Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/linville/wireles...

[linux-2.6-omap-h63xx.git] / net / tipc / node.c

diff --git a/net/tipc/node.c b/net/tipc/node.c
index 598f4d3a0098e4f9b1ba5ae5f166f5166db1e069..34e9a2bb7c19d243b5c623957a899e5c8f987607 100644 (file)
--- 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;
 }