Commit 79525889 authored by Petr Machata's avatar Petr Machata Committed by Jakub Kicinski
Browse files

net: core: neighbour: Reorder netlink & internal notification 



The netlink message needs to be send inside the critical section where the
neighbor is changed, so that it reflects the notified-upon neighbor state.
On the other hand, there is no such need in case of notifier chain: the
listeners do not assume lock, and often in fact just schedule a delayed
work to act on the neighbor later. At least one in fact also takes the
neighbor lock.

This requires that the netlink notification be done before the internal
notifier chain message is sent. That is safe to do, because the current
listeners, as well as __neigh_notify(), only read the updated neighbor
fields, and never modify them. (Apart from locking.)

Signed-off-by: default avatarPetr Machata <petrm@nvidia.com>
Reviewed-by: default avatarIdo Schimmel <idosch@nvidia.com>
Reviewed-by: default avatarSimon Horman <horms@kernel.org>
Link: https://patch.msgid.link/f3ef74d5460f14c4d102b8a5857d4a6624da9a5a.1769012464.git.petrm@nvidia.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent a228a7e6

net/core/neighbour.c

+2 −2
Original line number Diff line number Diff line
@@ -1187,8 +1187,8 @@ static void neigh_timer_handler(struct timer_list *t) 
	}



	if (notify) {

		call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, neigh);

		neigh_notify(neigh, RTM_NEWNEIGH, 0, 0);

		call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, neigh);

	}



	trace_neigh_timer_handler(neigh, 0);
@@ -1523,8 +1523,8 @@ static int __neigh_update(struct neighbour *neigh, const u8 *lladdr, 
		neigh_update_managed_list(neigh);



	if (notify) {

		call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, neigh);

		neigh_notify(neigh, RTM_NEWNEIGH, 0, nlmsg_pid);

		call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, neigh);

	}



	trace_neigh_update_done(neigh, err);