staging/easycap: kill telltale logic

This reason for this feature was

'some versions of the videodev module overwrite the data which has
been written by the call to usb_set_intfdata() in easycap_usb_probe(),
replacing it with a pointer to the embedded v4l2_device structure.
to detect this, the string in the easycap.telltale[] buffer is checked.'

The upstream version of v4l2_device_register sets driver data
only when it wasn't already set, therefore this is not needed
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/easycap/easycap.h

@@ -280,8 +280,6 @@ struct inputset {
  */
 /*---------------------------------------------------------------------------*/
 struct easycap {
-#define TELLTALE "expectedstring"
-	char telltale[16];
 	int isdongle;
 	int minor;
 

drivers/staging/easycap/easycap_ioctl.c

@@ -967,10 +967,6 @@ long easycap_unlocked_ioctl(struct file *file,
 		SAY("ERROR:  peasycap is NULL\n");
 		return -1;
 	}
-	if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
-		SAY("ERROR: bad peasycap\n");
-		return -EFAULT;
-	}
 	p = peasycap->pusb_device;
 	if (!p) {
 		SAM("ERROR: peasycap->pusb_device is NULL\n");
@@ -1004,12 +1000,6 @@ long easycap_unlocked_ioctl(struct file *file,
 			mutex_unlock(&easycapdc60_dongle[kd].mutex_video);
 			return -ERESTARTSYS;
 		}
-		if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
-			SAY("ERROR: bad peasycap\n");
-			mutex_unlock(&easycapdc60_dongle[kd].mutex_video);
-			return -EFAULT;
-		}
-		p = peasycap->pusb_device;
 		if (!peasycap->pusb_device) {
 			SAM("ERROR: peasycap->pusb_device is NULL\n");
 			mutex_unlock(&easycapdc60_dongle[kd].mutex_video);

drivers/staging/easycap/easycap_main.c

@@ -158,10 +158,6 @@ static int easycap_open(struct inode *inode, struct file *file)
 		SAY("ERROR: peasycap is NULL\n");
 		return -EFAULT;
 	}
-	if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
-		SAY("ERROR: bad peasycap: %p\n", peasycap);
-		return -EFAULT;
-	}
 	if (!peasycap->pusb_device) {
 		SAM("ERROR: peasycap->pusb_device is NULL\n");
 		return -EFAULT;
@@ -695,10 +691,6 @@ static int videodev_release(struct video_device *pvideo_device)
 		SAY("ending unsuccessfully\n");
 		return -EFAULT;
 	}
-	if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
-		SAY("ERROR: bad peasycap: %p\n", peasycap);
-		return -EFAULT;
-	}
 	if (0 != kill_video_urbs(peasycap)) {
 		SAM("ERROR: kill_video_urbs() failed\n");
 		return -EFAULT;
@@ -736,10 +728,6 @@ static void easycap_delete(struct kref *pkref)
 		SAM("ERROR: peasycap is NULL: cannot perform deletions\n");
 		return;
 	}
-	if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
-		SAY("ERROR: bad peasycap: %p\n", peasycap);
-		return;
-	}
 	kd = isdongle(peasycap);
 /*---------------------------------------------------------------------------*/
 /*
@@ -962,10 +950,6 @@ static unsigned int easycap_poll(struct file *file, poll_table *wait)
 		SAY("ERROR:  peasycap is NULL\n");
 		return -EFAULT;
 	}
-	if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
-		SAY("ERROR: bad peasycap: %p\n", peasycap);
-		return -EFAULT;
-	}
 	if (!peasycap->pusb_device) {
 		SAY("ERROR:  peasycap->pusb_device is NULL\n");
 		return -EFAULT;
@@ -996,11 +980,6 @@ static unsigned int easycap_poll(struct file *file, poll_table *wait)
 			mutex_unlock(&easycapdc60_dongle[kd].mutex_video);
 			return -ERESTARTSYS;
 		}
-		if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
-			SAY("ERROR: bad peasycap: %p\n", peasycap);
-			mutex_unlock(&easycapdc60_dongle[kd].mutex_video);
-			return -ERESTARTSYS;
-		}
 		if (!peasycap->pusb_device) {
 			SAM("ERROR: peasycap->pusb_device is NULL\n");
 			mutex_unlock(&easycapdc60_dongle[kd].mutex_video);
@@ -2455,10 +2434,6 @@ static void easycap_vma_open(struct vm_area_struct *pvma)
 		SAY("ERROR: peasycap is NULL\n");
 		return;
 	}
-	if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
-		SAY("ERROR: bad peasycap: %p\n", peasycap);
-		return;
-	}
 	peasycap->vma_many++;
 	JOT(8, "%i=peasycap->vma_many\n", peasycap->vma_many);
 	return;
@@ -2473,10 +2448,6 @@ static void easycap_vma_close(struct vm_area_struct *pvma)
 		SAY("ERROR: peasycap is NULL\n");
 		return;
 	}
-	if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
-		SAY("ERROR: bad peasycap: %p\n", peasycap);
-		return;
-	}
 	peasycap->vma_many--;
 	JOT(8, "%i=peasycap->vma_many\n", peasycap->vma_many);
 	return;
@@ -2607,10 +2578,6 @@ static void easycap_complete(struct urb *purb)
 		SAY("ERROR: easycap_complete(): peasycap is NULL\n");
 		return;
 	}
-	if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
-		SAY("ERROR: bad peasycap: %p\n", peasycap);
-		return;
-	}
 	if (peasycap->video_eof)
 		return;
 	for (i = 0; i < VIDEO_ISOC_BUFFER_MANY; i++)
@@ -3001,7 +2968,6 @@ static int easycap_usb_probe(struct usb_interface *intf,
 	struct easycap_format *peasycap_format;
 	int fmtidx;
 	struct inputset *inputset;
-	struct v4l2_device *pv4l2_device;
 
