ipv4: get rid of ip_ra_lock
After commit 1215e51edad1 ("ipv4: fix a deadlock in ip_ra_control")
we always take RTNL lock for ip_ra_control() which is the only place
we update the list ip_ra_chain, so the ip_ra_lock is no longer needed.
As Eric points out, BH does not need to disable either, RCU readers
don't care.
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 1d46d05..ec4fe3d 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -330,7 +330,6 @@
sent to multicast group to reach destination designated router.
*/
struct ip_ra_chain __rcu *ip_ra_chain;
-static DEFINE_SPINLOCK(ip_ra_lock);
static void ip_ra_destroy_rcu(struct rcu_head *head)
@@ -352,21 +351,17 @@
new_ra = on ? kmalloc(sizeof(*new_ra), GFP_KERNEL) : NULL;
- spin_lock_bh(&ip_ra_lock);
for (rap = &ip_ra_chain;
- (ra = rcu_dereference_protected(*rap,
- lockdep_is_held(&ip_ra_lock))) != NULL;
+ (ra = rtnl_dereference(*rap)) != NULL;
rap = &ra->next) {
if (ra->sk == sk) {
if (on) {
- spin_unlock_bh(&ip_ra_lock);
kfree(new_ra);
return -EADDRINUSE;
}
/* dont let ip_call_ra_chain() use sk again */
ra->sk = NULL;
RCU_INIT_POINTER(*rap, ra->next);
- spin_unlock_bh(&ip_ra_lock);
if (ra->destructor)
ra->destructor(sk);
@@ -380,17 +375,14 @@
return 0;
}
}
- if (!new_ra) {
- spin_unlock_bh(&ip_ra_lock);
+ if (!new_ra)
return -ENOBUFS;
- }
new_ra->sk = sk;
new_ra->destructor = destructor;
RCU_INIT_POINTER(new_ra->next, ra);
rcu_assign_pointer(*rap, new_ra);
sock_hold(sk);
- spin_unlock_bh(&ip_ra_lock);
return 0;
}