Re: [PATCH v3 1/2] Ensure that the SCSI error handler gets woken up

[Stuart Hayes <stuart.w.hayes@gmail.com>]

>>>> In case (a) scsi_eh_inc_host_failed() will wake up the error handler. And in
>>>> case (b) scsi_dec_host_busy() will wake up the error handler. So it's not
>>>> clear to me why you think that there is a scenario in which the EH won't be
>>>> woken up?
>>>
>>> So in case (b), in my understanding, scsi_dec_host_busy can skip wakeups
>>> as it does not see host_failed change yet.
>>
>> That's not correct. If scsi_dec_host_busy() obtains the SCSI host lock before
>> scsi_eh_inc_host_failed() obtains it then the latter function will trigger a
>> SCSI EH wakeup.
> 
> You are right! Thanks a lot for pointing that out! Now when I understand it, your patch looks good for me:
> 
> Reviewed-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
> 
> By the way, I very much like your idea of using rcu for these case.
> 
> Thanks, Pavel.
> 

This patch tests ok on my system, too... it's run for over 24 hours, on a system that typically fails within ten minutes without the patch...

Tested-by: Stuart Hayes <stuart.w.hayes@gmail.com>

Thanks,
Stuart


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