kernel/include/net, branch linux-4.17.y

tcp: remove DELAYED ACK events in DCTCP

2018-08-24T11:07:09Z

[ Upstream commit a69258f7aa2623e0930212f09c586fd06674ad79 ] After fixing the way DCTCP tracking delayed ACKs, the delayed-ACK related callbacks are no longer needed Signed-off-by: Yuchung Cheng Signed-off-by: Eric Dumazet Acked-by: Neal Cardwell Acked-by: Lawrence Brakmo Signed-off-by: David S. Miller Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

net/sched: act_tunnel_key: fix NULL dereference when 'goto chain' is used

2018-08-24T11:07:02Z

[ Upstream commit 38230a3e0e0933bbcf5df6fa469ba0667f667568 ] the control action in the common member of struct tcf_tunnel_key must be a valid value, as it can contain the chain index when 'goto chain' is used. Ensure that the control action can be read as x->tcfa_action, when x is a pointer to struct tc_action and x->ops->type is TCA_ACT_TUNNEL_KEY, to prevent the following command: # tc filter add dev $h2 ingress protocol ip pref 1 handle 101 flower \ > $tcflags dst_mac $h2mac action tunnel_key unset goto chain 1 from causing a NULL dereference when a matching packet is received: BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 PGD 80000001097ac067 P4D 80000001097ac067 PUD 103b0a067 PMD 0 Oops: 0000 [#1] SMP PTI CPU: 0 PID: 3491 Comm: mausezahn Tainted: G E 4.18.0-rc2.auguri+ #421 Hardware name: Hewlett-Packard HP Z220 CMT Workstation/1790, BIOS K51 v01.58 02/07/2013 RIP: 0010:tcf_action_exec+0xb8/0x100 Code: 00 00 00 20 74 1d 83 f8 03 75 09 49 83 c4 08 4d 39 ec 75 bc 48 83 c4 10 5b 5d 41 5c 41 5d 41 5e 41 5f c3 49 8b 97 a8 00 00 00 <48> 8b 12 48 89 55 00 48 83 c4 10 5b 5d 41 5c 41 5d 41 5e 41 5f c3 RSP: 0018:ffff95145ea03c40 EFLAGS: 00010246 RAX: 0000000020000001 RBX: ffff9514499e5800 RCX: 0000000000000001 RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000 RBP: ffff95145ea03e60 R08: 0000000000000000 R09: ffff95145ea03c9c R10: ffff95145ea03c78 R11: 0000000000000008 R12: ffff951456a69800 R13: ffff951456a69808 R14: 0000000000000001 R15: ffff95144965ee40 FS: 00007fd67ee11740(0000) GS:ffff95145ea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 00000001038a2006 CR4: 00000000001606f0 Call Trace: fl_classify+0x1ad/0x1c0 [cls_flower] ? __update_load_avg_se.isra.47+0x1ca/0x1d0 ? __update_load_avg_se.isra.47+0x1ca/0x1d0 ? update_load_avg+0x665/0x690 ? update_load_avg+0x665/0x690 ? kmem_cache_alloc+0x38/0x1c0 tcf_classify+0x89/0x140 __netif_receive_skb_core+0x5ea/0xb70 ? enqueue_entity+0xd0/0x270 ? process_backlog+0x97/0x150 process_backlog+0x97/0x150 net_rx_action+0x14b/0x3e0 __do_softirq+0xde/0x2b4 do_softirq_own_stack+0x2a/0x40 do_softirq.part.18+0x49/0x50 __local_bh_enable_ip+0x49/0x50 __dev_queue_xmit+0x4ab/0x8a0 ? wait_woken+0x80/0x80 ? packet_sendmsg+0x38f/0x810 ? __dev_queue_xmit+0x8a0/0x8a0 packet_sendmsg+0x38f/0x810 sock_sendmsg+0x36/0x40 __sys_sendto+0x10e/0x140 ? do_vfs_ioctl+0xa4/0x630 ? syscall_trace_enter+0x1df/0x2e0 ? __audit_syscall_exit+0x22a/0x290 __x64_sys_sendto+0x24/0x30 do_syscall_64+0x5b/0x180 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7fd67e18dc93 Code: 48 8b 0d 18 83 20 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 59 c7 20 00 00 75 13 49 89 ca b8 2c 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 34 c3 48 83 ec 08 e8 2b f7 ff ff 48 89 04 24 RSP: 002b:00007ffe0189b748 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00000000020ca010 RCX: 00007fd67e18dc93 RDX: 0000000000000062 RSI: 00000000020ca322 RDI: 0000000000000003 RBP: 00007ffe0189b780 R08: 00007ffe0189b760 R09: 0000000000000014 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000062 R13: 00000000020ca322 R14: 00007ffe0189b760 R15: 0000000000000003 Modules linked in: act_tunnel_key act_gact cls_flower sch_ingress vrf veth act_csum(E) xt_CHECKSUM iptable_mangle ipt_MASQUERADE iptable_nat nf_nat_ipv4 nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack ipt_REJECT nf_reject_ipv4 tun bridge stp llc ebtable_filter ebtables ip6table_filter ip6_tables iptable_filter intel_rapl snd_hda_codec_hdmi x86_pkg_temp_thermal intel_powerclamp snd_hda_codec_realtek coretemp snd_hda_codec_generic kvm_intel kvm irqbypass snd_hda_intel crct10dif_pclmul crc32_pclmul hp_wmi ghash_clmulni_intel pcbc snd_hda_codec aesni_intel sparse_keymap rfkill snd_hda_core snd_hwdep snd_seq crypto_simd iTCO_wdt gpio_ich iTCO_vendor_support wmi_bmof cryptd mei_wdt glue_helper snd_seq_device snd_pcm pcspkr snd_timer snd i2c_i801 lpc_ich sg soundcore wmi mei_me mei ie31200_edac nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs libcrc32c sd_mod sr_mod cdrom i915 video i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ahci crc32c_intel libahci serio_raw sfc libata mtd drm ixgbe mdio i2c_core e1000e dca CR2: 0000000000000000 ---[ end trace 1ab8b5b5d4639dfc ]--- RIP: 0010:tcf_action_exec+0xb8/0x100 Code: 00 00 00 20 74 1d 83 f8 03 75 09 49 83 c4 08 4d 39 ec 75 bc 48 83 c4 10 5b 5d 41 5c 41 5d 41 5e 41 5f c3 49 8b 97 a8 00 00 00 <48> 8b 12 48 89 55 00 48 83 c4 10 5b 5d 41 5c 41 5d 41 5e 41 5f c3 RSP: 0018:ffff95145ea03c40 EFLAGS: 00010246 RAX: 0000000020000001 RBX: ffff9514499e5800 RCX: 0000000000000001 RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000 RBP: ffff95145ea03e60 R08: 0000000000000000 R09: ffff95145ea03c9c R10: ffff95145ea03c78 R11: 0000000000000008 R12: ffff951456a69800 R13: ffff951456a69808 R14: 0000000000000001 R15: ffff95144965ee40 FS: 00007fd67ee11740(0000) GS:ffff95145ea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 00000001038a2006 CR4: 00000000001606f0 Kernel panic - not syncing: Fatal exception in interrupt Kernel Offset: 0x11400000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) ---[ end Kernel panic - not syncing: Fatal exception in interrupt ]--- Fixes: d0f6dd8a914f ("net/sched: Introduce act_tunnel_key") Signed-off-by: Davide Caratti Signed-off-by: David S. Miller Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

