[IPV4]: Change ip_defrag to return an integer

Now that ip_frag always returns the packet given to it on input, we can
change it to return an integer indicating error instead.  This patch does
that and updates all its callers accordingly.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index d7fa2bf..32108cf 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -739,7 +739,7 @@
 }
 
 /* Process an incoming IP datagram fragment. */
-struct sk_buff *ip_defrag(struct sk_buff *skb, u32 user)
+int ip_defrag(struct sk_buff *skb, u32 user)
 {
 	struct ipq *qp;
 
@@ -759,12 +759,12 @@
 
 		spin_unlock(&qp->lock);
 		ipq_put(qp, NULL);
-		return ret ? NULL : skb;
+		return ret;
 	}
 
 	IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
 	kfree_skb(skb);
-	return NULL;
+	return -ENOMEM;
 }
 
 void __init ipfrag_init(void)