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net: core: introduce mini_Qdisc and eliminate usage of tp->q for clsa…
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…ct fastpath

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 <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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@jpirko @davem330
jpirko authored and davem330 committed Nov 3, 2017
1 parent c7eb7d7 commit 4620940
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Showing 5 changed files with 109 additions and 18 deletions.
9 changes: 6 additions & 3 deletions include/linux/netdevice.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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
*
Expand All @@ -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
Expand Down Expand Up @@ -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
Expand Down Expand Up @@ -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. */
Expand Down
32 changes: 32 additions & 0 deletions include/net/sch_generic.h
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Original file line number Diff line number Diff line change
Expand Up @@ -904,4 +904,36 @@ 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
21 changes: 11 additions & 10 deletions net/core/dev.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -4189,32 +4189,33 @@ 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
* we get here via enabled static key), remaining devices
* 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;
}

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:
Expand Down
46 changes: 46 additions & 0 deletions net/sched/sch_generic.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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);
19 changes: 14 additions & 5 deletions net/sched/sch_ingress.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand Down Expand Up @@ -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)
Expand All @@ -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)
Expand Down Expand Up @@ -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)
Expand Down Expand Up @@ -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)
Expand Down

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