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path: root/net/ipv4/tcp_input.c
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2009-12-08tcp: fix retrans_stamp advancing in error casesIlpo Järvinen
It can happen, that tcp_retransmit_skb fails due to some error. In such cases we might end up into a state where tp->retrans_out is zero but that's only because we removed the TCPCB_SACKED_RETRANS bit from a segment but couldn't retransmit it because of the error that happened. Therefore some assumptions that retrans_out checks are based do not necessarily hold, as there still can be an old retransmission but that is only visible in TCPCB_EVER_RETRANS bit. As retransmission happen in sequential order (except for some very rare corner cases), it's enough to check the head skb for that bit. Main reason for all this complexity is the fact that connection dying time now depends on the validity of the retrans_stamp, in particular, that successive retransmissions of a segment must not advance retrans_stamp under any conditions. It seems after quick thinking that this has relatively low impact as eventually TCP will go into CA_Loss and either use the existing check for !retrans_stamp case or send a retransmission successfully, setting a new base time for the dying timer (can happen only once). At worst, the dying time will be approximately the double of the intented time. In addition, tcp_packet_delayed() will return wrong result (has some cc aspects but due to rarity of these errors, it's hardly an issue). One of retrans_stamp clearing happens indirectly through first going into CA_Open state and then a later ACK lets the clearing to happen. Thus tcp_try_keep_open has to be modified too. Thanks to Damian Lukowski <damian@tvk.rwth-aachen.de> for hinting that this possibility exists (though the particular case discussed didn't after all have it happening but was just a debug patch artifact). Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-12-02TCPCT part 1g: Responder Cookie => InitiatorWilliam Allen Simpson
Parse incoming TCP_COOKIE option(s). Calculate <SYN,ACK> TCP_COOKIE option. Send optional <SYN,ACK> data. This is a significantly revised implementation of an earlier (year-old) patch that no longer applies cleanly, with permission of the original author (Adam Langley): http://thread.gmane.org/gmane.linux.network/102586 Requires: TCPCT part 1a: add request_values parameter for sending SYNACK TCPCT part 1b: generate Responder Cookie secret TCPCT part 1c: sysctl_tcp_cookie_size, socket option TCP_COOKIE_TRANSACTIONS TCPCT part 1d: define TCP cookie option, extend existing struct's TCPCT part 1e: implement socket option TCP_COOKIE_TRANSACTIONS TCPCT part 1f: Initiator Cookie => Responder Signed-off-by: William.Allen.Simpson@gmail.com Signed-off-by: David S. Miller <davem@davemloft.net>
2009-11-23net/ipv4: Move && and || to end of previous lineJoe Perches
On Sun, 2009-11-22 at 16:31 -0800, David Miller wrote: > It should be of the form: > if (x && > y) > > or: > if (x && y) > > Fix patches, rather than complaints, for existing cases where things > do not follow this pattern are certainly welcome. Also collapsed some multiple tabs to single space. Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-11-13net: TCP_MSS_DEFAULT, TCP_MSS_DESIREDWilliam Allen Simpson
Define two symbols needed in both kernel and user space. Remove old (somewhat incorrect) kernel variant that wasn't used in most cases. Default should apply to both RMSS and SMSS (RFC2581). Replace numeric constants with defined symbols. Stand-alone patch, originally developed for TCPCT. Signed-off-by: William.Allen.Simpson@gmail.com Acked-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-11-04tcp: Use defaults when no route options are availableGilad Ben-Yossef
Trying to parse the option of a SYN packet that we have no route entry for should just use global wide defaults for route entry options. Signed-off-by: Gilad Ben-Yossef <gilad@codefidence.com> Tested-by: Valdis.Kletnieks@vt.edu Signed-off-by: David S. Miller <davem@davemloft.net>
2009-10-29Allow disabling of DSACK TCP option per routeGilad Ben-Yossef
Add and use no DSCAK bit in the features field. Signed-off-by: Gilad Ben-Yossef <gilad@codefidence.com> Sigend-off-by: Ori Finkelman <ori@comsleep.com> Sigend-off-by: Yony Amit <yony@comsleep.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-10-29Allow to turn off TCP window scale opt per routeGilad Ben-Yossef
