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* net: ipv6: fix TCP early demuxEric Dumazet2012-08-061-1/+3
| | | | | | | | | | IPv6 needs a cookie in dst_check() call. We need to add rx_dst_cookie and provide a family independent sk_rx_dst_set(sk, skb) method to properly support IPv6 TCP early demux. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* Merge branch 'akpm' (Andrew's patch-bomb)Linus Torvalds2012-08-011-10/+11
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Merge Andrew's second set of patches: - MM - a few random fixes - a couple of RTC leftovers * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (120 commits) rtc/rtc-88pm80x: remove unneed devm_kfree rtc/rtc-88pm80x: assign ret only when rtc_register_driver fails mm: hugetlbfs: close race during teardown of hugetlbfs shared page tables tmpfs: distribute interleave better across nodes mm: remove redundant initialization mm: warn if pg_data_t isn't initialized with zero mips: zero out pg_data_t when it's allocated memcg: gix memory accounting scalability in shrink_page_list mm/sparse: remove index_init_lock mm/sparse: more checks on mem_section number mm/sparse: optimize sparse_index_alloc memcg: add mem_cgroup_from_css() helper memcg: further prevent OOM with too many dirty pages memcg: prevent OOM with too many dirty pages mm: mmu_notifier: fix freed page still mapped in secondary MMU mm: memcg: only check anon swapin page charges for swap cache mm: memcg: only check swap cache pages for repeated charging mm: memcg: split swapin charge function into private and public part mm: memcg: remove needless !mm fixup to init_mm when charging mm: memcg: remove unneeded shmem charge type ...
| * netvm: prevent a stream-specific deadlockMel Gorman2012-08-011-10/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch series is based on top of "Swap-over-NBD without deadlocking v15" as it depends on the same reservation of PF_MEMALLOC reserves logic. When a user or administrator requires swap for their application, they create a swap partition and file, format it with mkswap and activate it with swapon. In diskless systems this is not an option so if swap if required then swapping over the network is considered. The two likely scenarios are when blade servers are used as part of a cluster where the form factor or maintenance costs do not allow the use of disks and thin clients. The Linux Terminal Server Project recommends the use of the Network Block Device (NBD) for swap but this is not always an option. There is no guarantee that the network attached storage (NAS) device is running Linux or supports NBD. However, it is likely that it supports NFS so there are users that want support for swapping over NFS despite any performance concern. Some distributions currently carry patches that support swapping over NFS but it would be preferable to support it in the mainline kernel. Patch 1 avoids a stream-specific deadlock that potentially affects TCP. Patch 2 is a small modification to SELinux to avoid using PFMEMALLOC reserves. Patch 3 adds three helpers for filesystems to handle swap cache pages. For example, page_file_mapping() returns page->mapping for file-backed pages and the address_space of the underlying swap file for swap cache pages. Patch 4 adds two address_space_operations to allow a filesystem to pin all metadata relevant to a swapfile in memory. Upon successful activation, the swapfile is marked SWP_FILE and the address space operation ->direct_IO is used for writing and ->readpage for reading in swap pages. Patch 5 notes that patch 3 is bolting filesystem-specific-swapfile-support onto the side and that the default handlers have different information to what is available to the filesystem. This patch refactors the code so that there are generic handlers for each of the new address_space operations. Patch 6 adds an API to allow a vector of kernel addresses to be translated to struct pages and pinned for IO. Patch 7 adds support for using highmem pages for swap by kmapping the pages before calling the direct_IO handler. Patch 8 updates NFS to use the helpers from patch 3 where necessary. Patch 9 avoids setting PF_private on PG_swapcache pages within NFS. Patch 10 implements the new swapfile-related address_space operations for NFS and teaches the direct IO handler how to manage kernel addresses. Patch 11 prevents page allocator recursions in NFS by using GFP_NOIO where