Re: [PATCH v5 08/10] scsi: ufshpb: Limit the number of inflight map requests

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On 2021-03-02 21:25, Avri Altman wrote:
in host control mode the host is the originator of map requests. To not

in -> In

Thanks,
Can Guo.

flood the device with map requests, use a simple throttling mechanism
that limits the number of inflight map requests.

Signed-off-by: Avri Altman <avri.altman@xxxxxxx>
---
 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 89a930e72cff..74da69727340 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;
@@ -750,6 +751,14 @@ 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_SCSI_IN);
 	if (!map_req)
 		return NULL;
@@ -764,6 +773,7 @@ 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;
 }
@@ -773,6 +783,7 @@ 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 b49e9a34267f..d83ab488688a 100644
--- a/drivers/scsi/ufs/ufshpb.h
+++ b/drivers/scsi/ufs/ufshpb.h
@@ -212,6 +212,7 @@ 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;



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