sch_fq_codel.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Fair Queue CoDel discipline
  4 *
  5 *  Copyright (C) 2012,2015 Eric Dumazet <edumazet@google.com>
  6 */
  7
  8#include <linux/module.h>
  9#include <linux/types.h>
 10#include <linux/kernel.h>
 11#include <linux/jiffies.h>
 12#include <linux/string.h>
 13#include <linux/in.h>
 14#include <linux/errno.h>
 15#include <linux/init.h>
 16#include <linux/skbuff.h>
 17#include <linux/slab.h>
 18#include <linux/vmalloc.h>
 19#include <net/netlink.h>
 20#include <net/pkt_sched.h>
 21#include <net/pkt_cls.h>
 22#include <net/codel.h>
 23#include <net/codel_impl.h>
 24#include <net/codel_qdisc.h>
 25
 26/*	Fair Queue CoDel.
 27 *
 28 * Principles :
 29 * Packets are classified (internal classifier or external) on flows.
 30 * This is a Stochastic model (as we use a hash, several flows
 31 *			       might be hashed on same slot)
 32 * Each flow has a CoDel managed queue.
 33 * Flows are linked onto two (Round Robin) lists,
 34 * so that new flows have priority on old ones.
 35 *
 36 * For a given flow, packets are not reordered (CoDel uses a FIFO)
 37 * head drops only.
 38 * ECN capability is on by default.
 39 * Low memory footprint (64 bytes per flow)
 40 */
 41
 42struct fq_codel_flow {
 43	struct sk_buff	  *head;
 44	struct sk_buff	  *tail;
 45	struct list_head  flowchain;
 46	int		  deficit;
 47	struct codel_vars cvars;
 48}; /* please try to keep this structure <= 64 bytes */
 49
 50struct fq_codel_sched_data {
 51	struct tcf_proto __rcu *filter_list; /* optional external classifier */
 52	struct tcf_block *block;
 53	struct fq_codel_flow *flows;	/* Flows table [flows_cnt] */
 54	u32		*backlogs;	/* backlog table [flows_cnt] */
 55	u32		flows_cnt;	/* number of flows */
 56	u32		quantum;	/* psched_mtu(qdisc_dev(sch)); */
 57	u32		drop_batch_size;
 58	u32		memory_limit;
 59	struct codel_params cparams;
 60	struct codel_stats cstats;
 61	u32		memory_usage;
 62	u32		drop_overmemory;
 63	u32		drop_overlimit;
 64	u32		new_flow_count;
 65
 66	struct list_head new_flows;	/* list of new flows */
 67	struct list_head old_flows;	/* list of old flows */
 68};
 69
 70static unsigned int fq_codel_hash(const struct fq_codel_sched_data *q,
 71				  struct sk_buff *skb)
 72{
 73	return reciprocal_scale(skb_get_hash(skb), q->flows_cnt);
 74}
 75
 76static unsigned int fq_codel_classify(struct sk_buff *skb, struct Qdisc *sch,
 77				      int *qerr)
 78{
 79	struct fq_codel_sched_data *q = qdisc_priv(sch);
 80	struct tcf_proto *filter;
 81	struct tcf_result res;
 82	int result;
 83
 84	if (TC_H_MAJ(skb->priority) == sch->handle &&
 85	    TC_H_MIN(skb->priority) > 0 &&
 86	    TC_H_MIN(skb->priority) <= q->flows_cnt)
 87		return TC_H_MIN(skb->priority);
 88
 89	filter = rcu_dereference_bh(q->filter_list);
 90	if (!filter)
 91		return fq_codel_hash(q, skb) + 1;
 92
 93	*qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
 94	result = tcf_classify(skb, NULL, filter, &res, false);
 95	if (result >= 0) {
 96#ifdef CONFIG_NET_CLS_ACT
 97		switch (result) {
 98		case TC_ACT_STOLEN:
 99		case TC_ACT_QUEUED:
100		case TC_ACT_TRAP:
101			*qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
102			fallthrough;
103		case TC_ACT_SHOT:
104			return 0;
105		}
106#endif
107		if (TC_H_MIN(res.classid) <= q->flows_cnt)
108			return TC_H_MIN(res.classid);
109	}
110	return 0;
111}
112
113/* helper functions : might be changed when/if skb use a standard list_head */
114
