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2008-11-06Merge branch 'master' of ↵David S. Miller
master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 Conflicts: drivers/net/wireless/ath5k/base.c net/8021q/vlan_core.c
2008-11-01net: add documentation for skb recyclingStephen Hemminger
Commit 04a4bb55bcf35b63d40fd2725e58599ff8310dd7 ("net: add skb_recycle_check() to enable netdriver skb recycling") added a method for network drivers to recycle skbuffs, but while use of this mechanism was documented in the commit message, it should really have been added as a docbook comment as well -- this patch does that. Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> Signed-off-by: Lennert Buytenhek <buytenh@marvell.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-10-31mac80211: Re-enable aggregationSujith
Wireless HW without any dedicated queues for aggregation do not need the ampdu_queues mechanism present right now in mac80211. Since mac80211 is still incomplete wrt TX MQ changes, do not allow aggregation sessions for drivers that set ampdu_queues. This is only an interim hack until Intel fixes the requeue issue. Signed-off-by: Sujith <Sujith.Manoharan@atheros.com> Signed-off-by: Luis Rodriguez <Luis.Rodriguez@Atheros.com> Signed-off-by: John W. Linville <linville@tuxdriver.com>
2008-10-28net: reduce structures when XFRM=nAlexey Dobriyan
ifdef out * struct sk_buff::sp (pointer) * struct dst_entry::xfrm (pointer) * struct sock::sk_policy (2 pointers) Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-10-13net: Rationalise email address: Network Specific PartsAlan Cox
Clean up the various different email addresses of mine listed in the code to a single current and valid address. As Dave says his network merges for 2.6.28 are now done this seems a good point to send them in where they won't risk disrupting real changes. Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-10-07net: packet split receive apiPeter Zijlstra
Add some packet-split receive hooks. For one this allows to do NUMA node affine page allocs. Later on these hooks will be extended to do emergency reserve allocations for fragments. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-10-01net: BUG instead of corrupting memory in pskb_expand_headHerbert Xu
If the caller of pskb_expand_head specifies a negative nhead we'll silently overwrite other people's memory. This patch makes it BUG instead. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-10-01net: add skb_recycle_check() to enable netdriver skb recyclingLennert Buytenhek
This patch adds skb_recycle_check(), which can be used by a network driver after transmitting an skb to check whether this skb can be recycled as a receive buffer. skb_recycle_check() checks that the skb is not shared or cloned, and that it is linear and its head portion large enough (as determined by the driver) to be recycled as a receive buffer. If these conditions are met, it does any necessary reference count dropping and cleans up the skbuff as if it just came from __alloc_skb(). Signed-off-by: Lennert Buytenhek <buytenh@marvell.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-08-15net: Preserve netfilter attributes in skb_gso_segment using __copy_skb_headerHerbert Xu
skb_gso_segment didn't preserve some attributes in the original skb such as the netfilter fields. This was harmless until they were used which is the case for packets going through lo. This patch makes it call __copy_skb_header which also picks up some other missing attributes. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-29mac80211: partially fix skb->cb useJohannes Berg
This patch fixes mac80211 to not use the skb->cb over the queue step from virtual interfaces to the master. The patch also, for now, disables aggregation because that would still require requeuing, will fix that in a separate patch. There are two other places (software requeue and powersaving stations) where requeue can happen, but that is not currently used by any drivers/not possible to use respectively. Signed-off-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: John W. Linville <linville@tuxdriver.com>
