[PATCH v4 1/2] em28xx: Only deallocate struct em28xx after finishing all extensions

[PATCH v4 1/2] em28xx: Only deallocate struct em28xx after finishing all extensions

[Mauro Carvalho Chehab]

We can't free struct em28xx while one of the extensions is still
using it.

So, add a kref() to control it, freeing it only after the
extensions fini calls.

Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
---
 drivers/media/usb/em28xx/em28xx-audio.c |  7 ++++++-
 drivers/media/usb/em28xx/em28xx-cards.c | 32 +++++++++++++++++++++++++-------
 drivers/media/usb/em28xx/em28xx-dvb.c   |  5 ++++-
 drivers/media/usb/em28xx/em28xx-input.c |  8 +++++++-
 drivers/media/usb/em28xx/em28xx-video.c | 15 ++++++++-------
 drivers/media/usb/em28xx/em28xx.h       |  8 ++++++--
 6 files changed, 56 insertions(+), 19 deletions(-)

diff --git a/drivers/media/usb/em28xx/em28xx-audio.c b/drivers/media/usb/em28xx/em28xx-audio.c
index 0f5b6f3e7a3f..f75c0a5494d6 100644
--- a/drivers/media/usb/em28xx/em28xx-audio.c
+++ b/drivers/media/usb/em28xx/em28xx-audio.c
@@ -301,6 +301,7 @@ static int snd_em28xx_capture_open(struct snd_pcm_substream *substream)
 			goto err;
 	}
 
+	kref_get(&dev->ref);
 	dev->adev.users++;
 	mutex_unlock(&dev->lock);
 
@@ -341,6 +342,7 @@ static int snd_em28xx_pcm_close(struct snd_pcm_substream *substream)
 		substream->runtime->dma_area = NULL;
 	}
 	mutex_unlock(&dev->lock);
+	kref_put(&dev->ref, em28xx_free_device);
 
 	return 0;
 }
@@ -895,6 +897,8 @@ static int em28xx_audio_init(struct em28xx *dev)
 
 	em28xx_info("Binding audio extension\n");
 
+	kref_get(&dev->ref);
+
 	printk(KERN_INFO "em28xx-audio.c: Copyright (C) 2006 Markus "
 			 "Rechberger\n");
 	printk(KERN_INFO
@@ -967,7 +971,7 @@ static int em28xx_audio_fini(struct em28xx *dev)
 	if (dev == NULL)
 		return 0;
 
-	if (dev->has_alsa_audio != 1) {
+	if (!dev->has_alsa_audio) {
 		/* This device does not support the extension (in this case
 		   the device is expecting the snd-usb-audio module or
 		   doesn't have analog audio support at all) */
@@ -986,6 +990,7 @@ static int em28xx_audio_fini(struct em28xx *dev)
 		dev->adev.sndcard = NULL;
 	}
 
+	kref_put(&dev->ref, em28xx_free_device);
 	return 0;
 }
 
diff --git a/drivers/media/usb/em28xx/em28xx-cards.c b/drivers/media/usb/em28xx/em28xx-cards.c
index 2fb300e882f0..015e3731a1c0 100644
--- a/drivers/media/usb/em28xx/em28xx-cards.c
+++ b/drivers/media/usb/em28xx/em28xx-cards.c
@@ -2939,7 +2939,7 @@ static void flush_request_modules(struct em28xx *dev)
  * unregisters the v4l2,i2c and usb devices
  * called when the device gets disconnected or at module unload
 */
-void em28xx_release_resources(struct em28xx *dev)
+static void em28xx_release_resources(struct em28xx *dev)
 {
 	/*FIXME: I2C IR should be disconnected */
 
