[patch 07/25] Close race in md_probe

Greg KH
2008-08-04T21:37:39Z

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2.6.26-stable review patch. If anyone has any objections, please let us
know.

------------------

From: Neil Brown <neilb@suse.de>

[ Upstream commit f48ed538386cb41559282d989354e8f5d442d71c ]

There is a possible race in md_probe. If two threads call md_probe
for the same device, then one could exit (having checked that
->gendisk exists) before the other has called kobject_init_and_add,
thus returning an incomplete kobj which will cause problems when
we try to add children to it.

So extend the range of protection of disks_mutex slightly to
avoid this possibility.

Signed-off-by: Neil Brown <neilb@suse.de>
CC: Oliver Pinter <oliver.pntr@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/md/md.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -3326,9 +3326,9 @@ static struct kobject *md_probe(dev_t de
disk->queue = mddev->queue;
add_disk(disk);
mddev->gendisk = disk;
- mutex_unlock(&disks_mutex);
error = kobject_init_and_add(&mddev->kobj, &md_ktype, &disk->dev.kobj,
"%s", "md");
+ mutex_unlock(&disks_mutex);
if (error)
printk(KERN_WARNING "md: cannot register %s/md - name in use\n",
disk->disk_name);

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