[v5,07/10] scsi: ufshpb: Add "Cold" regions timer
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Message ID 20210302132503.224670-8-avri.altman@wdc.com
State New, archived
Headers show
Series
  • Add Host control mode to HPB
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Commit Message

Avri Altman March 2, 2021, 1:25 p.m. UTC
In order not to hang on to “cold” regions, we shall inactivate a
region that has no READ access for a predefined amount of time -
READ_TO_MS. For that purpose we shall monitor the active regions list,
polling it on every POLLING_INTERVAL_MS. On timeout expiry we shall add
the region to the "to-be-inactivated" list, unless it is clean and did
not exhaust its READ_TO_EXPIRIES - another parameter.

All this does not apply to pinned regions.

Signed-off-by: Avri Altman <avri.altman@wdc.com>
---
 drivers/scsi/ufs/ufshpb.c | 65 +++++++++++++++++++++++++++++++++++++++
 drivers/scsi/ufs/ufshpb.h |  6 ++++
 2 files changed, 71 insertions(+)

Comments

Can Guo March 15, 2021, 1:37 a.m. UTC | #1
On 2021-03-02 21:25, Avri Altman wrote:
> In order not to hang on to “cold” regions, we shall inactivate a
> region that has no READ access for a predefined amount of time -
> READ_TO_MS. For that purpose we shall monitor the active regions list,
> polling it on every POLLING_INTERVAL_MS. On timeout expiry we shall add
> the region to the "to-be-inactivated" list, unless it is clean and did
> not exhaust its READ_TO_EXPIRIES - another parameter.
> 
> All this does not apply to pinned regions.
> 
> Signed-off-by: Avri Altman <avri.altman@wdc.com>
> ---
>  drivers/scsi/ufs/ufshpb.c | 65 +++++++++++++++++++++++++++++++++++++++
>  drivers/scsi/ufs/ufshpb.h |  6 ++++
>  2 files changed, 71 insertions(+)
> 
> diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
> index 0034fa03fdc6..89a930e72cff 100644
> --- a/drivers/scsi/ufs/ufshpb.c
> +++ b/drivers/scsi/ufs/ufshpb.c
> @@ -18,6 +18,9 @@
> 
>  #define ACTIVATION_THRESHOLD 4 /* 4 IOs */
>  #define EVICTION_THRESHOLD (ACTIVATION_THRESHOLD << 6) /* 256 IOs */
> +#define READ_TO_MS 1000
> +#define READ_TO_EXPIRIES 100
> +#define POLLING_INTERVAL_MS 200
> 
>  /* memory management */
>  static struct kmem_cache *ufshpb_mctx_cache;
> @@ -1024,12 +1027,61 @@ static int
> ufshpb_check_srgns_issue_state(struct ufshpb_lu *hpb,
>  	return 0;
>  }
> 
> +static void ufshpb_read_to_handler(struct work_struct *work)
> +{
> +	struct delayed_work *dwork = to_delayed_work(work);
> +	struct ufshpb_lu *hpb;

         struct ufshpb_lu *hpb = container_of(work, struct ufshpb_lu, 
ufshpb_read_to_work.work);

usually we use this to get data of a delayed work.

> +	struct victim_select_info *lru_info;

         struct victim_select_info *lru_info = &hpb->lru_info;

This can save some lines.

Thanks,
Can Guo.