115/* remove one skb from head of slot queue */
116static inline struct sk_buff *dequeue_head(struct fq_codel_flow *flow)
117{
118	struct sk_buff *skb = flow->head;
119
120	flow->head = skb->next;
121	skb_mark_not_on_list(skb);
122	return skb;
123}
124
125/* add skb to flow queue (tail add) */
126static inline void flow_queue_add(struct fq_codel_flow *flow,
127				  struct sk_buff *skb)
128{
129	if (flow->head == NULL)
130		flow->head = skb;
131	else
132		flow->tail->next = skb;
133	flow->tail = skb;
134	skb->next = NULL;
135}
136
137static unsigned int fq_codel_drop(struct Qdisc *sch, unsigned int max_packets,
138				  struct sk_buff **to_free)
139{
140	struct fq_codel_sched_data *q = qdisc_priv(sch);
141	struct sk_buff *skb;
142	unsigned int maxbacklog = 0, idx = 0, i, len;
143	struct fq_codel_flow *flow;
144	unsigned int threshold;
145	unsigned int mem = 0;
146
147	/* Queue is full! Find the fat flow and drop packet(s) from it.
148	 * This might sound expensive, but with 1024 flows, we scan
149	 * 4KB of memory, and we dont need to handle a complex tree
150	 * in fast path (packet queue/enqueue) with many cache misses.
151	 * In stress mode, we'll try to drop 64 packets from the flow,
152	 * amortizing this linear lookup to one cache line per drop.
153	 */
154	for (i = 0; i < q->flows_cnt; i++) {
155		if (q->backlogs[i] > maxbacklog) {
156			maxbacklog = q->backlogs[i];
157			idx = i;
158		}
159	}
160
161	/* Our goal is to drop half of this fat flow backlog */
162	threshold = maxbacklog >> 1;
163
164	flow = &q->flows[idx];
165	len = 0;
166	i = 0;
167	do {
168		skb = dequeue_head(flow);
169		len += qdisc_pkt_len(skb);
170		mem += get_codel_cb(skb)->mem_usage;
171		tcf_set_drop_reason(skb, SKB_DROP_REASON_QDISC_OVERLIMIT);
172		__qdisc_drop(skb, to_free);
173	} while (++i < max_packets && len < threshold);
174
175	/* Tell codel to increase its signal strength also */
176	flow->cvars.count += i;
177	q->backlogs[idx] -= len;
178	q->memory_usage -= mem;
179	sch->qstats.drops += i;
180	sch->qstats.backlog -= len;
181	sch->q.qlen -= i;
182	return idx;
183}
184
185static int fq_codel_enqueue(struct sk_buff *skb, struct Qdisc *sch,
186			    struct sk_buff **to_free)
187{
188	struct fq_codel_sched_data *q = qdisc_priv(sch);
189	unsigned int idx, prev_backlog, prev_qlen;
190	struct fq_codel_flow *flow;
191	int ret;
192	unsigned int pkt_len;
193	bool memory_limited;
194
195	idx = fq_codel_classify(skb, sch, &ret);
196	if (idx == 0) {
197		if (ret & __NET_XMIT_BYPASS)
198			qdisc_qstats_drop(sch);
199		__qdisc_drop(skb, to_free);
200		return ret;
201	}
202	idx--;
203
204	codel_set_enqueue_time(skb);
205	flow = &q->flows[idx];
206	flow_queue_add(flow, skb);
207	q->backlogs[idx] += qdisc_pkt_len(skb);
208	qdisc_qstats_backlog_inc(sch, skb);
209
210	if (list_empty(&flow->flowchain)) {
211		list_add_tail(&flow->flowchain, &q->new_flows);
212		q->new_flow_count++;
213		flow->deficit = q->quantum;
214	}
215	get_codel_cb(skb)->mem_usage = skb->truesize;
216	q->memory_usage += get_codel_cb(skb)->mem_usage;
217	memory_limited = q->memory_usage > q->memory_limit;
218	if (++sch->q.qlen <= sch->limit && !memory_limited)
219		return NET_XMIT_SUCCESS;
220
221	prev_backlog = sch->qstats.backlog;
222	prev_qlen = sch->q.qlen;
223
224	/* save this packet length as it might be dropped by fq_codel_drop() */
225	pkt_len = qdisc_pkt_len(skb);
226	/* fq_codel_drop() is quite expensive, as it performs a linear search
227	 * in q->backlogs[] to find a fat flow.
