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TOMOYO Linux Cross Reference
Linux/net/sched/sch_fq.c

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  1 /*
  2  * net/sched/sch_fq.c Fair Queue Packet Scheduler (per flow pacing)
  3  *
  4  *  Copyright (C) 2013-2015 Eric Dumazet <edumazet@google.com>
  5  *
  6  *      This program is free software; you can redistribute it and/or
  7  *      modify it under the terms of the GNU General Public License
  8  *      as published by the Free Software Foundation; either version
  9  *      2 of the License, or (at your option) any later version.
 10  *
 11  *  Meant to be mostly used for locally generated traffic :
 12  *  Fast classification depends on skb->sk being set before reaching us.
 13  *  If not, (router workload), we use rxhash as fallback, with 32 bits wide hash.
 14  *  All packets belonging to a socket are considered as a 'flow'.
 15  *
 16  *  Flows are dynamically allocated and stored in a hash table of RB trees
 17  *  They are also part of one Round Robin 'queues' (new or old flows)
 18  *
 19  *  Burst avoidance (aka pacing) capability :
 20  *
 21  *  Transport (eg TCP) can set in sk->sk_pacing_rate a rate, enqueue a
 22  *  bunch of packets, and this packet scheduler adds delay between
 23  *  packets to respect rate limitation.
 24  *
 25  *  enqueue() :
 26  *   - lookup one RB tree (out of 1024 or more) to find the flow.
 27  *     If non existent flow, create it, add it to the tree.
 28  *     Add skb to the per flow list of skb (fifo).
 29  *   - Use a special fifo for high prio packets
 30  *
 31  *  dequeue() : serves flows in Round Robin
 32  *  Note : When a flow becomes empty, we do not immediately remove it from
 33  *  rb trees, for performance reasons (its expected to send additional packets,
 34  *  or SLAB cache will reuse socket for another flow)
 35  */
 36 
 37 #include <linux/module.h>
 38 #include <linux/types.h>
 39 #include <linux/kernel.h>
 40 #include <linux/jiffies.h>
 41 #include <linux/string.h>
 42 #include <linux/in.h>
 43 #include <linux/errno.h>
 44 #include <linux/init.h>
 45 #include <linux/skbuff.h>
 46 #include <linux/slab.h>
 47 #include <linux/rbtree.h>
 48 #include <linux/hash.h>
 49 #include <linux/prefetch.h>
 50 #include <linux/vmalloc.h>
 51 #include <net/netlink.h>
 52 #include <net/pkt_sched.h>
 53 #include <net/sock.h>
 54 #include <net/tcp_states.h>
 55 #include <net/tcp.h>
 56 
 57 /*
 58  * Per flow structure, dynamically allocated
 59  */
 60 struct fq_flow {
 61         struct sk_buff  *head;          /* list of skbs for this flow : first skb */
 62         union {
 63                 struct sk_buff *tail;   /* last skb in the list */
 64                 unsigned long  age;     /* jiffies when flow was emptied, for gc */
 65         };
 66         struct rb_node  fq_node;        /* anchor in fq_root[] trees */
 67         struct sock     *sk;
 68         int             qlen;           /* number of packets in flow queue */
 69         int             credit;
 70         u32             socket_hash;    /* sk_hash */
 71         struct fq_flow *next;           /* next pointer in RR lists, or &detached */
 72 
 73         struct rb_node  rate_node;      /* anchor in q->delayed tree */
 74         u64             time_next_packet;
 75 };
 76 
 77 struct fq_flow_head {
 78         struct fq_flow *first;
 79         struct fq_flow *last;
 80 };
 81 
 82 struct fq_sched_data {
 83         struct fq_flow_head new_flows;
 84 
 85         struct fq_flow_head old_flows;
 86 
 87         struct rb_root  delayed;        /* for rate limited flows */
 88         u64             time_next_delayed_flow;
 89         unsigned long   unthrottle_latency_ns;
 90 
 91         struct fq_flow  internal;       /* for non classified or high prio packets */
 92         u32             quantum;
 93         u32             initial_quantum;
 94         u32             flow_refill_delay;
 95         u32             flow_max_rate;  /* optional max rate per flow */
 96         u32             flow_plimit;    /* max packets per flow */
