcp_fragment on a TSO
socket for a packet that is yet to be transmitted since this creates
a packet on sk_send_head that cannot be extended.

So here is a patch to change it so that tso_fragment is always used
in this case.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-08-16 20:43:40 -07:00
Herbert Xu b5da623ae9 [TCP]: Adjust {p,f}ackets_out correctly in tcp_retransmit_skb()
Well I've only found one potential cause for the assertion
failure in tcp_mark_head_lost.  First of all, this can only
occur if cnt > 1 since tp->packets_out is never zero here.
If it did hit zero we'd have much bigger problems.

So cnt is equal to fackets_out - reordering.  Normally
fackets_out is less than packets_out.  The only reason
I've found that might cause fackets_out to exceed packets_out
is if tcp_fragment is called from tcp_retransmit_skb with a
TSO skb and the current MSS is greater than the MSS stored
in the TSO skb.  This might occur as the result of an expiring
dst entry.

In that case, packets_out may decrease (line 1380-1381 in
tcp_output.c).  However, fackets_out is unchanged which means
that it may in fact exceed packets_out.

Previously tcp_retrans_try_collapse was the only place where
packets_out can go down and it takes care of this by decrementing
fackets_out.

So we should make sure that fackets_out is reduced by an appropriate
amount here as well.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-08-10 18:32:36 -07:00
Herbert Xu b68e9f8572 [PATCH] tcp: fix TSO cwnd caching bug
tcp_write_xmit caches the cwnd value indirectly in cwnd_quota.  When
tcp_transmit_skb reduces the cwnd because of tcp_enter_cwr, the cached
value becomes invalid.

This patch ensures that the cwnd value is always reread after each
tcp_transmit_skb call.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-08-04 21:43:14 -07:00
David S. Miller 846998ae87 [PATCH] tcp: fix TSO sizing bugs
MSS changes can be lost since we preemptively initialize the tso_segs count
for an SKB before we %100 commit to sending it out.

So, by the time we send it out, the tso_size information can be stale due
to PMTU events.  This mucks up all of the logic in our send engine, and can
even result in the BUG() triggering in tcp_tso_should_defer().

Another problem we have is that we're storing the tp->mss_cache, not the
SACK block normalized MSS, as the tso_size.  That's wrong too.

Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-08-04 21:43:14 -07:00
Victor Fusco 86a76caf87 [NET]: Fix sparse warnings
From: Victor Fusco <victor@cetuc.puc-rio.br>

Fix the sparse warning "implicit cast to nocast type"

Signed-off-by: Victor Fusco <victor@cetuc.puc-rio.br>
Signed-off-by: Domen Puncer <domen@coderock.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-08 14:57:47 -07:00
David S. Miller 908a75c17a [TCP]: Never TSO defer under periods of congestion.
Congestion window recover after loss depends upon the fact
that if we have a full MSS sized frame at the head of the
send queue, we will send it.  TSO deferral can defeat the
ACK clocking necessary to exit cleanly from recovery.

Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-05 15:43:58 -07:00
David S. Miller c1b4a7e695 [TCP]: Move to new TSO segmenting scheme.
Make TSO segment transmit size decisions at send time not earlier.

The basic scheme is that we try to build as large a TSO frame as
possible when pulling in the user data, but the size of the TSO frame
output to the card is determined at transmit time.

This is guided by tp->xmit_size_goal.  It is always set to a multiple
of MSS and tells sendmsg/sendpage how large an SKB to try and build.

Later, tcp_write_xmit() and tcp_push_one() chop up the packet if
necessary and conditions warrant.  These routines can also decide to
"defer" in order to wait for more ACKs to arrive and thus allow larger
TSO frames to be emitted.

A general observation is that TSO elongates the pipe, thus requiring a
larger congestion window and larger buffering especially at the sender
side.  Therefore, it is important that applications 1) get a large
enough socket send buffer (this is accomplished by our dynamic send
buffer expansion code) 2) do large enough writes.

Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-05 15:24:38 -07:00
David S. Miller aa93466bdf [TCP]: Eliminate redundant computations in tcp_write_xmit().
tcp_snd_test() is run for every packet output by a single
call to tcp_write_xmit(), but this is not necessary.

For one, the congestion window space needs to only be
calculated one time, then used throughout the duration
of the loop.

This cleanup also makes experimenting with different TSO
packetization schemes much easier.

Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-05 15:20:09 -07:00
David S. Miller 7f4dd0a943 [TCP]: Break out tcp_snd_test() into it's constituent parts.
tcp_snd_test() does several different things, use inline
functions to express this more clearly.

1) It initializes the TSO count of SKB, if necessary.
2) It performs the Nagle test.
3) It makes sure the congestion window is adhered to.
4) It makes sure SKB fits into the send window.

This cleanup also sets things up so that things like the
available packets in the congestion window does not need
to be calculated multiple times by packet sending loops
such as tcp_write_xmit().
    
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-05 15:19:54 -07:00
David S. Miller 55c97f3e99 [TCP]: Fix __tcp_push_pending_frames() 'nonagle' handling.
'nonagle' should be passed to the tcp_snd_test() function
as 'TCP_NAGLE_PUSH' if we are checking an SKB not at the
tail of the write_queue.  This is because Nagle does not
apply to such frames since we cannot possibly tack more
data onto them.

However, while doing this __tcp_push_pending_frames() makes
all of the packets in the write_queue use this modified
'nonagle' value.

Fix the bug and simplify this function by just calling
tcp_write_xmit() directly if sk_send_head is non-NULL.

As a result, we can now make tcp_data_snd_check() just call
tcp_push_pending_frames() instead of the specialized
__tcp_data_snd_check().

Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-05 15:19:38 -07:00
David S. Miller a2e2a59c93 [TCP]: Fix redundant calculations of tcp_current_mss()
tcp_write_xmit() uses tcp_current_mss(), but some of it's callers,
namely __tcp_push_pending_frames(), already has this value available
already.

While we're here, fix the "cur_mss" argument to be "unsigned int"
instead of plain "unsigned".

Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-05 15:19:23 -07:00
David S. Miller 92df7b518d [TCP]: tcp_write_xmit() tabbing cleanup
Put the main basic block of work at the top-level of
tabbing, and mark the TCP_CLOSE test with unlikely().

Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-05 15:19:06 -07:00
David S. Miller a762a98007 [TCP]: Kill extra cwnd validate in __tcp_push_pending_frames().
The tcp_cwnd_validate() function should only be invoked
if we actually send some frames, yet __tcp_push_pending_frames()
will always invoke it.  tcp_write_xmit() does the call for us,
so the call here can simply be removed.

Also, tcp_write_xmit() can be marked static.

Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-05 15:18:51 -07:00
David S. Miller f44b527177 [TCP]: Add missing skb_header_release() call to tcp_fragment().
When we add any new packet to the TCP socket write queue,
we must call skb_header_release() on it in order for the
TSO sharing checks in the drivers to work.

Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-05 15:18:34 -07:00
David S. Miller 84d3e7b957 [TCP]: Move __tcp_data_snd_check into tcp_output.c
It reimplements portions of tcp_snd_check(), so it
we move it to tcp_output.c we can consolidate it's
logic much easier in a later change.

Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-05 15:18:18 -07:00
David S. Miller f6302d1d78 [TCP]: Move send test logic out of net/tcp.h
This just moves the code into tcp_output.c, no code logic changes are
made by this patch.

Using this as a baseline, we can begin to untangle the mess of
comparisons for the Nagle test et al.  We will also be able to reduce
all of the redundant computation that occurs when outputting data
packets.

Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-05 15:18:03 -07:00
David S. Miller fc6415bcb0 [TCP]: Fix quick-ack decrementing with TSO.
On each packet output, we call tcp_dec_quickack_mode()
if the ACK flag is set.  It drops tp->ack.quick until
it hits zero, at which time we deflate the ATO value.

When doing TSO, we are emitting multiple packets with
ACK set, so we should decrement tp->ack.quick that many
segments.

Note that, unlike this case, tcp_enter_cwr() should not
take the tcp_skb_pcount(skb) into consideration.  That
function, one time, readjusts tp->snd_cwnd and moves
into TCP_CA_CWR state.

Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-05 15:17:45 -07:00
Stephen Hemminger 317a76f9a4 [TCP]: Add pluggable congestion control algorithm infrastructure.
Allow TCP to have multiple pluggable congestion control algorithms.
Algorithms are defined by a set of operations and can be built in
or modules.  The legacy "new RENO" algorithm is used as a starting
point and fallback.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-06-23 12:19:55 -07:00
Arnaldo Carvalho de Melo 60236fdd08 [NET] Rename open_request to request_sock
Ok, this one just renames some stuff to have a better namespace and to
dissassociate it from TCP:

struct open_request  -> struct request_sock
tcp_openreq_alloc    -> reqsk_alloc
tcp_openreq_free     -> reqsk_free
tcp_openreq_fastfree -> __reqsk_free

With this most of the infrastructure closely resembles a struct
sock methods subset.

Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-06-18 22:47:21 -07:00
Arnaldo Carvalho de Melo 2e6599cb89 [NET] Generalise TCP's struct open_request minisock infrastructure
Kept this first changeset minimal, without changing existing names to
ease peer review.

Basicaly tcp_openreq_alloc now receives the or_calltable, that in turn
has two new members:

->slab, that replaces tcp_openreq_cachep
->obj_size, to inform the size of the openreq descendant for
  a specific protocol

The protocol specific fields in struct open_request were moved to a
class hierarchy, with the things that are common to all connection
oriented PF_INET protocols in struct inet_request_sock, the TCP ones
in tcp_request_sock, that is an inet_request_sock, that is an
open_request.

I.e. this uses the same approach used for the struct sock class
hierarchy, with sk_prot indicating if the protocol wants to use the
open_request infrastructure by filling in sk_prot->rsk_prot with an
or_calltable.

Results? Performance is improved and TCP v4 now uses only 64 bytes per
open request minisock, down from 96 without this patch :-)

Next changeset will rename some of the structs, fields and functions
mentioned above, struct or_calltable is way unclear, better name it
struct request_sock_ops, s/struct open_request/struct request_sock/g,
etc.

Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-06-18 22:46:52 -07:00
Jesper Juhl 02c30a84e6 [PATCH] update Ross Biro bouncing email address
Ross moved.  Remove the bad email address so people will find the correct
one in ./CREDITS.

Signed-off-by: Jesper Juhl <juhl-lkml@dif.dk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-05-05 16:36:49 -07:00
David S. Miller d5ac99a648 [TCP]: skb pcount with MTU discovery
The problem is that when doing MTU discovery, the too-large segments in
the write queue will be calculated as having a pcount of >1.  When
tcp_write_xmit() is trying to send, tcp_snd_test() fails the cwnd test
when pcount > cwnd.

The segments are eventually transmitted one at a time by keepalive, but
this can take a long time.

This patch checks if TSO is enabled when setting pcount.

Signed-off-by: John Heffner <jheffner@psc.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-04-24 19:12:33 -07:00
Linus Torvalds 1da177e4c3 Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00