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Yuchung Cheng fd2123a3d7 tcp: avoid resetting ACK timer upon receiving packet with ECN CWR flag 
Previously commit 9aee40006190 ("tcp: ack immediately when a cwr
packet arrives") calls tcp_enter_quickack_mode to force sending
two immediate ACKs upon receiving a packet w/ CWR flag. The side
effect is it'll also reset the delayed ACK timer and interactive
session tracking. This patch removes that side effect by using the
new ACK_NOW flag to force an immmediate ACK.

Packetdrill to demonstrate:

    0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
   +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
   +0 setsockopt(3, SOL_TCP, TCP_CONGESTION, "dctcp", 5) = 0
   +0 bind(3, ..., ...) = 0
   +0 listen(3, 1) = 0

   +0 < [ect0] SEW 0:0(0) win 32792 <mss 1000,sackOK,nop,nop,nop,wscale 7>
   +0 > SE. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
  +.1 < [ect0] . 1:1(0) ack 1 win 257
   +0 accept(3, ..., ...) = 4

   +0 < [ect0] . 1:1001(1000) ack 1 win 257
   +0 > [ect01] . 1:1(0) ack 1001

   +0 write(4, ..., 1) = 1
   +0 > [ect01] P. 1:2(1) ack 1001

   +0 < [ect0] . 1001:2001(1000) ack 2 win 257
   +0 write(4, ..., 1) = 1
   +0 > [ect01] P. 2:3(1) ack 2001

   +0 < [ect0] . 2001:3001(1000) ack 3 win 257
   +0 < [ect0] . 3001:4001(1000) ack 3 win 257
   // Ack delayed ...

   +.01 < [ce] P. 4001:4501(500) ack 3 win 257
   +0 > [ect01] . 3:3(0) ack 4001
   +0 > [ect01] E. 3:3(0) ack 4501

+.001 read(4, ..., 4500) = 4500
   +0 write(4, ..., 1) = 1
   +0 > [ect01] PE. 3:4(1) ack 4501 win 100

 +.01 < [ect0] W. 4501:5501(1000) ack 4 win 257
   // No delayed ACK on CWR flag
   +0 > [ect01] . 4:4(0) ack 5501

