Commit 20fd4d1f authored by Pravin B Shelar's avatar Pravin B Shelar Committed by David S. Miller
Browse files

gre: Simplify gre protocol registration locking. 



Use cmpxchg() for atomic protocol registration which saves
code and data space.

Signed-off-by: default avatarPravin B Shelar <pshelar@nicira.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ac8025a6

net/ipv4/gre.c

+13 −27
Original line number Diff line number Diff line
@@ -26,46 +26,32 @@ 




static const struct gre_protocol __rcu *gre_proto[GREPROTO_MAX] __read_mostly;

static DEFINE_SPINLOCK(gre_proto_lock);



int gre_add_protocol(const struct gre_protocol *proto, u8 version)

{

	if (version >= GREPROTO_MAX)

		goto err_out;



	spin_lock(&gre_proto_lock);

	if (gre_proto[version])

		goto err_out_unlock;



	RCU_INIT_POINTER(gre_proto[version], proto);

	spin_unlock(&gre_proto_lock);

	return 0;

		return -EINVAL;



err_out_unlock:

	spin_unlock(&gre_proto_lock);

err_out:

	return -1;

	return (cmpxchg((const struct gre_protocol **)&gre_proto[version], NULL, proto) == NULL) ?

		0 : -EBUSY;

}

EXPORT_SYMBOL_GPL(gre_add_protocol);



int gre_del_protocol(const struct gre_protocol *proto, u8 version)

{

	int ret;



	if (version >= GREPROTO_MAX)

		goto err_out;



	spin_lock(&gre_proto_lock);

	if (rcu_dereference_protected(gre_proto[version],

			lockdep_is_held(&gre_proto_lock)) != proto)

		goto err_out_unlock;

	RCU_INIT_POINTER(gre_proto[version], NULL);

	spin_unlock(&gre_proto_lock);

		return -EINVAL;



	ret = (cmpxchg((const struct gre_protocol **)&gre_proto[version], proto, NULL) == proto) ?

		0 : -EBUSY;



	if (ret)

		return ret;



	synchronize_rcu();

	return 0;



err_out_unlock:

	spin_unlock(&gre_proto_lock);

err_out:

	return -1;

}

EXPORT_SYMBOL_GPL(gre_del_protocol);