bonding: create bond_first_slave_rcu()

The bond_first_slave_rcu() will be used to instead of bond_first_slave()
in rcu_read_lock().

According to the Jay Vosburgh's suggestion, the struct netdev_adjacent
should hide from users who wanted to use it directly. so I package a
new function to get the first slave of the bond.

Suggested-by: Nikolay Aleksandrov <nikolay@redhat.com>
Suggested-by: Jay Vosburgh <fubar@us.ibm.com>
Suggested-by: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
index 8283cbdec50aa40099b380b5954a5e73308e6b36..8f0d6d0c383b591c5687feb9246b93d1e50af523 100644 (file)
--- a/drivers/net/bonding/bonding.h
+++ b/drivers/net/bonding/bonding.h
@@ -101,6 +101,10 @@
                netdev_adjacent_get_private(bond_slave_list(bond)->prev) : \
                NULL)
 
+/* Caller must have rcu_read_lock */
+#define bond_first_slave_rcu(bond) \
+       netdev_lower_get_first_private_rcu(bond->dev)
+
 #define bond_is_first_slave(bond, pos) (pos == bond_first_slave(bond))
 #define bond_is_last_slave(bond, pos) (pos == bond_last_slave(bond))
 

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 5260d2eae2e6fae44b05bc0ef2f850a2105e3c21..2c74d20dad342fd496bd45873e04a762dc258b68 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2907,6 +2907,7 @@ void *netdev_lower_get_next_private_rcu(struct net_device *dev,
             priv = netdev_lower_get_next_private_rcu(dev, &(iter)))
 
 void *netdev_adjacent_get_private(struct list_head *adj_list);
+void *netdev_lower_get_first_private_rcu(struct net_device *dev);
 struct net_device *netdev_master_upper_dev_get(struct net_device *dev);
 struct net_device *netdev_master_upper_dev_get_rcu(struct net_device *dev);
 int netdev_upper_dev_link(struct net_device *dev, struct net_device *upper_dev);

diff --git a/net/core/dev.c b/net/core/dev.c
index c95d664b2b423e24c22596e29e0d81ef082340b0..9d4369ece6797c1dbdd3157b1f0dafe2c8717bdb 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4543,6 +4543,27 @@ void *netdev_lower_get_next_private_rcu(struct net_device *dev,
 }
 EXPORT_SYMBOL(netdev_lower_get_next_private_rcu);
 
+/**
+ * netdev_lower_get_first_private_rcu - Get the first ->private from the
+ *                                    lower neighbour list, RCU
+ *                                    variant
+ * @dev: device
+ *
+ * Gets the first netdev_adjacent->private from the dev's lower neighbour
+ * list. The caller must hold RCU read lock.
+ */
+void *netdev_lower_get_first_private_rcu(struct net_device *dev)
+{
+       struct netdev_adjacent *lower;
+
+       lower = list_first_or_null_rcu(&dev->adj_list.lower,
+                       struct netdev_adjacent, list);
+       if (lower)
+               return lower->private;
+       return NULL;
+}
+EXPORT_SYMBOL(netdev_lower_get_first_private_rcu);
+
 /**
  * netdev_master_upper_dev_get_rcu - Get master upper device
  * @dev: device