net: remove dev_base_lock

dev_base_lock is not needed anymore, all remaining users also hold RTNL.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 697370706a82d3501b3586d92ac2a4ab0f18e82f..c541550b0e6e6c8628b4df2b6d47815a8907f2c5 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3077,8 +3077,6 @@ int call_netdevice_notifiers(unsigned long val, struct net_device *dev);
 int call_netdevice_notifiers_info(unsigned long val,
                                  struct netdev_notifier_info *info);
 
-extern rwlock_t                                dev_base_lock;          /* Device list lock */
-
 #define for_each_netdev(net, d)                \
                list_for_each_entry(d, &(net)->dev_base_head, dev_list)
 #define for_each_netdev_reverse(net, d)        \

diff --git a/net/core/dev.c b/net/core/dev.c
index 02cf9fd68da6372194934eabbcec1c6f1ca2ba12..d8dd293a7a279f6495b97ca99b0c1db702e6415d 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -168,28 +168,6 @@ static int call_netdevice_notifiers_extack(unsigned long val,
                                           struct net_device *dev,
                                           struct netlink_ext_ack *extack);
 
-/*
- * The @dev_base_head list is protected by @dev_base_lock and the rtnl
- * semaphore.
- *
- * Pure readers hold dev_base_lock for reading, or rcu_read_lock()
- *
- * Writers must hold the rtnl semaphore while they loop through the
- * dev_base_head list, and hold dev_base_lock for writing when they do the
- * actual updates.  This allows pure readers to access the list even
- * while a writer is preparing to update it.
- *
- * To put it another way, dev_base_lock is held for writing only to
- * protect against pure readers; the rtnl semaphore provides the
- * protection against other writers.
- *
- * See, for example usages, register_netdevice() and
- * unregister_netdevice(), which must be called with the rtnl
- * semaphore held.
- */
-DEFINE_RWLOCK(dev_base_lock);
-EXPORT_SYMBOL(dev_base_lock);
-
 static DEFINE_MUTEX(ifalias_mutex);
 
 /* protects napi_hash addition/deletion and napi_gen_id */
@@ -395,12 +373,10 @@ static void list_netdevice(struct net_device *dev)
 
        ASSERT_RTNL();
 
-       write_lock(&dev_base_lock);
        list_add_tail_rcu(&dev->dev_list, &net->dev_base_head);
        netdev_name_node_add(net, dev->name_node);
        hlist_add_head_rcu(&dev->index_hlist,
                           dev_index_hash(net, dev->ifindex));
-       write_unlock(&dev_base_lock);
 
        netdev_for_each_altname(dev, name_node)
                netdev_name_node_add(net, name_node);
@@ -427,11 +403,9 @@ static void unlist_netdevice(struct net_device *dev)
                netdev_name_node_del(name_node);
 
        /* Unlink dev from the device chain */
-       write_lock(&dev_base_lock);
        list_del_rcu(&dev->dev_list);
        netdev_name_node_del(dev->name_node);
        hlist_del_rcu(&dev->index_hlist);
-       write_unlock(&dev_base_lock);
 
        dev_base_seq_inc(dev_net(dev));
 }
@@ -752,9 +726,9 @@ EXPORT_SYMBOL_GPL(dev_fill_forward_path);
  *     @net: the applicable net namespace
  *     @name: name to find
  *
- *     Find an interface by name. Must be called under RTNL semaphore
- *     or @dev_base_lock. If the name is found a pointer to the device
- *     is returned. If the name is not found then %NULL is returned. The
+ *     Find an interface by name. Must be called under RTNL semaphore.
+ *     If the name is found a pointer to the device is returned.
+ *     If the name is not found then %NULL is returned. The
  *     reference counters are not incremented so the caller must be
  *     careful with locks.
  */
@@ -835,8 +809,7 @@ EXPORT_SYMBOL(netdev_get_by_name);
  *     Search for an interface by index. Returns %NULL if the device
  *     is not found or a pointer to the device. The device has not
  *     had its reference counter increased so the caller must be careful
- *     about locking. The caller must hold either the RTNL semaphore
- *     or @dev_base_lock.
+ *     about locking. The caller must hold the RTNL semaphore.
  */
 
 struct net_device *__dev_get_by_index(struct net *net, int ifindex)
@@ -1241,15 +1214,11 @@ rollback:
 
        netdev_adjacent_rename_links(dev, oldname);
 
-       write_lock(&dev_base_lock);
        netdev_name_node_del(dev->name_node);
-       write_unlock(&dev_base_lock);
 
        synchronize_net();
 
-       write_lock(&dev_base_lock);
        netdev_name_node_add(net, dev->name_node);
-       write_unlock(&dev_base_lock);
 
        ret = call_netdevice_notifiers(NETDEV_CHANGENAME, dev);
        ret = notifier_to_errno(ret);