228	 * So instead of dropping a single packet, drop half of its backlog
229	 * with a 64 packets limit to not add a too big cpu spike here.
230	 */
231	ret = fq_codel_drop(sch, q->drop_batch_size, to_free);
232
233	prev_qlen -= sch->q.qlen;
234	prev_backlog -= sch->qstats.backlog;
235	q->drop_overlimit += prev_qlen;
236	if (memory_limited)
237		q->drop_overmemory += prev_qlen;
238
239	/* As we dropped packet(s), better let upper stack know this.
240	 * If we dropped a packet for this flow, return NET_XMIT_CN,
241	 * but in this case, our parents wont increase their backlogs.
242	 */
243	if (ret == idx) {
244		qdisc_tree_reduce_backlog(sch, prev_qlen - 1,
245					  prev_backlog - pkt_len);
246		return NET_XMIT_CN;
247	}
248	qdisc_tree_reduce_backlog(sch, prev_qlen, prev_backlog);
249	return NET_XMIT_SUCCESS;
250}
251
252/* This is the specific function called from codel_dequeue()
253 * to dequeue a packet from queue. Note: backlog is handled in
254 * codel, we dont need to reduce it here.
255 */
256static struct sk_buff *dequeue_func(struct codel_vars *vars, void *ctx)
257{
258	struct Qdisc *sch = ctx;
259	struct fq_codel_sched_data *q = qdisc_priv(sch);
260	struct fq_codel_flow *flow;
261	struct sk_buff *skb = NULL;
262
263	flow = container_of(vars, struct fq_codel_flow, cvars);
264	if (flow->head) {
265		skb = dequeue_head(flow);
266		q->backlogs[flow - q->flows] -= qdisc_pkt_len(skb);
267		q->memory_usage -= get_codel_cb(skb)->mem_usage;
268		sch->q.qlen--;
269		sch->qstats.backlog -= qdisc_pkt_len(skb);
270	}
271	return skb;
272}
273
274static void drop_func(struct sk_buff *skb, void *ctx)
275{
276	struct Qdisc *sch = ctx;
277
278	qdisc_dequeue_drop(sch, skb, SKB_DROP_REASON_QDISC_CONGESTED);
279	qdisc_qstats_drop(sch);
280}
281
282static struct sk_buff *fq_codel_dequeue(struct Qdisc *sch)
283{
284	struct fq_codel_sched_data *q = qdisc_priv(sch);
285	struct sk_buff *skb;
286	struct fq_codel_flow *flow;
287	struct list_head *head;
288
289begin:
290	head = &q->new_flows;
291	if (list_empty(head)) {
292		head = &q->old_flows;
293		if (list_empty(head))
294			return NULL;
295	}
296	flow = list_first_entry(head, struct fq_codel_flow, flowchain);
297
298	if (flow->deficit <= 0) {
299		flow->deficit += q->quantum;
300		list_move_tail(&flow->flowchain, &q->old_flows);
301		goto begin;
302	}
303
304	skb = codel_dequeue(sch, &sch->qstats.backlog, &q->cparams,
305			    &flow->cvars, &q->cstats, qdisc_pkt_len,
306			    codel_get_enqueue_time, drop_func, dequeue_func);
307
308	if (!skb) {
309		/* force a pass through old_flows to prevent starvation */
310		if ((head == &q->new_flows) && !list_empty(&q->old_flows))