2008-07-25net: convert BUG_TRAP to generic WARN_ONIlpo Järvinen
Removes legacy reinvent-the-wheel type thing. The generic machinery integrates much better to automated debugging aids such as kerneloops.org (and others), and is unambiguous due to better naming. Non-intuively BUG_TRAP() is actually equal to WARN_ON() rather than BUG_ON() though some might actually be promoted to BUG_ON() but I left that to future. I could make at least one BUILD_BUG_ON conversion. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-16net: make __skb_splice_bits staticHarvey Harrison
net/core/skbuff.c:1335:5: warning: symbol '__skb_splice_bits' was not declared. Should it be static? Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-15net: refactor tcp splice receive path to improve readabilityOctavian Purdila
- move all of the details on offsets, lengths and buffers into a single function instead of doing these operation from multiple places - use a bottom up approach: try to avoid details in the high level functions, introduce them gradually as we go deeper in the function call stack With helpful feedback from Jarek Poplawski. Signed-off-by: Octavian Purdila <opurdila@ixiacom.com> Acked-by: Jarek Poplawski <jarkao2@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-14vlan: Don't store VLAN tag in cbPatrick McHardy
Use a real skb member to store the skb to avoid clashes with qdiscs, which are allowed to use the cb area themselves. As currently only real devices that consume the skb set the NETIF_F_HW_VLAN_TX flag, no explicit invalidation is neccessary. The new member fills a hole on 64 bit, the skb layout changes from: __u32 mark; /* 172 4 */ sk_buff_data_t transport_header; /* 176 4 */ sk_buff_data_t network_header; /* 180 4 */ sk_buff_data_t mac_header; /* 184 4 */ sk_buff_data_t tail; /* 188 4 */ /* --- cacheline 3 boundary (192 bytes) --- */ sk_buff_data_t end; /* 192 4 */ /* XXX 4 bytes hole, try to pack */ to __u32 mark; /* 172 4 */ __u16 vlan_tci; /* 176 2 */ /* XXX 2 bytes hole, try to pack */ sk_buff_data_t transport_header; /* 180 4 */ sk_buff_data_t network_header; /* 184 4 */ Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-06-28Merge branch 'master' of ↵David S. Miller
master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 Conflicts: drivers/net/wireless/iwlwifi/iwl4965-base.c
2008-06-27tcp: fix for splice receive when used with software LROOctavian Purdila
If an skb has nr_frags set to zero but its frag_list is not empty (as it can happen if software LRO is enabled), and a previous tcp_read_sock has consumed the linear part of the skb, then __skb_splice_bits: (a) incorrectly reports an error and (b) forgets to update the offset to account for the linear part Any of the two problems will cause the subsequent __skb_splice_bits call (the one that handles the frag_list skbs) to either skip data, or, if the unadjusted offset is greater then the size of the next skb in the frag_list, make tcp_splice_read loop forever. Signed-off-by: Octavian Purdila <opurdila@ixiacom.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-06-19net: Discard and warn about LRO'd skbs received for forwardingBen Hutchings
Add skb_warn_if_lro() to test whether an skb was received with LRO and warn if so. Change br_forward(), ip_forward() and ip6_forward() to call it) and discard the skb if it returns true. Signed-off-by: Ben Hutchings <bhutchings@solarflare.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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>
2008-06-04tcp: Fix for race due to temporary drop of the socket lock in skb_splice_bits.Octavian Purdila
skb_splice_bits temporary drops the socket lock while iterating over the socket queue in order to break a reverse locking condition which happens with sendfile. This, however, opens a window of opportunity for tcp_collapse() to aggregate skbs and thus potentially free the current skb used in skb_splice_bits and tcp_read_sock. This patch fixes the problem by (re-)getting the same "logical skb" after the lock has been temporary dropped. Based on idea and initial patch from Evgeniy Polyakov. Signed-off-by: Octavian Purdila <opurdila@ixiacom.com> Acked-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-05-03net: Fix useless comment reference loop.Johannes Berg