net/sched: act_csum: fix NULL dereference when 'goto chain' is used

2018-08-24T11:07:02Z

[ Upstream commit 11a245e2f7bf25fc21f47e4c9c8491841b128890 ] the control action in the common member of struct tcf_csum must be a valid value, as it can contain the chain index when 'goto chain' is used. Ensure that the control action can be read as x->tcfa_action, when x is a pointer to struct tc_action and x->ops->type is TCA_ACT_CSUM, to prevent the following command: # tc filter add dev $h2 ingress protocol ip pref 1 handle 101 flower \ > $tcflags dst_mac $h2mac action csum ip or tcp or udp or sctp goto chain 1 from triggering a NULL pointer dereference when a matching packet is received. BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 PGD 800000010416b067 P4D 800000010416b067 PUD 1041be067 PMD 0 Oops: 0000 [#1] SMP PTI CPU: 0 PID: 3072 Comm: mausezahn Tainted: G E 4.18.0-rc2.auguri+ #421 Hardware name: Hewlett-Packard HP Z220 CMT Workstation/1790, BIOS K51 v01.58 02/07/2013 RIP: 0010:tcf_action_exec+0xb8/0x100 Code: 00 00 00 20 74 1d 83 f8 03 75 09 49 83 c4 08 4d 39 ec 75 bc 48 83 c4 10 5b 5d 41 5c 41 5d 41 5e 41 5f c3 49 8b 97 a8 00 00 00 <48> 8b 12 48 89 55 00 48 83 c4 10 5b 5d 41 5c 41 5d 41 5e 41 5f c3 RSP: 0018:ffffa020dea03c40 EFLAGS: 00010246 RAX: 0000000020000001 RBX: ffffa020d7ccef00 RCX: 0000000000000054 RDX: 0000000000000000 RSI: ffffa020ca5ae000 RDI: ffffa020d7ccef00 RBP: ffffa020dea03e60 R08: 0000000000000000 R09: ffffa020dea03c9c R10: ffffa020dea03c78 R11: 0000000000000008 R12: ffffa020d3fe4f00 R13: ffffa020d3fe4f08 R14: 0000000000000001 R15: ffffa020d53ca300 FS: 00007f5a46942740(0000) GS:ffffa020dea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 0000000104218002 CR4: 00000000001606f0 Call Trace: fl_classify+0x1ad/0x1c0 [cls_flower] ? arp_rcv+0x121/0x1b0 ? __x2apic_send_IPI_dest+0x40/0x40 ? smp_reschedule_interrupt+0x1c/0xd0 ? reschedule_interrupt+0xf/0x20 ? reschedule_interrupt+0xa/0x20 ? device_is_rmrr_locked+0xe/0x50 ? iommu_should_identity_map+0x49/0xd0 ? __intel_map_single+0x30/0x140 ? e1000e_update_rdt_wa.isra.52+0x22/0xb0 [e1000e] ? e1000_alloc_rx_buffers+0x233/0x250 [e1000e] ? kmem_cache_alloc+0x38/0x1c0 tcf_classify+0x89/0x140 __netif_receive_skb_core+0x5ea/0xb70 ? enqueue_task_fair+0xb6/0x7d0 ? process_backlog+0x97/0x150 process_backlog+0x97/0x150 net_rx_action+0x14b/0x3e0 __do_softirq+0xde/0x2b4 do_softirq_own_stack+0x2a/0x40 do_softirq.part.18+0x49/0x50 __local_bh_enable_ip+0x49/0x50 __dev_queue_xmit+0x4ab/0x8a0 ? wait_woken+0x80/0x80 ? packet_sendmsg+0x38f/0x810 ? __dev_queue_xmit+0x8a0/0x8a0 packet_sendmsg+0x38f/0x810 sock_sendmsg+0x36/0x40 __sys_sendto+0x10e/0x140 ? do_vfs_ioctl+0xa4/0x630 ? syscall_trace_enter+0x1df/0x2e0 ? __audit_syscall_exit+0x22a/0x290 __x64_sys_sendto+0x24/0x30 do_syscall_64+0x5b/0x180 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f5a45cbec93 Code: 48 8b 0d 18 83 20 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 59 c7 20 00 00 75 13 49 89 ca b8 2c 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 34 c3 48 83 ec 08 e8 2b f7 ff ff 48 89 04 24 RSP: 002b:00007ffd0ee6d748 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 0000000001161010 RCX: 00007f5a45cbec93 RDX: 0000000000000062 RSI: 0000000001161322 RDI: 0000000000000003 RBP: 00007ffd0ee6d780 R08: 00007ffd0ee6d760 R09: 0000000000000014 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000062 R13: 0000000001161322 R14: 00007ffd0ee6d760 R15: 0000000000000003 Modules linked in: act_csum act_gact cls_flower sch_ingress vrf veth act_tunnel_key(E) xt_CHECKSUM iptable_mangle ipt_MASQUERADE iptable_nat nf_nat_ipv4 nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack ipt_REJECT nf_reject_ipv4 tun bridge stp llc ebtable_filter ebtables ip6table_filter ip6_tables iptable_filter intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel snd_hda_codec_hdmi snd_hda_codec_realtek kvm snd_hda_codec_generic hp_wmi iTCO_wdt sparse_keymap rfkill mei_wdt iTCO_vendor_support wmi_bmof gpio_ich irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel pcbc aesni_intel snd_hda_intel crypto_simd cryptd snd_hda_codec glue_helper snd_hda_core snd_hwdep snd_seq snd_seq_device snd_pcm pcspkr i2c_i801 snd_timer snd sg lpc_ich soundcore wmi mei_me mei ie31200_edac nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs libcrc32c sr_mod cdrom sd_mod ahci libahci crc32c_intel i915 ixgbe serio_raw libata video dca i2c_algo_bit sfc drm_kms_helper syscopyarea mtd sysfillrect mdio sysimgblt fb_sys_fops drm e1000e i2c_core CR2: 0000000000000000 ---[ end trace 3c9e9d1a77df4026 ]--- RIP: 0010:tcf_action_exec+0xb8/0x100 Code: 00 00 00 20 74 1d 83 f8 03 75 09 49 83 c4 08 4d 39 ec 75 bc 48 83 c4 10 5b 5d 41 5c 41 5d 41 5e 41 5f c3 49 8b 97 a8 00 00 00 <48> 8b 12 48 89 55 00 48 83 c4 10 5b 5d 41 5c 41 5d 41 5e 41 5f c3 RSP: 0018:ffffa020dea03c40 EFLAGS: 00010246 RAX: 0000000020000001 RBX: ffffa020d7ccef00 RCX: 0000000000000054 RDX: 0000000000000000 RSI: ffffa020ca5ae000 RDI: ffffa020d7ccef00 RBP: ffffa020dea03e60 R08: 0000000000000000 R09: ffffa020dea03c9c R10: ffffa020dea03c78 R11: 0000000000000008 R12: ffffa020d3fe4f00 R13: ffffa020d3fe4f08 R14: 0000000000000001 R15: ffffa020d53ca300 FS: 00007f5a46942740(0000) GS:ffffa020dea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 0000000104218002 CR4: 00000000001606f0 Kernel panic - not syncing: Fatal exception in interrupt Kernel Offset: 0x26400000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) ---[ end Kernel panic - not syncing: Fatal exception in interrupt ]--- Fixes: 9c5f69bbd75a ("net/sched: act_csum: don't use spinlock in the fast path") Signed-off-by: Davide Caratti Signed-off-by: David S. Miller Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

