[PATCH net-next 1/1] tipc: fix bug in socket reception function

[PATCH net-next 1/1] tipc: fix bug in socket reception function

[Jon Maloy]

In commit c637c1035534867b85b78b453c38c495b58e2c5a ("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: Jon Maloy <jon.maloy@ericsson.com>
---
 net/tipc/socket.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 6666680..4a98d15 100644
--- a/net/tipc/socket.c
+++ b/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))
-- 
1.9.1

Re: [PATCH net-next 1/1] tipc: fix bug in socket reception function

[David Miller]

From: Jon Maloy <jon.maloy@ericsson.com>
Date: Sun,  8 Feb 2015 11:10:50 -0500

> In commit c637c1035534867b85b78b453c38c495b58e2c5a ("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: Jon Maloy <jon.maloy@ericsson.com>

Applied, thanks Jon.