[PATCH v8 1/7] ata: libata-sata: Factor out NCQ Priority configuration helpers

[Igor Pylypiv]

Export libata NCQ Priority configuration helpers to be reused
for libsas managed SATA devices.

Switched locking from spin_lock_irq() to spin_lock_irqsave().
In the future someone might call these helper functions when interrupts
are disabled. spin_unlock_irq() could lead to a premature re-enabling
of interrupts, whereas spin_unlock_irqrestore() restores the interrupt
state to its condition prior to the spin_lock_irqsave() call.

Acked-by: Damien Le Moal <dlemoal@xxxxxxxxxx>
Reviewed-by: Jason Yan <yanaijie@xxxxxxxxxx>
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
Signed-off-by: Igor Pylypiv <ipylypiv@xxxxxxxxxx>
---
 drivers/ata/libata-sata.c | 160 +++++++++++++++++++++++++++++---------
 include/linux/libata.h    |   6 ++
 2 files changed, 128 insertions(+), 38 deletions(-)

diff --git a/drivers/ata/libata-sata.c b/drivers/ata/libata-sata.c
index 0fb1934875f2..a8d773003d74 100644
--- a/drivers/ata/libata-sata.c
+++ b/drivers/ata/libata-sata.c
@@ -848,80 +848,143 @@ 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);
 
-static ssize_t ata_ncq_prio_supported_show(struct device *device,
-					   struct device_attribute *attr,
-					   char *buf)
+/**
+ *	ata_ncq_prio_supported - Check if device supports NCQ Priority
+ *	@ap: ATA port of the target device
+ *	@sdev: SCSI device
+ *	@supported: Address of a boolean to store the result
+ *
+ *	Helper to check if device supports NCQ Priority feature.
+ *
+ *	Context: Any context. Takes and releases @ap->lock.
+ *
+ *	Return:
+ *	* %0		- OK. Status is stored into @supported
+ *	* %-ENODEV	- Failed to find the ATA device
+ */
+int ata_ncq_prio_supported(struct ata_port *ap, struct scsi_device *sdev,
+			   bool *supported)
 {
-	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;
+	unsigned long flags;
 	int rc = 0;
 
-	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);
+		*supported = 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);
+	bool supported;
+	int rc;
+
+	rc = ata_ncq_prio_supported(ap, sdev, &supported);
+	if (rc)
+		return rc;
 
-	return rc ? rc : sysfs_emit(buf, "%u\n", ncq_prio_supported);
+	return sysfs_emit(buf, "%d\n", supported);
 }
 
 DEVICE_ATTR(ncq_prio_supported, S_IRUGO, ata_ncq_prio_supported_show, NULL);
 EXPORT_SYMBOL_GPL(dev_attr_ncq_prio_supported);
 
-static ssize_t ata_ncq_prio_enable_show(struct device *device,
-					struct device_attribute *attr,
-					char *buf)
+/**
+ *	ata_ncq_prio_enabled - Check if NCQ Priority is enabled
+ *	@ap: ATA port of the target device
+ *	@sdev: SCSI device
+ *	@enabled: Address of a boolean to store the result
+ *
+ *	Helper to check if NCQ Priority feature is enabled.
+ *
+ *	Context: Any context. Takes and releases @ap->lock.
+ *
+ *	Return:
+ *	* %0		- OK. Status is stored into @enabled
+ *	* %-ENODEV	- Failed to find the ATA device
+ */
+int ata_ncq_prio_enabled(struct ata_port *ap, struct scsi_device *sdev,
+			 bool *enabled)
 {
-	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;
+	unsigned long flags;
 	int rc = 0;
 
-	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_enable = dev->flags & ATA_DFLAG_NCQ_PRIO_ENABLED;
-	spin_unlock_irq(ap->lock);
+		*enabled = dev->flags & ATA_DFLAG_NCQ_PRIO_ENABLED;
+	spin_unlock_irqrestore(ap->lock, flags);
 
-	return rc ? rc : sysfs_emit(buf, "%u\n", ncq_prio_enable);
+	return rc;
 }
+EXPORT_SYMBOL_GPL(ata_ncq_prio_enabled);
 
-static ssize_t ata_ncq_prio_enable_store(struct device *device,
-					 struct device_attribute *attr,
-					 const char *buf, size_t len)
+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;
-	struct ata_device *dev;
-	long int input;
-	int rc = 0;
+	struct ata_port *ap = ata_shost_to_port(sdev->host);
+	bool enabled;
+	int rc;
 
-	rc = kstrtol(buf, 10, &input);
+	rc = ata_ncq_prio_enabled(ap, sdev, &enabled);
 	if (rc)
 		return rc;
-	if ((input < 0) || (input > 1))
-		return -EINVAL;
 
-	ap = ata_shost_to_port(sdev->host);
-	dev = ata_scsi_find_dev(ap, sdev);
-	if (unlikely(!dev))
-		return  -ENODEV;
+	return sysfs_emit(buf, "%d\n", enabled);
+}
+
+/**
+ *	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.
+ *
+ *	Context: Any context. Takes and releases @ap->lock.
+ *
+ *	Return:
+ *	* %0		- OK. Status is stored into @enabled
+ *	* %-ENODEV	- Failed to find the ATA device
+ *	* %-EINVAL	- NCQ Priority is not supported or CDL is enabled
+ */
+int ata_ncq_prio_enable(struct ata_port *ap, struct scsi_device *sdev,
+			bool enable)
+{
+	struct ata_device *dev;
+	unsigned long flags;
+	int rc = 0;
+
+	spin_lock_irqsave(ap->lock, flags);
 
-	spin_lock_irq(ap->lock);
+	dev = ata_scsi_find_dev(ap, sdev);
+	if (!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 +997,30 @@ 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);
+	bool enable;
+	int rc;
+
+	rc = kstrtobool(buf, &enable);
+	if (rc)
+		return rc;
+
+	rc = ata_ncq_prio_enable(ap, sdev, enable);
+	if (rc)
+		return rc;
 
-	return rc ? rc : len;
+	return len;
 }
 
 DEVICE_ATTR(ncq_prio_enable, S_IRUGO | S_IWUSR,
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 26d68115afb8..6dd9a4f9ca7c 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -1157,6 +1157,12 @@ 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,
+				  bool *supported);
+extern int ata_ncq_prio_enabled(struct ata_port *ap, struct scsi_device *sdev,
+				bool *enabled);
+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);
-- 
2.44.0.278.ge034bb2e1d-goog