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Subject[PATCH v4] media: uvcvideo: Remove void casting for the status endpoint
Make the code more resiliant, by replacing the castings with proper
structure definitions and using offsetof() instead of open coding the
location of the data.

Suggested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
media: uvcvideo: Code cleanup for dev->status

Lets remove all the castings and open coding of offsets for it.

To: Yunke Cao <yunkec@chromium.org>
To: Sergey Senozhatsky <senozhatsky@chromium.org>
To: Max Staudt <mstaudt@chromium.org>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: linux-media@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
Changes in v4:
- Fix sizeof() error.
- Keep kzalloc(). Thanks Alan, Christoph and Jonathan
- Reducing the cc: to:
- Link to v3: https://lore.kernel.org/r/20221214-uvc-status-alloc-v3-0-9a67616cc549@chromium.org

Changes in v3:
- Split the patch in two
- Add linux-usb, Alan and Christoph for the allocation change.
- Link to v2: https://lore.kernel.org/r/20221214-uvc-status-alloc-v2-0-3f1cba6fc734@chromium.org

Changes in v2:
- using __aligned(), to keep the old alignment
- Adding Johnathan Cameron to:, as he has some similar experience with iio
- Adding Ming Lei, as this patch kind of revert his patch.
- Link to v1: https://lore.kernel.org/r/20221214-uvc-status-alloc-v1-0-a0098ddc7c93@chromium.org
---
drivers/media/usb/uvc/uvc_status.c | 66 +++++++++++++-------------------------
drivers/media/usb/uvc/uvcvideo.h | 25 +++++++++++++--
2 files changed, 45 insertions(+), 46 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_status.c b/drivers/media/usb/uvc/uvc_status.c
index 7518ffce22ed..00f4036d0683 100644
--- a/drivers/media/usb/uvc/uvc_status.c
+++ b/drivers/media/usb/uvc/uvc_status.c
@@ -73,38 +73,24 @@ static void uvc_input_report_key(struct uvc_device *dev, unsigned int code,
/* --------------------------------------------------------------------------
* Status interrupt endpoint
*/
-struct uvc_streaming_status {
- u8 bStatusType;
- u8 bOriginator;
- u8 bEvent;
- u8 bValue[];
-} __packed;
-
-struct uvc_control_status {
- u8 bStatusType;
- u8 bOriginator;
- u8 bEvent;
- u8 bSelector;
- u8 bAttribute;
- u8 bValue[];
-} __packed;
-
static void uvc_event_streaming(struct uvc_device *dev,
- struct uvc_streaming_status *status, int len)
+ struct uvc_status *status, int len)
{
- if (len < 3) {
+ if (len <= offsetof(struct uvc_status, bEvent)) {
uvc_dbg(dev, STATUS,
"Invalid streaming status event received\n");
return;
}

if (status->bEvent == 0) {
- if (len < 4)
+ if (len <= offsetof(struct uvc_status, streaming))
return;
+
uvc_dbg(dev, STATUS, "Button (intf %u) %s len %d\n",
status->bOriginator,
- status->bValue[0] ? "pressed" : "released", len);
- uvc_input_report_key(dev, KEY_CAMERA, status->bValue[0]);
+ status->streaming.button ? "pressed" : "released", len);
+ uvc_input_report_key(dev, KEY_CAMERA,
+ status->streaming.button);
} else {
uvc_dbg(dev, STATUS, "Stream %u error event %02x len %d\n",
status->bOriginator, status->bEvent, len);
@@ -131,7 +117,7 @@ static struct uvc_control *uvc_event_entity_find_ctrl(struct uvc_entity *entity,
}

static struct uvc_control *uvc_event_find_ctrl(struct uvc_device *dev,
- const struct uvc_control_status *status,
+ const struct uvc_status *status,
struct uvc_video_chain **chain)
{
list_for_each_entry((*chain), &dev->chains, list) {
@@ -143,7 +129,7 @@ static struct uvc_control *uvc_event_find_ctrl(struct uvc_device *dev,
continue;

ctrl = uvc_event_entity_find_ctrl(entity,
- status->bSelector);
+ status->control.bSelector);
if (ctrl)
return ctrl;
}
@@ -153,7 +139,7 @@ static struct uvc_control *uvc_event_find_ctrl(struct uvc_device *dev,
}

static bool uvc_event_control(struct urb *urb,
- const struct uvc_control_status *status, int len)
+ const struct uvc_status *status, int len)
{
static const char *attrs[] = { "value", "info", "failure", "min", "max" };
struct uvc_device *dev = urb->context;
@@ -161,24 +147,24 @@ static bool uvc_event_control(struct urb *urb,
struct uvc_control *ctrl;

if (len < 6 || status->bEvent != 0 ||
- status->bAttribute >= ARRAY_SIZE(attrs)) {
+ status->control.bAttribute >= ARRAY_SIZE(attrs)) {
uvc_dbg(dev, STATUS, "Invalid control status event received\n");
return false;
}

uvc_dbg(dev, STATUS, "Control %u/%u %s change len %d\n",
- status->bOriginator, status->bSelector,
- attrs[status->bAttribute], len);
+ status->bOriginator, status->control.bSelector,
+ attrs[status->control.bAttribute], len);

