linux-kernel - Re: [PATCH] wireguard: allowedips: Use kfree_rcu() instead of call

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Message-ID: <CANn89iJs+Y7Ge2sbAOQSsuE6O1GbxuHbNrFxBO0fq1C3HOfxPA@mail.gmail.com>
Date: Sun, 5 Oct 2025 06:04:31 -0700
From: Eric Dumazet <edumazet@...gle.com>
To: Fushuai Wang <wangfushuai@...du.com>
Cc: Jason@...c4.com, andrew+netdev@...n.ch, davem@...emloft.net, 
	kuba@...nel.org, pabeni@...hat.com, wireguard@...ts.zx2c4.com, 
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] wireguard: allowedips: Use kfree_rcu() instead of call_rcu()

On Sun, Oct 5, 2025 at 5:26 AM Fushuai Wang <wangfushuai@...du.com> wrote:
>
> Replace call_rcu() + kmem_cache_free() with kfree_rcu() to simplify
> the code and reduce function size.
>
> Signed-off-by: Fushuai Wang <wangfushuai@...du.com>

Hmm... have you compiled this patch ?

I think  all compilers would complain loudly.

> ---
>  drivers/net/wireguard/allowedips.c | 9 ++-------
>  1 file changed, 2 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/net/wireguard/allowedips.c b/drivers/net/wireguard/allowedips.c
> index 09f7fcd7da78..506f7cf0d7cf 100644
> --- a/drivers/net/wireguard/allowedips.c
> +++ b/drivers/net/wireguard/allowedips.c
> @@ -48,11 +48,6 @@ static void push_rcu(struct allowedips_node **stack,
>         }
>  }
>
> -static void node_free_rcu(struct rcu_head *rcu)
> -{
> -       kmem_cache_free(node_cache, container_of(rcu, struct allowedips_node, rcu));
> -}
> -
>  static void root_free_rcu(struct rcu_head *rcu)
>  {
>         struct allowedips_node *node, *stack[MAX_ALLOWEDIPS_DEPTH] = {
> @@ -271,13 +266,13 @@ static void remove_node(struct allowedips_node *node, struct mutex *lock)
>         if (free_parent)
>                 child = rcu_dereference_protected(parent->bit[!(node->parent_bit_packed & 1)],
>                                                   lockdep_is_held(lock));
> -       call_rcu(&node->rcu, node_free_rcu);
> +       kfree_rcu(&node, rcu);

kfree_rcu(node, rcu);

>         if (!free_parent)
>                 return;
>         if (child)
>                 child->parent_bit_packed = parent->parent_bit_packed;
>         *(struct allowedips_node **)(parent->parent_bit_packed & ~3UL) = child;
> -       call_rcu(&parent->rcu, node_free_rcu);
> +       kfree_rcu(&parent, rcu);

kfree_rcu(parent, rcu);

>  }
>
>  static int remove(struct allowedips_node __rcu **trie, u8 bits, const u8 *key,
> --
> 2.36.1
>