 97         u32             orphan_mask;    /* mask for orphaned skb */
 98         u32             low_rate_threshold;
 99         struct rb_root  *fq_root;
100         u8              rate_enable;
101         u8              fq_trees_log;
102 
103         u32             flows;
104         u32             inactive_flows;
105         u32             throttled_flows;
106 
107         u64             stat_gc_flows;
108         u64             stat_internal_packets;
109         u64             stat_tcp_retrans;
110         u64             stat_throttled;
111         u64             stat_flows_plimit;
112         u64             stat_pkts_too_long;
113         u64             stat_allocation_errors;
114         struct qdisc_watchdog watchdog;
115 };
116 
117 /* special value to mark a detached flow (not on old/new list) */
118 static struct fq_flow detached, throttled;
119 
120 static void fq_flow_set_detached(struct fq_flow *f)
121 {
122         f->next = &detached;
123         f->age = jiffies;
124 }
125 
126 static bool fq_flow_is_detached(const struct fq_flow *f)
127 {
128         return f->next == &detached;
129 }
130 
131 static void fq_flow_set_throttled(struct fq_sched_data *q, struct fq_flow *f)
132 {
133         struct rb_node **p = &q->delayed.rb_node, *parent = NULL;
134 
135         while (*p) {
136                 struct fq_flow *aux;
137 
138                 parent = *p;
139                 aux = rb_entry(parent, struct fq_flow, rate_node);
140                 if (f->time_next_packet >= aux->time_next_packet)
141                         p = &parent->rb_right;
142                 else
143                         p = &parent->rb_left;
144         }
145         rb_link_node(&f->rate_node, parent, p);
146         rb_insert_color(&f->rate_node, &q->delayed);
147         q->throttled_flows++;
148         q->stat_throttled++;
149 
150         f->next = &throttled;
151         if (q->time_next_delayed_flow > f->time_next_packet)
152                 q->time_next_delayed_flow = f->time_next_packet;
153 }
154 
155 
156 static struct kmem_cache *fq_flow_cachep __read_mostly;
157 
158 static void fq_flow_add_tail(struct fq_flow_head *head, struct fq_flow *flow)
159 {
160         if (head->first)
161                 head->last->next = flow;
162         else
163                 head->first = flow;
164         head->last = flow;
165         flow->next = NULL;
166 }
167 
168 /* limit number of collected flows per round */
169 #define FQ_GC_MAX 8
170 #define FQ_GC_AGE (3*HZ)
171 
172 static bool fq_gc_candidate(const struct fq_flow *f)
173 {
174         return fq_flow_is_detached(f) &&
175                time_after(jiffies, f->age + FQ_GC_AGE);
176 }
177 
178 static void fq_gc(struct fq_sched_data *q,
179                   struct rb_root *root,
180                   struct sock *sk)
181 {
182         struct fq_flow *f, *tofree[FQ_GC_MAX];
183         struct rb_node **p, *parent;
184         int fcnt = 0;
185 
186         p = &root->rb_node;
187         parent = NULL;
188         while (*p) {
189                 parent = *p;
190 
191                 f = rb_entry(parent, struct fq_flow, fq_node);
192                 if (f->sk == sk)
193                         break;
194 
195                 if (fq_gc_candidate(f)) {
196                         tofree[fcnt++] = f;
197                         if (fcnt == FQ_GC_MAX)
198                                 break;
199                 }
200 
201                 if (f->sk > sk)
202                         p = &parent->rb_right;
203                 else
204                         p = &parent->rb_left;
205         }
206 
207         q->flows -= fcnt;
208         q->inactive_flows -= fcnt;
209         q->stat_gc_flows += fcnt;
210         while (fcnt) {
211                 struct fq_flow *f = tofree[--fcnt];
212 
213                 rb_erase(&f->fq_node, root);
214                 kmem_cache_free(fq_flow_cachep, f);
215         }
216 }
217 
218 static struct fq_flow *fq_classify(struct sk_buff *skb, struct fq_sched_data *q)
219 {
220         struct rb_node **p, *parent;
