netdev - Re: [PATCH net-next 12/14] net: sched: act_mirred: remove dependency on rtnl lock

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Date:   Tue, 7 Aug 2018 18:36:30 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     Vlad Buslov <vladbu@...lanox.com>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, jhs@...atatu.com,
        xiyou.wangcong@...il.com, pablo@...filter.org,
        kadlec@...ckhole.kfki.hu, fw@...len.de, ast@...nel.org,
        daniel@...earbox.net, edumazet@...gle.com, keescook@...omium.org,
        marcelo.leitner@...il.com
Subject: Re: [PATCH net-next 12/14] net: sched: act_mirred: remove dependency
 on rtnl lock

Mon, Aug 06, 2018 at 08:54:23AM CEST, vladbu@...lanox.com wrote:

[...]

>diff --git a/include/net/tc_act/tc_tunnel_key.h b/include/net/tc_act/tc_tunnel_key.h
>index 46b8c7f1c8d5..e6e475d788c6 100644
>--- a/include/net/tc_act/tc_tunnel_key.h
>+++ b/include/net/tc_act/tc_tunnel_key.h
>@@ -30,26 +30,47 @@ struct tcf_tunnel_key {
> 
> static inline bool is_tcf_tunnel_set(const struct tc_action *a)
> {
>+	bool ret = false;
> #ifdef CONFIG_NET_CLS_ACT
> 	struct tcf_tunnel_key *t = to_tunnel_key(a);
>-	struct tcf_tunnel_key_params *params = rtnl_dereference(t->params);
>+	struct tcf_tunnel_key_params *params;
> 
>+	rcu_read_lock();
>+	params = rcu_dereference(t->params);
> 	if (a->ops && a->ops->type == TCA_ACT_TUNNEL_KEY)
>-		return params->tcft_action == TCA_TUNNEL_KEY_ACT_SET;
>+		ret = params->tcft_action == TCA_TUNNEL_KEY_ACT_SET;
>+	rcu_read_unlock();
> #endif
>-	return false;
>+	return ret;
> }
> 
> static inline bool is_tcf_tunnel_release(const struct tc_action *a)

Why are these tunnel things in a mirred patch?


[...]


> static struct net_device *tcf_mirred_get_dev(const struct tc_action *a)
> {
> 	struct tcf_mirred *m = to_mirred(a);
>+	struct net_device *dev;
>+
>+	rcu_read_lock();
>+	dev = rcu_dereference(m->tcfm_dev);
>+	if (dev)
>+		dev_hold(dev);
>+	rcu_read_unlock();
> 
>-	return rtnl_dereference(m->tcfm_dev);
>+	return dev;
> }
> 
> static int tcf_mirred_delete(struct net *net, u32 index)
>diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
>index e8b0bbd0883f..0cce0eadc28b 100644
>--- a/net/sched/cls_api.c
>+++ b/net/sched/cls_api.c
>@@ -2167,6 +2167,7 @@ static int tc_exts_setup_cb_egdev_call(struct tcf_exts *exts,
> 		if (!dev)
> 			continue;
> 		ret = tc_setup_cb_egdev_call(dev, type, type_data, err_stop);
>+		dev_put(dev);

This looks really odd. a->ops->put_dev is needed.


> 		if (ret < 0)
> 			return ret;
> 		ok_count += ret;
>-- 
>2.7.5
>