Alternative fix for MMC oops on unmount after removal

Make sure to clear the driverfs_dev pointer when we do del_gendisk() (on
disk removal), so that other users that may still have a ref to the disk
won't try to use the stale pointer.

Also move the KOBJ_REMOVE uevent handler up, so that the uevent still
has access to the driverfs_dev data.

This all should hopefully fix the problems with MMC umounts after device
removals that caused commit 56cf6504fc1c0c221b82cebc16a444b684140fb7 and
its reversal (1a2acc9e9214699a99389e323e6686e9e0e2ca67).

Original problem reported by Todd Blumer and others.

Acked-by: Greg KH <gregkh@suse.de>
Cc: Russell King <rmk+lkml@arm.linux.org.uk>
Cc: James Bottomley <James.Bottomley@SteelEye.com>
Cc: Erik Mouw <erik@harddisk-recovery.com>
Cc: Andrew Vasquez <andrew.vasquez@qlogic.com>
Cc: Todd Blumer <todd@sdgsystems.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/fs/partitions/check.c b/fs/partitions/check.c
index 45ae7dd3c650..7ef1f094de91 100644
--- a/fs/partitions/check.c
+++ b/fs/partitions/check.c
@@ -533,6 +533,7 @@ void del_gendisk(struct gendisk *disk)
 
         devfs_remove_disk(disk);
 
+        kobject_uevent(&disk->kobj, KOBJ_REMOVE);
         if (disk->holder_dir)
                 kobject_unregister(disk->holder_dir);
         if (disk->slave_dir)
@@ -545,7 +546,7 @@ void del_gendisk(struct gendisk *disk)
                         kfree(disk_name);
                 }
                 put_device(disk->driverfs_dev);
+                disk->driverfs_dev = NULL;
         }
-        kobject_uevent(&disk->kobj, KOBJ_REMOVE);
         kobject_del(&disk->kobj);
 }