Subject: Re: [Patch net-next] act_mirred: use tcfm_dev in tcf_mirred_get_dev()

From: Jiri Pirko <[email-masked]>
Date: Fri, 1 Dec 2017 18:56:19 +0100

Thu, Nov 30, 2017 at 11:53:32PM CET, [email-masked] wrote:
>tcfm_dev always points to the correct netdev and we already
>hold a refcnt, so no need to use ifindex to lookup again.
>
>If we would support moving target netdev across netns, using
>pointer would be better than ifindex.
>
>Cc: Jiri Pirko <[email-masked]>
>Cc: Jamal Hadi Salim <[email-masked]>
>Signed-off-by: Cong Wang <[email-masked]>
>---
> include/net/tc_act/tc_mirred.h | 1 -
> net/sched/act_mirred.c         | 3 +--
> 2 files changed, 1 insertion(+), 3 deletions(-)
>
>diff --git a/include/net/tc_act/tc_mirred.h b/include/net/tc_act/tc_mirred.h
>index 21d253c9a8c6..b2dbbfaefd22 100644
>--- a/include/net/tc_act/tc_mirred.h
>+++ b/include/net/tc_act/tc_mirred.h
>@@ -11,7 +11,6 @@ struct tcf_mirred {
> 	int			tcfm_ifindex;
> 	bool			tcfm_mac_header_xmit;
> 	struct net_device __rcu	*tcfm_dev;
>-	struct net		*net;
> 	struct list_head	tcfm_list;
> };
> #define to_mirred(a) ((struct tcf_mirred *)a)
>diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c
>index 8b3e59388480..fe6489f9c3cf 100644
>--- a/net/sched/act_mirred.c
>+++ b/net/sched/act_mirred.c
>@@ -140,7 +140,6 @@ static int tcf_mirred_init(struct net *net, struct nlattr *nla,
> 	m->tcfm_eaction = parm->eaction;
> 	if (dev != NULL) {
> 		m->tcfm_ifindex = parm->ifindex;
>-		m->net = net;

Isn't this here so user may specify a ifindex of netdev which is not yet
present on the system (not sure how much sense that would make though...)

> 		if (ret != ACT_P_CREATED)
> 			dev_put(rcu_dereference_protected(m->tcfm_dev, 1));
> 		dev_hold(dev);
>@@ -318,7 +317,7 @@ static struct net_device *tcf_mirred_get_dev(const struct tc_action *a)
> {
> 	struct tcf_mirred *m = to_mirred(a);
> 
>-	return __dev_get_by_index(m->net, m->tcfm_ifindex);
>+	return rtnl_dereference(m->tcfm_dev);
> }
> 
> static struct tc_action_ops act_mirred_ops = {
>-- 
>2.13.0
>