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Date:   Sat, 18 Jul 2020 08:13:26 -0700
From:   Guenter Roeck <linux@roeck-us.net>
To:     "Maciej S. Szmigiero" <mail@maciej.szmigiero.name>
Cc:     Jean Delvare <jdelvare@suse.com>, linux-hwmon@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] hwmon: (drivetemp) Avoid SCT usage on Toshiba DT01ACA
 family drives
Message-ID: <20200718151326.GA163203@roeck-us.net>
References: <0cb2e7022b66c6d21d3f189a12a97878d0e7511b.1595075458.git.mail@maciej.szmigiero.name>
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On Sat, Jul 18, 2020 at 02:32:10PM +0200, Maciej S. Szmigiero wrote:
> It has been observed that Toshiba DT01ACA family drives have
> WRITE FPDMA QUEUED command timeouts and sometimes just freeze until
> power-cycled under heavy write loads when their temperature is getting
> polled in SCT mode. The SMART mode seems to be fine, though.
> 
> Let's make sure we don't use SCT mode for these drives then.
> 
> While only the 3 TB model was actually caught exhibiting the problem let's
> play safe here to avoid data corruption and extend the ban to the whole
> family.
> 
> Fixes: 5b46903d8bf3 ("hwmon: Driver for disk and solid state drives with temperature sensors")
> Cc: stable@vger.kernel.org
> Signed-off-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>

Applied.

Thanks,
Guenter

> ---
> 
> Notes:
>     This behavior was observed on two different DT01ACA3 drives.
>     
>     Usually, a series of queued WRITE FPDMA QUEUED commands just time out,
>     but sometimes the whole drive freezes. Merely disconnecting and
>     reconnecting SATA interface cable then does not unfreeze the drive.
>     
>     One has to disconnect and reconnect the drive power connector for the
>     drive to be detected again (suggesting the drive firmware itself has
>     crashed).
>     
>     This only happens when the drive temperature is polled very often (like
>     every second), so occasional SCT usage via smartmontools is probably
>     safe.
>     
>     Changes from v1:
>     'SCT blacklist' -> 'SCT avoid models'
>     
>     Changes from v2:
>     * Switch to prefix matching and use it to match the DT01ACAx family,
>     
>     * Use "!" instead of "== 0",
>     
>     * Add a comment about the contents of the "model" field.
> 
>  drivers/hwmon/drivetemp.c | 43 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 43 insertions(+)
> 
> diff --git a/drivers/hwmon/drivetemp.c b/drivers/hwmon/drivetemp.c
> index 0d4f3d97ffc6..72c760373957 100644
> --- a/drivers/hwmon/drivetemp.c
> +++ b/drivers/hwmon/drivetemp.c
> @@ -285,6 +285,42 @@ static int drivetemp_get_scttemp(struct drivetemp_data *st, u32 attr, long *val)
>  	return err;
>  }
>  
> +static const char * const sct_avoid_models[] = {
> +/*
> + * These drives will have WRITE FPDMA QUEUED command timeouts and sometimes just
> + * freeze until power-cycled under heavy write loads when their temperature is
> + * getting polled in SCT mode. The SMART mode seems to be fine, though.
> + *
> + * While only the 3 TB model (DT01ACA3) was actually caught exhibiting the
> + * problem let's play safe here to avoid data corruption and ban the whole
> + * DT01ACAx family.
> +
> + * The models from this array are prefix-matched.
> + */
> +	"TOSHIBA DT01ACA",
> +};
> +
> +static bool drivetemp_sct_avoid(struct drivetemp_data *st)
> +{
> +	struct scsi_device *sdev = st->sdev;
> +	unsigned int ctr;
> +
> +	if (!sdev->model)
> +		return false;
> +
> +	/*
> +	 * The "model" field contains just the raw SCSI INQUIRY response
> +	 * "product identification" field, which has a width of 16 bytes.
> +	 * This field is space-filled, but is NOT NULL-terminated.
> +	 */
> +	for (ctr = 0; ctr < ARRAY_SIZE(sct_avoid_models); ctr++)
> +		if (!strncmp(sdev->model, sct_avoid_models[ctr],
> +			     strlen(sct_avoid_models[ctr])))
> +			return true;
> +
> +	return false;
> +}
> +
>  static int drivetemp_identify_sata(struct drivetemp_data *st)
>  {
>  	struct scsi_device *sdev = st->sdev;
> @@ -326,6 +362,13 @@ static int drivetemp_identify_sata(struct drivetemp_data *st)
>  	/* bail out if this is not a SATA device */
>  	if (!is_ata || !is_sata)
>  		return -ENODEV;
> +
> +	if (have_sct && drivetemp_sct_avoid(st)) {
> +		dev_notice(&sdev->sdev_gendev,
> +			   "will avoid using SCT for temperature monitoring\n");
> +		have_sct = false;
> +	}
> +
>  	if (!have_sct)
>  		goto skip_sct;
>