> +	struct ufshpb_region *rgn;
> +	unsigned long flags;
> +	LIST_HEAD(expired_list);
> +
> +	spin_lock_irqsave(&hpb->rgn_state_lock, flags);
> +
> +	list_for_each_entry(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);
> +			else
> +				rgn->read_timeout = ktime_add_ms(ktime_get(),
> +							 READ_TO_MS);
> +		}
> +	}
> +
> +	spin_unlock_irqrestore(&hpb->rgn_state_lock, flags);
> +
> +	list_for_each_entry(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);
> +		hpb->stats.rb_inactive_cnt++;
> +		spin_unlock_irqrestore(&hpb->rsp_list_lock, flags);
> +	}
> +
> +	ufshpb_kick_map_work(hpb);
> +
> +	schedule_delayed_work(&hpb->ufshpb_read_to_work,
> +			      msecs_to_jiffies(POLLING_INTERVAL_MS));
> +}
> +
>  static void ufshpb_add_lru_info(struct victim_select_info *lru_info,
>  				struct ufshpb_region *rgn)
>  {
>  	rgn->rgn_state = HPB_RGN_ACTIVE;
>  	list_add_tail(&rgn->list_lru_rgn, &lru_info->lh_lru_rgn);
>  	atomic_inc(&lru_info->active_cnt);
> +	if (rgn->hpb->is_hcm) {
> +		rgn->read_timeout = ktime_add_ms(ktime_get(), READ_TO_MS);
> +		rgn->read_timeout_expiries = READ_TO_EXPIRIES;
> +	}
>  }
> 
>  static void ufshpb_hit_lru_info(struct victim_select_info *lru_info,
> @@ -1813,6 +1865,7 @@ static int ufshpb_alloc_region_tbl(struct
> ufs_hba *hba, struct ufshpb_lu *hpb)
> 
>  		INIT_LIST_HEAD(&rgn->list_inact_rgn);
>  		INIT_LIST_HEAD(&rgn->list_lru_rgn);
> +		INIT_LIST_HEAD(&rgn->list_expired_rgn);
> 
>  		if (rgn_idx == hpb->rgns_per_lu - 1) {
>  			srgn_cnt = ((hpb->srgns_per_lu - 1) %
> @@ -1834,6 +1887,7 @@ static int ufshpb_alloc_region_tbl(struct
> ufs_hba *hba, struct ufshpb_lu *hpb)
>  		}
> 
>  		rgn->rgn_flags = 0;
> +		rgn->hpb = hpb;
>  	}
> 
>  	return 0;
> @@ -2053,6 +2107,8 @@ static int ufshpb_lu_hpb_init(struct ufs_hba
> *hba, struct ufshpb_lu *hpb)
>  			  ufshpb_normalization_work_handler);
>  		INIT_WORK(&hpb->ufshpb_lun_reset_work,
>  			  ufshpb_reset_work_handler);
> +		INIT_DELAYED_WORK(&hpb->ufshpb_read_to_work,
> +				  ufshpb_read_to_handler);
>  	}
> 
>  	hpb->map_req_cache = kmem_cache_create("ufshpb_req_cache",
> @@ -2087,6 +2143,10 @@ static int ufshpb_lu_hpb_init(struct ufs_hba
> *hba, struct ufshpb_lu *hpb)
>  	ufshpb_stat_init(hpb);
>  	ufshpb_param_init(hpb);
> 
> +	if (hpb->is_hcm)
> +		schedule_delayed_work(&hpb->ufshpb_read_to_work,
> +				      msecs_to_jiffies(POLLING_INTERVAL_MS));
> +
>  	return 0;
> 
>  release_pre_req_mempool:
> @@ -2154,6 +2214,7 @@ static void ufshpb_discard_rsp_lists(struct
> ufshpb_lu *hpb)
>  static void ufshpb_cancel_jobs(struct ufshpb_lu *hpb)
>  {
>  	if (hpb->is_hcm) {
> +		cancel_delayed_work_sync(&hpb->ufshpb_read_to_work);
>  		cancel_work_sync(&hpb->ufshpb_lun_reset_work);
>  		cancel_work_sync(&hpb->ufshpb_normalization_work);
>  	}
> @@ -2264,6 +2325,10 @@ void ufshpb_resume(struct ufs_hba *hba)
>  			continue;
>  		ufshpb_set_state(hpb, HPB_PRESENT);
>  		ufshpb_kick_map_work(hpb);
> +		if (hpb->is_hcm)
> +			schedule_delayed_work(&hpb->ufshpb_read_to_work,
> +				msecs_to_jiffies(POLLING_INTERVAL_MS));
> +
>  	}
>  }
> 
> diff --git a/drivers/scsi/ufs/ufshpb.h b/drivers/scsi/ufs/ufshpb.h
> index 37c1b0ea0c0a..b49e9a34267f 100644
> --- a/drivers/scsi/ufs/ufshpb.h
> +++ b/drivers/scsi/ufs/ufshpb.h
> @@ -109,6 +109,7 @@ struct ufshpb_subregion {
>  };
> 
>  struct ufshpb_region {
> +	struct ufshpb_lu *hpb;
>  	struct ufshpb_subregion *srgn_tbl;
>  	enum HPB_RGN_STATE rgn_state;
>  	int rgn_idx;
> @@ -126,6 +127,10 @@ struct ufshpb_region {
>  	/* region reads - for host mode */
>  	spinlock_t rgn_lock;
>  	unsigned int reads;
> +	/* region "cold" timer - for host mode */
> +	ktime_t read_timeout;
> +	unsigned int read_timeout_expiries;
> +	struct list_head list_expired_rgn;
>  };
> 
>  #define for_each_sub_region(rgn, i, srgn)				\
> @@ -219,6 +224,7 @@ struct ufshpb_lu {
>  	struct victim_select_info lru_info;
>  	struct work_struct ufshpb_normalization_work;
>  	struct work_struct ufshpb_lun_reset_work;
> +	struct delayed_work ufshpb_read_to_work;
> 
>  	/* pinned region information */
>  	u32 lu_pinned_start;
Avri Altman March 15, 2021, 7:54 a.m. UTC | #2
> >
> > +static void ufshpb_read_to_handler(struct work_struct *work)
> > +{
> > +     struct delayed_work *dwork = to_delayed_work(work);
> > +     struct ufshpb_lu *hpb;
> 
>          struct ufshpb_lu *hpb = container_of(work, struct ufshpb_lu,
> ufshpb_read_to_work.work);
> 
> usually we use this to get data of a delayed work.
> 
> > +     struct victim_select_info *lru_info;
> 
>          struct victim_select_info *lru_info = &hpb->lru_info;
> 
> This can save some lines.
Done.

Thanks,
Avri

> Thanks,
> Can Guo.
> 
> > +     struct ufshpb_region *rgn;
> > +     unsigned long flags;
> > +     LIST_HEAD(expired_list);
Can Guo March 15, 2021, 9:36 a.m. UTC | #3
On 2021-03-02 21:25, Avri Altman wrote:
> In order not to hang on to “cold” regions, we shall inactivate a
> region that has no READ access for a predefined amount of time -
> READ_TO_MS. For that purpose we shall monitor the active regions list,
> polling it on every POLLING_INTERVAL_MS. On timeout expiry we shall add
> the region to the "to-be-inactivated" list, unless it is clean and did
> not exhaust its READ_TO_EXPIRIES - another parameter.
> 
> All this does not apply to pinned regions.
> 
> Signed-off-by: Avri Altman <avri.altman@wdc.com>
> ---
>  drivers/scsi/ufs/ufshpb.c | 65 +++++++++++++++++++++++++++++++++++++++
>  drivers/scsi/ufs/ufshpb.h |  6 ++++
>  2 files changed, 71 insertions(+)
> 
> diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
> index 0034fa03fdc6..89a930e72cff 100644
> --- a/drivers/scsi/ufs/ufshpb.c
> +++ b/drivers/scsi/ufs/ufshpb.c
> @@ -18,6 +18,9 @@
> 
>  #define ACTIVATION_THRESHOLD 4 /* 4 IOs */
>  #define EVICTION_THRESHOLD (ACTIVATION_THRESHOLD << 6) /* 256 IOs */
> +#define READ_TO_MS 1000
> +#define READ_TO_EXPIRIES 100
> +#define POLLING_INTERVAL_MS 200
> 
>  /* memory management */
>  static struct kmem_cache *ufshpb_mctx_cache;
> @@ -1024,12 +1027,61 @@ static int
> ufshpb_check_srgns_issue_state(struct ufshpb_lu *hpb,
>  	return 0;
>  }
> 
> +static void ufshpb_read_to_handler(struct work_struct *work)
> +{
> +	struct delayed_work *dwork = to_delayed_work(work);
> +	struct ufshpb_lu *hpb;
> +	struct victim_select_info *lru_info;
> +	struct ufshpb_region *rgn;
> +	unsigned long flags;
> +	LIST_HEAD(expired_list);
> +
> +	hpb = container_of(dwork, struct ufshpb_lu, ufshpb_read_to_work);
> +
> +	spin_lock_irqsave(&hpb->rgn_state_lock, flags);
> +
> +	lru_info = &hpb->lru_info;
> +
> +	list_for_each_entry(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);
> +			else
> +				rgn->read_timeout = ktime_add_ms(ktime_get(),
> +							 READ_TO_MS);
> +		}
> +	}
> +
> +	spin_unlock_irqrestore(&hpb->rgn_state_lock, flags);
> +
> +	list_for_each_entry(rgn, &expired_list, list_expired_rgn) {

Here can be problematic - since you don't have the native expired_list 
initialized
before use, if above loop did not insert anything to expired_list, it 
shall become
a dead loop here.

