netdev - Re: [PATCH net-next v6 3/3] act_vlan: VLAN action rewrite to use RCU lock/unlock and update

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Date:   Mon, 6 Nov 2017 18:37:31 +0000
From:   Pieter Jansen van Vuuren <pieter.jansenvanvuuren@...ronome.com>
To:     Manish Kurup <kurup.manish@...il.com>
Cc:     jhs@...atatu.com, xiyou.wangcong@...il.com, jiri@...nulli.us,
        davem@...emloft.net, jakub.kicinski@...ronome.com,
        simon.horman@...ronome.com, john.hurley@...ronome.com,
        oss-drivers@...ronome.com, netdev@...r.kernel.org,
        aring@...atatu.com, mrv@...atatu.com,
        Manish Kurup <manish.kurup@...izon.com>
Subject: Re: [PATCH net-next v6 3/3] act_vlan: VLAN action rewrite to use
 RCU lock/unlock and update

On Fri,  3 Nov 2017 11:50:47 -0400
Manish Kurup <kurup.manish@...il.com> wrote:

> Using a spinlock in the VLAN action causes performance issues when the VLAN
> action is used on multiple cores. Rewrote the VLAN action to use RCU read
> locking for reads and updates instead.
> 
> Acked-by: Jamal Hadi Salim <jhs@...atatu.com>
> Acked-by: Jiri Pirko <jiri@...lanox.com>
> Signed-off-by: Manish Kurup <manish.kurup@...izon.com>
> ---
>  include/net/tc_act/tc_vlan.h | 46 +++++++++++++++++++++------
>  net/sched/act_vlan.c         | 75
> ++++++++++++++++++++++++++++++-------------- 2 files changed, 88
> insertions(+), 33 deletions(-)
...
>  
> +static void tcf_vlan_cleanup(struct tc_action *a, int bind)
> +{
> +	struct tcf_vlan *v = to_vlan(a);
> +	struct tcf_vlan_params *p;
> +
> +	p = rcu_dereference_protected(v->vlan_p, 1);
> +	kfree_rcu(p, rcu);
> +}
> +
>  static int tcf_vlan_dump(struct sk_buff *skb, struct tc_action *a,
>  			 int bind, int ref)
>  {
>  	unsigned char *b = skb_tail_pointer(skb);
>  	struct tcf_vlan *v = to_vlan(a);
> +	struct tcf_vlan_params *p = rtnl_dereference(v->vlan_p);
nack. This fails reverse xmas-tree.