RE: [PATCH v5 05/10] scsi: ufshpb: Region inactivation in host mode

On 2021-03-17 10:28, Daejun Park wrote:

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---
 drivers/scsi/ufs/ufshpb.c | 14 ++++++++++++++
 drivers/scsi/ufs/ufshpb.h |  1 +
 2 files changed, 15 insertions(+)

diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
index 6f4fd22eaf2f..0744feb4d484 100644
--- a/drivers/scsi/ufs/ufshpb.c
+++ b/drivers/scsi/ufs/ufshpb.c

@@ -907,6 +907,7 @@ static int ufshpb_execute_umap_req(struct

ufshpb_lu *hpb,

     blk_execute_rq_nowait(q, NULL, req, 1,

ufshpb_umap_req_compl_fn);

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+    hpb->stats.umap_req_cnt++;
     return 0;
 }

@@ -1103,6 +1104,12 @@ static int ufshpb_issue_umap_req(struct

ufshpb_lu *hpb,
     return -EAGAIN;
 }

+static int ufshpb_issue_umap_single_req(struct ufshpb_lu *hpb,
+                                    struct ufshpb_region *rgn)
+{
+    return ufshpb_issue_umap_req(hpb, rgn);
+}
+
 static int ufshpb_issue_umap_all_req(struct ufshpb_lu *hpb)
 {
     return ufshpb_issue_umap_req(hpb, NULL);

@@ -1115,6 +1122,10 @@ static void __ufshpb_evict_region(struct

ufshpb_lu *hpb,
     struct ufshpb_subregion *srgn;
     int srgn_idx;

+
+    if (hpb->is_hcm && ufshpb_issue_umap_single_req(hpb, rgn))

__ufshpb_evict_region() is called with rgn_state_lock held and IRQ
disabled,
when ufshpb_issue_umap_single_req() invokes

blk_execute_rq_nowait(),

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below
warning shall pop up every time, fix it?

void blk_execute_rq_nowait(struct request_queue *q, struct gendisk
*bd_disk,
                 struct request *rq, int at_head,
                         rq_end_io_fn *done)
{
      WARN_ON(irqs_disabled());
...

Moreover, since we are here with rgn_state_lock held and IRQ
disabled,
in ufshpb_get_req(), rq = kmem_cache_alloc(hpb->map_req_cache,
GFP_KERNEL)
has the GFP_KERNEL flag, scheduling while atomic???

I think your comment applies to  ufshpb_issue_umap_all_req as well,
Which is called from slave_configure/scsi_add_lun.

Since the host-mode series is utilizing the framework laid by the
device-mode,
Maybe you can add this comment to  Daejun's last version?

Hi Avri, Can Guo

I think ufshpb_issue_umap_single_req() can be moved to end of
ufshpb_evict_region().
Then we can avoid rgn_state_lock when it sends unmap command.

I am not the expert here, please you two fix it. I am just reporting
what can be wrong. Anyways, ufshpb_issue_umap_single_req() should not
be called with rgn_state_lock held - think about below (another deadly)
scenario.

lock(rgn_state_lock)
   ufshpb_issue_umap_single_req()
     ufshpb_prep()
        lock(rgn_state_lock)   <---------- recursive spin_lock

Will fix.   Will wait for Daejun's v30 to see if anything applies to unmap_single.

Thanks,
Avri 

BTW, @Daejun shouldn't we stop passthrough cmds from stepping
into ufshpb_prep()? In current code, you are trying to use below
check to block cmds other than write/discard/read, but a passthrough
cmd can not be blocked by the check.

          if (!ufshpb_is_write_or_discard_cmd(cmd) &&
              !ufshpb_is_read_cmd(cmd))
                  return 0;

Thanks,
Can Guo.

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Thanks,
Daejun

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Thanks,
Avri

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Can Guo.

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Thanks.
Can Guo.

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+            return;
+
     lru_info = &hpb->lru_info;

     dev_dbg(&hpb->sdev_ufs_lu->sdev_dev, "evict region %d\n",
rgn->rgn_idx);

@@ -1855,6 +1866,7 @@ ufshpb_sysfs_attr_show_func(rb_noti_cnt);
 ufshpb_sysfs_attr_show_func(rb_active_cnt);
 ufshpb_sysfs_attr_show_func(rb_inactive_cnt);
 ufshpb_sysfs_attr_show_func(map_req_cnt);
+ufshpb_sysfs_attr_show_func(umap_req_cnt);

 static struct attribute *hpb_dev_stat_attrs[] = {
     &dev_attr_hit_cnt.attr,

@@ -1863,6 +1875,7 @@ static struct attribute *hpb_dev_stat_attrs[]

=

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{
     &dev_attr_rb_active_cnt.attr,
     &dev_attr_rb_inactive_cnt.attr,
     &dev_attr_map_req_cnt.attr,
+    &dev_attr_umap_req_cnt.attr,
     NULL,
 };

@@ -1978,6 +1991,7 @@ static void ufshpb_stat_init(struct ufshpb_lu

*hpb)
     hpb->stats.rb_active_cnt = 0;
     hpb->stats.rb_inactive_cnt = 0;
     hpb->stats.map_req_cnt = 0;
+    hpb->stats.umap_req_cnt = 0;
 }

 static void ufshpb_param_init(struct ufshpb_lu *hpb)

diff --git a/drivers/scsi/ufs/ufshpb.h b/drivers/scsi/ufs/ufshpb.h
index bd4308010466..84598a317897 100644
--- a/drivers/scsi/ufs/ufshpb.h
+++ b/drivers/scsi/ufs/ufshpb.h

@@ -186,6 +186,7 @@ struct ufshpb_stats {
     u64 rb_inactive_cnt;
     u64 map_req_cnt;
     u64 pre_req_cnt;
+    u64 umap_req_cnt;
 };

 struct ufshpb_lu {