From 2ecb0924d7791372a70ef8f1174e37b329b955c3 Mon Sep 17 00:00:00 2001 From: Allan Stephens Date: Wed, 21 May 2008 14:53:00 -0700 Subject: [PATCH] tipc: Prevent node object duplication due to simultaneous discovery This patch ensures that the simultaneous discovery of the same neighboring node by multiple interfaces does not cause TIPC to add the node into its internal data structures more than once. Signed-off-by: Allan Stephens Signed-off-by: David S. Miller --- net/tipc/node.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) 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; } -- 2.20.1