V4L/DVB (4316): Check __must_check warnings

Check __must_check warnings for class_device_register and class_device_create_file

video_device_create_file was declared as a void, but instead should
return the int value of class_device_create_file.

Move the check from bttv-driver.c into v4l2-dev.h, because all other
callers of video_device_create_file must also be checked.

Replace the call to class_device_create_file in videodev.c with
video_device_create_file, as defined in v4l2-dev.h, so that the
return value of class_device_create_file will be checked.

Check the return value of class_device_register in videodev.c and
pvrusb2-sysfs.c

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

drivers/media/video/bt8xx/bttv-driver.c

@@ -3909,8 +3909,6 @@ static void bttv_unregister_video(struct bttv *btv)
 /* register video4linux devices */
 static int __devinit bttv_register_video(struct bttv *btv)
 {
-	int ret;
-
 	if (no_overlay <= 0) {
 		bttv_video_template.type |= VID_TYPE_OVERLAY;
 	} else {
@@ -3925,10 +3923,8 @@ static int __devinit bttv_register_video(struct bttv *btv)
 		goto err;
 	printk(KERN_INFO "bttv%d: registered device video%d\n",
 	       btv->c.nr,btv->video_dev->minor & 0x1f);
-	ret = video_device_create_file(btv->video_dev, &class_device_attr_card);
-	if (ret < 0)
-		printk(KERN_WARNING "bttv: video_device_create_file error: "
-			"%d\n", ret);
+
+	video_device_create_file(btv->video_dev, &class_device_attr_card);
 
 	/* vbi */
 	btv->vbi_dev = vdev_init(btv, &bttv_vbi_template, "vbi");

drivers/media/video/pvrusb2/pvrusb2-sysfs.c

@@ -600,6 +600,8 @@ static ssize_t debugcmd_store(struct class_device *,const char *,size_t count);
 static void pvr2_sysfs_add_debugifc(struct pvr2_sysfs *sfp)
 {
 	struct pvr2_sysfs_debugifc *dip;
+	int ret;
+
 	dip = kmalloc(sizeof(*dip),GFP_KERNEL);
 	if (!dip) return;
 	memset(dip,0,sizeof(*dip));
@@ -613,8 +615,14 @@ static void pvr2_sysfs_add_debugifc(struct pvr2_sysfs *sfp)
 	dip->attr_debuginfo.attr.mode = S_IRUGO;
 	dip->attr_debuginfo.show = debuginfo_show;
 	sfp->debugifc = dip;
-	class_device_create_file(sfp->class_dev,&dip->attr_debugcmd);
-	class_device_create_file(sfp->class_dev,&dip->attr_debuginfo);
+	ret = class_device_create_file(sfp->class_dev,&dip->attr_debugcmd);
+	if (ret < 0)
+		printk(KERN_WARNING "%s: class_device_create_file error: %d\n",
+		       __FUNCTION__, ret);
+	ret = class_device_create_file(sfp->class_dev,&dip->attr_debuginfo);
+	if (ret < 0)
+		printk(KERN_WARNING "%s: class_device_create_file error: %d\n",
+		       __FUNCTION__, ret);
 }
 
 
@@ -709,6 +717,8 @@ static void class_dev_create(struct pvr2_sysfs *sfp,
 {
 	struct usb_device *usb_dev;
 	struct class_device *class_dev;
+	int ret;
+
 	usb_dev = pvr2_hdw_get_dev(sfp->channel.hdw);
 	if (!usb_dev) return;
 	class_dev = kmalloc(sizeof(*class_dev),GFP_KERNEL);
@@ -733,20 +743,33 @@ static void class_dev_create(struct pvr2_sysfs *sfp,
 
 	sfp->class_dev = class_dev;
 	class_dev->class_data = sfp;
-	class_device_register(class_dev);
+	ret = class_device_register(class_dev);
+	if (ret) {
+		printk(KERN_ERR "%s: class_device_register failed\n",
+		       __FUNCTION__);
+		kfree(class_dev);
+		return;
+	}
 
 	sfp->attr_v4l_minor_number.attr.owner = THIS_MODULE;
 	sfp->attr_v4l_minor_number.attr.name = "v4l_minor_number";
 	sfp->attr_v4l_minor_number.attr.mode = S_IRUGO;
 	sfp->attr_v4l_minor_number.show = v4l_minor_number_show;
 	sfp->attr_v4l_minor_number.store = NULL;
-	class_device_create_file(sfp->class_dev,&sfp->attr_v4l_minor_number);
+	ret = class_device_create_file(sfp->class_dev,&sfp->attr_v4l_minor_number);
+	if (ret < 0)
+		printk(KERN_WARNING "%s: class_device_create_file error: %d\n",
+		       __FUNCTION__, ret);
+
 	sfp->attr_unit_number.attr.owner = THIS_MODULE;
 	sfp->attr_unit_number.attr.name = "unit_number";
 	sfp->attr_unit_number.attr.mode = S_IRUGO;
 	sfp->attr_unit_number.show = unit_number_show;
 	sfp->attr_unit_number.store = NULL;
-	class_device_create_file(sfp->class_dev,&sfp->attr_unit_number);
+	ret = class_device_create_file(sfp->class_dev,&sfp->attr_unit_number);
+	if (ret < 0)
+		printk(KERN_WARNING "%s: class_device_create_file error: %d\n",
+		       __FUNCTION__, ret);
 
 	pvr2_sysfs_add_controls(sfp);
 #ifdef CONFIG_VIDEO_PVRUSB2_DEBUGIFC

drivers/media/video/videodev.c

@@ -1512,6 +1512,7 @@ int video_register_device(struct video_device *vfd, int type, int nr)
 	int i=0;
 	int base;
 	int end;
+	int ret;
 	char *name_base;
 
 	switch(type)
@@ -1571,9 +1572,13 @@ int video_register_device(struct video_device *vfd, int type, int nr)
 	vfd->class_dev.class       = &video_class;
 	vfd->class_dev.devt        = MKDEV(VIDEO_MAJOR, vfd->minor);
 	sprintf(vfd->class_dev.class_id, "%s%d", name_base, i - base);
-	class_device_register(&vfd->class_dev);
-	class_device_create_file(&vfd->class_dev,
-				&class_device_attr_name);
+	ret = class_device_register(&vfd->class_dev);
+	if (ret) {
+		printk(KERN_ERR "%s: class_device_register failed\n",
+		       __FUNCTION__);
+		return ret;
+	}
+	video_device_create_file(vfd, &class_device_attr_name);
 
 #if 1
 	/* needed until all drivers are fixed */

include/media/v4l2-dev.h

@@ -341,11 +341,14 @@ extern int video_usercopy(struct inode *inode, struct file *file,
 extern struct video_device* video_devdata(struct file*);
 
 #define to_video_device(cd) container_of(cd, struct video_device, class_dev)
-static inline void
+static inline int
 video_device_create_file(struct video_device *vfd,
 			 struct class_device_attribute *attr)
 {
-	class_device_create_file(&vfd->class_dev, attr);
+	int ret = class_device_create_file(&vfd->class_dev, attr);
+	if (ret < 0)
+		printk(KERN_WARNING "%s error: %d\n", __FUNCTION__, ret);
+	return ret;
 }
 static inline void
 video_device_remove_file(struct video_device *vfd,