Commit 3f55211e authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

ipmr: convert mrt_lock to a spinlock 



mrt_lock is only held in write mode, from process context only.

We can switch to a mere spinlock, and avoid blocking BH.

Also, vif_dev_read() is always called under standard rcu_read_lock().

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b96ef16d

net/ipv4/ipmr.c

+9 −10
Original line number Diff line number Diff line
@@ -77,12 +77,11 @@ struct ipmr_result { 
 * Note that the changes are semaphored via rtnl_lock.

 */



static DEFINE_RWLOCK(mrt_lock);

static DEFINE_SPINLOCK(mrt_lock);



static struct net_device *vif_dev_read(const struct vif_device *vif)

{

	return rcu_dereference_check(vif->dev,

				     lockdep_is_held(&mrt_lock));

	return rcu_dereference(vif->dev);

}



/* Multicast router control variables */
@@ -664,7 +663,7 @@ static int vif_delete(struct mr_table *mrt, int vifi, int notify, 
	if (!dev)

		return -EADDRNOTAVAIL;



	write_lock_bh(&mrt_lock);

	spin_lock(&mrt_lock);

	call_ipmr_vif_entry_notifiers(net, FIB_EVENT_VIF_DEL, v, dev,

				      vifi, mrt->id);

	RCU_INIT_POINTER(v->dev, NULL);
@@ -683,7 +682,7 @@ static int vif_delete(struct mr_table *mrt, int vifi, int notify, 
		WRITE_ONCE(mrt->maxvif, tmp + 1);

	}



	write_unlock_bh(&mrt_lock);

	spin_unlock(&mrt_lock);



	dev_set_allmulti(dev, -1);
@@ -785,7 +784,7 @@ static void ipmr_expire_process(struct timer_list *t) 
	spin_unlock(&mfc_unres_lock);

}



/* Fill oifs list. It is called under write locked mrt_lock. */

/* Fill oifs list. It is called under locked mrt_lock. */

static void ipmr_update_thresholds(struct mr_table *mrt, struct mr_mfc *cache,

				   unsigned char *ttls)

{
@@ -897,7 +896,7 @@ static int vif_add(struct net *net, struct mr_table *mrt, 
	v->remote = vifc->vifc_rmt_addr.s_addr;



	/* And finish update writing critical data */

	write_lock_bh(&mrt_lock);

	spin_lock(&mrt_lock);

	rcu_assign_pointer(v->dev, dev);

	netdev_tracker_alloc(dev, &v->dev_tracker, GFP_ATOMIC);

	if (v->flags & VIFF_REGISTER) {
@@ -906,7 +905,7 @@ static int vif_add(struct net *net, struct mr_table *mrt, 
	}

	if (vifi+1 > mrt->maxvif)

		WRITE_ONCE(mrt->maxvif, vifi + 1);

	write_unlock_bh(&mrt_lock);

	spin_unlock(&mrt_lock);

	call_ipmr_vif_entry_notifiers(net, FIB_EVENT_VIF_ADD, v, dev,

				      vifi, mrt->id);

	return 0;
@@ -1211,12 +1210,12 @@ static int ipmr_mfc_add(struct net *net, struct mr_table *mrt, 
				   mfc->mfcc_mcastgrp.s_addr, parent);

	rcu_read_unlock();

	if (c) {

		write_lock_bh(&mrt_lock);

		spin_lock(&mrt_lock);

		c->_c.mfc_parent = mfc->mfcc_parent;

		ipmr_update_thresholds(mrt, &c->_c, mfc->mfcc_ttls);

		if (!mrtsock)

			c->_c.mfc_flags |= MFC_STATIC;

		write_unlock_bh(&mrt_lock);

		spin_unlock(&mrt_lock);

		call_ipmr_mfc_entry_notifiers(net, FIB_EVENT_ENTRY_REPLACE, c,

					      mrt->id);

		mroute_netlink_event(mrt, c, RTM_NEWROUTE);