[PATCH net-next v5 4/4] act_mirred: use TC_ACT_REINSERT when possible
From: Paolo Abeni <pabeni@redhat.com>
Date: 2018-07-30 14:05:53
Subsystem:
networking [general], tc subsystem, the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Jamal Hadi Salim, Jiri Pirko, Linus Torvalds
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: Paolo Abeni <pabeni@redhat.com> --- Note: I had to do some minor change in the last chunk since v4, so I did not include Cong's ack, added to such revision --- net/sched/act_mirred.c | 53 ++++++++++++++++++++++++++++++++++-------- 1 file changed, 43 insertions(+), 10 deletions(-)
diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c
index eeb335f03102..b26d060da08e 100644
--- a/net/sched/act_mirred.c
+++ b/net/sched/act_mirred.c@@ -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; } - skb2 = skb_clone(skb, GFP_ATOMIC); - if (!skb2) - 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);
--
2.17.1