Re: libata EH appears to be NFG up to 2.6.17 (at least).

[Jeff Garzik <jgarzik@pobox.com>]

Mark Lord wrote:
> Got your attention now?  Good!
> 
> I am doing some testing with known-bad drives on 2.6.16 (and 2.6.17).
> 
> Libata EH is wretched there, because it does not seem to be careful
> about reading/saving the bad ata_status value when an error occurs.
> 
> The ata_status from a failed/aborted command is first read in
> the interrupt handler, either by the LLD or by ata_host_intr().
> 
> This value is not saved for reuse anywhere, and the next time it is read,
> the reader will see ATA_ERR==0, and then not do the Right Thing (tm).
> 
> Who reads it next, you ask?  Well, it gets read *again* from libata-scsi
> when it is trying to generate meaningful sense data.  But at that point,
> all that is seen is 0x50 -- "success".
> 
> So libata-scsi returns incorrect (or no) sense data to the SCSI mid-layer,
> and the error is mishandled or ignored.
> 
> Ugh.  The distro folks will probably want to fix this in their 2.6.1[56]
> based distro kernels.  I don't yet see a way to do this without modifying
> core data structures (eg. adding an ata_status field to the qc).

What driver?
What architecture?
What kernel config?
How does 2.6.18-rc1, with vastly different EH, behave?

	Jeff