Add and use no window scale bit in the features field. Note that this is not the same as setting a window scale of 0 as would happen with window limit on route. Signed-off-by: Gilad Ben-Yossef <gilad@codefidence.com> Sigend-off-by: Ori Finkelman <ori@comsleep.com> Sigend-off-by: Yony Amit <yony@comsleep.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-10-29Allow disabling TCP timestamp options per routeGilad Ben-Yossef
Implement querying and acting upon the no timestamp bit in the feature field. Signed-off-by: Gilad Ben-Yossef <gilad@codefidence.com> Sigend-off-by: Ori Finkelman <ori@comsleep.com> Sigend-off-by: Yony Amit <yony@comsleep.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-10-29Add the no SACK route option featureGilad Ben-Yossef
Implement querying and acting upon the no sack bit in the features field. Signed-off-by: Gilad Ben-Yossef <gilad@codefidence.com> Sigend-off-by: Ori Finkelman <ori@comsleep.com> Sigend-off-by: Yony Amit <yony@comsleep.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-10-29Allow tcp_parse_options to consult dst entryGilad Ben-Yossef
We need tcp_parse_options to be aware of dst_entry to take into account per dst_entry TCP options settings Signed-off-by: Gilad Ben-Yossef <gilad@codefidence.com> Sigend-off-by: Ori Finkelman <ori@comsleep.com> Sigend-off-by: Yony Amit <yony@comsleep.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-10-28net: Corrected spelling error heurestics->heuristicsAndreas Petlund
Corrected a spelling error in a function name. Signed-off-by: Andreas Petlund <apetlund@simula.no> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-09-15tcp: fix ssthresh u16 leftoverIlpo Järvinen
It was once upon time so that snd_sthresh was a 16-bit quantity. ...That has not been true for long period of time. I run across some ancient compares which still seem to trust such legacy. Put all that magic into a single place, I hopefully found all of them. Compile tested, though linking of allyesconfig is ridiculous nowadays it seems. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-09-01Revert Backoff [v3]: Revert RTO on ICMP destination unreachableDamian Lukowski
Here, an ICMP host/network unreachable message, whose payload fits to TCP's SND.UNA, is taken as an indication that the RTO retransmission has not been lost due to congestion, but because of a route failure somewhere along the path. With true congestion, a router won't trigger such a message and the patched TCP will operate as standard TCP. This patch reverts one RTO backoff, if an ICMP host/network unreachable message, whose payload fits to TCP's SND.UNA, arrives. Based on the new RTO, the retransmission timer is reset to reflect the remaining time, or - if the revert clocked out the timer - a retransmission is sent out immediately. Backoffs are only reverted, if TCP is in RTO loss recovery, i.e. if there have been retransmissions and reversible backoffs, already. Changes from v2: 1) Renaming of skb in tcp_v4_err() moved to another patch. 2) Reintroduced tcp_bound_rto() and __tcp_set_rto(). 3) Fixed code comments. Signed-off-by: Damian Lukowski <damian@tvk.rwth-aachen.de> Acked-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-05-29tcp: fix loop in ofo handling code and reduce its complexityIlpo Järvinen
Somewhat luckily, I was looking into these parts with very fine comb because I've made somewhat similar changes on the same area (conflicts that arose weren't that lucky though). The loop was very much overengineered recently in commit 915219441d566 (tcp: Use SKB queue and list helpers instead of doing it by-hand), while it basically just wants to know if there are skbs after 'skb'. Also it got broken because skb1 = skb->next got translated into skb1 = skb1->next (though abstracted) improperly. Note that 'skb1' is pointing to previous sk_buff than skb or NULL if at head. Two things went wrong: - We'll kfree 'skb' on the first iteration instead of the skbuff following 'skb' (it would require required SACK reneging to recover I think). - The list head case where 'skb1' is NULL is checked too early and the loop won't execute whereas it previously did. Conclusion, mostly revert the recent changes which makes the cset very messy looking but using proper accessor in the previous-like version. The effective changes against the original can be viewed with: git-diff 915219441d566f1da0caa0e262be49b666159e17^ \ net/ipv4/tcp_input.c | sed -n -e '57,70 p' Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-05-28tcp: Use SKB queue and list helpers instead of doing it by-hand.David S. Miller
