From: Avri Altman <avri.altman@wdc.com>
Date: Mon, 12 Jul 2021 12:50:36 +0300
Subject: [PATCH] scsi: ufs: ufshpb: Limit the number of in-flight map requests
Git-commit: 33845a2d844be6157914cf81b7170e4b12a5bf17
Patch-mainline: v5.15-rc1
References: jsc#PED-818

In host control mode the host is the originator of map requests. To not
flood the device with map requests, use a simple throttling mechanism that
limits the number of in-flight map requests.

Link: https://lore.kernel.org/r/20210712095039.8093-10-avri.altman@wdc.com
Reviewed-by: Daejun Park <daejun7.park@samsung.com>
Signed-off-by: Avri Altman <avri.altman@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Hannes Reinecke <hare@suse.com>
---
 drivers/scsi/ufs/ufshpb.c | 11 +++++++++++
 drivers/scsi/ufs/ufshpb.h |  1 +
 2 files changed, 12 insertions(+)

diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
index 2d8c7bc12713..2a463b755808 100644
--- a/drivers/scsi/ufs/ufshpb.c
+++ b/drivers/scsi/ufs/ufshpb.c
@@ -21,6 +21,7 @@
 #define READ_TO_MS 1000
 #define READ_TO_EXPIRIES 100
 #define POLLING_INTERVAL_MS 200
+#define THROTTLE_MAP_REQ_DEFAULT 1
 
 /* memory management */
 static struct kmem_cache *ufshpb_mctx_cache;
@@ -742,6 +743,14 @@ static struct ufshpb_req *ufshpb_get_map_req(struct ufshpb_lu *hpb,
 	struct ufshpb_req *map_req;
 	struct bio *bio;
 
+	if (hpb->is_hcm &&
+	    hpb->num_inflight_map_req >= THROTTLE_MAP_REQ_DEFAULT) {
+		dev_info(&hpb->sdev_ufs_lu->sdev_dev,
+			 "map_req throttle. inflight %d throttle %d",
+			 hpb->num_inflight_map_req, THROTTLE_MAP_REQ_DEFAULT);
+		return NULL;
+	}
+
 	map_req = ufshpb_get_req(hpb, srgn->rgn_idx, REQ_OP_DRV_IN, false);
 	if (!map_req)
 		return NULL;
@@ -756,6 +765,7 @@ static struct ufshpb_req *ufshpb_get_map_req(struct ufshpb_lu *hpb,
 
 	map_req->rb.srgn_idx = srgn->srgn_idx;
 	map_req->rb.mctx = srgn->mctx;
+	hpb->num_inflight_map_req++;
 
 	return map_req;
 }
@@ -765,6 +775,7 @@ static void ufshpb_put_map_req(struct ufshpb_lu *hpb,
 {
 	bio_put(map_req->bio);
 	ufshpb_put_req(hpb, map_req);
+	hpb->num_inflight_map_req--;
 }
 
 static int ufshpb_clear_dirty_bitmap(struct ufshpb_lu *hpb,
diff --git a/drivers/scsi/ufs/ufshpb.h b/drivers/scsi/ufs/ufshpb.h
index 8309b59c7819..edf565e9036f 100644
--- a/drivers/scsi/ufs/ufshpb.h
+++ b/drivers/scsi/ufs/ufshpb.h
@@ -217,6 +217,7 @@ struct ufshpb_lu {
 	struct ufshpb_req *pre_req;
 	int num_inflight_pre_req;
 	int throttle_pre_req;
+	int num_inflight_map_req;
 	struct list_head lh_pre_req_free;
 	int cur_read_id;
 	int pre_req_min_tr_len;
-- 
2.35.3