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Commit ba3f571d authored by WANG Cong's avatar WANG Cong Committed by David S. Miller
Browse files

ipv4: get rid of ip_ra_lock 



After commit 1215e51e ("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: default avatarCong Wang <xiyou.wangcong@gmail.com>
Acked-by: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5010e948

net/ipv4/ip_sockglue.c

+2 −10
Original line number Diff line number Diff line
@@ -330,7 +330,6 @@ int ip_cmsg_send(struct sock *sk, struct msghdr *msg, struct ipcm_cookie *ipc, 
   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 @@ int ip_ra_control(struct sock *sk, unsigned char on, 


	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 @@ int ip_ra_control(struct sock *sk, unsigned char on, 
			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;

}