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Commit 76d3e153 authored by Kirill Tkhai's avatar Kirill Tkhai Committed by David S. Miller
Browse files

net: Revert "ipv4: get rid of ip_ra_lock" 



This reverts commit ba3f571d. The commit was made
after 1215e51e "ipv4: fix a deadlock in ip_ra_control",
and killed ip_ra_lock, which became useless after rtnl_lock()
made used to destroy every raw ipv4 socket. This scales
very bad, and next patch in series reverts 1215e51e.
ip_ra_lock will be used again.

Signed-off-by: default avatarKirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f2d254fa

net/ipv4/ip_sockglue.c

+10 −2
Original line number Diff line number Diff line
@@ -334,6 +334,7 @@ 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)
@@ -355,17 +356,21 @@ 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 = rtnl_dereference(*rap)) != NULL;

	     (ra = rcu_dereference_protected(*rap,

			lockdep_is_held(&ip_ra_lock))) != 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);
@@ -379,14 +384,17 @@ int ip_ra_control(struct sock *sk, unsigned char on, 
			return 0;

		}

	}

	if (!new_ra)

	if (!new_ra) {

		spin_unlock_bh(&ip_ra_lock);

		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;

}