V4L/DVB (5630): Dvb-core: Handle failures to create devices

dvb-core is not started early enough when device drivers that use dvb are
compiled in so dvb_register_device fails (silently) since dvb_class is
NULL, this runs dvb_init using subsys_initcall instead of module_init.

dvb_register_device will now check the return value of class_device_create.
Signed-off-by: Simon Arlott <simon@fire.lp0.eu>
Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

drivers/media/dvb/dvb-core/dvbdev.c

@@ -200,7 +200,7 @@ int dvb_register_device(struct dvb_adapter *adap, struct dvb_device **pdvbdev,
 {
 	struct dvb_device *dvbdev;
 	struct file_operations *dvbdevfops;
-
+	struct class_device *clsdev;
 	int id;
 
 	mutex_lock(&dvbdev_register_lock);
@@ -242,8 +242,15 @@ int dvb_register_device(struct dvb_adapter *adap, struct dvb_device **pdvbdev,
 
 	mutex_unlock(&dvbdev_register_lock);
 
-	class_device_create(dvb_class, NULL, MKDEV(DVB_MAJOR, nums2minor(adap->num, type, id)),
-			    adap->device, "dvb%d.%s%d", adap->num, dnames[type], id);
+	clsdev = class_device_create(dvb_class, NULL, MKDEV(DVB_MAJOR,
+				     nums2minor(adap->num, type, id)),
+				     adap->device, "dvb%d.%s%d", adap->num,
+				     dnames[type], id);
+	if (IS_ERR(clsdev)) {
+		printk(KERN_ERR "%s: failed to create device dvb%d.%s%d (%ld)\n",
+		       __FUNCTION__, adap->num, dnames[type], id, PTR_ERR(clsdev));
+		return PTR_ERR(clsdev);
+	}
 
 	dprintk("DVB: register adapter%d/%s%d @ minor: %i (0x%02x)\n",
 		adap->num, dnames[type], id, nums2minor(adap->num, type, id),
@@ -431,7 +438,7 @@ static void __exit exit_dvbdev(void)
 	unregister_chrdev_region(MKDEV(DVB_MAJOR, 0), MAX_DVB_MINORS);
 }
 
-module_init(init_dvbdev);
+subsys_initcall(init_dvbdev);
 module_exit(exit_dvbdev);
 
 MODULE_DESCRIPTION("DVB Core Driver");