include/linux/skbuff.h says: /* These elements must be at the end, see alloc_skb() for details. */ net/core/skbuff.c says: * See comment in sk_buff definition, just before the 'tail' member This patch contains my guess as to the actual reason rather than a dead comment reference loop. Signed-off-by: Johannes Berg <johannes@sipsolutions.net> 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
2008-04-14[SKB]: __skb_append = __skb_queue_after Gerrit Renker
This expresses __skb_append in terms of __skb_queue_after, exploiting that __skb_append(old, new, list) = __skb_queue_after(list, old, new). Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-04-13[NET]: Fix kernel-doc for skb_segmentBen Hutchings
The kernel-doc comment for skb_segment is clearly wrong. This states what it actually does. Signed-off-by: Ben Hutchings <bhutchings@solarflare.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-03-28[NET]: Fix dev_alloc_skb() typo.David S. Miller
Noticed by Joe Perches. Signed-off-by: David S. Miller <davem@davemloft.net>
2008-03-28[NET]: Add inline intent commentary to dev_alloc_skb().Denys Vlasenko
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-03-27[NET]: uninline skb_trim, de-bloatsIlpo Järvinen
Allyesconfig (v2.6.24-mm1): -10976 209 funcs, 123 +, 11099 -, diff: -10976 --- skb_trim Without number of debug related CONFIGs (v2.6.25-rc2-mm1): -7360 192 funcs, 131 +, 7491 -, diff: -7360 --- skb_trim skb_trim | +42 Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-03-27[NET]: uninline skb_push, de-bloats a lotIlpo Järvinen
Allyesconfig (v2.6.24-mm1): -21593 356 funcs, 2418 +, 24011 -, diff: -21593 --- skb_push Without many debug related CONFIGs (v2.6.25-rc2-mm1): -13890 341 funcs, 189 +, 14079 -, diff: -13890 --- skb_push skb_push | +46 Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-03-27[NET]: uninline dev_alloc_skb, de-bloats a lotIlpo Järvinen
Allyesconfig (v2.6.24-mm1): -23668 392 funcs, 104 +, 23772 -, diff: -23668 --- dev_alloc_skb Without many debug CONFIGs (v2.6.25-rc2-mm1): -12178 382 funcs, 157 +, 12335 -, diff: -12178 --- dev_alloc_skb dev_alloc_skb | +37 Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-03-27[NET]: uninline skb_pull, de-bloats a lotIlpo Järvinen
Allyesconfig (v2.6.24-mm1): -28162 354 funcs, 3005 +, 31167 -, diff: -28162 --- skb_pull Without number of debug related CONFIGs (v2.6.25-rc2-mm1): -9697 338 funcs, 221 +, 9918 -, diff: -9697 --- skb_pull skb_pull | +44 Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-03-27[NET]: uninline skb_put, de-bloats a lotIlpo Järvinen
Allyesconfig (v2.6.24-mm1): ~500 files changed ... 869 funcs, 198 +, 111003 -, diff: -110805 --- skb_put skb_put | +104 Without number of debug related CONFIGs (v2.6.25-rc2-mm1): -60744 855 funcs, 861 +, 61605 -, diff: -60744 --- skb_put skb_put | +57 Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-02-15Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6Linus Torvalds
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (82 commits) [NET]: Make sure sockets implement splice_read netconsole: avoid null pointer dereference at show_local_mac() [IPV6]: Fix reversed local_df test in ip6_fragment [XFRM]: Avoid bogus BUG() when throwing new policy away. [AF_KEY]: Fix bug in spdadd [NETFILTER] nf_conntrack_proto_tcp.c: Mistyped state corrected. net: xfrm statistics depend on INET [NETFILTER]: make secmark_tg_destroy() static [INET]: Unexport inet_listen_wlock [INET]: Unexport __inet_hash_connect [NET]: Improve cache line coherency of ingress qdisc [NET]: Fix race in dev_close(). (Bug 9750) [IPSEC]: Fix bogus usage of u64 on input sequence number [RTNETLINK]: Send a single notification on device state changes. [NETLABLE]: Hide netlbl_unlabel_audit_addr6 under ifdef CONFIG_IPV6. [NETLABEL]: Don't produce unused variables when IPv6 is off. [NETLABEL]: Compilation for CONFIG_AUDIT=n case. [GENETLINK]: Relax dances with genl_lock. [NETLABEL]: Fix lookup logic of netlbl_domhsh_search_def. [IPV6]: remove unused method declaration (net/ndisc.h). ...