And, which lock is protecting rgn->list_expired_rgn? If two 
read_to_handler works
are running in parallel, one can be inserting it to its expired_list 
while another
can be deleting it.

Can Guo.

> +		list_del_init(&rgn->list_expired_rgn);
> +		spin_lock_irqsave(&hpb->rsp_list_lock, flags);
> +		ufshpb_update_inactive_info(hpb, rgn->rgn_idx);
> +		hpb->stats.rb_inactive_cnt++;
> +		spin_unlock_irqrestore(&hpb->rsp_list_lock, flags);
> +	}
> +
> +	ufshpb_kick_map_work(hpb);
> +
> +	schedule_delayed_work(&hpb->ufshpb_read_to_work,
> +			      msecs_to_jiffies(POLLING_INTERVAL_MS));
> +}
> +
>  static void ufshpb_add_lru_info(struct victim_select_info *lru_info,
>  				struct ufshpb_region *rgn)
>  {
>  	rgn->rgn_state = HPB_RGN_ACTIVE;
>  	list_add_tail(&rgn->list_lru_rgn, &lru_info->lh_lru_rgn);
>  	atomic_inc(&lru_info->active_cnt);
> +	if (rgn->hpb->is_hcm) {
> +		rgn->read_timeout = ktime_add_ms(ktime_get(), READ_TO_MS);
> +		rgn->read_timeout_expiries = READ_TO_EXPIRIES;
> +	}
>  }
> 
>  static void ufshpb_hit_lru_info(struct victim_select_info *lru_info,
> @@ -1813,6 +1865,7 @@ static int ufshpb_alloc_region_tbl(struct
> ufs_hba *hba, struct ufshpb_lu *hpb)
> 
>  		INIT_LIST_HEAD(&rgn->list_inact_rgn);
>  		INIT_LIST_HEAD(&rgn->list_lru_rgn);
> +		INIT_LIST_HEAD(&rgn->list_expired_rgn);
> 
>  		if (rgn_idx == hpb->rgns_per_lu - 1) {
>  			srgn_cnt = ((hpb->srgns_per_lu - 1) %
> @@ -1834,6 +1887,7 @@ static int ufshpb_alloc_region_tbl(struct
> ufs_hba *hba, struct ufshpb_lu *hpb)
>  		}
> 
>  		rgn->rgn_flags = 0;
> +		rgn->hpb = hpb;
>  	}
> 
>  	return 0;
> @@ -2053,6 +2107,8 @@ static int ufshpb_lu_hpb_init(struct ufs_hba
> *hba, struct ufshpb_lu *hpb)
>  			  ufshpb_normalization_work_handler);
>  		INIT_WORK(&hpb->ufshpb_lun_reset_work,
>  			  ufshpb_reset_work_handler);
> +		INIT_DELAYED_WORK(&hpb->ufshpb_read_to_work,
> +				  ufshpb_read_to_handler);
>  	}
> 
>  	hpb->map_req_cache = kmem_cache_create("ufshpb_req_cache",
> @@ -2087,6 +2143,10 @@ static int ufshpb_lu_hpb_init(struct ufs_hba
> *hba, struct ufshpb_lu *hpb)
>  	ufshpb_stat_init(hpb);
>  	ufshpb_param_init(hpb);
> 
> +	if (hpb->is_hcm)
> +		schedule_delayed_work(&hpb->ufshpb_read_to_work,
> +				      msecs_to_jiffies(POLLING_INTERVAL_MS));
> +
>  	return 0;
> 
>  release_pre_req_mempool:
> @@ -2154,6 +2214,7 @@ static void ufshpb_discard_rsp_lists(struct
> ufshpb_lu *hpb)
>  static void ufshpb_cancel_jobs(struct ufshpb_lu *hpb)
>  {
>  	if (hpb->is_hcm) {
> +		cancel_delayed_work_sync(&hpb->ufshpb_read_to_work);
>  		cancel_work_sync(&hpb->ufshpb_lun_reset_work);
>  		cancel_work_sync(&hpb->ufshpb_normalization_work);
>  	}
> @@ -2264,6 +2325,10 @@ void ufshpb_resume(struct ufs_hba *hba)
>  			continue;
>  		ufshpb_set_state(hpb, HPB_PRESENT);
>  		ufshpb_kick_map_work(hpb);
> +		if (hpb->is_hcm)
> +			schedule_delayed_work(&hpb->ufshpb_read_to_work,
> +				msecs_to_jiffies(POLLING_INTERVAL_MS));
> +
>  	}
>  }
> 
> diff --git a/drivers/scsi/ufs/ufshpb.h b/drivers/scsi/ufs/ufshpb.h
> index 37c1b0ea0c0a..b49e9a34267f 100644
> --- a/drivers/scsi/ufs/ufshpb.h
> +++ b/drivers/scsi/ufs/ufshpb.h
> @@ -109,6 +109,7 @@ struct ufshpb_subregion {
>  };
> 
>  struct ufshpb_region {
> +	struct ufshpb_lu *hpb;
>  	struct ufshpb_subregion *srgn_tbl;
>  	enum HPB_RGN_STATE rgn_state;
>  	int rgn_idx;
> @@ -126,6 +127,10 @@ struct ufshpb_region {
>  	/* region reads - for host mode */
>  	spinlock_t rgn_lock;
>  	unsigned int reads;
> +	/* region "cold" timer - for host mode */
> +	ktime_t read_timeout;
> +	unsigned int read_timeout_expiries;
> +	struct list_head list_expired_rgn;
>  };
> 
>  #define for_each_sub_region(rgn, i, srgn)				\
> @@ -219,6 +224,7 @@ struct ufshpb_lu {
>  	struct victim_select_info lru_info;
>  	struct work_struct ufshpb_normalization_work;
>  	struct work_struct ufshpb_lun_reset_work;
> +	struct delayed_work ufshpb_read_to_work;
> 
>  	/* pinned region information */
>  	u32 lu_pinned_start;
Avri Altman March 16, 2021, 9:21 a.m. UTC | #4
> > +static void ufshpb_read_to_handler(struct work_struct *work)
> > +{
> > +     struct delayed_work *dwork = to_delayed_work(work);
> > +     struct ufshpb_lu *hpb;
> > +     struct victim_select_info *lru_info;
> > +     struct ufshpb_region *rgn;
> > +     unsigned long flags;
> > +     LIST_HEAD(expired_list);
> > +
> > +     hpb = container_of(dwork, struct ufshpb_lu, ufshpb_read_to_work);
> > +
> > +     spin_lock_irqsave(&hpb->rgn_state_lock, flags);
> > +
> > +     lru_info = &hpb->lru_info;
> > +
> > +     list_for_each_entry(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);
> > +                     else
> > +                             rgn->read_timeout = ktime_add_ms(ktime_get(),
> > +                                                      READ_TO_MS);
> > +             }
> > +     }
> > +
> > +     spin_unlock_irqrestore(&hpb->rgn_state_lock, flags);
> > +
> > +     list_for_each_entry(rgn, &expired_list, list_expired_rgn) {
> 
> Here can be problematic - since you don't have the native expired_list
> initialized
> before use, if above loop did not insert anything to expired_list, it
> shall become
> a dead loop here.
Not sure what you meant by native initialization.
LIST_HEAD is statically initializing an empty list, resulting the same outcome as INIT_LIST_HEAD.

