linux-kernel - Re: [PATCH] kernel: Fix ftrace.c compiler warning when calling ftrace_nop

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Message-ID: <BANLkTi=fuEzCUnK0Vuc-2WAnKUxEyG_VWw@mail.gmail.com>
Date:	Sun, 22 May 2011 22:27:35 -0400
From:	Eduardo Silva <edsiper@...il.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Steven Rostedt <rostedt@...dmis.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kernel: Fix ftrace.c compiler warning when calling ftrace_nop_replace()

On Sun, May 22, 2011 at 9:36 PM, H. Peter Anvin <hpa@...or.com> wrote:
> On 05/22/2011 06:19 PM, Eduardo Silva wrote:
>> the function ftrace_nop_replace() returns a 'static const unsigned char *'
>> value, so when the caller perform a direct assignment to a
>> 'static unsigned char *', the compiler raise the following warning message:
>>
>>  ftrace.c:308:6: warning: assignment discards qualifiers from pointer target type
>>  ftrace.c:318:6: warning: assignment discards qualifiers from pointer target type
>>
>> Adding the proper casts the message goes away.
>>
>> Signed-off-by: Eduardo Silva <edsiper@...il.com>
>
> This quiets a warning of something that potentially looks like a real
> bug.  Perhaps "new" should be const?

The value is returned in the following function:

static const unsigned char *ftrace_nop_replace(void)
{
	return ideal_nops[NOP_ATOMIC5];
}

ideal_nops seems to be constant and architecture dependent, so make
sense to return it as a constant pointer... i think that we need more
comments about it.

regards,



>
>        -hpa
>
>
> --
> H. Peter Anvin, Intel Open Source Technology Center
> I work for Intel.  I don't speak on their behalf.
>
>



-- 
Eduardo Silva
http://edsiper.linuxchile.cl
http://www.monkey-project.com
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