Revert "tipc: Return the correct errno code"

This reverts commit 0efea3c6 because of:
- The returning -ENOBUF error is fine on socket buffer allocation.
- There is side effect in the calling path
tipc_node_xmit()->tipc_link_xmit() when checking error code returning.

Fixes: 0efea3c6 ("tipc: Return the correct errno code")
Acked-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: Hoang Le <hoang.h.le@dektech.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tipc/link.c

@@ -913,7 +913,7 @@ static int link_schedule_user(struct tipc_link *l, struct tipc_msg *hdr)
 	skb = tipc_msg_create(SOCK_WAKEUP, 0, INT_H_SIZE, 0,
 			      dnode, l->addr, dport, 0, 0);
 	if (!skb)
-		return -ENOMEM;
+		return -ENOBUFS;
 	msg_set_dest_droppable(buf_msg(skb), true);
 	TIPC_SKB_CB(skb)->chain_imp = msg_importance(hdr);
 	skb_queue_tail(&l->wakeupq, skb);
@@ -1031,7 +1031,7 @@ void tipc_link_reset(struct tipc_link *l)
  *
  * Consumes the buffer chain.
  * Messages at TIPC_SYSTEM_IMPORTANCE are always accepted
- * Return: 0 if success, or errno: -ELINKCONG, -EMSGSIZE or -ENOBUFS or -ENOMEM
+ * Return: 0 if success, or errno: -ELINKCONG, -EMSGSIZE or -ENOBUFS
  */
 int tipc_link_xmit(struct tipc_link *l, struct sk_buff_head *list,
 		   struct sk_buff_head *xmitq)
@@ -1089,7 +1089,7 @@ int tipc_link_xmit(struct tipc_link *l, struct sk_buff_head *list,
 			if (!_skb) {
 				kfree_skb(skb);
 				__skb_queue_purge(list);
-				return -ENOMEM;
+				return -ENOBUFS;
 			}
 			__skb_queue_tail(transmq, skb);
 			tipc_link_set_skb_retransmit_time(skb, l);