Re: [PATCH] sd: use async_probe cookie to avoid deadlocks

Hannes Reinecke
2017-03-21T15:32:41Z

On 03/21/2017 02:33 PM, James Bottomley wrote:
> On Tue, 2017-03-21 at 13:30 +0000, Bart Van Assche wrote:
>> On Tue, 2017-03-21 at 09:05 -0400, James Bottomley wrote:
>>> How does this preserve ordering? It looks like you have one cookie
>>> per sdkp ... is there some sort of ordering guarantee I'm not
>>> seeing?
>>
>> Hello James,
>>
>> Since the probe order depends on the order in which __async_probe()
>> adds entries to the "pending" list, and since the order of the
>> __async_probe() calls is not changed by this patch, shouldn't the
>> probe order be preserved by this patch?
>
> I don't know: that's what I'm asking. I believe they complete in order
> for a single domain. I thought ordering isn't preserved between
> domains? So moving to multiple domains loses us ordering of disk
> appearance.
>
Ah.
But we don't move to multiple domains, now do we?
We're just terminating the wait until _our_ probe is completed.
It's not that we're having a individual probe domain per device...

Unless I'm misunderstanding something...

Cheers,

Hannes
--
Dr. Hannes Reinecke zSeries & Storage
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