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References: <20240516174357.26755-1-jim.cromie@gmail.com> <20240516174357.26755-5-jim.cromie@gmail.com>
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From: =?UTF-8?Q?=C5=81ukasz_Bartosik?= <ukaszb@chromium.org>
Date: Tue, 21 May 2024 13:42:04 +0200
Message-ID: <CALwA+NZP7OkAh3_h+bk_iKosBmbshvMfwU58JVjRwG46XevXSQ@mail.gmail.com>
Subject: Re: [PATCH v8-RESEND 04/33] dyndbg: make ddebug_class_param union
 members same size
To: Jim Cromie <jim.cromie@gmail.com>
Cc: jbaron@akamai.com, gregkh@linuxfoundation.org, 
	linux-kernel@vger.kernel.org, linux@rasmusvillemoes.dk, joe@perches.com, 
	mcgrof@kernel.org, daniel.vetter@ffwll.ch, tvrtko.ursulin@linux.intel.com, 
	jani.nikula@intel.com, ville.syrjala@linux.intel.com, seanpaul@chromium.org, 
	robdclark@gmail.com, groeck@google.com, yanivt@google.com, bleung@google.com
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On Thu, May 16, 2024 at 7:44=E2=80=AFPM Jim Cromie <jim.cromie@gmail.com> w=
rote:
>
> struct ddebug_class_param keeps a ref to the state-storage of the
> param; make both class-types use the same unsigned long storage type.
> ISTM this is simpler and safer.

Why is it safer for members of a union to have the same size ?


>
> Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
> ---
>  include/linux/dynamic_debug.h | 2 +-
>  lib/dynamic_debug.c           | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.=
h
> index 4fcbf4d4fd0a..5231aaf361c4 100644
> --- a/include/linux/dynamic_debug.h
> +++ b/include/linux/dynamic_debug.h
> @@ -124,7 +124,7 @@ struct _ddebug_info {
>  struct ddebug_class_param {
>         union {
>                 unsigned long *bits;
> -               unsigned int *lvl;
> +               unsigned long *lvl;
>         };
>         char flags[8];
>         const struct ddebug_class_map *map;
> diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
> index 73ccf947d4aa..152b04c05981 100644
> --- a/lib/dynamic_debug.c
> +++ b/lib/dynamic_debug.c
> @@ -799,7 +799,7 @@ int param_get_dyndbg_classes(char *buffer, const stru=
ct kernel_param *kp)
>
>         case DD_CLASS_TYPE_LEVEL_NAMES:
>         case DD_CLASS_TYPE_LEVEL_NUM:
> -               return scnprintf(buffer, PAGE_SIZE, "%d\n", *dcp->lvl);
> +               return scnprintf(buffer, PAGE_SIZE, "%ld\n", *dcp->lvl);
>         default:
>                 return -1;
>         }
> --
> 2.45.0
>