From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiri Pirko Subject: [patch net-next v3 2/2] net: core: introduce mini_Qdisc and eliminate usage of tp->q for clsact fastpath Date: Tue, 31 Oct 2017 16:12:22 +0100 Message-ID: <20171031151222.5021-3-jiri@resnulli.us> References: <20171031151222.5021-1-jiri@resnulli.us> Cc: davem@davemloft.net, jhs@mojatatu.com, xiyou.wangcong@gmail.com, mlxsw@mellanox.com, edumazet@google.com, daniel@iogearbox.net, alexander.h.duyck@intel.com, willemb@google.com, john.fastabend@gmail.com, alexei.starovoitov@gmail.com To: netdev@vger.kernel.org Return-path: Received: from mail-wr0-f194.google.com ([209.85.128.194]:47999 "EHLO mail-wr0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753298AbdJaPM0 (ORCPT ); Tue, 31 Oct 2017 11:12:26 -0400 Received: by mail-wr0-f194.google.com with SMTP id y39so16275319wrd.4 for ; Tue, 31 Oct 2017 08:12:25 -0700 (PDT) In-Reply-To: <20171031151222.5021-1-jiri@resnulli.us> Sender: netdev-owner@vger.kernel.org List-ID: From: Jiri Pirko In sch_handle_egress and sch_handle_ingress tp->q is used only in order to update stats. So stats and filter list are the only things that are needed in clsact qdisc fastpath processing. Introduce new mini_Qdisc struct to hold those items. Also, introduce a helper to swap the mini_Qdisc structures in case filter list head changes. This removes need for tp->q usage without added overhead. Signed-off-by: Jiri Pirko --- v2->v3: - Using head change callback to replace miniq pointer every time tp head changes. This eliminates one rcu dereference and makes the claim "without added overhead" valid. v1->v2: - Use dev instead of skb->dev in sch_handle_egress as pointed out by Daniel - Fixed synchronize_rcu_bh() in mini_qdisc_disable and commented --- include/linux/netdevice.h | 9 ++++++--- include/net/sch_generic.h | 32 ++++++++++++++++++++++++++++++++ net/core/dev.c | 21 +++++++++++---------- net/sched/sch_generic.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ net/sched/sch_ingress.c | 19 ++++++++++++++----- 5 files changed, 109 insertions(+), 18 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 5e02f79..7de7656 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -1559,6 +1559,8 @@ enum netdev_priv_flags { * * @rx_handler: handler for received packets * @rx_handler_data: XXX: need comments on this one + * @miniq_ingress: ingress/clsact qdisc specific data for + * ingress processing * @ingress_queue: XXX: need comments on this one * @broadcast: hw bcast address * @@ -1576,7 +1578,8 @@ enum netdev_priv_flags { * @tx_global_lock: XXX: need comments on this one * * @xps_maps: XXX: need comments on this one - * + * @miniq_egress: clsact qdisc specific data for + * egress processing * @watchdog_timeo: Represents the timeout that is used by * the watchdog (see dev_watchdog()) * @watchdog_timer: List of timers @@ -1795,7 +1798,7 @@ struct net_device { void __rcu *rx_handler_data; #ifdef CONFIG_NET_CLS_ACT - struct tcf_proto __rcu *ingress_cl_list; + struct mini_Qdisc __rcu *miniq_ingress; #endif struct netdev_queue __rcu *ingress_queue; #ifdef CONFIG_NETFILTER_INGRESS @@ -1826,7 +1829,7 @@ struct net_device { struct xps_dev_maps __rcu *xps_maps; #endif #ifdef CONFIG_NET_CLS_ACT - struct tcf_proto __rcu *egress_cl_list; + struct mini_Qdisc __rcu *miniq_egress; #endif /* These may be needed for future network-power-down code. */ diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h index 16d0f8f..f670272 100644 --- a/include/net/sch_generic.h +++ b/include/net/sch_generic.h @@ -897,4 +897,36 @@ static inline void psched_ratecfg_getrate(struct tc_ratespec *res, res->linklayer = (r->linklayer & TC_LINKLAYER_MASK); } +/* Mini Qdisc serves