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2008-08-27tcp: fix tcp header size miscalculation when window scale is unusedPhilip Love
The size of the TCP header is miscalculated when the window scale ends up being 0. Additionally, this can be induced by sending a SYN to a passive open port with a window scale option with value 0. Signed-off-by: Philip Love <love_phil@emc.com> Signed-off-by: Adam Langley <agl@imperialviolet.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-21tcp: Fix bitmask test in tcp_syn_options()David S. Miller
As reported by Alexey Dobriyan: CHECK net/ipv4/tcp_output.c net/ipv4/tcp_output.c:475:7: warning: dubious: !x & y And sparse is damn right! if (unlikely(!OPTION_TS & opts->options)) ^^^ size += TCPOLEN_SACKPERM_ALIGNED; OPTION_TS is (1 << 1), so condition will never trigger. Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-19tcp: options clean upAdam Langley
This should fix the following bugs: * Connections with MD5 signatures produce invalid packets whenever SACK options are included * MD5 signatures are counted twice in the MSS calculations Behaviour changes: * A SYN with MD5 + SACK + TS elicits a SYNACK with MD5 + SACK This is because we can't fit any SACK blocks in a packet with MD5 + TS options. There was discussion about disabling SACK rather than TS in order to fit in better with old, buggy kernels, but that was deemed to be unnecessary. * SYNs with MD5 don't include a TS option See above. Additionally, it removes a bunch of duplicated logic for calculating options, which should help avoid these sort of issues in the future. Signed-off-by: Adam Langley <agl@imperialviolet.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-19tcp: Fix MD5 signatures for non-linear skbsAdam Langley
Currently, the MD5 code assumes that the SKBs are linear and, in the case that they aren't, happily goes off and hashes off the end of the SKB and into random memory. Reported by Stephen Hemminger in [1]. Advice thanks to Stephen and Evgeniy Polyakov. Also includes a couple of missed route_caps from Stephen's patch in [2]. [1] http://marc.info/?l=linux-netdev&m=121445989106145&w=2 [2] http://marc.info/?l=linux-netdev&m=121459157816964&w=2 Signed-off-by: Adam Langley <agl@imperialviolet.org> Acked-by: Stephen Hemminger <shemminger@vyatta.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-16mib: add net to NET_INC_STATS_BHPavel Emelyanov
Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-16mib: add net to NET_INC_STATSPavel Emelyanov
Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-16mib: add net to TCP_INC_STATSPavel Emelyanov
Fortunately (almost) all the TCP code has a sock to get the net from :) Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-03tcp: de-bloat a bit with factoring NET_INC_STATS_BH outPavel Emelyanov
There are some places in TCP that select one MIB index to bump snmp statistics like this: if (<something>) NET_INC_STATS_BH(<some_id>); else if (<something_else>) NET_INC_STATS_BH(<some_other_id>); ... else NET_INC_STATS_BH(<default_id>); or in a more tricky but still similar way. On the other hand, this NET_INC_STATS_BH is a camouflaged increment of percpu variable, which is not that small. Factoring those cases out de-bloats 235 bytes on non-preemptible i386 config and drives parts of the code into 80 columns. add/remove: 0/0 grow/shrink: 0/7 up/down: 0/-235 (-235) function old new delta tcp_fastretrans_alert 1437 1424 -13 tcp_dsack_set 137 124 -13 tcp_xmit_retransmit_queue 690 676 -14 tcp_try_undo_recovery 283 265 -18 tcp_sacktag_write_queue 1550 1515 -35 tcp_update_reordering 162 106 -56 tcp_retransmit_timer 990 904 -86 Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-06-11Merge branch 'net-next-2.6-misc-20080612a' of ↵David S. Miller
git://git.linux-ipv6.org/gitroot/yoshfuji/linux-2.6-next
2008-06-11net: remove CVS keywordsAdrian Bunk
This patch removes CVS keywords that weren't updated for a long time from comments. Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-06-12tcp md5sig: Remove redundant protocol argument.YOSHIFUJI Hideaki
Protocol is always TCP, so remove useless protocol argument. Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
2008-06-04tcp: Increment OUTRSTS in tcp_send_active_reset()Sridhar Samudrala
TCP "resets sent" counter is not incremented when a TCP Reset is sent via tcp_send_active_reset(). Signed-off-by: Sridhar Samudrala <sri@us.ibm.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-05-21tcp: TCP connection times out if ICMP frag needed is delayedSridhar Samudrala
