[Devel] [PATCH 1/8 net-2.6.26] [NETNS]: Make netns refconting debug like a socket one.

[Denis V. Lunev]

Make release_net/hold_net noop for performance-hungry people. This is a debug
staff and should be used in the debug mode only.

Add check for net != NULL in hold/release calls. This will be required
later on.

Signed-off-by: Denis V. Lunev <den at openvz.org>
---
 include/net/net_namespace.h |   44 +++++++++++++++++++++++++++---------------
 net/core/net_namespace.c    |    4 +++
 2 files changed, 30 insertions(+), 16 deletions(-)

diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index e2aee26..269a681 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -21,9 +21,11 @@ struct net_device;
 	atomic_t		count;		/* To decided when the network
 						 *  namespace should be freed.
 						 */
+#ifdef NETNS_REFCNT_DEBUG
 	atomic_t		use_count;	/* To track references we
 						 * destroy on demand
 						 */
+#endif
 	struct list_head	list;		/* list of network namespaces */
 	struct work_struct	work;		/* work struct for freeing */
 
@@ -115,17 +119,6 @@ static inline void put_net(struct net *net)
 		__put_net(net);
 }
 
-static inline struct net *hold_net(struct net *net)
-{
-	atomic_inc(&net->use_count);
-	return net;
-}
-
-static inline void release_net(struct net *net)
-{
-	atomic_dec(&net->use_count);
-}
-
 static inline
 int net_eq(const struct net *net1, const struct net *net2)
 {
@@ -141,27 +134,46 @@ static inline void put_net(struct net *net)
 {
 }
 
+static inline struct net *maybe_get_net(struct net *net)
+{
+	return net;
+}
+
+static inline
+int net_eq(const struct net *net1, const struct net *net2)
+{
+	return 1;
+}
+#endif
+
+
+#ifdef NETNS_REFCNT_DEBUG
 static inline struct net *hold_net(struct net *net)
 {
+	if (net == NULL)
+		return NULL;
+	atomic_inc(&net->use_count);
 	return net;
 }
 
 static inline void release_net(struct net *net)
 {
+	if (net == NULL)
+		return;
+	atomic_dec(&net->use_count);
 }
-
-static inline struct net *maybe_get_net(struct net *net)
+#else
+static inline struct net *hold_net(struct net *net)
 {
 	return net;
 }
 
-static inline
-int net_eq(const struct net *net1, const struct net *net2)
+static inline void release_net(struct net *net)
 {
-	return 1;
 }
 #endif
 
+
 #define for_each_net(VAR)				\
 	list_for_each_entry(VAR, &net_namespace_list, list)
 
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 7b66083..f310ef3 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -30,7 +30,9 @@ static __net_init int setup_net(struct net *net)
 	int error;
 
 	atomic_set(&net->count, 1);
+#ifdef NETNS_REFCNT_DEBUG
 	atomic_set(&net->use_count, 0);
+#endif
 
 	error = 0;
 	list_for_each_entry(ops, &pernet_list, list) {
@@ -70,11 +72,13 @@ static void net_free(struct net *net)
 	if (!net)
 		return;
 
+#ifdef NETNS_REFCNT_DEBUG
 	if (unlikely(atomic_read(&net->use_count) != 0)) {
 		printk(KERN_EMERG "network namespace not free! Usage: %d\n",
 			atomic_read(&net->use_count));
 		return;
 	}
+#endif
 
 	kmem_cache_free(net_cachep, net);
 }
-- 
1.5.3.rc5

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