linux-kernel - Re: [PATCH] drm: powerplay: use div64_s64 instead of do

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <568A6A19.7060309@amd.com>
Date:	Mon, 4 Jan 2016 13:48:25 +0100
From:	Christian König <christian.koenig@....com>
To:	Arnd Bergmann <arnd@...db.de>, Jammy Zhou <Jammy.Zhou@....com>,
	"David Airlie" <airlied@...ux.ie>
CC:	Eric Huang <JinHuiEric.Huang@....com>,
	Alex Deucher <alexander.deucher@....com>,
	David Zhang <david1.zhang@....com>,
	<linux-kernel@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>
Subject: Re: [PATCH] drm: powerplay: use div64_s64 instead of do_div

On 01.01.2016 14:07, Arnd Bergmann wrote:
> The newly added code for Fiji creates a correct compiler warning
> about invalid use of the do_div macro:
>
> In file included from powerplay/hwmgr/ppatomctrl.c:31:0:
> drivers/gpu/drm/amd/amdgpu/../powerplay/hwmgr/ppevvmath.h: In function 'fDivide':
> drivers/gpu/drm/amd/amdgpu/../powerplay/hwmgr/ppevvmath.h:382:89: warning: comparison of distinct pointer types lacks a cast
>       do_div(longlongX, longlongY); /*Q(32,32) divided by Q(16,16) = Q(16,16) Back to original format */
>
> do_div() divides an unsigned 64-bit number by an unsigned 32-bit number.
> The code instead wants to divide two signed 64-bit numbers, which is done
> using the div64_s64 function.
>
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

Reviewed-by: Christian König <christian.koenig@....com>

> Fixes: 770911a3cfbb ("drm/amd/powerplay: add/update headers for Fiji SMU and DPM")
> ---
> Found on ARM allmodconfig on yesterday's linux-next
>
> diff --git a/drivers/gpu/drm/amd/powerplay/hwmgr/ppevvmath.h b/drivers/gpu/drm/amd/powerplay/hwmgr/ppevvmath.h
> index 42f2423cddea..411cb0fcdf98 100644
> --- a/drivers/gpu/drm/amd/powerplay/hwmgr/ppevvmath.h
> +++ b/drivers/gpu/drm/amd/powerplay/hwmgr/ppevvmath.h
> @@ -379,7 +379,7 @@ fInt fDivide (fInt X, fInt Y)
>   
>       longlongX = longlongX << 16; /*Q(16,16) -> Q(32,32) */
>   
> -    do_div(longlongX, longlongY); /*Q(32,32) divided by Q(16,16) = Q(16,16) Back to original format */
> +    div64_s64(longlongX, longlongY); /*Q(32,32) divided by Q(16,16) = Q(16,16) Back to original format */
>   
>       fQuotient.full = (int)longlongX;
>       return fQuotient;
>

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/