On 4/29/20 11:11 PM, Zhen Lei wrote:
> Because enable_swap_slots_cache can only become true in
> enable_swap_slots_cache(), and depends on swap_slot_cache_initialized is
> true before. That means, when enable_swap_slots_cache is true,
> swap_slot_cache_initialized is true also.
>
> So the condition:
> "swap_slot_cache_enabled && swap_slot_cache_initialized"
> can be reduced to "swap_slot_cache_enabled"
>
> And in mathematics:
> "!swap_slot_cache_enabled || !swap_slot_cache_initialized"
> is equal to "!(swap_slot_cache_enabled && swap_slot_cache_initialized)"
>
> So no functional change.
>
> Signed-off-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
> ---
> mm/swap_slots.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/mm/swap_slots.c b/mm/swap_slots.c
> index b40394473a3c..3e6453573a89 100644
> --- a/mm/swap_slots.c
> +++ b/mm/swap_slots.c
> @@ -46,8 +46,7 @@ static void __drain_swap_slots_cache(unsigned int type);
> static void deactivate_swap_slots_cache(void);
> static void reactivate_swap_slots_cache(void);
>
> -#define use_swap_slot_cache (swap_slot_cache_active && \
> - swap_slot_cache_enabled && swap_slot_cache_initialized)
> +#define use_swap_slot_cache (swap_slot_cache_active && swap_slot_cache_enabled)
Yes, swap_slot_cache_enabled does imply swap_slot_cache_initialized
in current code. So checking swap_slot_cache_enabled is
enough here.
> #define SLOTS_CACHE 0x1
> #define SLOTS_CACHE_RET 0x2
>
> @@ -94,7 +93,7 @@ static bool check_cache_active(void)
> {
> long pages;
>
> - if (!swap_slot_cache_enabled || !swap_slot_cache_initialized)
> + if (!swap_slot_cache_enabled)
This simplification is okay. !swap_slot_cache_initialize implies !swap_slot_cache_enabled.
So only !swap_slot_cache_enabled needs to be checked.
> return false;
>
> pages = get_nr_swap_pages();
>
Acked-by: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>