221         struct sock *sk = skb->sk;
222         struct rb_root *root;
223         struct fq_flow *f;
224 
225         /* warning: no starvation prevention... */
226         if (unlikely((skb->priority & TC_PRIO_MAX) == TC_PRIO_CONTROL))
227                 return &q->internal;
228 
229         /* SYNACK messages are attached to a TCP_NEW_SYN_RECV request socket
230          * or a listener (SYNCOOKIE mode)
231          * 1) request sockets are not full blown,
232          *    they do not contain sk_pacing_rate
233          * 2) They are not part of a 'flow' yet
234          * 3) We do not want to rate limit them (eg SYNFLOOD attack),
235          *    especially if the listener set SO_MAX_PACING_RATE
236          * 4) We pretend they are orphaned
237          */
238         if (!sk || sk_listener(sk)) {
239                 unsigned long hash = skb_get_hash(skb) & q->orphan_mask;
240 
241                 /* By forcing low order bit to 1, we make sure to not
242                  * collide with a local flow (socket pointers are word aligned)
243                  */
244                 sk = (struct sock *)((hash << 1) | 1UL);
245                 skb_orphan(skb);
246         }
247 
248         root = &q->fq_root[hash_ptr(sk, q->fq_trees_log)];
249 
250         if (q->flows >= (2U << q->fq_trees_log) &&
251             q->inactive_flows > q->flows/2)
252                 fq_gc(q, root, sk);
253 
254         p = &root->rb_node;
255         parent = NULL;
256         while (*p) {
257                 parent = *p;
258 
259                 f = rb_entry(parent, struct fq_flow, fq_node);
260                 if (f->sk == sk) {
261                         /* socket might have been reallocated, so check
262                          * if its sk_hash is the same.
263                          * It not, we need to refill credit with
264                          * initial quantum
265                          */
266                         if (unlikely(skb->sk &&
267                                      f->socket_hash != sk->sk_hash)) {
268                                 f->credit = q->initial_quantum;
269                                 f->socket_hash = sk->sk_hash;
270                                 f->time_next_packet = 0ULL;
271                         }
272                         return f;
273                 }
274                 if (f->sk > sk)
275                         p = &parent->rb_right;
276                 else
277                         p = &parent->rb_left;
278         }
279 
280         f = kmem_cache_zalloc(fq_flow_cachep, GFP_ATOMIC | __GFP_NOWARN);
281         if (unlikely(!f)) {
282                 q->stat_allocation_errors++;
283                 return &q->internal;
284         }
285         fq_flow_set_detached(f);
286         f->sk = sk;
287         if (skb->sk)
288                 f->socket_hash = sk->sk_hash;
289         f->credit = q->initial_quantum;
290 
291         rb_link_node(&f->fq_node, parent, p);
292         rb_insert_color(&f->fq_node, root);
293 
294         q->flows++;
295         q->inactive_flows++;
296         return f;
297 }
298 
299 
300 /* remove one skb from head of flow queue */
301 static struct sk_buff *fq_dequeue_head(struct Qdisc *sch, struct fq_flow *flow)
302 {
303         struct sk_buff *skb = flow->head;
304 
305         if (skb) {
306                 flow->head = skb->next;
307                 skb->next = NULL;
308                 flow->qlen--;
309                 qdisc_qstats_backlog_dec(sch, skb);
310                 sch->q.qlen--;
311         }
312         return skb;
313 }
314 
315 /* We might add in the future detection of retransmits
316  * For the time being, just return false
317  */
318 static bool skb_is_retransmit(struct sk_buff *skb)
319 {
320         return false;
321 }
322 
323 /* add skb to flow queue
324  * flow queue is a linked list, kind of FIFO, except for TCP retransmits
325  * We special case tcp retransmits to be transmitted before other packets.
326  * We rely on fact that TCP retransmits are unlikely, so we do not waste
327  * a separate queue or a pointer.
