[PATCH -next] mm: fix set but not used warning

[PATCH -next] mm: fix set but not used warning

[YueHaibing]

Fixes gcc '-Wunused-but-set-variable' warning:

lib/ioremap.c: In function 'ioremap_page_range':
lib/ioremap.c:203:16: warning:
 variable 'start' set but not used [-Wunused-but-set-variable]

flush_cache_vmap may no need param, so add __maybe_unused fix this warning.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
---
 lib/ioremap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/ioremap.c b/lib/ioremap.c
index 063213685563..d1c7a488e731 100644
--- a/lib/ioremap.c
+++ b/lib/ioremap.c
@@ -200,7 +200,7 @@ int ioremap_page_range(unsigned long addr,
 		       unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
 {
 	pgd_t *pgd;
-	unsigned long start;
+	unsigned long __maybe_unused start;
 	unsigned long next;
 	int err;

Re: [PATCH -next] mm: fix set but not used warning

[Kani, Toshi]

On Mon, 2019-02-18 at 13:57 +0000, YueHaibing wrote:
> Fixes gcc '-Wunused-but-set-variable' warning:
> 
> lib/ioremap.c: In function 'ioremap_page_range':
> lib/ioremap.c:203:16: warning:
>  variable 'start' set but not used [-Wunused-but-set-variable]
> 
> flush_cache_vmap may no need param, so add __maybe_unused fix this warning.

I think flush_cache_vmap should have a proper prototype with
__maybe_unused for its args.  But, there are so many arch-specific
definitions at glace, and I am not sure how manageable such change is,
though...

Thanks,
-Toshi

> 
> Signed-off-by: YueHaibing <yuehaibing@huawei.com>
> ---
>  lib/ioremap.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/ioremap.c b/lib/ioremap.c
> index 063213685563..d1c7a488e731 100644
> --- a/lib/ioremap.c
> +++ b/lib/ioremap.c
> @@ -200,7 +200,7 @@ int ioremap_page_range(unsigned long addr,
>  		       unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
>  {
>  	pgd_t *pgd;
> -	unsigned long start;
> +	unsigned long __maybe_unused start;
>  	unsigned long next;
>  	int err;
> 
> 
> 

Re: [PATCH -next] mm: fix set but not used warning

[Andrew Morton]

On Tue, 19 Feb 2019 18:28:30 +0000 "Kani, Toshi" <toshi.kani@hpe.com> wrote:

> On Mon, 2019-02-18 at 13:57 +0000, YueHaibing wrote:
> > Fixes gcc '-Wunused-but-set-variable' warning:
> > 
> > lib/ioremap.c: In function 'ioremap_page_range':
> > lib/ioremap.c:203:16: warning:
> >  variable 'start' set but not used [-Wunused-but-set-variable]
> > 
> > flush_cache_vmap may no need param, so add __maybe_unused fix this warning.
> 
> I think flush_cache_vmap should have a proper prototype with
> __maybe_unused for its args.  But, there are so many arch-specific
> definitions at glace, and I am not sure how manageable such change is,
> though...

This is one of the reasons why things like flush_cache_vmap() should
be implemented as static inline C functions, not as macros.