[PATCH v2] powerpc/setup_64: fix -Wempty-body warnings

[PATCH v2] powerpc/setup_64: fix -Wempty-body warnings

[Qian Cai]

At the beginning of setup_64.c, it has,

  #ifdef DEBUG
  #define DBG(fmt...) udbg_printf(fmt)
  #else
  #define DBG(fmt...)
  #endif

where DBG() could be compiled away, and generate warnings,

arch/powerpc/kernel/setup_64.c: In function 'initialize_cache_info':
arch/powerpc/kernel/setup_64.c:579:49: warning: suggest braces around
empty body in an 'if' statement [-Wempty-body]
    DBG("Argh, can't find dcache properties !\n");
                                                 ^
arch/powerpc/kernel/setup_64.c:582:49: warning: suggest braces around
empty body in an 'if' statement [-Wempty-body]
    DBG("Argh, can't find icache properties !\n");

Suggested-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Signed-off-by: Qian Cai <cai@lca.pw>
---

v2: fix it by using a NOP while loop.

 arch/powerpc/kernel/setup_64.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 44b4c432a273..bed4ae8d338c 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -71,7 +71,7 @@
 #ifdef DEBUG
 #define DBG(fmt...) udbg_printf(fmt)
 #else
-#define DBG(fmt...)
+#define DBG(fmt...) do { } while (0)
 #endif
 
 int spinning_secondaries;
-- 
1.8.3.1

Re: [PATCH v2] powerpc/setup_64: fix -Wempty-body warnings

[Qian Cai]

Ping.

On Wed, 2019-06-05 at 16:53 -0400, Qian Cai wrote:
> At the beginning of setup_64.c, it has,
> 
>   #ifdef DEBUG
>   #define DBG(fmt...) udbg_printf(fmt)
>   #else
>   #define DBG(fmt...)
>   #endif
> 
> where DBG() could be compiled away, and generate warnings,
> 
> arch/powerpc/kernel/setup_64.c: In function 'initialize_cache_info':
> arch/powerpc/kernel/setup_64.c:579:49: warning: suggest braces around
> empty body in an 'if' statement [-Wempty-body]
>     DBG("Argh, can't find dcache properties !\n");
>                                                  ^
> arch/powerpc/kernel/setup_64.c:582:49: warning: suggest braces around
> empty body in an 'if' statement [-Wempty-body]
>     DBG("Argh, can't find icache properties !\n");
> 
> Suggested-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
> Signed-off-by: Qian Cai <cai@lca.pw>
> ---
> 
> v2: fix it by using a NOP while loop.
> 
>  arch/powerpc/kernel/setup_64.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
> index 44b4c432a273..bed4ae8d338c 100644
> --- a/arch/powerpc/kernel/setup_64.c
> +++ b/arch/powerpc/kernel/setup_64.c
> @@ -71,7 +71,7 @@
>  #ifdef DEBUG
>  #define DBG(fmt...) udbg_printf(fmt)
>  #else
> -#define DBG(fmt...)
> +#define DBG(fmt...) do { } while (0)
>  #endif
>  
>  int spinning_secondaries;

Re: [PATCH v2] powerpc/setup_64: fix -Wempty-body warnings

[Joe Perches]

On Thu, 2019-06-27 at 15:52 -0400, Qian Cai wrote:
> On Wed, 2019-06-05 at 16:53 -0400, Qian Cai wrote:
> > At the beginning of setup_64.c, it has,
> > 
> >   #ifdef DEBUG
> >   #define DBG(fmt...) udbg_printf(fmt)
> >   #else
> >   #define DBG(fmt...)
> >   #endif
> > 
> > where DBG() could be compiled away, and generate warnings,
> > 
> > arch/powerpc/kernel/setup_64.c: In function 'initialize_cache_info':
> > arch/powerpc/kernel/setup_64.c:579:49: warning: suggest braces around
> > empty body in an 'if' statement [-Wempty-body]
> >     DBG("Argh, can't find dcache properties !\n");
> >                                                  ^
> > arch/powerpc/kernel/setup_64.c:582:49: warning: suggest braces around
> > empty body in an 'if' statement [-Wempty-body]
> >     DBG("Argh, can't find icache properties !\n");
[]
> > diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
[]
> > @@ -71,7 +71,7 @@
> >  #ifdef DEBUG
> >  #define DBG(fmt...) udbg_printf(fmt)
> >  #else
> > -#define DBG(fmt...)
> > +#define DBG(fmt...) do { } while (0)

I suggest

#define DBG(fmt...) do { if (0) udbg_printf(fmt); } while (0)

so that format and argument are always verified by the compiler.

I would also prefer a more generic form using ##__VA_ARGS__

#ifdef DEBUG
#define DBG(fmt, ...) udbg_printf(fmt, ##__VA_ARGS__)
#else
#define DBG(fmt, ...) do { if (0) udbg_printf(fmt, ##__VA_ARGS__); } while (0)
#endif

or maybe use the no_printk macro like

#ifdef DEBUG
#define DBG(fmt, ...) udbg_printf(fmt, ##__VA_ARGS__)
#else
#define DBG(fmt, ...) no_printk(fmt, ##__VA_ARGS__)
#endif