2021-09-01 22:09:01

by Cai,Huoqing

Subject: [PATCH v3] usb: stkwebcam: Update the reference count of the usb device structure

Use usb_get_dev() to increment the reference count of the usb device
structure in order to avoid releasing the structure while it is still in
use. And use usb_put_dev() to decrement the reference count and thus,
when it will be equal to 0 the structure will be released.

Signed-off-by: Cai Huoqing <[email protected]>
---
v2->v3:
*call usb_put_dev() in the error path of stk_camera_probe
*move v4l2_ctrl_handler_free/v4l2_device_unregister/kfree(dev)
from stk_camera_disconnect() to stk_v4l_dev_release()

drivers/media/usb/stkwebcam/stk-webcam.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/media/usb/stkwebcam/stk-webcam.c b/drivers/media/usb/stkwebcam/stk-webcam.c
index 0e231e576dc3..9f445e6ab5fa 100644
--- a/drivers/media/usb/stkwebcam/stk-webcam.c
+++ b/drivers/media/usb/stkwebcam/stk-webcam.c
@@ -1234,6 +1234,11 @@ static void stk_v4l_dev_release(struct video_device *vd)
if (dev->sio_bufs != NULL || dev->isobufs != NULL)
pr_err("We are leaking memory\n");
usb_put_intf(dev->interface);
+ usb_put_dev(dev->udev);
+
+ v4l2_ctrl_handler_free(&dev->hdl);
+ v4l2_device_unregister(&dev->v4l2_dev);
+ kfree(dev);
}

static const struct video_device stk_v4l_data = {
@@ -1309,7 +1314,7 @@ static int stk_camera_probe(struct usb_interface *interface,
init_waitqueue_head(&dev->wait_frame);
dev->first_init = 1; /* webcam LED management */

- dev->udev = udev;
+ dev->udev = usb_get_dev(udev);
dev->interface = interface;
usb_get_intf(interface);

@@ -1365,6 +1370,7 @@ static int stk_camera_probe(struct usb_interface *interface,

error_put:
usb_put_intf(interface);
+ usb_put_dev(dev->udev);
error:
v4l2_ctrl_handler_free(hdl);
v4l2_device_unregister(&dev->v4l2_dev);
@@ -1385,9 +1391,6 @@ static void stk_camera_disconnect(struct usb_interface *interface)
video_device_node_name(&dev->vdev));

video_unregister_device(&dev->vdev);
- v4l2_ctrl_handler_free(&dev->hdl);
- v4l2_device_unregister(&dev->v4l2_dev);
- kfree(dev);
}

#ifdef CONFIG_PM
--
2.25.1

2021-09-02 12:20:33

by Cai,Huoqing

Subject: RE: [PATCH v3] usb: stkwebcam: Update the reference count of the usb device structure

Hello,

+Cc Hans Verkuil <[email protected]>
Cai
> Subject: [PATCH v3] usb: stkwebcam: Update the reference count of the usb
> device structure
>
> Use usb_get_dev() to increment the reference count of the usb device
> structure in order to avoid releasing the structure while it is still in
> use. And use usb_put_dev() to decrement the reference count and thus,
> when it will be equal to 0 the structure will be released.
>
> Signed-off-by: Cai Huoqing <[email protected]>
> ---
> v2->v3:
> *call usb_put_dev() in the error path of stk_camera_probe
> *move v4l2_ctrl_handler_free/v4l2_device_unregister/kfree(dev)
> from stk_camera_disconnect() to stk_v4l_dev_release()
>
> drivers/media/usb/stkwebcam/stk-webcam.c | 11 +++++++----
> 1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/media/usb/stkwebcam/stk-webcam.c
> b/drivers/media/usb/stkwebcam/stk-webcam.c
> index 0e231e576dc3..9f445e6ab5fa 100644
> --- a/drivers/media/usb/stkwebcam/stk-webcam.c
> +++ b/drivers/media/usb/stkwebcam/stk-webcam.c
> @@ -1234,6 +1234,11 @@ static void stk_v4l_dev_release(struct
> video_device *vd)
> if (dev->sio_bufs != NULL || dev->isobufs != NULL)
> pr_err("We are leaking memory\n");
> usb_put_intf(dev->interface);
> + usb_put_dev(dev->udev);
> +
> + v4l2_ctrl_handler_free(&dev->hdl);
> + v4l2_device_unregister(&dev->v4l2_dev);
> + kfree(dev);
> }
>
> static const struct video_device stk_v4l_data = {
> @@ -1309,7 +1314,7 @@ static int stk_camera_probe(struct usb_interface
> *interface,
> init_waitqueue_head(&dev->wait_frame);
> dev->first_init = 1; /* webcam LED management */
>
> - dev->udev = udev;
> + dev->udev = usb_get_dev(udev);
> dev->interface = interface;
> usb_get_intf(interface);
>
> @@ -1365,6 +1370,7 @@ static int stk_camera_probe(struct usb_interface
> *interface,
>
> error_put:
> usb_put_intf(interface);
> + usb_put_dev(dev->udev);
> error:
> v4l2_ctrl_handler_free(hdl);
> v4l2_device_unregister(&dev->v4l2_dev);
> @@ -1385,9 +1391,6 @@ static void stk_camera_disconnect(struct
> usb_interface *interface)
> video_device_node_name(&dev->vdev));
>
> video_unregister_device(&dev->vdev);
> - v4l2_ctrl_handler_free(&dev->hdl);
> - v4l2_device_unregister(&dev->v4l2_dev);
> - kfree(dev);
> }
>
> #ifdef CONFIG_PM
> --
> 2.25.1