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

On 8/1/2017 3:44 AM, Jamal Hadi Salim wrote:

On 17-07-31 08:37 PM, Amritha Nambiar wrote:

quoted

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

Signed-off-by: Amritha Nambiar <redacted>
---
  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
                                                                                  
  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;

quoted

+	}
+
  	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;
  	}
  

Is the mask a hardware limit. I dont know how these queues are
allocated - I am assuming each of these "tc queues" maps to a rx
DMA ring?

This is the bitmask for TC max range again defined in linux/netdevice.h.
I'll fix this to remove the new definition I have (MIRRED_TC_MAP_MASK)
here and replace with the existing TC_BITMASK. These are just the
traffic class index that are offloaded to the device. I had submitted
another series that handles configuring queues for the traffic classes
and queue layout offloaded via the mqprio framework.

quoted

  	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;

If you have m->tcfm_tc then I dont think you need the flags; so i would
remove it from the struct altogether.

I think I would still need the flags as "tc" index is an optional
parameter and the value zero is also a valid TC index. I was also
planning to use this flag to address Jiri's comment to fail this rule in
devices not supporting this offload.

cheers,
jamal