tipc: fix bug in socket reception function

In commit c637c103 ("tipc: resolve race
problem at unicast message reception") we introduced a time limit
for how long the function tipc_sk_eneque() would be allowed to execute
its loop. Unfortunately, the test for when this limit is passed was put
in the wrong place, resulting in a lost message when the test is true.

We fix this by moving the test to before we dequeue the next buffer
from the input queue.
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/tipc/socket.c

@@ -1802,12 +1802,11 @@ static int tipc_sk_enqueue(struct sk_buff_head *inputq, struct sock *sk,
 	unsigned long time_limit = jiffies + 2;
 
 	while (skb_queue_len(inputq)) {
+		if (unlikely(time_after_eq(jiffies, time_limit)))
+			return TIPC_OK;
 		skb = tipc_skb_dequeue(inputq, dport);
 		if (unlikely(!skb))
 			return TIPC_OK;
-		/* Return if softirq window exhausted */
-		if (unlikely(time_after_eq(jiffies, time_limit)))
-			return TIPC_OK;
 		if (!sock_owned_by_user(sk)) {
 			err = filter_rcv(sk, &skb);
 			if (likely(!skb))