On 29/09/2022 03:22, Damien Le Moal wrote:
On 9/28/22 21:27, 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 slot.
Unfortunately we don't support reserved commands in the SCSI midlayer yet.
As such, SMP tasks - as an example - will not have a request associated, so
in the interim continue to manage those tags for that type of sas_task
internally.
We reserve an arbitrary 4 tags for these internal tags. Indeed, we already
decrement MVS_RSVD_SLOTS by 2 for the shost can_queue when flag
MVF_FLAG_SOC is set. This change was made in commit 20b09c2992fef
("[PATCH] [SCSI] mvsas: add support for 94xx; layout change; bug fixes"),
but what those 2 slots are used for is not obvious.
Signed-off-by: John Garry <john.garry@xxxxxxxxxx>
---
drivers/scsi/mvsas/mv_defs.h | 1 +
drivers/scsi/mvsas/mv_init.c | 4 ++--
drivers/scsi/mvsas/mv_sas.c | 22 +++++++++++++++++-----
drivers/scsi/mvsas/mv_sas.h | 1 -
4 files changed, 20 insertions(+), 8 deletions(-)
diff --git a/drivers/scsi/mvsas/mv_defs.h b/drivers/scsi/mvsas/mv_defs.h
index 7123a2efbf58..8ef174cd4d37 100644
--- a/drivers/scsi/mvsas/mv_defs.h
+++ b/drivers/scsi/mvsas/mv_defs.h
@@ -40,6 +40,7 @@ enum driver_configuration {
MVS_ATA_CMD_SZ = 96, /* SATA command table buffer size */
MVS_OAF_SZ = 64, /* Open address frame buffer size */
MVS_QUEUE_SIZE = 64, /* Support Queue depth */
+ MVS_RSVD_SLOTS = 4,
MVS_SOC_CAN_QUEUE = MVS_SOC_SLOTS - 2,
};
diff --git a/drivers/scsi/mvsas/mv_init.c b/drivers/scsi/mvsas/mv_init.c
index c85fb812ad43..d834ed9e8e4a 100644
--- a/drivers/scsi/mvsas/mv_init.c
+++ b/drivers/scsi/mvsas/mv_init.c
@@ -284,7 +284,7 @@ static int mvs_alloc(struct mvs_info *mvi, struct Scsi_Host *shost)
printk(KERN_DEBUG "failed to create dma pool %s.\n", pool_name);
goto err_out;
}
- mvi->tags_num = slot_nr;
+ mvi->tags_num = MVS_RSVD_SLOTS;
Same comment as for pm8001: do you really need this field if the value
is always MVS_RSVD_SLOTS ?
Right, I don't need this struct member. Again I can just use this macro
directly.
return 0;
err_out:
@@ -367,7 +367,7 @@ static struct mvs_info *mvs_pci_alloc(struct pci_dev *pdev,
mvi->sas = sha;
mvi->shost = shost;
- mvi->tags = kzalloc(MVS_CHIP_SLOT_SZ>>3, GFP_KERNEL);
+ mvi->tags = kzalloc(MVS_RSVD_SLOTS, GFP_KERNEL);
Field name ? reserved_tags ?
Also, the alloc seems wrong. This will allocate 4 bytes, but you only
need 4 bits. You could make this an unsigned long and not allocate
anything.
Well spotted. I should have questioned more why they had >>3 previously.
But I would rather keep as a bitmap, i.e. *unsigned long for simplicity.
Same remark for pm8001 by the way.
I think it's ok as it uses bitmap_zalloc()
That would cap MVS_RSVD_SLOTS to BITS_PER_LONG maximum, but that is easy
to check at compile time with a #if/#error.
As above, I'd rather keep as a bitmap. It's a little inefficient, but is
a one off in the driver.
Thanks,
John
