linux-kernel - Re: [PATCH] firewire: core: utilize kref to maintain fw

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Message-ID: <20240801232938.GA58901@workstation.local>
Date: Fri, 2 Aug 2024 08:29:38 +0900
From: Takashi Sakamoto <o-takashi@...amocchi.jp>
To: linux1394-devel@...ts.sourceforge.net
Cc: linux-kernel@...r.kernel.org
Subject: Re: [PATCH] firewire: core: utilize kref to maintain fw_node with
 reference counting

On Thu, Aug 01, 2024 at 11:26:29AM +0900, Takashi Sakamoto wrote:
> Current implementation directly uses refcount_t to maintain the life time
> of fw_node, while kref is available for the same purpose.
> 
> This commit replaces the implementation with kref.
> 
> Signed-off-by: Takashi Sakamoto <o-takashi@...amocchi.jp>
> ---
>  drivers/firewire/core-topology.c |  2 +-
>  drivers/firewire/core.h          | 15 +++++++++++----
>  2 files changed, 12 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/firewire/core-topology.c b/drivers/firewire/core-topology.c
> index b4e637aa6932..46e6eb287d24 100644
> --- a/drivers/firewire/core-topology.c
> +++ b/drivers/firewire/core-topology.c
> @@ -39,7 +39,7 @@ static struct fw_node *fw_node_create(u32 sid, int port_count, int color)
>  	node->initiated_reset = phy_packet_self_id_zero_get_initiated_reset(sid);
>  	node->port_count = port_count;
>  
> -	refcount_set(&node->ref_count, 1);
> +	kref_init(&node->kref);
>  	INIT_LIST_HEAD(&node->link);
>  
>  	return node;
> diff --git a/drivers/firewire/core.h b/drivers/firewire/core.h
> index 7c36d2628e37..189e15e6ba82 100644
> --- a/drivers/firewire/core.h
> +++ b/drivers/firewire/core.h
> @@ -183,7 +183,8 @@ struct fw_node {
>  			 * local node to this node. */
>  	u8 max_depth:4;	/* Maximum depth to any leaf node */
>  	u8 max_hops:4;	/* Max hops in this sub tree */
> -	refcount_t ref_count;
> +
> +	struct kref kref;
>  
>  	/* For serializing node topology into a list. */
>  	struct list_head link;
> @@ -196,15 +197,21 @@ struct fw_node {
>  
>  static inline struct fw_node *fw_node_get(struct fw_node *node)
>  {
> -	refcount_inc(&node->ref_count);
> +	kref_get(&node->kref);
>  
>  	return node;
>  }
>  
> +static void release_node(struct kref *kref)
> +{
> +	struct fw_node *node = container_of(kref, struct fw_node, kref);
> +
> +	kfree(node);
> +}
> +
>  static inline void fw_node_put(struct fw_node *node)
>  {
> -	if (refcount_dec_and_test(&node->ref_count))
> -		kfree(node);
> +	kref_put(&node->kref, release_node);
>  }
>  
>  void fw_core_handle_bus_reset(struct fw_card *card, int node_id,

Applied to for-next branch.


Regards

Takashi Sakamoto