tipc: Prevent node object duplication due to simultaneous discovery (2ecb0924) · Commits · 戴 / test

net/tipc/node.c

+26 −0

Original line number	Diff line number	Diff line
		@@ -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;
		}