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authorYing Xue <ying.xue@windriver.com>2015-03-26 18:10:24 +0800
committerDavid S. Miller <davem@davemloft.net>2015-03-29 12:40:28 -0700
commit8a0f6ebe8494c5c6ccfe12264385b64c280e3241 (patch)
tree2f106a95ffda73b8e8f1596cc95152398cd5379b /net/tipc/node.h
parentb952b2befb6f6b009e91f087285b9a0a6beb1cc8 (diff)
downloadlinux-8a0f6ebe8494c5c6ccfe12264385b64c280e3241.tar.bz2
tipc: involve reference counter for node structure
TIPC node hash node table is protected with rcu lock on read side. tipc_node_find() is used to look for a node object with node address through iterating the hash node table. As the entire process of what tipc_node_find() traverses the table is guarded with rcu read lock, it's safe for us. However, when callers use the node object returned by tipc_node_find(), there is no rcu read lock applied. Therefore, this is absolutely unsafe for callers of tipc_node_find(). Now we introduce a reference counter for node structure. Before tipc_node_find() returns node object to its caller, it first increases the reference counter. Accordingly, after its caller used it up, it decreases the counter again. This can prevent a node being used by one thread from being freed by another thread. Reviewed-by: Erik Hugne <erik.hugne@ericsson.com> Reviewed-by: Jon Maloy <jon.maloy@ericson.com> Signed-off-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/tipc/node.h')
-rw-r--r--net/tipc/node.h9
1 files changed, 7 insertions, 2 deletions
diff --git a/net/tipc/node.h b/net/tipc/node.h
index 9629ecd2bdd8..02d5c20dc551 100644
--- a/net/tipc/node.h
+++ b/net/tipc/node.h
@@ -94,6 +94,7 @@ struct tipc_node_bclink {
/**
* struct tipc_node - TIPC node structure
* @addr: network address of node
+ * @ref: reference counter to node object
* @lock: spinlock governing access to structure
* @net: the applicable net namespace
* @hash: links to adjacent nodes in unsorted hash chain
@@ -115,6 +116,7 @@ struct tipc_node_bclink {
*/
struct tipc_node {
u32 addr;
+ struct kref kref;
spinlock_t lock;
struct net *net;
struct hlist_node hash;
@@ -137,6 +139,7 @@ struct tipc_node {
};
struct tipc_node *tipc_node_find(struct net *net, u32 addr);
+void tipc_node_put(struct tipc_node *node);
struct tipc_node *tipc_node_create(struct net *net, u32 addr);
void tipc_node_stop(struct net *net);
void tipc_node_attach_link(struct tipc_node *n_ptr, struct tipc_link *l_ptr);
@@ -171,10 +174,12 @@ static inline uint tipc_node_get_mtu(struct net *net, u32 addr, u32 selector)
node = tipc_node_find(net, addr);
- if (likely(node))
+ if (likely(node)) {
mtu = node->act_mtus[selector & 1];
- else
+ tipc_node_put(node);
+ } else {
mtu = MAX_MSG_SIZE;
+ }
return mtu;
}