> 
> And, which lock is protecting rgn->list_expired_rgn? If two
> read_to_handler works
> are running in parallel, one can be inserting it to its expired_list
> while another
> can be deleting it.
The timeout handler, being a delayed work, is meant to run every polling period.
Originally, I had it protected from 2 handlers running concurrently,
But I removed it following Daejun's comment, which I accepted,
Since it is always scheduled using the same polling period.

Thanks,
Avri

> 
> Can Guo.
> 
> > +             list_del_init(&rgn->list_expired_rgn);
> > +             spin_lock_irqsave(&hpb->rsp_list_lock, flags);
> > +             ufshpb_update_inactive_info(hpb, rgn->rgn_idx);
> > +             hpb->stats.rb_inactive_cnt++;
> > +             spin_unlock_irqrestore(&hpb->rsp_list_lock, flags);
> > +     }
> > +
> > +     ufshpb_kick_map_work(hpb);
> > +
> > +     schedule_delayed_work(&hpb->ufshpb_read_to_work,
> > +                           msecs_to_jiffies(POLLING_INTERVAL_MS));
> > +}
> > +
> >  static void ufshpb_add_lru_info(struct victim_select_info *lru_info,
> >                               struct ufshpb_region *rgn)
> >  {
> >       rgn->rgn_state = HPB_RGN_ACTIVE;
> >       list_add_tail(&rgn->list_lru_rgn, &lru_info->lh_lru_rgn);
> >       atomic_inc(&lru_info->active_cnt);
> > +     if (rgn->hpb->is_hcm) {
> > +             rgn->read_timeout = ktime_add_ms(ktime_get(), READ_TO_MS);
> > +             rgn->read_timeout_expiries = READ_TO_EXPIRIES;
> > +     }
> >  }
> >
> >  static void ufshpb_hit_lru_info(struct victim_select_info *lru_info,
> > @@ -1813,6 +1865,7 @@ static int ufshpb_alloc_region_tbl(struct
> > ufs_hba *hba, struct ufshpb_lu *hpb)
> >
> >               INIT_LIST_HEAD(&rgn->list_inact_rgn);
> >               INIT_LIST_HEAD(&rgn->list_lru_rgn);
> > +             INIT_LIST_HEAD(&rgn->list_expired_rgn);
> >
> >               if (rgn_idx == hpb->rgns_per_lu - 1) {
> >                       srgn_cnt = ((hpb->srgns_per_lu - 1) %
> > @@ -1834,6 +1887,7 @@ static int ufshpb_alloc_region_tbl(struct
> > ufs_hba *hba, struct ufshpb_lu *hpb)
> >               }
> >
> >               rgn->rgn_flags = 0;
> > +             rgn->hpb = hpb;
> >       }
> >
> >       return 0;
> > @@ -2053,6 +2107,8 @@ static int ufshpb_lu_hpb_init(struct ufs_hba
> > *hba, struct ufshpb_lu *hpb)
> >                         ufshpb_normalization_work_handler);
> >               INIT_WORK(&hpb->ufshpb_lun_reset_work,
> >                         ufshpb_reset_work_handler);
> > +             INIT_DELAYED_WORK(&hpb->ufshpb_read_to_work,
> > +                               ufshpb_read_to_handler);
> >       }
> >
> >       hpb->map_req_cache = kmem_cache_create("ufshpb_req_cache",
> > @@ -2087,6 +2143,10 @@ static int ufshpb_lu_hpb_init(struct ufs_hba
> > *hba, struct ufshpb_lu *hpb)
> >       ufshpb_stat_init(hpb);
> >       ufshpb_param_init(hpb);
> >
> > +     if (hpb->is_hcm)
> > +             schedule_delayed_work(&hpb->ufshpb_read_to_work,
> > +                                   msecs_to_jiffies(POLLING_INTERVAL_MS));
> > +
> >       return 0;
> >
> >  release_pre_req_mempool:
> > @@ -2154,6 +2214,7 @@ static void ufshpb_discard_rsp_lists(struct
> > ufshpb_lu *hpb)
> >  static void ufshpb_cancel_jobs(struct ufshpb_lu *hpb)
> >  {
> >       if (hpb->is_hcm) {
> > +             cancel_delayed_work_sync(&hpb->ufshpb_read_to_work);
> >               cancel_work_sync(&hpb->ufshpb_lun_reset_work);
> >               cancel_work_sync(&hpb->ufshpb_normalization_work);
> >       }
> > @@ -2264,6 +2325,10 @@ void ufshpb_resume(struct ufs_hba *hba)
> >                       continue;
> >               ufshpb_set_state(hpb, HPB_PRESENT);
> >               ufshpb_kick_map_work(hpb);
> > +             if (hpb->is_hcm)
> > +                     schedule_delayed_work(&hpb->ufshpb_read_to_work,
> > +                             msecs_to_jiffies(POLLING_INTERVAL_MS));
> > +
> >       }
> >  }
> >
> > diff --git a/drivers/scsi/ufs/ufshpb.h b/drivers/scsi/ufs/ufshpb.h
> > index 37c1b0ea0c0a..b49e9a34267f 100644
> > --- a/drivers/scsi/ufs/ufshpb.h
> > +++ b/drivers/scsi/ufs/ufshpb.h
> > @@ -109,6 +109,7 @@ struct ufshpb_subregion {
> >  };
> >
> >  struct ufshpb_region {
> > +     struct ufshpb_lu *hpb;
> >       struct ufshpb_subregion *srgn_tbl;
> >       enum HPB_RGN_STATE rgn_state;
> >       int rgn_idx;
> > @@ -126,6 +127,10 @@ struct ufshpb_region {
> >       /* region reads - for host mode */
> >       spinlock_t rgn_lock;
> >       unsigned int reads;
> > +     /* region "cold" timer - for host mode */
> > +     ktime_t read_timeout;
> > +     unsigned int read_timeout_expiries;
> > +     struct list_head list_expired_rgn;
> >  };
> >
> >  #define for_each_sub_region(rgn, i, srgn)                            \
> > @@ -219,6 +224,7 @@ struct ufshpb_lu {
> >       struct victim_select_info lru_info;
> >       struct work_struct ufshpb_normalization_work;
> >       struct work_struct ufshpb_lun_reset_work;
> > +     struct delayed_work ufshpb_read_to_work;
> >
> >       /* pinned region information */
> >       u32 lu_pinned_start;
Can Guo March 17, 2021, 2:45 a.m. UTC | #5
On 2021-03-16 17:21, Avri Altman wrote:
>> > +static void ufshpb_read_to_handler(struct work_struct *work)
>> > +{
>> > +     struct delayed_work *dwork = to_delayed_work(work);
>> > +     struct ufshpb_lu *hpb;
>> > +     struct victim_select_info *lru_info;
>> > +     struct ufshpb_region *rgn;
>> > +     unsigned long flags;
>> > +     LIST_HEAD(expired_list);
>> > +
>> > +     hpb = container_of(dwork, struct ufshpb_lu, ufshpb_read_to_work);
>> > +
>> > +     spin_lock_irqsave(&hpb->rgn_state_lock, flags);
>> > +
>> > +     lru_info = &hpb->lru_info;
>> > +
>> > +     list_for_each_entry(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);
>> > +                     else
>> > +                             rgn->read_timeout = ktime_add_ms(ktime_get(),
>> > +                                                      READ_TO_MS);
>> > +             }
>> > +     }
>> > +
>> > +     spin_unlock_irqrestore(&hpb->rgn_state_lock, flags);
>> > +
>> > +     list_for_each_entry(rgn, &expired_list, list_expired_rgn) {
>> 
>> Here can be problematic - since you don't have the native expired_list
>> initialized
>> before use, if above loop did not insert anything to expired_list, it
>> shall become
>> a dead loop here.
> Not sure what you meant by native initialization.
> LIST_HEAD is statically initializing an empty list, resulting the same
> outcome as INIT_LIST_HEAD.
> 

