[PATCH net-next 03/10] eql: use __dev_get_by_name instead of dev_get_by_name to find interface

Ying Xue
2014-01-14T07:42:32Z

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>
---
drivers/net/eql.c | 95 +++++++++++++++++++++++------------------------------
1 file changed, 42 insertions(+), 53 deletions(-)

diff --git a/drivers/net/eql.c b/drivers/net/eql.c
index f219d38..7a79b60 100644
--- 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;
}

--
1.7.9.5