@@ -2956,7 +2956,27 @@ void em28xx_release_resources(struct em28xx *dev)
 
 	mutex_unlock(&dev->lock);
 };
-EXPORT_SYMBOL_GPL(em28xx_release_resources);
+
+/**
+ * em28xx_free_defice() - Free em28xx device
+ *
+ * @ref: struct kref for em28xx device
+ *
+ * This is called when all extensions and em28xx core unregisters a device
+ */
+void em28xx_free_device(struct kref *ref)
+{
+	struct em28xx *dev = kref_to_dev(ref);
+
+	em28xx_info("Freeing device\n");
+
+	if (!dev->disconnected)
+		em28xx_release_resources(dev);
+
+	kfree(dev->alt_max_pkt_size_isoc);
+	kfree(dev);
+}
+EXPORT_SYMBOL_GPL(em28xx_free_device);
 
 /*
  * em28xx_init_dev()
@@ -3409,6 +3429,8 @@ static int em28xx_usb_probe(struct usb_interface *interface,
 			    dev->dvb_xfer_bulk ? "bulk" : "isoc");
 	}
 
+	kref_init(&dev->ref);
+
 	request_modules(dev);
 
 	/* Should be the last thing to do, to avoid newer udev's to
@@ -3453,11 +3475,7 @@ static void em28xx_usb_disconnect(struct usb_interface *interface)
 	em28xx_close_extension(dev);
 
 	em28xx_release_resources(dev);
-
-	if (!dev->users) {
-		kfree(dev->alt_max_pkt_size_isoc);
-		kfree(dev);
-	}
+	kref_put(&dev->ref, em28xx_free_device);
 }
 
 static int em28xx_usb_suspend(struct usb_interface *interface,
diff --git a/drivers/media/usb/em28xx/em28xx-dvb.c b/drivers/media/usb/em28xx/em28xx-dvb.c
index d4986bdfbdc3..cacdca3a3412 100644
--- a/drivers/media/usb/em28xx/em28xx-dvb.c
+++ b/drivers/media/usb/em28xx/em28xx-dvb.c
@@ -1043,7 +1043,6 @@ static int em28xx_dvb_init(struct em28xx *dev)
 	em28xx_info("Binding DVB extension\n");
 
 	dvb = kzalloc(sizeof(struct em28xx_dvb), GFP_KERNEL);
-
 	if (dvb == NULL) {
 		em28xx_info("em28xx_dvb: memory allocation failed\n");
 		return -ENOMEM;
@@ -1521,6 +1520,9 @@ static int em28xx_dvb_init(struct em28xx *dev)
 	dvb->adapter.mfe_shared = mfe_shared;
 
 	em28xx_info("DVB extension successfully initialized\n");
+
+	kref_get(&dev->ref);
+
 ret:
 	em28xx_set_mode(dev, EM28XX_SUSPEND);
 	mutex_unlock(&dev->lock);
@@ -1577,6 +1579,7 @@ static int em28xx_dvb_fini(struct em28xx *dev)
 		em28xx_unregister_dvb(dvb);
 		kfree(dvb);
 		dev->dvb = NULL;
+		kref_put(&dev->ref, em28xx_free_device);
 	}
 
 	return 0;
diff --git a/drivers/media/usb/em28xx/em28xx-input.c b/drivers/media/usb/em28xx/em28xx-input.c
index 47a2c1dcccbf..2a9bf667f208 100644
--- a/drivers/media/usb/em28xx/em28xx-input.c
+++ b/drivers/media/usb/em28xx/em28xx-input.c
@@ -676,6 +676,8 @@ static int em28xx_ir_init(struct em28xx *dev)
 		return 0;
 	}
 
+	kref_get(&dev->ref);
+
 	if (dev->board.buttons)
 		em28xx_init_buttons(dev);
 
@@ -816,7 +818,7 @@ static int em28xx_ir_fini(struct em28xx *dev)
 
 	/* skip detach on non attached boards */
 	if (!ir)
-		return 0;
+		goto ref_put;
 
 	if (ir->rc)
 		rc_unregister_device(ir->rc);
@@ -824,6 +826,10 @@ static int em28xx_ir_fini(struct em28xx *dev)
 	/* done */
 	kfree(ir);
 	dev->ir = NULL;
+
+ref_put:
+	kref_put(&dev->ref, em28xx_free_device);
+
 	return 0;
 }
 
diff --git a/drivers/media/usb/em28xx/em28xx-video.c b/drivers/media/usb/em28xx/em28xx-video.c
index 19af6b3e9e2b..32aa55f033fc 100644
--- a/drivers/media/usb/em28xx/em28xx-video.c
+++ b/drivers/media/usb/em28xx/em28xx-video.c
@@ -1837,7 +1837,6 @@ static int em28xx_v4l2_open(struct file *filp)
 			video_device_node_name(vdev), v4l2_type_names[fh_type],
 			dev->users);
 
