tipc: resolve race problem at unicast message reception

[deliverable/linux.git] / net / tipc / msg.h

diff --git a/net/tipc/msg.h b/net/tipc/msg.h
index 60702992933dde75e58de079310e8d4bd4390da2..ab467261bd9daedd5e2f66462cd99705f131f1e2 100644 (file)
--- a/net/tipc/msg.h
+++ b/net/tipc/msg.h
@@ -45,6 +45,7 @@
  * Note: Some items are also used with TIPC internal message headers
  */
 #define TIPC_VERSION              2
+struct plist;
 
 /*
  * Payload message users are defined in TIPC's public API:
@@ -759,10 +760,82 @@ int tipc_buf_append(struct sk_buff **headbuf, struct sk_buff **buf);
 bool tipc_msg_bundle(struct sk_buff_head *list, struct sk_buff *skb, u32 mtu);
 bool tipc_msg_make_bundle(struct sk_buff_head *list,
                          struct sk_buff *skb, u32 mtu, u32 dnode);
+bool tipc_msg_extract(struct sk_buff *skb, struct sk_buff **iskb, int *pos);
 int tipc_msg_build(struct tipc_msg *mhdr, struct msghdr *m,
                   int offset, int dsz, int mtu, struct sk_buff_head *list);
 bool tipc_msg_lookup_dest(struct net *net, struct sk_buff *skb, u32 *dnode,
                          int *err);
 struct sk_buff *tipc_msg_reassemble(struct sk_buff_head *list);
 
+/* tipc_skb_peek_port(): find a destination port, ignoring all destinations
+ *                       up to and including 'filter'.
+ * Note: ignoring previously tried destinations minimizes the risk of
+ *       contention on the socket lock
+ * @list: list to be peeked in
+ * @filter: last destination to be ignored from search
+ * Returns a destination port number, of applicable.
+ */
+static inline u32 tipc_skb_peek_port(struct sk_buff_head *list, u32 filter)
+{
+       struct sk_buff *skb;
+       u32 dport = 0;
+       bool ignore = true;
+
+       spin_lock_bh(&list->lock);
+       skb_queue_walk(list, skb) {
+               dport = msg_destport(buf_msg(skb));
+               if (!filter || skb_queue_is_last(list, skb))
+                       break;
+               if (dport == filter)
+                       ignore = false;
+               else if (!ignore)
+                       break;
+       }
+       spin_unlock_bh(&list->lock);
+       return dport;
+}
+
+/* tipc_skb_dequeue(): unlink first buffer with dest 'dport' from list
+ * @list: list to be unlinked from
+ * @dport: selection criteria for buffer to unlink
+ */
+static inline struct sk_buff *tipc_skb_dequeue(struct sk_buff_head *list,
+                                              u32 dport)
+{
+       struct sk_buff *_skb, *tmp, *skb = NULL;
+
+       spin_lock_bh(&list->lock);
+       skb_queue_walk_safe(list, _skb, tmp) {
+               if (msg_destport(buf_msg(_skb)) == dport) {
+                       __skb_unlink(_skb, list);
+                       skb = _skb;
+                       break;
+               }
+       }
+       spin_unlock_bh(&list->lock);
+       return skb;
+}
+
+/* tipc_skb_queue_tail(): add buffer to tail of list;
+ * @list: list to be appended to
+ * @skb: buffer to append. Always appended
+ * @dport: the destination port of the buffer
+ * returns true if dport differs from previous destination
+ */
+static inline bool tipc_skb_queue_tail(struct sk_buff_head *list,
+                                      struct sk_buff *skb, u32 dport)
+{
+       struct sk_buff *_skb = NULL;
+       bool rv = false;
+
+       spin_lock_bh(&list->lock);
+       _skb = skb_peek_tail(list);
+       if (!_skb || (msg_destport(buf_msg(_skb)) != dport) ||
+           (skb_queue_len(list) > 32))
+               rv = true;
+       __skb_queue_tail(list, skb);
+       spin_unlock_bh(&list->lock);
+       return rv;
+}
+
 #endif