Commit c8243452 authored by Ricardo Ribalda's avatar Ricardo Ribalda Committed by Hans Verkuil
Browse files

media: uvcvideo: Pass allocation size directly to uvc_alloc_urb_buffer 



The uvc_alloc_urb_buffer() function implicitly depended on the
stream->urb_size field, which was set by its caller,
uvc_alloc_urb_buffers(). This implicit data flow makes the code harder
to follow.

More importantly, stream->urb_size was updated within the allocation
loop before the allocation was confirmed to be successful. If the
allocation failed, the stream object would be left with a urb_size that
doesn't correspond to valid, allocated URB buffers.

Refactor uvc_alloc_urb_buffer() to accept the buffer size as an explicit
argument. This makes the function's dependencies clear and improves the
robustness of the error handling path. The stream->urb_size is now set only
after a complete and successful allocation.

This is a pure refactoring and introduces no functional changes.

Signed-off-by: default avatarRicardo Ribalda <ribalda@chromium.org>
Reviewed-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: default avatarItay Chamiel <itay.chamiel@q.ai>
Link: https://patch.msgid.link/20260114-uvc-alloc-urb-v1-2-cedf3fb66711@chromium.org


Signed-off-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: default avatarHans Verkuil <hverkuil+cisco@kernel.org>
parent 40d3ac25

drivers/media/usb/uvc/uvc_video.c

+8 −6
Original line number Diff line number Diff line
@@ -1771,12 +1771,13 @@ static void uvc_free_urb_buffers(struct uvc_streaming *stream) 
}



static bool uvc_alloc_urb_buffer(struct uvc_streaming *stream,

				 struct uvc_urb *uvc_urb, gfp_t gfp_flags)

				 struct uvc_urb *uvc_urb, unsigned int size,

				 gfp_t gfp_flags)

{

	struct usb_device *udev = stream->dev->udev;



	uvc_urb->buffer = usb_alloc_noncoherent(udev, stream->urb_size,

						gfp_flags, &uvc_urb->dma,

	uvc_urb->buffer = usb_alloc_noncoherent(udev, size, gfp_flags,

						&uvc_urb->dma,

						uvc_stream_dir(stream),

						&uvc_urb->sgt);

	return !!uvc_urb->buffer;
@@ -1813,12 +1814,13 @@ static int uvc_alloc_urb_buffers(struct uvc_streaming *stream, 


	/* Retry allocations until one succeed. */

	for (; npackets > 0; npackets /= 2) {

		stream->urb_size = psize * npackets;

		unsigned int urb_size = psize * npackets;



		for (i = 0; i < UVC_URBS; ++i) {

			struct uvc_urb *uvc_urb = &stream->uvc_urb[i];



			if (!uvc_alloc_urb_buffer(stream, uvc_urb, gfp_flags)) {

			if (!uvc_alloc_urb_buffer(stream, uvc_urb, urb_size,

						  gfp_flags)) {

				uvc_free_urb_buffers(stream);

				break;

			}
@@ -1830,6 +1832,7 @@ static int uvc_alloc_urb_buffers(struct uvc_streaming *stream, 
			uvc_dbg(stream->dev, VIDEO,

				"Allocated %u URB buffers of %ux%u bytes each\n",

				UVC_URBS, npackets, psize);

			stream->urb_size = urb_size;

			return npackets;

		}

	}
@@ -1837,7 +1840,6 @@ static int uvc_alloc_urb_buffers(struct uvc_streaming *stream, 
	uvc_dbg(stream->dev, VIDEO,

		"Failed to allocate URB buffers (%u bytes per packet)\n",

		psize);

	stream->urb_size = 0;

	return 0;

}