-
 	if (mutex_lock_interruptible(&dev->lock))
 		return -ERESTARTSYS;
 	fh = kzalloc(sizeof(struct em28xx_fh), GFP_KERNEL);
@@ -1869,6 +1868,7 @@ static int em28xx_v4l2_open(struct file *filp)
 		v4l2_device_call_all(&dev->v4l2_dev, 0, tuner, s_radio);
 	}
 
+	kref_get(&dev->ref);
 	dev->users++;
 
 	mutex_unlock(&dev->lock);
@@ -1926,9 +1926,8 @@ static int em28xx_v4l2_fini(struct em28xx *dev)
 		dev->clk = NULL;
 	}
 
-	if (dev->users)
-		em28xx_warn("Device is open ! Memory deallocation is deferred on last close.\n");
 	mutex_unlock(&dev->lock);
+	kref_put(&dev->ref, em28xx_free_device);
 
 	return 0;
 }
@@ -1976,11 +1975,9 @@ static int em28xx_v4l2_close(struct file *filp)
 	mutex_lock(&dev->lock);
 
 	if (dev->users == 1) {
-		/* free the remaining resources if device is disconnected */
-		if (dev->disconnected) {
-			kfree(dev->alt_max_pkt_size_isoc);
+		/* No sense to try to write to the device */
+		if (dev->disconnected)
 			goto exit;
-		}
 
 		/* Save some power by putting tuner to sleep */
 		v4l2_device_call_all(&dev->v4l2_dev, 0, core, s_power, 0);
@@ -2001,6 +1998,8 @@ static int em28xx_v4l2_close(struct file *filp)
 exit:
 	dev->users--;
 	mutex_unlock(&dev->lock);
+	kref_put(&dev->ref, em28xx_free_device);
+
 	return 0;
 }
 
@@ -2515,6 +2514,8 @@ static int em28xx_v4l2_init(struct em28xx *dev)
 
 	em28xx_info("V4L2 extension successfully initialized\n");
 
+	kref_get(&dev->ref);
+
 	mutex_unlock(&dev->lock);
 	return 0;
 
diff --git a/drivers/media/usb/em28xx/em28xx.h b/drivers/media/usb/em28xx/em28xx.h
index 9e44f5bfc48b..2051fc9fb932 100644
--- a/drivers/media/usb/em28xx/em28xx.h
+++ b/drivers/media/usb/em28xx/em28xx.h
@@ -32,6 +32,7 @@
 #include <linux/workqueue.h>
 #include <linux/i2c.h>
 #include <linux/mutex.h>
+#include <linux/kref.h>
 #include <linux/videodev2.h>
 
 #include <media/videobuf2-vmalloc.h>
@@ -536,9 +537,10 @@ struct em28xx_i2c_bus {
 	enum em28xx_i2c_algo_type algo_type;
 };
 
-
 /* main device struct */
 struct em28xx {
+	struct kref ref;
+
 	/* generic device properties */
 	char name[30];		/* name (including minor) of the device */
 	int model;		/* index in the device_data struct */
@@ -710,6 +712,8 @@ struct em28xx {
 	struct em28xx_dvb *dvb;
 };
 
+#define kref_to_dev(d) container_of(d, struct em28xx, ref)
+
 struct em28xx_ops {
 	struct list_head next;
 	char *name;
@@ -771,7 +775,7 @@ extern struct em28xx_board em28xx_boards[];
 extern struct usb_device_id em28xx_id_table[];
 int em28xx_tuner_callback(void *ptr, int component, int command, int arg);
 void em28xx_setup_xc3028(struct em28xx *dev, struct xc2028_ctrl *ctl);
-void em28xx_release_resources(struct em28xx *dev);
+void em28xx_free_device(struct kref *ref);
 
 /* Provided by em28xx-camera.c */
 int em28xx_detect_sensor(struct em28xx *dev);
-- 
1.8.5.3

[PATCH 2/2] em28xx-dvb: remove one level of identation at fini callback

[Mauro Carvalho Chehab]

Simplify the logic a little by removing one level of identation.
Also, it only makes sense to print something if the .fini callback
is actually doing something.

Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
---
 drivers/media/usb/em28xx/em28xx-dvb.c | 48 +++++++++++++++++++----------------
 1 file changed, 26 insertions(+), 22 deletions(-)

diff --git a/drivers/media/usb/em28xx/em28xx-dvb.c b/drivers/media/usb/em28xx/em28xx-dvb.c
index cacdca3a3412..6638394b3457 100644
--- a/drivers/media/usb/em28xx/em28xx-dvb.c
+++ b/drivers/media/usb/em28xx/em28xx-dvb.c
@@ -1543,6 +1543,9 @@ static inline void prevent_sleep(struct dvb_frontend_ops *ops)
 
 static int em28xx_dvb_fini(struct em28xx *dev)
 {
+	struct em28xx_dvb *dvb;
+	struct i2c_client *client;
+
 	if (dev->is_audio_only) {
 		/* Shouldn't initialize IR for this interface */
 		return 0;
@@ -1553,35 +1556,36 @@ static int em28xx_dvb_fini(struct em28xx *dev)
 		return 0;
 	}
 
-	em28xx_info("Closing DVB extension");
+	if (!dev->dvb)
+		return 0;
 
-	if (dev->dvb) {
-		struct em28xx_dvb *dvb = dev->dvb;
-		struct i2c_client *client = dvb->i2c_client_tuner;
+	em28xx_info("Closing DVB extension");
 
-		em28xx_uninit_usb_xfer(dev, EM28XX_DIGITAL_MODE);
+	dvb = dev->dvb;
+	client = dvb->i2c_client_tuner;
 
-		if (dev->disconnected) {
-			/* We cannot tell the device to sleep
-			 * once it has been unplugged. */
-			if (dvb->fe[0])
-				prevent_sleep(&dvb->fe[0]->ops);
-			if (dvb->fe[1])
-				prevent_sleep(&dvb->fe[1]->ops);
-		}
+	em28xx_uninit_usb_xfer(dev, EM28XX_DIGITAL_MODE);
 
-		/* remove I2C tuner */
-		if (client) {
-			module_put(client->dev.driver->owner);
-			i2c_unregister_device(client);
-		}
+	if (dev->disconnected) {
+		/* We cannot tell the device to sleep
+		 * once it has been unplugged. */
+		if (dvb->fe[0])
+			prevent_sleep(&dvb->fe[0]->ops);
+		if (dvb->fe[1])
+			prevent_sleep(&dvb->fe[1]->ops);
+	}
 
-		em28xx_unregister_dvb(dvb);
-		kfree(dvb);
-		dev->dvb = NULL;
-		kref_put(&dev->ref, em28xx_free_device);
+	/* remove I2C tuner */
+	if (client) {
+		module_put(client->dev.driver->owner);
+		i2c_unregister_device(client);
 	}
 
+	em28xx_unregister_dvb(dvb);
+	kfree(dvb);
+	dev->dvb = NULL;
+	kref_put(&dev->ref, em28xx_free_device);
+
 	return 0;
 }
 
-- 
1.8.5.3

Re: [PATCH 2/2] em28xx-dvb: remove one level of identation at fini callback

[Frank Schäfer]

