vsock: Refactor vsock_*_getsockopt to resemble sock_getsockopt

In preparation for sharing the implementation of sock_get_timeout.
Signed-off-by: Richard Palethorpe <rpalethorpe@suse.com>
Cc: Richard Palethorpe <rpalethorpe@richiejp.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/vmw_vsock/af_vsock.c

@@ -1648,68 +1648,59 @@ static int vsock_connectible_getsockopt(struct socket *sock,
 					char __user *optval,
 					int __user *optlen)
 {
-	int err;
+	struct sock *sk = sock->sk;
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	union {
+		u64 val64;
+		struct __kernel_old_timeval tm;
+	} v;
+
+	int lv = sizeof(v.val64);
 	int len;
-	struct sock *sk;
-	struct vsock_sock *vsk;
-	u64 val;
 
 	if (level != AF_VSOCK)
 		return -ENOPROTOOPT;
 
-	err = get_user(len, optlen);
-	if (err != 0)
-		return err;
-
-#define COPY_OUT(_v)                            \
-	do {					\
-		if (len < sizeof(_v))		\
-			return -EINVAL;		\
-						\
-		len = sizeof(_v);		\
-		if (copy_to_user(optval, &_v, len) != 0)	\
-			return -EFAULT;				\
-								\
-	} while (0)
+	if (get_user(len, optlen))
+		return -EFAULT;
 
-	err = 0;
-	sk = sock->sk;
-	vsk = vsock_sk(sk);
+	memset(&v, 0, sizeof(v));
 
 	switch (optname) {
 	case SO_VM_SOCKETS_BUFFER_SIZE:
-		val = vsk->buffer_size;
-		COPY_OUT(val);
+		v.val64 = vsk->buffer_size;
 		break;
 
 	case SO_VM_SOCKETS_BUFFER_MAX_SIZE:
-		val = vsk->buffer_max_size;
-		COPY_OUT(val);
+		v.val64 = vsk->buffer_max_size;
 		break;
 
 	case SO_VM_SOCKETS_BUFFER_MIN_SIZE:
-		val = vsk->buffer_min_size;
-		COPY_OUT(val);
+		v.val64 = vsk->buffer_min_size;
 		break;
 
-	case SO_VM_SOCKETS_CONNECT_TIMEOUT: {
-		struct __kernel_old_timeval tv;
-		tv.tv_sec = vsk->connect_timeout / HZ;
-		tv.tv_usec =
+	case SO_VM_SOCKETS_CONNECT_TIMEOUT:
+		lv = sizeof(v.tm);
+		v.tm.tv_sec = vsk->connect_timeout / HZ;
+		v.tm.tv_usec =
 		    (vsk->connect_timeout -
-		     tv.tv_sec * HZ) * (1000000 / HZ);
-		COPY_OUT(tv);
+		     v.tm.tv_sec * HZ) * (1000000 / HZ);
 		break;
-	}
+
 	default:
 		return -ENOPROTOOPT;
 	}
 
-	err = put_user(len, optlen);
-	if (err != 0)
+	if (len < lv)
+		return -EINVAL;
+	if (len > lv)
+		len = lv;
+	if (copy_to_user(optval, &v, len))
 		return -EFAULT;
 
-#undef COPY_OUT
+	if (put_user(len, optlen))
+		return -EFAULT;
 
 	return 0;
 }