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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/bcast.c
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/bcast.c')
-rw-r--r--net/tipc/bcast.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/net/tipc/bcast.c b/net/tipc/bcast.c
index 4289dd62f589..ae558dd7f8ee 100644
--- a/net/tipc/bcast.c
+++ b/net/tipc/bcast.c
@@ -329,13 +329,12 @@ static void bclink_peek_nack(struct net *net, struct tipc_msg *msg)
return;
tipc_node_lock(n_ptr);
-
if (n_ptr->bclink.recv_permitted &&
(n_ptr->bclink.last_in != n_ptr->bclink.last_sent) &&
(n_ptr->bclink.last_in == msg_bcgap_after(msg)))
n_ptr->bclink.oos_state = 2;
-
tipc_node_unlock(n_ptr);
+ tipc_node_put(n_ptr);
}
/* tipc_bclink_xmit - deliver buffer chain to all nodes in cluster
@@ -466,6 +465,7 @@ void tipc_bclink_rcv(struct net *net, struct sk_buff *buf)
tipc_node_unlock(node);
bclink_peek_nack(net, msg);
}
+ tipc_node_put(node);
goto exit;
}
@@ -570,6 +570,7 @@ receive:
unlock:
tipc_node_unlock(node);
+ tipc_node_put(node);
exit:
kfree_skb(buf);
}