linux-kernel - Re: [PATCH v8 3/8] mm: zswap: Rename zswap_pool_get() to zswap_pool

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Message-ID: <2c9d403f-188b-4f15-93d7-36224ef31329@linux.dev>
Date: Sat, 28 Sep 2024 13:43:41 +0800
From: Chengming Zhou <chengming.zhou@...ux.dev>
To: Kanchana P Sridhar <kanchana.p.sridhar@...el.com>,
 linux-kernel@...r.kernel.org, linux-mm@...ck.org, hannes@...xchg.org,
 yosryahmed@...gle.com, nphamcs@...il.com, usamaarif642@...il.com,
 shakeel.butt@...ux.dev, ryan.roberts@....com, ying.huang@...el.com,
 21cnbao@...il.com, akpm@...ux-foundation.org
Cc: nanhai.zou@...el.com, wajdi.k.feghali@...el.com, vinodh.gopal@...el.com
Subject: Re: [PATCH v8 3/8] mm: zswap: Rename zswap_pool_get() to
 zswap_pool_tryget().

On 2024/9/28 10:16, Kanchana P Sridhar wrote:
> Modify the name of the existing zswap_pool_get() to zswap_pool_tryget()
> to be representative of the call it makes to percpu_ref_tryget().
> A subsequent patch will introduce a new zswap_pool_get() that calls
> percpu_ref_get().
> 
> The intent behind this change is for higher level zswap API such as
> zswap_store() to call zswap_pool_tryget() to check upfront if the pool's
> refcount is "0" (which means it could be getting destroyed) and to handle
> this as an error condition. zswap_store() would proceed only if
> zswap_pool_tryget() returns success, and any additional pool refcounts that
> need to be obtained for compressing sub-pages in a large folio could simply
> call zswap_pool_get().
> 
> Signed-off-by: Kanchana P Sridhar <kanchana.p.sridhar@...el.com>

Reviewed-by: Chengming Zhou <chengming.zhou@...ux.dev>

> ---
>   mm/zswap.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/zswap.c b/mm/zswap.c
> index fd7a8c14457a..0f281e50a034 100644
> --- a/mm/zswap.c
> +++ b/mm/zswap.c
> @@ -403,7 +403,7 @@ static void __zswap_pool_empty(struct percpu_ref *ref)
>   	spin_unlock_bh(&zswap_pools_lock);
>   }
>   
> -static int __must_check zswap_pool_get(struct zswap_pool *pool)
> +static int __must_check zswap_pool_tryget(struct zswap_pool *pool)
>   {
>   	if (!pool)
>   		return 0;
> @@ -441,7 +441,7 @@ static struct zswap_pool *zswap_pool_current_get(void)
>   	rcu_read_lock();
>   
>   	pool = __zswap_pool_current();
> -	if (!zswap_pool_get(pool))
> +	if (!zswap_pool_tryget(pool))
>   		pool = NULL;
>   
>   	rcu_read_unlock();
> @@ -462,7 +462,7 @@ static struct zswap_pool *zswap_pool_find_get(char *type, char *compressor)
>   		if (strcmp(zpool_get_type(pool->zpool), type))
>   			continue;
>   		/* if we can't get it, it's about to be destroyed */
> -		if (!zswap_pool_get(pool))
> +		if (!zswap_pool_tryget(pool))
>   			continue;
>   		return pool;
>   	}