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Date: Fri, 1 Mar 2024 14:58:15 -0800
From: Igor Pylypiv <ipylypiv@google.com>
To: Damien Le Moal <dlemoal@kernel.org>
Cc: Niklas Cassel <cassel@kernel.org>, John Garry <john.g.garry@oracle.com>,
	Jason Yan <yanaijie@huawei.com>,
	"James E.J. Bottomley" <jejb@linux.ibm.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	Jack Wang <jinpu.wang@cloud.ionos.com>,
	Hannes Reinecke <hare@suse.de>, linux-ide@vger.kernel.org,
	linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org,
	TJ Adams <tadamsjr@google.com>
Subject: Re: [PATCH 1/3] ata: libata-sata: Factor out NCQ Priority
 configuration helpers
Message-ID: <ZeJdhyYsUVUwpCL8@google.com>
References: <20240301013759.516817-1-ipylypiv@google.com>
 <20240301013759.516817-2-ipylypiv@google.com>
 <cee98fdf-d285-44da-8bcb-9d9150a19e5e@kernel.org>
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In-Reply-To: <cee98fdf-d285-44da-8bcb-9d9150a19e5e@kernel.org>

On Fri, Mar 01, 2024 at 04:16:46AM -0800, Damien Le Moal wrote:

Thank you for the review Damien!

> On 2024/02/29 17:37, Igor Pylypiv wrote:
> > Export libata NCQ Priority configuration helpers to be reused
> > for libsas managed SATA devices.
> > 
> > Signed-off-by: Igor Pylypiv <ipylypiv@google.com>
> > Reviewed-by: TJ Adams <tadamsjr@google.com>
> 
> Please drop this tag as the email signaling the review was not sent to the
> list/in-reply to this email. The name of the reviewer should also be fully
> spelled out. Same comment for the other 2 patches as they also have this review tag.
> 
> > ---
> >  drivers/ata/libata-sata.c | 130 +++++++++++++++++++++++++-------------
> >  include/linux/libata.h    |   4 ++
> >  2 files changed, 90 insertions(+), 44 deletions(-)
> > 
> > diff --git a/drivers/ata/libata-sata.c b/drivers/ata/libata-sata.c
> > index 0fb1934875f2..9c6c69d7feab 100644
> > --- a/drivers/ata/libata-sata.c
> > +++ b/drivers/ata/libata-sata.c
> > @@ -848,80 +848,104 @@ 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);
> > +	rc = dev ? !!(dev->flags & ATA_DFLAG_NCQ_PRIO) : -ENODEV;
> 
> Please expand this to make it more readable:
> 
> 	if (!dev)
> 		rc = -ENODEV;
> 	else
> 		rc = !!(dev->flags & ATA_DFLAG_NCQ_PRIO);
> 
> > +	spin_unlock_irqrestore(ap->lock, flags);
> > +	return rc;
> > +}
> > +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);
> > -	struct ata_device *dev;
> > -	bool ncq_prio_supported;
> > -	int rc = 0;
> > -
> > -	spin_lock_irq(ap->lock);
> > -	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);
> > +	int rc = ata_ncq_prio_supported(ap, sdev);
> >  
> > -	return rc ? rc : sysfs_emit(buf, "%u\n", ncq_prio_supported);
> > +	return (rc < 0) ? rc : sysfs_emit(buf, "%u\n", rc);
> 
> Same here, please expand:
> 
> 	if (rc < 0)
> 		return rc;
> 	return sysfs_emit(buf, "%d\n", rc);
> 
> And please not the change %u -> %d
> 
> >  }
> > -
> 
> whiteline change. Please keep the white line.
> 
> >  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.
> > + */
> > +int ata_ncq_prio_enabled(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);
> > +	rc = dev ? !!(dev->flags & ATA_DFLAG_NCQ_PRIO_ENABLED) : -ENODEV;
> 
> same comment as above. Please expand.
> 
> > +	spin_unlock_irqrestore(ap->lock, flags);
> > +	return rc;
> > +}
> > +EXPORT_SYMBOL_GPL(ata_ncq_prio_enabled);
> > +
> >  static ssize_t ata_ncq_prio_enable_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);
> > -	struct ata_device *dev;
> > -	bool ncq_prio_enable;
> > -	int rc = 0;
> > -
> > -	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);
> > +	int rc = ata_ncq_prio_enabled(ap, sdev);
> >  
> > -	return rc ? rc : sysfs_emit(buf, "%u\n", ncq_prio_enable);
> > +	return (rc < 0) ? rc : sysfs_emit(buf, "%u\n", rc);
> 
> same comment as above.
> 
> >  }
> >  
> > -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);
> 
> Any reason to not use spin_lock_irq() ?

