netpoll: disable netpoll when enslave a device

V3: rename NETDEV_ENSLAVE to NETDEV_JOIN

Currently we do nothing when we enslave a net device which is running netconsole.
Neil pointed out that we may get weird results in such case, so let's disable
netpoll on the device being enslaved. I think it is too harsh to prevent
the device being ensalved if it is running netconsole.

By the way, this patch also removes the NETDEV_GOING_DOWN from netconsole
netdev notifier, because netpoll will check if the device is running or not
and we don't handle NETDEV_PRE_UP neither.

This patch is based on net-next-2.6.

Signed-off-by: WANG Cong <amwang@redhat.com>
Cc: Neil Horman <nhorman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 20 insertions, 9 deletions

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 088fd845ffdf..f4960f516c39 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1640,6 +1640,8 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
                 }
         }
 
+        call_netdevice_notifiers(NETDEV_JOIN, slave_dev);
+
         /* If this is the first slave, then we need to set the master's hardware
          * address to be the same as the slave's. */
         if (is_zero_ether_addr(bond->dev->dev_addr))
diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index a83e101440fd..4190786de403 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -621,11 +621,10 @@ static int netconsole_netdev_event(struct notifier_block *this,
         bool stopped = false;
 
         if (!(event == NETDEV_CHANGENAME || event == NETDEV_UNREGISTER ||
-              event == NETDEV_BONDING_DESLAVE || event == NETDEV_GOING_DOWN))
+              event == NETDEV_BONDING_DESLAVE || event == NETDEV_JOIN))
                 goto done;
 
         spin_lock_irqsave(&target_list_lock, flags);
-restart:
         list_for_each_entry(nt, &target_list, list) {
                 netconsole_target_get(nt);
                 if (nt->np.dev == dev) {
@@ -633,6 +632,8 @@ restart:
                         case NETDEV_CHANGENAME:
                                 strlcpy(nt->np.dev_name, dev->name, IFNAMSIZ);
                                 break;
+                        case NETDEV_BONDING_DESLAVE:
+                        case NETDEV_JOIN:
                         case NETDEV_UNREGISTER:
                                 /*
                                  * rtnl_lock already held
@@ -647,11 +648,7 @@ restart:
                                         dev_put(nt->np.dev);
                                         nt->np.dev = NULL;
                                         netconsole_target_put(nt);
-                                        goto restart;
                                 }
-                                /* Fall through */
-                        case NETDEV_GOING_DOWN:
-                        case NETDEV_BONDING_DESLAVE:
                                 nt->enabled = 0;
                                 stopped = true;
                                 break;
@@ -660,10 +657,21 @@ restart:
                 netconsole_target_put(nt);
         }
         spin_unlock_irqrestore(&target_list_lock, flags);
-        if (stopped && (event == NETDEV_UNREGISTER || event == NETDEV_BONDING_DESLAVE))
+        if (stopped) {
                 printk(KERN_INFO "netconsole: network logging stopped on "
-                        "interface %s as it %s\n",  dev->name,
-                        event == NETDEV_UNREGISTER ? "unregistered" : "released slaves");
+                       "interface %s as it ", dev->name);
+                switch (event) {
+                case NETDEV_UNREGISTER:
+                        printk(KERN_CONT "unregistered\n");
+                        break;
+                case NETDEV_BONDING_DESLAVE:
+                        printk(KERN_CONT "released slaves\n");
+                        break;
+                case NETDEV_JOIN:
+                        printk(KERN_CONT "is joining a master device\n");
+                        break;
+                }
+        }
 
 done:
         return NOTIFY_DONE;
diff --git a/include/linux/notifier.h b/include/linux/notifier.h
index 621dfa16acc0..a577762afbe7 100644
--- a/include/linux/notifier.h
+++ b/include/linux/notifier.h
@@ -211,6 +211,7 @@ static inline int notifier_to_errno(int ret)
 #define NETDEV_UNREGISTER_BATCH 0x0011
 #define NETDEV_BONDING_DESLAVE  0x0012
 #define NETDEV_NOTIFY_PEERS     0x0013
+#define NETDEV_JOIN             0x0014
 
 #define SYS_DOWN        0x0001  /* Notify of system down */
 #define SYS_RESTART     SYS_DOWN