311			list_move_tail(&flow->flowchain, &q->old_flows);
312		else
313			list_del_init(&flow->flowchain);
314		goto begin;
315	}
316	qdisc_bstats_update(sch, skb);
317	flow->deficit -= qdisc_pkt_len(skb);
318
319	if (q->cstats.drop_count) {
320		qdisc_tree_reduce_backlog(sch, q->cstats.drop_count,
321					  q->cstats.drop_len);
322		q->cstats.drop_count = 0;
323		q->cstats.drop_len = 0;
324	}
325	return skb;
326}
327
328static void fq_codel_flow_purge(struct fq_codel_flow *flow)
329{
330	rtnl_kfree_skbs(flow->head, flow->tail);
331	flow->head = NULL;
332}
333
334static void fq_codel_reset(struct Qdisc *sch)
335{
336	struct fq_codel_sched_data *q = qdisc_priv(sch);
337	int i;
338
339	INIT_LIST_HEAD(&q->new_flows);
340	INIT_LIST_HEAD(&q->old_flows);
341	for (i = 0; i < q->flows_cnt; i++) {
342		struct fq_codel_flow *flow = q->flows + i;
343
344		fq_codel_flow_purge(flow);
345		INIT_LIST_HEAD(&flow->flowchain);
346		codel_vars_init(&flow->cvars);
347	}
348	memset(q->backlogs, 0, q->flows_cnt * sizeof(u32));
349	q->memory_usage = 0;
350}
351
352static const struct nla_policy fq_codel_policy[TCA_FQ_CODEL_MAX + 1] = {
353	[TCA_FQ_CODEL_TARGET]	= { .type = NLA_U32 },
354	[TCA_FQ_CODEL_LIMIT]	= { .type = NLA_U32 },
355	[TCA_FQ_CODEL_INTERVAL]	= { .type = NLA_U32 },
356	[TCA_FQ_CODEL_ECN]	= { .type = NLA_U32 },
357	[TCA_FQ_CODEL_FLOWS]	= { .type = NLA_U32 },
358	[TCA_FQ_CODEL_QUANTUM]	= { .type = NLA_U32 },
359	[TCA_FQ_CODEL_CE_THRESHOLD] = { .type = NLA_U32 },
360	[TCA_FQ_CODEL_DROP_BATCH_SIZE] = { .type = NLA_U32 },
361	[TCA_FQ_CODEL_MEMORY_LIMIT] = { .type = NLA_U32 },
362	[TCA_FQ_CODEL_CE_THRESHOLD_SELECTOR] = { .type = NLA_U8 },
363	[TCA_FQ_CODEL_CE_THRESHOLD_MASK] = { .type = NLA_U8 },
364};
365
366static int fq_codel_change(struct Qdisc *sch, struct nlattr *opt,
367			   struct netlink_ext_ack *extack)
368{
369	unsigned int dropped_pkts = 0, dropped_bytes = 0;
370	struct fq_codel_sched_data *q = qdisc_priv(sch);
371	struct nlattr *tb[TCA_FQ_CODEL_MAX + 1];
372	u32 quantum = 0;
373	int err;
374
375	err = nla_parse_nested_deprecated(tb, TCA_FQ_CODEL_MAX, opt,
376					  fq_codel_policy, NULL);
377	if (err < 0)
378		return err;
379	if (tb[TCA_FQ_CODEL_FLOWS]) {
380		if (q->flows)
381			return -EINVAL;
382		q->flows_cnt = nla_get_u32(tb[TCA_FQ_CODEL_FLOWS]);
383		if (!q->flows_cnt ||
384		    q->flows_cnt > 65536)
385			return -EINVAL;
386	}
387	if (tb[TCA_FQ_CODEL_QUANTUM]) {
388		quantum = max(256U, nla_get_u32(tb[TCA_FQ_CODEL_QUANTUM]));
389		if (quantum > FQ_CODEL_QUANTUM_MAX) {
390			NL_SET_ERR_MSG(extack, "Invalid quantum");
391			return -EINVAL;
392		}
393	}
394	sch_tree_lock(sch);
395
396	if (tb[TCA_FQ_CODEL_TARGET]) {
