linux-kernel - [PATCH v2 4/9] scsi: ufshpb: Make eviction depends on region's reads

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue,  2 Feb 2021 10:30:02 +0200
From:   Avri Altman <avri.altman@....com>
To:     "James E . J . Bottomley" <jejb@...ux.vnet.ibm.com>,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     gregkh@...uxfoundation.org, Bart Van Assche <bvanassche@....org>,
        yongmyung lee <ymhungry.lee@...sung.com>,
        Daejun Park <daejun7.park@...sung.com>,
        alim.akhtar@...sung.com, asutoshd@...eaurora.org,
        Zang Leigang <zangleigang@...ilicon.com>,
        Avi Shchislowski <avi.shchislowski@....com>,
        Bean Huo <beanhuo@...ron.com>, cang@...eaurora.org,
        stanley.chu@...iatek.com, Avri Altman <avri.altman@....com>
Subject: [PATCH v2 4/9] scsi: ufshpb: Make eviction depends on region's reads

In host mode, eviction is considered an extreme measure.
verify that the entering region has enough reads, and the exiting
region has much less reads.

Signed-off-by: Avri Altman <avri.altman@....com>
---
 drivers/scsi/ufs/ufshpb.c | 42 ++++++++++++++++++++++++++++++++++++---
 1 file changed, 39 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
index de4866d42df0..bae7dca105da 100644
--- a/drivers/scsi/ufs/ufshpb.c
+++ b/drivers/scsi/ufs/ufshpb.c
@@ -18,6 +18,7 @@
 
 #define WORK_PENDING 0
 #define ACTIVATION_THRSHLD 4 /* 4 IOs */
+#define EVICTION_THRSHLD (ACTIVATION_THRSHLD << 6) /* 256 IOs */
 
 /* memory management */
 static struct kmem_cache *ufshpb_mctx_cache;
@@ -644,6 +645,13 @@ static struct ufshpb_region *ufshpb_victim_lru_info(struct ufshpb_lu *hpb)
 		if (ufshpb_check_srgns_issue_state(hpb, rgn))
 			continue;
 
+		/*
+		 * in host control mode, verify that the exiting region
+		 * has less reads
+		 */
+		if (hpb->is_hcm && rgn->reads > (EVICTION_THRSHLD >> 1))
+			continue;
+
 		victim_rgn = rgn;
 		break;
 	}
@@ -799,7 +807,7 @@ static int ufshpb_issue_map_req(struct ufshpb_lu *hpb,
 
 static int ufshpb_add_region(struct ufshpb_lu *hpb, struct ufshpb_region *rgn)
 {
-	struct ufshpb_region *victim_rgn;
+	struct ufshpb_region *victim_rgn = NULL;
 	struct victim_select_info *lru_info = &hpb->lru_info;
 	unsigned long flags;
 	int ret = 0;
@@ -827,6 +835,16 @@ static int ufshpb_add_region(struct ufshpb_lu *hpb, struct ufshpb_region *rgn)
 			 * because the device could detect this region
 			 * by not issuing HPB_READ
 			 */
+
+			/*
+			 * in host control mode, verify that the entering
+			 * region has enough reads
+			 */
+			if (hpb->is_hcm && rgn->reads < EVICTION_THRSHLD) {
+				ret = -EACCES;
+				goto out;
+			}
+
 			victim_rgn = ufshpb_victim_lru_info(hpb);
 			if (!victim_rgn) {
 				dev_warn(&hpb->sdev_ufs_lu->sdev_dev,
@@ -1034,8 +1052,13 @@ static void ufshpb_run_active_subregion_list(struct ufshpb_lu *hpb)
 
 		rgn = hpb->rgn_tbl + srgn->rgn_idx;
 		ret = ufshpb_add_region(hpb, rgn);
-		if (ret)
-			goto active_failed;
+		if (ret) {
+			if (ret == -EACCES) {
+				spin_lock_irqsave(&hpb->rsp_list_lock, flags);
+				continue;
+			}
+			goto add_region_failed;
+		}
 
 		ret = ufshpb_issue_map_req(hpb, rgn, srgn);
 		if (ret) {
@@ -1049,9 +1072,22 @@ static void ufshpb_run_active_subregion_list(struct ufshpb_lu *hpb)
 	spin_unlock_irqrestore(&hpb->rsp_list_lock, flags);
 	return;
 
+add_region_failed:
+	if (hpb->is_hcm) {
+		/*
+		 * In host control mode, it is common that eviction trials
+		 * fail, either because the entering region didn't have enough
+		 * reads, or a poor-performing exiting region wasn't found.
+		 * No need to re-insert those regions to the "to-be-activated"
+		 * list.
+		 */
+		return;
+	}
+
 active_failed:
 	dev_err(&hpb->sdev_ufs_lu->sdev_dev, "failed to activate region %d - %d, will retry\n",
 		   rgn->rgn_idx, srgn->srgn_idx);
+
 	spin_lock_irqsave(&hpb->rsp_list_lock, flags);
 	ufshpb_add_active_list(hpb, rgn, srgn);
 	spin_unlock_irqrestore(&hpb->rsp_list_lock, flags);
-- 
2.25.1