Sorry for making you confused, you should use list_for_each_entry_safe()
instead of list_for_each_entry() as you are deleting entries within the 
loop,
otherwise, this can become an infinite loop. Again, have you tested this 
patch
before upload? I am sure this is problematic - when it becomes an 
inifinite
loop, below path will hang...

ufshcd_suspend()->ufshpb_suspend()->cancel_jobs()->cancel_delayed_work()

>> 
>> And, which lock is protecting rgn->list_expired_rgn? If two
>> read_to_handler works
>> are running in parallel, one can be inserting it to its expired_list
>> while another
>> can be deleting it.
> The timeout handler, being a delayed work, is meant to run every 
> polling period.
> Originally, I had it protected from 2 handlers running concurrently,
> But I removed it following Daejun's comment, which I accepted,
> Since it is always scheduled using the same polling period.

But one can set the delay to 0 through sysfs, right?

Thanks,
Can Guo.

> 
> Thanks,
> Avri
> 
>> 
>> Can Guo.
>> 
>> > +             list_del_init(&rgn->list_expired_rgn);
>> > +             spin_lock_irqsave(&hpb->rsp_list_lock, flags);
>> > +             ufshpb_update_inactive_info(hpb, rgn->rgn_idx);
>> > +             hpb->stats.rb_inactive_cnt++;
>> > +             spin_unlock_irqrestore(&hpb->rsp_list_lock, flags);
>> > +     }
>> > +
>> > +     ufshpb_kick_map_work(hpb);
>> > +
>> > +     schedule_delayed_work(&hpb->ufshpb_read_to_work,
>> > +                           msecs_to_jiffies(POLLING_INTERVAL_MS));
>> > +}
>> > +
>> >  static void ufshpb_add_lru_info(struct victim_select_info *lru_info,
>> >                               struct ufshpb_region *rgn)
>> >  {
>> >       rgn->rgn_state = HPB_RGN_ACTIVE;
>> >       list_add_tail(&rgn->list_lru_rgn, &lru_info->lh_lru_rgn);
>> >       atomic_inc(&lru_info->active_cnt);
>> > +     if (rgn->hpb->is_hcm) {
>> > +             rgn->read_timeout = ktime_add_ms(ktime_get(), READ_TO_MS);
>> > +             rgn->read_timeout_expiries = READ_TO_EXPIRIES;
>> > +     }
>> >  }
>> >
>> >  static void ufshpb_hit_lru_info(struct victim_select_info *lru_info,
>> > @@ -1813,6 +1865,7 @@ static int ufshpb_alloc_region_tbl(struct
>> > ufs_hba *hba, struct ufshpb_lu *hpb)
>> >
>> >               INIT_LIST_HEAD(&rgn->list_inact_rgn);
>> >               INIT_LIST_HEAD(&rgn->list_lru_rgn);
>> > +             INIT_LIST_HEAD(&rgn->list_expired_rgn);
>> >
>> >               if (rgn_idx == hpb->rgns_per_lu - 1) {
>> >                       srgn_cnt = ((hpb->srgns_per_lu - 1) %
>> > @@ -1834,6 +1887,7 @@ static int ufshpb_alloc_region_tbl(struct
>> > ufs_hba *hba, struct ufshpb_lu *hpb)
>> >               }
>> >
>> >               rgn->rgn_flags = 0;
>> > +             rgn->hpb = hpb;
>> >       }
>> >
>> >       return 0;
>> > @@ -2053,6 +2107,8 @@ static int ufshpb_lu_hpb_init(struct ufs_hba
>> > *hba, struct ufshpb_lu *hpb)
>> >                         ufshpb_normalization_work_handler);
>> >               INIT_WORK(&hpb->ufshpb_lun_reset_work,
>> >                         ufshpb_reset_work_handler);
>> > +             INIT_DELAYED_WORK(&hpb->ufshpb_read_to_work,
>> > +                               ufshpb_read_to_handler);
>> >       }
>> >
>> >       hpb->map_req_cache = kmem_cache_create("ufshpb_req_cache",
>> > @@ -2087,6 +2143,10 @@ static int ufshpb_lu_hpb_init(struct ufs_hba
>> > *hba, struct ufshpb_lu *hpb)
>> >       ufshpb_stat_init(hpb);
>> >       ufshpb_param_init(hpb);
>> >
>> > +     if (hpb->is_hcm)
>> > +             schedule_delayed_work(&hpb->ufshpb_read_to_work,
>> > +                                   msecs_to_jiffies(POLLING_INTERVAL_MS));
>> > +
>> >       return 0;
>> >
>> >  release_pre_req_mempool:
>> > @@ -2154,6 +2214,7 @@ static void ufshpb_discard_rsp_lists(struct
>> > ufshpb_lu *hpb)
>> >  static void ufshpb_cancel_jobs(struct ufshpb_lu *hpb)
>> >  {
>> >       if (hpb->is_hcm) {
>> > +             cancel_delayed_work_sync(&hpb->ufshpb_read_to_work);
>> >               cancel_work_sync(&hpb->ufshpb_lun_reset_work);
>> >               cancel_work_sync(&hpb->ufshpb_normalization_work);
>> >       }
>> > @@ -2264,6 +2325,10 @@ void ufshpb_resume(struct ufs_hba *hba)
>> >                       continue;
>> >               ufshpb_set_state(hpb, HPB_PRESENT);
>> >               ufshpb_kick_map_work(hpb);
>> > +             if (hpb->is_hcm)
