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From: Huacai Chen <chenhuacai@kernel.org>
Date: Sun, 10 Mar 2024 09:14:24 +0800
Message-ID: <CAAhV-H6O02es7ZsDRjWfO=9hz8owa1SWZXkyZ=p3BO28D+ix6A@mail.gmail.com>
Subject: Re: [PATCH] loongarch/pgtable.h: move {dmw,tlb}_virt_to_page() to page.h
To: Max Kellermann <max.kellermann@ionos.com>
Cc: kernel@xen0n.name, lienze@kylinos.cn, yangtiezhu@loongson.cn, 
	tglx@linutronix.de, arnd@arndb.de, loongarch@lists.linux.dev, 
	linux-kernel@vger.kernel.org
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Hi, Max,

Could you please share what kind of configuration will cause a build error?

Huacai

On Fri, Mar 8, 2024 at 3:46=E2=80=AFPM Max Kellermann <max.kellermann@ionos=
com> wrote:
>
> These functions are implemented in pgtable.c, and they are needed only
> by the virt_to_pfn() macro in page.h.  Having the prototypes in
> pgtable.h causes a circular dependency between page.h and pgtable.h,
> because page.h's virt_to_pfn() needs pgtable.h for these two
> functions, and pgtable.h needs various definitions from page.h
> (e.g. pte_t and pgt_t).
>
> I suggest avoiding this circular dependency by moving the function
> prototypes to page.h, even though that is slightly incorrect, because
> they are not implemented in page.c but pgtable.c, but it's the
> simplest possible solution to this problem and the functions not used
> anywhere else.
>
> Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
> ---
>  arch/loongarch/include/asm/page.h    | 3 +++
>  arch/loongarch/include/asm/pgtable.h | 3 ---
>  2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/loongarch/include/asm/page.h b/arch/loongarch/include/a=
sm/page.h
> index afb6fa16b826..44027060c54a 100644
> --- a/arch/loongarch/include/asm/page.h
> +++ b/arch/loongarch/include/asm/page.h
> @@ -75,6 +75,9 @@ typedef struct { unsigned long pgprot; } pgprot_t;
>  #define pfn_to_kaddr(pfn)      __va((pfn) << PAGE_SHIFT)
>  #define sym_to_pfn(x)          __phys_to_pfn(__pa_symbol(x))
>
> +struct page *dmw_virt_to_page(unsigned long kaddr);
> +struct page *tlb_virt_to_page(unsigned long kaddr);
> +
>  #define virt_to_pfn(kaddr)     PFN_DOWN(PHYSADDR(kaddr))
>
>  #define virt_to_page(kaddr)                                             =
               \
> diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/includ=
e/asm/pgtable.h
> index 8b5df1bbf9e9..af3acdf3481a 100644
> --- a/arch/loongarch/include/asm/pgtable.h
> +++ b/arch/loongarch/include/asm/pgtable.h
> @@ -363,9 +363,6 @@ static inline void pte_clear(struct mm_struct *mm, un=
signed long addr, pte_t *pt
>  extern pgd_t swapper_pg_dir[];
>  extern pgd_t invalid_pg_dir[];
>
> -struct page *dmw_virt_to_page(unsigned long kaddr);
> -struct page *tlb_virt_to_page(unsigned long kaddr);
> -
>  /*
>   * The following only work if pte_present() is true.
>   * Undefined behaviour if not..
> --
> 2.39.2
>
>