Re: [PATCH v3 2/2] mm: remove odd HAVE_PTE_SPECIAL
From: Christophe LEROY <hidden>
Date: 2018-04-11 08:58:57
Also in:
linux-arm-kernel, linux-doc, linux-mm, linux-riscv, linux-sh, lkml, sparclinux
Le 11/04/2018 à 10:03, Laurent Dufour a écrit :
quoted hunk ↗ jump to hunk
Remove the additional define HAVE_PTE_SPECIAL and rely directly on CONFIG_ARCH_HAS_PTE_SPECIAL. There is no functional change introduced by this patch Signed-off-by: Laurent Dufour <redacted> --- mm/memory.c | 19 ++++++++----------- 1 file changed, 8 insertions(+), 11 deletions(-)diff --git a/mm/memory.c b/mm/memory.c index 96910c625daa..7f7dc7b2a341 100644 --- a/mm/memory.c +++ b/mm/memory.c@@ -817,17 +817,12 @@ static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr, * PFNMAP mappings in order to support COWable mappings. * */ -#ifdef CONFIG_ARCH_HAS_PTE_SPECIAL -# define HAVE_PTE_SPECIAL 1 -#else -# define HAVE_PTE_SPECIAL 0 -#endif struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr, pte_t pte, bool with_public_device) { unsigned long pfn = pte_pfn(pte); - if (HAVE_PTE_SPECIAL) { + if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL)) { if (likely(!pte_special(pte))) goto check_pfn; if (vma->vm_ops && vma->vm_ops->find_special_page)@@ -862,7 +857,7 @@ struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr, return NULL; } - /* !HAVE_PTE_SPECIAL case follows: */ + /* !CONFIG_ARCH_HAS_PTE_SPECIAL case follows: */ if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { if (vma->vm_flags & VM_MIXEDMAP) {@@ -881,7 +876,8 @@ struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr, if (is_zero_pfn(pfn)) return NULL; -check_pfn: + +check_pfn: __maybe_unused
See below
quoted hunk ↗ jump to hunk
if (unlikely(pfn > highest_memmap_pfn)) { print_bad_pte(vma, addr, pte, NULL); return NULL;@@ -891,7 +887,7 @@ struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr, * NOTE! We still have PageReserved() pages in the page tables. * eg. VDSO mappings can cause them to exist. */ -out: +out: __maybe_unused
Why do you need that change ? There is no reason for the compiler to complain. It would complain if the goto was within a #ifdef, but all the purpose of using IS_ENABLED() is to allow the compiler to properly handle all possible cases. That's all the force of IS_ENABLED() compared to ifdefs, and that the reason why they are plebicited, ref Linux Codying style for a detailed explanation. Christophe
quoted hunk ↗ jump to hunk
return pfn_to_page(pfn); }@@ -904,7 +900,7 @@ struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr, /* * There is no pmd_special() but there may be special pmds, e.g. * in a direct-access (dax) mapping, so let's just replicate the - * !HAVE_PTE_SPECIAL case from vm_normal_page() here. + * !CONFIG_ARCH_HAS_PTE_SPECIAL case from vm_normal_page() here. */ if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { if (vma->vm_flags & VM_MIXEDMAP) {@@ -1933,7 +1929,8 @@ static int __vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr, * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP * without pte special, it would there be refcounted as a normal page. */ - if (!HAVE_PTE_SPECIAL && !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) { + if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) && + !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) { struct page *page; /*