ipv6: make ipv6_renew_options() interrupt/kernel safe

2018-08-24T11:07:00Z

[ Upstream commit a9ba23d48dbc6ffd08426bb10f05720e0b9f5c14 ] At present the ipv6_renew_options_kern() function ends up calling into access_ok() which is problematic if done from inside an interrupt as access_ok() calls WARN_ON_IN_IRQ() on some (all?) architectures (x86-64 is affected). Example warning/backtrace is shown below: WARNING: CPU: 1 PID: 3144 at lib/usercopy.c:11 _copy_from_user+0x85/0x90 ... Call Trace: ipv6_renew_option+0xb2/0xf0 ipv6_renew_options+0x26a/0x340 ipv6_renew_options_kern+0x2c/0x40 calipso_req_setattr+0x72/0xe0 netlbl_req_setattr+0x126/0x1b0 selinux_netlbl_inet_conn_request+0x80/0x100 selinux_inet_conn_request+0x6d/0xb0 security_inet_conn_request+0x32/0x50 tcp_conn_request+0x35f/0xe00 ? __lock_acquire+0x250/0x16c0 ? selinux_socket_sock_rcv_skb+0x1ae/0x210 ? tcp_rcv_state_process+0x289/0x106b tcp_rcv_state_process+0x289/0x106b ? tcp_v6_do_rcv+0x1a7/0x3c0 tcp_v6_do_rcv+0x1a7/0x3c0 tcp_v6_rcv+0xc82/0xcf0 ip6_input_finish+0x10d/0x690 ip6_input+0x45/0x1e0 ? ip6_rcv_finish+0x1d0/0x1d0 ipv6_rcv+0x32b/0x880 ? ip6_make_skb+0x1e0/0x1e0 __netif_receive_skb_core+0x6f2/0xdf0 ? process_backlog+0x85/0x250 ? process_backlog+0x85/0x250 ? process_backlog+0xec/0x250 process_backlog+0xec/0x250 net_rx_action+0x153/0x480 __do_softirq+0xd9/0x4f7 do_softirq_own_stack+0x2a/0x40 ... While not present in the backtrace, ipv6_renew_option() ends up calling access_ok() via the following chain: access_ok() _copy_from_user() copy_from_user() ipv6_renew_option() The fix presented in this patch is to perform the userspace copy earlier in the call chain such that it is only called when the option data is actually coming from userspace; that place is do_ipv6_setsockopt(). Not only does this solve the problem seen in the backtrace above, it also allows us to simplify the code quite a bit by removing ipv6_renew_options_kern() completely. We also take this opportunity to cleanup ipv6_renew_options()/ipv6_renew_option() a small amount as well. This patch is heavily based on a rough patch by Al Viro. I've taken his original patch, converted a kmemdup() call in do_ipv6_setsockopt() to a memdup_user() call, made better use of the e_inval jump target in the same function, and cleaned up the use ipv6_renew_option() by ipv6_renew_options(). CC: Al Viro Signed-off-by: Paul Moore Signed-off-by: David S. Miller Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

netfilter: ipv6: nf_defrag: reduce struct net memory waste

2018-08-24T11:06:39Z

[ Upstream commit 9ce7bc036ae4cfe3393232c86e9e1fea2153c237 ] It is a waste of memory to use a full "struct netns_sysctl_ipv6" while only one pointer is really used, considering netns_sysctl_ipv6 keeps growing. Also, since "struct netns_frags" has cache line alignment, it is better to move the frags_hdr pointer outside, otherwise we spend a full cache line for this pointer. This saves 192 bytes of memory per netns. Fixes: c038a767cd69 ("ipv6: add a new namespace for nf_conntrack_reasm") Signed-off-by: Eric Dumazet Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

vsock: split dwork to avoid reinitializations

2018-08-22T05:44:51Z

[ Upstream commit 455f05ecd2b219e9a216050796d30c830d9bc393 ] syzbot reported that we reinitialize an active delayed work in vsock_stream_connect(): ODEBUG: init active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x90 kernel/workqueue.c:1414 WARNING: CPU: 1 PID: 11518 at lib/debugobjects.c:329 debug_print_object+0x16a/0x210 lib/debugobjects.c:326 The pattern is apparently wrong, we should only initialize the dealyed work once and could repeatly schedule it. So we have to move out the initializations to allocation side. And to avoid confusion, we can split the shared dwork into two, instead of re-using the same one. Fixes: d021c344051a ("VSOCK: Introduce VM Sockets") Reported-by: Cc: Andy king Cc: Stefan Hajnoczi Cc: Jorgen Hansen Signed-off-by: Cong Wang Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

llc: use refcount_inc_not_zero() for llc_sap_find()

