From: Anton Vorontsov <cbou@mail.ru>

No need to get_device(driverfs_dev), because it's already gotten by
add_disk(). And no function will call put_device() second time.
This is the source of deadlock[1] in IDE layer. SCSI workaround it by
calling put_device() themself after put_disk(), thus it should reflect
this change by removing put_device().

[1] deadlock in ide_unregister()
at wait_for_completion(&drive->gendev_rel_comp) after
device_unregister(&drive->gendev). That happens by reason of
ide-probe.c:drive_release_dev() not called because of driverfs_dev
(which is drive->gendev) still referenced by add_disk().

Index: fs/partitions/check.c
===================================================================
RCS file: /cvs/linux/kernel26/fs/partitions/check.c,v
retrieving revision 1.17
diff -u -p -b -B -r1.17 check.c
--- fs/partitions/check.c	23 Aug 2006 18:40:39 -0000	1.17
+++ fs/partitions/check.c	18 Oct 2006 21:13:26 -0000
@@ -389,7 +389,7 @@ static char *make_block_name(struct gend
 
 static void disk_sysfs_symlinks(struct gendisk *disk)
 {
-	struct device *target = get_device(disk->driverfs_dev);
+	struct device *target = disk->driverfs_dev;
 	if (target) {
 		char *disk_name = make_block_name(disk);
 		sysfs_create_link(&disk->kobj,&target->kobj,"device");
Index: drivers/scsi/sd.c
===================================================================
RCS file: /cvs/linux/kernel26/drivers/scsi/sd.c,v
retrieving revision 1.18
diff -u -p -b -B -r1.18 sd.c
--- drivers/scsi/sd.c	23 Aug 2006 18:38:06 -0000	1.18
+++ drivers/scsi/sd.c	18 Oct 2006 21:14:54 -0000
@@ -1756,7 +1756,6 @@ static void scsi_disk_release(struct cla
 
 	disk->private_data = NULL;
 	put_disk(disk);
-	put_device(&sdkp->device->sdev_gendev);
 
 	kfree(sdkp);
 }