linux-kernel - RE: [PATCH v11 08/12] scsi: ufshpb: Add "Cold" regions timer

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Date:   Mon, 21 Jun 2021 07:03:04 +0000
From:   Avri Altman <Avri.Altman@....com>
To:     "daejun7.park@...sung.com" <daejun7.park@...sung.com>,
        "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>
CC:     "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>,
        "cang@...eaurora.org" <cang@...eaurora.org>,
        "stanley.chu@...iatek.com" <stanley.chu@...iatek.com>
Subject: RE: [PATCH v11 08/12] scsi: ufshpb: Add "Cold" regions timer


> Hi Avri,
> 
> >diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
> >index 39b86e8b2eee..cf719831adb3 100644
> >--- a/drivers/scsi/ufs/ufshpb.c
> >+++ b/drivers/scsi/ufs/ufshpb.c
> 
> ...
> 
> >+static void ufshpb_read_to_handler(struct work_struct *work)
> >+{
> >+        struct ufshpb_lu *hpb = container_of(work, struct ufshpb_lu,
> >+                                             ufshpb_read_to_work.work);
> >+        struct victim_select_info *lru_info = &hpb->lru_info;
> >+        struct ufshpb_region *rgn, *next_rgn;
> >+        unsigned long flags;
> >+        LIST_HEAD(expired_list);
> >+
> >+        if (test_and_set_bit(TIMEOUT_WORK_RUNNING, &hpb-
> >work_data_bits))
> >+                return;
> >+
> >+        spin_lock_irqsave(&hpb->rgn_state_lock, flags);
> >+
> >+        list_for_each_entry_safe(rgn, next_rgn, &lru_info->lh_lru_rgn,
> >+                                 list_lru_rgn) {
> >+                bool timedout = ktime_after(ktime_get(), rgn->read_timeout);
> >+
> >+                if (timedout) {
> >+                        rgn->read_timeout_expiries--;
> >+                        if (is_rgn_dirty(rgn) ||
> >+                            rgn->read_timeout_expiries == 0)
> >+                                list_add(&rgn->list_expired_rgn, &expired_list);
> 
> Why we need additional expired_list for updating inactive information?
Since the lru list is accessed under rgn_state_lock, 
and inactivation is done under rsp_list_lock,
It's just a convenient way to list all the expired  regions.

> And I think "rgn->list_lru_rgn" should be deleted when it is expired.
Oh - I don't think so.
This should be done in one place only, which is cleanup_lru_info,
Which is called, in host mode, after a successful unmap request.

Thanks,
Avri

> 
> >+                        else
> >+                                rgn->read_timeout = ktime_add_ms(ktime_get(),
> >+                                                         READ_TO_MS);
> >+                }
> >+        }
> >+
> >+        spin_unlock_irqrestore(&hpb->rgn_state_lock, flags);
> >+
> >+        list_for_each_entry_safe(rgn, next_rgn, &expired_list,
> >+                                 list_expired_rgn) {
> >+                list_del_init(&rgn->list_expired_rgn);
> >+                spin_lock_irqsave(&hpb->rsp_list_lock, flags);
> >+                ufshpb_update_inactive_info(hpb, rgn->rgn_idx);
> >+                spin_unlock_irqrestore(&hpb->rsp_list_lock, flags);
> >+        }
> >+
> >+        ufshpb_kick_map_work(hpb);
> >+
> >+        clear_bit(TIMEOUT_WORK_RUNNING, &hpb->work_data_bits);
> >+
> >+        schedule_delayed_work(&hpb->ufshpb_read_to_work,
> >+                              msecs_to_jiffies(POLLING_INTERVAL_MS));
> >+}
> >+
> 
> Thanks,
> Daejun