>> > +                     schedule_delayed_work(&hpb->ufshpb_read_to_work,
>> > +                             msecs_to_jiffies(POLLING_INTERVAL_MS));
>> > +
>> >       }
>> >  }
>> >
>> > diff --git a/drivers/scsi/ufs/ufshpb.h b/drivers/scsi/ufs/ufshpb.h
>> > index 37c1b0ea0c0a..b49e9a34267f 100644
>> > --- a/drivers/scsi/ufs/ufshpb.h
>> > +++ b/drivers/scsi/ufs/ufshpb.h
>> > @@ -109,6 +109,7 @@ struct ufshpb_subregion {
>> >  };
>> >
>> >  struct ufshpb_region {
>> > +     struct ufshpb_lu *hpb;
>> >       struct ufshpb_subregion *srgn_tbl;
>> >       enum HPB_RGN_STATE rgn_state;
>> >       int rgn_idx;
>> > @@ -126,6 +127,10 @@ struct ufshpb_region {
>> >       /* region reads - for host mode */
>> >       spinlock_t rgn_lock;
>> >       unsigned int reads;
>> > +     /* region "cold" timer - for host mode */
>> > +     ktime_t read_timeout;
>> > +     unsigned int read_timeout_expiries;
>> > +     struct list_head list_expired_rgn;
>> >  };
>> >
>> >  #define for_each_sub_region(rgn, i, srgn)                            \
>> > @@ -219,6 +224,7 @@ struct ufshpb_lu {
>> >       struct victim_select_info lru_info;
>> >       struct work_struct ufshpb_normalization_work;
>> >       struct work_struct ufshpb_lun_reset_work;
>> > +     struct delayed_work ufshpb_read_to_work;
>> >
>> >       /* pinned region information */
>> >       u32 lu_pinned_start;
Avri Altman March 17, 2021, 7:55 a.m. UTC | #6
> On 2021-03-16 17:21, Avri Altman wrote:
> >> > +static void ufshpb_read_to_handler(struct work_struct *work)
> >> > +{
> >> > +     struct delayed_work *dwork = to_delayed_work(work);
> >> > +     struct ufshpb_lu *hpb;
> >> > +     struct victim_select_info *lru_info;
> >> > +     struct ufshpb_region *rgn;
> >> > +     unsigned long flags;
> >> > +     LIST_HEAD(expired_list);
> >> > +
> >> > +     hpb = container_of(dwork, struct ufshpb_lu, ufshpb_read_to_work);
> >> > +
> >> > +     spin_lock_irqsave(&hpb->rgn_state_lock, flags);
> >> > +
> >> > +     lru_info = &hpb->lru_info;
> >> > +
> >> > +     list_for_each_entry(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);
> >> > +                     else
> >> > +                             rgn->read_timeout = ktime_add_ms(ktime_get(),
> >> > +                                                      READ_TO_MS);
> >> > +             }
> >> > +     }
> >> > +
> >> > +     spin_unlock_irqrestore(&hpb->rgn_state_lock, flags);
> >> > +
> >> > +     list_for_each_entry(rgn, &expired_list, list_expired_rgn) {
> >>
> >> Here can be problematic - since you don't have the native expired_list
> >> initialized
> >> before use, if above loop did not insert anything to expired_list, it
> >> shall become
> >> a dead loop here.
> > Not sure what you meant by native initialization.
> > LIST_HEAD is statically initializing an empty list, resulting the same
> > outcome as INIT_LIST_HEAD.
> >
> 
> Sorry for making you confused, you should use list_for_each_entry_safe()
> instead of list_for_each_entry() as you are deleting entries within the
> loop,
> otherwise, this can become an infinite loop. Again, have you tested this
> patch
> before upload? I am sure this is problematic - when it becomes an
> inifinite
> loop, below path will hang...
> 
> ufshcd_suspend()->ufshpb_suspend()->cancel_jobs()->cancel_delayed_work()
Ahh  - yes.  You are right.  Originally I used list_for_each_entry_safe.
Not sure why I changed it here.  Will fix it.

I openly disclosed that I am testing the code on gs20 and mi10.
Those are v4.19 platforms, and I am using a driver adopted from the original public hpb driver
Published by Samsung with the gs20 code.
I am also concern as those drivers are drifted apart as the review process commences.
Will try to bring-up a more advanced platform (gs21) and apply the mainline hpb driver.


> 
> >>
> >> And, which lock is protecting rgn->list_expired_rgn? If two
> >> read_to_handler works
> >> are running in parallel, one can be inserting it to its expired_list
> >> while another
> >> can be deleting it.
> > The timeout handler, being a delayed work, is meant to run every
> > polling period.
> > Originally, I had it protected from 2 handlers running concurrently,
> > But I removed it following Daejun's comment, which I accepted,
> > Since it is always scheduled using the same polling period.
> 
> But one can set the delay to 0 through sysfs, right?
Will restore the protection.  Thanks.

