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

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

[Fabian Frederick]

schedstr, sleepstr and kvmstr are only used in strcmp & strlen

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Fabian Frederick <fabf@skynet.be>
---
 kernel/profile.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/profile.c b/kernel/profile.c
index cb980f0..f8132a2 100644
--- 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;
 
 	if (!strncmp(str, sleepstr, strlen(sleepstr))) {
-- 
1.8.4.5

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

[Andrew Morton]

On Wed, 7 May 2014 22:35:08 +0200 Fabian Frederick <fabf@skynet.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.

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

[Joe Perches]

On Wed, 2014-05-07 at 15:30 -0700, Andrew Morton wrote:
> On Wed, 7 May 2014 22:35:08 +0200 Fabian Frederick <fabf@skynet.be> wrote:
> > schedstr, sleepstr and kvmstr are only used in strcmp & strlen
[]
> > +++ 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.

Now there's no code required to initialize/memcpy
the strings every function invocation.