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path: root/net/ipv4/tcp_output.c
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2007-10-11[TCP]: Limit processing lost_retrans loop to work-to-do casesIlpo Järvinen1-0/+2
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>
2007-10-10[TCP]: Fix two off-by-one errors in fackets_out adjusting logicIlpo Järvinen1-2/+4
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[TCP]: No fackets_out/highest_sack tuning when SACK isn't enabledIlpo Järvinen1-3/+4
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[TCP]: Re-place highest_sack check to a more robust positionIlpo Järvinen1-4/+4
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[TCP]: Avoid clearing sacktag hint in trivial situationsIlpo Järvinen1-4/+8
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[TCP]: clear_all_retrans_hints prefixed by tcp_Ilpo Järvinen1-3/+3
In addition, fix its function comment spacing. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
2007-10-10[TCP]: Make fackets_out accurateIlpo Järvinen1-18/+26
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[TCP]: Maintain highest_sack accurately to the highest skbIlpo Järvinen1-0/+7
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[NET] Cleanup: DIV_ROUND_UPIlpo Järvinen1-5/+1
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10[TCP]: tcp_packets_out_inc to tcp_output.c (no callers elsewhere)Ilpo Järvinen1-0/+12
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10[TCP]: Remove unnecessary wrapper tcp_packets_out_decIlpo Järvinen1-1/+1
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[TCP]: Move sack_ok access to obviously named funcs & cleanupIlpo Järvinen1-3/+3
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[TCP]: Left out sync->verify (the new meaning of it) & definifyIlpo Järvinen1-2/+2
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[TCP]: Tighten tcp_sock's belt, drop left_outIlpo Järvinen1-9/+3
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[TCP]: Add tcp_dec_pcount_approx int variantIlpo Järvinen1-9/+3
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10[TCP]: Move code from tcp_ecn.h to tcp*.c and tcp.h & remove itIlpo Järvinen1-0/+50
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[TCP]: Access to highest_sack obsoletes forward_cnt_hintIlpo Järvinen1-14/+9
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>
2007-07-19[NET] IPV4: Fix whitespace errors.YOSHIFUJI Hideaki1-1/+1
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
2007-07-10[TCP]: SACK fastpath did override adjusted fackets_outIlpo Järvinen1-0/+8
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>
2007-05-08header cleaning: don't include smp_lock.h when not usedRandy Dunlap1-1/+0
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>
2007-04-30[TCP] FRTO: RFC4138 allows Nagle override when new data must be sentIlpo Järvinen1-2/+4
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>
2007-04-28[TCP]: Update references in two old commentsGerrit Renker1-1/+1
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>
2007-04-25[TCP]: Congestion control API update.Stephen Hemminger1-1/+1
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[TCP]: Sed magic converts func(sk, tp, ...) -> func(sk, ...)Ilpo Järvinen1-25/+29
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[SK_BUFF]: Some more conversions to skb_copy_from_linear_dataArnaldo Carvalho de Melo1-1/+3
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
2007-04-25[SK_BUFF]: Convert skb->tail to sk_buff_data_tArnaldo Carvalho de Melo1-1/+1
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[SK_BUFF]: Introduce tcp_hdr(), remove skb->h.thArnaldo Carvalho de Melo1-5/+8
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-04-25[TCP]: whitespace cleanupStephen Hemminger1-16/+18
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[TCP]: Abstract out all write queue operations.David S. Miller1-51/+44
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[TCP]: Add two new spurious RTO responses to FRTOIlpo Järvinen1-1/+1
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>
2007-04-09[TCP]: slow_start_after_idle should influence cwnd validation tooDavid S. Miller1-1/+2
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>
2007-04-02[TCP]: Do receiver-side SWS avoidance for rcvbuf < MSS.John Heffner1-0/+3
Signed-off-by: John Heffner <jheffner@psc.edu> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-02-13[TCP]: Prevent pseudo garbage in SYN's advertized windowIlpo Järvinen1-2/+2
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>
2007-02-10[NET] IPV4: Fix whitespace errors.YOSHIFUJI Hideaki1-31/+31
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-02-08[TCP]: Don't apply FIN exception to full TSO segments.John Heffner1-1/+2
Signed-off-by: John Heffner <jheffner@psc.edu> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-01-26[TCP]: Restore SKB socket owner setting in tcp_transmit_skb().David S. Miller1-1/+2
Revert 931731123a103cfb3f70ac4b7abfc71d94ba1f03 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>
2007-01-23[TCP]: rare bad TCP checksum with 2.6.19Jarek Poplawski1-1/+2
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>
2006-12-02[TCP]: MD5 Signature Option (RFC2385) support.YOSHIFUJI Hideaki1-5/+106
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[TCP/DCCP]: Introduce net_xmit_evalGerrit Renker1-7/+1
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[TCP]: Don't set SKB owner in tcp_transmit_skb().David S. Miller1-2/+1
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>
2006-10-18[TCP]: Bound TSO defer timeJohn Heffner1-5/+15
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>
2006-10-11[NET]: Use hton{l,s}() for non-initializers.YOSHIFUJI Hideaki1-11/+20
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2006-09-28[TCP] net/ipv4/tcp_output.c: trivial annotationsAl Viro1-6/+6
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: David S. Miller <davem@davemloft.net>
2006-09-22[NET/IPV4/IPV6]: Change some sysctl variables to __read_mostlyBrian Haley1-6/+6
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[NET]: Replace CHECKSUM_HW by CHECKSUM_PARTIAL/CHECKSUM_COMPLETEPatrick McHardy1-10/+8
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>
2006-08-22[TCP]: Limit window scaling if window is clamped.Stephen Hemminger1-0/+1
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>
2006-08-07[TCP]: SNMPv2 tcpOutSegs counter errorWei Yongjun1-3/+9
Do not count retransmitted segments. Signed-off-by: Wei Yongjun <yjwei@nanjing-fnst.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2006-06-30[NET]: Generalise TSO-specific bits from skb_setup_capsHerbert Xu1-6/+3
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>
2006-06-29[NET]: Add ECN support for TSOMichael Chan1-2/+0
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>
2006-06-23[NET]: Merge TSO/UFO fields in sk_buffHerbert Xu1-19/+28
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>