[PATCH v3 1/3] mtd: spinand: Stop using spinand->oobbuf for buffering bad block markers

[Schrempf Frieder]

From: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>

For reading and writing the bad block markers, spinand->oobbuf is
currently used as a buffer for the marker bytes. During the
underlying read and write operations to actually get/set the content
of the OOB area, the content of spinand->oobbuf is reused and changed
by accessing it through spinand->oobbuf and/or spinand->databuf.

This is a flaw in the original design of the SPI NAND core and at the
latest from 13c15e07eedf ("mtd: spinand: Handle the case where
PROGRAM LOAD does not reset the cache") on, it results in not having
the bad block marker written at all, as the spinand->oobbuf is
cleared to 0xff after setting the marker bytes to zero.

To fix it, we now just store the two bytes for the marker on the
stack and let the read/write operations copy it from/to the page
buffer later.

Fixes: 7529df465248 ("mtd: nand: Add core infrastructure to support SPI NANDs")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>
Reviewed-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
---
Changes in v3:
 * Correct "SPI MEM" to "SPI NAND" in commit message

Changes in v2:
 * Incorporate small improvements proposed by Boris
 * Add Boris' R-b tag
---
 drivers/mtd/nand/spi/core.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
index 89f6beefb01c..de36cd7a5d7e 100644
--- a/drivers/mtd/nand/spi/core.c
+++ b/drivers/mtd/nand/spi/core.c
@@ -568,18 +568,18 @@ static int spinand_mtd_write(struct mtd_info *mtd, loff_t to,
 static bool spinand_isbad(struct nand_device *nand, const struct nand_pos *pos)
 {
 	struct spinand_device *spinand = nand_to_spinand(nand);
+	u8 marker[2] = { };
 	struct nand_page_io_req req = {
 		.pos = *pos,
-		.ooblen = 2,
+		.ooblen = sizeof(marker),
 		.ooboffs = 0,
-		.oobbuf.in = spinand->oobbuf,
+		.oobbuf.in = marker,
 		.mode = MTD_OPS_RAW,
 	};
 
-	memset(spinand->oobbuf, 0, 2);
 	spinand_select_target(spinand, pos->target);
 	spinand_read_page(spinand, &req, false);
-	if (spinand->oobbuf[0] != 0xff || spinand->oobbuf[1] != 0xff)
+	if (marker[0] != 0xff || marker[1] != 0xff)
 		return true;
 
 	return false;
@@ -603,11 +603,12 @@ static int spinand_mtd_block_isbad(struct mtd_info *mtd, loff_t offs)
 static int spinand_markbad(struct nand_device *nand, const struct nand_pos *pos)
 {
 	struct spinand_device *spinand = nand_to_spinand(nand);
+	u8 marker[2] = { };
 	struct nand_page_io_req req = {
 		.pos = *pos,
 		.ooboffs = 0,
-		.ooblen = 2,
-		.oobbuf.out = spinand->oobbuf,
+		.ooblen = sizeof(marker),
+		.oobbuf.out = marker,
 	};
 	int ret;
 
@@ -622,7 +623,6 @@ static int spinand_markbad(struct nand_device *nand, const struct nand_pos *pos)
 
 	spinand_erase_op(spinand, pos);
 
-	memset(spinand->oobbuf, 0, 2);
 	return spinand_write_page(spinand, &req);
 }
 
-- 
2.17.1