On Friday 19 September 2014, Octavian Purdila wrote:

+struct dln2_gpio_pin {
+	__le16 pin;
+} __packed;

This does not need to be marked packed, since it is never embedded in another
structure.

+struct dln2_gpio_pin_val {
+	__le16 pin;
+	u8 value;
+} __packed;

It's enough here to mark just the 'pin' member as packed.

+static int dln2_gpio_get_pin_count(struct platform_device *pdev)
+{
+	int ret;
+	__le16 count;
+	int len = sizeof(count);
+
+	ret = dln2_transfer(pdev, DLN2_GPIO_GET_PIN_COUNT, NULL, 0, &count,
+			    &len);

You must not do a USB transaction on stack memory.

+static int dln2_gpio_pin_cmd(struct dln2_gpio *dln2, int cmd, unsigned pin)
+{
+	struct dln2_gpio_pin req = {
+		.pin = cpu_to_le16(pin),
+	};
+
+	return dln2_transfer(dln2->pdev, cmd, &req, sizeof(req), NULL, NULL);
+}

Same here

+static int dln2_gpio_pin_val(struct dln2_gpio *dln2, int cmd, unsigned int pin)
+{
+	int ret;
+	struct dln2_gpio_pin req = {
+		.pin = cpu_to_le16(pin),
+	};
+	struct dln2_gpio_pin_val rsp;

And here.

+static int dln2_gpio_set_debounce(struct gpio_chip *chip, unsigned offset,
+				  unsigned debounce)
+{
+	struct dln2_gpio *dln2 = container_of(chip, struct dln2_gpio, gpio);
+	struct {
+		__le32 duration;
+	} __packed req = {
+		.duration = cpu_to_le32(debounce),
+	};
+
+	return dln2_transfer(dln2->pdev, DLN2_GPIO_SET_DEBOUNCE,
+			     &req, sizeof(req), NULL, NULL);
+}

Here you also have a strange __packed attribute that makes no sense
for a local variable, in addition to the stack problem.

I think the only correct way to handle these is to add a dynamic
allocation of an entire page for the DMA, which can probably be
part of the dln2_transfer function so you don't have to do it
in each caller.

	Arnd