linux-kernel - Re: [PATCH] powerpc: silence unused-but-set-variable warnings

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Date:   Thu, 7 Mar 2019 06:34:39 +0000
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Qian Cai <cai@....pw>, benh@...nel.crashing.org, paulus@...ba.org,
        mpe@...erman.id.au
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] powerpc: silence unused-but-set-variable warnings



On 03/07/2019 03:48 AM, Qian Cai wrote:
> pte_unmap() compiles away on some powerpc platforms, so silence the
> warnings below by using the argument to pte_unmap() as a nop. Also, fix
> checkpatch.pl warnings "Single statement macros should not use a do {}
> while (0) loop".
> 
> mm/memory.c: In function 'copy_pte_range':
> mm/memory.c:820:24: warning: variable 'orig_dst_pte' set but not used
> [-Wunused-but-set-variable]
> mm/memory.c:820:9: warning: variable 'orig_src_pte' set but not used
> [-Wunused-but-set-variable]
> mm/madvise.c: In function 'madvise_free_pte_range':
> mm/madvise.c:318:9: warning: variable 'orig_pte' set but not used
> [-Wunused-but-set-variable]
> mm/swap_state.c: In function 'swap_ra_info':
> mm/swap_state.c:634:15: warning: variable 'orig_pte' set but not used
> [-Wunused-but-set-variable]
> 
> Signed-off-by: Qian Cai <cai@....pw>
> ---
>   arch/powerpc/include/asm/book3s/64/pgtable.h | 2 +-
>   arch/powerpc/include/asm/nohash/64/pgtable.h | 2 +-
>   2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
> index 868fcaf56f6b..ec00ce6dd312 100644
> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
> @@ -1006,7 +1006,7 @@ extern struct page *pgd_page(pgd_t pgd);
>   	(((pte_t *) pmd_page_vaddr(*(dir))) + pte_index(addr))
>   
>   #define pte_offset_map(dir,addr)	pte_offset_kernel((dir), (addr))
> -#define pte_unmap(pte)			do { } while(0)
> +#define pte_unmap(pte)			(void)(pte)

I think it would be better with a static inline

--- a/arch/powerpc/include/asm/nohash/64/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/64/pgtable.h
@@ -205,7 +205,8 @@ static inline void pgd_set(pgd_t *pgdp, unsigned 
long val)
    (((pte_t *) pmd_page_vaddr(*(dir))) + (((addr) >> PAGE_SHIFT) & 
(PTRS_PER_PTE - 1)))

  #define pte_offset_map(dir,addr)	pte_offset_kernel((dir), (addr))
-#define pte_unmap(pte)			do { } while(0)
+
+static inline void pte_unmap(pte_t *pte) { }

  /* to find an entry in a kernel page-table-directory */
  /* This now only contains the vmalloc pages */


Christophe

>   
>   /* to find an entry in a kernel page-table-directory */
>   /* This now only contains the vmalloc pages */
> diff --git a/arch/powerpc/include/asm/nohash/64/pgtable.h b/arch/powerpc/include/asm/nohash/64/pgtable.h
> index e77ed9761632..103071afab3d 100644
> --- a/arch/powerpc/include/asm/nohash/64/pgtable.h
> +++ b/arch/powerpc/include/asm/nohash/64/pgtable.h
> @@ -205,7 +205,7 @@ static inline void pgd_set(pgd_t *pgdp, unsigned long val)
>     (((pte_t *) pmd_page_vaddr(*(dir))) + (((addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)))
>   
>   #define pte_offset_map(dir,addr)	pte_offset_kernel((dir), (addr))
> -#define pte_unmap(pte)			do { } while(0)
> +#define pte_unmap(pte)			(void)(pte)
>   
>   /* to find an entry in a kernel page-table-directory */
>   /* This now only contains the vmalloc pages */
>