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    SubjectRe: [RFC PATCH v2 00/18] scsi: scsi_error: Introduce new error handle mechanism
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    On 2023/9/27 15:59, Hannes Reinecke wrote:
    > On 9/26/23 14:57, Wenchao Hao wrote:
    >> On 2023/9/26 1:54, Mike Christie wrote:
    >>> On 9/25/23 10:07 AM, Wenchao Hao wrote:
    >>>> On 2023/9/25 22:55, Christoph Hellwig wrote:
    >>>>> Before we add another new error handling mechanism we need to fix the
    >>>>> old one first.  Hannes' work on not passing the scsi_cmnd to the various
    >>>>> reset handlers hasn't made a lot of progress in the last five years and
    >>>>> we'll need to urgently fix that first before adding even more
    >>>>> complexity.
    >>>>>
    >>>> I observed Hannes's patches posted about one year ago, it has not been
    >>>> applied yet. I don't know if he is still working on it.
    >>>>
    >>>> My patches do not depend much on that work, I think the conflict can be
    >>>> solved fast between two changes.
    >>>
    >>> I think we want to figure out Hannes's patches first.
    >>>
    >>> For a new EH design we will want to be able to do multiple TMFs in parallel
    >>> on the same host/target right?
    >>>
    >>
    >> It's not necessary to do multiple TMFs in parallel, it's ok to make sure
    >> each TMFs do not affect each other.
    >>
    >> For example, we have two devices: 0:0:0:0 and 0:0:0:1
    >>
    >> Both of them request device reset, they do not happened in parallel, but
    >> would in serial. If 0:0:0:0 is performing device reset in progress, 0:0:0:1
    >> just wait 0:0:0:0 to finish.
    >>
    > Well, not quite. Any higher-order TMFs are serialized by virtue of SCSI-EH, but command aborts (which also devolve down to TMFs on certain drivers) do run in parallel, and there we will be requiring multiple TMFs.
    >

    It's best that multiple TMFs can run in parallel, again, looking forwarding
    to your changes.

    > Cheers,
    >
    > Hannes

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