linux-kernel - Re: [PATCH 5/5] mm: migrate: Remove redundant goto labels

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Message-ID: <CAHbLzko_spW=SPnP3jgQWCNzY=7xn7JDCFfFtY5_9yRfCApLTA@mail.gmail.com>
Date:   Fri, 6 Aug 2021 10:17:46 -0700
From:   Yang Shi <shy828301@...il.com>
To:     Baolin Wang <baolin.wang@...ux.alibaba.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Linux MM <linux-mm@...ck.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 5/5] mm: migrate: Remove redundant goto labels

On Thu, Aug 5, 2021 at 8:19 PM Baolin Wang
<baolin.wang@...ux.alibaba.com> wrote:
>
> Hi Yang,
>
> > On Thu, Aug 5, 2021 at 8:06 AM Baolin Wang
> > <baolin.wang@...ux.alibaba.com> wrote:
> >>
> >> Remove redundant goto labels to simplify the code.
> >
> > TBH I don't see too much benefit. The "goto" makes the functions have
> > a single exit point.
>
> Yes, I agree that the 'goto' statement can make things easier when a
> function exits from multiple locations and some common work such as
> cleanup has to be done, as well as introducing complexity to reading the
> code. So per the coding style documentation, "If there is no cleanup
> needed then just return directly", which can make code more readable I
> think :)
>
> But I have no strong opinion on this, I can drop this patch if you still
> think this is unnecessary. Thanks for your review and comments.

Thanks, IMHO I'd like to drop it for now.

>
> >> Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
> >> ---
> >>   mm/migrate.c | 8 +++-----
> >>   1 file changed, 3 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/mm/migrate.c b/mm/migrate.c
> >> index 0ab364f..ed74fda 100644
> >> --- a/mm/migrate.c
> >> +++ b/mm/migrate.c
> >> @@ -911,9 +911,8 @@ static int move_to_new_page(struct page *newpage, struct page *page,
> >>                   */
> >>                  VM_BUG_ON_PAGE(!PageIsolated(page), page);
> >>                  if (!PageMovable(page)) {
> >> -                       rc = MIGRATEPAGE_SUCCESS;
> >>                          __ClearPageIsolated(page);
> >> -                       goto out;
> >> +                       return MIGRATEPAGE_SUCCESS;
> >>                  }
> >>
> >>                  rc = mapping->a_ops->migratepage(mapping, newpage,
> >> @@ -949,7 +948,7 @@ static int move_to_new_page(struct page *newpage, struct page *page,
> >>                          flush_dcache_page(newpage);
> >>
> >>          }
> >> -out:
> >> +
> >>          return rc;
> >>   }
> >>
> >> @@ -2095,11 +2094,10 @@ static struct page *alloc_misplaced_dst_page_thp(struct page *page,
> >>          newpage = alloc_pages_node(nid, (GFP_TRANSHUGE_LIGHT | __GFP_THISNODE),
> >>                                     HPAGE_PMD_ORDER);
> >>          if (!newpage)
> >> -               goto out;
> >> +               return NULL;
> >>
> >>          prep_transhuge_page(newpage);
> >>
> >> -out:
> >>          return newpage;
> >>   }
> >>
> >> --
> >> 1.8.3.1
> >>
> >>