linux-kernel - Re: [PATCH 1/5] mtd: brcmnand: Fix pointer type-cast in brcmnand

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Message-ID: <20151012212015.GO107187@google.com>
Date:	Mon, 12 Oct 2015 14:20:15 -0700
From:	Brian Norris <computersforpeace@...il.com>
To:	Anup Patel <anup.patel@...adcom.com>
Cc:	linux-arm-kernel@...ts.infradead.org,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	David Woodhouse <dwmw2@...radead.org>,
	Ray Jui <rjui@...adcom.com>,
	Scott Branden <sbranden@...adcom.com>,
	Florian Fainelli <f.fainelli@...il.com>,
	Pramod KUMAR <pramodku@...adcom.com>,
	Vikram Prakash <vikramp@...adcom.com>,
	Sandeep Tripathy <tripathy@...adcom.com>,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-mtd@...ts.infradead.org,
	bcm-kernel-feedback-list@...adcom.com
Subject: Re: [PATCH 1/5] mtd: brcmnand: Fix pointer type-cast in
 brcmnand_write()

On Fri, Oct 02, 2015 at 11:26:42PM +0530, Anup Patel wrote:
> We should always type-cast pointer to "long" or "unsigned long"
> because size of pointer is same as machine word size. This will
> avoid pointer type-cast issues on both 32bit and 64bit systems.
> 
> This patch fixes pointer type-cast issue in brcmnand_write()
> as-per above info.
> 
> Signed-off-by: Anup Patel <anup.patel@...adcom.com>
> Reviewed-by: Vikram Prakash <vikramp@...adcom.com>
> Reviewed-by: Ray Jui <rjui@...adcom.com>
> Reviewed-by: Scott Branden <sbranden@...adcom.com>
> ---
>  drivers/mtd/nand/brcmnand/brcmnand.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/nand/brcmnand/brcmnand.c b/drivers/mtd/nand/brcmnand/brcmnand.c
> index fddb795..4cba03d 100644
> --- a/drivers/mtd/nand/brcmnand/brcmnand.c
> +++ b/drivers/mtd/nand/brcmnand/brcmnand.c
> @@ -1544,9 +1544,9 @@ static int brcmnand_write(struct mtd_info *mtd, struct nand_chip *chip,
>  
>  	dev_dbg(ctrl->dev, "write %llx <- %p\n", (unsigned long long)addr, buf);
>  
> -	if (unlikely((u32)buf & 0x03)) {
> +	if (unlikely((unsigned long)buf & 0x03)) {
>  		dev_warn(ctrl->dev, "unaligned buffer: %p\n", buf);
> -		buf = (u32 *)((u32)buf & ~0x03);
> +		buf = (u32 *)((unsigned long)buf & ~0x03);
>  	}

Hmm, this block isn't really good. We should probably work to remove
this. Not sure why I left that in, actually. At a minimum, it'd probably
good to make this noisier, so if we see this in practice, we can work to
fix those cases.

But anyway, the patch is good (though 'uintptr_t' might be slightly
better), so pushed to l2-mtd.git.

Brian

>  
>  	brcmnand_wp(mtd, 0);
> -- 
> 1.9.1
> 
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