eql: use __dev_get_by_name instead of dev_get_by_name to find interface

The following call chain indicates that eql_ioctl(), eql_enslave(),
eql_emancipate(), eql_g_slave_cfg() and eql_s_slave_cfg() are
protected under rtnl_lock. So if we use __dev_get_by_name() instead
of dev_get_by_name() to find interface handlers in them, this would
help us avoid to change interface reference counters.

dev_ioctl()
  rtnl_lock()
    dev_ifsioc()
      eql_ioctl()
        eql_enslave()
	eql_emancipate()
	eql_g_slave_cfg()
	eql_s_slave_cfg()
  rtnl_unlock()

Additionally we also change their return values from -EINVAL to
-ENODEV in case that interfaces are no found.

Signed-off-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/eql.c b/drivers/net/eql.c
index f219d38acf580075f4a9c6b93b54bfdcddbd0865..7a79b60468796a88795af28e655a94acf17f981f 100644 (file)
--- a/drivers/net/eql.c
+++ b/drivers/net/eql.c
@@ -395,6 +395,7 @@ static int __eql_insert_slave(slave_queue_t *queue, slave_t *slave)
                if (duplicate_slave)
                        eql_kill_one_slave(queue, duplicate_slave);
 
+               dev_hold(slave->dev);
                list_add(&slave->list, &queue->all_slaves);
                queue->num_slaves++;
                slave->dev->flags |= IFF_SLAVE;
@@ -413,39 +414,35 @@ static int eql_enslave(struct net_device *master_dev, slaving_request_t __user *
        if (copy_from_user(&srq, srqp, sizeof (slaving_request_t)))
                return -EFAULT;
 
-       slave_dev  = dev_get_by_name(&init_net, srq.slave_name);
-       if (slave_dev) {
-               if ((master_dev->flags & IFF_UP) == IFF_UP) {
-                       /* slave is not a master & not already a slave: */
-                       if (!eql_is_master(slave_dev) &&
-                           !eql_is_slave(slave_dev)) {
-                               slave_t *s = kmalloc(sizeof(*s), GFP_KERNEL);
-                               equalizer_t *eql = netdev_priv(master_dev);
-                               int ret;
-
-                               if (!s) {
-                                       dev_put(slave_dev);
-                                       return -ENOMEM;
-                               }
-
-                               memset(s, 0, sizeof(*s));
-                               s->dev = slave_dev;
-                               s->priority = srq.priority;
-                               s->priority_bps = srq.priority;
-                               s->priority_Bps = srq.priority / 8;
-
-                               spin_lock_bh(&eql->queue.lock);
-                               ret = __eql_insert_slave(&eql->queue, s);
-                               if (ret) {
-                                       dev_put(slave_dev);
-                                       kfree(s);
-                               }
-                               spin_unlock_bh(&eql->queue.lock);
-
-                               return ret;
-                       }
+       slave_dev = __dev_get_by_name(&init_net, srq.slave_name);
+       if (!slave_dev)
+               return -ENODEV;
+
+       if ((master_dev->flags & IFF_UP) == IFF_UP) {
+               /* slave is not a master & not already a slave: */
+               if (!eql_is_master(slave_dev) && !eql_is_slave(slave_dev)) {
+                       slave_t *s = kmalloc(sizeof(*s), GFP_KERNEL);
+                       equalizer_t *eql = netdev_priv(master_dev);
+                       int ret;
+
+                       if (!s)
+                               return -ENOMEM;
+
+                       memset(s, 0, sizeof(*s));
+                       s->dev = slave_dev;
+                       s->priority = srq.priority;
+                       s->priority_bps = srq.priority;
+                       s->priority_Bps = srq.priority / 8;
+
+                       spin_lock_bh(&eql->queue.lock);
+                       ret = __eql_insert_slave(&eql->queue, s);
+                       if (ret)
+                               kfree(s);
+
+                       spin_unlock_bh(&eql->queue.lock);
+
+                       return ret;
                }
-               dev_put(slave_dev);
        }
 
        return -EINVAL;
@@ -461,24 +458,20 @@ static int eql_emancipate(struct net_device *master_dev, slaving_request_t __use
        if (copy_from_user(&srq, srqp, sizeof (slaving_request_t)))
                return -EFAULT;
 
-       slave_dev = dev_get_by_name(&init_net, srq.slave_name);
-       ret = -EINVAL;
-       if (slave_dev) {
-               spin_lock_bh(&eql->queue.lock);
-
-               if (eql_is_slave(slave_dev)) {
-                       slave_t *slave = __eql_find_slave_dev(&eql->queue,
-                                                             slave_dev);
+       slave_dev = __dev_get_by_name(&init_net, srq.slave_name);
+       if (!slave_dev)
+               return -ENODEV;
 
-                       if (slave) {
-                               eql_kill_one_slave(&eql->queue, slave);
-                               ret = 0;
-                       }
+       ret = -EINVAL;
+       spin_lock_bh(&eql->queue.lock);
+       if (eql_is_slave(slave_dev)) {
+               slave_t *slave = __eql_find_slave_dev(&eql->queue, slave_dev);
+               if (slave) {
+                       eql_kill_one_slave(&eql->queue, slave);
+                       ret = 0;
                }
-               dev_put(slave_dev);
-
-               spin_unlock_bh(&eql->queue.lock);
        }
+       spin_unlock_bh(&eql->queue.lock);
 
        return ret;
 }
@@ -494,7 +487,7 @@ static int eql_g_slave_cfg(struct net_device *dev, slave_config_t __user *scp)
        if (copy_from_user(&sc, scp, sizeof (slave_config_t)))
                return -EFAULT;
 
-       slave_dev = dev_get_by_name(&init_net, sc.slave_name);
+       slave_dev = __dev_get_by_name(&init_net, sc.slave_name);
        if (!slave_dev)
                return -ENODEV;
 
@@ -510,8 +503,6 @@ static int eql_g_slave_cfg(struct net_device *dev, slave_config_t __user *scp)
        }
        spin_unlock_bh(&eql->queue.lock);
 
-       dev_put(slave_dev);
-
        if (!ret && copy_to_user(scp, &sc, sizeof (slave_config_t)))
                ret = -EFAULT;
 
@@ -529,7 +520,7 @@ static int eql_s_slave_cfg(struct net_device *dev, slave_config_t __user *scp)
        if (copy_from_user(&sc, scp, sizeof (slave_config_t)))
                return -EFAULT;
 
-       slave_dev = dev_get_by_name(&init_net, sc.slave_name);
+       slave_dev = __dev_get_by_name(&init_net, sc.slave_name);
        if (!slave_dev)
                return -ENODEV;
 
@@ -548,8 +539,6 @@ static int eql_s_slave_cfg(struct net_device *dev, slave_config_t __user *scp)
        }
        spin_unlock_bh(&eql->queue.lock);
 
-       dev_put(slave_dev);
-
        return ret;
 }