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		__qdisc_drop(skb, to_free);
172	} while (++i < max_packets && len < threshold);
173
174	/* Tell codel to increase its signal strength also */
175	flow->cvars.count += i;
176	q->backlogs[idx] -= len;
177	q->memory_usage -= mem;
178	sch->qstats.drops += i;
179	sch->qstats.backlog -= len;
180	sch->q.qlen -= i;
181	return idx;
182}
183
184static int fq_codel_enqueue(struct sk_buff *skb, struct Qdisc *sch,
185			    struct sk_buff **to_free)
186{
187	struct fq_codel_sched_data *q = qdisc_priv(sch);
188	unsigned int idx, prev_backlog, prev_qlen;
189	struct fq_codel_flow *flow;
190	int ret;
191	unsigned int pkt_len;
192	bool memory_limited;
193
194	idx = fq_codel_classify(skb, sch, &ret);
195	if (idx == 0) {
196		if (ret & __NET_XMIT_BYPASS)
197			qdisc_qstats_drop(sch);
198		__qdisc_drop(skb, to_free);
199		return ret;
200	}
201	idx--;
202
203	codel_set_enqueue_time(skb);
204	flow = &q->flows[idx];
205	flow_queue_add(flow, skb);
206	q->backlogs[idx] += qdisc_pkt_len(skb);
207	qdisc_qstats_backlog_inc(sch, skb);
208
209	if (list_empty(&flow->flowchain)) {
210		list_add_tail(&flow->flowchain, &q->new_flows);
211		q->new_flow_count++;
212		flow->deficit = q->quantum;
213	}
214	get_codel_cb(skb)->mem_usage = skb->truesize;
215	q->memory_usage += get_codel_cb(skb)->mem_usage;
216	memory_limited = q->memory_usage > q->memory_limit;
217	if (++sch->q.qlen <= sch->limit && !memory_limited)
218		return NET_XMIT_SUCCESS;
219
220	prev_backlog = sch->qstats.backlog;
221	prev_qlen = sch->q.qlen;
222
223	/* save this packet length as it might be dropped by fq_codel_drop() */
224	pkt_len = qdisc_pkt_len(skb);
225	/* fq_codel_drop() is quite expensive, as it performs a linear search
226	 * in q->backlogs[] to find a fat flow.
227	 * So instead of dropping a single packet, drop half of its backlog
228	 * with a 64 packets limit to not add a too big cpu spike here.
229	 */
230	ret = fq_codel_drop(sch, q->drop_batch_size, to_free);
231
232	prev_qlen -= sch->q.qlen;
233	prev_backlog -= sch->qstats.backlog;
234	q->drop_overlimit += prev_qlen;
235	if (memory_limited)
236		q->drop_overmemory += prev_qlen;
237
238	/* As we dropped packet(s), better let upper stack know this.
239	 * If we dropped a packet for this flow, return NET_XMIT_CN,
240	 * but in this case, our parents wont increase their backlogs.
241	 */
242	if (ret == idx) {
243		qdisc_tree_reduce_backlog(sch, prev_qlen - 1,
244					  prev_backlog - pkt_len);
245		return NET_XMIT_CN;
246	}
247	qdisc_tree_reduce_backlog(sch, prev_qlen, prev_backlog);
248	return NET_XMIT_SUCCESS;
249}
250
251/* This is the specific function called from codel_dequeue()
252 * to dequeue a packet from queue. Note: backlog is handled in
253 * codel, we dont need to reduce it here.