appropriate. Patch 12 fixes a NULL pointer dereference that occurs when using swap-over-NFS. With the patches applied, it is possible to mount a swapfile that is on an NFS filesystem. Swap performance is not great with a swap stress test taking roughly twice as long to complete than if the swap device was backed by NBD. This patch: netvm: prevent a stream-specific deadlock It could happen that all !SOCK_MEMALLOC sockets have buffered so much data that we're over the global rmem limit. This will prevent SOCK_MEMALLOC buffers from receiving data, which will prevent userspace from running, which is needed to reduce the buffered data. Fix this by exempting the SOCK_MEMALLOC sockets from the rmem limit. Once this change it applied, it is important that sockets that set SOCK_MEMALLOC do not clear the flag until the socket is being torn down. If this happens, a warning is generated and the tokens reclaimed to avoid accounting errors until the bug is fixed. [davem@davemloft.net: Warning about clearing SOCK_MEMALLOC] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Rik van Riel <riel@redhat.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Cc: Neil Brown <neilb@suse.de> Cc: Christoph Hellwig <hch@infradead.org> Cc: Mike Christie <michaelc@cs.wisc.edu> Cc: Eric B Munson <emunson@mgebm.net> Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | net: ipv4: fix RCU races on dst refcountsEric Dumazet2012-07-301-2/+1Star
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | commit c6cffba4ffa2 (ipv4: Fix input route performance regression.) added various fatal races with dst refcounts. crashes happen on tcp workloads if routes are added/deleted at the same time. The dst_free() calls from free_fib_info_rcu() are clearly racy. We need instead regular dst refcounting (dst_release()) and make sure dst_release() is aware of RCU grace periods : Add DST_RCU_FREE flag so that dst_release() respects an RCU grace period before dst destruction for cached dst Introduce a new inet_sk_rx_dst_set() helper, using atomic_inc_not_zero() to make sure we dont increase a zero refcount (On a dst currently waiting an rcu grace period before destruction) rt_cache_route() must take a reference on the new cached route, and release it if was not able to install it. With this patch, my machines survive various benchmarks. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: perform DMA to userspace only if there is a task waiting for itJiri Kosina2012-07-271-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Back in 2006, commit 1a2449a87b ("[I/OAT]: TCP recv offload to I/OAT") added support for receive offloading to IOAT dma engine if available. The code in tcp_rcv_established() tries to perform early DMA copy if applicable. It however does so without checking whether the userspace task is actually expecting the data in the buffer. This is not a problem under normal circumstances, but there is a corner case where this doesn't work -- and that's when MSG_TRUNC flag to recvmsg() is used. If the IOAT dma engine is not used, the code properly checks whether there is a valid ucopy.task and the socket is owned by userspace, but misses the check in the dmaengine case. This problem can be observed in real trivially -- for example 'tbench' is a good reproducer, as it makes a heavy use of MSG_TRUNC. On systems utilizing IOAT, you will soon find tbench waiting indefinitely in sk_wait_data(), as they have been already early-copied in tcp_rcv_established() using dma engine. This patch introduces the same check we are performing in the simple iovec copy case to the IOAT case as well. It fixes the indefinite recvmsg(MSG_TRUNC) hangs. Signed-off-by: Jiri Kosina <jkosina@suse.cz> Signed-off-by: David S. Miller <davem@davemloft.net>
* ipv4: fix TCP early demuxEric Dumazet2012-07-271-0/+1
| | | | | | | | | | | commit 92101b3b2e317 (ipv4: Prepare for change of rt->rt_iif encoding.) invalidated TCP early demux, because rx_dst_ifindex is not properly initialized and checked. Also remove the use of inet_iif(skb) in favor or skb->skb_iif Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* ipv4: Prepare for change of rt->rt_iif encoding.David S. Miller2012-07-241-12/+0Star
