[media] [RFC] radio-mr800: locking fixes

- serialize the suspend and resume functions using the global lock.
- do not call usb_autopm_put_interface after a disconnect.
- fix a race when disconnecting the device.

Reported-by: David Ellingsworth <david@identd.dyndns.org>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Acked-by: David Ellingsworth<david@identd.dyndns.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 14 insertions, 3 deletions

diff --git a/drivers/media/radio/radio-mr800.c b/drivers/media/radio/radio-mr800.c
index 2f56b26cece9..b540e8072e92 100644
--- a/drivers/media/radio/radio-mr800.c
+++ b/drivers/media/radio/radio-mr800.c
@@ -284,9 +284,13 @@ static void usb_amradio_disconnect(struct usb_interface *intf)
         struct amradio_device *radio = to_amradio_dev(usb_get_intfdata(intf));
 
         mutex_lock(&radio->lock);
+        /* increase the device node's refcount */
+        get_device(&radio->videodev.dev);
         v4l2_device_disconnect(&radio->v4l2_dev);
-        mutex_unlock(&radio->lock);
         video_unregister_device(&radio->videodev);
+        mutex_unlock(&radio->lock);
+        /* decrease the device node's refcount, allowing it to be released */
+        put_device(&radio->videodev.dev);
 }
 
 /* vidioc_querycap - query device capabilities */
@@ -515,7 +519,8 @@ static int usb_amradio_close(struct file *file)
 {
         struct amradio_device *radio = file->private_data;
 
-        usb_autopm_put_interface(radio->intf);
+        if (video_is_registered(&radio->videodev))
+                usb_autopm_put_interface(radio->intf);
         return 0;
 }
 
@@ -524,10 +529,12 @@ static int usb_amradio_suspend(struct usb_interface *intf, pm_message_t message)
 {
         struct amradio_device *radio = to_amradio_dev(usb_get_intfdata(intf));
 
+        mutex_lock(&radio->lock);
         if (!radio->muted && radio->initialized) {
                 amradio_set_mute(radio, AMRADIO_STOP);
                 radio->muted = 0;
         }
+        mutex_unlock(&radio->lock);
 
         dev_info(&intf->dev, "going into suspend..\n");
         return 0;
@@ -538,8 +545,9 @@ static int usb_amradio_resume(struct usb_interface *intf)
 {
         struct amradio_device *radio = to_amradio_dev(usb_get_intfdata(intf));
 
+        mutex_lock(&radio->lock);
         if (unlikely(!radio->initialized))
-                return 0;
+                goto unlock;
 
         if (radio->stereo)
                 amradio_set_stereo(radio, WANT_STEREO);
@@ -551,6 +559,9 @@ static int usb_amradio_resume(struct usb_interface *intf)
         if (!radio->muted)
                 amradio_set_mute(radio, AMRADIO_START);
 
+unlock:
+        mutex_unlock(&radio->lock);
+
         dev_info(&intf->dev, "coming out of suspend..\n");
         return 0;
 }