Am 08.03.2014 13:19, schrieb Mauro Carvalho Chehab:
> Simplify the logic a little by removing one level of identation.
> Also, it only makes sense to print something if the .fini callback
> is actually doing something.
>
> Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
> ---
>  drivers/media/usb/em28xx/em28xx-dvb.c | 48 +++++++++++++++++++----------------
>  1 file changed, 26 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/media/usb/em28xx/em28xx-dvb.c b/drivers/media/usb/em28xx/em28xx-dvb.c
> index cacdca3a3412..6638394b3457 100644
> --- a/drivers/media/usb/em28xx/em28xx-dvb.c
> +++ b/drivers/media/usb/em28xx/em28xx-dvb.c
> @@ -1543,6 +1543,9 @@ static inline void prevent_sleep(struct dvb_frontend_ops *ops)
>  
>  static int em28xx_dvb_fini(struct em28xx *dev)
>  {
> +	struct em28xx_dvb *dvb;
> +	struct i2c_client *client;
> +
>  	if (dev->is_audio_only) {
>  		/* Shouldn't initialize IR for this interface */
>  		return 0;
> @@ -1553,35 +1556,36 @@ static int em28xx_dvb_fini(struct em28xx *dev)
>  		return 0;
>  	}
>  
> -	em28xx_info("Closing DVB extension");
> +	if (!dev->dvb)
> +		return 0;
>  
> -	if (dev->dvb) {
> -		struct em28xx_dvb *dvb = dev->dvb;
> -		struct i2c_client *client = dvb->i2c_client_tuner;
> +	em28xx_info("Closing DVB extension");
>  
> -		em28xx_uninit_usb_xfer(dev, EM28XX_DIGITAL_MODE);
> +	dvb = dev->dvb;
> +	client = dvb->i2c_client_tuner;
>  
> -		if (dev->disconnected) {
> -			/* We cannot tell the device to sleep
> -			 * once it has been unplugged. */
> -			if (dvb->fe[0])
> -				prevent_sleep(&dvb->fe[0]->ops);
> -			if (dvb->fe[1])
> -				prevent_sleep(&dvb->fe[1]->ops);
> -		}
> +	em28xx_uninit_usb_xfer(dev, EM28XX_DIGITAL_MODE);
>  
> -		/* remove I2C tuner */
> -		if (client) {
> -			module_put(client->dev.driver->owner);
> -			i2c_unregister_device(client);
> -		}
> +	if (dev->disconnected) {
> +		/* We cannot tell the device to sleep
> +		 * once it has been unplugged. */
> +		if (dvb->fe[0])
> +			prevent_sleep(&dvb->fe[0]->ops);
> +		if (dvb->fe[1])
> +			prevent_sleep(&dvb->fe[1]->ops);
> +	}
>  
> -		em28xx_unregister_dvb(dvb);
> -		kfree(dvb);
> -		dev->dvb = NULL;
> -		kref_put(&dev->ref, em28xx_free_device);
> +	/* remove I2C tuner */
> +	if (client) {
> +		module_put(client->dev.driver->owner);
> +		i2c_unregister_device(client);
>  	}
>  
> +	em28xx_unregister_dvb(dvb);
> +	kfree(dvb);
> +	dev->dvb = NULL;
> +	kref_put(&dev->ref, em28xx_free_device);
> +
>  	return 0;
>  }
>  

Reviewed-by: Frank Schäfer <fschaefer.oss@googlemail.com>

Re: [PATCH v4 1/2] em28xx: Only deallocate struct em28xx after finishing all extensions

[Frank Schäfer]

