V4L/DVB (9655): radio-mr800: fix unplug

This patch fixes problems(kernel oopses) with unplug of device while
it's working.
Patch adds disconnect_lock mutex, changes usb_amradio_close and
usb_amradio_disconnect functions and adds a lot of safety checks.

Signed-off-by: Alexey Klimov <klimov.linux@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

diff --git a/drivers/media/radio/radio-mr800.c b/drivers/media/radio/radio-mr800.c
index 6176001..7b7a1cf 100644 (file)
--- a/drivers/media/radio/radio-mr800.c
+++ b/drivers/media/radio/radio-mr800.c
@@ -141,6 +141,7 @@ struct amradio_device {
 
        unsigned char *buffer;
        struct mutex lock;      /* buffer locking */
+       struct mutex disconnect_lock;
        int curfreq;
        int stereo;
        int users;
@@ -207,6 +208,10 @@ static int amradio_stop(struct amradio_device *radio)
        int retval;
        int size;
 
+       /* safety check */
+       if (radio->removed)
+               return -EIO;
+
        mutex_lock(&radio->lock);
 
        radio->buffer[0] = 0x00;
@@ -240,6 +245,10 @@ static int amradio_setfreq(struct amradio_device *radio, int freq)
        int size;
        unsigned short freq_send = 0x13 + (freq >> 3) / 25;
 
+       /* safety check */
+       if (radio->removed)
+               return -EIO;
+
        mutex_lock(&radio->lock);
 
        radio->buffer[0] = 0x00;
@@ -293,18 +302,16 @@ static void usb_amradio_disconnect(struct usb_interface *intf)
 {
        struct amradio_device *radio = usb_get_intfdata(intf);
 
+       mutex_lock(&radio->disconnect_lock);
+       radio->removed = 1;
        usb_set_intfdata(intf, NULL);
 
-       if (radio) {
+       if (radio->users == 0) {
                video_unregister_device(radio->videodev);
-               radio->videodev = NULL;
-               if (radio->users) {
-                       kfree(radio->buffer);
-                       kfree(radio);
-               } else {
-                       radio->removed = 1;
-               }
+               kfree(radio->buffer);
+               kfree(radio);
        }
+       mutex_unlock(&radio->disconnect_lock);
 }
 
 /* vidioc_querycap - query device capabilities */
@@ -325,6 +332,10 @@ static int vidioc_g_tuner(struct file *file, void *priv,
 {
        struct amradio_device *radio = video_get_drvdata(video_devdata(file));
 
+       /* safety check */
+       if (radio->removed)
+               return -EIO;
+
        if (v->index > 0)
                return -EINVAL;
 
@@ -351,6 +362,12 @@ static int vidioc_g_tuner(struct file *file, void *priv,
 static int vidioc_s_tuner(struct file *file, void *priv,
                                struct v4l2_tuner *v)
 {
+       struct amradio_device *radio = video_get_drvdata(video_devdata(file));
+
+       /* safety check */
+       if (radio->removed)
+               return -EIO;
+
        if (v->index > 0)
                return -EINVAL;
        return 0;
@@ -362,6 +379,10 @@ static int vidioc_s_frequency(struct file *file, void *priv,
 {
        struct amradio_device *radio = video_get_drvdata(video_devdata(file));
 
+       /* safety check */
+       if (radio->removed)
+               return -EIO;
+
        radio->curfreq = f->frequency;
        if (amradio_setfreq(radio, radio->curfreq) < 0)
                amradio_dev_warn(&radio->videodev->dev,
@@ -375,6 +396,10 @@ static int vidioc_g_frequency(struct file *file, void *priv,
 {
        struct amradio_device *radio = video_get_drvdata(video_devdata(file));
 
+       /* safety check */
+       if (radio->removed)
+               return -EIO;
+
        f->type = V4L2_TUNER_RADIO;
        f->frequency = radio->curfreq;
        return 0;
@@ -401,6 +426,10 @@ static int vidioc_g_ctrl(struct file *file, void *priv,
 {
        struct amradio_device *radio = video_get_drvdata(video_devdata(file));
 
+       /* safety check */
+       if (radio->removed)
+               return -EIO;
+
        switch (ctrl->id) {
        case V4L2_CID_AUDIO_MUTE:
                ctrl->value = radio->muted;
@@ -415,6 +444,10 @@ static int vidioc_s_ctrl(struct file *file, void *priv,
 {
        struct amradio_device *radio = video_get_drvdata(video_devdata(file));
 
+       /* safety check */
+       if (radio->removed)
+               return -EIO;
+
        switch (ctrl->id) {
        case V4L2_CID_AUDIO_MUTE:
                if (ctrl->value) {
@@ -500,14 +533,26 @@ static int usb_amradio_open(struct inode *inode, struct file *file)
 static int usb_amradio_close(struct inode *inode, struct file *file)
 {
        struct amradio_device *radio = video_get_drvdata(video_devdata(file));
+       int retval;
 
        if (!radio)
                return -ENODEV;
+
+       mutex_lock(&radio->disconnect_lock);
        radio->users = 0;
        if (radio->removed) {
+               video_unregister_device(radio->videodev);
                kfree(radio->buffer);
                kfree(radio);
+
+       } else {
+               retval = amradio_stop(radio);
+               if (retval < 0)
+                       amradio_dev_warn(&radio->videodev->dev,
+                               "amradio_stop failed\n");
        }
+
+       mutex_unlock(&radio->disconnect_lock);
        return 0;
 }
 
@@ -607,6 +652,7 @@ static int usb_amradio_probe(struct usb_interface *intf,
        radio->usbdev = interface_to_usbdev(intf);
        radio->curfreq = 95.16 * FREQ_MUL;
 
+       mutex_init(&radio->disconnect_lock);
        mutex_init(&radio->lock);
 
        video_set_drvdata(radio->videodev, radio);