sock: struct proto hash function may error

In order to support fast reuseport lookups in TCP, the hash function
defined in struct proto must be capable of returning an error code.
This patch changes the function signature of all related hash functions
to return an integer and handles or propagates this return value at
all call sites.

Signed-off-by: Craig Gallek <kraig@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 5c5db66..eade66d 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -370,7 +370,11 @@
 		 */
 		inet->inet_sport = htons(inet->inet_num);
 		/* Add to protocol hash chains. */
-		sk->sk_prot->hash(sk);
+		err = sk->sk_prot->hash(sk);
+		if (err) {
+			sk_common_release(sk);
+			goto out;
+		}
 	}
 
 	if (sk->sk_prot->init) {
@@ -1142,8 +1146,7 @@
 	 * Besides that, it does not check for connection
 	 * uniqueness. Wait for troubles.
 	 */
-	__sk_prot_rehash(sk);
-	return 0;
+	return __sk_prot_rehash(sk);
 }
 
 int inet_sk_rebuild_header(struct sock *sk)