397		u64 target = nla_get_u32(tb[TCA_FQ_CODEL_TARGET]);
398
399		WRITE_ONCE(q->cparams.target,
400			   (target * NSEC_PER_USEC) >> CODEL_SHIFT);
401	}
402
403	if (tb[TCA_FQ_CODEL_CE_THRESHOLD]) {
404		u64 val = nla_get_u32(tb[TCA_FQ_CODEL_CE_THRESHOLD]);
405
406		WRITE_ONCE(q->cparams.ce_threshold,
407			   (val * NSEC_PER_USEC) >> CODEL_SHIFT);
408	}
409
410	if (tb[TCA_FQ_CODEL_CE_THRESHOLD_SELECTOR])
411		WRITE_ONCE(q->cparams.ce_threshold_selector,
412			   nla_get_u8(tb[TCA_FQ_CODEL_CE_THRESHOLD_SELECTOR]));
413	if (tb[TCA_FQ_CODEL_CE_THRESHOLD_MASK])
414		WRITE_ONCE(q->cparams.ce_threshold_mask,
415			   nla_get_u8(tb[TCA_FQ_CODEL_CE_THRESHOLD_MASK]));
416
417	if (tb[TCA_FQ_CODEL_INTERVAL]) {
418		u64 interval = nla_get_u32(tb[TCA_FQ_CODEL_INTERVAL]);
419
420		WRITE_ONCE(q->cparams.interval,
421			   (interval * NSEC_PER_USEC) >> CODEL_SHIFT);
422	}
423
424	if (tb[TCA_FQ_CODEL_LIMIT])
425		WRITE_ONCE(sch->limit,
426			   nla_get_u32(tb[TCA_FQ_CODEL_LIMIT]));
427
428	if (tb[TCA_FQ_CODEL_ECN])
429		WRITE_ONCE(q->cparams.ecn,
430			   !!nla_get_u32(tb[TCA_FQ_CODEL_ECN]));
431
432	if (quantum)
433		WRITE_ONCE(q->quantum, quantum);
434
435	if (tb[TCA_FQ_CODEL_DROP_BATCH_SIZE])
436		WRITE_ONCE(q->drop_batch_size,
437			   max(1U, nla_get_u32(tb[TCA_FQ_CODEL_DROP_BATCH_SIZE])));
438
439	if (tb[TCA_FQ_CODEL_MEMORY_LIMIT])
440		WRITE_ONCE(q->memory_limit,
441			   min(1U << 31, nla_get_u32(tb[TCA_FQ_CODEL_MEMORY_LIMIT])));
442
443	while (sch->q.qlen > sch->limit ||
444	       q->memory_usage > q->memory_limit) {
445		struct sk_buff *skb = qdisc_dequeue_internal(sch, false);
446
447		if (!skb)
448			break;
449
450		dropped_pkts++;
451		dropped_bytes += qdisc_pkt_len(skb);
452		rtnl_kfree_skbs(skb, skb);
453	}
454	qdisc_tree_reduce_backlog(sch, dropped_pkts, dropped_bytes);
455
456	sch_tree_unlock(sch);
457	return 0;
458}
459
460static void fq_codel_destroy(struct Qdisc *sch)
461{
462	struct fq_codel_sched_data *q = qdisc_priv(sch);
463
464	tcf_block_put(q->block);
465	kvfree(q->backlogs);
466	kvfree(q->flows);
467}
468
469static int fq_codel_init(struct Qdisc *sch, struct nlattr *opt,
470			 struct netlink_ext_ack *extack)
471{
472	struct fq_codel_sched_data *q = qdisc_priv(sch);
473	int i;
474	int err;
475
476	sch->limit = 10*1024;
477	q->flows_cnt = 1024;
478	q->memory_limit = 32 << 20; /* 32 MBytes */
479	q->drop_batch_size = 64;
480	q->quantum = psched_mtu(qdisc_dev(sch));
481	INIT_LIST_HEAD(&q->new_flows);
482	INIT_LIST_HEAD(&q->old_flows);
483	codel_params_init(&q->cparams);
484	codel_stats_init(&q->cstats);
485	q->cparams.ecn = true;
486	q->cparams.mtu = psched_mtu(qdisc_dev(sch));
487
488	if (opt) {
489		err = fq_codel_change(sch, opt, extack);