254 */
255static struct sk_buff *dequeue_func(struct codel_vars *vars, void *ctx)
256{
257	struct Qdisc *sch = ctx;
258	struct fq_codel_sched_data *q = qdisc_priv(sch);
259	struct fq_codel_flow *flow;
260	struct sk_buff *skb = NULL;
261
262	flow = container_of(vars, struct fq_codel_flow, cvars);
263	if (flow->head) {
264		skb = dequeue_head(flow);
265		q->backlogs[flow - q->flows] -= qdisc_pkt_len(skb);
266		q->memory_usage -= get_codel_cb(skb)->mem_usage;
267		sch->q.qlen--;
268		sch->qstats.backlog -= qdisc_pkt_len(skb);
269	}
270	return skb;
271}
272
273static void drop_func(struct sk_buff *skb, void *ctx)
274{
275	struct Qdisc *sch = ctx;
276
277	kfree_skb(skb);
278	qdisc_qstats_drop(sch);
279}
280
281static struct sk_buff *fq_codel_dequeue(struct Qdisc *sch)
282{
283	struct fq_codel_sched_data *q = qdisc_priv(sch);
284	struct sk_buff *skb;
285	struct fq_codel_flow *flow;
286	struct list_head *head;
287
288begin:
289	head = &q->new_flows;
290	if (list_empty(head)) {
291		head = &q->old_flows;
292		if (list_empty(head))
293			return NULL;
294	}
295	flow = list_first_entry(head, struct fq_codel_flow, flowchain);
296
297	if (flow->deficit <= 0) {
298		flow->deficit += q->quantum;
299		list_move_tail(&flow->flowchain, &q->old_flows);
300		goto begin;
301	}
302
303	skb = codel_dequeue(sch, &sch->qstats.backlog, &q->cparams,
304			    &flow->cvars, &q->cstats, qdisc_pkt_len,
305			    codel_get_enqueue_time, drop_func, dequeue_func);
306
307	if (!skb) {
308		/* force a pass through old_flows to prevent starvation */
309		if ((head == &q->new_flows) && !list_empty(&q->old_flows))
310			list_move_tail(&flow->flowchain, &q->old_flows);
311		else
312			list_del_init(&flow->flowchain);
313		goto begin;
314	}
315	qdisc_bstats_update(sch, skb);
316	flow->deficit -= qdisc_pkt_len(skb);
317	/* We cant call qdisc_tree_reduce_backlog() if our qlen is 0,
318	 * or HTB crashes. Defer it for next round.
319	 */
320	if (q->cstats.drop_count && sch->q.qlen) {
321		qdisc_tree_reduce_backlog(sch, q->cstats.drop_count,
322					  q->cstats.drop_len);
323		q->cstats.drop_count = 0;
324		q->cstats.drop_len = 0;
325	}
326	return skb;
327}
328
329static void fq_codel_flow_purge(struct fq_codel_flow *flow)
330{
331	rtnl_kfree_skbs(flow->head, flow->tail);
332	flow->head = NULL;
333}
334
335static void fq_codel_reset(struct Qdisc *sch)
336{
337	struct fq_codel_sched_data *q = qdisc_priv(sch);
338	int i;
339
340	INIT_LIST_HEAD(&q->new_flows);
341	INIT_LIST_HEAD(&q->old_flows);
342	for (i = 0; i < q->flows_cnt; i++) {
343		struct fq_codel_flow *flow = q->flows + i;
344
345		fq_codel_flow_purge(flow);
346		INIT_LIST_HEAD(&flow->flowchain);
347		codel_vars_init(&flow->cvars);
348	}
349	memset(q->backlogs, 0, q->flows_cnt * sizeof(u32));
 
 
350	q->memory_usage = 0;
351}
352
353static const struct nla_policy fq_codel_policy[TCA_FQ_CODEL_MAX + 1] = {
354	[TCA_FQ_CODEL_TARGET]	= { .type = NLA_U32 },
355	[TCA_FQ_CODEL_LIMIT]	= { .type = NLA_U32 },
356	[TCA_FQ_CODEL_INTERVAL]	= { .type = NLA_U32 },
357	[TCA_FQ_CODEL_ECN]	= { .type = NLA_U32 },
358	[TCA_FQ_CODEL_FLOWS]	= { .type = NLA_U32 },
359	[TCA_FQ_CODEL_QUANTUM]	= { .type = NLA_U32 },
360	[TCA_FQ_CODEL_CE_THRESHOLD] = { .type = NLA_U32 },
361	[TCA_FQ_CODEL_DROP_BATCH_SIZE] = { .type = NLA_U32 },
362	[TCA_FQ_CODEL_MEMORY_LIMIT] = { .type = NLA_U32 },
