ipvs: fix error return code

Initialize return variable before exiting on an error path.

A simplified version of the semantic match that finds this problem is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
(
if@p1 (\(ret < 0\|ret != 0\))
 { ... return ret; }
|
ret@p1 = 0
)
... when != ret = e1
    when != &ret
*if(...)
{
  ... when != ret = e2
      when forall
 return ret;
}

// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Acked-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/ipvs/ip_vs_ctl.c

@@ -1171,8 +1171,10 @@ ip_vs_add_service(struct net *net, struct ip_vs_service_user_kern *u,
 		goto out_err;
 	}
 	svc->stats.cpustats = alloc_percpu(struct ip_vs_cpu_stats);
-	if (!svc->stats.cpustats)
+	if (!svc->stats.cpustats) {
+		ret = -ENOMEM;
 		goto out_err;
+	}
 
 	/* I'm the first user of the service */
 	atomic_set(&svc->usecnt, 0);