| | | | | | | | | | | | | | | | | | | | | | Use inet_iif() consistently, and for TCP record the input interface of cached RX dst in inet sock. rt->rt_iif is going to be encoded differently, so that we can legitimately cache input routes in the FIB info more aggressively. When the input interface is "use SKB device index" the rt->rt_iif will be set to zero. This forces us to move the TCP RX dst cache installation into the ipv4 specific code, and as well it should since doing the route caching for ipv6 is pointless at the moment since it is not inspected in the ipv6 input paths yet. Also, remove the unlikely on dst->obsolete, all ipv4 dsts have obsolete set to a non-zero value to force invocation of the check callback. Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: Return bool instead of int where appropriateVijay Subramanian2012-07-201-8/+8
| | | | | | | | Applied to a set of static inline functions in tcp_input.c Signed-off-by: Vijay Subramanian <subramanian.vijay@gmail.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* net-tcp: Fast Open client - cookie-less modeYuchung Cheng2012-07-191-2/+6
| | | | | | | | | | | In trusted networks, e.g., intranet, data-center, the client does not need to use Fast Open cookie to mitigate DoS attacks. In cookie-less mode, sendmsg() with MSG_FASTOPEN flag will send SYN-data regardless of cookie availability. Signed-off-by: Yuchung Cheng <ycheng@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* net-tcp: Fast Open client - detecting SYN-data dropsYuchung Cheng2012-07-191-1/+9
| | | | | | | | | | | | | | | | | | On paths with firewalls dropping SYN with data or experimental TCP options, Fast Open connections will have experience SYN timeout and bad performance. The solution is to track such incidents in the cookie cache and disables Fast Open temporarily. Since only the original SYN includes data and/or Fast Open option, the SYN-ACK has some tell-tale sign (tcp_rcv_fastopen_synack()) to detect such drops. If a path has recurring Fast Open SYN drops, Fast Open is disabled for 2^(recurring_losses) minutes starting from four minutes up to roughly one and half day. sendmsg with MSG_FASTOPEN flag will succeed but it behaves as connect() then write(). Signed-off-by: Yuchung Cheng <ycheng@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* net-tcp: Fast Open client - receiving SYN-ACKYuchung Cheng2012-07-191-5/+35
| | | | | | | | | | | On receiving the SYN-ACK after SYN-data, the client needs to a) update the cached MSS and cookie (if included in SYN-ACK) b) retransmit the data not yet acknowledged by the SYN-ACK in the final ACK of the handshake. Signed-off-by: Yuchung Cheng <ycheng@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* net-tcp: Fast Open baseYuchung Cheng2012-07-191-4/+22
| | | | | | | | | | | | | | | | | | | | | | This patch impelements the common code for both the client and server. 1. TCP Fast Open option processing. Since Fast Open does not have an option number assigned by IANA yet, it shares the experiment option code 254 by implementing draft-ietf-tcpm-experimental-options with a 16 bits magic number 0xF989. This enables global experiments without clashing the scarce(2) experimental options available for TCP. When the draft status becomes standard (maybe), the client should switch to the new option number assigned while the server supports both numbers for transistion. 2. The new sysctl tcp_fastopen 3. A place holder init function Signed-off-by: Yuchung Cheng <ycheng@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: refine SYN handling in tcp_validate_incomingEric Dumazet2012-07-181-1/+5
| | | | | | | | | | | | | | | | | Followup of commit 0c24604b68fc (tcp: implement RFC 5961 4.2) As reported by Vijay Subramanian, we should send a challenge ACK instead of a dup ack if a SYN flag is set on a packet received out of window. This permits the ratelimiting to work as intended, and to increase correct SNMP counters. Suggested-by: Vijay Subramanian <subramanian.vijay@gmail.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Vijay Subramanian <subramanian.vijay@gmail.com> Cc: Kiran Kumar Kella <kkiran@broadcom.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: implement RFC 5961 4.2Eric Dumazet2012-07-171-17/+15Star
| | | | | | | | | | | | | | | | | | | Implement the RFC 5691 mitigation against Blind Reset attack using SYN bit. Section 4.2 of RFC 5961 advises to send a Challenge ACK and drop incoming packet, instead of resetting the session. Add a new SNMP counter to count number of challenge acks sent in response to SYN packets. (netstat -s | grep TCPSYNChallenge) Remove obsolete TCPAbortOnSyn, since we no longer abort a TCP session because of a SYN flag. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Kiran Kumar Kella <kkiran@broadcom.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: implement RFC 5961 3.2Eric Dumazet2012-07-171-1/+30
