Hi Tejun,

Below are the tests I performed:
Test1:
a) Power off the drive
b) echo "scsi remove-single-device h b t l" > /proc/scsi/scsi
or delete using sysfs
c) Power on the drive
d) echo "scsi add-single-device h b t l" > /proc/scsi/scsi
or scan using sysfs
The kernel error in my first email is induced in this test but not
consistently reproducible. In most of the case, no kernel error but sg
was not reattached when adding device.

Test2:
Ignore step c) in test1. Basically, try to add device while the device
is still powered off.

Hope this helps.

Thanks,
Fajun

On 8/25/06, Tejun Heo [off-list ref] wrote:

Fajun Chen wrote:

quoted

Hi Tejun,

JFYI. I found a workaround which seems to be working in 2.6.18-rc2.
During warm plug/unplug, if I don't delete the device through sysfs or
proc and just rescan the host, it recovered just fine.

Hello,

I'm trying to reproduce it here but haven't succeeded yet.  Can you
describe what you did in more detail?  I'm trying various things -
issuing delete / scan, combination of them after unplugging my drive,
etc..., but haven't succeeded in reproducing your error condition.  It
seems to be a sdev refcnting problem in libata but I need more clue...

Thanks.

--
tejun