android_kernel_oneplus_msm8998/net
Ihar Hrachyshka 009f58797c neighbour: update neigh timestamps iff update is effective
[ Upstream commit 77d7123342dcf6442341b67816321d71da8b2b16 ]

It's a common practice to send gratuitous ARPs after moving an
IP address to another device to speed up healing of a service. To
fulfill service availability constraints, the timing of network peers
updating their caches to point to a new location of an IP address can be
particularly important.

Sometimes neigh_update calls won't touch neither lladdr nor state, for
example if an update arrives in locktime interval. The neigh->updated
value is tested by the protocol specific neigh code, which in turn
will influence whether NEIGH_UPDATE_F_OVERRIDE gets set in the
call to neigh_update() or not. As a result, we may effectively ignore
the update request, bailing out of touching the neigh entry, except that
we still bump its timestamps inside neigh_update.

This may be a problem for updates arriving in quick succession. For
example, consider the following scenario:

A service is moved to another device with its IP address. The new device
sends three gratuitous ARP requests into the network with ~1 seconds
interval between them. Just before the first request arrives to one of
network peer nodes, its neigh entry for the IP address transitions from
STALE to DELAY.  This transition, among other things, updates
neigh->updated. Once the kernel receives the first gratuitous ARP, it
ignores it because its arrival time is inside the locktime interval. The
kernel still bumps neigh->updated. Then the second gratuitous ARP
request arrives, and it's also ignored because it's still in the (new)
locktime interval. Same happens for the third request. The node
eventually heals itself (after delay_first_probe_time seconds since the
initial transition to DELAY state), but it just wasted some time and
require a new ARP request/reply round trip. This unfortunate behaviour
both puts more load on the network, as well as reduces service
availability.

This patch changes neigh_update so that it bumps neigh->updated (as well
as neigh->confirmed) only once we are sure that either lladdr or entry
state will change). In the scenario described above, it means that the
second gratuitous ARP request will actually update the entry lladdr.

Ideally, we would update the neigh entry on the very first gratuitous
ARP request. The locktime mechanism is designed to ignore ARP updates in
a short timeframe after a previous ARP update was honoured by the kernel
layer. This would require tracking timestamps for state transitions
separately from timestamps when actual updates are received. This would
probably involve changes in neighbour struct. Therefore, the patch
doesn't tackle the issue of the first gratuitous APR ignored, leaving
it for a follow-up.