363	[TCA_FQ_CODEL_CE_THRESHOLD_SELECTOR] = { .type = NLA_U8 },
364	[TCA_FQ_CODEL_CE_THRESHOLD_MASK] = { .type = NLA_U8 },
365};
366
367static int fq_codel_change(struct Qdisc *sch, struct nlattr *opt,
368			   struct netlink_ext_ack *extack)
369{
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		q->cparams.target = (target * NSEC_PER_USEC) >> CODEL_SHIFT;
400	}
401
402	if (tb[TCA_FQ_CODEL_CE_THRESHOLD]) {
403		u64 val = nla_get_u32(tb[TCA_FQ_CODEL_CE_THRESHOLD]);
404
405		q->cparams.ce_threshold = (val * NSEC_PER_USEC) >> CODEL_SHIFT;
406	}
407
408	if (tb[TCA_FQ_CODEL_CE_THRESHOLD_SELECTOR])
409		q->cparams.ce_threshold_selector = nla_get_u8(tb[TCA_FQ_CODEL_CE_THRESHOLD_SELECTOR]);
410	if (tb[TCA_FQ_CODEL_CE_THRESHOLD_MASK])
411		q->cparams.ce_threshold_mask = nla_get_u8(tb[TCA_FQ_CODEL_CE_THRESHOLD_MASK]);
412
413	if (tb[TCA_FQ_CODEL_INTERVAL]) {
414		u64 interval = nla_get_u32(tb[TCA_FQ_CODEL_INTERVAL]);
415
416		q->cparams.interval = (interval * NSEC_PER_USEC) >> CODEL_SHIFT;
417	}
418
419	if (tb[TCA_FQ_CODEL_LIMIT])
420		sch->limit = nla_get_u32(tb[TCA_FQ_CODEL_LIMIT]);
421
422	if (tb[TCA_FQ_CODEL_ECN])
423		q->cparams.ecn = !!nla_get_u32(tb[TCA_FQ_CODEL_ECN]);
424
425	if (quantum)
426		q->quantum = quantum;
427
428	if (tb[TCA_FQ_CODEL_DROP_BATCH_SIZE])
429		q->drop_batch_size = max(1U, nla_get_u32(tb[TCA_FQ_CODEL_DROP_BATCH_SIZE]));
430
431	if (tb[TCA_FQ_CODEL_MEMORY_LIMIT])
432		q->memory_limit = min(1U << 31, nla_get_u32(tb[TCA_FQ_CODEL_MEMORY_LIMIT]));
433
434	while (sch->q.qlen > sch->limit ||
435	       q->memory_usage > q->memory_limit) {
436		struct sk_buff *skb = fq_codel_dequeue(sch);
437
438		q->cstats.drop_len += qdisc_pkt_len(skb);
439		rtnl_kfree_skbs(skb, skb);
440		q->cstats.drop_count++;
441	}
442	qdisc_tree_reduce_backlog(sch, q->cstats.drop_count, q->cstats.drop_len);
443	q->cstats.drop_count = 0;
444	q->cstats.drop_len = 0;
445
446	sch_tree_unlock(sch);
447	return 0;
448}
449
450static void fq_codel_destroy(struct Qdisc *sch)
451{
452	struct fq_codel_sched_data *q = qdisc_priv(sch);
453
454	tcf_block_put(q->block);
455	kvfree(q->backlogs);
456	kvfree(q->flows);
457}
458
459static int fq_codel_init(struct Qdisc *sch, struct nlattr *opt,
460			 struct netlink_ext_ack *extack)
461{
462	struct fq_codel_sched_data *q = qdisc_priv(sch);
463	int i;
464	int err;
465
466	sch->limit = 10*1024;
467	q->flows_cnt = 1024;
468	q->memory_limit = 32 << 20; /* 32 MBytes */
469	q->drop_batch_size = 64;
470	q->quantum = psched_mtu(qdisc_dev(sch));
471	INIT_LIST_HEAD(&q->new_flows);
472	INIT_LIST_HEAD(&q->old_flows);
473	codel_params_init(&q->cparams);
474	codel_stats_init(&q->cstats);
475	q->cparams.ecn = true;
476	q->cparams.mtu = psched_mtu(qdisc_dev(sch));
477
478	if (opt) {
479		err = fq_codel_change(sch, opt, extack);
480		if (err)
481			goto init_failure;
482	}
483
484	err = tcf_block_get(&q->block, &q->filter_list, sch, extack);
485	if (err)
486		goto init_failure;
487
488	if (!q->flows) {
489		q->flows = kvcalloc(q->flows_cnt,
490				    sizeof(struct fq_codel_flow),
491				    GFP_KERNEL);
492		if (!q->flows) {
493			err = -ENOMEM;
494			goto init_failure;
495		}
496		q->backlogs = kvcalloc(q->flows_cnt, sizeof(u32), GFP_KERNEL);
497		if (!q->backlogs) {
498			err = -ENOMEM;
499			goto alloc_failure;
500		}
501		for (i = 0; i < q->flows_cnt; i++) {
