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Subject: RE: Re: [PATCH v5 05/10] scsi: ufshpb: Region inactivation in host
 mode
Reply-To: daejun7.park@samsung.com
Sender: Daejun Park <daejun7.park@samsung.com>
From:   Daejun Park <daejun7.park@samsung.com>
To:     Can Guo <cang@codeaurora.org>,
        Daejun Park <daejun7.park@samsung.com>
CC:     Avri Altman <Avri.Altman@wdc.com>,
        "James E . J . Bottomley" <jejb@linux.vnet.ibm.com>,
        "Martin K . Petersen" <martin.petersen@oracle.com>,
        "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
        Bart Van Assche <bvanassche@acm.org>,
        yongmyung lee <ymhungry.lee@samsung.com>,
        ALIM AKHTAR <alim.akhtar@samsung.com>,
        "asutoshd@codeaurora.org" <asutoshd@codeaurora.org>,
        Zang Leigang <zangleigang@hisilicon.com>,
        Avi Shchislowski <Avi.Shchislowski@wdc.com>,
        Bean Huo <beanhuo@micron.com>,
        "stanley.chu@mediatek.com" <stanley.chu@mediatek.com>
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Date:   Wed, 17 Mar 2021 14:19:30 +0900
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References: <064483451ff0d9ef8703871332ea5c3b@codeaurora.org>
        <DM6PR04MB65751EE32D25C7E57A6BABE8FC6B9@DM6PR04MB6575.namprd04.prod.outlook.com>
        <20210302132503.224670-1-avri.altman@wdc.com>
        <20210302132503.224670-6-avri.altman@wdc.com>
        <25da7378d5bf4c52443ae9b47f3fd778@codeaurora.org>
        <57afb2b5d7edda61a40493d8545785b1@codeaurora.org>
        <2038148563.21615949282962.JavaMail.epsvc@epcpadp4>
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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);
>>>> >>
>>>> >> +    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;

I found this problem too. I fixed it and submit next patch.

if (blk_rq_is_scsi(cmd->request) ||
	    (!ufshpb_is_write_or_discard_cmd(cmd) &&
	    !ufshpb_is_read_cmd(cmd)))
		return 0;


Thanks,
Daejun

>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 {
>>> 
>>> 
>>> 
> 
> 
>