2024-11-12, 15:26:59 +0100, Antonio Quartulli wrote:

On 11/11/2024 16:41, Sabrina Dubroca wrote:

quoted

2024-10-29, 11:47:31 +0100, Antonio Quartulli wrote:

quoted

+void ovpn_peer_hash_vpn_ip(struct ovpn_peer *peer)
+	__must_hold(&peer->ovpn->peers->lock)

Changes to peer->vpn_addrs are not protected by peers->lock, so those
could be getting updated while we're rehashing (and taking peer->lock
in ovpn_nl_peer_modify as I'm suggesting above also wouldn't prevent
that).

/me screams :-D

Sorry :)

Indeed peers->lock is only about protecting the lists, not the content of
the listed objects.

How about acquiring the peers->lock before calling ovpn_nl_peer_modify()?

It seems like it would work. Maybe a bit weird to have conditional
locking (MP mode only), but ok. You already have this lock ordering
(hold peers->lock before taking peer->lock) in
ovpn_peer_keepalive_work_mp, so there should be no deadlock from doing
the same thing in the netlink code.

Then I would also do that in ovpn_peer_float to protect that rehash.

It feels like peers->lock is turning into a duplicate of
ovpn->lock. ovpn->lock used for P2P mode, peers->lock used
equivalently for MP mode. You might consider merging them (but I
wouldn't see it as necessary for merging the series unless there's a
locking issue with the current proposal).

-- 
Sabrina