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    SubjectRe: [PATCH v3 5/7] scsi: pm8001: Use sas_task_find_rq() for tagging
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    On 10/4/22 20:27, 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@huawei.com>
    > Reviewed-by: Jack Wang <jinpu.wang@ionos.com>

    Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>

    (see the end for a nit)

    > ---
    > drivers/scsi/pm8001/pm8001_init.c | 12 ++++--------
    > drivers/scsi/pm8001/pm8001_sas.c | 13 +++++++++----
    > drivers/scsi/pm8001/pm8001_sas.h | 11 ++++++++---
    > drivers/scsi/pm8001/pm80xx_hwi.c | 17 +++--------------
    > 4 files changed, 24 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..f46588cd5c73 100644
    > --- a/drivers/scsi/pm8001/pm8001_sas.c
    > +++ b/drivers/scsi/pm8001/pm8001_sas.c
    > @@ -65,9 +65,12 @@ 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_RESERVE_SLOT)
    > + return;
    > +
    > spin_lock_irqsave(&pm8001_ha->bitmap_lock, flags);
    > __clear_bit(tag, bitmap);
    > spin_unlock_irqrestore(&pm8001_ha->bitmap_lock, flags);
    > @@ -80,18 +83,20 @@ 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 lower region of the tagset */
    > *tag_out = tag;
    > return 0;
    > }
    > diff --git a/drivers/scsi/pm8001/pm8001_sas.h b/drivers/scsi/pm8001/pm8001_sas.h
    > index 9acaadf02150..b584e68664d8 100644
    > --- a/drivers/scsi/pm8001/pm8001_sas.h
    > +++ b/drivers/scsi/pm8001/pm8001_sas.h
    > @@ -510,8 +510,7 @@ struct pm8001_hba_info {
    > u32 chip_id;
    > const struct pm8001_chip_info *chip;
    > struct completion *nvmd_completion;
    > - int tags_num;
    > - unsigned long *tags;
    > + unsigned long *rsvd_tags;
    > struct pm8001_phy phy[PM8001_MAX_PHYS];
    > struct pm8001_port port[PM8001_MAX_PHYS];
    > u32 id;
    > @@ -737,9 +736,15 @@ pm8001_ccb_alloc(struct pm8001_hba_info *pm8001_ha,
    > struct pm8001_device *dev, struct sas_task *task)
    > {
    > struct pm8001_ccb_info *ccb;
    > + struct request *rq = NULL;
    > u32 tag;
    >
    > - if (pm8001_tag_alloc(pm8001_ha, &tag)) {
    > + if (task)
    > + rq = sas_task_find_rq(task);
    > +
    > + if (rq) {
    > + tag = rq->tag + PM8001_RESERVE_SLOT;
    > + } else if (pm8001_tag_alloc(pm8001_ha, &tag)) {
    > pm8001_dbg(pm8001_ha, FAIL, "Failed to allocate a tag\n");
    > return NULL;
    > }
    > diff --git a/drivers/scsi/pm8001/pm80xx_hwi.c b/drivers/scsi/pm8001/pm80xx_hwi.c
    > index 4484c498bcb6..ed2d65d3749a 100644
    > --- a/drivers/scsi/pm8001/pm80xx_hwi.c
    > +++ b/drivers/scsi/pm8001/pm80xx_hwi.c
    > @@ -4247,24 +4247,13 @@ static int check_enc_sat_cmd(struct sas_task *task)
    >
    > static u32 pm80xx_chip_get_q_index(struct sas_task *task)
    > {
    > - struct scsi_cmnd *scmd = NULL;
    > + struct request *rq = sas_task_find_rq(task);
    > u32 blk_tag;
    >
    > - if (task->uldd_task) {
    > - struct ata_queued_cmd *qc;
    > -
    > - if (dev_is_sata(task->dev)) {
    > - qc = task->uldd_task;
    > - scmd = qc->scsicmd;
    > - } else {
    > - scmd = task->uldd_task;
    > - }
    > - }
    > -
    > - if (!scmd)
    > + if (!rq)
    > return 0;
    >
    > - blk_tag = blk_mq_unique_tag(scsi_cmd_to_rq(scmd));
    > + blk_tag = blk_mq_unique_tag(rq);
    > return blk_mq_unique_tag_to_hwq(blk_tag);

    Nit: You could simplify:

    return blk_mq_unique_tag_to_hwq(blk_mq_unique_tag(rq));

    No need for blk_tag variable I think.

    > }
    >

    --
    Damien Le Moal
    Western Digital Research

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