[PATCH v2 1/2] libata: Use scsi cmnd budget token for qc tag for SAS host

From: John Garry
Date: Mon Apr 04 2022 - 10:59:04 EST


For attaining a qc tag for a SAS host we need to allocate a bit in
ata_port.sas_tag_allocated bitmap.

However we already have a unique tag per device in range
[0, ATA_MAX_QUEUE) in the scsi cmnd budget token, so just use that
instead.

Signed-off-by: John Garry <john.garry@xxxxxxxxxx>
---
drivers/ata/libata-core.c | 14 +++++---------
drivers/ata/libata-sata.c | 25 ++++---------------------
drivers/ata/libata-scsi.c | 2 +-
drivers/ata/libata.h | 7 +++----
include/linux/libata.h | 1 -
5 files changed, 13 insertions(+), 36 deletions(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index cceedde51126..1067b2e2be28 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -4566,14 +4566,15 @@ void swap_buf_le16(u16 *buf, unsigned int buf_words)
/**
* ata_qc_new_init - Request an available ATA command, and initialize it
* @dev: Device from whom we request an available command structure
- * @tag: tag
+ * @scmd: scmd for which to get qc
*
* LOCKING:
* None.
*/

-struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev, int tag)
+struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev, struct scsi_cmnd *scmd)
{
+ int tag = scsi_cmd_to_rq(scmd)->tag;
struct ata_port *ap = dev->link->ap;
struct ata_queued_cmd *qc;

@@ -4583,7 +4584,7 @@ struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev, int tag)

/* libsas case */
if (ap->flags & ATA_FLAG_SAS_HOST) {
- tag = ata_sas_allocate_tag(ap);
+ tag = ata_sas_get_tag(scmd);
if (tag < 0)
return NULL;
}
@@ -4611,19 +4612,14 @@ struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev, int tag)
*/
void ata_qc_free(struct ata_queued_cmd *qc)
{
- struct ata_port *ap;
unsigned int tag;

WARN_ON_ONCE(qc == NULL); /* ata_qc_from_tag _might_ return NULL */
- ap = qc->ap;

qc->flags = 0;
tag = qc->tag;
- if (ata_tag_valid(tag)) {
+ if (ata_tag_valid(tag))
qc->tag = ATA_TAG_POISON;
- if (ap->flags & ATA_FLAG_SAS_HOST)
- ata_sas_free_tag(tag, ap);
- }
}

void __ata_qc_complete(struct ata_queued_cmd *qc)
diff --git a/drivers/ata/libata-sata.c b/drivers/ata/libata-sata.c
index 044a16daa2d4..c3e9fd7d920c 100644
--- a/drivers/ata/libata-sata.c
+++ b/drivers/ata/libata-sata.c
@@ -1268,29 +1268,12 @@ int ata_sas_queuecmd(struct scsi_cmnd *cmd, struct ata_port *ap)
}
EXPORT_SYMBOL_GPL(ata_sas_queuecmd);

-int ata_sas_allocate_tag(struct ata_port *ap)
+int ata_sas_get_tag(struct scsi_cmnd *scmd)
{
- unsigned int max_queue = ap->host->n_tags;
- unsigned int i, tag;
+ if (WARN_ON_ONCE(scmd->budget_token >= ATA_MAX_QUEUE))
+ return -1;

- for (i = 0, tag = ap->sas_last_tag + 1; i < max_queue; i++, tag++) {
- tag = tag < max_queue ? tag : 0;
-
- /* the last tag is reserved for internal command. */
- if (ata_tag_internal(tag))
- continue;
-
- if (!test_and_set_bit(tag, &ap->sas_tag_allocated)) {
- ap->sas_last_tag = tag;
- return tag;
- }
- }
- return -1;
-}
-
-void ata_sas_free_tag(unsigned int tag, struct ata_port *ap)
-{
- clear_bit(tag, &ap->sas_tag_allocated);
+ return scmd->budget_token;
}

/**
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 06c9d90238d9..61dd7f7c7743 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -640,7 +640,7 @@ static struct ata_queued_cmd *ata_scsi_qc_new(struct ata_device *dev,
{
struct ata_queued_cmd *qc;

- qc = ata_qc_new_init(dev, scsi_cmd_to_rq(cmd)->tag);
+ qc = ata_qc_new_init(dev, cmd);
if (qc) {
qc->scsicmd = cmd;
qc->scsidone = scsi_done;
diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h
index c9c2496d91ea..92e52090165b 100644
--- a/drivers/ata/libata.h
+++ b/drivers/ata/libata.h
@@ -44,7 +44,7 @@ static inline void ata_force_cbl(struct ata_port *ap) { }
#endif
extern u64 ata_tf_to_lba(const struct ata_taskfile *tf);
extern u64 ata_tf_to_lba48(const struct ata_taskfile *tf);
-extern struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev, int tag);
+extern struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev, struct scsi_cmnd *scmd);
extern int ata_build_rw_tf(struct ata_taskfile *tf, struct ata_device *dev,
u64 block, u32 n_block, unsigned int tf_flags,
unsigned int tag, int class);
@@ -93,10 +93,9 @@ extern unsigned int ata_read_log_page(struct ata_device *dev, u8 log,

/* libata-sata.c */
#ifdef CONFIG_SATA_HOST
-int ata_sas_allocate_tag(struct ata_port *ap);
-void ata_sas_free_tag(unsigned int tag, struct ata_port *ap);
+int ata_sas_get_tag(struct scsi_cmnd *scmd);
#else
-static inline int ata_sas_allocate_tag(struct ata_port *ap)
+static inline int ata_sas_get_tag(struct scsi_cmnd *scmd)
{
return -EOPNOTSUPP;
}
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 9b1d3d8b1252..16107122e587 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -820,7 +820,6 @@ struct ata_port {
unsigned int cbl; /* cable type; ATA_CBL_xxx */

struct ata_queued_cmd qcmd[ATA_MAX_QUEUE + 1];
- unsigned long sas_tag_allocated; /* for sas tag allocation only */
u64 qc_active;
int nr_active_links; /* #links with active qcs */
unsigned int sas_last_tag; /* track next tag hw expects */
--
2.26.2