neighbour: restore protocol != 0 check in pneigh update

Prior to commit dc2a27e524ac ("neighbour: Update pneigh_entry in
pneigh_create()."), a pneigh's protocol was updated only when the
value of the NDA_PROTOCOL attribute was non-0. While moving the code,
that check was removed. This is a small change of user-visible
behavior, and inconsistent with the (non-proxy) neighbour behavior.

Fixes: dc2a27e524ac ("neighbour: Update pneigh_entry in pneigh_create().")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/38c61de1bb032871a886aff9b9b52fe1cdd4cada.1772894876.git.sd@queasysnail.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index a95cfe77f7f00ebfc19a1d92ff210ede3f3f42a2..c56a4e7bf790cdde5852d8b25b38166ad1e8999d 100644 (file)
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -820,7 +820,8 @@ int pneigh_create(struct neigh_table *tbl, struct net *net,
 update:
        WRITE_ONCE(n->flags, flags);
        n->permanent = permanent;
-       WRITE_ONCE(n->protocol, protocol);
+       if (protocol)
+               WRITE_ONCE(n->protocol, protocol);
 out:
        mutex_unlock(&tbl->phash_lock);
        return err;