[PATCH 7/8] scsi: ufshpb: Add "Cold" regions timer

[Avri Altman]

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 exahust its READ_TO_EXPIRIES - another parameter.

All this does not apply to pinned regions.

Signed-off-by: Avri Altman <avri.altman@xxxxxxx>
---
 drivers/scsi/ufs/ufshpb.c | 75 ++++++++++++++++++++++++++++++++++++++-
 drivers/scsi/ufs/ufshpb.h |  7 ++++
 2 files changed, 81 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
index cb99b57b4319..482f01c3b3ee 100644
--- a/drivers/scsi/ufs/ufshpb.c
+++ b/drivers/scsi/ufs/ufshpb.c
@@ -18,8 +18,12 @@
 
 #define WORK_PENDING 0
 #define RESET_PENDING 1
+#define TIMEOUT_WORK_PENDING 2
 #define ACTIVATION_THRSHLD 4 /* 4 IOs */
 #define EVICTION_THRSHLD (ACTIVATION_THRSHLD << 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;
@@ -671,12 +675,69 @@ 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, *next_rgn;
+	unsigned long flags;
+	LIST_HEAD(expired_list);
+
+	hpb = container_of(dwork, struct ufshpb_lu, ufshpb_read_to_work);
+
+	if (test_and_set_bit(TIMEOUT_WORK_PENDING, &hpb->work_data_bits))
+		return;
+
+	spin_lock_irqsave(&hpb->rgn_state_lock, flags);
+
+	lru_info = &hpb->lru_info;
+
+	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);
+		bool dirty, expired;
+
+		if (!timedout)
+			continue;
+
+		dirty = is_rgn_dirty(rgn);
+		expired = atomic_dec_and_test(&rgn->read_timeout_expiries);
+
+		if (dirty || expired)
+			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_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);
+		hpb->stats.rb_inactive_cnt++;
+		spin_unlock_irqrestore(&hpb->rsp_list_lock, flags);
+	}
+
+	clear_bit(TIMEOUT_WORK_PENDING, &hpb->work_data_bits);
+
+	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)
+				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 (ufshpb_mode == HPB_HOST_CONTROL) {
+		rgn->read_timeout = ktime_add_ms(ktime_get(), READ_TO_MS);
+		atomic_set(&rgn->read_timeout_expiries, READ_TO_EXPIRIES);
+	}
 }
 
 static void ufshpb_hit_lru_info(struct victim_select_info *lru_info,
@@ -1404,6 +1465,7 @@ 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) %
@@ -1536,6 +1598,8 @@ 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",
@@ -1562,6 +1626,10 @@ static int ufshpb_lu_hpb_init(struct ufs_hba *hba, struct ufshpb_lu *hpb)
 
 	ufshpb_stat_init(hpb);
 
+	if (ufshpb_mode == HPB_HOST_CONTROL)
+		schedule_delayed_work(&hpb->ufshpb_read_to_work,
+				      msecs_to_jiffies(POLLING_INTERVAL_MS));
+
 	return 0;
 
 release_m_page_cache:
@@ -1624,6 +1692,7 @@ static void ufshpb_discard_rsp_lists(struct ufshpb_lu *hpb)
 static void ufshpb_cancel_jobs(struct ufshpb_lu *hpb)
 {
 	if (ufshpb_mode == HPB_HOST_CONTROL) {
+		cancel_delayed_work_sync(&hpb->ufshpb_read_to_work);
 		cancel_work_sync(&hpb->ufshpb_lun_reset_work);
 		cancel_work_sync(&hpb->ufshpb_normalization_work);
 	}
@@ -1734,6 +1803,10 @@ void ufshpb_resume(struct ufs_hba *hba)
 			continue;
 		ufshpb_set_state(hpb, HPB_PRESENT);
 		ufshpb_kick_map_work(hpb);
+		if (ufshpb_mode == HPB_HOST_CONTROL)
+			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 4bf77169af00..86c16a4127bd 100644
--- a/drivers/scsi/ufs/ufshpb.h
+++ b/drivers/scsi/ufs/ufshpb.h
@@ -121,6 +121,12 @@ struct ufshpb_region {
 
 	/* region reads - for host mode */
 	atomic64_t reads;
+
+	/* region "cold" timer - for host mode */
+	ktime_t read_timeout;
+	atomic_t read_timeout_expiries;
+	struct list_head list_expired_rgn;
+
 };
 
 #define for_each_sub_region(rgn, i, srgn)				\
@@ -184,6 +190,7 @@ 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;
 	unsigned long work_data_bits;
 
 	/* pinned region information */
-- 
2.25.1