Signed-off-by: Ihar Hrachyshka <ihrachys@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-04-13 19:50:06 +02:00
..
6lowpan 6lowpan: put mcast compression in an own function 2015-10-21 00:49:25 +02:00
9p net/9p: Switch to wait_event_killable() 2017-11-30 08:37:25 +00:00
802 net: Kill dev_rebuild_header 2015-03-02 16:43:41 -05:00
8021q net/8021q: create device with all possible features in wanted_features 2018-03-22 09:23:21 +01:00
appletalk net: Pass kern from net_proto_family.create to sk_alloc 2015-05-11 10:50:17 -04:00
atm atm: deal with setting entry before mkip was called 2015-09-17 22:13:32 -07:00
ax25 ax25: Fix segfault after sock connection timeout 2017-02-04 09:45:09 +01:00
batman-adv batman-adv: handle race condition for claims between gateways 2018-03-22 09:23:21 +01:00
bluetooth Bluetooth: Fix missing encryption refresh on Security Request 2018-04-08 11:51:59 +02:00
bridge netfilter: bridge: ebt_among: add more missing match size checks 2018-04-08 11:51:59 +02:00
caif net: caif: Fix a sleep-in-atomic bug in cfpkt_create_pfx 2017-07-05 14:37:14 +02:00
can can: af_can: canfd_rcv(): replace WARN_ONCE by pr_warn_once 2018-01-31 12:06:08 +01:00
ceph libceph: force GFP_NOIO for socket allocations 2017-04-08 09:53:30 +02:00
core neighbour: update neigh timestamps iff update is effective 2018-04-13 19:50:06 +02:00
dcb net/dcb: make dcbnl.c explicitly non-modular 2015-10-09 07:52:27 -07:00
dccp dccp: check sk for closed state in dccp_sendmsg() 2018-03-31 18:12:33 +02:00
decnet dn_getsockoptdecnet: move nf_{get/set}sockopt outside sock lock 2018-02-25 11:03:38 +01:00
dns_resolver KEYS: Fix race between updating and finding a negative key 2017-10-27 10:23:18 +02:00
dsa net: dsa: select NET_SWITCHDEV 2017-11-15 17:13:11 +01:00
ethernet net: introduce device min_header_len 2017-02-18 16:39:27 +01:00
hsr net/hsr: fix a warning message 2015-11-23 14:56:15 -05:00
ieee802154 ieee802154: 6lowpan: fix possible NULL deref in lowpan_device_event() 2018-03-31 18:12:34 +02:00
ipv4 netfilter: nf_nat_h323: fix logical-not-parentheses warning 2018-04-08 11:51:57 +02:00
ipv6 ipv6: avoid dad-failures for addresses with NODAD 2018-04-13 19:50:06 +02:00
ipx ipx: call ipxitf_put() in ioctl error path 2017-05-25 14:30:13 +02:00
irda irda: do not leak initialized list.dev to userspace 2017-08-30 10:19:21 +02:00
iucv net/iucv: Free memory obtained by kzalloc 2018-03-31 18:12:33 +02:00
key af_key: Fix slab-out-of-bounds in pfkey_compile_policy. 2018-04-13 19:50:01 +02:00
l2tp l2tp: do not accept arbitrary sockets 2018-03-31 18:12:33 +02:00
l3mdev net: Add netif_is_l3_slave 2015-10-07 04:27:43 -07:00
lapb lapb: move EXPORT_SYMBOL after functions. 2014-10-24 15:51:42 -04:00
llc net/llc: avoid BUG_ON() in skb_orphan() 2017-02-26 11:07:49 +01:00
mac80211 mac80211: bail out from prep_connection() if a reconfig is ongoing 2018-04-13 19:50:01 +02:00
mac802154 mac802154: llsec: use kzfree 2015-10-21 00:49:24 +02:00
mpls mpls, nospec: Sanitize array index in mpls_label_ok() 2018-03-11 16:19:47 +01:00
netfilter netfilter: x_tables: add and use xt_check_proc_name 2018-04-08 11:51:59 +02:00
netlabel netlabel: add address family checks to netlbl_{sock,req}_delattr() 2016-08-20 18:09:22 +02:00
netlink netlink: avoid a double skb free in genlmsg_mcast() 2018-03-31 18:12:33 +02:00
netrom netfilter: Remove spurios included of netfilter.h 2015-06-18 21:14:32 +02:00
nfc NFC: fix device-allocation error return 2017-11-30 08:37:23 +00:00
openvswitch openvswitch: Delete conntrack entry clashing with an expectation. 2018-03-24 10:58:43 +01:00
packet net/packet: fix a race in packet_bind() and packet_notifier() 2017-12-16 10:33:56 +01:00
phonet phonet: properly unshare skbs in phonet_rcv() 2016-01-31 11:29:00 -08:00
rds RDS: null pointer dereference in rds_atomic_free_op 2018-01-17 09:35:29 +01:00
rfkill rfkill: fix rfkill_fop_read wait_event usage 2016-03-03 15:07:26 -08:00
rose Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-06-24 02:58:51 -07:00
rxrpc rxrpc: Fix several cases where a padded len isn't checked in ticket decode 2017-06-29 12:48:52 +02:00
sched sched: act_csum: don't mangle TCP and UDP GSO packets 2018-03-22 09:23:22 +01:00
sctp fixup: sctp: verify size of a new chunk in _sctp_make_chunk() 2018-03-18 11:17:54 +01:00
sunrpc SUNRPC: Allow connect to return EHOSTUNREACH 2018-02-03 17:04:28 +01:00
switchdev switchdev: pass pointer to fib_info instead of copy 2016-06-24 10:18:16 -07:00
tipc tipc: fix memory leak in tipc_accept_from_sock() 2017-12-16 10:33:56 +01:00
unix net/unix: don't show information about sockets from other namespaces 2017-11-18 11:11:06 +01:00
vmw_vsock vsock: use new wait API for vsock_stream_sendmsg() 2017-11-30 08:37:19 +00:00
wimax net:wimax: Fix doucble word "the the" in networking.xml 2015-08-09 22:43:52 -07:00
wireless nl80211: Sanitize array index in parse_txq_params 2018-02-25 11:03:53 +01:00
x25 net: fix a kernel infoleak in x25 module 2016-05-18 17:06:43 -07:00
xfrm xfrm: Refuse to insert 32 bit userspace socket policies on 64 bit systems 2018-04-08 11:51:59 +02:00
compat.c audit: log 32-bit socketcalls 2017-10-08 10:14:18 +02:00
Kconfig Make DST_CACHE a silent config option 2018-02-25 11:03:37 +01:00
Makefile net: Introduce L3 Master device abstraction 2015-09-29 20:40:32 -07:00
socket.c bpf: introduce BPF_JIT_ALWAYS_ON config 2018-02-03 17:04:24 +01:00
sysctl_net.c net: Use ns_capable_noaudit() when determining net sysctl permissions 2016-09-15 08:27:50 +02:00