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Date: Mon, 4 Mar 2024 08:34:52 +0000
From: John Garry <john.g.garry@...cle.com>
To: Igor Pylypiv <ipylypiv@...gle.com>, Damien Le Moal <dlemoal@...nel.org>,
Niklas Cassel <cassel@...nel.org>, Jason Yan <yanaijie@...wei.com>,
"James E.J. Bottomley" <jejb@...ux.ibm.com>,
"Martin K. Petersen" <martin.petersen@...cle.com>,
Jack Wang <jinpu.wang@...ud.ionos.com>, Hannes Reinecke <hare@...e.de>,
Xiang Chen <chenxiang66@...ilicon.com>,
Artur Paszkiewicz <artur.paszkiewicz@...el.com>,
Bart Van Assche <bvanassche@....org>
Cc: TJ Adams <tadamsjr@...gle.com>, linux-ide@...r.kernel.org,
linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/7] ata: libata-sata: Factor out NCQ Priority
configuration helpers
On 02/03/2024 20:16, Igor Pylypiv wrote:
> Export libata NCQ Priority configuration helpers to be reused
> for libsas managed SATA devices.
>
> Signed-off-by: Igor Pylypiv <ipylypiv@...gle.com>
This looks ok. Some small code comments below, though.
> ---
> drivers/ata/libata-sata.c | 139 +++++++++++++++++++++++++++-----------
> include/linux/libata.h | 4 ++
> 2 files changed, 103 insertions(+), 40 deletions(-)
>
> diff --git a/drivers/ata/libata-sata.c b/drivers/ata/libata-sata.c
> index 0fb1934875f2..a8d5e36d5211 100644
> --- a/drivers/ata/libata-sata.c
> +++ b/drivers/ata/libata-sata.c
> @@ -848,29 +848,73 @@ DEVICE_ATTR(link_power_management_policy, S_IRUGO | S_IWUSR,
> ata_scsi_lpm_show, ata_scsi_lpm_store);
> EXPORT_SYMBOL_GPL(dev_attr_link_power_management_policy);
>
> +/**
> + * ata_ncq_prio_supported - Check if device supports NCQ Priority
> + * @ap: ATA port of the target device
> + * @sdev: SCSI device
> + *
> + * Helper to check if device supports NCQ Priority feature,
> + * usable with both libsas and libata.
> + */
> +int ata_ncq_prio_supported(struct ata_port *ap, struct scsi_device *sdev)
> +{
> + struct ata_device *dev;
> + unsigned long flags;
> + int rc;
> +
> + spin_lock_irqsave(ap->lock, flags);
> + dev = ata_scsi_find_dev(ap, sdev);
> + if (!dev)
> + rc = -ENODEV;
> + else
> + rc = !!(dev->flags & ATA_DFLAG_NCQ_PRIO);
> + spin_unlock_irqrestore(ap->lock, flags);
> + return rc;
> +}
I'm not the biggest fan of functions which effectively return both a
boolean and an error code.
I like this patten more:
int ata_ncq_prio_supported(struct ata_port *ap, struct scsi_device
*sdev, bool *supported)
{
...
if (rc)
return rc;
*supported = true/false.
return 0;
}
No big deal, though.
> +EXPORT_SYMBOL_GPL(ata_ncq_prio_supported);
> +
> static ssize_t ata_ncq_prio_supported_show(struct device *device,
> struct device_attribute *attr,
> char *buf)
> {
> struct scsi_device *sdev = to_scsi_device(device);
> struct ata_port *ap = ata_shost_to_port(sdev->host);
> + int rc;
> +
> + rc = ata_ncq_prio_supported(ap, sdev);
> + if (rc < 0)
> + return rc;
> +
> + return sysfs_emit(buf, "%d\n", rc);
> +}
> +
> +DEVICE_ATTR(ncq_prio_supported, S_IRUGO, ata_ncq_prio_supported_show, NULL);
> +EXPORT_SYMBOL_GPL(dev_attr_ncq_prio_supported);
> +
> +/**
> + * ata_ncq_prio_enabled - Check if NCQ Priority is enabled
> + * @ap: ATA port of the target device
> + * @sdev: SCSI device
> + *
> + * Helper to check if NCQ Priority feature is enabled,
> + * usable with both libsas and libata.
