Re: [PATCH v2 4/6] scsi: pm8001: Use sas_task_find_rq() for tagging

From: Hannes Reinecke
Date: Tue Oct 04 2022 - 01:53:17 EST


On 9/30/22 10:56, John Garry wrote:
The request associated with a scsi command coming from the block layer
has a unique tag, so use that when possible for getting a CCB.

Unfortunately we don't support reserved commands in the SCSI midlayer yet,
so in the interim continue to manage those tags internally (along with
tags for private commands).

Signed-off-by: John Garry <john.garry@xxxxxxxxxx>
---
drivers/scsi/pm8001/pm8001_init.c | 12 ++++--------
drivers/scsi/pm8001/pm8001_sas.c | 16 ++++++++++++----
drivers/scsi/pm8001/pm8001_sas.h | 11 ++++++++---
drivers/scsi/pm8001/pm80xx_hwi.c | 17 +++--------------
4 files changed, 27 insertions(+), 29 deletions(-)

diff --git a/drivers/scsi/pm8001/pm8001_init.c b/drivers/scsi/pm8001/pm8001_init.c
index 0edc9857a8bd..abb884ddcaf9 100644
--- a/drivers/scsi/pm8001/pm8001_init.c
+++ b/drivers/scsi/pm8001/pm8001_init.c
@@ -196,7 +196,7 @@ static void pm8001_free(struct pm8001_hba_info *pm8001_ha)
}
PM8001_CHIP_DISP->chip_iounmap(pm8001_ha);
flush_workqueue(pm8001_wq);
- bitmap_free(pm8001_ha->tags);
+ bitmap_free(pm8001_ha->rsvd_tags);
kfree(pm8001_ha);
}
@@ -1208,18 +1208,15 @@ static int pm8001_init_ccb_tag(struct pm8001_hba_info *pm8001_ha)
struct Scsi_Host *shost = pm8001_ha->shost;
struct device *dev = pm8001_ha->dev;
u32 max_out_io, ccb_count;
- u32 can_queue;
int i;
max_out_io = pm8001_ha->main_cfg_tbl.pm80xx_tbl.max_out_io;
ccb_count = min_t(int, PM8001_MAX_CCB, max_out_io);
- /* Update to the scsi host*/
- can_queue = ccb_count - PM8001_RESERVE_SLOT;
- shost->can_queue = can_queue;
+ shost->can_queue = ccb_count - PM8001_RESERVE_SLOT;
- pm8001_ha->tags = bitmap_zalloc(ccb_count, GFP_KERNEL);
- if (!pm8001_ha->tags)
+ pm8001_ha->rsvd_tags = bitmap_zalloc(PM8001_RESERVE_SLOT, GFP_KERNEL);
+ if (!pm8001_ha->rsvd_tags)
goto err_out;
/* Memory region for ccb_info*/
@@ -1244,7 +1241,6 @@ static int pm8001_init_ccb_tag(struct pm8001_hba_info *pm8001_ha)
pm8001_ha->ccb_info[i].task = NULL;
pm8001_ha->ccb_info[i].ccb_tag = PM8001_INVALID_TAG;
pm8001_ha->ccb_info[i].device = NULL;
- ++pm8001_ha->tags_num;
}
return 0;
diff --git a/drivers/scsi/pm8001/pm8001_sas.c b/drivers/scsi/pm8001/pm8001_sas.c
index 066dfa9f4683..d60bc311a4e9 100644
--- a/drivers/scsi/pm8001/pm8001_sas.c
+++ b/drivers/scsi/pm8001/pm8001_sas.c
@@ -65,9 +65,14 @@ static int pm8001_find_tag(struct sas_task *task, u32 *tag)
*/
void pm8001_tag_free(struct pm8001_hba_info *pm8001_ha, u32 tag)
{
- void *bitmap = pm8001_ha->tags;
+ void *bitmap = pm8001_ha->rsvd_tags;
unsigned long flags;
+ if (tag < pm8001_ha->shost->can_queue)
+ return;
+
+ tag -= pm8001_ha->shost->can_queue;
+
spin_lock_irqsave(&pm8001_ha->bitmap_lock, flags);
__clear_bit(tag, bitmap);
spin_unlock_irqrestore(&pm8001_ha->bitmap_lock, flags);
@@ -80,18 +85,21 @@ void pm8001_tag_free(struct pm8001_hba_info *pm8001_ha, u32 tag)
*/
int pm8001_tag_alloc(struct pm8001_hba_info *pm8001_ha, u32 *tag_out)
{
- void *bitmap = pm8001_ha->tags;
+ void *bitmap = pm8001_ha->rsvd_tags;
unsigned long flags;
unsigned int tag;
spin_lock_irqsave(&pm8001_ha->bitmap_lock, flags);
- tag = find_first_zero_bit(bitmap, pm8001_ha->tags_num);
- if (tag >= pm8001_ha->tags_num) {
+ tag = find_first_zero_bit(bitmap, PM8001_RESERVE_SLOT);
+ if (tag >= PM8001_RESERVE_SLOT) {
spin_unlock_irqrestore(&pm8001_ha->bitmap_lock, flags);
return -SAS_QUEUE_FULL;
}
__set_bit(tag, bitmap);
spin_unlock_irqrestore(&pm8001_ha->bitmap_lock, flags);
+
+ /* reserved tags are in the upper region of the tagset */
+ tag += pm8001_ha->shost->can_queue;
*tag_out = tag;
return 0;
}
Can you move the reserved tags to the _lower_ region of the tagset?
That way the tag allocation scheme matches with what the block-layer does, and the eventual conversion to reserved tags becomes easier.

Cheers,

Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@xxxxxxx +49 911 74053 688
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