On 10/29/2012 11:20 PM, Tejun Heo wrote:
> On Mon, Oct 29, 2012 at 05:01:32PM +0800, Aaron Lu wrote:
>> ata_exec_internal will preempt the ata link's active_tag and ata port's
>> qc_active flags, this is OK for error recovery, but if normal code path
>> wants to use ata_exec_internal, there is a problem: we need to check if
>> it is OK to issue a new command with the help of port_ops->defer.
>>
>> In ZPODD, I'll need to find out the loading mechanism of the ODD by
>> issuing a GET_CONFIGURATION command. And this command may very well
>> race with commands issued from SCSI layer. So instead of preempt the
>> current command, defer the new command if it's not OK to issue it, as
>> it is always wrong to issue a non-NCQ command when there is command(s)
>> in processing.
> 
> Why not do the discovery from EH?

Do you mean set a device level EH flag and then schedule EH to do the
discovery?

Thanks,
Aaron

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