2008-02-13docbook: make a networking book and fix a few errorsRandy Dunlap
Move networking (core and drivers) docbook to its own networking book. Fix a few kernel-doc errors in header and source files. Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: Neil Brown <neilb@suse.de> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-12[NET]: Fix comment for skb_pull_rcsumUrs Thuermann
Fix comment for skb_pull_rcsum Signed-off-by: Urs Thuermann <urs@isnogud.escape.de> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-02-04virtio: Implement skb_partial_csum_set, for setting partial csums on ↵Rusty Russell
untrusted packets. Use it in virtio_net (replacing buggy version there), it's also going to be used by TAP for partial csum support. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Acked-by: David S. Miller <davem@davemloft.net>
2008-01-28[TCP]: Splice receive support.Jens Axboe
Support for network splice receive. Signed-off-by: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-08[NET]: Clone the sk_buff 'iif' field in __skb_clone()Paul Moore
Both NetLabel and SELinux (other LSMs may grow to use it as well) rely on the 'iif' field to determine the receiving network interface of inbound packets. Unfortunately, at present this field is not preserved across a skb clone operation which can lead to garbage values if the cloned skb is sent back through the network stack. This patch corrects this problem by properly copying the 'iif' field in __skb_clone() and removing the 'iif' field assignment from skb_act_clone() since it is no longer needed. Also, while we are here, put the assignments in the same order as the offsets to reduce cacheline bounces. Signed-off-by: Paul Moore <paul.moore@hp.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-11-26[SKBUFF]: Free old skb properly in skb_morphHerbert Xu
The skb_morph function only freed the data part of the dst skb, but leaked the auxiliary data such as the netfilter fields. This patch fixes this by moving the relevant parts from __kfree_skb to skb_release_all and calling it in skb_morph. It also makes kfree_skbmem static since it's no longer called anywhere else and it now no longer does skb_release_data. Thanks to Yasuyuki KOZAKAI for finding this problem and posting a patch for it. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2007-11-02[SG] Get rid of __sg_mark_end()Jens Axboe
sg_mark_end() overwrites the page_link information, but all users want __sg_mark_end() behaviour where we just set the end bit. That is the most natural way to use the sg list, since you'll fill it in and then mark the end point. So change sg_mark_end() to only set the termination bit. Add a sg_magic debug check as well, and clear a chain pointer if it is set. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-10-30[NET]: Fix incorrect sg_mark_end() calls.David S. Miller
This fixes scatterlist corruptions added by commit 68e3f5dd4db62619fdbe520d36c9ebf62e672256 [CRYPTO] users: Fix up scatterlist conversion errors The issue is that the code calls sg_mark_end() which clobbers the sg_page() pointer of the final scatterlist entry. The first part fo the fix makes skb_to_sgvec() do __sg_mark_end(). After considering all skb_to_sgvec() call sites the most correct solution is to call __sg_mark_end() in skb_to_sgvec() since that is what all of the callers would end up doing anyways. I suspect this might have fixed some problems in virtio_net which is the sole non-crypto user of skb_to_sgvec(). Other similar sg_mark_end() cases were converted over to __sg_mark_end() as well. Arguably sg_mark_end() is a poorly named function because it doesn't just "mark", it clears out the page pointer as a side effect, which is what led to these bugs in the first place. The one remaining plain sg_mark_end() call is in scsi_alloc_sgtable() and arguably it could be converted to __sg_mark_end() if only so that we can delete this confusing interface from linux/scatterlist.h Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-26[NET_CLS_ACT]: Use skb_act_cloneJamal Hadi Salim
clean skb_clone of any signs of CONFIG_NET_CLS_ACT and have mirred us skb_act_clone() Signed-off-by: Jamal Hadi Salim <hadi@cyberus.ca> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-24SG: Change sg_set_page() to take length and offset argumentJens Axboe
Most drivers need to set length and offset as well, so may as well fold those three lines into one. Add sg_assign_page() for those two locations that only needed to set the page, where the offset/length is set outside of the function context. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-10-22Update net/ to use sg helpersJens Axboe
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-10-15[NET]: Fix csum_start update in pskb_expand_headHerbert Xu
