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From:   Vitaly Wool <vitaly.wool@konsulko.com>
Date:   Wed, 2 Mar 2022 09:40:49 +0100
Message-ID: <CAM4kBBK_a_2d5f7=OF2euGacnGoKM-8oVu0uQ86cTMvuAtPuPA@mail.gmail.com>
Subject: Re: [PATCH 9/9] mm/z3fold: remove unneeded return value of z3fold_compact_page()
To:     Miaohe Lin <linmiaohe@huawei.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Linux-MM <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>
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On Sat, Feb 19, 2022 at 10:26 AM Miaohe Lin <linmiaohe@huawei.com> wrote:
>
> Remove the unneeded return value of z3fold_compact_page() as it's
> never checked.

It was a sort of hook for gathering extended compaction statistics in
future. Do you really gain a lot by removing this?

~Vitaly

> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---
>  mm/z3fold.c | 14 +++++---------
>  1 file changed, 5 insertions(+), 9 deletions(-)
>
> diff --git a/mm/z3fold.c b/mm/z3fold.c
> index 83b5a3514427..db41b4227ec7 100644
> --- a/mm/z3fold.c
> +++ b/mm/z3fold.c
> @@ -746,18 +746,18 @@ static struct z3fold_header *compact_single_buddy(struct z3fold_header *zhdr)
>
>  #define BIG_CHUNK_GAP  3
>  /* Has to be called with lock held */
> -static int z3fold_compact_page(struct z3fold_header *zhdr)
> +static void z3fold_compact_page(struct z3fold_header *zhdr)
>  {
>         struct page *page = virt_to_page(zhdr);
>
>         if (test_bit(MIDDLE_CHUNK_MAPPED, &page->private))
> -               return 0; /* can't move middle chunk, it's used */
> +               return; /* can't move middle chunk, it's used */
>
>         if (unlikely(PageIsolated(page)))
> -               return 0;
> +               return;
>
>         if (zhdr->middle_chunks == 0)
> -               return 0; /* nothing to compact */
> +               return; /* nothing to compact */
>
>         if (zhdr->first_chunks == 0 && zhdr->last_chunks == 0) {
>                 /* move to the beginning */
> @@ -766,7 +766,7 @@ static int z3fold_compact_page(struct z3fold_header *zhdr)
>                 zhdr->middle_chunks = 0;
>                 zhdr->start_middle = 0;
>                 zhdr->first_num++;
> -               return 1;
> +               return;
>         }
>
>         /*
> @@ -778,7 +778,6 @@ static int z3fold_compact_page(struct z3fold_header *zhdr)
>                         BIG_CHUNK_GAP) {
>                 mchunk_memmove(zhdr, zhdr->first_chunks + ZHDR_CHUNKS);
>                 zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
> -               return 1;
>         } else if (zhdr->last_chunks != 0 && zhdr->first_chunks == 0 &&
>                    TOTAL_CHUNKS - (zhdr->last_chunks + zhdr->start_middle
>                                         + zhdr->middle_chunks) >=
> @@ -787,10 +786,7 @@ static int z3fold_compact_page(struct z3fold_header *zhdr)
>                         zhdr->middle_chunks;
>                 mchunk_memmove(zhdr, new_start);
>                 zhdr->start_middle = new_start;
> -               return 1;
>         }
> -
> -       return 0;
>  }
>
>  static void do_compact_page(struct z3fold_header *zhdr, bool locked)
> --
> 2.23.0
>