linux-kernel - Re: [PATCH] libata: Fix retrieving of active qcs

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Date:   Fri, 13 Dec 2019 09:05:08 +0100
From:   Sascha Hauer <s.hauer@...gutronix.de>
To:     linux-ide@...r.kernel.org
Cc:     Jens Axboe <axboe@...nel.dk>, linux-kernel@...r.kernel.org,
        kernel@...gutronix.de
Subject: Re: [PATCH] libata: Fix retrieving of active qcs

On Fri, Dec 13, 2019 at 09:03:34AM +0100, Sascha Hauer wrote:
> ata_qc_complete_multiple() is called with a mask of the still active
> tags.
> 
> mv_sata doesn't have this information directly and instead calculates
> the still active tags from the started tags (ap->qc_active) and the
> finished tags as (ap->qc_active ^ done_mask)
> 
> Since 28361c40368 the hw_tag and tag are no longer the same and the
> equation is no longer valid. In ata_exec_internal_sg() ap->qc_active is
> initialized as 1ULL << ATA_TAG_INTERNAL, but in hardware tag 0 is
> started and this will be in done_mask on completion. ap->qc_active ^
> done_mask becomes 0x100000000 ^ 0x1 = 0x100000001 and thus tag 0 used as
> the internal tag will never be reported as completed.
> 
> This is fixed by introducing ata_qc_get_active() which returns the
> active hardware tags and calling it where appropriate.
> 
> This is tested on mv_sata, but sata_fsl and sata_nv suffer from the same
> problem. There is another case in sata_nv that most likely needs fixing
> as well, but this looks a little different, so I wasn't confident enough
> to change that.
> 
> Fixes: 28361c403683 ("libata: add extra internal command")
> Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
> ---

Ignore this, it lacks the v2 tag :-/

Sascha


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