media: s2255: Use refcount_t instead of atomic_t for num_channels

Use an API that resembles more the actual use of num_channels.

Found by cocci:
drivers/media/usb/s2255/s2255drv.c:2362:5-24: WARNING: atomic_dec_and_test variation before object free at line 2363.
drivers/media/usb/s2255/s2255drv.c:1557:5-24: WARNING: atomic_dec_and_test variation before object free at line 1558.

Link: https://lore.kernel.org/linux-media/20240429-fix-cocci-v3-11-3c4865f5a4b0@chromium.org
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

diff --git a/drivers/media/usb/s2255/s2255drv.c b/drivers/media/usb/s2255/s2255drv.c
index 8e1de1e8bd127dfdfbb6434d8e55a7f55f016d80..a6e450181fd014616a2f4e6bcb72f2ba8b5087ac 100644 (file)
--- a/drivers/media/usb/s2255/s2255drv.c
+++ b/drivers/media/usb/s2255/s2255drv.c
@@ -247,7 +247,7 @@ struct s2255_vc {
 struct s2255_dev {
        struct s2255_vc         vc[MAX_CHANNELS];
        struct v4l2_device      v4l2_dev;
-       atomic_t                num_channels;
+       refcount_t              num_channels;
        int                     frames;
        struct mutex            lock;   /* channels[].vdev.lock */
        struct mutex            cmdlock; /* protects cmdbuf */
@@ -1550,11 +1550,11 @@ static void s2255_video_device_release(struct video_device *vdev)
                container_of(vdev, struct s2255_vc, vdev);
 
        dprintk(dev, 4, "%s, chnls: %d\n", __func__,
-               atomic_read(&dev->num_channels));
+               refcount_read(&dev->num_channels));
 
        v4l2_ctrl_handler_free(&vc->hdl);
 
-       if (atomic_dec_and_test(&dev->num_channels))
+       if (refcount_dec_and_test(&dev->num_channels))
                s2255_destroy(dev);
        return;
 }
@@ -1659,7 +1659,7 @@ static int s2255_probe_v4l(struct s2255_dev *dev)
                                "failed to register video device!\n");
                        break;
                }
-               atomic_inc(&dev->num_channels);
+               refcount_inc(&dev->num_channels);
                v4l2_info(&dev->v4l2_dev, "V4L2 device registered as %s\n",
                          video_device_node_name(&vc->vdev));
 
@@ -1667,11 +1667,11 @@ static int s2255_probe_v4l(struct s2255_dev *dev)
        pr_info("Sensoray 2255 V4L driver Revision: %s\n",
                S2255_VERSION);
        /* if no channels registered, return error and probe will fail*/
-       if (atomic_read(&dev->num_channels) == 0) {
+       if (refcount_read(&dev->num_channels) == 0) {
                v4l2_device_unregister(&dev->v4l2_dev);
                return ret;
        }
-       if (atomic_read(&dev->num_channels) != MAX_CHANNELS)
+       if (refcount_read(&dev->num_channels) != MAX_CHANNELS)
                pr_warn("s2255: Not all channels available.\n");
        return 0;
 }
@@ -2221,7 +2221,7 @@ static int s2255_probe(struct usb_interface *interface,
                goto errorFWDATA1;
        }
 
-       atomic_set(&dev->num_channels, 0);
+       refcount_set(&dev->num_channels, 0);
        dev->pid = id->idProduct;
        dev->fw_data = kzalloc(sizeof(struct s2255_fw), GFP_KERNEL);
        if (!dev->fw_data)
@@ -2341,12 +2341,12 @@ static void s2255_disconnect(struct usb_interface *interface)
 {
        struct s2255_dev *dev = to_s2255_dev(usb_get_intfdata(interface));
        int i;
-       int channels = atomic_read(&dev->num_channels);
+       int channels = refcount_read(&dev->num_channels);
        mutex_lock(&dev->lock);
        v4l2_device_disconnect(&dev->v4l2_dev);
        mutex_unlock(&dev->lock);
        /*see comments in the uvc_driver.c usb disconnect function */
-       atomic_inc(&dev->num_channels);
+       refcount_inc(&dev->num_channels);
        /* unregister each video device. */
        for (i = 0; i < channels; i++)
                video_unregister_device(&dev->vc[i].vdev);
@@ -2359,7 +2359,7 @@ static void s2255_disconnect(struct usb_interface *interface)
                dev->vc[i].vidstatus_ready = 1;
                wake_up(&dev->vc[i].wait_vidstatus);
        }
-       if (atomic_dec_and_test(&dev->num_channels))
+       if (refcount_dec_and_test(&dev->num_channels))
                s2255_destroy(dev);
        dev_info(&interface->dev, "%s\n", __func__);
 }