Signed-off-by: David S. Miller <davem@davemloft.net>
2009-05-08Merge branch 'master' of ↵David S. Miller
master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 Conflicts: include/net/tcp.h
2009-05-04tcp: Fix tcp_prequeue() to get correct rto_min valueSatoru SATOH
tcp_prequeue() refers to the constant value (TCP_RTO_MIN) regardless of the actual value might be tuned. The following patches fix this and make tcp_prequeue get the actual value returns from tcp_rto_min(). Signed-off-by: Satoru SATOH <satoru.satoh@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-05-04tcp: extend ECN sysctl to allow server-side only ECNIlpo Järvinen
This should be very safe compared with full enabled, so I see no reason why it shouldn't be done right away. As ECN can only be negotiated if the SYN sending party is also supporting it, somebody in the loop probably knows what he/she is doing. If SYN does not ask for ECN, the server side SYN-ACK is identical to what it is without ECN. Thus it's quite safe. The chosen value is safe w.r.t to existing configs which choose to currently set manually either 0 or 1 but silently upgrades those who have not explicitly requested ECN off. Whether to just enable both sides comes up time to time but unless that gets done now we can at least make the servers aware of ECN already. As there are some known problems to occur if ECN is enabled, it's currently questionable whether there's any real gain from enabling clients as servers mostly won't support it anyway (so we'd hit just the negative sides). After enabling the servers and getting that deployed, the client end enable really has some potential gain too. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-04-14tcp: fix >2 iw selectionIlpo Järvinen
A long-standing feature in tcp_init_metrics() is such that any of its goto reset prevents call to tcp_init_cwnd(). Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-03-22tcp: Discard segments that ack data not yet sentJohn Dykstra
Discard incoming packets whose ack field iincludes data not yet sent. This is consistent with RFC 793 Section 3.9. Change tcp_ack() to distinguish between too-small and too-large ack field values. Keep segments with too-large ack fields out of the fast path, and change slow path to discard them. Reported-by: Oliver Zheng <mailinglists+netdev@oliverzheng.com> Signed-off-by: John Dykstra <john.dykstra1@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-03-21net/*: use linux/kernel.h swap()Ilpo Järvinen
tcp_sack_swap seems unnecessary so I pushed swap to the caller. Also removed comment that seemed then pointless, and added include when not already there. Compile tested. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-03-15tcp: simplify tcp_current_mssIlpo Järvinen
There's very little need for most of the callsites to get tp->xmit_goal_size updated. That will cost us divide as is, so slice the function in two. Also, the only users of the tp->xmit_goal_size are directly behind tcp_current_mss(), so there's no need to store that variable into tcp_sock at all! The drop of xmit_goal_size currently leaves 16-bit hole and some reorganization would again be necessary to change that (but I'm aiming to fill that hole with u16 xmit_goal_size_segs to cache the results of the remaining divide to get that tso on regression). Bring xmit_goal_size parts into tcp.c Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Cc: Evgeniy Polyakov <zbr@ioremap.net> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-03-15tcp: don't check mtu probe completion in the loopIlpo Järvinen
It seems that no variables clash such that we couldn't do the check just once later on. Therefore move it. Also kill dead obvious comment, dead argument and add unlikely since this mtu probe does not happen too often. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-03-15tcp: consolidate paws checkIlpo Järvinen
Wow, it was quite tricky to merge that stream of negations but I think I finally got it right: check & replace_ts_recent: (s32)(rcv_tsval - ts_recent) >= 0 => 0 (s32)(ts_recent - rcv_tsval) <= 0 => 0 discard: (s32)(ts_recent - rcv_tsval) > TCP_PAWS_WINDOW => 1 (s32)(ts_recent - rcv_tsval) <= TCP_PAWS_WINDOW => 0 I toggled the return values of tcp_paws_check around since the old encoding added yet-another negation making tracking of truth-values really complicated. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-03-15tcp: kill dead end_seq variable in clean_rtx_queueIlpo Järvinen
