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

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Message-ID: <98937827-89ec-2a3b-b389-da28f8493cb1@linux.alibaba.com>
Date:   Fri, 6 Aug 2021 11:20:08 +0800
From:   Baolin Wang <baolin.wang@...ux.alibaba.com>
To:     Yang Shi <shy828301@...il.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

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.

>> 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
>>
>>