net: Add more comments
This adds comments to different places to improve
readability.
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 922e8b6..1ab4f92 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -323,6 +323,10 @@ struct pernet_operations {
* have to keep in mind all other pernet_operations and
* to introduce a locking, if they share common resources.
*
+ * The only time they are called with exclusive lock is
+ * from register_pernet_subsys(), unregister_pernet_subsys()
+ * register_pernet_device() and unregister_pernet_device().
+ *
* Exit methods using blocking RCU primitives, such as
* synchronize_rcu(), should be implemented via exit_batch.
* Then, destruction of a group of net requires single
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 9e8ee46..b5796d1 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -43,6 +43,8 @@ static bool init_net_initialized;
/*
* pernet_ops_rwsem: protects: pernet_list, net_generic_ids,
* init_net_initialized and first_device pointer.
+ * This is internal net namespace object. Please, don't use it
+ * outside.
*/
DECLARE_RWSEM(pernet_ops_rwsem);
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 73011a6..2d39497 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -459,7 +459,7 @@ static void rtnl_lock_unregistering_all(void)
*/
void rtnl_link_unregister(struct rtnl_link_ops *ops)
{
- /* Close the race with cleanup_net() */
+ /* Close the race with setup_net() and cleanup_net() */
down_write(&pernet_ops_rwsem);
rtnl_lock_unregistering_all();
__rtnl_link_unregister(ops);
