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Date: Wed, 17 Mar 2021 07:59:42 +0000
From: Avri Altman <Avri.Altman@....com>
To: Can Guo <cang@...eaurora.org>,
"daejun7.park@...sung.com" <daejun7.park@...sung.com>
CC: "James E . J . Bottomley" <jejb@...ux.vnet.ibm.com>,
"Martin K . Petersen" <martin.petersen@...cle.com>,
"linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
Bart Van Assche <bvanassche@....org>,
yongmyung lee <ymhungry.lee@...sung.com>,
ALIM AKHTAR <alim.akhtar@...sung.com>,
"asutoshd@...eaurora.org" <asutoshd@...eaurora.org>,
Zang Leigang <zangleigang@...ilicon.com>,
Avi Shchislowski <Avi.Shchislowski@....com>,
Bean Huo <beanhuo@...ron.com>,
"stanley.chu@...iatek.com" <stanley.chu@...iatek.com>
Subject: RE: [PATCH v5 05/10] scsi: ufshpb: Region inactivation in host mode
> 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
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.
>
> >
> > 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 {
> >>
> >>
> >>
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