It's usable by anything which uses libata, really. For the moment that
is libsas and libata.
> + */
> +int ata_ncq_prio_enabled(struct ata_port *ap, struct scsi_device *sdev)
> +{
> struct ata_device *dev;
> - bool ncq_prio_supported;
> - int rc = 0;
> + unsigned long flags;
> + int rc;
>
> - spin_lock_irq(ap->lock);
> + spin_lock_irqsave(ap->lock, flags);
> dev = ata_scsi_find_dev(ap, sdev);
> if (!dev)
> rc = -ENODEV;
> else
> - ncq_prio_supported = dev->flags & ATA_DFLAG_NCQ_PRIO;
> - spin_unlock_irq(ap->lock);
> -
> - return rc ? rc : sysfs_emit(buf, "%u\n", ncq_prio_supported);
> + rc = !!(dev->flags & ATA_DFLAG_NCQ_PRIO_ENABLED);
> + spin_unlock_irqrestore(ap->lock, flags);
> + return rc;
> }
> -
> -DEVICE_ATTR(ncq_prio_supported, S_IRUGO, ata_ncq_prio_supported_show, NULL);
> -EXPORT_SYMBOL_GPL(dev_attr_ncq_prio_supported);
> +EXPORT_SYMBOL_GPL(ata_ncq_prio_enabled);
>
> static ssize_t ata_ncq_prio_enable_show(struct device *device,
> struct device_attribute *attr,
> @@ -878,50 +922,45 @@ static ssize_t ata_ncq_prio_enable_show(struct device *device,
> {
> struct scsi_device *sdev = to_scsi_device(device);
> struct ata_port *ap = ata_shost_to_port(sdev->host);
> - struct ata_device *dev;
> - bool ncq_prio_enable;
> - int rc = 0;
> + int rc;
>
> - spin_lock_irq(ap->lock);
> - dev = ata_scsi_find_dev(ap, sdev);
> - if (!dev)
> - rc = -ENODEV;
> - else
> - ncq_prio_enable = dev->flags & ATA_DFLAG_NCQ_PRIO_ENABLED;
> - spin_unlock_irq(ap->lock);
> + rc = ata_ncq_prio_enabled(ap, sdev);
> + if (rc < 0)
> + return rc;
>
> - return rc ? rc : sysfs_emit(buf, "%u\n", ncq_prio_enable);
> + return sysfs_emit(buf, "%d\n", rc);
> }
>
> -static ssize_t ata_ncq_prio_enable_store(struct device *device,
> - struct device_attribute *attr,
> - const char *buf, size_t len)
> +/**
> + * ata_ncq_prio_enable - Enable/disable NCQ Priority
> + * @ap: ATA port of the target device
> + * @sdev: SCSI device
> + * @enable: true - enable NCQ Priority, false - disable NCQ Priority
> + *
> + * Helper to enable/disable NCQ Priority feature, usable with both
> + * libsas and libata.
> + */
> +int ata_ncq_prio_enable(struct ata_port *ap, struct scsi_device *sdev,
> + bool enable)
> {
> - struct scsi_device *sdev = to_scsi_device(device);
> - struct ata_port *ap;
> struct ata_device *dev;
> - long int input;
> + unsigned long flags;
> int rc = 0;
>
> - rc = kstrtol(buf, 10, &input);
> - if (rc)
> - return rc;
> - if ((input < 0) || (input > 1))
> - return -EINVAL;
> + spin_lock_irqsave(ap->lock, flags);
>
> - ap = ata_shost_to_port(sdev->host);
> dev = ata_scsi_find_dev(ap, sdev);
> - if (unlikely(!dev))
> - return -ENODEV;
> -
> - spin_lock_irq(ap->lock);
> + if (unlikely(!dev)) {
no need for unlikely() - this is not fathpath
> + rc = -ENODEV;
> + goto unlock;
> + }
>
> if (!(dev->flags & ATA_DFLAG_NCQ_PRIO)) {
> rc = -EINVAL;
> goto unlock;
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