We are seeing an issue with TCP in handling an ICMP frag needed message that is received after net.ipv4.tcp_retries1 retransmits. The default value of retries1 is 3. So if the path mtu changes and ICMP frag needed is lost for the first 3 retransmits or if it gets delayed until 3 retransmits are done, TCP doesn't update MSS correctly and continues to retransmit the orginal message until it timesout after tcp_retries2 retransmits. I am seeing this issue even with the latest 2.6.25.4 kernel. In tcp_retransmit_timer(), when retransmits counter exceeds tcp_retries1 value, the dst cache entry of the socket is reset. At this time, if we receive an ICMP frag needed message, the dst entry gets updated with the new MTU, but the TCP sockets dst_cache entry remains NULL. So the next time when we try to retransmit after the ICMP frag needed is received, tcp_retransmit_skb() gets called. Here the cur_mss value is calculated at the start of the routine with a NULL sk_dst_cache. Instead we should call tcp_current_mss after the rebuild_header that caches the dst entry with the updated mtu. Also the rebuild_header should be called before tcp_fragment so that skb is fragmented if the mss goes down. Signed-off-by: Sridhar Samudrala <sri@us.ibm.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-04-15[TCP]: Remove superflushious skb == write_queue_tail() checkIlpo Järvinen
Needed can only be more strict than what was checked by the earlier common case check for non-tail skbs, thus cwnd_len <= needed will never match in that case anyway. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-04-14Merge branch 'master' of ↵David S. Miller
master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 Conflicts: drivers/net/ehea/ehea_main.c drivers/net/wireless/iwlwifi/Kconfig drivers/net/wireless/rt2x00/rt61pci.c net/ipv4/inet_timewait_sock.c net/ipv6/raw.c net/mac80211/ieee80211_sta.c
2008-04-10[Syncookies]: Add support for TCP options via timestamps.Florian Westphal
Allow the use of SACK and window scaling when syncookies are used and the client supports tcp timestamps. Options are encoded into the timestamp sent in the syn-ack and restored from the timestamp echo when the ack is received. Based on earlier work by Glenn Griffin. This patch avoids increasing the size of structs by encoding TCP options into the least significant bits of the timestamp and by not using any 'timestamp offset'. The downside is that the timestamp sent in the packet after the synack will increase by several seconds. changes since v1: don't duplicate timestamp echo decoding function, put it into ipv4/syncookie.c and have ipv6/syncookies.c use it. Feedback from Glenn Griffin: fix line indented with spaces, kill redundant if () Reviewed-by: Hagen Paul Pfeifer <hagen@jauu.net> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-04-07[TCP]: tcp_simple_retransmit can cause S+LIlpo Järvinen
This fixes Bugzilla #10384 tcp_simple_retransmit does L increment without any checking whatsoever for overflowing S+L when Reno is in use. The simplest scenario I can currently think of is rather complex in practice (there might be some more straightforward cases though). Ie., if mss is reduced during mtu probing, it may end up marking everything lost and if some duplicate ACKs arrived prior to that sacked_out will be non-zero as well, leading to S+L > packets_out, tcp_clean_rtx_queue on the next cumulative ACK or tcp_fastretrans_alert on the next duplicate ACK will fix the S counter. More straightforward (but questionable) solution would be to just call tcp_reset_reno_sack() in tcp_simple_retransmit but it would negatively impact the probe's retransmission, ie., the retransmissions would not occur if some duplicate ACKs had arrived. So I had to add reno sacked_out reseting to CA_Loss state when the first cumulative ACK arrives (this stale sacked_out might actually be the explanation for the reports of left_out overflows in kernel prior to 2.6.23 and S+L overflow reports of 2.6.24). However, this alone won't be enough to fix kernel before 2.6.24 because it is building on top of the commit 1b6d427bb7e ([TCP]: Reduce sacked_out with reno when purging write_queue) to keep the sacked_out from overflowing. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Reported-by: Alessandro Suardi <alessandro.suardi@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-03-21[NET]: Add per-connection option to set max TSO frame sizePeter P Waskiewicz Jr
Update: My mailer ate one of Jarek's feedback mails... Fixed the parameter in netif_set_gso_max_size() to be u32, not u16. Fixed the whitespace issue due to a patch import botch. Changed the types from u32 to unsigned int to be more consistent with other variables in the area. Also brought the patch up to the latest net-2.6.26 tree. Update: Made gso_max_size container 32 bits, not 16. Moved the location of gso_max_size within netdev to be less hotpath. Made more consistent names between the sock and netdev layers, and added a define for the max GSO size. Update: Respun for net-2.6.26 tree. Update: changed max_gso_frame_size and sk_gso_max_size from signed to unsigned - thanks Stephen! This patch adds the ability for device drivers to control the size of the TSO frames being sent to them, per TCP connection. By setting the netdevice's gso_max_size value, the socket layer will set the GSO frame size based on that value. This will propogate into the TCP layer, and send TSO's of that size to the hardware. This can be desirable to help tune the bursty nature of TSO on a per-adapter basis, where one may have 1 GbE and 10 GbE devices coexisting in a system, one running multiqueue and the other not, etc. This can also be desirable for devices that cannot support full 64 KB TSO's, but still want to benefit from some level of segmentation offloading. Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-03-21Merge branch 'master' of ↵David S. Miller