2018-08-22T05:44:51Z

[ Upstream commit 0dcb82254d65f72333aa50ad626d1e9665ad093b ] llc_sap_put() decreases the refcnt before deleting sap from the global list. Therefore, there is a chance llc_sap_find() could find a sap with zero refcnt in this global list. Close this race condition by checking if refcnt is zero or not in llc_sap_find(), if it is zero then it is being removed so we can just treat it as gone. Reported-by: Signed-off-by: Cong Wang Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

tcp: add max_quickacks param to tcp_incr_quickack and tcp_enter_quickack_mode

2018-08-03T05:48:06Z

[ Upstream commit 9a9c9b51e54618861420093ae6e9b50a961914c5 ] We want to add finer control of the number of ACK packets sent after ECN events. This patch is not changing current behavior, it only enables following change. Signed-off-by: Eric Dumazet Acked-by: Soheil Hassas Yeganeh Acked-by: Neal Cardwell Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

net/ipv6: Fix linklocal to global address with VRF

2018-07-28T05:57:15Z

[ Upstream commit 24b711edfc34bc45777a3f068812b7d1ed004a5d ] Example setup: host: ip -6 addr add dev eth1 2001:db8:104::4 where eth1 is enslaved to a VRF switch: ip -6 ro add 2001:db8:104::4/128 dev br1 where br1 only has an LLA ping6 2001:db8:104::4 ssh 2001:db8:104::4 (NOTE: UDP works fine if the PKTINFO has the address set to the global address and ifindex is set to the index of eth1 with a destination an LLA). For ICMP, icmp6_iif needs to be updated to check if skb->dev is an L3 master. If it is then return the ifindex from rt6i_idev similar to what is done for loopback. For TCP, restore the original tcp_v6_iif definition which is needed in most places and add a new tcp_v6_iif_l3_slave that considers the l3_slave variability. This latter check is only needed for socket lookups. Fixes: 9ff74384600a ("net: vrf: Handle ipv6 multicast and link-local addresses") Signed-off-by: David Ahern Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

tcp: do not delay ACK in DCTCP upon CE status change

2018-07-28T05:57:14Z

[ Upstream commit a0496ef2c23b3b180902dd185d0d63ccbc624cf8 ] Per DCTCP RFC8257 (Section 3.2) the ACK reflecting the CE status change has to be sent immediately so the sender can respond quickly: """ When receiving packets, the CE codepoint MUST be processed as follows: 1. If the CE codepoint is set and DCTCP.CE is false, set DCTCP.CE to true and send an immediate ACK. 2. If the CE codepoint is not set and DCTCP.CE is true, set DCTCP.CE to false and send an immediate ACK. """ Previously DCTCP implementation may continue to delay the ACK. This patch fixes that to implement the RFC by forcing an immediate ACK. Tested with this packetdrill script provided by Larry Brakmo 0.000 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 0.000 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0 0.000 setsockopt(3, SOL_TCP, TCP_CONGESTION, "dctcp", 5) = 0 0.000 bind(3, ..., ...) = 0 0.000 listen(3, 1) = 0 0.100 < [ect0] SEW 0:0(0) win 32792 0.100 > SE. 0:0(0) ack 1 0.110 < [ect0] . 1:1(0) ack 1 win 257 0.200 accept(3, ..., ...) = 4 +0 setsockopt(4, SOL_SOCKET, SO_DEBUG, [1], 4) = 0 0.200 < [ect0] . 1:1001(1000) ack 1 win 257 0.200 > [ect01] . 1:1(0) ack 1001 0.200 write(4, ..., 1) = 1 0.200 > [ect01] P. 1:2(1) ack 1001 0.200 < [ect0] . 1001:2001(1000) ack 2 win 257 +0.005 < [ce] . 2001:3001(1000) ack 2 win 257 +0.000 > [ect01] . 2:2(0) ack 2001 // Previously the ACK below would be delayed by 40ms +0.000 > [ect01] E. 2:2(0) ack 3001 +0.500 < F. 9501:9501(0) ack 4 win 257 Signed-off-by: Yuchung Cheng Acked-by: Neal Cardwell Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman