[patch] (3/8) Add 802.3ad support to bonding

[Shmulik Hen <hshmulik@xxxxxxxxx>]

This patch fixes a hang when enslaving a new slave while incoming traffic 
is running, that looks like a deadlock between the BR_NETPROTO_LOCK,
dev->xmit_lock and the bond lock (happens on quad processor machines,
but KDB back trace wasn't clear enough).

This patch is against bonding 2.4.20-20030317.

diff -Nuarp linux-2.4.20-bonding-20030317/drivers/net/bonding.c 
linux-2.4.20-bonding-20030317-devel/drivers/net/bonding.c
--- linux-2.4.20-bonding-20030317/drivers/net/bonding.c 2003-03-18 
17:03:25.000000000 +0200
+++ linux-2.4.20-bonding-20030317-devel/drivers/net/bonding.c   2003-03-18 
17:03:26.000000000 +0200
@@ -295,6 +295,10 @@
  *     - Fixed hang in bond_release() while traffic is running.                
  *       netdev_set_master() must not be called from within the bond lock.
  *
+ * 2003/03/18 - Tsippy Mendelson <tsippy.mendelson at intel dot com> and
+ *             Shmulik Hen <shmulik.hen at intel dot com>
+ *     - Fixed hang in bond_enslave(): netdev_set_master() must not be
+ *       called from within the bond lock while traffic is running.
  */
 
 #include <linux/config.h>
@@ -1066,14 +1070,12 @@ static int bond_enslave(struct net_devic
                        "Warning : no link monitoring support for %s\n",
                        slave_dev->name);
        }
-       write_lock_irqsave(&bond->lock, flags);
 
        /* not running. */
        if ((slave_dev->flags & IFF_UP) != IFF_UP) {
 #ifdef BONDING_DEBUG
                printk(KERN_CRIT "Error, slave_dev is not running\n");
 #endif
-               write_unlock_irqrestore(&bond->lock, flags);
                return -EINVAL;
        }
 
@@ -1082,12 +1084,10 @@ static int bond_enslave(struct net_devic
 #ifdef BONDING_DEBUG
                printk(KERN_CRIT "Error, Device was already enslaved\n");
 #endif
-               write_unlock_irqrestore(&bond->lock, flags);
                return -EBUSY;
        }
                   
        if ((new_slave = kmalloc(sizeof(slave_t), GFP_ATOMIC)) == NULL) {
-               write_unlock_irqrestore(&bond->lock, flags);
                return -ENOMEM;
        }
        memset(new_slave, 0, sizeof(slave_t));
@@ -1100,9 +1100,7 @@ static int bond_enslave(struct net_devic
 #ifdef BONDING_DEBUG
                printk(KERN_CRIT "Error %d calling netdev_set_master\n", err);
 #endif
-               kfree(new_slave);
-               write_unlock_irqrestore(&bond->lock, flags);
-               return err;      
+               goto err_free;
        }
 
        new_slave->dev = slave_dev;
@@ -1121,6 +1119,8 @@ static int bond_enslave(struct net_devic
                        dev_mc_add (slave_dev, dmi->dmi_addr, dmi->dmi_addrlen, 
0);
        }
 
+       write_lock_irqsave(&bond->lock, flags);
+       
        bond_attach_slave(bond, new_slave);
        new_slave->delay = 0;
        new_slave->link_failure_count = 0;
@@ -1259,7 +1259,11 @@ static int bond_enslave(struct net_devic
                new_slave->state == BOND_STATE_ACTIVE ? "n active" : " backup",
                new_slave->link == BOND_LINK_UP ? "n up" : " down");
 
+       //enslave is successfull
        return 0;
+err_free:
+       kfree(new_slave);
+       return err;
 }
 
 /* 
@@ -1607,6 +1611,9 @@ static int bond_release_all(struct net_d
 
                kfree(our_slave);
 
+               /* Can be safely called from inside the bond lock
+                  since traffic and timers have already stopped
+               */
                netdev_set_master(slave_dev, NULL);
 
                /* only restore its RUNNING flag if monitoring set it down */

-- 
| Shmulik Hen                                    |
| Israel Design Center (Jerusalem)               |
| LAN Access Division                            |
| Intel Communications Group, Intel corp.        |
|                                                |
| Anti-Spam: shmulik dot hen at intel dot com    |