1 files changed, 26 insertions, 0 deletions

diff --git a/net/tipc/node.c b/net/tipc/node.c
index 598f4d3a0098..34e9a2bb7c19 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -52,16 +52,40 @@ static void node_established_contact(struct node *n_ptr);
 
 struct node *tipc_nodes = NULL; /* sorted list of nodes within cluster */
 
+static DEFINE_SPINLOCK(node_create_lock);
+
 u32 tipc_own_tag = 0;
 
+/**
+ * tipc_node_create - create neighboring node
+ *
+ * Currently, this routine is called by neighbor discovery code, which holds
+ * net_lock for reading only.  We must take node_create_lock to ensure a node
+ * isn't created twice if two different bearers discover the node at the same
+ * time.  (It would be preferable to switch to holding net_lock in write mode,
+ * but this is a non-trivial change.)
+ */
+
 struct node *tipc_node_create(u32 addr)
 {
         struct cluster *c_ptr;
         struct node *n_ptr;
         struct node **curr_node;
 
+        spin_lock_bh(&node_create_lock);
+
+        for (n_ptr = tipc_nodes; n_ptr; n_ptr = n_ptr->next) {
+                if (addr < n_ptr->addr)
+                        break;
+                if (addr == n_ptr->addr) {
+                        spin_unlock_bh(&node_create_lock);
+                        return n_ptr;
+                }
+        }
+
         n_ptr = kzalloc(sizeof(*n_ptr),GFP_ATOMIC);
         if (!n_ptr) {
+                spin_unlock_bh(&node_create_lock);
                 warn("Node creation failed, no memory\n");
                 return NULL;
         }
@@ -71,6 +95,7 @@ struct node *tipc_node_create(u32 addr)
                 c_ptr = tipc_cltr_create(addr);
         }
         if (!c_ptr) {
+                spin_unlock_bh(&node_create_lock);
                 kfree(n_ptr);
                 return NULL;
         }
@@ -91,6 +116,7 @@ struct node *tipc_node_create(u32 addr)
                 }
         }
         (*curr_node) = n_ptr;
+        spin_unlock_bh(&node_create_lock);
         return n_ptr;
 }