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 <dlemoal@kernel.org>
Reviewed-by: Niklas Cassel <cassel@kernel.org>

1 files changed, 17 insertions, 4 deletions

diff --git a/include/linux/libata.h b/include/linux/libata.h
index aac38dcd2230..9b4a6ff03235 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -700,6 +700,21 @@ struct ata_cpr_log {
 	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 */
@@ -762,8 +777,8 @@ struct ata_device {
 	/* 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;
@@ -917,8 +932,6 @@ struct ata_port {
 #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