git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6
2008-03-20[TCP]: Fix shrinking windows with window scalingPatrick McHardy
When selecting a new window, tcp_select_window() tries not to shrink the offered window by using the maximum of the remaining offered window size and the newly calculated window size. The newly calculated window size is always a multiple of the window scaling factor, the remaining window size however might not be since it depends on rcv_wup/rcv_nxt. This means we're effectively shrinking the window when scaling it down. The dump below shows the problem (scaling factor 2^7): - Window size of 557 (71296) is advertised, up to 3111907257: IP 172.2.2.3.33000 > 172.2.2.2.33000: . ack 3111835961 win 557 <...> - New window size of 514 (65792) is advertised, up to 3111907217, 40 bytes below the last end: IP 172.2.2.3.33000 > 172.2.2.2.33000: . 3113575668:3113577116(1448) ack 3111841425 win 514 <...> The number 40 results from downscaling the remaining window: 3111907257 - 3111841425 = 65832 65832 / 2^7 = 514 65832 % 2^7 = 40 If the sender uses up the entire window before it is shrunk, this can have chaotic effects on the connection. When sending ACKs, tcp_acceptable_seq() will notice that the window has been shrunk since tcp_wnd_end() is before tp->snd_nxt, which makes it choose tcp_wnd_end() as sequence number. This will fail the receivers checks in tcp_sequence() however since it is before it's tp->rcv_wup, making it respond with a dupack. If both sides are in this condition, this leads to a constant flood of ACKs until the connection times out. Make sure the window is never shrunk by aligning the remaining window to the window scaling factor. Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-03-18Merge branch 'master' of ↵David S. Miller
git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6 Conflicts: drivers/net/wireless/rt2x00/rt2x00dev.c net/8021q/vlan_dev.c
2008-03-11[TCP]: Prevent sending past receiver window with TSO (at last skb)Ilpo Järvinen
With TSO it was possible to send past the receiver window when the skb to be sent was the last in the write queue while the receiver window is the limiting factor. One can notice that there's a loophole in the tcp_mss_split_point that lacked a receiver window check for the tcp_write_queue_tail() if also cwnd was smaller than the full skb. Noticed by Thomas Gleixner <tglx@linutronix.de> in form of "Treason uncloaked! Peer ... shrinks window .... Repaired." messages (the peer didn't actually shrink its window as the message suggests, we had just sent something past it without a permission to do so). Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Tested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-03-04[TCP]: Add IPv6 support to TCP SYN cookiesGlenn Griffin
Updated to incorporate Eric's suggestion of using a per cpu buffer rather than allocating on the stack. Just a two line change, but will resend in it's entirety. Signed-off-by: Glenn Griffin <ggriffin.kernel@gmail.com> Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
2008-01-31[TCP]: Unexport sysctl_tcp_tso_win_divisorAdrian Bunk
This patch removes the no longer used EXPORT_SYMBOL(sysctl_tcp_tso_win_divisor). Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28[TCP]: Perform setting of common control fields in one placeIlpo Järvinen
In case of segments which are purely for control without any data (SYN/ACK/FIN/RST), many fields are set to common values in multiple places. i386 results: $ gcc --version gcc (GCC) 4.1.2 20070626 (Red Hat 4.1.2-13) $ codiff tcp_output.o.old tcp_output.o.new net/ipv4/tcp_output.c: tcp_xmit_probe_skb | -48 tcp_send_ack | -56 tcp_retransmit_skb | -79 tcp_connect | -43 tcp_send_active_reset | -35 tcp_make_synack | -42 tcp_send_fin | -48 7 functions changed, 351 bytes removed net/ipv4/tcp_output.c: tcp_init_nondata_skb | +90 1 function changed, 90 bytes added tcp_output.o.mid: 8 functions changed, 90 bytes added, 351 bytes removed, diff: -261 Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28[TCP]: Urgent parameter effect can be simplified.Ilpo Järvinen
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28[TCP]: Remove unnecessary local variableIlpo Järvinen