490		if (err)
491			goto init_failure;
492	}
493
494	err = tcf_block_get(&q->block, &q->filter_list, sch, extack);
495	if (err)
496		goto init_failure;
497
498	if (!q->flows) {
499		q->flows = kvcalloc(q->flows_cnt,
500				    sizeof(struct fq_codel_flow),
501				    GFP_KERNEL);
502		if (!q->flows) {
503			err = -ENOMEM;
504			goto init_failure;
505		}
506		q->backlogs = kvcalloc(q->flows_cnt, sizeof(u32), GFP_KERNEL);
507		if (!q->backlogs) {
508			err = -ENOMEM;
509			goto alloc_failure;
510		}
511		for (i = 0; i < q->flows_cnt; i++) {
512			struct fq_codel_flow *flow = q->flows + i;
513
514			INIT_LIST_HEAD(&flow->flowchain);
515			codel_vars_init(&flow->cvars);
516		}
517	}
518	if (sch->limit >= 1)
519		sch->flags |= TCQ_F_CAN_BYPASS;
520	else
521		sch->flags &= ~TCQ_F_CAN_BYPASS;
522
523	sch->flags |= TCQ_F_DEQUEUE_DROPS;
524
525	return 0;
526
527alloc_failure:
528	kvfree(q->flows);
529	q->flows = NULL;
530init_failure:
531	q->flows_cnt = 0;
532	return err;
533}
534
535static int fq_codel_dump(struct Qdisc *sch, struct sk_buff *skb)
536{
537	struct fq_codel_sched_data *q = qdisc_priv(sch);
538	codel_time_t ce_threshold;
539	struct nlattr *opts;
540
541	opts = nla_nest_start_noflag(skb, TCA_OPTIONS);
542	if (opts == NULL)
543		goto nla_put_failure;
544
545	if (nla_put_u32(skb, TCA_FQ_CODEL_TARGET,
546			codel_time_to_us(READ_ONCE(q->cparams.target))) ||
547	    nla_put_u32(skb, TCA_FQ_CODEL_LIMIT,
548			READ_ONCE(sch->limit)) ||
549	    nla_put_u32(skb, TCA_FQ_CODEL_INTERVAL,
550			codel_time_to_us(READ_ONCE(q->cparams.interval))) ||
551	    nla_put_u32(skb, TCA_FQ_CODEL_ECN,
552			READ_ONCE(q->cparams.ecn)) ||
553	    nla_put_u32(skb, TCA_FQ_CODEL_QUANTUM,
554			READ_ONCE(q->quantum)) ||
555	    nla_put_u32(skb, TCA_FQ_CODEL_DROP_BATCH_SIZE,
556			READ_ONCE(q->drop_batch_size)) ||
557	    nla_put_u32(skb, TCA_FQ_CODEL_MEMORY_LIMIT,
558			READ_ONCE(q->memory_limit)) ||
559	    nla_put_u32(skb, TCA_FQ_CODEL_FLOWS,
560			READ_ONCE(q->flows_cnt)))
561		goto nla_put_failure;
562
563	ce_threshold = READ_ONCE(q->cparams.ce_threshold);
564	if (ce_threshold != CODEL_DISABLED_THRESHOLD) {
565		if (nla_put_u32(skb, TCA_FQ_CODEL_CE_THRESHOLD,
566				codel_time_to_us(ce_threshold)))
567			goto nla_put_failure;
568		if (nla_put_u8(skb, TCA_FQ_CODEL_CE_THRESHOLD_SELECTOR,
569			       READ_ONCE(q->cparams.ce_threshold_selector)))
570			goto nla_put_failure;
571		if (nla_put_u8(skb, TCA_FQ_CODEL_CE_THRESHOLD_MASK,
572			       READ_ONCE(q->cparams.ce_threshold_mask)))
573			goto nla_put_failure;
574	}
575
576	return nla_nest_end(skb, opts);
577
578nla_put_failure:
579	return -1;
580}
581
