Re: [PATCH] mm/sparse: remove a check that compare if unsigned variable is negative
From: Pavel Tatashin
Date: Sat Oct 13 2018 - 13:05:25 EST
This is incorrect: next_present_section_nr() returns "int" and -1 no
next section, this change would lead to infinite loop.
On Sat, Oct 13, 2018 at 12:16 PM Peng Hao <penghao122@xxxxxxxxxxx> wrote:
>
>
> From: Peng Hao <peng.hao2@xxxxxxxxxx>
>
> In all use locations for for_each_present_section_nr, variable
> section_nr is unsigned. It is unnecessary to test if it is negative.
>
> Signed-off-by: Peng Hao <peng.hao2@xxxxxxxxxx>
> ---
> mm/sparse.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/mm/sparse.c b/mm/sparse.c
> index 10b07ee..a6f9f22 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -196,8 +196,7 @@ static inline int next_present_section_nr(int section_nr)
> }
> #define for_each_present_section_nr(start, section_nr) \
> for (section_nr = next_present_section_nr(start-1); \
> - ((section_nr >= 0) && \
> - (section_nr <= __highest_present_section_nr)); \
> + section_nr <= __highest_present_section_nr; \
> section_nr = next_present_section_nr(section_nr))
>
> static inline unsigned long first_present_section_nr(void)
> --
> 1.8.3.1
>
>