From mboxrd@z Thu Jan  1 00:00:00 1970
From: t.figa@samsung.com (Tomasz Figa)
Date: Thu, 15 May 2014 18:51:10 +0200
Subject: [PATCH] clk: divider: Fix overflow in clk_divider_bestdiv
In-Reply-To: <1399479850-25292-1-git-send-email-t.figa@samsung.com>
References: <1399479850-25292-1-git-send-email-t.figa@samsung.com>
Message-ID: <5374F07E.9070106@samsung.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

Hi Mike,

On 07.05.2014 18:24, Tomasz Figa wrote:
> Commit c686078 ("clk: divider: Add round to closest divider") introduced
> a helper function to check whether given divisor is the best one instead
> of direct check. However due to int type used instead of unsigned long
> for passing calculated rates to this function in certain cases an
> overflow could occur, for example when trying to obtain maximum possible
> clock rate by calling clk_round_rate(..., UINT_MAX).
> 
> This patch fixes this issue by changing the type of rate, now and best
> arguments of the function to unsigned long, which is the type that
> should be used for clock rates.
> 
> Signed-off-by: Tomasz Figa <t.figa@samsung.com>
> ---
>  drivers/clk/clk-divider.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
> index c572945..e0b360a 100644
> --- a/drivers/clk/clk-divider.c
> +++ b/drivers/clk/clk-divider.c
> @@ -232,7 +232,7 @@ static int _div_round(struct clk_divider *divider, unsigned long parent_rate,
>  }
>  
>  static bool _is_best_div(struct clk_divider *divider,
> -		int rate, int now, int best)
> +		unsigned long rate, unsigned long now, unsigned long best)
>  {
>  	if (divider->flags & CLK_DIVIDER_ROUND_CLOSEST)
>  		return abs(rate - now) < abs(rate - best);
> 

Ping. It's quite important fix as the issue makes all Exynos boards
using sdhci-s3c almost unusable.

Best regards,
Tomasz