1 files changed, 50 insertions, 5 deletions

diff --git a/net/tipc/node.c b/net/tipc/node.c
index 598f4d3a0098..ee952ad60218 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;
 }
 
@@ -574,12 +600,14 @@ u32 tipc_available_nodes(const u32 domain)
         struct node *n_ptr;
         u32 cnt = 0;
 
+        read_lock_bh(&tipc_net_lock);
         for (n_ptr = tipc_nodes; n_ptr; n_ptr = n_ptr->next) {
                 if (!in_scope(domain, n_ptr->addr))
                         continue;
                 if (tipc_node_is_up(n_ptr))
                         cnt++;
         }
+        read_unlock_bh(&tipc_net_lock);
         return cnt;
 }
 
@@ -599,19 +627,26 @@ struct sk_buff *tipc_node_get_nodes(const void *req_tlv_area, int req_tlv_space)
                 return tipc_cfg_reply_error_string(TIPC_CFG_INVALID_VALUE
                                                    " (network address)");
 
-        if (!tipc_nodes)
+        read_lock_bh(&tipc_net_lock);
+        if (!tipc_nodes) {
+                read_unlock_bh(&tipc_net_lock);
                 return tipc_cfg_reply_none();
+        }
 
         /* For now, get space for all other nodes
            (will need to modify this when slave nodes are supported */
 
         payload_size = TLV_SPACE(sizeof(node_info)) * (tipc_max_nodes - 1);
-        if (payload_size > 32768u)
+        if (payload_size > 32768u) {
+                read_unlock_bh(&tipc_net_lock);
                 return tipc_cfg_reply_error_string(TIPC_CFG_NOT_SUPPORTED
                                                    " (too many nodes)");
+        }
         buf = tipc_cfg_reply_alloc(payload_size);
-        if (!buf)
+        if (!buf) {
+                read_unlock_bh(&tipc_net_lock);
                 return NULL;
+        }
 
         /* Add TLVs for all nodes in scope */
 
@@ -624,6 +659,7 @@ struct sk_buff *tipc_node_get_nodes(const void *req_tlv_area, int req_tlv_space)
                                     &node_info, sizeof(node_info));
         }
 
+        read_unlock_bh(&tipc_net_lock);
         return buf;
 }
 
@@ -646,16 +682,22 @@ struct sk_buff *tipc_node_get_links(const void *req_tlv_area, int req_tlv_space)
         if (tipc_mode != TIPC_NET_MODE)
                 return tipc_cfg_reply_none();
 
+        read_lock_bh(&tipc_net_lock);
+
         /* Get space for all unicast links + multicast link */
 
         payload_size = TLV_SPACE(sizeof(link_info)) *
                 (tipc_net.zones[tipc_zone(tipc_own_addr)]->links + 1);
-        if (payload_size > 32768u)
+        if (payload_size > 32768u) {
+                read_unlock_bh(&tipc_net_lock);
                 return tipc_cfg_reply_error_string(TIPC_CFG_NOT_SUPPORTED
                                                    " (too many links)");
+        }
         buf = tipc_cfg_reply_alloc(payload_size);
-        if (!buf)
+        if (!buf) {
+                read_unlock_bh(&tipc_net_lock);
                 return NULL;
+        }
 
         /* Add TLV for broadcast link */
 
@@ -671,6 +713,7 @@ struct sk_buff *tipc_node_get_links(const void *req_tlv_area, int req_tlv_space)
 
                 if (!in_scope(domain, n_ptr->addr))
                         continue;
+                tipc_node_lock(n_ptr);
                 for (i = 0; i < MAX_BEARERS; i++) {
                         if (!n_ptr->links[i])
                                 continue;
@@ -680,7 +723,9 @@ struct sk_buff *tipc_node_get_links(const void *req_tlv_area, int req_tlv_space)
                         tipc_cfg_append_tlv(buf, TIPC_TLV_LINK_INFO,
                                             &link_info, sizeof(link_info));
                 }
+                tipc_node_unlock(n_ptr);
         }
 
+        read_unlock_bh(&tipc_net_lock);
         return buf;
 }