Luben Tuikov [off-list ref] wrote:

On 08/19/05 15:38, Patrick Mansfield wrote:
The eh_timed_out + eh_strategy_handler is actually pretty perfect,
and _complete_, for any application and purpose in recovering a
LU/device/host (in that order ;-) ).

quoted

The two problems I see with the hook are:

It calls the driver in interrupt context, so the called function can't
sleep.

Consider this: When SCSI Core told you that the command timed out,
	A) it has already finished,
	B) it hasn't already finished.

In case A, you can return EH_HANDLED.  In case B, you return
EH_NOT_HANDLED, and deal with it in the eh_strategy_handler.
(Hint: you can still "finish" it from there.)

But dealing with it in the eh_strategy_handler means that you may be
stopping all IO on the host instance as the first lun returns
EH_NOT_HANDLED for LUN based canceling.

I still think we can do better here for an LLDD that cannot execute a
cancel in interrupt context.

Having a error handler that works is a plus, I would hope that
some factoring would happen over time from the eh_strategy_handler to
some transport (or other factor point) error handler. I would think from a
testing, support, and block level multipath predictability sharing code
would be a good goal.

-andmike
--
Michael Anderson
andmike@us.ibm.com