 +.31 < [ect0] . 5501:6501(1000) ack 4 win 257
   +0 > [ect01] . 4:4(0) ack 6501

Fixes: 9aee40006190 ("tcp: ack immediately when a cwr packet arrives")
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-08-11 11:31:35 -07:00
..
6lowpan
6lowpan: iphc: reset mac_header after decompress to fix panic
2018-07-06 12:32:12 +02:00
9p
net:mod: remove unneeded variable 'ret' in init_p9
2018-08-08 09:40:44 -07:00
802
…
8021q
net: remove blank lines at end of file
2018-07-24 14:10:43 -07:00
appletalk
Revert changes to convert to ->poll_mask() and aio IOCB_CMD_POLL
2018-06-28 10:40:47 -07:00
atm
net: simplify sock_poll_wait
2018-07-30 09:10:25 -07:00
ax25
ax25: remove blank line at EOF
2018-07-24 14:10:42 -07:00
batman-adv
Merge ra.kernel.org:/pub/scm/linux/kernel/git/torvalds/linux
2018-07-20 21:17:12 -07:00
bluetooth
Bluetooth: Add definitions for LE set address resolution
2018-08-10 16:57:57 +02:00
bpf
bpf/test_run: support cgroup local storage
2018-08-03 00:47:32 +02:00
bpfilter
bpfilter: remove trailing newline
2018-07-24 14:10:42 -07:00
bridge
net/bridge/br_multicast: remove redundant variable "err"
2018-08-06 10:33:44 -07:00
caif
net: simplify sock_poll_wait
2018-07-30 09:10:25 -07:00
can
Revert changes to convert to ->poll_mask() and aio IOCB_CMD_POLL
2018-06-28 10:40:47 -07:00
ceph
The main piece is a set of libceph changes that revamps how OSD
2018-06-15 07:24:58 +09:00
core
net: allow to call netif_reset_xps_queues() under cpus_read_lock
2018-08-09 14:25:06 -07:00
dcb
net: dcb: Add priority-to-DSCP map getters
2018-07-27 13:17:50 -07:00
dccp
Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net
2018-08-09 11:52:36 -07:00
decnet
decnet: fix using plain integer as NULL warning
2018-08-09 14:11:24 -07:00
dns_resolver
net: remove blank lines at end of file
2018-07-24 14:10:43 -07:00
dsa
Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net
2018-08-09 11:52:36 -07:00
ethernet
net: Convert GRO SKB handling to list_head.
2018-06-26 11:33:04 +09:00
hsr
…
ieee802154
net: ieee802154: 6lowpan: remove redundant pointers 'fq' and 'net'
2018-08-06 11:21:15 +02:00
ife
net: sched: ife: check on metadata length
2018-04-22 21:12:00 -04:00
ipv4
tcp: avoid resetting ACK timer upon receiving packet with ECN CWR flag
2018-08-11 11:31:35 -07:00
ipv6
net: ipv6_gre: Fix GRO to work on IPv6 over GRE tap
2018-08-09 14:07:38 -07:00
iucv
net:af_iucv: get rid of the unneeded variable 'err' in afiucv_pm_freeze
2018-08-08 09:39:36 -07:00
kcm
net: remove blank lines at end of file
2018-07-24 14:10:43 -07:00
key
Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next
2018-07-27 09:33:37 -07:00
l2tp
Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net
2018-08-05 13:04:31 -07:00
l3mdev
…
lapb
…
llc
Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net
2018-08-09 11:52:36 -07:00
mac80211
Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net
2018-07-24 19:21:58 -07:00
mac802154
net: mac802154: tx: expand tailroom if necessary
2018-08-06 11:21:37 +02:00
mpls
mpls: remove trailing whitepace
2018-07-24 14:10:42 -07:00
ncsi
net/ncsi: Use netdev_dbg for debug messages
2018-06-20 07:26:58 +09:00
netfilter
netfilter: nfnetlink_osf: fix using plain integer as NULL warning
2018-08-08 19:05:39 +02:00
netlabel
audit: use inline function to get audit context
2018-05-14 17:24:18 -04:00
netlink
Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net
2018-08-05 13:04:31 -07:00
netrom
Revert changes to convert to ->poll_mask() and aio IOCB_CMD_POLL
2018-06-28 10:40:47 -07:00
nfc
net: simplify sock_poll_wait
2018-07-30 09:10:25 -07:00
nsh
nsh: set mac len based on inner packet
2018-07-12 16:55:29 -07:00
openvswitch
Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net
2018-08-02 10:55:32 -07:00
packet
Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net
2018-08-09 11:52:36 -07:00
phonet
Revert changes to convert to ->poll_mask() and aio IOCB_CMD_POLL
2018-06-28 10:40:47 -07:00
psample
…
qrtr
net: qrtr: Reset the node and port ID of broadcast messages
2018-07-05 20:20:03 +09:00
rds
RDS: IB: fix 'passing zero to ERR_PTR()' warning
2018-08-07 13:19:45 -07:00
rfkill
rfkill: Create rfkill-none LED trigger
2018-05-23 11:26:45 +02:00
rose
Revert changes to convert to ->poll_mask() and aio IOCB_CMD_POLL
2018-06-28 10:40:47 -07:00
rxrpc
rxrpc: remove redundant static int 'zero'
2018-08-11 11:25:18 -07:00
sched
net: sched: fix block->refcnt decrement
2018-08-09 14:12:04 -07:00
sctp
sctp: whitespace fixes
2018-07-24 14:10:42 -07:00
smc
net/smc: send response to test link signal
2018-08-10 14:38:43 -07:00
strparser
strparser: remove redundant variable 'rd_desc'
2018-08-01 10:00:06 -07:00
sunrpc
net: Remove some unneeded semicolon
2018-08-04 13:05:39 -07:00
switchdev
…
tipc
Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net
2018-08-09 11:52:36 -07:00
tls
net/tls: Mark the end in scatterlist table
2018-08-05 17:13:58 -07:00
unix
af_unix: ensure POLLOUT on remote close() for connected dgram socket
2018-08-03 16:44:19 -07:00
vmw_vsock
vsock: split dwork to avoid reinitializations
2018-08-07 12:39:13 -07:00
wimax
wimax: remove blank lines at EOF
2018-07-24 14:10:42 -07:00
wireless
Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net
2018-07-24 19:21:58 -07:00
x25
x25: remove blank lines at EOF
2018-07-24 14:10:42 -07:00
xdp
Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net
2018-08-05 13:04:31 -07:00
xfrm
Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net
2018-08-02 10:55:32 -07:00
compat.c
net: avoid unnecessary sock_flag() check when enable timestamp
2018-08-06 10:42:48 -07:00
Kconfig
net: remove blank lines at end of file
2018-07-24 14:10:43 -07:00
Makefile
bpfilter: check compiler capability in Kconfig
2018-06-28 13:36:39 +09:00
socket.c
Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net
2018-08-02 10:55:32 -07:00
sysctl_net.c
net: Drop pernet_operations::async
2018-03-27 13:18:09 -04:00