[PATCH 3.16 180/328] igmp: fix incorrect unsolicit report count when join group

[Ben Hutchings]

3.16.62-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Hangbin Liu <liuhangbin@xxxxxxxxx>

commit 4fb7253e4f9a8f06a986a3b317e2f79d9b43d552 upstream.

We should not start timer if im->unsolicit_count equal to 0 after decrease.
Or we will send one more unsolicit report message. i.e. 3 instead of 2 by
default.

Fixes: 1da177e4c3f41 ("Linux-2.6.12-rc2")
Signed-off-by: Hangbin Liu <liuhangbin@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 net/ipv4/igmp.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -795,10 +795,9 @@ static void igmp_timer_expire(unsigned l
 	spin_lock(&im->lock);
 	im->tm_running = 0;
 
-	if (im->unsolicit_count) {
-		im->unsolicit_count--;
+	if (im->unsolicit_count && --im->unsolicit_count)
 		igmp_start_timer(im, unsolicited_report_interval(in_dev));
-	}
+
 	im->reporter = 1;
 	spin_unlock(&im->lock);