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

[Can Guo]

On 2021-03-17 10:28, Daejun Park wrote:
> > > >> ---
> > > >>  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);
> > > >>
> > > >> +    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(),
> > > > 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

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.

> Thanks,
> Daejun
>
>
> > Thanks,
> > Avri
> >
> > > Can Guo.
> > >
> > > > Thanks.
> > > > Can Guo.
> > > >
> > > >> +            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[] =
> > > >> {
> > > >>      &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 {