bonding: fix locking in sysfs primary/active selection
Jay Vosburgh [Fri, 18 Jan 2008 00:24:57 +0000 (16:24 -0800)]
Fix the functions that store the primary and active slave
options via sysfs to hold the correct locks in the correct order.

The bond_change_active_slave and bond_select_active_slave
functions both require rtnl, bond->lock for read and curr_slave_lock for
write_bh, and no other locks.  This is so that the lower level
mode-specific functions (notably for balance-alb mode) can release locks
down to just rtnl in order to call, e.g., dev_set_mac_address with the
locks it expects (rtnl only).

Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>
Signed-off-by: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/net/bonding/bond_sysfs.c

index 11b76b3..28a2d80 100644 (file)
@@ -1075,7 +1075,10 @@ static ssize_t bonding_store_primary(struct device *d,
        struct slave *slave;
        struct bonding *bond = to_bond(d);
 
-       write_lock_bh(&bond->lock);
+       rtnl_lock();
+       read_lock(&bond->lock);
+       write_lock_bh(&bond->curr_slave_lock);
+
        if (!USES_PRIMARY(bond->params.mode)) {
                printk(KERN_INFO DRV_NAME
                       ": %s: Unable to set primary slave; %s is in mode %d\n",
@@ -1109,8 +1112,8 @@ static ssize_t bonding_store_primary(struct device *d,
                }
        }
 out:
-       write_unlock_bh(&bond->lock);
-
+       write_unlock_bh(&bond->curr_slave_lock);
+       read_unlock(&bond->lock);
        rtnl_unlock();
 
        return count;
@@ -1190,7 +1193,8 @@ static ssize_t bonding_store_active_slave(struct device *d,
        struct bonding *bond = to_bond(d);
 
        rtnl_lock();
-       write_lock_bh(&bond->lock);
+       read_lock(&bond->lock);
+       write_lock_bh(&bond->curr_slave_lock);
 
        if (!USES_PRIMARY(bond->params.mode)) {
                printk(KERN_INFO DRV_NAME
@@ -1247,7 +1251,8 @@ static ssize_t bonding_store_active_slave(struct device *d,
                }
        }
 out:
-       write_unlock_bh(&bond->lock);
+       write_unlock_bh(&bond->curr_slave_lock);
+       read_unlock(&bond->lock);
        rtnl_unlock();
 
        return count;