bpf: Add SO_TXREHASH setsockopt

Add bpf socket option to override rehash behaviour from userspace or from bpf.
Signed-off-by: Akhmat Karakotov <hmukos@yandex-team.ru>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/filter.c

@@ -5091,6 +5091,13 @@ static int _bpf_setsockopt(struct sock *sk, int level, int optname,
 		case SO_REUSEPORT:
 			sk->sk_reuseport = valbool;
 			break;
+		case SO_TXREHASH:
+			if (val < -1 || val > 1) {
+				ret = -EINVAL;
+				break;
+			}
+			sk->sk_txrehash = (u8)val;
+			break;
 		default:
 			ret = -EINVAL;
 		}
@@ -5269,6 +5276,9 @@ static int _bpf_getsockopt(struct sock *sk, int level, int optname,
 		case SO_REUSEPORT:
 			*((int *)optval) = sk->sk_reuseport;
 			break;
+		case SO_TXREHASH:
+			*((int *)optval) = sk->sk_txrehash;
+			break;
 		default:
 			goto err_clear;
 		}