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e0f9759f53
linux/net/ipv4
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Eric Dumazet e0f9759f53 tcp: try to keep packet if SYN_RCV race is lost 
배석진 reported that in some situations, packets for a given 5-tuple
end up being processed by different CPUS.

This involves RPS, and fragmentation.

배석진 is seeing packet drops when a SYN_RECV request socket is
moved into ESTABLISH state. Other states are protected by socket lock.

This is caused by a CPU losing the race, and simply not caring enough.

Since this seems to occur frequently, we can do better and perform
a second lookup.

Note that all needed memory barriers are already in the existing code,
thanks to the spin_lock()/spin_unlock() pair in inet_ehash_insert()
and reqsk_put(). The second lookup must find the new socket,
unless it has already been accepted and closed by another cpu.

Note that the fragmentation could be avoided in the first place by
use of a correct TCP MSS option in the SYN{ACK} packet, but this
does not mean we can not be more robust.

Many thanks to 배석진 for a very detailed analysis.

Reported-by: 배석진 <soukjin.bae@samsung.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-02-14 14:21:45 -05:00
..
netfilter netfilter: nf_tables: fix flowtable free 2018-02-07 00:58:57 +01:00
af_inet.c net: Convert pernet_subsys, registered from inet_init() 2018-02-13 10:36:08 -05:00
ah4.c net: use -ENOSPC for transient busy indication 2017-11-03 22:11:17 +08:00
arp.c net: Convert pernet_subsys, registered from inet_init() 2018-02-13 10:36:08 -05:00
cipso_ipv4.c tcp/dccp: fix ireq->opt races 2017-10-21 01:33:19 +01:00
datagram.c
devinet.c net: Convert pernet_subsys, registered from inet_init() 2018-02-13 10:36:08 -05:00
esp4_offload.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-01-23 13:51:56 -05:00
esp4.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-01-17 00:10:42 -05:00
fib_frontend.c net: Convert pernet_subsys, registered from inet_init() 2018-02-13 10:36:08 -05:00
fib_lookup.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fib_notifier.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fib_rules.c net: fib_rules: Implement notification logic in core 2017-08-03 15:35:59 -07:00
fib_semantics.c net/ipv4: Unexport fib_multipath_hash and fib_select_path 2018-02-13 14:00:57 -05:00
fib_trie.c net: delete /proc THIS_MODULE references 2018-01-16 15:01:33 -05:00
fou.c gue: fix remcsum when GRO on and CHECKSUM_PARTIAL boundary is outer UDP 2017-08-01 16:09:14 -07:00
gre_demux.c
gre_offload.c gso: fix payload length when gso_size is zero 2017-10-08 10:12:15 -07:00
icmp.c net: Convert pernet_subsys, registered from inet_init() 2018-02-13 10:36:08 -05:00
igmp.c net: Convert pernet_subsys, registered from inet_init() 2018-02-13 10:36:08 -05:00
inet_connection_sock.c Revert "defer call to mem_cgroup_sk_alloc()" 2018-02-02 19:49:31 -05:00
inet_diag.c inet_diag: Add equal-operator for ports 2018-01-02 13:54:04 -05:00
inet_fragment.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2017-11-15 11:56:19 -08:00
inet_hashtables.c inet: Avoid unitialized variable warning in inet_unhash() 2018-02-01 09:48:42 -05:00
inet_timewait_sock.c net: Convert atomic_t net::count to refcount_t 2018-01-15 14:23:42 -05:00
inetpeer.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-10-05 18:19:22 -07:00
ip_forward.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ip_fragment.c net: Convert pernet_subsys, registered from inet_init() 2018-02-13 10:36:08 -05:00
ip_gre.c net: erspan: fix erspan config overwrite 2018-02-06 11:32:49 -05:00
ip_input.c IPv4: early demux can return an error code 2017-10-01 03:55:47 +01:00
ip_options.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ip_output.c udp: remove unreachable ufo branches 2017-08-22 14:27:18 -07:00
ip_sockglue.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf 2018-02-01 14:41:46 -05:00
ip_tunnel_core.c net: store port/representator id in metadata_dst 2017-06-25 11:42:01 -04:00
ip_tunnel.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-01-29 10:15:51 -05:00
ip_vti.c net: don't call update_pmtu unconditionally 2018-01-25 16:27:34 -05:00
ipcomp.c
ipconfig.c ipconfig: use dev_set_mtu() 2018-01-24 19:13:45 -05:00
ipip.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-10-30 21:09:24 +09:00
ipmr.c net: Convert pernet_subsys, registered from inet_init() 2018-02-13 10:36:08 -05:00
Kconfig ip: update policy routing config help 2017-10-12 22:57:11 -07:00
Makefile net: tcp: Remove TCP probe module 2018-01-02 14:27:29 -05:00