582static int fq_codel_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
583{
584	struct fq_codel_sched_data *q = qdisc_priv(sch);
585	struct tc_fq_codel_xstats st = {
586		.type				= TCA_FQ_CODEL_XSTATS_QDISC,
587	};
588	struct list_head *pos;
589
590	st.qdisc_stats.maxpacket = q->cstats.maxpacket;
591	st.qdisc_stats.drop_overlimit = q->drop_overlimit;
592	st.qdisc_stats.ecn_mark = q->cstats.ecn_mark;
593	st.qdisc_stats.new_flow_count = q->new_flow_count;
594	st.qdisc_stats.ce_mark = q->cstats.ce_mark;
595	st.qdisc_stats.memory_usage  = q->memory_usage;
596	st.qdisc_stats.drop_overmemory = q->drop_overmemory;
597
598	sch_tree_lock(sch);
599	list_for_each(pos, &q->new_flows)
600		st.qdisc_stats.new_flows_len++;
601
602	list_for_each(pos, &q->old_flows)
603		st.qdisc_stats.old_flows_len++;
604	sch_tree_unlock(sch);
605
606	return gnet_stats_copy_app(d, &st, sizeof(st));
607}
608
609static struct Qdisc *fq_codel_leaf(struct Qdisc *sch, unsigned long arg)
610{
611	return NULL;
612}
613
614static unsigned long fq_codel_find(struct Qdisc *sch, u32 classid)
615{
616	return 0;
617}
618
619static unsigned long fq_codel_bind(struct Qdisc *sch, unsigned long parent,
620			      u32 classid)
621{
622	return 0;
623}
624
625static void fq_codel_unbind(struct Qdisc *q, unsigned long cl)
626{
627}
628
629static struct tcf_block *fq_codel_tcf_block(struct Qdisc *sch, unsigned long cl,
630					    struct netlink_ext_ack *extack)
631{
632	struct fq_codel_sched_data *q = qdisc_priv(sch);
633
634	if (cl)
635		return NULL;
636	return q->block;
637}
638
639static int fq_codel_dump_class(struct Qdisc *sch, unsigned long cl,
640			  struct sk_buff *skb, struct tcmsg *tcm)
641{
642	tcm->tcm_handle |= TC_H_MIN(cl);
643	return 0;
644}
645
646static int fq_codel_dump_class_stats(struct Qdisc *sch, unsigned long cl,
647				     struct gnet_dump *d)
648{
649	struct fq_codel_sched_data *q = qdisc_priv(sch);
650	u32 idx = cl - 1;
651	struct gnet_stats_queue qs = { 0 };
652	struct tc_fq_codel_xstats xstats;
653
654	if (idx < q->flows_cnt) {
655		const struct fq_codel_flow *flow = &q->flows[idx];
656		const struct sk_buff *skb;
657
658		memset(&xstats, 0, sizeof(xstats));
659		xstats.type = TCA_FQ_CODEL_XSTATS_CLASS;
660		xstats.class_stats.deficit = flow->deficit;
661		xstats.class_stats.ldelay =
662			codel_time_to_us(flow->cvars.ldelay);
663		xstats.class_stats.count = flow->cvars.count;
664		xstats.class_stats.lastcount = flow->cvars.lastcount;
665		xstats.class_stats.dropping = flow->cvars.dropping;
666		if (flow->cvars.dropping) {
667			codel_tdiff_t delta = flow->cvars.drop_next -
668					      codel_get_time();
669
670			xstats.class_stats.drop_next = (delta >= 0) ?