Am 08.03.2014 13:19, schrieb Mauro Carvalho Chehab:
> We can't free struct em28xx while one of the extensions is still
> using it.
>
> So, add a kref() to control it, freeing it only after the
> extensions fini calls.
>
> Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
> ---
>  drivers/media/usb/em28xx/em28xx-audio.c |  7 ++++++-
>  drivers/media/usb/em28xx/em28xx-cards.c | 32 +++++++++++++++++++++++++-------
>  drivers/media/usb/em28xx/em28xx-dvb.c   |  5 ++++-
>  drivers/media/usb/em28xx/em28xx-input.c |  8 +++++++-
>  drivers/media/usb/em28xx/em28xx-video.c | 15 ++++++++-------
>  drivers/media/usb/em28xx/em28xx.h       |  8 ++++++--
>  6 files changed, 56 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/media/usb/em28xx/em28xx-audio.c b/drivers/media/usb/em28xx/em28xx-audio.c
> index 0f5b6f3e7a3f..f75c0a5494d6 100644
> --- a/drivers/media/usb/em28xx/em28xx-audio.c
> +++ b/drivers/media/usb/em28xx/em28xx-audio.c
> @@ -301,6 +301,7 @@ static int snd_em28xx_capture_open(struct snd_pcm_substream *substream)
>  			goto err;
>  	}
>  
> +	kref_get(&dev->ref);
>  	dev->adev.users++;
>  	mutex_unlock(&dev->lock);
>  
> @@ -341,6 +342,7 @@ static int snd_em28xx_pcm_close(struct snd_pcm_substream *substream)
>  		substream->runtime->dma_area = NULL;
>  	}
>  	mutex_unlock(&dev->lock);
> +	kref_put(&dev->ref, em28xx_free_device);
>  
>  	return 0;
>  }
> @@ -895,6 +897,8 @@ static int em28xx_audio_init(struct em28xx *dev)
>  
>  	em28xx_info("Binding audio extension\n");
>  
> +	kref_get(&dev->ref);
> +
>  	printk(KERN_INFO "em28xx-audio.c: Copyright (C) 2006 Markus "
>  			 "Rechberger\n");
>  	printk(KERN_INFO
> @@ -967,7 +971,7 @@ static int em28xx_audio_fini(struct em28xx *dev)
>  	if (dev == NULL)
>  		return 0;
>  
> -	if (dev->has_alsa_audio != 1) {
> +	if (!dev->has_alsa_audio) {
>  		/* This device does not support the extension (in this case
>  		   the device is expecting the snd-usb-audio module or
>  		   doesn't have analog audio support at all) */
> @@ -986,6 +990,7 @@ static int em28xx_audio_fini(struct em28xx *dev)
>  		dev->adev.sndcard = NULL;
>  	}
>  
> +	kref_put(&dev->ref, em28xx_free_device);
>  	return 0;
>  }
>  
> diff --git a/drivers/media/usb/em28xx/em28xx-cards.c b/drivers/media/usb/em28xx/em28xx-cards.c
> index 2fb300e882f0..015e3731a1c0 100644
> --- a/drivers/media/usb/em28xx/em28xx-cards.c
> +++ b/drivers/media/usb/em28xx/em28xx-cards.c
> @@ -2939,7 +2939,7 @@ static void flush_request_modules(struct em28xx *dev)
>   * unregisters the v4l2,i2c and usb devices
>   * called when the device gets disconnected or at module unload
>  */
> -void em28xx_release_resources(struct em28xx *dev)
> +static void em28xx_release_resources(struct em28xx *dev)
>  {
>  	/*FIXME: I2C IR should be disconnected */
>  
> @@ -2956,7 +2956,27 @@ void em28xx_release_resources(struct em28xx *dev)
>  
>  	mutex_unlock(&dev->lock);
>  };
> -EXPORT_SYMBOL_GPL(em28xx_release_resources);
> +
> +/**
> + * em28xx_free_defice() - Free em28xx device
Small typo. ;-)