netfilter.c netfilter: remove struct nf_afinfo and its helper functions 2018-01-08 18:11:02 +01:00
ping.c net: Convert pernet_subsys, registered from inet_init() 2018-02-13 10:36:08 -05:00
proc.c net: Convert pernet_subsys, registered from inet_init() 2018-02-13 10:36:08 -05:00
protocol.c net: Add sysctl to toggle early demux for tcp and udp 2017-03-24 13:17:07 -07:00
raw_diag.c net: ipv6: add second dif to raw socket lookups 2017-08-07 11:39:22 -07:00
raw.c net: Convert pernet_subsys, registered from inet_init() 2018-02-13 10:36:08 -05:00
route.c net/ipv4: Unexport fib_multipath_hash and fib_select_path 2018-02-13 14:00:57 -05:00
syncookies.c tcp: Namespace-ify sysctl_tcp_workaround_signed_windows 2017-10-28 19:24:38 +09:00
sysctl_net_ipv4.c net: Convert ipv4_sysctl_ops 2018-02-13 10:36:09 -05:00
tcp_bbr.c tcp_bbr: fix pacing_gain to always be unity when using lt_bw 2018-02-01 09:43:38 -05:00
tcp_bic.c tcp: consolidate congestion control undo functions 2017-08-06 21:25:10 -07:00
tcp_cdg.c tcp: cdg: make struct tcp_cdg static 2017-10-16 21:24:25 +01:00
tcp_cong.c tcp: Namespace-ify sysctl_tcp_default_congestion_control 2017-11-15 14:09:52 +09:00
tcp_cubic.c tcp: consolidate congestion control undo functions 2017-08-06 21:25:10 -07:00
tcp_dctcp.c
tcp_diag.c net: sock: replace sk_state_load with inet_sk_state_load and remove sk_state_store 2017-12-20 14:00:25 -05:00
tcp_fastopen.c tcp: pause Fast Open globally after third consecutive timeout 2017-12-13 15:51:12 -05:00
tcp_highspeed.c tcp: consolidate congestion control undo functions 2017-08-06 21:25:10 -07:00
tcp_htcp.c tcp: fix cwnd undo in Reno and HTCP congestion controls 2017-08-06 21:25:10 -07:00
tcp_hybla.c
tcp_illinois.c tcp: consolidate congestion control undo functions 2017-08-06 21:25:10 -07:00
tcp_input.c tcp: try to keep packet if SYN_RCV race is lost 2018-02-14 14:21:45 -05:00
tcp_ipv4.c tcp: try to keep packet if SYN_RCV race is lost 2018-02-14 14:21:45 -05:00
tcp_lp.c tcp: switch TCP TS option (RFC 7323) to 1ms clock 2017-05-17 16:06:01 -04:00
tcp_metrics.c net: Convert pernet_subsys, registered from inet_init() 2018-02-13 10:36:08 -05:00
tcp_minisocks.c tcp: try to keep packet if SYN_RCV race is lost 2018-02-14 14:21:45 -05:00
tcp_nv.c tcp_nv: fix potential integer overflow in tcpnv_acked 2018-01-31 10:26:30 -05:00
tcp_offload.c gso: validate gso_type in GSO handlers 2018-01-22 16:01:30 -05:00
tcp_output.c bpf: Add BPF_SOCK_OPS_RETRANS_CB 2018-01-25 16:41:14 -08:00
tcp_rate.c tcp: invalidate rate samples during SACK reneging 2017-12-08 10:07:02 -05:00
tcp_recovery.c tcp: evaluate packet losses upon RTT change 2017-12-08 14:14:11 -05:00
tcp_scalable.c tcp: consolidate congestion control undo functions 2017-08-06 21:25:10 -07:00
tcp_timer.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-01-29 10:15:51 -05:00
tcp_ulp.c net: add a UID to use for ULP socket assignment 2018-02-06 11:39:31 +01:00
tcp_vegas.c tcp: fix under-evaluated ssthresh in TCP Vegas 2017-09-29 06:07:00 +01:00
tcp_vegas.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
tcp_veno.c tcp: consolidate congestion control undo functions 2017-08-06 21:25:10 -07:00
tcp_westwood.c tcp: Revert "tcp: remove CA_ACK_SLOWPATH" 2017-08-30 11:20:08 -07:00
tcp_yeah.c tcp: consolidate congestion control undo functions 2017-08-06 21:25:10 -07:00
tcp.c vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
tunnel4.c
udp_diag.c net: ipv6: add second dif to udp socket lookups 2017-08-07 11:39:22 -07:00
udp_impl.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
udp_offload.c gso: validate gso_type in GSO handlers 2018-01-22 16:01:30 -05:00
udp_tunnel.c net: add infrastructure to un-offload UDP tunnel port 2017-07-24 13:52:59 -07:00
udp.c net: Convert pernet_subsys, registered from inet_init() 2018-02-13 10:36:08 -05:00
udplite.c net: Convert pernet_subsys, registered from inet_init() 2018-02-13 10:36:08 -05:00
xfrm4_input.c xfrm: Reinject transport-mode packets through tasklet 2017-12-19 08:23:21 +01:00
xfrm4_mode_beet.c networking: make skb_pull & friends return void pointers 2017-06-16 11:48:39 -04:00
xfrm4_mode_transport.c xfrm: Add encapsulation header offsets while SKB is not encrypted 2017-04-14 10:07:39 +02:00
xfrm4_mode_tunnel.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-01-24 23:44:15 -05:00
xfrm4_output.c xfrm: Add an IPsec hardware offloading API 2017-04-14 10:06:10 +02:00
xfrm4_policy.c net: Convert pernet_subsys, registered from inet_init() 2018-02-13 10:36:08 -05:00
xfrm4_protocol.c
xfrm4_state.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
xfrm4_tunnel.c