In the future someone might call these helper functions when interrupts
are disabled. spin_unlock_irq() might re-enable interrupts prematurely.
spin_unlock_irqrestore() will restore the same interrupts state that was
before the call to spin_lock_irqsave().

> 
> >  
> > -	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)) {
> > +		rc = -ENODEV;
> > +		goto unlock;
> > +	}
> >  
> >  	if (!(dev->flags & ATA_DFLAG_NCQ_PRIO)) {
> >  		rc = -EINVAL;
> >  		goto unlock;
> >  	}
> >  
> > -	if (input) {
> > +	if (enable) {
> >  		if (dev->flags & ATA_DFLAG_CDL_ENABLED) {
> >  			ata_dev_err(dev,
> >  				"CDL must be disabled to enable NCQ priority\n");
> > @@ -934,9 +958,27 @@ static ssize_t ata_ncq_prio_enable_store(struct device *device,
> >  	}
> >  
> >  unlock:
> > -	spin_unlock_irq(ap->lock);
> > +	spin_unlock_irqrestore(ap->lock, flags);
> > +	return rc;
> > +}
> > +EXPORT_SYMBOL_GPL(ata_ncq_prio_enable);
> > +
> > +static ssize_t ata_ncq_prio_enable_store(struct device *device,
> > +					 struct device_attribute *attr,
> > +					 const char *buf, size_t len)
> > +{
> > +	struct scsi_device *sdev = to_scsi_device(device);
> > +	struct ata_port *ap = ata_shost_to_port(sdev->host);
> > +	long input;
> > +	int rc = 0;
> > +
> > +	rc = kstrtol(buf, 10, &input);
> 
> Please use kstrtobool().
> 
> > +	if (rc)
> > +		return rc;
> > +	if ((input < 0) || (input > 1))
> > +		return -EINVAL;
> >  
> > -	return rc ? rc : len;
> > +	return ata_ncq_prio_enable(ap, sdev, input) ? : len;
> >  }
> >  
> >  DEVICE_ATTR(ncq_prio_enable, S_IRUGO | S_IWUSR,
> > diff --git a/include/linux/libata.h b/include/linux/libata.h
> > index 26d68115afb8..f3ff2bf3ec6b 100644
> > --- a/include/linux/libata.h
> > +++ b/include/linux/libata.h
> > @@ -1157,6 +1157,10 @@ extern int ata_scsi_change_queue_depth(struct scsi_device *sdev,
> >  				       int queue_depth);
> >  extern int ata_change_queue_depth(struct ata_port *ap, struct scsi_device *sdev,
> >  				  int queue_depth);
> > +extern int ata_ncq_prio_supported(struct ata_port *ap, struct scsi_device *sdev);
> > +extern int ata_ncq_prio_enabled(struct ata_port *ap, struct scsi_device *sdev);
> > +extern int ata_ncq_prio_enable(struct ata_port *ap, struct scsi_device *sdev,
> > +			       bool enable);
> >  extern struct ata_device *ata_dev_pair(struct ata_device *adev);
> >  extern int ata_do_set_mode(struct ata_link *link, struct ata_device **r_failed_dev);
> >  extern void ata_scsi_port_error_handler(struct Scsi_Host *host, struct ata_port *ap);
> 
> -- 
> Damien Le Moal
> Western Digital Research
>