linux-kernel - Re: [PATCH v2 6/6] ata: libata-scsi: Check ATA_QCFLAG_RTF_FILLED before using result

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Date: Tue, 25 Jun 2024 08:26:59 +0200
From: Hannes Reinecke <hare@...e.de>
To: Igor Pylypiv <ipylypiv@...gle.com>, Damien Le Moal <dlemoal@...nel.org>,
 Niklas Cassel <cassel@...nel.org>
Cc: Tejun Heo <tj@...nel.org>, "Martin K. Petersen"
 <martin.petersen@...cle.com>, Jason Yan <yanaijie@...wei.com>,
 linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 6/6] ata: libata-scsi: Check ATA_QCFLAG_RTF_FILLED
 before using result_tf

On 6/25/24 00:12, Igor Pylypiv wrote:
> qc->result_tf contents are only valid when the ATA_QCFLAG_RTF_FILLED flag
> is set. The ATA_QCFLAG_RTF_FILLED flag should be always set for commands
> that failed or for commands that have the ATA_QCFLAG_RESULT_TF flag set.
> 
> For ATA errors and ATA PASS-THROUGH commands the ATA_QCFLAG_RTF_FILLED
> flag should be always set. Added WARN_ON_ONCE() checks to generate
> a warning when ATA_QCFLAG_RTF_FILLED is not set and libata needs to
> generate sense data.
> 
> Signed-off-by: Igor Pylypiv <ipylypiv@...gle.com>
> ---
>   drivers/ata/libata-scsi.c | 10 ++++++++++
>   1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
> index e5669a296d81..7a8a08692ce9 100644
> --- a/drivers/ata/libata-scsi.c
> +++ b/drivers/ata/libata-scsi.c
> @@ -246,6 +246,9 @@ static void ata_scsi_set_passthru_sense_fields(struct ata_queued_cmd *qc)
>   	struct ata_taskfile *tf = &qc->result_tf;
>   	unsigned char *sb = cmd->sense_buffer;
>   
> +	if (WARN_ON_ONCE(!(qc->flags & ATA_QCFLAG_RTF_FILLED)))
> +		return;
> +
>   	if ((sb[0] & 0x7f) >= 0x72) {
>   		unsigned char *desc;
>   		u8 len;
> @@ -928,6 +931,9 @@ static void ata_gen_passthru_sense(struct ata_queued_cmd *qc)
>   	unsigned char *sb = cmd->sense_buffer;
>   	u8 sense_key, asc, ascq;
>   
> +	if (WARN_ON_ONCE(!(qc->flags & ATA_QCFLAG_RTF_FILLED)))
> +		return;
> +
>   	/*
>   	 * Use ata_to_sense_error() to map status register bits
>   	 * onto sense key, asc & ascq.
> @@ -971,6 +977,10 @@ static void ata_gen_ata_sense(struct ata_queued_cmd *qc)
>   		ata_scsi_set_sense(dev, cmd, NOT_READY, 0x04, 0x21);
>   		return;
>   	}
> +
> +	if (WARN_ON_ONCE(!(qc->flags & ATA_QCFLAG_RTF_FILLED)))
> +		return;
> +
>   	/* Use ata_to_sense_error() to map status register bits
>   	 * onto sense key, asc & ascq.
>   	 */

Hmm. Not sure if we really need the WARN_ON() here or whether a simple 
logging message wouldn't be sufficient; after all, we continue fine here.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@...e.de                                +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich