ipv4 : igmp : fix error handle in ip_mc_add_src()

When add sources to interface failure, need to roll back the sfcount[MODE]
to before state. We need to match it corresponding.

Acked-by: David L Stevens <dlstevens@us.ibm.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Jun Zhao <mypopydev@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index c7472eff2d51..b2ca095cb9da 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -1716,7 +1716,8 @@ static int ip_mc_add_src(struct in_device *in_dev, __be32 *pmca, int sfmode,
         if (err) {
                 int j;
 
-                pmc->sfcount[sfmode]--;
+                if (!delta)
+                        pmc->sfcount[sfmode]--;
                 for (j=0; j<i; j++)
                         (void) ip_mc_del1_src(pmc, sfmode, &psfsrc[j]);
         } else if (isexclude != (pmc->sfcount[MCAST_EXCLUDE] != 0)) {