Commit 7e4da3fc authored Dec 20, 2016 by Krzysztof Opasiak Committed by Felipe Balbi Jan 02, 2017

usb: gadget: composite: Test get_alt() presence instead of set_alt()



By convention (according to doc) if function does not provide
get_alt() callback composite framework should assume that it has only
altsetting 0 and should respond with error if host tries to set
other one.

After commit dd4dff8b ("USB: composite: Fix bug: should test
set_alt function pointer before use it")
we started checking set_alt() callback instead of get_alt().
This check is useless as we check if set_alt() is set inside
usb_add_function() and fail if it's NULL.

Let's fix this check and move comment about why we check the get
method instead of set a little bit closer to prevent future false
fixes.

Fixes: dd4dff8b ("USB: composite: Fix bug: should test set_alt function pointer before use it")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Krzysztof Opasiak <k.opasiak@samsung.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

parent 51c1685d

drivers/usb/gadget/composite.c

+8 −4

Original line number	Diff line number	Diff line
		@@ -1694,9 +1694,7 @@ composite_setup(struct usb_gadget gadget, const struct usb_ctrlrequest ctrl)
		value = min(w_length, (u16) 1);
		break;

		/* function drivers must handle get/set altsetting; if there's
		* no get() method, we know only altsetting zero works.
		*/
		/* function drivers must handle get/set altsetting */
		case USB_REQ_SET_INTERFACE:
		if (ctrl->bRequestType != USB_RECIP_INTERFACE)
		goto unknown;
		@@ -1705,7 +1703,13 @@ composite_setup(struct usb_gadget gadget, const struct usb_ctrlrequest ctrl)
		f = cdev->config->interface[intf];
		if (!f)
		break;
		if (w_value && !f->set_alt)

		/*
		* If there's no get_alt() method, we know only altsetting zero
		* works. There is no need to check if set_alt() is not NULL
		* as we check this in usb_add_function().
		*/
		if (w_value && !f->get_alt)
		break;
		value = f->set_alt(f, w_index, w_value);
		if (value == USB_GADGET_DELAYED_STATUS) {