I've already forgotten what for this was necessary, anyway it's no longer used (if it ever was). Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-03-15tcp: remove pointless .dsack/.num_sacks codeIlpo Järvinen
In the pure assignment case, the earlier zeroing is still in effect. David S. Miller raised concerns if the ifs are there to avoid dirtying cachelines. I came to these conclusions: > We'll be dirty it anyway (now that I check), the first "real" statement > in tcp_rcv_established is: > > tp->rx_opt.saw_tstamp = 0; > > ...that'll land on the same dword. :-/ > > I suppose the blocks are there just because they had more complexity > inside when they had to calculate the eff_sacks too (maybe it would > have been better to just remove them in that drop-patch so you would > have had less head-ache :-)). Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-03-02tcp: tcp_init_wl / tcp_update_wl argument cleanupHantzis Fotis
The above functions from include/net/tcp.h have been defined with an argument that they never use. The argument is 'u32 ack' which is never used inside the function body, and thus it can be removed. The rest of the patch involves the necessary changes to the function callers of the above two functions. Signed-off-by: Hantzis Fotis <xantzis@ceid.upatras.gr> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-03-02tcp: kill eff_sacks "cache", the sole user can calculate itselfIlpo Järvinen
Also fixes insignificant bug that would cause sending of stale SACK block (would occur in some corner cases). Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-03-02tcp: separate timeout marking loop to it's own functionIlpo Järvinen
Some comment about its current state added. So far I have seen very few cases where the thing is actually useful, usually just marginally (though admittedly I don't usually see top of window losses where it seems possible that there could be some gain), instead, more often the cases suffer from L-marking spike which is certainly not desirable (I'll bury improving it to my todo list, but on a low prio position). Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-03-02tcp: remove redundant code from tcp_mark_lost_retransIlpo Järvinen
Arnd Hannemann <hannemann@nets.rwth-aachen.de> noticed and was puzzled by the fact that !tcp_is_fack(tp) leads to early return near the beginning and the later on tcp_is_fack(tp) was still used in an if condition. The later check was a left-over from RFC3517 SACK stuff (== !tcp_is_fack(tp) behavior nowadays) as there wasn't clear way how to handle this particular check cheaply in the spirit of RFC3517 (using only SACK blocks, not holes + SACK blocks as with FACK). I sort of left it there as a reminder but since it's confusing other people just remove it and comment the missing-feature stuff instead. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Cc: Arnd Hannemann <hannemann@nets.rwth-aachen.de> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-03-02tcp: fix lost_cnt_hint miscountsIlpo Järvinen
It is possible that lost_cnt_hint gets underflow in tcp_clean_rtx_queue because the cumulative ACK can cover the segment where lost_skb_hint points to only partially, which means that the hint is not cleared, opposite to what my (earlier) comment claimed. Also I don't agree what I ended up writing about non-trivial case there to be what I intented to say. It was not supposed to happen that the hint won't get cleared and we underflow in any scenario. In general, this is quite hard to trigger in practice. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-03-01tcp: fix retrans_out leaksIlpo Järvinen
There's conflicting assumptions in shifting, the caller assumes that dupsack results in S'ed skbs (or a part of it) for sure but never gave a hint to tcp_sacktag_one when dsack is actually in use. Thus DSACK retrans_out -= pcount was not taken and the counter became out of sync. Remove obstacle from that information flow to get DSACKs accounted in tcp_sacktag_one as expected. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Tested-by: Denys Fedoryshchenko <denys@visp.net.lb> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-01-06net_dma: convert to dma_find_channelDan Williams