 	usbdev = interface_to_usbdev(intf);
 
@@ -3055,7 +3021,6 @@ static int easycap_usb_probe(struct usb_interface *intf,
 */
 /*---------------------------------------------------------------------------*/
 		peasycap->minor = -1;
-		strcpy(&peasycap->telltale[0], TELLTALE);
 		kref_init(&peasycap->kref);
 		JOM(8, "intf[%i]: after kref_init(..._video) "
 				"%i=peasycap->kref.refcount.counter\n",
@@ -3268,23 +3233,6 @@ static int easycap_usb_probe(struct usb_interface *intf,
 								bInterfaceNumber);
 			return -ENODEV;
 		}
-/*---------------------------------------------------------------------------*/
-/*
- *  SOME VERSIONS OF THE videodev MODULE OVERWRITE THE DATA WHICH HAS
- *  BEEN WRITTEN BY THE CALL TO usb_set_intfdata() IN easycap_usb_probe(),
- *  REPLACING IT WITH A POINTER TO THE EMBEDDED v4l2_device STRUCTURE.
- *  TO DETECT THIS, THE STRING IN THE easycap.telltale[] BUFFER IS CHECKED.
-*/
-/*---------------------------------------------------------------------------*/
-		if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
-			pv4l2_device = usb_get_intfdata(intf);
-			if (!pv4l2_device) {
-				SAY("ERROR: pv4l2_device is NULL\n");
-				return -ENODEV;
-			}
-			peasycap = (struct easycap *)
-				container_of(pv4l2_device, struct easycap, v4l2_device);
-		}
 	}
 /*---------------------------------------------------------------------------*/
 	if ((USB_CLASS_VIDEO == bInterfaceClass) ||
@@ -3776,14 +3724,12 @@ static int easycap_usb_probe(struct usb_interface *intf,
  *  THE VIDEO DEVICE CAN BE REGISTERED NOW, AS IT IS READY.
  */
 /*--------------------------------------------------------------------------*/
-		if (0 != (v4l2_device_register(&(intf->dev),
-							&(peasycap->v4l2_device)))) {
+		if (v4l2_device_register(&intf->dev, &peasycap->v4l2_device)) {
 			SAM("v4l2_device_register() failed\n");
 			return -ENODEV;
-		} else {
-			JOM(4, "registered device instance: %s\n",
-						&(peasycap->v4l2_device.name[0]));
 		}
+		JOM(4, "registered device instance: %s\n",
+			peasycap->v4l2_device.name);
 /*---------------------------------------------------------------------------*/
 /*
  *                                 FIXME
@@ -4160,7 +4106,6 @@ static void easycap_usb_disconnect(struct usb_interface *pusb_interface)
 	struct list_head *plist_head;
 	struct data_urb *pdata_urb;
 	int minor, m, kd;
-	struct v4l2_device *pv4l2_device;
 
 	JOT(4, "\n");
 