| | | | | | | | | | | | | | | | | | | | | | | Implement the RFC 5691 mitigation against Blind Reset attack using RST bit. Idea is to validate incoming RST sequence, to match RCV.NXT value, instead of previouly accepted window : (RCV.NXT <= SEG.SEQ < RCV.NXT+RCV.WND) If sequence is in window but not an exact match, send a "challenge ACK", so that the other part can resend an RST with the appropriate sequence. Add a new sysctl, tcp_challenge_ack_limit, to limit number of challenge ACK sent per second. Add a new SNMP counter to count number of challenge acks sent. (netstat -s | grep TCPChallengeACK) Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Kiran Kumar Kella <kkiran@broadcom.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: add OFO snmp countersEric Dumazet2012-07-171-2/+5
| | | | | | | | | | | | | | | | | Add three SNMP TCP counters, to better track TCP behavior at global stage (netstat -s), when packets are received Out Of Order (OFO) TCPOFOQueue : Number of packets queued in OFO queue TCPOFODrop : Number of packets meant to be queued in OFO but dropped because socket rcvbuf limit hit. TCPOFOMerge : Number of packets in OFO that were merged with other packets. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: Move dynamnic metrics handling into seperate file.David S. Miller2012-07-111-186/+2Star
| | | | Signed-off-by: David S. Miller <davem@davemloft.net>
* net: Do delayed neigh confirmation.David S. Miller2012-07-051-6/+13
| | | | | | | | | | | | | | When a dst_confirm() happens, mark the confirmation as pending in the dst. Then on the next packet out, when we have the neigh in-hand, do the update. This removes the dependency in dst_confirm() of dst's having an attached neigh. While we're here, remove the explicit 'dst' NULL check, all except 2 or 3 call sites ensure it's not NULL. So just fix those cases up. Signed-off-by: David S. Miller <davem@davemloft.net>
* ipv4: Early TCP socket demux.David S. Miller2012-06-201-1/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Input packet processing for local sockets involves two major demuxes. One for the route and one for the socket. But we can optimize this down to one demux for certain kinds of local sockets. Currently we only do this for established TCP sockets, but it could at least in theory be expanded to other kinds of connections. If a TCP socket is established then it's identity is fully specified. This means that whatever input route was used during the three-way handshake must work equally well for the rest of the connection since the keys will not change. Once we move to established state, we cache the receive packet's input route to use later. Like the existing cached route in sk->sk_dst_cache used for output packets, we have to check for route invalidations using dst->obsolete and dst->ops->check(). Early demux occurs outside of a socket locked section, so when a route invalidation occurs we defer the fixup of sk->sk_rx_dst until we are actually inside of established state packet processing and thus have the socket locked. Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: take care of overlaps in tcp_try_coalesce()Eric Dumazet2012-05-241-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | Sergio Correia reported following warning : WARNING: at net/ipv4/tcp.c:1301 tcp_cleanup_rbuf+0x4f/0x110() WARN(skb && !before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq), "cleanup rbuf bug: copied %X seq %X rcvnxt %X\n", tp->copied_seq, TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt); It appears TCP coalescing, and more specifically commit b081f85c297 (net: implement tcp coalescing in tcp_queue_rcv()) should take care of possible segment overlaps in receive queue. This was properly done in the case of out_or_order_queue by the caller. For example, segment at tail of queue have sequence 1000-2000, and we add a segment with sequence 1500-2500. This can happen in case of retransmits. In this case, just don't do the coalescing. Reported-by: Sergio Correia <lists@uece.net> Signed-off-by: Eric Dumazet <edumazet@google.com> Tested-by: Sergio Correia <lists@uece.net> Signed-off-by: David S. Miller <davem@davemloft.net>