Thanks,
Avri

> 
> Thanks,
> Can Guo.
> 
> >
> > Thanks,
> > Avri
> >
> >>
> >> Can Guo.
> >>
> >> > +             list_del_init(&rgn->list_expired_rgn);
> >> > +             spin_lock_irqsave(&hpb->rsp_list_lock, flags);
> >> > +             ufshpb_update_inactive_info(hpb, rgn->rgn_idx);
> >> > +             hpb->stats.rb_inactive_cnt++;
> >> > +             spin_unlock_irqrestore(&hpb->rsp_list_lock, flags);
> >> > +     }
> >> > +
> >> > +     ufshpb_kick_map_work(hpb);
> >> > +
> >> > +     schedule_delayed_work(&hpb->ufshpb_read_to_work,
> >> > +                           msecs_to_jiffies(POLLING_INTERVAL_MS));
> >> > +}
> >> > +
> >> >  static void ufshpb_add_lru_info(struct victim_select_info *lru_info,
> >> >                               struct ufshpb_region *rgn)
> >> >  {
> >> >       rgn->rgn_state = HPB_RGN_ACTIVE;
> >> >       list_add_tail(&rgn->list_lru_rgn, &lru_info->lh_lru_rgn);
> >> >       atomic_inc(&lru_info->active_cnt);
> >> > +     if (rgn->hpb->is_hcm) {
> >> > +             rgn->read_timeout = ktime_add_ms(ktime_get(), READ_TO_MS);
> >> > +             rgn->read_timeout_expiries = READ_TO_EXPIRIES;
> >> > +     }
> >> >  }
> >> >
> >> >  static void ufshpb_hit_lru_info(struct victim_select_info *lru_info,
> >> > @@ -1813,6 +1865,7 @@ static int ufshpb_alloc_region_tbl(struct
> >> > ufs_hba *hba, struct ufshpb_lu *hpb)
> >> >
> >> >               INIT_LIST_HEAD(&rgn->list_inact_rgn);
> >> >               INIT_LIST_HEAD(&rgn->list_lru_rgn);
> >> > +             INIT_LIST_HEAD(&rgn->list_expired_rgn);
> >> >
> >> >               if (rgn_idx == hpb->rgns_per_lu - 1) {
> >> >                       srgn_cnt = ((hpb->srgns_per_lu - 1) %
> >> > @@ -1834,6 +1887,7 @@ static int ufshpb_alloc_region_tbl(struct
> >> > ufs_hba *hba, struct ufshpb_lu *hpb)
> >> >               }
> >> >
> >> >               rgn->rgn_flags = 0;
> >> > +             rgn->hpb = hpb;
> >> >       }
> >> >
> >> >       return 0;
> >> > @@ -2053,6 +2107,8 @@ static int ufshpb_lu_hpb_init(struct ufs_hba
> >> > *hba, struct ufshpb_lu *hpb)
> >> >                         ufshpb_normalization_work_handler);
> >> >               INIT_WORK(&hpb->ufshpb_lun_reset_work,
> >> >                         ufshpb_reset_work_handler);
> >> > +             INIT_DELAYED_WORK(&hpb->ufshpb_read_to_work,
> >> > +                               ufshpb_read_to_handler);
> >> >       }
> >> >
> >> >       hpb->map_req_cache = kmem_cache_create("ufshpb_req_cache",
> >> > @@ -2087,6 +2143,10 @@ static int ufshpb_lu_hpb_init(struct ufs_hba
> >> > *hba, struct ufshpb_lu *hpb)
> >> >       ufshpb_stat_init(hpb);
> >> >       ufshpb_param_init(hpb);
> >> >
> >> > +     if (hpb->is_hcm)
> >> > +             schedule_delayed_work(&hpb->ufshpb_read_to_work,
> >> > +                                   msecs_to_jiffies(POLLING_INTERVAL_MS));
> >> > +
> >> >       return 0;
> >> >
> >> >  release_pre_req_mempool:
> >> > @@ -2154,6 +2214,7 @@ static void ufshpb_discard_rsp_lists(struct
> >> > ufshpb_lu *hpb)
> >> >  static void ufshpb_cancel_jobs(struct ufshpb_lu *hpb)
> >> >  {
> >> >       if (hpb->is_hcm) {
> >> > +             cancel_delayed_work_sync(&hpb->ufshpb_read_to_work);
> >> >               cancel_work_sync(&hpb->ufshpb_lun_reset_work);
> >> >               cancel_work_sync(&hpb->ufshpb_normalization_work);
> >> >       }
> >> > @@ -2264,6 +2325,10 @@ void ufshpb_resume(struct ufs_hba *hba)
> >> >                       continue;
> >> >               ufshpb_set_state(hpb, HPB_PRESENT);
> >> >               ufshpb_kick_map_work(hpb);
> >> > +             if (hpb->is_hcm)
> >> > +                     schedule_delayed_work(&hpb->ufshpb_read_to_work,
> >> > +                             msecs_to_jiffies(POLLING_INTERVAL_MS));
> >> > +
> >> >       }
> >> >  }
> >> >
> >> > diff --git a/drivers/scsi/ufs/ufshpb.h b/drivers/scsi/ufs/ufshpb.h
> >> > index 37c1b0ea0c0a..b49e9a34267f 100644
> >> > --- a/drivers/scsi/ufs/ufshpb.h
> >> > +++ b/drivers/scsi/ufs/ufshpb.h
> >> > @@ -109,6 +109,7 @@ struct ufshpb_subregion {
> >> >  };
> >> >
> >> >  struct ufshpb_region {
> >> > +     struct ufshpb_lu *hpb;
> >> >       struct ufshpb_subregion *srgn_tbl;
> >> >       enum HPB_RGN_STATE rgn_state;
> >> >       int rgn_idx;
> >> > @@ -126,6 +127,10 @@ struct ufshpb_region {
> >> >       /* region reads - for host mode */
> >> >       spinlock_t rgn_lock;
> >> >       unsigned int reads;
> >> > +     /* region "cold" timer - for host mode */
> >> > +     ktime_t read_timeout;
> >> > +     unsigned int read_timeout_expiries;
> >> > +     struct list_head list_expired_rgn;
> >> >  };
> >> >
> >> >  #define for_each_sub_region(rgn, i, srgn)                            \
> >> > @@ -219,6 +224,7 @@ struct ufshpb_lu {
> >> >       struct victim_select_info lru_info;
> >> >       struct work_struct ufshpb_normalization_work;
> >> >       struct work_struct ufshpb_lun_reset_work;
> >> > +     struct delayed_work ufshpb_read_to_work;
> >> >
> >> >       /* pinned region information */
> >> >       u32 lu_pinned_start;

Patch
diff mbox series

diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
index 0034fa03fdc6..89a930e72cff 100644
--- a/drivers/scsi/ufs/ufshpb.c
+++ b/drivers/scsi/ufs/ufshpb.c
@@ -18,6 +18,9 @@ 
 
