ide: fix refcounting in device drivers

During host driver module removal del_gendisk() results in a final
put on drive->gendev and freeing the drive by drive_release_dev().

Convert device drivers from using struct kref to use struct device
so device driver's object holds reference on ->gendev and prevents
drive from prematurely going away.

Also fix ->remove methods to not erroneously drop reference on a
host driver by using only put_device() instead of ide*_put().

Reported-by: Stanislaw Gruszka <stf_xl@wp.pl>
Tested-by: Stanislaw Gruszka <stf_xl@wp.pl>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

drivers/ide/ide-cd.c

@@ -55,7 +55,7 @@
 
 static DEFINE_MUTEX(idecd_ref_mutex);
 
-static void ide_cd_release(struct kref *);
+static void ide_cd_release(struct device *);
 
 static struct cdrom_info *ide_cd_get(struct gendisk *disk)
 {
@@ -67,7 +67,7 @@ static struct cdrom_info *ide_cd_get(struct gendisk *disk)
 		if (ide_device_get(cd->drive))
 			cd = NULL;
 		else
-			kref_get(&cd->kref);
+			get_device(&cd->dev);
 
 	}
 	mutex_unlock(&idecd_ref_mutex);
@@ -79,7 +79,7 @@ static void ide_cd_put(struct cdrom_info *cd)
 	ide_drive_t *drive = cd->drive;
 
 	mutex_lock(&idecd_ref_mutex);
-	kref_put(&cd->kref, ide_cd_release);
+	put_device(&cd->dev);
 	ide_device_put(drive);
 	mutex_unlock(&idecd_ref_mutex);
 }
@@ -1798,15 +1798,17 @@ static void ide_cd_remove(ide_drive_t *drive)
 	ide_debug_log(IDE_DBG_FUNC, "Call %s\n", __func__);
 
 	ide_proc_unregister_driver(drive, info->driver);
-
+	device_del(&info->dev);
 	del_gendisk(info->disk);
 
-	ide_cd_put(info);
+	mutex_lock(&idecd_ref_mutex);
+	put_device(&info->dev);
+	mutex_unlock(&idecd_ref_mutex);
 }
 
-static void ide_cd_release(struct kref *kref)
+static void ide_cd_release(struct device *dev)
 {
-	struct cdrom_info *info = to_ide_drv(kref, cdrom_info);
+	struct cdrom_info *info = to_ide_drv(dev, cdrom_info);
 	struct cdrom_device_info *devinfo = &info->devinfo;
 	ide_drive_t *drive = info->drive;
 	struct gendisk *g = info->disk;
@@ -2005,7 +2007,12 @@ static int ide_cd_probe(ide_drive_t *drive)
 
 	ide_init_disk(g, drive);
 
-	kref_init(&info->kref);
+	info->dev.parent = &drive->gendev;
+	info->dev.release = ide_cd_release;
+	dev_set_name(&info->dev, dev_name(&drive->gendev));
+
+	if (device_register(&info->dev))
+		goto out_free_disk;
 
 	info->drive = drive;
 	info->driver = &ide_cdrom_driver;
@@ -2019,7 +2026,7 @@ static int ide_cd_probe(ide_drive_t *drive)
 	g->driverfs_dev = &drive->gendev;
 	g->flags = GENHD_FL_CD | GENHD_FL_REMOVABLE;
 	if (ide_cdrom_setup(drive)) {
-		ide_cd_release(&info->kref);
+		put_device(&info->dev);
 		goto failed;
 	}
 
@@ -2029,6 +2036,8 @@ static int ide_cd_probe(ide_drive_t *drive)
 	add_disk(g);
 	return 0;
 
+out_free_disk:
+	put_disk(g);
 out_free_cd:
 	kfree(info);
 failed: