linux/include/net
Neal Cardwell 9f950415e4 tcp: fix child sockets to use system default congestion control if not set
Linux 3.17 and earlier are explicitly engineered so that if the app
doesn't specifically request a CC module on a listener before the SYN
arrives, then the child gets the system default CC when the connection
is established. See tcp_init_congestion_control() in 3.17 or earlier,
which says "if no choice made yet assign the current value set as
default". The change ("net: tcp: assign tcp cong_ops when tcp sk is
created") altered these semantics, so that children got their parent
listener's congestion control even if the system default had changed
after the listener was created.

This commit returns to those original semantics from 3.17 and earlier,
since they are the original semantics from 2007 in 4d4d3d1e8 ("[TCP]:
Congestion control initialization."), and some Linux congestion
control workflows depend on that.

In summary, if a listener socket specifically sets TCP_CONGESTION to
"x", or the route locks the CC module to "x", then the child gets
"x". Otherwise the child gets current system default from
net.ipv4.tcp_congestion_control. That's the behavior in 3.17 and
earlier, and this commit restores that.

Fixes: 55d8694fa8 ("net: tcp: assign tcp cong_ops when tcp sk is created")
Cc: Florian Westphal <fw@strlen.de>
Cc: Daniel Borkmann <dborkman@redhat.com>
Cc: Glenn Judd <glenn.judd@morganstanley.com>
Cc: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-31 21:49:14 -07:00
..
9p 9p: switch p9_client_read() to passing struct iov_iter * 2015-04-11 22:28:27 -04:00
bluetooth Bluetooth: Read LE remote features during connection establishment 2015-04-09 08:36:54 +03:00
caif
irda
iucv
netfilter netfilter: nf_tables: mark stateful expressions 2015-04-13 20:12:31 +02:00
netns netns: remove BUG_ONs from net_generic() 2015-04-17 15:21:48 -04:00
nfc nfc: nci: Add comment to explain NCI_HCI_MAX_PIPES 2015-04-06 00:19:05 +02:00
phonet
sctp sctp: Fix mangled IPv4 addresses on a IPv6 listening socket 2015-05-27 14:15:26 -04:00
tc_act
6lowpan.h
act_api.h
addrconf.h
af_ieee802154.h
af_rxrpc.h
af_unix.h
af_vsock.h
ah.h
arp.h
atmclip.h
ax25.h
ax88796.h
bond_3ad.h
bond_alb.h
bond_options.h
bonding.h net/bonding: Make DRV macros private 2015-04-26 22:59:53 -04:00
busy_poll.h
cfg80211-wext.h
cfg80211.h cfg80211: move IE split utilities here from mac80211 2015-04-07 13:56:41 +02:00
cfg802154.h cfg802154: pass name_assign_type to rdev_add_virtual_intf() 2015-04-30 18:48:10 +02:00
checksum.h
cipso_ipv4.h
cls_cgroup.h
codel.h codel: fix maxpacket/mtu confusion 2015-05-03 22:17:40 -04:00
compat.h net: switch importing msghdr from userland to {compat_,}import_iovec() 2015-04-09 00:02:26 -04:00
datalink.h
dcbevent.h
dcbnl.h
dn.h
dn_dev.h
dn_fib.h
dn_neigh.h netfilter: Pass socket pointer down through okfn(). 2015-04-07 15:25:55 -04:00
dn_nsp.h
dn_route.h
dsa.h net: dsa: Add basic framework to support ndo_fdb functions 2015-03-29 13:23:54 -07:00
dsfield.h
dst.h
dst_ops.h
esp.h
ethoc.h
fib_rules.h
firewire.h
flow.h
flow_keys.h
flowcache.h
fou.h
garp.h
gen_stats.h
genetlink.h
geneve.h
gre.h
gro_cells.h
gue.h
icmp.h
ieee80211_radiotap.h
ieee802154_netdev.h
if_inet6.h ipv6: do retries on stable privacy addresses 2015-03-23 22:12:09 -04:00
inet6_connection_sock.h
inet6_hashtables.h
inet_common.h
inet_connection_sock.h tcp: fix child sockets to use system default congestion control if not set 2015-05-31 21:49:14 -07:00
inet_ecn.h
inet_frag.h
inet_hashtables.h
inet_sock.h
inet_timewait_sock.h tcp/dccp: get rid of central timewait timer 2015-04-13 16:40:05 -04:00
inetpeer.h tcp: simplify inetpeer_addr_base use 2015-03-31 13:58:35 -04:00
ip.h netfilter: Pass socket pointer down through okfn(). 2015-04-07 15:25:55 -04:00
ip6_checksum.h
ip6_fib.h
ip6_route.h netfilter: Pass socket pointer down through okfn(). 2015-04-07 15:25:55 -04:00
ip6_tunnel.h udp_tunnel: Pass UDP socket down through udp_tunnel{, 6}_xmit_skb(). 2015-04-07 15:29:08 -04:00
ip_fib.h
ip_tunnels.h ipip,gre,vti,sit: implement ndo_get_iflink 2015-04-02 14:05:00 -04:00
ip_vs.h
ipcomp.h
ipconfig.h
ipv6.h net: remove extra newlines 2015-04-07 22:24:37 -04:00
ipx.h
iw_handler.h
lapb.h
lib80211.h
llc.h
llc_c_ac.h
llc_c_ev.h
llc_c_st.h
llc_conn.h
llc_if.h
llc_pdu.h
llc_s_ac.h
llc_s_ev.h
llc_s_st.h
llc_sap.h
mac80211.h mac80211: Fix mac80211.h docbook comments 2015-05-28 14:37:43 +02:00
mac802154.h mac802154: add description to mac802154 APIs 2015-04-30 18:48:09 +02:00
mip6.h
mld.h
mpls.h
mrp.h
ndisc.h
neighbour.h
net_namespace.h
net_ratelimit.h
netevent.h
netlabel.h
netlink.h netlink: implement nla_get_in_addr and nla_get_in6_addr 2015-03-31 13:58:35 -04:00
netprio_cgroup.h
netrom.h
nexthop.h
nl802154.h
p8022.h
ping.h
pkt_cls.h
pkt_sched.h
protocol.h
psnap.h
raw.h
rawv6.h
red.h
regulatory.h
request_sock.h inet: fix possible panic in reqsk_queue_unlink() 2015-04-24 11:39:15 -04:00
rose.h
route.h
rtnetlink.h rtnetlink: Mark name argument of rtnl_create_link() const 2015-04-10 12:42:40 -07:00
sch_generic.h
scm.h
secure_seq.h
slhc_vj.h
snmp.h
sock.h Merge branch 'iocb' into for-davem 2015-04-09 00:01:38 -04:00
Space.h
stp.h
switchdev.h
tcp.h tcp: prepare CC get_info() access from getsockopt() 2015-04-29 17:10:38 -04:00
tcp_memcontrol.h
tcp_states.h
timewait_sock.h
transp_v6.h
tso.h
udp.h
udp_tunnel.h udp_tunnel: Pass UDP socket down through udp_tunnel{, 6}_xmit_skb(). 2015-04-07 15:29:08 -04:00
udplite.h
vsock_addr.h
vxlan.h udp_tunnel: Pass UDP socket down through udp_tunnel{, 6}_xmit_skb(). 2015-04-07 15:29:08 -04:00
wext.h
wimax.h
x25.h
x25device.h
xfrm.h netfilter: Pass socket pointer down through okfn(). 2015-04-07 15:25:55 -04:00