Re: [RFC PATCH v2 00/18] scsi: scsi_error: Introduce new error handle mechanism

[Hannes Reinecke]

On 9/26/23 09:26, Christoph Hellwig wrote:
> On Mon, Sep 25, 2023 at 12:54:48PM -0500, Mike Christie wrote:
> > I think we want to figure out Hannes's patches first.
>
> Yes.
>
> > For a new EH design we will want to be able to do multiple TMFs in parallel
> > on the same host/target right?
> >
> > The problem is that we need to be able to make forward progress in the EH
> > path and not fail just because we can't allocate memory for a TMF related
> > struct. To accomplish this now, drivers will use mempools, preallocate TMF
> > related structs/mem/tags with their scsi_cmnd related structs, preallocate
> > per host/target/device related structs or ignore what I wrote above and just
> > fail.
> >
> > Hannes's patches fix up the eh callouts so they don't pass in a scsi_cmnd
> > when it's not needed. That seems nice because after that, then for your new
> > EH we can begin to standardize on how to handle preallocation of drivers
> > resources needed to perform TMFs for your new EH. It could be a per
> > device/target/host callout to allow drivers to preallocate, then scsi-ml calls
> > into the drivers with that data. It doesn't have to be exactly like that or
> > anything close. It would be nice for drivers to not have to think about this
> > type of thing and scsi-ml just to handle the resource management for us when
> > there are multiple TMFs in progress.
>
> Exactly!

Yeah, thanks for the vote of support.
Last time I tried the attempt got shot down, as it had been using the 
'wrong' interface. But seeing that there's renewed interest I'll be 
reposting them.

Cheers,

Hannes
--
Dr. Hannes Reinecke                Kernel Storage Architect
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