Use the general-purpose channel allocation provided by dmaengine. Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2008-12-05tcp: share code through function, not through copy-paste. :-)Ilpo Järvinen
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-12-05tcp: drop tcp_bound_rto, merge content of it tcp_set_rtoIlpo Järvinen
Both are called by the same sites. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-12-05tcp: no need to pass prev skb around, reduces arg pressureIlpo Järvinen
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-12-05tcp: introduce struct tcp_sacktag_state to reduce arg pressureIlpo Järvinen
There are just too many args to some sacktag functions. This idea was first proposed by David S. Miller around a year ago, and the current situation is much worse that what it was back then. tcp_sacktag_one can be made a bit simpler by returning the new sacked (it can be achieved with a single variable though the previous code "caching" sacked into a local variable and therefore it is not exactly equal but the results will be the same). codiff on x86_64 tcp_sacktag_one | -15 tcp_shifted_skb | -50 tcp_match_skb_to_sack | -1 tcp_sacktag_walk | -64 tcp_sacktag_write_queue | -59 tcp_urg | +1 tcp_event_data_recv | -1 7 functions changed, 1 bytes added, 190 bytes removed, diff: -189 Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-12-05tcp: make mtu probe failure to not break gso'ed skbs unnecessarilyIlpo Järvinen
I noticed that since skb->len has nothing to do with actual segment length with gso, we need to figure it out separately, reuse a function from the recent shifting stuff (generalize it). Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-12-05tcp: Fix thinko making the not-shiftable to cover S|R as wellIlpo Järvinen
S|R won't result in S if just SACK is received. DSACK is another story (but it is covered correctly already). Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-12-05tcp: force mss equality with the next skb too.Ilpo Järvinen
Also make if-goto forest nicer looking. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-11-25tcp: tcp_limit_reno_sacked can become staticIlpo Järvinen
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-11-24tcp: add some mibs to track collapsingIlpo Järvinen
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-11-24tcp: Make shifting not clear the hintsIlpo Järvinen
The earlier version was just very basic one which is "playing safe" by always clearing the hints. However, clearing of a hint is extremely costly operation with large windows, so it must be avoided at all cost whenever possible, there is a way with shifting too achieve not-clearing. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-11-24tcp: Try to restore large SKBs while SACK processingIlpo Järvinen
During SACK processing, most of the benefits of TSO are eaten by the SACK blocks that one-by-one fragment SKBs to MSS sized chunks. Then we're in problems when cleanup work for them has to be done when a large cumulative ACK comes. Try to return back to pre-split state already while more and more SACK info gets discovered by combining newly discovered SACK areas with the previous skb if that's SACKed as well. This approach has a number of benefits: 1) The processing overhead is spread more equally over the RTT 2) Write queue has less skbs to process (affect everything which has to walk in the queue past the sacked areas) 3) Write queue is consistent whole the time, so no other parts of TCP has to be aware of this (this was not the case with some other approach that was, well, quite intrusive all around). 4) Clean_rtx_queue can release most of the pages using single put_page instead of previous PAGE_SIZE/mss+1 calls In case a hole is fully filled by the new SACK block, we attempt to combine the next skb too which allows construction of skbs that are even larger than what tso split them to and it handles hole per on every nth patterns that often occur during slow start overshoot pretty nicely. Though this to be really useful also a retransmission would have to get lost since cumulative ACKs advance one hole at a time in the most typical case. TODO: handle upwards only merging. That should be rather easy when segment is fully sacked but I'm leaving that as future work item (it won't make very large difference anyway since this current approach already covers quite a lot of normal cases). I was