/* Find the control. */
ctrl = uvc_event_find_ctrl(dev, status, &chain);
if (!ctrl)
return false;

- switch (status->bAttribute) {
+ switch (status->control.bAttribute) {
case UVC_CTRL_VALUE_CHANGE:
return uvc_ctrl_status_event_async(urb, chain, ctrl,
- status->bValue);
+ status->control.bValue);

case UVC_CTRL_INFO_CHANGE:
case UVC_CTRL_FAILURE_CHANGE:
@@ -214,28 +200,22 @@ static void uvc_status_complete(struct urb *urb)

len = urb->actual_length;
if (len > 0) {
- switch (dev->status[0] & 0x0f) {
+ switch (dev->status->bStatusType & 0x0f) {
case UVC_STATUS_TYPE_CONTROL: {
- struct uvc_control_status *status =
- (struct uvc_control_status *)dev->status;
-
- if (uvc_event_control(urb, status, len))
+ if (uvc_event_control(urb, dev->status, len))
/* The URB will be resubmitted in work context. */
return;
break;
}

case UVC_STATUS_TYPE_STREAMING: {
- struct uvc_streaming_status *status =
- (struct uvc_streaming_status *)dev->status;
-
- uvc_event_streaming(dev, status, len);
+ uvc_event_streaming(dev, dev->status, len);
break;
}

default:
uvc_dbg(dev, STATUS, "Unknown status event type %u\n",
- dev->status[0]);
+ dev->status->bStatusType);
break;
}
}
@@ -259,12 +239,12 @@ int uvc_status_init(struct uvc_device *dev)

uvc_input_init(dev);

- dev->status = kzalloc(UVC_MAX_STATUS_SIZE, GFP_KERNEL);
- if (dev->status == NULL)
+ dev->status = kzalloc(sizeof(*dev->status), GFP_KERNEL);
+ if (!dev->status)
return -ENOMEM;

dev->int_urb = usb_alloc_urb(0, GFP_KERNEL);
- if (dev->int_urb == NULL) {
+ if (!dev->int_urb) {
kfree(dev->status);
return -ENOMEM;
}
@@ -281,7 +261,7 @@ int uvc_status_init(struct uvc_device *dev)
interval = fls(interval) - 1;

usb_fill_int_urb(dev->int_urb, dev->udev, pipe,
- dev->status, UVC_MAX_STATUS_SIZE, uvc_status_complete,
+ dev->status, sizeof(*dev->status), uvc_status_complete,
dev, interval);

return 0;
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index df93db259312..84326991ec36 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -51,8 +51,6 @@
#define UVC_URBS 5
/* Maximum number of packets per URB. */
#define UVC_MAX_PACKETS 32
-/* Maximum status buffer size in bytes of interrupt URB. */
-#define UVC_MAX_STATUS_SIZE 16

#define UVC_CTRL_CONTROL_TIMEOUT 5000
#define UVC_CTRL_STREAMING_TIMEOUT 5000
@@ -527,6 +525,26 @@ struct uvc_device_info {
const struct uvc_control_mapping **mappings;
};

+struct uvc_status_streaming {
+ u8 button;
+} __packed;
+
+struct uvc_status_control {
+ u8 bSelector;
+ u8 bAttribute;
+ u8 bValue[11];
+} __packed;
+
+struct uvc_status {
+ u8 bStatusType;
+ u8 bOriginator;
+ u8 bEvent;
+ union {
+ struct uvc_status_control control;
+ struct uvc_status_streaming streaming;
+ };
+} __packed;
+
struct uvc_device {
struct usb_device *udev;
struct usb_interface *intf;
@@ -559,7 +577,8 @@ struct uvc_device {
/* Status Interrupt Endpoint */
struct usb_host_endpoint *int_ep;
struct urb *int_urb;
- u8 *status;
+ struct uvc_status *status;
+
struct input_dev *input;
char input_phys[64];

---
base-commit: 0ec5a38bf8499f403f81cb81a0e3a60887d1993c
change-id: 20221214-uvc-status-alloc-93becb783898
Best regards,
--
Ricardo Ribalda <ribalda@chromium.org>

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