linux-kernel - Re: [PATCH 1/2] mtd: nand: omap: Do not use global variables

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Message-ID: <542CF446.6090608@ti.com>
Date:	Thu, 2 Oct 2014 09:44:22 +0300
From:	Roger Quadros <rogerq@...com>
To:	Rostislav Lisovy <lisovy@...il.com>,
	David Woodhouse <dwmw2@...radead.org>,
	Brian Norris <computersforpeace@...il.com>,
	pekon <pekon@...-sem.com>, Tony Lindgren <tony@...mide.com>,
	<linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
CC:	<michal.vokac@...ap.cz>, <sojkam1@....cvut.cz>,
	Rostislav Lisovy <lisovy@...ica.cz>
Subject: Re: [PATCH 1/2] mtd: nand: omap: Do not use global variables

Hi,

On 10/01/2014 05:59 PM, Rostislav Lisovy wrote:
> Since the commit 97a288ba2cfa ("ARM: omap2+: gpmc-nand: Use
> dynamic platform_device_alloc()") gpmc-nand driver supports
> multiple NAND flash devices connected to the single controller.
> Remove global variable to make the code thread-safe.
> 
> Signed-off-by: Rostislav Lisovy <lisovy@...ica.cz>
> ---
>  drivers/mtd/nand/omap2.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c
> index 5967b38..24d5c6a 100644
> --- a/drivers/mtd/nand/omap2.c
> +++ b/drivers/mtd/nand/omap2.c
> @@ -146,8 +146,6 @@ static u_char bch8_vector[] = {0xf3, 0xdb, 0x14, 0x16, 0x8b, 0xd2, 0xbe, 0xcc,
>  static u_char bch4_vector[] = {0x00, 0x6b, 0x31, 0xdd, 0x41, 0xbc, 0x10};
>  #endif
>  
> -/* oob info generated runtime depending on ecc algorithm and layout selected */
> -static struct nand_ecclayout omap_oobinfo;
>  
>  struct omap_nand_info {
>  	struct nand_hw_control		controller;
> @@ -1794,7 +1792,7 @@ static int omap_nand_probe(struct platform_device *pdev)
>  	}
>  
>  	/* populate MTD interface based on ECC scheme */
> -	ecclayout		= &omap_oobinfo;
> +	ecclayout		= kzalloc(sizeof(*ecclayout), GFP_KERNEL);

We should free this in failure path or omap_nand_remove(), or use devm_kzalloc().

How about making "struct nand_ecclayout" a part of omap_nand_info, so that it gets allocated
without a separate devm_kzalloc() call?

>  	switch (info->ecc_opt) {
>  	case OMAP_ECC_HAM1_CODE_SW:
>  		nand_chip->ecc.mode = NAND_ECC_SOFT;
> 

cheers,
-roger
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