Re: [RFC PATCH v3 1/4] block: add a flag to identify PM request

[Lin Ming]

On Wed, May 23, 2012 at 11:02 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
> On Tue, 22 May 2012, Lin Ming wrote:
>
>> Add a flag REQ_PM to identify the request is PM related.
>> As an example, modify scsi code to use this flag.
>
> Don't forget to check up on the SCSI error handler.  If I'm not
> mistaken, the libata drivers use it during suspend and resume.  Also,

You are right.

ata_port_suspend_common
  ata_port_request_pm
    ata_port_schedule_eh
      scsi_schedule_eh
        scsi_error_handler ---> libata error handler

I just have a quick look and it seems libata error handler does not
send SCSI request.
Will check more.

> the error handler will run if one of the REQ_PM commands encounters an
> error.
>
> Therefore it seems likely that every request submitted by the error
> handler needs to have REQ_PM set.
>
> Alan Stern
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