502			struct fq_codel_flow *flow = q->flows + i;
503
504			INIT_LIST_HEAD(&flow->flowchain);
505			codel_vars_init(&flow->cvars);
506		}
507	}
508	if (sch->limit >= 1)
509		sch->flags |= TCQ_F_CAN_BYPASS;
510	else
511		sch->flags &= ~TCQ_F_CAN_BYPASS;
512	return 0;
513
514alloc_failure:
515	kvfree(q->flows);
516	q->flows = NULL;
517init_failure:
518	q->flows_cnt = 0;
519	return err;
520}
521
522static int fq_codel_dump(struct Qdisc *sch, struct sk_buff *skb)
523{
524	struct fq_codel_sched_data *q = qdisc_priv(sch);
525	struct nlattr *opts;
526
527	opts = nla_nest_start_noflag(skb, TCA_OPTIONS);
528	if (opts == NULL)
529		goto nla_put_failure;
530
531	if (nla_put_u32(skb, TCA_FQ_CODEL_TARGET,
532			codel_time_to_us(q->cparams.target)) ||
533	    nla_put_u32(skb, TCA_FQ_CODEL_LIMIT,
534			sch->limit) ||
535	    nla_put_u32(skb, TCA_FQ_CODEL_INTERVAL,
536			codel_time_to_us(q->cparams.interval)) ||
537	    nla_put_u32(skb, TCA_FQ_CODEL_ECN,
538			q->cparams.ecn) ||
539	    nla_put_u32(skb, TCA_FQ_CODEL_QUANTUM,
540			q->quantum) ||
541	    nla_put_u32(skb, TCA_FQ_CODEL_DROP_BATCH_SIZE,
542			q->drop_batch_size) ||
543	    nla_put_u32(skb, TCA_FQ_CODEL_MEMORY_LIMIT,
544			q->memory_limit) ||
545	    nla_put_u32(skb, TCA_FQ_CODEL_FLOWS,
546			q->flows_cnt))
547		goto nla_put_failure;
548
549	if (q->cparams.ce_threshold != CODEL_DISABLED_THRESHOLD) {
550		if (nla_put_u32(skb, TCA_FQ_CODEL_CE_THRESHOLD,
551				codel_time_to_us(q->cparams.ce_threshold)))
552			goto nla_put_failure;
553		if (nla_put_u8(skb, TCA_FQ_CODEL_CE_THRESHOLD_SELECTOR, q->cparams.ce_threshold_selector))
554			goto nla_put_failure;
555		if (nla_put_u8(skb, TCA_FQ_CODEL_CE_THRESHOLD_MASK, q->cparams.ce_threshold_mask))
556			goto nla_put_failure;
557	}
558
559	return nla_nest_end(skb, opts);
560
561nla_put_failure:
562	return -1;
563}
564
565static int fq_codel_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
566{
567	struct fq_codel_sched_data *q = qdisc_priv(sch);
568	struct tc_fq_codel_xstats st = {
569		.type				= TCA_FQ_CODEL_XSTATS_QDISC,
570	};
571	struct list_head *pos;
572
573	st.qdisc_stats.maxpacket = q->cstats.maxpacket;
574	st.qdisc_stats.drop_overlimit = q->drop_overlimit;
575	st.qdisc_stats.ecn_mark = q->cstats.ecn_mark;
576	st.qdisc_stats.new_flow_count = q->new_flow_count;
577	st.qdisc_stats.ce_mark = q->cstats.ce_mark;
578	st.qdisc_stats.memory_usage  = q->memory_usage;
579	st.qdisc_stats.drop_overmemory = q->drop_overmemory;
580
581	sch_tree_lock(sch);
582	list_for_each(pos, &q->new_flows)
583		st.qdisc_stats.new_flows_len++;
584
585	list_for_each(pos, &q->old_flows)
586		st.qdisc_stats.old_flows_len++;
587	sch_tree_unlock(sch);
588
589	return gnet_stats_copy_app(d, &st, sizeof(st));
590}
591
592static struct Qdisc *fq_codel_leaf(struct Qdisc *sch, unsigned long arg)
593{
594	return NULL;
595}
596
597static unsigned long fq_codel_find(struct Qdisc *sch, u32 classid)
598{
599	return 0;
600}
601
602static unsigned long fq_codel_bind(struct Qdisc *sch, unsigned long parent,
603			      u32 classid)
604{
605	return 0;
606}
607
608static void fq_codel_unbind(struct Qdisc *q, unsigned long cl)
609{
610}
611
612static struct tcf_block *fq_codel_tcf_block(struct Qdisc *sch, unsigned long cl,
613					    struct netlink_ext_ack *extack)
614{
615	struct fq_codel_sched_data *q = qdisc_priv(sch);
616
617	if (cl)