* net: introduce skb_try_coalesce()Eric Dumazet2012-05-201-64/+3Star
| | | | | | | | | | | | | | | | | | | Move tcp_try_coalesce() protocol independent part to skb_try_coalesce(). skb_try_coalesce() can be used in IPv4 defrag and IPv6 reassembly, to build optimized skbs (less sk_buff, and possibly less 'headers') skb_try_coalesce() is zero copy, unless the copy can fit in destination header (its a rare case) kfree_skb_partial() is also moved to net/core/skbuff.c and exported, because IPv6 will need it in patch (ipv6: use skb coalescing in reassembly). Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Alexander Duyck <alexander.h.duyck@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: bool conversionsEric Dumazet2012-05-171-106/+108
| | | | | | | | | | | bool conversions where possible. __inline__ -> inline space cleanups Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* net: ipv4 and ipv6: Convert printk(KERN_DEBUG to pr_debugJoe Perches2012-05-161-24/+24
| | | | | | | Use the current debugging style and enable dynamic_debug. Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* net: Convert net_ratelimit uses to net_<level>_ratelimitedJoe Perches2012-05-151-4/+3Star
| | | | | | | | | | Standardize the net core ratelimited logging functions. Coalesce formats, align arguments. Change a printk then vprintk sequence to use printf extension %pV. Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: Out-line tcp_try_rmem_schedulePavel Emelyanov2012-05-111-1/+1
| | | | | | | | | | | | | | | | | | As proposed by Eric, make the tcp_input.o thinner. add/remove: 1/1 grow/shrink: 1/4 up/down: 868/-1329 (-461) function old new delta tcp_try_rmem_schedule - 864 +864 tcp_ack 4811 4815 +4 tcp_validate_incoming 817 815 -2 tcp_collapse 860 858 -2 tcp_send_rcvq 555 353 -202 tcp_data_queue 3435 3033 -402 tcp_prune_queue 721 - -721 Signed-off-by: Pavel Emelyanov <xemul@parallels.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: Schedule rmem for rcvq repair sendPavel Emelyanov2012-05-111-0/+3
| | | | | | | | | | As noted by Eric, no checks are performed on the data size we're putting in the read queue during repair. Thus, validate the given data size with the common rmem management routine. Signed-off-by: Pavel Emelyanov <xemul@parallels.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: Move rcvq sending to tcp_input.cPavel Emelyanov2012-05-111-1/+34
| | | | | | | | | It actually works on the input queue and will use its read mem routines, thus it's better to have in in the tcp_input.c file. Signed-off-by: Pavel Emelyanov <xemul@parallels.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller2012-05-081-5/+8
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Conflicts: drivers/net/ethernet/intel/e1000e/param.c drivers/net/wireless/iwlwifi/iwl-agn-rx.c drivers/net/wireless/iwlwifi/iwl-trans-pcie-rx.c drivers/net/wireless/iwlwifi/iwl-trans.h Resolved the iwlwifi conflict with mainline using 3-way diff posted by John Linville and Stephen Rothwell. In 'net' we added a bug fix to make iwlwifi report a more accurate skb->truesize but this conflicted with RX path changes that happened meanwhile in net-next. In e1000e a conflict arose in the validation code for settings of adapter->itr. 'net-next' had more sophisticated logic so that logic was used. Signed-off-by: David S. Miller <davem@davemloft.net>
| * tcp: change tcp_adv_win_scale and tcp_rmem[2]Eric Dumazet2012-05-031-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | tcp_adv_win_scale default value is 2, meaning we expect a good citizen skb to have skb->len / skb->truesize ratio of 75% (3/4) In 2.6 kernels we (mis)accounted for typical MSS=1460 frame : 1536 + 64 + 256 = 1856 'estimated truesize', and 1856 * 3/4 = 1392. So these skbs were considered as not bloated. With recent truesize fixes, a typical MSS=1460 frame truesize is now the more precise : 2048 + 256 = 2304. But 2304 * 3/4 = 1728. So these skb are not good citizen anymore, because 1460 < 1728 (GRO can escape this problem because it build skbs with a too low truesize.) This also means tcp advertises a too optimistic window for a given allocated rcvspace : When receiving frames, sk_rmem_alloc can hit sk_rcvbuf limit and we call tcp_prune_queue()/tcp_collapse() too often, especially when application is slow to drain its receive queue or in case of losses (netperf is fast, scp is slow). This is a major latency source. We should adjust the len/truesize ratio to 50% instead of 75% This patch : 1) changes tcp_adv_win_scale default to 1 instead of 2 2) increase tcp_rmem[2] limit from 4MB to 6MB to take into account better truesize tracking and to allow autotuning tcp receive window to reach same value than before. Note that same amount of kernel memory is consumed compared to 2.6 kernels. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Neal Cardwell <ncardwell@google.com> Cc: Tom Herbert <therbert@google.com> Cc: Yuchung Cheng <ycheng@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
