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media: uvcvideo: Pass allocation size directly to uvc_alloc_urb_buffer

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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: Ricardo Ribalda <ribalda@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Itay Chamiel <itay.chamiel@q.ai>
Link: https://patch.msgid.link/20260114-uvc-alloc-urb-v1-2-cedf3fb66711@chromium.org
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
This commit is contained in:
Ricardo Ribalda 2026-01-14 10:32:14 +00:00 committed by Hans Verkuil
parent 40d3ac25c1
commit c824345288
1 changed files with 8 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
drivers/media/usb/uvc/uvc_video.c
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@ -1771,12 +1771,13 @@ static void uvc_free_urb_buffers(struct uvc_streaming *stream)
} }
static bool uvc_alloc_urb_buffer(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; struct usb_device *udev = stream->dev->udev;
uvc_urb->buffer = usb_alloc_noncoherent(udev, stream->urb_size, uvc_urb->buffer = usb_alloc_noncoherent(udev, size, gfp_flags,
gfp_flags, &uvc_urb->dma, &uvc_urb->dma,
uvc_stream_dir(stream), uvc_stream_dir(stream),
&uvc_urb->sgt); &uvc_urb->sgt);
return !!uvc_urb->buffer; return !!uvc_urb->buffer;
@ -1813,12 +1814,13 @@ static int uvc_alloc_urb_buffers(struct uvc_streaming *stream,
/* Retry allocations until one succeed. */ /* Retry allocations until one succeed. */
for (; npackets > 0; npackets /= 2) { for (; npackets > 0; npackets /= 2) {
stream->urb_size = psize * npackets; unsigned int urb_size = psize * npackets;
for (i = 0; i < UVC_URBS; ++i) { for (i = 0; i < UVC_URBS; ++i) {
struct uvc_urb *uvc_urb = &stream->uvc_urb[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); uvc_free_urb_buffers(stream);
break; break;
} }
@ -1830,6 +1832,7 @@ static int uvc_alloc_urb_buffers(struct uvc_streaming *stream,
uvc_dbg(stream->dev, VIDEO, uvc_dbg(stream->dev, VIDEO,
"Allocated %u URB buffers of %ux%u bytes each\n", "Allocated %u URB buffers of %ux%u bytes each\n",
UVC_URBS, npackets, psize); UVC_URBS, npackets, psize);
stream->urb_size = urb_size;
return npackets; return npackets;
} }
} }
@ -1837,7 +1840,6 @@ static int uvc_alloc_urb_buffers(struct uvc_streaming *stream,
uvc_dbg(stream->dev, VIDEO, uvc_dbg(stream->dev, VIDEO,
"Failed to allocate URB buffers (%u bytes per packet)\n", "Failed to allocate URB buffers (%u bytes per packet)\n",
psize); psize);
stream->urb_size = 0;
return 0; return 0;
} }