linux-kernel - Re: [PATCH 05/20] mm: zswap: clean up zswap_entry

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Message-ID: <Zbiqmi0KMo0zTJ-p@google.com>
Date: Tue, 30 Jan 2024 07:51:54 +0000
From: Yosry Ahmed <yosryahmed@...gle.com>
To: Johannes Weiner <hannes@...xchg.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>, Nhat Pham <nphamcs@...il.com>, 
	Chengming Zhou <zhouchengming@...edance.com>, linux-mm@...ck.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 05/20] mm: zswap: clean up zswap_entry_put()

On Mon, Jan 29, 2024 at 08:36:41PM -0500, Johannes Weiner wrote:
> Remove stale comment and unnecessary local variable.
> 
> Signed-off-by: Johannes Weiner <hannes@...xchg.org>
> ---
>  mm/zswap.c | 10 +++-------
>  1 file changed, 3 insertions(+), 7 deletions(-)
> 
> diff --git a/mm/zswap.c b/mm/zswap.c
> index 0c6adaf2fdb6..7a7e8da2b4f8 100644
> --- a/mm/zswap.c
> +++ b/mm/zswap.c
> @@ -546,15 +546,11 @@ static void zswap_entry_get(struct zswap_entry *entry)
>  	entry->refcount++;
>  }
>  
> -/* caller must hold the tree lock
> -* remove from the tree and free it, if nobody reference the entry
> -*/
> +/* caller must hold the tree lock */

We should replace all those "caller must hold the tree lock" comments
with lockdep_assert_held() or assert_spin_locked() or something.

I can send follow up patches on top if you don't want to resend this
series.

>  static void zswap_entry_put(struct zswap_entry *entry)
>  {
> -	int refcount = --entry->refcount;
> -
> -	WARN_ON_ONCE(refcount < 0);
> -	if (refcount == 0) {
> +	WARN_ON_ONCE(!entry->refcount);
> +	if (--entry->refcount == 0) {
>  		WARN_ON_ONCE(!RB_EMPTY_NODE(&entry->rbnode));
>  		zswap_entry_free(entry);
>  	}
> -- 
> 2.43.0
>