linux-kernel - [PATCH AUTOSEL for 4.9 275/281] mtd: mtd_oobtest: Handle bitflips during reads

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Date:   Mon, 19 Mar 2018 16:03:21 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
CC:     Miquel Raynal <miquel.raynal@...e-electrons.com>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL for 4.9 275/281] mtd: mtd_oobtest: Handle bitflips
 during reads

From: Miquel Raynal <miquel.raynal@...e-electrons.com>

[ Upstream commit 12663b442e5ac5aa3d6097cd3f287c71ba46d26e ]

Reads from NAND devices usually trigger bitflips, this is an expected
behavior. While bitflips are under a given threshold, the MTD core
returns 0. However, when the number of corrected bitflips is above this
same threshold, -EUCLEAN is returned to inform the upper layer that this
block is slightly dying and soon the ECC engine will be overtaken so
actions should be taken to move the data out of it.

This particular condition should not be treated like an error and the
test should continue.

Signed-off-by: Miquel Raynal <miquel.raynal@...e-electrons.com>
Signed-off-by: Boris Brezillon <boris.brezillon@...e-electrons.com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 drivers/mtd/tests/oobtest.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/mtd/tests/oobtest.c b/drivers/mtd/tests/oobtest.c
index 1cb3f7758fb6..766b2c385682 100644
--- a/drivers/mtd/tests/oobtest.c
+++ b/drivers/mtd/tests/oobtest.c
@@ -193,6 +193,9 @@ static int verify_eraseblock(int ebnum)
 		ops.datbuf    = NULL;
 		ops.oobbuf    = readbuf;
 		err = mtd_read_oob(mtd, addr, &ops);
+		if (mtd_is_bitflip(err))
+			err = 0;
+
 		if (err || ops.oobretlen != use_len) {
 			pr_err("error: readoob failed at %#llx\n",
 			       (long long)addr);
@@ -227,6 +230,9 @@ static int verify_eraseblock(int ebnum)
 			ops.datbuf    = NULL;
 			ops.oobbuf    = readbuf;
 			err = mtd_read_oob(mtd, addr, &ops);
+			if (mtd_is_bitflip(err))
+				err = 0;
+
 			if (err || ops.oobretlen != mtd->oobavail) {
 				pr_err("error: readoob failed at %#llx\n",
 						(long long)addr);
@@ -286,6 +292,9 @@ static int verify_eraseblock_in_one_go(int ebnum)
 
 	/* read entire block's OOB at one go */
 	err = mtd_read_oob(mtd, addr, &ops);
+	if (mtd_is_bitflip(err))
+		err = 0;
+
 	if (err || ops.oobretlen != len) {
 		pr_err("error: readoob failed at %#llx\n",
 		       (long long)addr);
@@ -527,6 +536,9 @@ static int __init mtd_oobtest_init(void)
 	pr_info("attempting to start read past end of OOB\n");
 	pr_info("an error is expected...\n");
 	err = mtd_read_oob(mtd, addr0, &ops);
+	if (mtd_is_bitflip(err))
+		err = 0;
+
 	if (err) {
 		pr_info("error occurred as expected\n");
 		err = 0;
@@ -571,6 +583,9 @@ static int __init mtd_oobtest_init(void)
 		pr_info("attempting to read past end of device\n");
 		pr_info("an error is expected...\n");
 		err = mtd_read_oob(mtd, mtd->size - mtd->writesize, &ops);
+		if (mtd_is_bitflip(err))
+			err = 0;
+
 		if (err) {
 			pr_info("error occurred as expected\n");
 			err = 0;
@@ -615,6 +630,9 @@ static int __init mtd_oobtest_init(void)
 		pr_info("attempting to read past end of device\n");
 		pr_info("an error is expected...\n");
 		err = mtd_read_oob(mtd, mtd->size - mtd->writesize, &ops);
+		if (mtd_is_bitflip(err))
+			err = 0;
+
 		if (err) {
 			pr_info("error occurred as expected\n");
 			err = 0;
@@ -684,6 +702,9 @@ static int __init mtd_oobtest_init(void)
 		ops.datbuf    = NULL;
 		ops.oobbuf    = readbuf;
 		err = mtd_read_oob(mtd, addr, &ops);
+		if (mtd_is_bitflip(err))
+			err = 0;
+
 		if (err)
 			goto out;
 		if (memcmpshow(addr, readbuf, writebuf,
-- 
2.14.1