[PATCH 1/8] arm/mach-tegra: fix unsigned calcs

[PATCH 1/8] arm/mach-tegra: fix unsigned calcs

[Kulikov Vasiliy]

divider_u71 is unsigned, so this check is buggy:
if (divider_u71 - 2 > 255 || divider_u71 - 2 < 0)

If divider_u71 is 0 or 1 both checks are lying.
So, it does not produce a buggy answer, but it is confusing.

Signed-off-by: Kulikov Vasiliy <segooon@gmail.com>
---
 arch/arm/mach-tegra/tegra2_clocks.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/arm/mach-tegra/tegra2_clocks.c b/arch/arm/mach-tegra/tegra2_clocks.c
index 4261632..64df5b4 100644
--- a/arch/arm/mach-tegra/tegra2_clocks.c
+++ b/arch/arm/mach-tegra/tegra2_clocks.c
@@ -149,7 +149,7 @@ static int clk_div71_get_divider(struct clk *c, unsigned long rate)
 
 	divider_u71 = DIV_ROUND_UP(c->rate * 2, rate);
 
-	if (divider_u71 - 2 > 255 || divider_u71 - 2 < 0)
+	if (divider_u71 > 2 + 255 || divider_u71 < 2)
 		return -EINVAL;
 
 	return divider_u71 - 2;
-- 
1.7.0.4

Re: [PATCH 1/8] arm/mach-tegra: fix unsigned calcs

[Colin Cross]

On Thu, Jul 15, 2010 at 11:43 AM, Kulikov Vasiliy <segooon@gmail.com> wrote:
> divider_u71 is unsigned, so this check is buggy:
> if (divider_u71 - 2 > 255 || divider_u71 - 2 < 0)
>
> If divider_u71 is 0 or 1 both checks are lying.
> So, it does not produce a buggy answer, but it is confusing.

Hi Kulikov,
Thanks for the patch.  This problem has been fixed in another patch in
the linux-tegra tree, I'll post it for review and update the
linux-next tree soon.

Colin Cross

Re: [PATCH 1/8] arm/mach-tegra: fix unsigned calcs

[Mike Rapoport]

Colin Cross wrote:
> On Thu, Jul 15, 2010 at 11:43 AM, Kulikov Vasiliy <segooon@gmail.com> wrote:
>> divider_u71 is unsigned, so this check is buggy:
>> if (divider_u71 - 2 > 255 || divider_u71 - 2 < 0)
>>
>> If divider_u71 is 0 or 1 both checks are lying.
>> So, it does not produce a buggy answer, but it is confusing.
> 
> Hi Kulikov,

The first name is Vasiliy :)

> Thanks for the patch.  This problem has been fixed in another patch in
> the linux-tegra tree, I'll post it for review and update the
> linux-next tree soon.
> 
> Colin Cross
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel


-- 
Sincerely yours,
Mike.