linux-kernel - Re: [PATCH v3 5/6] ata: libata: Set ATA_QCFLAG_RTF_FILLED in fill_result

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Message-ID: <Zn9CXRMWFczmG_P3@google.com>
Date: Fri, 28 Jun 2024 23:08:13 +0000
From: Igor Pylypiv <ipylypiv@...gle.com>
To: Niklas Cassel <cassel@...nel.org>
Cc: Damien Le Moal <dlemoal@...nel.org>, Tejun Heo <tj@...nel.org>,
	Hannes Reinecke <hare@...e.de>, linux-ide@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 5/6] ata: libata: Set ATA_QCFLAG_RTF_FILLED in
 fill_result_tf()

On Fri, Jun 28, 2024 at 10:12:19PM +0200, Niklas Cassel wrote:
> On Wed, Jun 26, 2024 at 11:04:10PM +0000, Igor Pylypiv wrote:
> > ATA_QCFLAG_RTF_FILLED is not specific to ahci and can be used generally
> > to check if qc->result_tf contains valid data.
> > 
> > Reviewed-by: Hannes Reinecke <hare@...e.de>
> > Reviewed-by: Damien Le Moal <dlemoal@...nel.org>
> > Signed-off-by: Igor Pylypiv <ipylypiv@...gle.com>
> > ---
> >  drivers/ata/libahci.c     | 10 ----------
> >  drivers/ata/libata-core.c |  8 ++++++++
> >  2 files changed, 8 insertions(+), 10 deletions(-)
> > 
> > diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
> > index 83431aae74d8..0728d445e531 100644
> > --- a/drivers/ata/libahci.c
> > +++ b/drivers/ata/libahci.c
> > @@ -2075,13 +2075,6 @@ static void ahci_qc_fill_rtf(struct ata_queued_cmd *qc)
> >  	struct ahci_port_priv *pp = qc->ap->private_data;
> >  	u8 *rx_fis = pp->rx_fis;
> >  
> > -	/*
> > -	 * rtf may already be filled (e.g. for successful NCQ commands).
> > -	 * If that is the case, we have nothing to do.
> > -	 */
> > -	if (qc->flags & ATA_QCFLAG_RTF_FILLED)
> > -		return;
> > -
> >  	if (pp->fbs_enabled)
> >  		rx_fis += qc->dev->link->pmp * AHCI_RX_FIS_SZ;
> >  
> > @@ -2095,7 +2088,6 @@ static void ahci_qc_fill_rtf(struct ata_queued_cmd *qc)
> >  	    !(qc->flags & ATA_QCFLAG_EH)) {
> >  		ata_tf_from_fis(rx_fis + RX_FIS_PIO_SETUP, &qc->result_tf);
> >  		qc->result_tf.status = (rx_fis + RX_FIS_PIO_SETUP)[15];
> > -		qc->flags |= ATA_QCFLAG_RTF_FILLED;
> >  		return;
> >  	}
> >  
> > @@ -2118,12 +2110,10 @@ static void ahci_qc_fill_rtf(struct ata_queued_cmd *qc)
> >  		 */
> >  		qc->result_tf.status = fis[2];
> >  		qc->result_tf.error = fis[3];
> > -		qc->flags |= ATA_QCFLAG_RTF_FILLED;
> >  		return;
> >  	}
> >  
> >  	ata_tf_from_fis(rx_fis + RX_FIS_D2H_REG, &qc->result_tf);
> > -	qc->flags |= ATA_QCFLAG_RTF_FILLED;
> >  }
> >  
> >  static void ahci_qc_ncq_fill_rtf(struct ata_port *ap, u64 done_mask)
> > diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
> > index e1bf8a19b3c8..a9fc3ec9300f 100644
> > --- a/drivers/ata/libata-core.c
> > +++ b/drivers/ata/libata-core.c
> > @@ -4801,8 +4801,16 @@ static void fill_result_tf(struct ata_queued_cmd *qc)
> >  {
> >  	struct ata_port *ap = qc->ap;
> >  
> > +	/*
> > +	 * rtf may already be filled (e.g. for successful NCQ commands).
> > +	 * If that is the case, we have nothing to do.
> > +	 */
> > +	if (qc->flags & ATA_QCFLAG_RTF_FILLED)
> > +		return;
> > +
> >  	qc->result_tf.flags = qc->tf.flags;
> 
> One functional change that I can see from this is that after this commit,
> we will no longer do: qc->result_tf.flags = qc->tf.flags;
> if ATA_QCFLAG_RTF_FILLED was set.

Nice catch, Niklas! I'll fix it in v4. Thank you!

> 
> e.g. ata_scsi_set_passthru_sense_fields() and ata_gen_ata_sense()
> makes use of result_tf->flags, so we probably still want to do this.
> 
> 
> Perhaps keep this function as you have it and simply do:
> 
> diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
> index 0728d445e531..fdfa7b266218 100644
> --- a/drivers/ata/libahci.c
> +++ b/drivers/ata/libahci.c
> @@ -2148,6 +2148,7 @@ static void ahci_qc_ncq_fill_rtf(struct ata_port *ap, u64 done_mask)
>                         if (qc && ata_is_ncq(qc->tf.protocol)) {
>                                 qc->result_tf.status = status;
>                                 qc->result_tf.error = error;
> +                               qc->result_tf.flags = qc->tf.flags;
>                                 qc->flags |= ATA_QCFLAG_RTF_FILLED;
>                         }
>                         done_mask &= ~(1ULL << tag);
> @@ -2172,6 +2173,7 @@ static void ahci_qc_ncq_fill_rtf(struct ata_port *ap, u64 done_mask)
>                         fis += RX_FIS_SDB;
>                         qc->result_tf.status = fis[2];
>                         qc->result_tf.error = fis[3];
> +                       qc->result_tf.flags = qc->tf.flags;
>                         qc->flags |= ATA_QCFLAG_RTF_FILLED;
>                 }
>                 done_mask &= ~(1ULL << tag);
> 
> 
> 
> >  	ap->ops->qc_fill_rtf(qc);
> > +	qc->flags |= ATA_QCFLAG_RTF_FILLED;
> >  }
> >  
> >  static void ata_verify_xfer(struct ata_queued_cmd *qc)
> > -- 
> > 2.45.2.803.g4e1b14247a-goog
> >