| * tcp: fix infinite cwnd in tcp_complete_cwr()Yuchung Cheng2012-04-301-3/+6
| | | | | | | | | | | | | | | | | | | | | | | | When the cwnd reduction is done, ssthresh may be infinite if TCP enters CWR via ECN or F-RTO. If cwnd is not undone, i.e., undo_marker is set, tcp_complete_cwr() falsely set cwnd to the infinite ssthresh value. The correct operation is to keep cwnd intact because it has been updated in ECN or F-RTO. Signed-off-by: Yuchung Cheng <ycheng@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
| * tcp: clean up use of jiffies in tcp_rcv_rtt_measure()Neal Cardwell2012-04-271-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | Clean up a reference to jiffies in tcp_rcv_rtt_measure() that should instead reference tcp_time_stamp. Since the result of the subtraction is passed into a function taking u32, this should not change any behavior (and indeed the generated assembly does not change on x86_64). However, it seems worth cleaning this up for consistency and clarity (and perhaps to avoid bugs if this is copied and pasted somewhere else). Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* | skb: Add skb_head_is_locked helper functionAlexander Duyck2012-05-031-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | This patch adds support for a skb_head_is_locked helper function. It is meant to be used any time we are considering transferring the head from skb->head to a paged frag. If the head is locked it means we cannot remove the head from the skb so it must be copied or we must take the skb as a whole. Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* | tcp: move stats merge to the end of tcp_try_coalesceAlexander Duyck2012-05-031-26/+29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This change cleans up the last bits of tcp_try_coalesce so that we only need one goto which jumps to the end of the function. The idea is to make the code more readable by putting things in a linear order so that we start execution at the top of the function, and end it at the bottom. I also made a slight tweak to the code for handling frags when we are a clone. Instead of making it an if (clone) loop else nr_frags = 0 I changed the logic so that if (!clone) we just set the number of frags to 0 which disables the for loop anyway. Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* | tcp: Move code related to head frag in tcp_try_coalesceAlexander Duyck2012-05-031-17/+25
| | | | | | | | | | | | | | | | | | | | | | | | This change reorders the code related to the use of an skb->head_frag so it is placed before we check the rest of the frags. This allows the code to read more linearly instead of like some sort of loop. Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* | tcp: Fix truesize accounting in tcp_try_coalesceAlexander Duyck2012-05-031-6/+4Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch addresses several issues in the way we were tracking the truesize in tcp_try_coalesce. First it was using ksize which prevents us from having a 0 sized head frag and getting a usable result. To resolve that this patch uses the end pointer which is set based off either ksize, or the frag_size supplied in build_skb. This allows us to compute the original truesize of the entire buffer and remove that value leaving us with just what was added as pages. The second issue was the use of skb->len if there is a mergeable head frag. We should only need to remove the size of an data aligned sk_buff from our current skb->truesize to compute the delta for a buffer with a reused head. By using skb->len the value of truesize was being artificially reduced which means that head frags could use more memory than buffers using standard allocations. Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* | net: Stop decapitating clones that have a head_fragAlexander Duyck2012-05-031-7/+2Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This change is meant ot prevent stealing the skb->head to use as a page in the event that the skb->head was cloned. This allows the other clones to track each other via shinfo->dataref. Without this we break down to two methods for tracking the reference count, one being dataref, the other being the page count. As a result it becomes difficult to track how many references there are to skb->head. Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* | net: implement tcp coalescing in tcp_queue_rcv()Eric Dumazet2012-05-031-19/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Extend tcp coalescing implementing it from tcp_queue_rcv(), the main receiver function when application is not blocked in recvmsg(). Function tcp_queue_rcv() is moved a bit to allow its call from tcp_data_queue() This gives good results especially if GRO could not kick, and if skb head is a fragment. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Alexander Duyck <alexander.h.duyck@intel.com> Cc: Neal Cardwell <ncardwell@google.com> Cc: Tom Herbert <therbert@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* | net: take care of cloned skbs in tcp_try_coalesce()Eric Dumazet2012-05-031-14/+28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Before stealing fragments or skb head, we must make sure skbs are not cloned. Alexander was worried about destination skb being cloned : In bridge setups, a driver could be fooled if skb->data_len would not match skb nr_frags. If source skb is cloned, we must take references on pages instead. Bug happened using tcpdump (if not using mmap()) Introduce kfree_skb_partial() helper to cleanup code. Reported-by: Alexander Duyck <alexander.h.duyck@intel.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* | tcp: early retransmit: delayed fast retransmitYuchung Cheng2012-05-031-7/+62
| | | | | | | | | | | | | | | | | | | | | | | | | | Implementing the advanced early retransmit (sysctl_tcp_early_retrans==2). Delays the fast retransmit by an interval of RTT/4. We borrow the RTO timer to implement the delay. If we receive another ACK or send a new packet, the timer is cancelled and restored to original RTO value offset by time elapsed. When the delayed-ER timer fires, we enter fast recovery and perform fast retransmit. Signed-off-by: Yuchung Cheng <ycheng@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* | tcp: early retransmitYuchung Cheng2012-05-031-0/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch implements RFC 5827 early retransmit (ER) for TCP. It reduces DUPACK threshold (dupthresh) if outstanding packets are less than 4 to recover losses by fast recovery instead of timeout. While the algorithm is simple, small but frequent network reordering makes this feature dangerous: the connection repeatedly enter false recovery and degrade performance. Therefore we implement a mitigation suggested in the appendix of the RFC that delays entering fast recovery by a small interval, i.e., RTT/4. Currently ER is conservative and is disabled for the rest of the connection after the first reordering event. A large scale web server experiment on the performance impact of ER is summarized in section 6 of the paper "Proportional Rate Reduction for TCP”, IMC 2011. http://conferences.sigcomm.org/imc/2011/docs/p155.pdf Note that Linux has a similar feature called THIN_DUPACK. The differences are THIN_DUPACK do not mitigate reorderings and is only used after slow start. Currently ER is disabled if THIN_DUPACK is enabled. I would be happy to merge THIN_DUPACK feature with ER if people think it's a good idea. ER is enabled by sysctl_tcp_early_retrans: 0: Disables ER 1: Reduce dupthresh to packets_out - 1 when outstanding packets < 4. 2: (Default) reduce dupthresh like mode 1. In addition, delay entering fast recovery by RTT/4. Note: mode 2 is implemented in the third part of this patch series. Signed-off-by: Yuchung Cheng <ycheng@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* | tcp: early retransmit: tcp_enter_recovery()Yuchung Cheng2012-05-031-27/+34
| | | | | | | | | | | | | | | | | | | | This a prepartion patch that refactors the code to enter recovery into a new function tcp_enter_recovery(). It's needed to implement the delayed fast retransmit in ER. Signed-off-by: Yuchung Cheng <ycheng@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* | tcp: makes tcp_try_coalesce aware of skb->head_fragEric Dumazet2012-05-011-12/+43
