linux-kernel - [PATCH 3.16 119/410] mtd: nand: Fix nand_do_read

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Message-ID: <lsq.1528380321.996482940@decadent.org.uk>
Date:   Thu, 07 Jun 2018 15:05:21 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Miquel Raynal" <miquel.raynal@...e-electrons.com>,
        "Boris Brezillon" <boris.brezillon@...e-electrons.com>
Subject: [PATCH 3.16 119/410] mtd: nand: Fix nand_do_read_oob() return value

3.16.57-rc1 review patch.  If anyone has any objections, please let me know.

------------------

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

commit 87e89ce8d0d14f573c068c61bec2117751fb5103 upstream.

Starting from commit 041e4575f034 ("mtd: nand: handle ECC errors in
OOB"), nand_do_read_oob() (from the NAND core) did return 0 or a
negative error, and the MTD layer expected it.

However, the trend for the NAND layer is now to return an error or a
positive number of bitflips. Deciding which status to return to the user
belongs to the MTD layer.

Commit e47f68587b82 ("mtd: check for max_bitflips in mtd_read_oob()")
brought this logic to the mtd_read_oob() function while the return value
coming from nand_do_read_oob() (called by the ->_read_oob() hook) was
left unchanged.

Fixes: e47f68587b82 ("mtd: check for max_bitflips in mtd_read_oob()")
Signed-off-by: Miquel Raynal <miquel.raynal@...e-electrons.com>
Signed-off-by: Boris Brezillon <boris.brezillon@...e-electrons.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/mtd/nand/nand_base.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -1837,6 +1837,7 @@ static int nand_write_oob_syndrome(struc
 static int nand_do_read_oob(struct mtd_info *mtd, loff_t from,
 			    struct mtd_oob_ops *ops)
 {
+	unsigned int max_bitflips = 0;
 	int page, realpage, chipnr;
 	struct nand_chip *chip = mtd->priv;
 	struct mtd_ecc_stats stats;
@@ -1897,6 +1898,8 @@ static int nand_do_read_oob(struct mtd_i
 				nand_wait_ready(mtd);
 		}
 
+		max_bitflips = max_t(unsigned int, max_bitflips, ret);
+
 		readlen -= len;
 		if (!readlen)
 			break;
@@ -1922,7 +1925,7 @@ static int nand_do_read_oob(struct mtd_i
 	if (mtd->ecc_stats.failed - stats.failed)
 		return -EBADMSG;
 
-	return  mtd->ecc_stats.corrected - stats.corrected ? -EUCLEAN : 0;
+	return max_bitflips;
 }
 
 /**