linux-kernel - Re: [PATCH 1/1] kernel/profile.c: use static const char instead of static char

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Message-Id: <20140507153050.70ad69194684f452bacc9bc8@linux-foundation.org>
Date:	Wed, 7 May 2014 15:30:50 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Fabian Frederick <fabf@...net.be>
Cc:	linux-kernel <linux-kernel@...r.kernel.org>,
	Paul Gortmaker <paul.gortmaker@...driver.com>
Subject: Re: [PATCH 1/1] kernel/profile.c: use static const char instead of
 static char

On Wed, 7 May 2014 22:35:08 +0200 Fabian Frederick <fabf@...net.be> wrote:

> schedstr, sleepstr and kvmstr are only used in strcmp & strlen
> 
> ...
>
> --- a/kernel/profile.c
> +++ b/kernel/profile.c
> @@ -52,9 +52,9 @@ static DEFINE_MUTEX(profile_flip_mutex);
>  
>  int profile_setup(char *str)
>  {
> -	static char schedstr[] = "schedule";
> -	static char sleepstr[] = "sleep";
> -	static char kvmstr[] = "kvm";
> +	static const char schedstr[] = "schedule";
> +	static const char sleepstr[] = "sleep";
> +	static const char kvmstr[] = "kvm";
>  	int par;
>  

I'd expect this to either make no change or to make text larger and
data smaller.

In fact,

   text    data     bss     dec     hex filename
   7631     811    3016   11458    2cc2 kernel/profile.o-before
   7520     779    3016   11315    2c33 kernel/profile.o-after

Both text and data got smaller and the total reduction was a whopping
143 bytes.   Weirdness.

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