Merge branch 'bonding_arp'

Nikolay Aleksandrov says:

====================
bonding: fix arp_validate desync state & race

These two patches aim to fix the possible de-sync state which the bond
can enter if we have arp_validate without arp_interval or the other way
around. They also fix a race condition between arp_validate setting and
mode changing.

Patch 01 - fixes the race condition between store_arp_validate and bond
mode change by using rtnl for sync
Patch 02 - fixes the possible de-sync state by setting/unsetting recv_probe
if arp_interval is set/unset and also if arp_validate is set/unset

v2: Fix the mode check in store_arp_validate
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bonding/bond_main.c

@@ -2404,8 +2404,8 @@ static void bond_validate_arp(struct bonding *bond, struct slave *slave, __be32
 	slave->target_last_arp_rx[i] = jiffies;
 }
 
-static int bond_arp_rcv(const struct sk_buff *skb, struct bonding *bond,
-			struct slave *slave)
+int bond_arp_rcv(const struct sk_buff *skb, struct bonding *bond,
+		 struct slave *slave)
 {
 	struct arphdr *arp = (struct arphdr *)skb->data;
 	unsigned char *arp_ptr;

drivers/net/bonding/bond_sysfs.c

@@ -349,6 +349,8 @@ static ssize_t bonding_store_mode(struct device *d,
 		goto out;
 	}
 
+	/* don't cache arp_validate between modes */
+	bond->params.arp_validate = BOND_ARP_VALIDATE_NONE;
 	bond->params.mode = new_value;
 	bond_set_mode_ops(bond, bond->params.mode);
 	pr_info("%s: setting mode to %s (%d).\n",
@@ -419,27 +421,39 @@ static ssize_t bonding_store_arp_validate(struct device *d,
 					  struct device_attribute *attr,
 					  const char *buf, size_t count)
 {
-	int new_value;
 	struct bonding *bond = to_bond(d);
+	int new_value, ret = count;
 
+	if (!rtnl_trylock())
+		return restart_syscall();
 	new_value = bond_parse_parm(buf, arp_validate_tbl);
 	if (new_value < 0) {
 		pr_err("%s: Ignoring invalid arp_validate value %s\n",
 		       bond->dev->name, buf);
-		return -EINVAL;
+		ret = -EINVAL;
+		goto out;
 	}
-	if (new_value && (bond->params.mode != BOND_MODE_ACTIVEBACKUP)) {
+	if (bond->params.mode != BOND_MODE_ACTIVEBACKUP) {
 		pr_err("%s: arp_validate only supported in active-backup mode.\n",
 		       bond->dev->name);
-		return -EINVAL;
+		ret = -EINVAL;
+		goto out;
 	}
 	pr_info("%s: setting arp_validate to %s (%d).\n",
 		bond->dev->name, arp_validate_tbl[new_value].modename,
 		new_value);
 
+	if (bond->dev->flags & IFF_UP) {
+		if (!new_value)
+			bond->recv_probe = NULL;
+		else if (bond->params.arp_interval)
+			bond->recv_probe = bond_arp_rcv;
+	}
 	bond->params.arp_validate = new_value;
+out:
+	rtnl_unlock();
 
-	return count;
+	return ret;
 }
 
 static DEVICE_ATTR(arp_validate, S_IRUGO | S_IWUSR, bonding_show_arp_validate,
@@ -555,8 +569,8 @@ static ssize_t bonding_store_arp_interval(struct device *d,
 					  struct device_attribute *attr,
 					  const char *buf, size_t count)
 {
-	int new_value, ret = count;
 	struct bonding *bond = to_bond(d);
+	int new_value, ret = count;
 
 	if (!rtnl_trylock())
 		return restart_syscall();
@@ -599,8 +613,13 @@ static ssize_t bonding_store_arp_interval(struct device *d,
 		 * is called.
 		 */
 		if (!new_value) {
+			if (bond->params.arp_validate)
+				bond->recv_probe = NULL;
 			cancel_delayed_work_sync(&bond->arp_work);
 		} else {
+			/* arp_validate can be set only in active-backup mode */
+			if (bond->params.arp_validate)
+				bond->recv_probe = bond_arp_rcv;
 			cancel_delayed_work_sync(&bond->mii_work);
 			queue_delayed_work(bond->wq, &bond->arp_work, 0);
 		}

drivers/net/bonding/bonding.h

@@ -430,6 +430,7 @@ static inline bool slave_can_tx(struct slave *slave)
 
 struct bond_net;
 
+int bond_arp_rcv(const struct sk_buff *skb, struct bonding *bond, struct slave *slave);
 struct vlan_entry *bond_next_vlan(struct bonding *bond, struct vlan_entry *curr);
 int bond_dev_queue_xmit(struct bonding *bond, struct sk_buff *skb, struct net_device *slave_dev);
 void bond_xmit_slave_id(struct bonding *bond, struct sk_buff *skb, int slave_id);