Reviewed-by: Frank Schäfer <fschaefer.oss@googlemail.com>

> + *
> + * @ref: struct kref for em28xx device
> + *
> + * This is called when all extensions and em28xx core unregisters a device
> + */
> +void em28xx_free_device(struct kref *ref)
> +{
> +	struct em28xx *dev = kref_to_dev(ref);
> +
> +	em28xx_info("Freeing device\n");
> +
> +	if (!dev->disconnected)
> +		em28xx_release_resources(dev);
> +
> +	kfree(dev->alt_max_pkt_size_isoc);
> +	kfree(dev);
> +}
> +EXPORT_SYMBOL_GPL(em28xx_free_device);
>  
>  /*
>   * em28xx_init_dev()
> @@ -3409,6 +3429,8 @@ static int em28xx_usb_probe(struct usb_interface *interface,
>  			    dev->dvb_xfer_bulk ? "bulk" : "isoc");
>  	}
>  
> +	kref_init(&dev->ref);
> +
>  	request_modules(dev);
>  
>  	/* Should be the last thing to do, to avoid newer udev's to
> @@ -3453,11 +3475,7 @@ static void em28xx_usb_disconnect(struct usb_interface *interface)
>  	em28xx_close_extension(dev);
>  
>  	em28xx_release_resources(dev);
> -
> -	if (!dev->users) {
> -		kfree(dev->alt_max_pkt_size_isoc);
> -		kfree(dev);
> -	}
> +	kref_put(&dev->ref, em28xx_free_device);
>  }
>  
>  static int em28xx_usb_suspend(struct usb_interface *interface,
> diff --git a/drivers/media/usb/em28xx/em28xx-dvb.c b/drivers/media/usb/em28xx/em28xx-dvb.c
> index d4986bdfbdc3..cacdca3a3412 100644
> --- a/drivers/media/usb/em28xx/em28xx-dvb.c
> +++ b/drivers/media/usb/em28xx/em28xx-dvb.c
> @@ -1043,7 +1043,6 @@ static int em28xx_dvb_init(struct em28xx *dev)
>  	em28xx_info("Binding DVB extension\n");
>  
>  	dvb = kzalloc(sizeof(struct em28xx_dvb), GFP_KERNEL);
> -
>  	if (dvb == NULL) {
>  		em28xx_info("em28xx_dvb: memory allocation failed\n");
>  		return -ENOMEM;
> @@ -1521,6 +1520,9 @@ static int em28xx_dvb_init(struct em28xx *dev)
>  	dvb->adapter.mfe_shared = mfe_shared;
>  
>  	em28xx_info("DVB extension successfully initialized\n");
> +
> +	kref_get(&dev->ref);
> +
>  ret:
>  	em28xx_set_mode(dev, EM28XX_SUSPEND);
>  	mutex_unlock(&dev->lock);
> @@ -1577,6 +1579,7 @@ static int em28xx_dvb_fini(struct em28xx *dev)
>  		em28xx_unregister_dvb(dvb);
>  		kfree(dvb);
>  		dev->dvb = NULL;
> +		kref_put(&dev->ref, em28xx_free_device);
>  	}
>  
>  	return 0;
> diff --git a/drivers/media/usb/em28xx/em28xx-input.c b/drivers/media/usb/em28xx/em28xx-input.c
> index 47a2c1dcccbf..2a9bf667f208 100644
> --- a/drivers/media/usb/em28xx/em28xx-input.c
> +++ b/drivers/media/usb/em28xx/em28xx-input.c
> @@ -676,6 +676,8 @@ static int em28xx_ir_init(struct em28xx *dev)
>  		return 0;
>  	}
>  
> +	kref_get(&dev->ref);
> +
>  	if (dev->board.buttons)
>  		em28xx_init_buttons(dev);
>  
> @@ -816,7 +818,7 @@ static int em28xx_ir_fini(struct em28xx *dev)
>  
>  	/* skip detach on non attached boards */
>  	if (!ir)
> -		return 0;
> +		goto ref_put;
>  
>  	if (ir->rc)
>  		rc_unregister_device(ir->rc);
> @@ -824,6 +826,10 @@ static int em28xx_ir_fini(struct em28xx *dev)
>  	/* done */
>  	kfree(ir);
>  	dev->ir = NULL;
> +
> +ref_put:
> +	kref_put(&dev->ref, em28xx_free_device);
> +
>  	return 0;
>  }
>  
> diff --git a/drivers/media/usb/em28xx/em28xx-video.c b/drivers/media/usb/em28xx/em28xx-video.c
> index 19af6b3e9e2b..32aa55f033fc 100644
> --- a/drivers/media/usb/em28xx/em28xx-video.c
