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Message-ID: <ZeZH_jX4SO9YxgXk@google.com>
Date: Mon, 4 Mar 2024 14:15:26 -0800
From: Igor Pylypiv <ipylypiv@...gle.com>
To: John Garry <john.g.garry@...cle.com>
Cc: 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>,
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 Mon, Mar 04, 2024 at 08:34:52AM +0000, John Garry wrote:
> 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.
Thanks for the review, John. Separating out an error code and a boolean
makes the code a bit more readable. Sent out v4 with the changes.
>
> > +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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