I got confused by the dual nature of the off variable in the function pskb_expand_head. The csum_start offset should use nhead instead of off which can change depending on whether we are using offsets or pointers. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-15[SKBUFF]: Add skb_morphHerbert Xu
This patch creates a new function skb_morph that's just like skb_clone except that it lets user provide the spare skb that will be overwritten by the one that's to be cloned. This will be used by IP fragment reassembly so that we get back the same skb that went in last (rather than the head skb that we get now which requires us to carry around double pointers all over the place). Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-15[SKBUFF]: Merge common code between copy_skb_header and skb_cloneHerbert Xu
This patch creates a new function __copy_skb_header to merge the common code between copy_skb_header and skb_clone. Having two functions which are largely the same is a source of wasted labour as well as confusion. In fact the tc_verd stuff is almost certainly a bug since it's treated differently in skb_clone compared to the callers of copy_skb_header (skb_copy/pskb_copy/skb_copy_expand). I've kept that difference in tact with a comment added asking for clarification. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10[SKBUFF]: Fix up csum_start when head room changesHerbert Xu
Thanks for noticing the bug where csum_start is not updated when the head room changes. This patch fixes that. It also moves the csum/ip_summed copying into copy_skb_header so that skb_copy_expand gets it too. I've checked its callers and no one should be upset by this. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-20mm: Remove slab destructors from kmem_cache_create().Paul Mundt
Slab destructors were no longer supported after Christoph's c59def9f222d44bb7e2f0a559f2906191a0862d7 change. They've been BUGs for both slab and slub, and slob never supported them either. This rips out support for the dtor pointer from kmem_cache_create() completely and fixes up every single callsite in the kernel (there were about 224, not including the slab allocator definitions themselves, or the documentation references). Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-07-10[NETFILTER]: x_tables: add TRACE targetJozsef Kadlecsik
The TRACE target can be used to follow IP and IPv6 packets through the ruleset. Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu> Signed-off-by: Patrick NcHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10[CORE] Stack changes to add multiqueue hardware support APIPeter P Waskiewicz Jr
Add the multiqueue hardware device support API to the core network stack. Allow drivers to allocate multiple queues and manage them at the netdev level if they choose to do so. Added a new field to sk_buff, namely queue_mapping, for drivers to know which tx_ring to select based on OS classification of the flow. Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com> Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-10[SKBUFF]: Keep track of writable header len of headerless clonesPatrick McHardy
Currently NAT (and others) that want to modify cloned skbs copy them, even if in the vast majority of cases its not necessary because the skb is a clone made by TCP and the portion NAT wants to modify is actually writable because TCP release the header reference before cloning. The problem is that there is no clean way for NAT to find out how long the writable header area is, so this patch introduces skb->hdr_len to hold this length. When a headerless skb is cloned skb->hdr_len is set to the current headroom, for regular clones it is copied from the original. A new function skb_clone_writable(skb, len) returns whether the skb is writable up to len bytes from skb->data. To avoid enlarging the skb the mac_len field is reduced to 16 bit and the new hdr_len field is put in the remaining 16 bit. I've done a few rough benchmarks of NAT (not with this exact patch, but a very similar one). As expected it saves huge amounts of system time in case of sendfile, bringing it down to basically the same amount as without NAT, with sendmsg it only helps on loopback, probably because of the large MTU. Transmit a 1GB file using sendfile/sendmsg over eth0/lo with and without NAT: - sendfile eth0, no NAT: sys 0m0.388s - sendfile eth0, NAT: sys 0m1.835s - sendfile eth0: NAT + path: sys 0m0.370s (~ -80%) - sendfile lo, no NAT: sys 0m0.258s - sendfile lo, NAT: sys 0m2.609s - sendfile lo, NAT + patch: sys 0m0.260s (~ -90%) - sendmsg eth0, no NAT: sys 0m2.508s - sendmsg eth0, NAT: sys 0m2.539s - sendmsg eth0, NAT + patch: sys 0m2.445s (no change) - sendmsg lo, no NAT: sys 0m2.151s - sendmsg lo, NAT: sys 0m3.557s - sendmsg lo, NAT + patch: sys 0m2.159s (~ -40%) I expect other users can see a similar performance improvement, packet mangling iptables targets, ipip and ip_gre come to mind .. Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>