netdev - Re: [PATCH 6/7] get rid of tc_u

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Message-ID: <CAM_iQpWnydTkLYwmZq2gQPnNBTS6E0iNNgy1zsmYFcXkKJAnTw@mail.gmail.com>
Date:   Thu, 6 Sep 2018 21:18:47 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Al Viro <viro@...iv.linux.org.uk>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Jiri Pirko <jiri@...nulli.us>
Subject: Re: [PATCH 6/7] get rid of tc_u_common ->rcu

On Wed, Sep 5, 2018 at 12:04 PM Al Viro <viro@...iv.linux.org.uk> wrote:
>
> From: Al Viro <viro@...iv.linux.org.uk>
>
> unused
>
> Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
> ---
>  net/sched/cls_u32.c | 1 -
>  1 file changed, 1 deletion(-)
>
> diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c
> index 8a1a573487bd..be9240ae1417 100644
> --- a/net/sched/cls_u32.c
> +++ b/net/sched/cls_u32.c
> @@ -98,7 +98,6 @@ struct tc_u_common {
>         int                     refcnt;
>         struct idr              handle_idr;
>         struct hlist_node       hnode;
> -       struct rcu_head         rcu;
>  };

Just FYI:

This was added when RCU was introduced to u32 fast path,
it looks like on fast path we never touch tc_u_common, we
only use tp->root, all the rest are slow paths with RTNL lock,
so it is probably fine to just remove it rather than converting
that kfree() to kfree_rcu().