Re: [PATCH] mm, compaction: using uninitialized_var insteads setting 'flags' to 0 directly.

From: Vlastimil Babka
Date: Tue Sep 30 2014 - 03:27:30 EST


On 09/29/2014 05:30 AM, Xiubo Li wrote:
> Setting 'flags' to zero will be certainly a misleading way to avoid
> warning of 'flags' may be used uninitialized. uninitialized_var is
> a correct way because the warning is a false possitive.

Agree.

> Signed-off-by: Xiubo Li <Li.Xiubo@xxxxxxxxxxxxx>

Acked-by: Vlastimil Babka <vbabka@xxxxxxx>

> ---
> mm/compaction.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/mm/compaction.c b/mm/compaction.c
> index 92075d5..59a116d 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -344,7 +344,7 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
> {
> int nr_scanned = 0, total_isolated = 0;
> struct page *cursor, *valid_page = NULL;
> - unsigned long flags = 0;
> + unsigned long uninitialized_var(flags);
> bool locked = false;
> unsigned long blockpfn = *start_pfn;
>
> @@ -573,7 +573,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
> unsigned long nr_scanned = 0, nr_isolated = 0;
> struct list_head *migratelist = &cc->migratepages;
> struct lruvec *lruvec;
> - unsigned long flags = 0;
> + unsigned long uninitialized_var(flags);
> bool locked = false;
> struct page *page = NULL, *valid_page = NULL;
>
>

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