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

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Date:   Wed, 17 Mar 2021 09:23:47 +0800
From:   Can Guo <cang@...eaurora.org>
To:     Avri Altman <Avri.Altman@....com>
Cc:     "James E . J . Bottomley" <jejb@...ux.vnet.ibm.com>,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
        gregkh@...uxfoundation.org, Bart Van Assche <bvanassche@....org>,
        yongmyung lee <ymhungry.lee@...sung.com>,
        Daejun Park <daejun7.park@...sung.com>,
        alim.akhtar@...sung.com, asutoshd@...eaurora.org,
        Zang Leigang <zangleigang@...ilicon.com>,
        Avi Shchislowski <Avi.Shchislowski@....com>,
        Bean Huo <beanhuo@...ron.com>, stanley.chu@...iatek.com
Subject: Re: [PATCH v5 05/10] scsi: ufshpb: Region inactivation in host mode

On 2021-03-16 16:30, Avri Altman 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.

ufshpb_issue_umap_all_req() is not called from atomic contexts,
so ufshpb_issue_umap_all_req() is fine.

Thanks,
Can Guo.

> 
> 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?
> 
> 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 {