618		return NULL;
619	return q->block;
620}
621
622static int fq_codel_dump_class(struct Qdisc *sch, unsigned long cl,
623			  struct sk_buff *skb, struct tcmsg *tcm)
624{
625	tcm->tcm_handle |= TC_H_MIN(cl);
626	return 0;
627}
628
629static int fq_codel_dump_class_stats(struct Qdisc *sch, unsigned long cl,
630				     struct gnet_dump *d)
631{
632	struct fq_codel_sched_data *q = qdisc_priv(sch);
633	u32 idx = cl - 1;
634	struct gnet_stats_queue qs = { 0 };
635	struct tc_fq_codel_xstats xstats;
636
637	if (idx < q->flows_cnt) {
638		const struct fq_codel_flow *flow = &q->flows[idx];
639		const struct sk_buff *skb;
640
641		memset(&xstats, 0, sizeof(xstats));
642		xstats.type = TCA_FQ_CODEL_XSTATS_CLASS;
643		xstats.class_stats.deficit = flow->deficit;
644		xstats.class_stats.ldelay =
645			codel_time_to_us(flow->cvars.ldelay);
646		xstats.class_stats.count = flow->cvars.count;
647		xstats.class_stats.lastcount = flow->cvars.lastcount;
648		xstats.class_stats.dropping = flow->cvars.dropping;
649		if (flow->cvars.dropping) {
650			codel_tdiff_t delta = flow->cvars.drop_next -
651					      codel_get_time();
652
653			xstats.class_stats.drop_next = (delta >= 0) ?
654				codel_time_to_us(delta) :
655				-codel_time_to_us(-delta);
656		}
657		if (flow->head) {
658			sch_tree_lock(sch);
659			skb = flow->head;
660			while (skb) {
661				qs.qlen++;
662				skb = skb->next;
663			}
664			sch_tree_unlock(sch);
665		}
666		qs.backlog = q->backlogs[idx];
667		qs.drops = 0;
668	}
669	if (gnet_stats_copy_queue(d, NULL, &qs, qs.qlen) < 0)
670		return -1;
671	if (idx < q->flows_cnt)
672		return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
673	return 0;
674}
675
676static void fq_codel_walk(struct Qdisc *sch, struct qdisc_walker *arg)
677{
678	struct fq_codel_sched_data *q = qdisc_priv(sch);
679	unsigned int i;
680
681	if (arg->stop)
682		return;
683
684	for (i = 0; i < q->flows_cnt; i++) {
685		if (list_empty(&q->flows[i].flowchain)) {
 
686			arg->count++;
687			continue;
688		}
689		if (!tc_qdisc_stats_dump(sch, i + 1, arg))
 
690			break;
 
 
691	}
692}
693
694static const struct Qdisc_class_ops fq_codel_class_ops = {
695	.leaf		=	fq_codel_leaf,
696	.find		=	fq_codel_find,
697	.tcf_block	=	fq_codel_tcf_block,
698	.bind_tcf	=	fq_codel_bind,
699	.unbind_tcf	=	fq_codel_unbind,
700	.dump		=	fq_codel_dump_class,
701	.dump_stats	=	fq_codel_dump_class_stats,
702	.walk		=	fq_codel_walk,
703};
704
705static struct Qdisc_ops fq_codel_qdisc_ops __read_mostly = {
706	.cl_ops		=	&fq_codel_class_ops,
707	.id		=	"fq_codel",
708	.priv_size	=	sizeof(struct fq_codel_sched_data),
709	.enqueue	=	fq_codel_enqueue,
710	.dequeue	=	fq_codel_dequeue,
711	.peek		=	qdisc_peek_dequeued,
712	.init		=	fq_codel_init,
713	.reset		=	fq_codel_reset,
714	.destroy	=	fq_codel_destroy,
715	.change		=	fq_codel_change,
716	.dump		=	fq_codel_dump,
717	.dump_stats =	fq_codel_dump_stats,
718	.owner		=	THIS_MODULE,
719};
720
721static int __init fq_codel_module_init(void)
722{
723	return register_qdisc(&fq_codel_qdisc_ops);
724}
725
726static void __exit fq_codel_module_exit(void)
727{
728	unregister_qdisc(&fq_codel_qdisc_ops);
729}
730
731module_init(fq_codel_module_init)
732module_exit(fq_codel_module_exit)
733MODULE_AUTHOR("Eric Dumazet");
734MODULE_LICENSE("GPL");
735MODULE_DESCRIPTION("Fair Queue CoDel discipline");