@@ -4187,29 +4132,6 @@ static void easycap_usb_disconnect(struct usb_interface *pusb_interface)
 		return;
 	}
 /*---------------------------------------------------------------------------*/
-/*
- *  SOME VERSIONS OF THE videodev MODULE OVERWRITE THE DATA WHICH HAS
- *  BEEN WRITTEN BY THE CALL TO usb_set_intfdata() IN easycap_usb_probe(),
- *  REPLACING IT WITH A POINTER TO THE EMBEDDED v4l2_device STRUCTURE.
- *  TO DETECT THIS, THE STRING IN THE easycap.telltale[] BUFFER IS CHECKED.
-*/
-/*---------------------------------------------------------------------------*/
-	if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
-		pv4l2_device = usb_get_intfdata(pusb_interface);
-		if (!pv4l2_device) {
-			SAY("ERROR: pv4l2_device is NULL\n");
-			return;
-		}
-		peasycap = (struct easycap *)
-			container_of(pv4l2_device, struct easycap, v4l2_device);
-	}
-/*^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^*/
-/*---------------------------------------------------------------------------*/
-	if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
-		SAY("ERROR: bad peasycap: %p\n", peasycap);
-		return;
-	}
-/*---------------------------------------------------------------------------*/
 /*
  *  IF THE WAIT QUEUES ARE NOT CLEARED A DEADLOCK IS POSSIBLE.  BEWARE.
 */

drivers/staging/easycap/easycap_sound.c

@@ -92,10 +92,6 @@ easycap_alsa_complete(struct urb *purb)
 		SAY("ERROR: peasycap is NULL\n");
 		return;
 	}
-	if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
-		SAY("ERROR: bad peasycap\n");
-		return;
-	}
 	much = 0;
 	if (peasycap->audio_idle) {
 		JOM(16, "%i=audio_idle  %i=audio_isoc_streaming\n",
@@ -310,10 +306,6 @@ static int easycap_alsa_open(struct snd_pcm_substream *pss)
 		SAY("ERROR:  peasycap is NULL\n");
 		return -EFAULT;
 	}
-	if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
-		SAY("ERROR: bad peasycap\n");
-		return -EFAULT;
-	}
 	if (peasycap->psnd_card != psnd_card) {
 		SAM("ERROR: bad peasycap->psnd_card\n");
 		return -EFAULT;
@@ -350,10 +342,6 @@ static int easycap_alsa_close(struct snd_pcm_substream *pss)
 		SAY("ERROR:  peasycap is NULL\n");
 		return -EFAULT;
 	}
-	if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
-		SAY("ERROR: bad peasycap\n");
-		return -EFAULT;
-	}
 	pss->private_data = NULL;
 	peasycap->psubstream = NULL;
 	JOT(4, "ending successfully\n");
@@ -441,10 +429,6 @@ static int easycap_alsa_prepare(struct snd_pcm_substream *pss)
 		SAY("ERROR:  peasycap is NULL\n");
 		return -EFAULT;
 	}
-	if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
-		SAY("ERROR: bad peasycap\n");
-		return -EFAULT;
-	}
 
 	JOM(16, "ALSA decides %8i Hz=rate\n", pss->runtime->rate);
 	JOM(16, "ALSA decides %8ld =period_size\n", pss->runtime->period_size);
@@ -488,11 +472,6 @@ static int easycap_alsa_trigger(struct snd_pcm_substream *pss, int cmd)
 		SAY("ERROR:  peasycap is NULL\n");
 		return -EFAULT;
 	}
-	if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
-		SAY("ERROR: bad peasycap\n");
-		return -EFAULT;
-	}
-
 	switch (cmd) {
 	case SNDRV_PCM_TRIGGER_START: {
 		peasycap->audio_idle = 0;
@@ -523,10 +502,6 @@ static snd_pcm_uframes_t easycap_alsa_pointer(struct snd_pcm_substream *pss)
 		SAY("ERROR:  peasycap is NULL\n");
 		return -EFAULT;
 	}
-	if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
-		SAY("ERROR: bad peasycap\n");
-		return -EFAULT;
-	}
 	if ((0 != peasycap->audio_eof) || (0 != peasycap->audio_idle)) {
 		JOM(8, "returning -EIO because  "
 		    "%i=audio_idle  %i=audio_eof\n",
@@ -584,10 +559,6 @@ int easycap_alsa_probe(struct easycap *peasycap)
 		SAY("ERROR: peasycap is NULL\n");
 		return -ENODEV;
 	}
-	if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
-		SAY("ERROR: bad peasycap\n");
-		return -EFAULT;
-	}
 	if (0 > peasycap->minor) {
 		SAY("ERROR: no minor\n");
 		return -ENODEV;