earlier thinking of some sophisticated way of tracking timestamps of the first and the last segment but later on realized that it won't be that necessary at all to store the timestamp of the last segment. The cases that can occur are basically either: 1) ambiguous => no sensible measurement can be taken anyway 2) non-ambiguous is due to reordering => having the timestamp of the last segment there is just skewing things more off than does some good since the ack got triggered by one of the holes (besides some substle issues that would make determining right hole/skb even harder problem). Anyway, it has nothing to do with this change then. I choose to route some abnormal looking cases with goto noop, some could be handled differently (eg., by stopping the walking at that skb but again). In general, they either shouldn't happen at all or are rare enough to make no difference in practice. In theory this change (as whole) could cause some macroscale regression (global) because of cache misses that are taken over the round-trip time but it gets very likely better because of much less (local) cache misses per other write queue walkers and the big recovery clearing cumulative ack. Worth to note that these benefits would be very easy to get also without TSO/GSO being on as long as the data is in pages so that we can merge them. Currently I won't let that happen because DSACK splitting at fragment that would mess up pcounts due to sk_can_gso in tcp_set_skb_tso_segs. Once DSACKs fragments gets avoided, we have some conditions that can be made less strict. TODO: I will probably have to convert the excessive pointer passing to struct sacktag_state... :-) My testing revealed that considerable amount of skbs couldn't be shifted because they were cloned (most likely still awaiting tx reclaim)... [The rest is considering future work instead since I got repeatably EFAULT to tcpdump's recvfrom when I added pskb_expand_head to deal with clones, so I separated that into another, later patch] ...To counter that, I gave up on the fifth advantage: 5) When growing previous SACK block, less allocs for new skbs are done, basically a new alloc is needed only when new hole is detected and when the previous skb runs out of frags space ...which now only happens of if reclaim is fast enough to dispose the clone before the SACK block comes in (the window is RTT long), otherwise we'll have to alloc some. With clones being handled I got these numbers (will be somewhat worse without that), taken with fine-grained mibs: TCPSackShifted 398 TCPSackMerged 877 TCPSackShiftFallback 320 TCPSACKCOLLAPSEFALLBACKGSO 0 TCPSACKCOLLAPSEFALLBACKSKBBITS 0 TCPSACKCOLLAPSEFALLBACKSKBDATA 0 TCPSACKCOLLAPSEFALLBACKBELOW 0 TCPSACKCOLLAPSEFALLBACKFIRST 1 TCPSACKCOLLAPSEFALLBACKPREVBITS 318 TCPSACKCOLLAPSEFALLBACKMSS 1 TCPSACKCOLLAPSEFALLBACKNOHEAD 0 TCPSACKCOLLAPSEFALLBACKSHIFT 0 TCPSACKCOLLAPSENOOPSEQ 0 TCPSACKCOLLAPSENOOPSMALLPCOUNT 0 TCPSACKCOLLAPSENOOPSMALLLEN 0 TCPSACKCOLLAPSEHOLE 12 Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-11-24tcp: make tcp_sacktag_one able to handle partial skb tooIlpo Järvinen
This is preparatory work for SACK combiner patch which may have to count TCP state changes for only a part of the skb because it will intentionally avoids splitting skb to SACKed and not sacked parts. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-11-24tcp: Make SACK code to split only at mss boundariesIlpo Järvinen
Sadly enough, this adds possible divide though we try to avoid it by checking one mss as common case. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-11-24tcp: more aggressive skippingIlpo Järvinen
I knew already when rewriting the sacktag that this condition was too conservative, change it now since it prevent lot of useless work (especially in the sack shifter decision code that is being added by a later patch). This shouldn't change anything really, just save some processing regardless of the shifter. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-11-24tcp: move tcp_simple_retransmit to tcp_inputIlpo Järvinen
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-10-31net: replace NIPQUAD() in net/ipv4/ net/ipv6/Harvey Harrison
Using NIPQUAD() with NIPQUAD_FMT, %d.%d.%d.%d or %u.%u.%u.%u can be replaced with %pI4 Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-10-29net: replace %p6 with %pI6Harvey Harrison
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>