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | TCP coalesce can check if skb to be merged has its skb->head mapped to a page fragment, instead of a kmalloc() area. We had to disable coalescing in this case, for performance reasons. We 'upgrade' skb->head as a fragment in itself. This reduces number of cache misses when user makes its copies, since a less sk_buff are fetched. This makes receive and ofo queues shorter and thus reduce cache line misses in TCP stack. This is a followup of patch "net: allow skb->head to be a page fragment" Tested with tg3 nic, with GRO on or off. We can see "TCPRcvCoalesce" counter being incremented. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Maciej Żenczykowski <maze@google.com> Cc: Neal Cardwell <ncardwell@google.com> Cc: Tom Herbert <therbert@google.com> Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com> Cc: Ben Hutchings <bhutchings@solarflare.com> Cc: Matt Carlson <mcarlson@broadcom.com> Cc: Michael Chan <mchan@broadcom.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* | tcp: tcp_try_coalesce returns a booleanEric Dumazet2012-04-241-9/+9
| | | | | | | | | | | | | | | | This clarifies code intention, as suggested by David. Suggested-by: David Miller <davem@davemloft.net> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* | Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller2012-04-241-0/+1
|\| | | | | | | | | | | | | | | | | | | | | | | | | Fix merge between commit 3adadc08cc1e ("net ax25: Reorder ax25_exit to remove races") and commit 0ca7a4c87d27 ("net ax25: Simplify and cleanup the ax25 sysctl handling") The former moved around the sysctl register/unregister calls, the later simply removed them. With help from Stephen Rothwell. Signed-off-by: David S. Miller <davem@davemloft.net>
| * tcp: fix tcp_grow_window() for large incoming framesEric Dumazet2012-04-181-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | tcp_grow_window() has to grow rcv_ssthresh up to window_clamp, allowing sender to increase its window. tcp_grow_window() still assumes a tcp frame is under MSS, but its no longer true with LRO/GRO. This patch fixes one of the performance issue we noticed with GRO on. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Neal Cardwell <ncardwell@google.com> Cc: Tom Herbert <therbert@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* | tcp: introduce tcp_try_coalesceEric Dumazet2012-04-241-17/+62
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit c8628155ece3 (tcp: reduce out_of_order memory use) took care of coalescing tcp segments provided by legacy devices (linear skbs) We extend this idea to fragged skbs, as their truesize can be heavy. ixgbe for example uses 256+1024+PAGE_SIZE/2 = 3328 bytes per segment. Use this coalescing strategy for receive queue too. This contributes to reduce number of tcp collapses, at minimal cost, and reduces memory overhead and packets drops. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Neal Cardwell <ncardwell@google.com> Cc: Tom Herbert <therbert@google.com> Cc: Maciej Żenczykowski <maze@google.com> Cc: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* | tcp: Move code aroundPavel Emelyanov2012-04-211-33/+48
| | | | | | | | | | | | | | | | This is just the preparation patch, which makes the needed for TCP repair code ready for use. Signed-off-by: Pavel Emelyanov <xemul@parallels.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* | net: cleanup unsigned to unsigned intEric Dumazet2012-04-151-1/+1
| | | | | | | | | | | | | | Use of "unsigned int" is preferred to bare "unsigned" in net tree. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* | tcp: Remove redundant code entering quickack modeVijay Subramanian2012-04-141-2/+0Star
| | | | | | | | | | | | | | | | | | tcp_enter_quickack_mode() already calls tcp_incr_quickack() and sets icsk->icsk_ack.ato to TCP_ATO_MIN. This patch removes the duplication. Signed-off-by: Vijay Subramanian <subramanian.vijay@gmail.com> Reviewed-by: Flavio Leitner <fbl@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* | tcp: RFC6298 supersedes RFC2988bisEric Dumazet2012-04-141-2/+2
|/ | | | | | | | | Updates some comments to track RFC6298 Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: H.K. Jerry Chu <hkchu@google.com> Cc: Tom Herbert <therbert@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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