netdev - Re: [PATCH 1/6] [net-next]net: sched: act_mirred: Extend redirect action to accept a traffic class

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Message-ID: <20170801111203.GI1939@nanopsycho>
Date:   Tue, 1 Aug 2017 13:12:03 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     Amritha Nambiar <amritha.nambiar@...el.com>
Cc:     intel-wired-lan@...ts.osuosl.org, jeffrey.t.kirsher@...el.com,
        alexander.h.duyck@...el.com, kiran.patil@...el.com,
        netdev@...r.kernel.org, mitch.a.williams@...el.com,
        alexander.duyck@...il.com, neerav.parikh@...el.com,
        sridhar.samudrala@...el.com, carolyn.wyborny@...el.com
Subject: Re: [PATCH 1/6] [net-next]net: sched: act_mirred: Extend redirect
 action to accept a traffic class

Tue, Aug 01, 2017 at 02:37:37AM CEST, amritha.nambiar@...el.com wrote:
>The Mirred/redirect action is extended to forward to a traffic
>class on the device. The traffic class index needs to be
>provided in addition to the device's ifindex.
>
>Example:
># tc filter add dev eth0 protocol ip parent ffff: prio 1 flower\
>  dst_ip 192.168.1.1/32 ip_proto udp dst_port 22\
>  skip_sw indev eth0 action mirred ingress redirect dev eth0 tc 1

You need to make sure that the current offloaders fill forbid to add
this rule, not just silently ignore the tc value.


>
>Signed-off-by: Amritha Nambiar <amritha.nambiar@...el.com>
>---
> include/net/tc_act/tc_mirred.h        |    7 +++++++
> include/uapi/linux/tc_act/tc_mirred.h |    5 +++++
> net/sched/act_mirred.c                |   17 +++++++++++++++++
> 3 files changed, 29 insertions(+)
>
>diff --git a/include/net/tc_act/tc_mirred.h b/include/net/tc_act/tc_mirred.h
>index 604bc31..60058c4 100644
>--- a/include/net/tc_act/tc_mirred.h
>+++ b/include/net/tc_act/tc_mirred.h
>@@ -9,6 +9,8 @@ struct tcf_mirred {
> 	int			tcfm_eaction;
> 	int			tcfm_ifindex;
> 	bool			tcfm_mac_header_xmit;
>+	u8			tcfm_tc;
>+	u32			flags;
> 	struct net_device __rcu	*tcfm_dev;
> 	struct list_head	tcfm_list;
> };
>@@ -37,4 +39,9 @@ static inline int tcf_mirred_ifindex(const struct tc_action *a)
> 	return to_mirred(a)->tcfm_ifindex;
> }
> 
>+static inline int tcf_mirred_tc(const struct tc_action *a)
>+{
>+	return to_mirred(a)->tcfm_tc;
>+}
>+
> #endif /* __NET_TC_MIR_H */
>diff --git a/include/uapi/linux/tc_act/tc_mirred.h b/include/uapi/linux/tc_act/tc_mirred.h
>index 3d7a2b3..8ff4d76 100644
>--- a/include/uapi/linux/tc_act/tc_mirred.h
>+++ b/include/uapi/linux/tc_act/tc_mirred.h
>@@ -9,6 +9,10 @@
> #define TCA_EGRESS_MIRROR 2 /* mirror packet to EGRESS */
> #define TCA_INGRESS_REDIR 3  /* packet redirect to INGRESS*/
> #define TCA_INGRESS_MIRROR 4 /* mirror packet to INGRESS */
>+
>+#define MIRRED_F_TC_MAP		0x1
>+#define MIRRED_TC_MAP_MAX	0x10
>+#define MIRRED_TC_MAP_MASK	0xF

I'm completely lost. Why do you have these values here? and in fact one
twice?


>                                                                                 
> struct tc_mirred {
> 	tc_gen;
>@@ -21,6 +25,7 @@ enum {
> 	TCA_MIRRED_TM,
> 	TCA_MIRRED_PARMS,
> 	TCA_MIRRED_PAD,
>+	TCA_MIRRED_TC_MAP,
> 	__TCA_MIRRED_MAX
> };
> #define TCA_MIRRED_MAX (__TCA_MIRRED_MAX - 1)
>diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c
>index 1b5549a..f9801de 100644
>--- a/net/sched/act_mirred.c
>+++ b/net/sched/act_mirred.c
>@@ -67,6 +67,7 @@ static void tcf_mirred_release(struct tc_action *a, int bind)
> 
> static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = {
> 	[TCA_MIRRED_PARMS]	= { .len = sizeof(struct tc_mirred) },
>+	[TCA_MIRRED_TC_MAP]	= { .type = NLA_U8 },
> };
> 
> static unsigned int mirred_net_id;
>@@ -83,6 +84,8 @@ static int tcf_mirred_init(struct net *net, struct nlattr *nla,
> 	struct tcf_mirred *m;
> 	struct net_device *dev;
> 	bool exists = false;
>+	u8 *tc_map = NULL;
>+	u32 flags = 0;
> 	int ret;
> 
> 	if (nla == NULL)
>@@ -92,6 +95,14 @@ static int tcf_mirred_init(struct net *net, struct nlattr *nla,
> 		return ret;
> 	if (tb[TCA_MIRRED_PARMS] == NULL)
> 		return -EINVAL;
>+
>+	if (tb[TCA_MIRRED_TC_MAP]) {
>+		tc_map = nla_data(tb[TCA_MIRRED_TC_MAP]);
>+		if (*tc_map >= MIRRED_TC_MAP_MAX)
>+			return -EINVAL;
>+		flags |= MIRRED_F_TC_MAP;
>+	}
>+
> 	parm = nla_data(tb[TCA_MIRRED_PARMS]);
> 
> 	exists = tcf_hash_check(tn, parm->index, a, bind);
>@@ -139,6 +150,7 @@ static int tcf_mirred_init(struct net *net, struct nlattr *nla,
> 	ASSERT_RTNL();
> 	m->tcf_action = parm->action;
> 	m->tcfm_eaction = parm->eaction;
>+	m->flags = flags;
> 	if (dev != NULL) {
> 		m->tcfm_ifindex = parm->ifindex;
> 		if (ret != ACT_P_CREATED)
>@@ -146,6 +158,8 @@ static int tcf_mirred_init(struct net *net, struct nlattr *nla,
> 		dev_hold(dev);
> 		rcu_assign_pointer(m->tcfm_dev, dev);
> 		m->tcfm_mac_header_xmit = mac_header_xmit;
>+		if (flags & MIRRED_F_TC_MAP)
>+			m->tcfm_tc = *tc_map & MIRRED_TC_MAP_MASK;
> 	}
> 
> 	if (ret == ACT_P_CREATED) {
>@@ -259,6 +273,9 @@ static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind,
> 
> 	if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt))
> 		goto nla_put_failure;
>+	if ((m->flags & MIRRED_F_TC_MAP) &&
>+	    nla_put_u8(skb, TCA_MIRRED_TC_MAP, m->tcfm_tc))
>+		goto nla_put_failure;
> 
> 	tcf_tm_dump(&t, &m->tcf_tm);
> 	if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD))
>