bonding: fix rx_handler locking

This prevents possible race between bond_enslave and bond_handle_frame
as reported by Nicolas by moving rx_handler register/unregister.
slave->bond is added to hold pointer to master bonding sructure. That
way dev->master is no longer used in bond_handler_frame.
Also, this removes "BUG: scheduling while atomic" message

Reported-by: Nicolas de Pesloüan <nicolas.2p.debian@gmail.com>
Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Signed-off-by: Andy Gospodarek <andy@greyhouse.net>
Tested-by: Nicolas de Pesloüan <nicolas.2p.debian@free.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 32 insertions, 25 deletions

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 338bea147c64..16d6fe954695 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1482,21 +1482,16 @@ static rx_handler_result_t bond_handle_frame(struct sk_buff **pskb)
 {
         struct sk_buff *skb = *pskb;
         struct slave *slave;
-        struct net_device *bond_dev;
         struct bonding *bond;
 
-        slave = bond_slave_get_rcu(skb->dev);
-        bond_dev = ACCESS_ONCE(slave->dev->master);
-        if (unlikely(!bond_dev))
-                return RX_HANDLER_PASS;
-
         skb = skb_share_check(skb, GFP_ATOMIC);
         if (unlikely(!skb))
                 return RX_HANDLER_CONSUMED;
 
         *pskb = skb;
 
-        bond = netdev_priv(bond_dev);
+        slave = bond_slave_get_rcu(skb->dev);
+        bond = slave->bond;
 
         if (bond->params.arp_interval)
                 slave->dev->last_rx = jiffies;
@@ -1505,10 +1500,10 @@ static rx_handler_result_t bond_handle_frame(struct sk_buff **pskb)
                 return RX_HANDLER_EXACT;
         }
 
-        skb->dev = bond_dev;
+        skb->dev = bond->dev;
 
         if (bond->params.mode == BOND_MODE_ALB &&
-            bond_dev->priv_flags & IFF_BRIDGE_PORT &&
+            bond->dev->priv_flags & IFF_BRIDGE_PORT &&
             skb->pkt_type == PACKET_HOST) {
 
                 if (unlikely(skb_cow_head(skb,
@@ -1516,7 +1511,7 @@ static rx_handler_result_t bond_handle_frame(struct sk_buff **pskb)
                         kfree_skb(skb);
                         return RX_HANDLER_CONSUMED;
                 }
-                memcpy(eth_hdr(skb)->h_dest, bond_dev->dev_addr, ETH_ALEN);
+                memcpy(eth_hdr(skb)->h_dest, bond->dev->dev_addr, ETH_ALEN);
         }
 
         return RX_HANDLER_ANOTHER;
@@ -1698,20 +1693,15 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
                 pr_debug("Error %d calling netdev_set_bond_master\n", res);
                 goto err_restore_mac;
         }
-        res = netdev_rx_handler_register(slave_dev, bond_handle_frame,
-                                         new_slave);
-        if (res) {
-                pr_debug("Error %d calling netdev_rx_handler_register\n", res);
-                goto err_unset_master;
-        }
 
         /* open the slave since the application closed it */
         res = dev_open(slave_dev);
         if (res) {
                 pr_debug("Opening slave %s failed\n", slave_dev->name);
-                goto err_unreg_rxhandler;
+                goto err_unset_master;
         }
 
+        new_slave->bond = bond;
         new_slave->dev = slave_dev;
         slave_dev->priv_flags |= IFF_BONDING;
 
@@ -1907,6 +1897,13 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
         if (res)
                 goto err_close;
 
+        res = netdev_rx_handler_register(slave_dev, bond_handle_frame,
+                                         new_slave);
+        if (res) {
+                pr_debug("Error %d calling netdev_rx_handler_register\n", res);
+                goto err_dest_symlinks;
+        }
+
         pr_info("%s: enslaving %s as a%s interface with a%s link.\n",
                 bond_dev->name, slave_dev->name,
                 bond_is_active_slave(new_slave) ? "n active" : " backup",
@@ -1916,13 +1913,12 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
         return 0;
 
 /* Undo stages on error */
+err_dest_symlinks:
+        bond_destroy_slave_symlinks(bond_dev, slave_dev);
+
 err_close:
         dev_close(slave_dev);
 
-err_unreg_rxhandler:
-        netdev_rx_handler_unregister(slave_dev);
-        synchronize_net();
-
 err_unset_master:
         netdev_set_bond_master(slave_dev, NULL);
 
@@ -1988,6 +1984,14 @@ int bond_release(struct net_device *bond_dev, struct net_device *slave_dev)
                 return -EINVAL;
         }
 
+        /* unregister rx_handler early so bond_handle_frame wouldn't be called
+         * for this slave anymore.
+         */
+        netdev_rx_handler_unregister(slave_dev);
+        write_unlock_bh(&bond->lock);
+        synchronize_net();
+        write_lock_bh(&bond->lock);
+
         if (!bond->params.fail_over_mac) {
                 if (!compare_ether_addr(bond_dev->dev_addr, slave->perm_hwaddr) &&
                     bond->slave_cnt > 1)
@@ -2104,8 +2108,6 @@ int bond_release(struct net_device *bond_dev, struct net_device *slave_dev)
                 netif_addr_unlock_bh(bond_dev);
         }
 
-        netdev_rx_handler_unregister(slave_dev);
-        synchronize_net();
         netdev_set_bond_master(slave_dev, NULL);
 
         slave_disable_netpoll(slave);
@@ -2186,6 +2188,12 @@ static int bond_release_all(struct net_device *bond_dev)
                  */
                 write_unlock_bh(&bond->lock);
 
+                /* unregister rx_handler early so bond_handle_frame wouldn't
+                 * be called for this slave anymore.
+                 */
+                netdev_rx_handler_unregister(slave_dev);
+                synchronize_net();
+
                 if (bond_is_lb(bond)) {
                         /* must be called only after the slave
                          * has been detached from the list
@@ -2217,8 +2225,6 @@ static int bond_release_all(struct net_device *bond_dev)
                         netif_addr_unlock_bh(bond_dev);
                 }
 
-                netdev_rx_handler_unregister(slave_dev);
-                synchronize_net();
                 netdev_set_bond_master(slave_dev, NULL);
 
                 slave_disable_netpoll(slave);
diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
index 6b26962fd0ec..90736cb4d975 100644
--- a/drivers/net/bonding/bonding.h
+++ b/drivers/net/bonding/bonding.h
@@ -187,6 +187,7 @@ struct slave {
         struct net_device *dev; /* first - useful for panic debug */
         struct slave *next;
         struct slave *prev;
+        struct bonding *bond; /* our master */
         int    delay;
         unsigned long jiffies;
         unsigned long last_arp_rx;