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[PATCH] md: avoid a deadlock when removing a device from an md array via sysfs

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A device can be removed from an md array via e.g.
  echo remove > /sys/block/md3/md/dev-sde/state

This will try to remove the 'dev-sde' subtree which will deadlock
since
  commit e7b0d26a86

With this patch we run the kobject_del via schedule_work so as to
avoid the deadlock.

Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
NeilBrown 2007-04-04 19:08:18 -07:00 committed by Linus Torvalds
parent 456a09dce9
commit 5792a2856a
2 changed files with 16 additions and 1 deletions
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16
drivers/md/md.c
View file

@ -1378,6 +1378,12 @@ static int bind_rdev_to_array(mdk_rdev_t * rdev, mddev_t * mddev)
return err;
}
static void delayed_delete(struct work_struct *ws)
{
mdk_rdev_t *rdev = container_of(ws, mdk_rdev_t, del_work);
kobject_del(&rdev->kobj);
}
static void unbind_rdev_from_array(mdk_rdev_t * rdev)
{
char b[BDEVNAME_SIZE];
@ -1390,7 +1396,12 @@ static void unbind_rdev_from_array(mdk_rdev_t * rdev)
printk(KERN_INFO "md: unbind<%s>\n", bdevname(rdev->bdev,b));
rdev->mddev = NULL;
sysfs_remove_link(&rdev->kobj, "block");
kobject_del(&rdev->kobj);
/* We need to delay this, otherwise we can deadlock when
* writing to 'remove' to "dev/state"
*/
INIT_WORK(&rdev->del_work, delayed_delete);
schedule_work(&rdev->del_work);
}
/*
@ -3389,6 +3400,9 @@ static int do_md_stop(mddev_t * mddev, int mode)
sysfs_remove_link(&mddev->kobj, nm);
}
/* make sure all delayed_delete calls have finished */
flush_scheduled_work();
export_array(mddev);
mddev->array_size = 0;

1
include/linux/raid/md_k.h
View file

@ -104,6 +104,7 @@ struct mdk_rdev_s
* for reporting to userspace and storing
* in superblock.
*/
struct work_struct del_work; /* used for delayed sysfs removal */
};
struct mddev_s