671				codel_time_to_us(delta) :
672				-codel_time_to_us(-delta);
673		}
674		if (flow->head) {
675			sch_tree_lock(sch);
676			skb = flow->head;
677			while (skb) {
678				qs.qlen++;
679				skb = skb->next;
680			}
681			sch_tree_unlock(sch);
682		}
683		qs.backlog = q->backlogs[idx];
684		qs.drops = 0;
685	}
686	if (gnet_stats_copy_queue(d, NULL, &qs, qs.qlen) < 0)
687		return -1;
688	if (idx < q->flows_cnt)
689		return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
690	return 0;
691}
692
693static void fq_codel_walk(struct Qdisc *sch, struct qdisc_walker *arg)
694{
695	struct fq_codel_sched_data *q = qdisc_priv(sch);
696	unsigned int i;
697
698	if (arg->stop)
699		return;
700
701	for (i = 0; i < q->flows_cnt; i++) {
702		if (list_empty(&q->flows[i].flowchain)) {
703			arg->count++;
704			continue;
705		}
706		if (!tc_qdisc_stats_dump(sch, i + 1, arg))
707			break;
708	}
709}
710
711static const struct Qdisc_class_ops fq_codel_class_ops = {
712	.leaf		=	fq_codel_leaf,
713	.find		=	fq_codel_find,
714	.tcf_block	=	fq_codel_tcf_block,
715	.bind_tcf	=	fq_codel_bind,
716	.unbind_tcf	=	fq_codel_unbind,
717	.dump		=	fq_codel_dump_class,
718	.dump_stats	=	fq_codel_dump_class_stats,
719	.walk		=	fq_codel_walk,
720};
721
722static struct Qdisc_ops fq_codel_qdisc_ops __read_mostly = {
723	.cl_ops		=	&fq_codel_class_ops,
724	.id		=	"fq_codel",
725	.priv_size	=	sizeof(struct fq_codel_sched_data),
726	.enqueue	=	fq_codel_enqueue,
727	.dequeue	=	fq_codel_dequeue,
728	.peek		=	qdisc_peek_dequeued,
729	.init		=	fq_codel_init,
730	.reset		=	fq_codel_reset,
731	.destroy	=	fq_codel_destroy,
732	.change		=	fq_codel_change,
733	.dump		=	fq_codel_dump,
734	.dump_stats =	fq_codel_dump_stats,
735	.owner		=	THIS_MODULE,
736};
737MODULE_ALIAS_NET_SCH("fq_codel");
738
739static int __init fq_codel_module_init(void)
740{
741	return register_qdisc(&fq_codel_qdisc_ops);
742}
743
744static void __exit fq_codel_module_exit(void)
745{
746	unregister_qdisc(&fq_codel_qdisc_ops);
747}
748
749module_init(fq_codel_module_init)
750module_exit(fq_codel_module_exit)
751MODULE_AUTHOR("Eric Dumazet");
752MODULE_LICENSE("GPL");
753MODULE_DESCRIPTION("Fair Queue CoDel discipline");