[PATCH] asm-generic: percpu: avoid Wshadow warning

[PATCH] asm-generic: percpu: avoid Wshadow warning

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

Nesting macros that use the same local variable names causes
warnings when building with "make W=2":

include/asm-generic/percpu.h:117:14: warning: declaration of '__ret' shadows a previous local [-Wshadow]
include/asm-generic/percpu.h:126:14: warning: declaration of '__ret' shadows a previous local [-Wshadow]

These are fairly harmless, but since the warning comes from
a global header, the warning happens every time the headers
are included, which is fairly annoying.

Rename the variables to avoid shadowing and shut up the warning.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 include/asm-generic/percpu.h | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/include/asm-generic/percpu.h b/include/asm-generic/percpu.h
index 35e4a53b83e6..6432a7fade91 100644
--- a/include/asm-generic/percpu.h
+++ b/include/asm-generic/percpu.h
@@ -114,21 +114,21 @@ do {									\
 
 #define __this_cpu_generic_read_nopreempt(pcp)				\
 ({									\
-	typeof(pcp) __ret;						\
+	typeof(pcp) ___ret;						\
 	preempt_disable_notrace();					\
-	__ret = READ_ONCE(*raw_cpu_ptr(&(pcp)));			\
+	___ret = READ_ONCE(*raw_cpu_ptr(&(pcp)));			\
 	preempt_enable_notrace();					\
-	__ret;								\
+	___ret;								\
 })
 
 #define __this_cpu_generic_read_noirq(pcp)				\
 ({									\
-	typeof(pcp) __ret;						\
-	unsigned long __flags;						\
-	raw_local_irq_save(__flags);					\
-	__ret = raw_cpu_generic_read(pcp);				\
-	raw_local_irq_restore(__flags);					\
-	__ret;								\
+	typeof(pcp) ___ret;						\
+	unsigned long ___flags;						\
+	raw_local_irq_save(___flags);					\
+	___ret = raw_cpu_generic_read(pcp);				\
+	raw_local_irq_restore(___flags);				\
+	___ret;								\
 })
 
 #define this_cpu_generic_read(pcp)					\
-- 
2.27.0

Re: [PATCH] asm-generic: percpu: avoid Wshadow warning

[Luc Van Oostenryck]

On Mon, Oct 26, 2020 at 04:53:48PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> Nesting macros that use the same local variable names causes
> warnings when building with "make W=2":
> 
> include/asm-generic/percpu.h:117:14: warning: declaration of '__ret' shadows a previous local [-Wshadow]
> include/asm-generic/percpu.h:126:14: warning: declaration of '__ret' shadows a previous local [-Wshadow]
> 
> These are fairly harmless, but since the warning comes from
> a global header, the warning happens every time the headers
> are included, which is fairly annoying.
> 
> Rename the variables to avoid shadowing and shut up the warning.

Looks good to me. Fell free to add my:

Reviewed-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>

Re: [PATCH] asm-generic: percpu: avoid Wshadow warning

[Dennis Zhou]

Hello,

On Mon, Oct 26, 2020 at 04:53:48PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> Nesting macros that use the same local variable names causes
> warnings when building with "make W=2":
> 
> include/asm-generic/percpu.h:117:14: warning: declaration of '__ret' shadows a previous local [-Wshadow]
> include/asm-generic/percpu.h:126:14: warning: declaration of '__ret' shadows a previous local [-Wshadow]
> 
> These are fairly harmless, but since the warning comes from
> a global header, the warning happens every time the headers
> are included, which is fairly annoying.
> 
> Rename the variables to avoid shadowing and shut up the warning.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  include/asm-generic/percpu.h | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
> 
> diff --git a/include/asm-generic/percpu.h b/include/asm-generic/percpu.h
> index 35e4a53b83e6..6432a7fade91 100644
> --- a/include/asm-generic/percpu.h
> +++ b/include/asm-generic/percpu.h
> @@ -114,21 +114,21 @@ do {									\
>  
>  #define __this_cpu_generic_read_nopreempt(pcp)				\
>  ({									\
> -	typeof(pcp) __ret;						\
> +	typeof(pcp) ___ret;						\
>  	preempt_disable_notrace();					\
> -	__ret = READ_ONCE(*raw_cpu_ptr(&(pcp)));			\
> +	___ret = READ_ONCE(*raw_cpu_ptr(&(pcp)));			\
>  	preempt_enable_notrace();					\
> -	__ret;								\
> +	___ret;								\
>  })
>  
>  #define __this_cpu_generic_read_noirq(pcp)				\
>  ({									\
> -	typeof(pcp) __ret;						\
> -	unsigned long __flags;						\
> -	raw_local_irq_save(__flags);					\
> -	__ret = raw_cpu_generic_read(pcp);				\
> -	raw_local_irq_restore(__flags);					\
> -	__ret;								\
> +	typeof(pcp) ___ret;						\
> +	unsigned long ___flags;						\
> +	raw_local_irq_save(___flags);					\
> +	___ret = raw_cpu_generic_read(pcp);				\
> +	raw_local_irq_restore(___flags);				\
> +	___ret;								\
>  })
>  
>  #define this_cpu_generic_read(pcp)					\
> -- 
> 2.27.0
> 

I've applied this to percpu#for-5.10-fixes.

Thanks,
Dennis