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From: "Huang, Ying" <ying.huang@intel.com>
To: liqiang <liqiang64@huawei.com>
Cc: <akpm@linux-foundation.org>,  <paulmck@linux.vnet.ibm.com>,
  <neilb@suse.de>,  <chuck.lever@oracle.com>,
  <linux-kernel@vger.kernel.org>
Subject: Re: [RESEND PATCH] llist: Make llist_del_first return only the
 first node
In-Reply-To: <20240218065750.1241-1-liqiang64@huawei.com> (liqiang's message
	of "Sun, 18 Feb 2024 14:57:50 +0800")
References: <20240218065750.1241-1-liqiang64@huawei.com>
Date: Sun, 18 Feb 2024 15:43:30 +0800
Message-ID: <875xymtdy5.fsf@yhuang6-desk2.ccr.corp.intel.com>
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liqiang <liqiang64@huawei.com> writes:

> Set the next of the returned node of llist_del_first
> to NULL, which can prevent subsequent nodes in llist
> from being exposed, and is more consistent with the
> logic of this interface.
>
> Signed-off-by: liqiang <liqiang64@huawei.com>
> ---
>  lib/llist.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/lib/llist.c b/lib/llist.c
> index f21d0cf..c33fff5 100644
> --- a/lib/llist.c
> +++ b/lib/llist.c
> @@ -61,6 +61,7 @@ struct llist_node *llist_del_first(struct llist_head *head)
>  		next = READ_ONCE(entry->next);
>  	} while (!try_cmpxchg(&head->first, &entry, next));
>  
> +	entry->next = NULL;
>  	return entry;
>  }
>  EXPORT_SYMBOL_GPL(llist_del_first);

This isn't needed for functionality correctness.  Many users of llist
ask for performance.  So, it may be better to let the users to decide
whether to set entry->next to NULL.

--
Best Regards,
Huang, Ying