 #define ACTIVATION_THRESHOLD 4 /* 4 IOs */
 #define EVICTION_THRESHOLD (ACTIVATION_THRESHOLD << 6) /* 256 IOs */
+#define READ_TO_MS 1000
+#define READ_TO_EXPIRIES 100
+#define POLLING_INTERVAL_MS 200
 
 /* memory management */
 static struct kmem_cache *ufshpb_mctx_cache;
@@ -1024,12 +1027,61 @@  static int ufshpb_check_srgns_issue_state(struct ufshpb_lu *hpb,
 	return 0;
 }
 
+static void ufshpb_read_to_handler(struct work_struct *work)
+{
+	struct delayed_work *dwork = to_delayed_work(work);
+	struct ufshpb_lu *hpb;
+	struct victim_select_info *lru_info;
+	struct ufshpb_region *rgn;
+	unsigned long flags;
+	LIST_HEAD(expired_list);
+
+	hpb = container_of(dwork, struct ufshpb_lu, ufshpb_read_to_work);
+
+	spin_lock_irqsave(&hpb->rgn_state_lock, flags);
+
+	lru_info = &hpb->lru_info;
+
+	list_for_each_entry(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);
+			else
+				rgn->read_timeout = ktime_add_ms(ktime_get(),
+							 READ_TO_MS);
+		}
+	}
+
+	spin_unlock_irqrestore(&hpb->rgn_state_lock, flags);
+
+	list_for_each_entry(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);
+		hpb->stats.rb_inactive_cnt++;
+		spin_unlock_irqrestore(&hpb->rsp_list_lock, flags);
+	}
+
+	ufshpb_kick_map_work(hpb);
+
+	schedule_delayed_work(&hpb->ufshpb_read_to_work,
+			      msecs_to_jiffies(POLLING_INTERVAL_MS));
+}
+
 static void ufshpb_add_lru_info(struct victim_select_info *lru_info,
 				struct ufshpb_region *rgn)
 {
 	rgn->rgn_state = HPB_RGN_ACTIVE;
 	list_add_tail(&rgn->list_lru_rgn, &lru_info->lh_lru_rgn);
 	atomic_inc(&lru_info->active_cnt);
+	if (rgn->hpb->is_hcm) {
+		rgn->read_timeout = ktime_add_ms(ktime_get(), READ_TO_MS);
+		rgn->read_timeout_expiries = READ_TO_EXPIRIES;
+	}
 }
 
 static void ufshpb_hit_lru_info(struct victim_select_info *lru_info,
@@ -1813,6 +1865,7 @@  static int ufshpb_alloc_region_tbl(struct ufs_hba *hba, struct ufshpb_lu *hpb)
 
 		INIT_LIST_HEAD(&rgn->list_inact_rgn);
 		INIT_LIST_HEAD(&rgn->list_lru_rgn);
+		INIT_LIST_HEAD(&rgn->list_expired_rgn);
 
 		if (rgn_idx == hpb->rgns_per_lu - 1) {
 			srgn_cnt = ((hpb->srgns_per_lu - 1) %
@@ -1834,6 +1887,7 @@  static int ufshpb_alloc_region_tbl(struct ufs_hba *hba, struct ufshpb_lu *hpb)
 		}
 
 		rgn->rgn_flags = 0;
+		rgn->hpb = hpb;
 	}
 
 	return 0;
@@ -2053,6 +2107,8 @@  static int ufshpb_lu_hpb_init(struct ufs_hba *hba, struct ufshpb_lu *hpb)
 			  ufshpb_normalization_work_handler);
 		INIT_WORK(&hpb->ufshpb_lun_reset_work,
 			  ufshpb_reset_work_handler);
+		INIT_DELAYED_WORK(&hpb->ufshpb_read_to_work,
+				  ufshpb_read_to_handler);
 	}
 
 	hpb->map_req_cache = kmem_cache_create("ufshpb_req_cache",
@@ -2087,6 +2143,10 @@  static int ufshpb_lu_hpb_init(struct ufs_hba *hba, struct ufshpb_lu *hpb)
 	ufshpb_stat_init(hpb);
 	ufshpb_param_init(hpb);
 
+	if (hpb->is_hcm)
+		schedule_delayed_work(&hpb->ufshpb_read_to_work,
+				      msecs_to_jiffies(POLLING_INTERVAL_MS));
+
 	return 0;
 
 release_pre_req_mempool:
@@ -2154,6 +2214,7 @@  static void ufshpb_discard_rsp_lists(struct ufshpb_lu *hpb)
 static void ufshpb_cancel_jobs(struct ufshpb_lu *hpb)
 {
 	if (hpb->is_hcm) {
+		cancel_delayed_work_sync(&hpb->ufshpb_read_to_work);
 		cancel_work_sync(&hpb->ufshpb_lun_reset_work);
 		cancel_work_sync(&hpb->ufshpb_normalization_work);
 	}
@@ -2264,6 +2325,10 @@  void ufshpb_resume(struct ufs_hba *hba)
 			continue;
 		ufshpb_set_state(hpb, HPB_PRESENT);
 		ufshpb_kick_map_work(hpb);
+		if (hpb->is_hcm)
+			schedule_delayed_work(&hpb->ufshpb_read_to_work,
+				msecs_to_jiffies(POLLING_INTERVAL_MS));
+
 	}
 }
 
diff --git a/drivers/scsi/ufs/ufshpb.h b/drivers/scsi/ufs/ufshpb.h
index 37c1b0ea0c0a..b49e9a34267f 100644
--- a/drivers/scsi/ufs/ufshpb.h
+++ b/drivers/scsi/ufs/ufshpb.h
@@ -109,6 +109,7 @@  struct ufshpb_subregion {
 };
 
 struct ufshpb_region {
+	struct ufshpb_lu *hpb;
 	struct ufshpb_subregion *srgn_tbl;
 	enum HPB_RGN_STATE rgn_state;
 	int rgn_idx;
@@ -126,6 +127,10 @@  struct ufshpb_region {
 	/* region reads - for host mode */
 	spinlock_t rgn_lock;
 	unsigned int reads;
+	/* region "cold" timer - for host mode */
+	ktime_t read_timeout;
+	unsigned int read_timeout_expiries;
+	struct list_head list_expired_rgn;
 };
 
 #define for_each_sub_region(rgn, i, srgn)				\
@@ -219,6 +224,7 @@  struct ufshpb_lu {
 	struct victim_select_info lru_info;
 	struct work_struct ufshpb_normalization_work;
 	struct work_struct ufshpb_lun_reset_work;
+	struct delayed_work ufshpb_read_to_work;
 
 	/* pinned region information */
 	u32 lu_pinned_start;