for specific needs of ingress/clsact Qdisc. + * The fast path only needs to access filter list and to update stats + */ +struct mini_Qdisc { + struct tcf_proto *filter_list; + struct gnet_stats_basic_cpu __percpu *cpu_bstats; + struct gnet_stats_queue __percpu *cpu_qstats; + struct rcu_head rcu; +}; + +static inline void mini_qdisc_bstats_cpu_update(struct mini_Qdisc *miniq, + const struct sk_buff *skb) +{ + bstats_cpu_update(this_cpu_ptr(miniq->cpu_bstats), skb); +} + +static inline void mini_qdisc_qstats_cpu_drop(struct mini_Qdisc *miniq) +{ + this_cpu_inc(miniq->cpu_qstats->drops); +} + +struct mini_Qdisc_pair { + struct mini_Qdisc miniq1; + struct mini_Qdisc miniq2; + struct mini_Qdisc __rcu **p_miniq; +}; + +void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp, + struct tcf_proto *tp_head); +void mini_qdisc_pair_init(struct mini_Qdisc_pair *miniqp, struct Qdisc *qdisc, + struct mini_Qdisc __rcu **p_miniq); + #endif diff --git a/net/core/dev.c b/net/core/dev.c index 24ac908..1423cf4 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -3274,22 +3274,22 @@ EXPORT_SYMBOL(dev_loopback_xmit); static struct sk_buff * sch_handle_egress(struct sk_buff *skb, int *ret, struct net_device *dev) { - struct tcf_proto *cl = rcu_dereference_bh(dev->egress_cl_list); + struct mini_Qdisc *miniq = rcu_dereference_bh(dev->miniq_egress); struct tcf_result cl_res; - if (!cl) + if (!miniq) return skb; /* qdisc_skb_cb(skb)->pkt_len was already set by the caller. */ - qdisc_bstats_cpu_update(cl->q, skb); + mini_qdisc_bstats_cpu_update(miniq, skb); - switch (tcf_classify(skb, cl, &cl_res, false)) { + switch (tcf_classify(skb, miniq->filter_list, &cl_res, false)) { case TC_ACT_OK: case TC_ACT_RECLASSIFY: skb->tc_index = TC_H_MIN(cl_res.classid); break; case TC_ACT_SHOT: - qdisc_qstats_cpu_drop(cl->q); + mini_qdisc_qstats_cpu_drop(miniq); *ret = NET_XMIT_DROP; kfree_skb(skb); return NULL; @@ -4189,7 +4189,7 @@ sch_handle_ingress(struct sk_buff *skb, struct packet_type **pt_prev, int *ret, struct net_device *orig_dev) { #ifdef CONFIG_NET_CLS_ACT - struct tcf_proto *cl = rcu_dereference_bh(skb->dev->ingress_cl_list); + struct mini_Qdisc *miniq = rcu_dereference_bh(skb->dev->miniq_ingress); struct tcf_result cl_res; /* If there's at least one ingress present somewhere (so @@ -4197,8 +4197,9 @@ sch_handle_ingress(struct sk_buff *skb, struct packet_type **pt_prev, int *ret, * that are not configured with an ingress qdisc will bail * out here. */ - if (!cl) + if (!miniq) return skb; + if (*pt_prev) { *ret = deliver_skb(skb, *pt_prev, orig_dev); *pt_prev = NULL; @@ -4206,15 +4207,15 @@ sch_handle_ingress(struct sk_buff *skb, struct packet_type **pt_prev, int *ret, qdisc_skb_cb(skb)->pkt_len = skb->len; skb->tc_at_ingress = 1; - qdisc_bstats_cpu_update(cl->q, skb); + mini_qdisc_bstats_cpu_update(miniq, skb); - switch (tcf_classify(skb, cl, &cl_res, false)) { + switch (tcf_classify(skb, miniq->filter_list, &cl_res, false)) { case TC_ACT_OK: case TC_ACT_RECLASSIFY: skb->tc_index = TC_H_MIN(cl_res.classid); break; case TC_ACT_SHOT: - qdisc_qstats_cpu_drop(cl->q); + mini_qdisc_qstats_cpu_drop(miniq); kfree_skb(skb); return NULL; case TC_ACT_STOLEN: diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c index aa74aa4..3839cbb 100644 --- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -1024,3 +1024,49 @@ void psched_ratecfg_precompute(struct psched_ratecfg *r, } } EXPORT_SYMBOL(psched_ratecfg_precompute); + +static void mini_qdisc_rcu_func(struct rcu_head *head) +{ +} + +void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp, + struct tcf_proto *tp_head) +{ + struct mini_Qdisc *miniq_old = rtnl_dereference(*miniqp->p_miniq); + struct mini_Qdisc *miniq; + + if (!tp_head) { + RCU_INIT_POINTER(*miniqp->p_miniq, NULL); + return; + } + + miniq = !miniq_old || miniq_old == &miniqp->miniq2 ? + &miniqp->miniq1 : &miniqp->miniq2; + + /* We need to make sure that readers won't see the miniq + * we are about to modify. So wait until previous call_rcu_bh callback + * is done. + */ + rcu_barrier_bh(); + miniq->filter_list = tp_head; + rcu_assign_pointer(*miniqp->p_miniq, miniq); + + if (miniq_old) + /* This is counterpart of the rcu barrier above. We need to + * block potential new user of miniq_old until all readers + * are not seeing it. + */ + call_rcu_bh(&miniq_old->rcu, mini_qdisc_rcu_func); +} +EXPORT_SYMBOL(mini_qdisc_pair_swap); + +void mini_qdisc_pair_init(struct mini_Qdisc_pair *miniqp, struct Qdisc *qdisc, + struct mini_Qdisc __rcu **p_miniq) +{ + miniqp->miniq1.cpu_bstats = qdisc->cpu_bstats; + miniqp->miniq1.cpu_qstats = qdisc->cpu_qstats; + miniqp->miniq2.cpu_bstats = qdisc->cpu_bstats; + miniqp->miniq2.cpu_qstats = qdisc->cpu_qstats; + miniqp->p_miniq = p_miniq; +} +EXPORT_SYMBOL(mini_qdisc_pair_init); diff --git a/net/sched/sch_ingress.c b/net/sched/sch_ingress.c index 8118458..5ecc38f 100644 --- a/net/sched/sch_ingress.c +++ b/net/sched/sch_ingress.c @@ -21,6 +21,7 @@ struct ingress_sched_data { struct tcf_block *block; struct tcf_block_ext_info block_info; + struct mini_Qdisc_pair miniqp; }; static struct Qdisc *ingress_leaf(struct Qdisc *sch, unsigned long arg) @@ -56,9 +57,9 @@ static struct tcf_block *ingress_tcf_block(struct Qdisc *sch, unsigned long cl) static void clsact_chain_head_change(struct tcf_proto *tp_head, void *priv) { - struct tcf_proto __rcu **p_filter_chain = priv; + struct mini_Qdisc_pair *miniqp = priv; - rcu_assign_pointer(*p_filter_chain, tp_head); + mini_qdisc_pair_swap(miniqp, tp_head); } static int ingress_init(struct Qdisc *sch, struct nlattr *opt) @@ -67,9 +68,11 @@ static int ingress_init(struct Qdisc *sch, struct nlattr *opt) struct net_device *dev = qdisc_dev(sch); int err; + mini_qdisc_pair_init(&q->miniqp, sch, &dev->miniq_ingress); + q->block_info.binder_type = TCF_BLOCK_BINDER_TYPE_CLSACT_INGRESS; q->block_info.chain_head_change = clsact_chain_head_change; - q->block_info.chain_head_change_priv = &dev->ingress_cl_list; + q->block_info.chain_head_change_priv = &q->miniqp; err = tcf_block_get_ext(&q->block, sch, &q->block_info); if (err) @@ -128,6 +131,8 @@ struct clsact_sched_data { struct tcf_block *egress_block; struct tcf_block_ext_info ingress_block_info; struct tcf_block_ext_info egress_block_info; + struct mini_Qdisc_pair miniqp_ingress; + struct mini_Qdisc_pair miniqp_egress; }; static unsigned long clsact_find(struct Qdisc *sch, u32 classid) @@ -167,17 +172,21 @@ static int clsact_init(struct Qdisc *sch, struct nlattr *opt) struct net_device *dev = qdisc_dev(sch); int err; + mini_qdisc_pair_init(&q->miniqp_ingress, sch, &dev->miniq_ingress); + q->ingress_block_info.binder_type = TCF_BLOCK_BINDER_TYPE_CLSACT_INGRESS; q->ingress_block_info.chain_head_change = clsact_chain_head_change; - q->ingress_block_info.chain_head_change_priv = &dev->ingress_cl_list; + q->ingress_block_info.chain_head_change_priv = &q->miniqp_ingress; err = tcf_block_get_ext(&q->ingress_block, sch, &q->ingress_block_info); if (err) return err; + mini_qdisc_pair_init(&q->miniqp_egress, sch, &dev->miniq_egress); + q->egress_block_info.binder_type = TCF_BLOCK_BINDER_TYPE_CLSACT_EGRESS; q->egress_block_info.chain_head_change = clsact_chain_head_change; - q->egress_block_info.chain_head_change_priv = &dev->egress_cl_list; + q->egress_block_info.chain_head_change_priv = &q->miniqp_egress; err = tcf_block_get_ext(&q->egress_block, sch, &q->egress_block_info); if (err) -- 2.9.5