[media] cinergyT2-core: don't do DMA on stack

The USB control messages require DMA to work. We cannot pass
a stack-allocated buffer, as it is not warranted that the
stack would be into a DMA enabled area.
Reviewed-by: Patrick Boettcher <patrick.boettcher@posteo.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/usb/dvb-usb/cinergyT2-core.c

@@ -41,6 +41,8 @@ DVB_DEFINE_MOD_OPT_ADAPTER_NR(adapter_nr);
 
 struct cinergyt2_state {
 	u8 rc_counter;
+	unsigned char data[64];
+	struct mutex data_mutex;
 };
 
 /* We are missing a release hook with usb_device data */
@@ -50,33 +52,52 @@ static struct dvb_usb_device_properties cinergyt2_properties;
 
 static int cinergyt2_streaming_ctrl(struct dvb_usb_adapter *adap, int enable)
 {
-	char buf[] = { CINERGYT2_EP1_CONTROL_STREAM_TRANSFER, enable ? 1 : 0 };
-	char result[64];
-	return dvb_usb_generic_rw(adap->dev, buf, sizeof(buf), result,
-				sizeof(result), 0);
+	struct dvb_usb_device *d = adap->dev;
+	struct cinergyt2_state *st = d->priv;
+	int ret;
+
+	mutex_lock(&st->data_mutex);
+	st->data[0] = CINERGYT2_EP1_CONTROL_STREAM_TRANSFER;
+	st->data[1] = enable ? 1 : 0;
+
+	ret = dvb_usb_generic_rw(d, st->data, 2, st->data, 64, 0);
+	mutex_unlock(&st->data_mutex);
+
+	return ret;
 }
 
 static int cinergyt2_power_ctrl(struct dvb_usb_device *d, int enable)
 {
-	char buf[] = { CINERGYT2_EP1_SLEEP_MODE, enable ? 0 : 1 };
-	char state[3];
-	return dvb_usb_generic_rw(d, buf, sizeof(buf), state, sizeof(state), 0);
+	struct cinergyt2_state *st = d->priv;
+	int ret;
+
+	mutex_lock(&st->data_mutex);
+	st->data[0] = CINERGYT2_EP1_SLEEP_MODE;
+	st->data[1] = enable ? 0 : 1;
+
+	ret = dvb_usb_generic_rw(d, st->data, 2, st->data, 3, 0);
+	mutex_unlock(&st->data_mutex);
+
+	return ret;
 }
 
 static int cinergyt2_frontend_attach(struct dvb_usb_adapter *adap)
 {
-	char query[] = { CINERGYT2_EP1_GET_FIRMWARE_VERSION };
-	char state[3];
+	struct dvb_usb_device *d = adap->dev;
+	struct cinergyt2_state *st = d->priv;
 	int ret;
 
 	adap->fe_adap[0].fe = cinergyt2_fe_attach(adap->dev);
 
-	ret = dvb_usb_generic_rw(adap->dev, query, sizeof(query), state,
-				sizeof(state), 0);
+	mutex_lock(&st->data_mutex);
+	st->data[0] = CINERGYT2_EP1_GET_FIRMWARE_VERSION;
+
+	ret = dvb_usb_generic_rw(d, st->data, 1, st->data, 3, 0);
 	if (ret < 0) {
 		deb_rc("cinergyt2_power_ctrl() Failed to retrieve sleep "
 			"state info\n");
 	}
+	mutex_unlock(&st->data_mutex);
 
 	/* Copy this pointer as we are gonna need it in the release phase */
 	cinergyt2_usb_device = adap->dev;
@@ -141,13 +162,16 @@ static int repeatable_keys[] = {
 static int cinergyt2_rc_query(struct dvb_usb_device *d, u32 *event, int *state)
 {
 	struct cinergyt2_state *st = d->priv;
-	u8 key[5] = {0, 0, 0, 0, 0}, cmd = CINERGYT2_EP1_GET_RC_EVENTS;
 	int i;
 
 	*state = REMOTE_NO_KEY_PRESSED;
 
-	dvb_usb_generic_rw(d, &cmd, 1, key, sizeof(key), 0);
-	if (key[4] == 0xff) {
+	mutex_lock(&st->data_mutex);
+	st->data[0] = CINERGYT2_EP1_GET_RC_EVENTS;
+
+	dvb_usb_generic_rw(d, st->data, 1, st->data, 5, 0);
+
+	if (st->data[4] == 0xff) {
 		/* key repeat */
 		st->rc_counter++;
 		if (st->rc_counter > RC_REPEAT_DELAY) {
@@ -157,31 +181,45 @@ static int cinergyt2_rc_query(struct dvb_usb_device *d, u32 *event, int *state)
 					*event = d->last_event;
 					deb_rc("repeat key, event %x\n",
 						   *event);
-					return 0;
+					goto ret;
 				}
 			}
 			deb_rc("repeated key (non repeatable)\n");
 		}
-		return 0;
+		goto ret;
 	}
 
 	/* hack to pass checksum on the custom field */
-	key[2] = ~key[1];
-	dvb_usb_nec_rc_key_to_event(d, key, event, state);
-	if (key[0] != 0) {
+	st->data[2] = ~st->data[1];
+	dvb_usb_nec_rc_key_to_event(d, st->data, event, state);
+	if (st->data[0] != 0) {
 		if (*event != d->last_event)
 			st->rc_counter = 0;
 
-		deb_rc("key: %*ph\n", 5, key);
+		deb_rc("key: %*ph\n", 5, st->data);
 	}
-	return 0;
+
+ret:
+	mutex_unlock(&st->data_mutex);
+	return ret;
 }
 
 static int cinergyt2_usb_probe(struct usb_interface *intf,
 				const struct usb_device_id *id)
 {
-	return dvb_usb_device_init(intf, &cinergyt2_properties,
-					THIS_MODULE, NULL, adapter_nr);
+	struct dvb_usb_device *d;
+	struct cinergyt2_state *st;
+	int ret;
+
+	ret = dvb_usb_device_init(intf, &cinergyt2_properties,
+				  THIS_MODULE, &d, adapter_nr);
+	if (ret < 0)
+		return ret;
+
+	st = d->priv;
+	mutex_init(&st->data_mutex);
+
+	return 0;
 }