ipv4: fix multicast losses

[ Upstream commit 9aa3c94ce59066f545521033007abb6441706068 ]

Knut Tidemann found that first packet of a multicast flow was not
correctly received, and bisected the regression to commit b23dd4fe42b4
(Make output route lookup return rtable directly.)

Special thanks to Knut, who provided a very nice bug report, including
sample programs to demonstrate the bug.

Reported-and-bisectedby: Knut Tidemann <knut.andre.tidemann@jotron.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 99e6e4bb1c72d044b97ba93ad6c0bd944d170edd..b8b5c3ff4045346134ece49b729f7cbcc859ce87 100644 (file)
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1914,9 +1914,7 @@ static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
 
        hash = rt_hash(daddr, saddr, dev->ifindex, rt_genid(dev_net(dev)));
        rth = rt_intern_hash(hash, rth, skb, dev->ifindex);
-       err = 0;
-       if (IS_ERR(rth))
-               err = PTR_ERR(rth);
+       return IS_ERR(rth) ? PTR_ERR(rth) : 0;
 
 e_nobufs:
        return -ENOBUFS;