Commit e5cf1baf authored by Paolo Abeni's avatar Paolo Abeni Committed by David S. Miller
Browse files

act_mirred: use TC_ACT_REINSERT when possible 



When mirred is invoked from the ingress path, and it wants to redirect
the processed packet, it can now use the TC_ACT_REINSERT action,
filling the tcf_result accordingly, and avoiding a per packet
skb_clone().

Overall this gives a ~10% improvement in forwarding performance for the
TC S/W data path and TC S/W performances are now comparable to the
kernel openvswitch datapath.

v1 -> v2: use ACT_MIRRED instead of ACT_REDIRECT
v2 -> v3: updated after action rename, fixed typo into the commit
	message
v3 -> v4: updated again after action rename, added more comments to
	the code (JiriP), skip the optimization if the control action
	need to touch the tcf_result (Paolo)
v4 -> v5: fix sparse warning (kbuild bot)

Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
Acked-by: default avatarJiri Pirko <jiri@mellanox.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent cd11b164

net/sched/act_mirred.c

+43 −10
Original line number Diff line number Diff line
@@ -25,6 +25,7 @@ 
#include <net/net_namespace.h>

#include <net/netlink.h>

#include <net/pkt_sched.h>

#include <net/pkt_cls.h>

#include <linux/tc_act/tc_mirred.h>

#include <net/tc_act/tc_mirred.h>
@@ -49,6 +50,18 @@ static bool tcf_mirred_act_wants_ingress(int action) 
	}

}



static bool tcf_mirred_can_reinsert(int action)

{

	switch (action) {

	case TC_ACT_SHOT:

	case TC_ACT_STOLEN:

	case TC_ACT_QUEUED:

	case TC_ACT_TRAP:

		return true;

	}

	return false;

}



static void tcf_mirred_release(struct tc_action *a)

{

	struct tcf_mirred *m = to_mirred(a);
@@ -171,10 +184,13 @@ static int tcf_mirred(struct sk_buff *skb, const struct tc_action *a, 
		      struct tcf_result *res)

{

	struct tcf_mirred *m = to_mirred(a);

	struct sk_buff *skb2 = skb;

	bool m_mac_header_xmit;

	struct net_device *dev;

	struct sk_buff *skb2;

	int retval, err = 0;

	bool use_reinsert;

	bool want_ingress;

	bool is_redirect;

	int m_eaction;

	int mac_len;
@@ -196,16 +212,25 @@ static int tcf_mirred(struct sk_buff *skb, const struct tc_action *a, 
		goto out;

	}



	/* we could easily avoid the clone only if called by ingress and clsact;

	 * since we can't easily detect the clsact caller, skip clone only for

	 * ingress - that covers the TC S/W datapath.

	 */

	is_redirect = tcf_mirred_is_act_redirect(m_eaction);

	use_reinsert = skb_at_tc_ingress(skb) && is_redirect &&

		       tcf_mirred_can_reinsert(retval);

	if (!use_reinsert) {

		skb2 = skb_clone(skb, GFP_ATOMIC);

		if (!skb2)

			goto out;

	}



	/* If action's target direction differs than filter's direction,

	 * and devices expect a mac header on xmit, then mac push/pull is

	 * needed.

	 */

	if (skb_at_tc_ingress(skb) != tcf_mirred_act_wants_ingress(m_eaction) &&

	    m_mac_header_xmit) {

	want_ingress = tcf_mirred_act_wants_ingress(m_eaction);

	if (skb_at_tc_ingress(skb) != want_ingress && m_mac_header_xmit) {

		if (!skb_at_tc_ingress(skb)) {

			/* caught at egress, act ingress: pull mac */

			mac_len = skb_network_header(skb) - skb_mac_header(skb);
@@ -216,15 +241,23 @@ static int tcf_mirred(struct sk_buff *skb, const struct tc_action *a, 
		}

	}



	skb2->skb_iif = skb->dev->ifindex;

	skb2->dev = dev;



	/* mirror is always swallowed */

	if (tcf_mirred_is_act_redirect(m_eaction)) {

	if (is_redirect) {

		skb2->tc_redirected = 1;

		skb2->tc_from_ingress = skb2->tc_at_ingress;



		/* let's the caller reinsert the packet, if possible */

		if (use_reinsert) {

			res->ingress = want_ingress;

			res->qstats = this_cpu_ptr(m->common.cpu_qstats);

			return TC_ACT_REINSERT;

		}

	}



	skb2->skb_iif = skb->dev->ifindex;

	skb2->dev = dev;

	if (!tcf_mirred_act_wants_ingress(m_eaction))

	if (!want_ingress)

		err = dev_queue_xmit(skb2);

	else

		err = netif_receive_skb(skb2);

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