linux-kernel - Re: [PATCH v1 3/3] lib/vsprintf: Force type of flags for gfp

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Date:   Fri, 31 Jul 2020 11:34:50 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        linux-kernel@...r.kernel.org,
        Rasmus Villemoes <linux@...musvillemoes.dk>
Subject: Re: [PATCH v1 3/3] lib/vsprintf: Force type of flags for gfp_t

On Fri, 31 Jul 2020 15:31:45 +0300
Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:

> Sparse is not happy about restricted type being assigned:
>   lib/vsprintf.c:1940:23: warning: incorrect type in assignment (different base types)
>   lib/vsprintf.c:1940:23:    expected unsigned long [assigned] flags
>   lib/vsprintf.c:1940:23:    got restricted gfp_t [usertype]
> 
> Force type of flags to make sparse happy.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  lib/vsprintf.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index 90d818ef03c5..118e2727d058 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -1937,7 +1937,7 @@ char *flags_string(char *buf, char *end, void *flags_ptr,
>  		names = vmaflag_names;
>  		break;
>  	case 'g':
> -		flags = *(gfp_t *)flags_ptr;
> +		flags = (__force typeof(flags))(*(gfp_t *)flags_ptr);

Do we really need to say "typeof(flags)" ? What about simply using
flags' type?

		flags = (__force unsigned long)(*(gfp_t *)flags_ptr);

?

I mean, it's not like flags is a global. It's defined a few lines above.

-- Steve


>  		names = gfpflag_names;
>  		break;
>  	default: