linux-kernel - Re: [PATCH 2/3] mm/swap: simplify enable_swap_slots

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Date:   Fri, 1 May 2020 14:59:57 -0700
From:   Tim Chen <tim.c.chen@...ux.intel.com>
To:     Zhen Lei <thunder.leizhen@...wei.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-mm <linux-mm@...ck.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/3] mm/swap: simplify enable_swap_slots_cache()



On 4/29/20 11:11 PM, Zhen Lei wrote:
> Whether swap_slot_cache_initialized is true or false,
> __reenable_swap_slots_cache() is always called. To make this meaning
> clear, leave only one call to __reenable_swap_slots_cache(). This also
> make it clearer what extra needs be done when swap_slot_cache_initialized
> is false.
> 
> No functional change.
> 
> Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>

Acked-by: Tim Chen <tim.c.chen@...ux.intel.com>

> ---
>  mm/swap_slots.c | 22 ++++++++++------------
>  1 file changed, 10 insertions(+), 12 deletions(-)
> 
> diff --git a/mm/swap_slots.c b/mm/swap_slots.c
> index 01609b5f0c55..b40394473a3c 100644
> --- a/mm/swap_slots.c
> +++ b/mm/swap_slots.c
> @@ -240,21 +240,19 @@ static int free_slot_cache(unsigned int cpu)
>  
>  int enable_swap_slots_cache(void)
>  {
> -	int ret = 0;
> -
>  	mutex_lock(&swap_slots_cache_enable_mutex);
> -	if (swap_slot_cache_initialized) {
> -		__reenable_swap_slots_cache();
> -		goto out_unlock;
> -	}
> +	if (!swap_slot_cache_initialized) {
> +		int ret;
>  
> -	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "swap_slots_cache",
> -				alloc_swap_slot_cache, free_slot_cache);
> -	if (WARN_ONCE(ret < 0, "Cache allocation failed (%s), operating "
> -			       "without swap slots cache.\n", __func__))
> -		goto out_unlock;
> +		ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "swap_slots_cache",
> +					alloc_swap_slot_cache, free_slot_cache);
> +		if (WARN_ONCE(ret < 0, "Cache allocation failed (%s), operating "
> +				       "without swap slots cache.\n", __func__))
> +			goto out_unlock;
> +
> +		swap_slot_cache_initialized = true;
> +	}
>  
> -	swap_slot_cache_initialized = true;
>  	__reenable_swap_slots_cache();
>  out_unlock:
>  	mutex_unlock(&swap_slots_cache_enable_mutex);
>