tipc: fix unsafe rcu locking when accessing publication list

The binding table's 'cluster_scope' list is rcu protected to handle
races between threads changing the list and those traversing the list at
the same moment. We have now found that the function named_distribute()
uses the regular list_for_each() macro to traverse the said list.
Likewise, the function tipc_named_withdraw() is removing items from the
same list using the regular list_del() call. When these two functions
execute in parallel we see occasional crashes.

This commit fixes this by adding the missing _rcu() suffixes.

Signed-off-by: Tung Nguyen <[e-mail]>
Signed-off-by: Jon Maloy <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/tipc/name_distr.c

···
 	struct sk_buff *buf;
 	struct distr_item *item;
 
-	list_del(&publ->binding_node);
+	list_del_rcu(&publ->binding_node);
 
 	if (publ->scope == TIPC_NODE_SCOPE)
 		return NULL;
···
 			ITEM_SIZE) * ITEM_SIZE;
 	u32 msg_rem = msg_dsz;
 
-	list_for_each_entry(publ, pls, binding_node) {
+	list_for_each_entry_rcu(publ, pls, binding_node) {
 		/* Prepare next buffer: */
 		if (!skb) {
 			skb = named_prepare_buf(net, PUBLICATION, msg_rem,