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28[TCP]: Code duplication removal, added tcp_bound_to_half_wnd()Ilpo Järvinen
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28[TCP]: cleanup tcp_{in,out}put.c styleIlpo Järvinen
These were manually selected from indent's results which as is are too noisy to be of any use without human reason. In addition, some extra newlines between function and its comment were removed too. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28[TCP]: reduce tcp_output's indentation levels a bitIlpo Järvinen
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28[TCP]: Remove TCPCB_URG & TCPCB_AT_TAIL as unnecessaryIlpo Järvinen
The snd_up check should be enough. I suspect this has been there to provide a minor optimization in clean_rtx_queue which used to have a small if (!->sacked) block which could skip snd_up check among the other work. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28[TCP]: Introduce tcp_wnd_end() to reduce line lengthsIlpo Järvinen
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28[TCP]: Rename update_send_head & include related increment to itIlpo Järvinen
There's very little need to have the packets_out incrementing in a separate function. Also name the combined function appropriately. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28[NET] CORE: Introducing new memory accounting interface.Hideo Aoki
This patch introduces new memory accounting functions for each network protocol. Most of them are renamed from memory accounting functions for stream protocols. At the same time, some stream memory accounting functions are removed since other functions do same thing. Renaming: sk_stream_free_skb() -> sk_wmem_free_skb() __sk_stream_mem_reclaim() -> __sk_mem_reclaim() sk_stream_mem_reclaim() -> sk_mem_reclaim() sk_stream_mem_schedule -> __sk_mem_schedule() sk_stream_pages() -> sk_mem_pages() sk_stream_rmem_schedule() -> sk_rmem_schedule() sk_stream_wmem_schedule() -> sk_wmem_schedule() sk_charge_skb() -> sk_mem_charge() Removeing sk_stream_rfree(): consolidates into sock_rfree() sk_stream_set_owner_r(): consolidates into skb_set_owner_r() sk_stream_mem_schedule() The following functions are added. sk_has_account(): check if the protocol supports accounting sk_mem_uncharge(): do the opposite of sk_mem_charge() In addition, to achieve consolidation, updating sk_wmem_queued is removed from sk_mem_charge(). Next, to consolidate memory accounting functions, this patch adds memory accounting calls to network core functions. Moreover, present memory accounting call is renamed to new accounting call. Finally we replace present memory accounting calls with new interface in TCP and SCTP. Signed-off-by: Takahiro Yasui <tyasui@redhat.com> Signed-off-by: Hideo Aoki <haoki@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28[TCP]: Force TSO splits to MSS boundariesIlpo Järvinen
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[TCP] Avoid two divides in tcp_output.cEric Dumazet
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[TCP]: Fix TSO deferringIlpo Järvinen
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[TCP]: Abstract tp->highest_sack accessing & point to next skbIlpo Järvinen
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[TCP]: Add tcp_for_write_queue_from_safe and use it in mtu_probeIlpo Järvinen
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[TCP]: Remove local variable and use packets_in_flight directlyIlpo Järvinen
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[TCP]: MTUprobe: prepare skb fields earlierIlpo Järvinen
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[NET]: Eliminate unused argument from sk_stream_alloc_pskbPavel Emelyanov
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[TCP]: Move FRTO checks out from write queue abstraction funcsIlpo Järvinen
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[TCP]: Rewrite SACK block processing & sack_recv_cache useIlpo Järvinen
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[TCP]: Convert highest_sack to sk_buff to allow direct accessIlpo Järvinen
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>
2007-12-05[TCP]: NAGLE_PUSH seems to be a wrong way aroundIlpo Järvinen
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 Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-11-23[TCP] MTUprobe: Cleanup send queue check (no need to loop)Ilpo Järvinen
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[TCP]: MTUprobe: receiver window & data available checks fixedIlpo Järvinen
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>
2007-11-19[TCP] MTUprobe: fix potential sk_send_head corruptionIlpo Järvinen
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 Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-11[TCP]: Limit processing lost_retrans loop to work-to-do casesIlpo Järvinen
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>