ata: libata: Improve CDL resource management

The ncq_sense_buf buffer field of struct ata_port is allocated and used
only for devices that support the Command Duration Limits (CDL) feature.
However, the cdl buffer of struct ata_device, which is used to cache the
command duration limits log page for devices supporting CDL is always
allocated as part of struct ata_device, which is wasteful of memory for
devices that do not support this feature.

Clean this up by defining both buffers as part of the new ata_cdl
structure and allocating this structure only for devices that support
the CDL feature. This new structure is attached to struct ata_device
using the cdl pointer.

The functions ata_dev_init_cdl_resources() and
ata_dev_cleanup_cdl_resources() are defined to manage this new structure
allocation, initialization and freeing when a port is removed or a
device disabled. ata_dev_init_cdl_resources() is called from
ata_dev_config_cdl() only for devices that support CDL.
ata_dev_cleanup_cdl_resources() is called from ata_dev_free_resources()
to free the ata_cdl structure when a device is being disabled by EH.

Note that the name of the former cdl log buffer of struct ata_device is
changed to desc_log_buf to make it clearer that it is a buffer for the
limit descriptors log page.

This change reduces the size of struct ata_device, thus reducing memory
usage for ATA devices that do not support the CDL feature.

Signed-off-by: Damien Le Moal <[e-mail]>
Reviewed-by: Niklas Cassel <[e-mail]>

drivers/ata/libata-core.c

···
 		dev->flags |= ATA_DFLAG_TRUSTED;
 }
 
+void ata_dev_cleanup_cdl_resources(struct ata_device *dev)
+{
+	kfree(dev->cdl);
+	dev->cdl = NULL;
+}
+
+static int ata_dev_init_cdl_resources(struct ata_device *dev)
+{
+	struct ata_cdl *cdl = dev->cdl;
+	unsigned int err_mask;
+
+	if (!cdl) {
+		cdl = kzalloc(sizeof(*cdl), GFP_KERNEL);
+		if (!cdl)
+			return -ENOMEM;
+		dev->cdl = cdl;
+	}
+
+	err_mask = ata_read_log_page(dev, ATA_LOG_CDL, 0, cdl->desc_log_buf,
+				     ATA_LOG_CDL_SIZE / ATA_SECT_SIZE);
+	if (err_mask) {
+		ata_dev_warn(dev, "Read Command Duration Limits log failed\n");
+		ata_dev_cleanup_cdl_resources(dev);
+		return -EIO;
+	}
+
+	return 0;
+}
+
 static void ata_dev_config_cdl(struct ata_device *dev)
 {
-	struct ata_port *ap = dev->link->ap;
 	unsigned int err_mask;
 	bool cdl_enabled;
 	u64 val;
+	int ret;
 
 	if (ata_id_major_version(dev->id) < 11)
 		goto not_supported;
···
 		}
 	}
 
-	/*
-	 * Allocate a buffer to handle reading the sense data for successful
-	 * NCQ Commands log page for commands using a CDL with one of the limit
-	 * policy set to 0xD (successful completion with sense data available
-	 * bit set).
-	 */
-	if (!ap->ncq_sense_buf) {
-		ap->ncq_sense_buf = kmalloc(ATA_LOG_SENSE_NCQ_SIZE, GFP_KERNEL);
-		if (!ap->ncq_sense_buf)
-			goto not_supported;
-	}
-
-	/*
-	 * Command duration limits is supported: cache the CDL log page 18h
-	 * (command duration descriptors).
-	 */
-	err_mask = ata_read_log_page(dev, ATA_LOG_CDL, 0, dev->sector_buf, 1);
-	if (err_mask) {
-		ata_dev_warn(dev, "Read Command Duration Limits log failed\n");
+	/* CDL is supported: allocate and initialize needed resources. */
+	ret = ata_dev_init_cdl_resources(dev);
+	if (ret) {
+		ata_dev_warn(dev, "Initialize CDL resources failed\n");
 		goto not_supported;
 	}
 
-	memcpy(dev->cdl, dev->sector_buf, ATA_LOG_CDL_SIZE);
 	dev->flags |= ATA_DFLAG_CDL;
 
 	return;
 
 not_supported:
 	dev->flags &= ~(ATA_DFLAG_CDL | ATA_DFLAG_CDL_ENABLED);
-	kfree(ap->ncq_sense_buf);
-	ap->ncq_sense_buf = NULL;
+	ata_dev_cleanup_cdl_resources(dev);
 }
 
 static int ata_dev_config_lba(struct ata_device *dev)
···
 
 	kfree(ap->pmp_link);
 	kfree(ap->slave_link);
-	kfree(ap->ncq_sense_buf);
 	ida_free(&ata_ida, ap->print_id);
 	kfree(ap);
 }
···
 {
 	if (zpodd_dev_enabled(dev))
 		zpodd_exit(dev);
+
+	ata_dev_cleanup_cdl_resources(dev);
 }
 
 /**

drivers/ata/libata-sata.c

···
 {
 	struct ata_device *dev = link->device;
 	struct ata_port *ap = dev->link->ap;
-	u8 *buf = ap->ncq_sense_buf;
+	u8 *buf = dev->cdl->ncq_sense_log_buf;
 	struct ata_queued_cmd *qc;
 	unsigned int err_mask, tag;
 	u8 *sense, sk = 0, asc = 0, ascq = 0;

drivers/ata/libata-scsi.c

···
 static unsigned int ata_msense_control_spgt2(struct ata_device *dev, u8 *buf,
 					     u8 spg)
 {
-	u8 *b, *cdl = dev->cdl, *desc;
+	u8 *b, *cdl = dev->cdl->desc_log_buf, *desc;
 	u32 policy;
 	int i;
 

drivers/ata/libata.h

···
 extern const char *sata_spd_string(unsigned int spd);
 extern unsigned int ata_read_log_page(struct ata_device *dev, u8 log,
 				      u8 page, void *buf, unsigned int sectors);
+void ata_dev_cleanup_cdl_resources(struct ata_device *dev);
 
 #define to_ata_port(d) container_of(d, struct ata_port, tdev)
 

include/linux/libata.h

···
 	struct ata_cpr		cpr[] __counted_by(nr_cpr);
 };
 
+struct ata_cdl {
+	/*
+	 * Buffer to cache the CDL log page 18h (command duration descriptors)
+	 * for SCSI-ATA translation.
+	 */
+	u8			desc_log_buf[ATA_LOG_CDL_SIZE];
+
+	/*
+	 * Buffer to handle reading the sense data for successful NCQ Commands
+	 * log page for commands using a CDL with one of the limits policy set
+	 * to 0xD (successful completion with sense data available bit set).
+	 */
+	u8			ncq_sense_log_buf[ATA_LOG_SENSE_NCQ_SIZE];
+};
+
 struct ata_device {
 	struct ata_link		*link;
 	unsigned int		devno;		/* 0 or 1 */
···
 	/* Concurrent positioning ranges */
 	struct ata_cpr_log	*cpr_log;
 
-	/* Command Duration Limits log support */
-	u8			cdl[ATA_LOG_CDL_SIZE];
+	/* Command Duration Limits support */
+	struct ata_cdl		*cdl;
 
 	/* error history */
 	int			spdn_cnt;
···
 #ifdef CONFIG_ATA_ACPI
 	struct ata_acpi_gtm	__acpi_init_gtm; /* use ata_acpi_init_gtm() */
 #endif
-	/* owned by EH */
-	u8			*ncq_sense_buf;
 };
 
 /* The following initializer overrides a method to NULL whether one of