Commit c486640a authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

ipv6: remove one read_lock()/read_unlock() pair in rt6_check_neigh() 



rt6_check_neigh() uses read_lock() to protect n->nud_state reading.

This seems overkill and causes false sharing.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarDavid Ahern <dsahern@kernel.org>
Reviewed-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent b071af52

net/ipv6/route.c

+4 −4
Original line number Diff line number Diff line
@@ -687,16 +687,16 @@ static enum rt6_nud_state rt6_check_neigh(const struct fib6_nh *fib6_nh) 
	neigh = __ipv6_neigh_lookup_noref(fib6_nh->fib_nh_dev,

					  &fib6_nh->fib_nh_gw6);

	if (neigh) {

		read_lock(&neigh->lock);

		if (neigh->nud_state & NUD_VALID)

		u8 nud_state = READ_ONCE(neigh->nud_state);



		if (nud_state & NUD_VALID)

			ret = RT6_NUD_SUCCEED;

#ifdef CONFIG_IPV6_ROUTER_PREF

		else if (!(neigh->nud_state & NUD_FAILED))

		else if (!(nud_state & NUD_FAILED))

			ret = RT6_NUD_SUCCEED;

		else

			ret = RT6_NUD_FAIL_PROBE;

#endif

		read_unlock(&neigh->lock);

	} else {

		ret = IS_ENABLED(CONFIG_IPV6_ROUTER_PREF) ?

		      RT6_NUD_SUCCEED : RT6_NUD_FAIL_DO_RR;