On Tue, Jun 1, 2021 at 4:40 PM David Hildenbrand <da...@redhat.com> wrote:
>
> On 01.06.21 10:37, Dong Aisheng wrote:
> > On Tue, Jun 1, 2021 at 4:22 PM David Hildenbrand <da...@redhat.com> wrote:
> >>
> >> On 31.05.21 11:19, Dong Aisheng wrote:
> >>> In order to distinguish the struct mem_section for a better code
> >>> readability and align with kernel doc [1] name below, change the
> >>> global mem section name to 'mem_sections' from 'mem_section'.
> >>>
> >>> [1] Documentation/vm/memory-model.rst
> >>> "The `mem_section` objects are arranged in a two-dimensional array
> >>> called `mem_sections`."
> >>>
> >>> Cc: Andrew Morton <a...@linux-foundation.org>
> >>> Cc: Dave Young <dyo...@redhat.com>
> >>> Cc: Baoquan He <b...@redhat.com>
> >>> Cc: Vivek Goyal <vgo...@redhat.com>
> >>> Cc: kexec@lists.infradead.org
> >>> Signed-off-by: Dong Aisheng <aisheng.d...@nxp.com>
> >>> ---
> >>> v1->v2:
> >>> * no changes
> >>> ---
> >>> include/linux/mmzone.h | 10 +++++-----
> >>> kernel/crash_core.c | 4 ++--
> >>> mm/sparse.c | 16 ++++++++--------
> >>> 3 files changed, 15 insertions(+), 15 deletions(-)
> >>>
> >>> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> >>> index a6bfde85ddb0..0ed61f32d898 100644
> >>> --- a/include/linux/mmzone.h
> >>> +++ b/include/linux/mmzone.h
> >>> @@ -1302,9 +1302,9 @@ struct mem_section {
> >>> #define SECTION_ROOT_MASK (SECTIONS_PER_ROOT - 1)
> >>>
> >>> #ifdef CONFIG_SPARSEMEM_EXTREME
> >>> -extern struct mem_section **mem_section;
> >>> +extern struct mem_section **mem_sections;
> >>> #else
> >>> -extern struct mem_section
> >>> mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
> >>> +extern struct mem_section
> >>> mem_sections[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
> >>> #endif
> >>>
> >>> static inline unsigned long *section_to_usemap(struct mem_section *ms)
> >>> @@ -1315,12 +1315,12 @@ static inline unsigned long
> >>> *section_to_usemap(struct mem_section *ms)
> >>> static inline struct mem_section *__nr_to_section(unsigned long nr)
> >>> {
> >>> #ifdef CONFIG_SPARSEMEM_EXTREME
> >>> - if (!mem_section)
> >>> + if (!mem_sections)
> >>> return NULL;
> >>> #endif
> >>> - if (!mem_section[SECTION_NR_TO_ROOT(nr)])
> >>> + if (!mem_sections[SECTION_NR_TO_ROOT(nr)])
> >>> return NULL;
> >>> - return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK];
> >>> + return &mem_sections[SECTION_NR_TO_ROOT(nr)][nr &
> >>> SECTION_ROOT_MASK];
> >>> }
> >>> extern unsigned long __section_nr(struct mem_section *ms);
> >>> extern size_t mem_section_usage_size(void);
> >>> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> >>> index 29cc15398ee4..fb1180d81b5a 100644
> >>> --- a/kernel/crash_core.c
> >>> +++ b/kernel/crash_core.c
> >>> @@ -414,8 +414,8 @@ static int __init crash_save_vmcoreinfo_init(void)
> >>> VMCOREINFO_SYMBOL(contig_page_data);
> >>> #endif
> >>> #ifdef CONFIG_SPARSEMEM
> >>> - VMCOREINFO_SYMBOL_ARRAY(mem_section);
> >>> - VMCOREINFO_LENGTH(mem_section, NR_SECTION_ROOTS);
> >>> + VMCOREINFO_SYMBOL_ARRAY(mem_sections);
> >>> + VMCOREINFO_LENGTH(mem_sections, NR_SECTION_ROOTS);
> >>> VMCOREINFO_STRUCT_SIZE(mem_section);
> >>> VMCOREINFO_OFFSET(mem_section, section_mem_map);
> >>> VMCOREINFO_NUMBER(MAX_PHYSMEM_BITS);
> >>> diff --git a/mm/sparse.c b/mm/sparse.c
> >>> index d02ee6bb7cbc..6412010478f7 100644
> >>> --- a/mm/sparse.c
> >>> +++ b/mm/sparse.c
> >>> @@ -24,12 +24,12 @@
> >>> * 1) mem_section - memory sections, mem_map's for valid memory
> >>> */
> >>> #ifdef CONFIG_SPARSEMEM_EXTREME
> >>> -struct mem_section **mem_section;
> >>> +struct mem_section **mem_sections;
> >>> #else
> >>> -struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
> >>> +struct mem_section mem_sections[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
> >>> ____cacheline_internodealigned_in_smp;
> >>> #endif
> >>> -EXPORT_SYMBOL(mem_section);
> >>> +EXPORT_SYMBOL(mem_sections);
> >>>
> >>> #ifdef NODE_NOT_IN_PAGE_FLAGS
> >>> /*
> >>> @@ -66,8 +66,8 @@ static void __init sparse_alloc_section_roots(void)
> >>>
> >>> size = sizeof(struct mem_section *) * NR_SECTION_ROOTS;
> >>> align = 1 << (INTERNODE_CACHE_SHIFT);
> >>> - mem_section = memblock_alloc(size, align);
> >>> - if (!mem_section)
> >>> + mem_sections = memblock_alloc(size, align);
> >>> + if (!mem_sections)
> >>> panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
> >>> __func__, size, align);
> >>> }
> >>> @@ -103,14 +103,14 @@ static int __meminit sparse_index_init(unsigned
> >>> long section_nr, int nid)
> >>> *
> >>> * The mem_hotplug_lock resolves the apparent race below.
> >>> */
> >>> - if (mem_section[root])
> >>> + if (mem_sections[root])
> >>> return 0;
> >>>
> >>> section = sparse_index_alloc(nid);
> >>> if (!section)
> >>> return -ENOMEM;
> >>>
> >>> - mem_section[root] = section;
> >>> + mem_sections[root] = section;
> >>>
> >>> return 0;
> >>> }
> >>> @@ -145,7 +145,7 @@ unsigned long __section_nr(struct mem_section *ms)
> >>> #else
> >>> unsigned long __section_nr(struct mem_section *ms)
> >>> {
> >>> - return (unsigned long)(ms - mem_section[0]);
> >>> + return (unsigned long)(ms - mem_sections[0]);
> >>> }
> >>> #endif
> >>>
> >>>
> >>
> >> I repeat: unnecessary code churn IMHO.
> >
> > Hi David,
> >
> > Thanks, i explained the reason during my last reply.
> > Andrew has already picked this patch to -mm tree.
>
> Just because it's in Andrews tree doesn't mean it will end up upstream. ;)
>
> Anyhow, no really strong opinion, it's simply unnecessary code churn
> that makes bisecting harder without real value IMHO.
In my practice, it helps improve the code reading efficiency with
scope and vim hotkey.
Before the change, I really feel mixed definition causes troubles in
reading code efficiently.
Anyway, that's my personal experience while others may have different options.
Thanks for the feedback.
Regards
Aisheng
>
> --
> Thanks,
>
> David / dhildenb
>
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