> +++ b/drivers/media/usb/em28xx/em28xx-video.c
> @@ -1837,7 +1837,6 @@ static int em28xx_v4l2_open(struct file *filp)
>  			video_device_node_name(vdev), v4l2_type_names[fh_type],
>  			dev->users);
>  
> -
>  	if (mutex_lock_interruptible(&dev->lock))
>  		return -ERESTARTSYS;
>  	fh = kzalloc(sizeof(struct em28xx_fh), GFP_KERNEL);
> @@ -1869,6 +1868,7 @@ static int em28xx_v4l2_open(struct file *filp)
>  		v4l2_device_call_all(&dev->v4l2_dev, 0, tuner, s_radio);
>  	}
>  
> +	kref_get(&dev->ref);
>  	dev->users++;
>  
>  	mutex_unlock(&dev->lock);
> @@ -1926,9 +1926,8 @@ static int em28xx_v4l2_fini(struct em28xx *dev)
>  		dev->clk = NULL;
>  	}
>  
> -	if (dev->users)
> -		em28xx_warn("Device is open ! Memory deallocation is deferred on last close.\n");
>  	mutex_unlock(&dev->lock);
> +	kref_put(&dev->ref, em28xx_free_device);
>  
>  	return 0;
>  }
> @@ -1976,11 +1975,9 @@ static int em28xx_v4l2_close(struct file *filp)
>  	mutex_lock(&dev->lock);
>  
>  	if (dev->users == 1) {
> -		/* free the remaining resources if device is disconnected */
> -		if (dev->disconnected) {
> -			kfree(dev->alt_max_pkt_size_isoc);
> +		/* No sense to try to write to the device */
> +		if (dev->disconnected)
>  			goto exit;
> -		}
>  
>  		/* Save some power by putting tuner to sleep */
>  		v4l2_device_call_all(&dev->v4l2_dev, 0, core, s_power, 0);
> @@ -2001,6 +1998,8 @@ static int em28xx_v4l2_close(struct file *filp)
>  exit:
>  	dev->users--;
>  	mutex_unlock(&dev->lock);
> +	kref_put(&dev->ref, em28xx_free_device);
> +
>  	return 0;
>  }
>  
> @@ -2515,6 +2514,8 @@ static int em28xx_v4l2_init(struct em28xx *dev)
>  
>  	em28xx_info("V4L2 extension successfully initialized\n");
>  
> +	kref_get(&dev->ref);
> +
>  	mutex_unlock(&dev->lock);
>  	return 0;
>  
> diff --git a/drivers/media/usb/em28xx/em28xx.h b/drivers/media/usb/em28xx/em28xx.h
> index 9e44f5bfc48b..2051fc9fb932 100644
> --- a/drivers/media/usb/em28xx/em28xx.h
> +++ b/drivers/media/usb/em28xx/em28xx.h
> @@ -32,6 +32,7 @@
>  #include <linux/workqueue.h>
>  #include <linux/i2c.h>
>  #include <linux/mutex.h>
> +#include <linux/kref.h>
>  #include <linux/videodev2.h>
>  
>  #include <media/videobuf2-vmalloc.h>
> @@ -536,9 +537,10 @@ struct em28xx_i2c_bus {
>  	enum em28xx_i2c_algo_type algo_type;
>  };
>  
> -
>  /* main device struct */
>  struct em28xx {
> +	struct kref ref;
> +
>  	/* generic device properties */
>  	char name[30];		/* name (including minor) of the device */
>  	int model;		/* index in the device_data struct */
> @@ -710,6 +712,8 @@ struct em28xx {
>  	struct em28xx_dvb *dvb;
>  };
>  
> +#define kref_to_dev(d) container_of(d, struct em28xx, ref)
> +
>  struct em28xx_ops {
>  	struct list_head next;
>  	char *name;
> @@ -771,7 +775,7 @@ extern struct em28xx_board em28xx_boards[];
>  extern struct usb_device_id em28xx_id_table[];
>  int em28xx_tuner_callback(void *ptr, int component, int command, int arg);
>  void em28xx_setup_xc3028(struct em28xx *dev, struct xc2028_ctrl *ctl);
> -void em28xx_release_resources(struct em28xx *dev);
> +void em28xx_free_device(struct kref *ref);
>  
>  /* Provided by em28xx-camera.c */
>  int em28xx_detect_sensor(struct em28xx *dev);