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

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Message-ID: <20200217121717.2152db2c@collabora.com>
Date:   Mon, 17 Feb 2020 12:17:17 +0100
From:   Boris Brezillon <boris.brezillon@...labora.com>
To:     Schrempf Frieder <frieder.schrempf@...tron.de>
Cc:     Boris Brezillon <bbrezillon@...nel.org>,
        Jeff Kletsky <git-commits@...ycomm.com>,
        liaoweixiong <liaoweixiong@...winnertech.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Peter Pan <peterpandong@...ron.com>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        "Richard Weinberger" <richard@....at>
Subject: Re: [PATCH 1/3] mtd: spinand: Stop using spinand->oobbuf for
 buffering bad block markers

On Tue, 11 Feb 2020 16:35:33 +0000
Schrempf Frieder <frieder.schrempf@...tron.de> wrote:

> From: Frieder Schrempf <frieder.schrempf@...tron.de>
> 
> 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 MEM 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@...r.kernel.org
> Signed-off-by: Frieder Schrempf <frieder.schrempf@...tron.de>
> ---
>  drivers/mtd/nand/spi/core.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
> index 89f6beefb01c..5d267a67a5f7 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[] = { 0, 0 };

How about

	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[] = { 0, 0 };
>  	struct nand_page_io_req req = {
>  		.pos = *pos,
>  		.ooboffs = 0,
>  		.ooblen = 2,
> -		.oobbuf.out = spinand->oobbuf,
> +		.oobbuf.out = marker,

Ditto.

>  	};
>  	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);
>  }
>  

With these minor things addressed

Reviewed-by: Boris Brezillon <boris.brezillon@...labora.com>