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| author | Ying Xue <ying.xue@windriver.com> | 2015-03-26 18:10:24 +0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-03-29 12:40:28 -0700 |
| commit | 8a0f6ebe8494c5c6ccfe12264385b64c280e3241 (patch) | |
| tree | 2f106a95ffda73b8e8f1596cc95152398cd5379b /net/tipc/link.c | |
| parent | b952b2befb6f6b009e91f087285b9a0a6beb1cc8 (diff) | |
| download | linux-8a0f6ebe8494c5c6ccfe12264385b64c280e3241.tar.gz linux-8a0f6ebe8494c5c6ccfe12264385b64c280e3241.tar.bz2 linux-8a0f6ebe8494c5c6ccfe12264385b64c280e3241.zip | |
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/link.c')
| -rw-r--r-- | net/tipc/link.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/net/tipc/link.c b/net/tipc/link.c index f5e086c5f724..514466efc25c 100644 --- a/net/tipc/link.c +++ b/net/tipc/link.c @@ -854,6 +854,7 @@ int tipc_link_xmit(struct net *net, struct sk_buff_head *list, u32 dnode, if (link) rc = __tipc_link_xmit(net, link, list); tipc_node_unlock(node); + tipc_node_put(node); } if (link) return rc; @@ -1116,8 +1117,8 @@ void tipc_rcv(struct net *net, struct sk_buff *skb, struct tipc_bearer *b_ptr) n_ptr = tipc_node_find(net, msg_prevnode(msg)); if (unlikely(!n_ptr)) goto discard; - tipc_node_lock(n_ptr); + tipc_node_lock(n_ptr); /* Locate unicast link endpoint that should handle message */ l_ptr = n_ptr->links[b_ptr->identity]; if (unlikely(!l_ptr)) @@ -1205,6 +1206,7 @@ void tipc_rcv(struct net *net, struct sk_buff *skb, struct tipc_bearer *b_ptr) skb = NULL; unlock: tipc_node_unlock(n_ptr); + tipc_node_put(n_ptr); discard: if (unlikely(skb)) kfree_skb(skb); @@ -2236,7 +2238,6 @@ int tipc_nl_link_dump(struct sk_buff *skb, struct netlink_callback *cb) msg.seq = cb->nlh->nlmsg_seq; rcu_read_lock(); - if (prev_node) { node = tipc_node_find(net, prev_node); if (!node) { @@ -2249,6 +2250,7 @@ int tipc_nl_link_dump(struct sk_buff *skb, struct netlink_callback *cb) cb->prev_seq = 1; goto out; } + tipc_node_put(node); list_for_each_entry_continue_rcu(node, &tn->node_list, list) { @@ -2256,6 +2258,7 @@ int tipc_nl_link_dump(struct sk_buff *skb, struct netlink_callback *cb) err = __tipc_nl_add_node_links(net, &msg, node, &prev_link); tipc_node_unlock(node); + tipc_node_put(node); if (err) goto out; |