328  * head->  [retrans pkt 1]
329  *         [retrans pkt 2]
330  *         [ normal pkt 1]
331  *         [ normal pkt 2]
332  *         [ normal pkt 3]
333  * tail->  [ normal pkt 4]
334  */
335 static void flow_queue_add(struct fq_flow *flow, struct sk_buff *skb)
336 {
337         struct sk_buff *prev, *head = flow->head;
338 
339         skb->next = NULL;
340         if (!head) {
341                 flow->head = skb;
342                 flow->tail = skb;
343                 return;
344         }
345         if (likely(!skb_is_retransmit(skb))) {
346                 flow->tail->next = skb;
347                 flow->tail = skb;
348                 return;
349         }
350 
351         /* This skb is a tcp retransmit,
352          * find the last retrans packet in the queue
353          */
354         prev = NULL;
355         while (skb_is_retransmit(head)) {
356                 prev = head;
357                 head = head->next;
358                 if (!head)
359                         break;
360         }
361         if (!prev) { /* no rtx packet in queue, become the new head */
362                 skb->next = flow->head;
363                 flow->head = skb;
364         } else {
365                 if (prev == flow->tail)
366                         flow->tail = skb;
367                 else
368                         skb->next = prev->next;
369                 prev->next = skb;
370         }
371 }
372 
373 static int fq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
374                       struct sk_buff **to_free)
375 {
376         struct fq_sched_data *q = qdisc_priv(sch);
377         struct fq_flow *f;
378 
379         if (unlikely(sch->q.qlen >= sch->limit))
380                 return qdisc_drop(skb, sch, to_free);
381 
382         f = fq_classify(skb, q);
383         if (unlikely(f->qlen >= q->flow_plimit && f != &q->internal)) {
384                 q->stat_flows_plimit++;
385                 return qdisc_drop(skb, sch, to_free);
386         }
387 
388         f->qlen++;
389         if (skb_is_retransmit(skb))
390                 q->stat_tcp_retrans++;
391         qdisc_qstats_backlog_inc(sch, skb);
392         if (fq_flow_is_detached(f)) {
393                 struct sock *sk = skb->sk;
394 
395                 fq_flow_add_tail(&q->new_flows, f);
396                 if (time_after(jiffies, f->age + q->flow_refill_delay))
397                         f->credit = max_t(u32, f->credit, q->quantum);
398                 if (sk && q->rate_enable) {
399                         if (unlikely(smp_load_acquire(&sk->sk_pacing_status) !=
400                                      SK_PACING_FQ))
401                                 smp_store_release(&sk->sk_pacing_status,
402                                                   SK_PACING_FQ);
403                 }
404                 q->inactive_flows--;
405         }
406 
407         /* Note: this overwrites f->age */
408         flow_queue_add(f, skb);
409 
410         if (unlikely(f == &q->internal)) {
411                 q->stat_internal_packets++;
412         }
413         sch->q.qlen++;
414 
415         return NET_XMIT_SUCCESS;
416 }
417 
418 static void fq_check_throttled(struct fq_sched_data *q, u64 now)
419 {
420         unsigned long sample;
421         struct rb_node *p;
422 
423         if (q->time_next_delayed_flow > now)
424                 return;
425 
426         /* Update unthrottle latency EWMA.
427          * This is cheap and can help diagnosing timer/latency problems.
428          */
429         sample = (unsigned long)(now - q->time_next_delayed_flow);
430         q->unthrottle_latency_ns -= q->unthrottle_latency_ns >> 3;
431         q->unthrottle_latency_ns += sample >> 3;
432 
433         q->time_next_delayed_flow = ~0ULL;
434         while ((p = rb_first(&q->delayed)) != NULL) {
435                 struct fq_flow *f = rb_entry(p, struct fq_flow, rate_node);
436 
437                 if (f->time_next_packet > now) {
438                         q->time_next_delayed_flow = f->time_next_packet;
439                         break;
440                 }
441                 rb_erase(p, &q->delayed);
442                 q->throttled_flows--;
443                 fq_flow_add_tail(&q->old_flows, f);
444         }
445 }
446 
447 static struct sk_buff *fq_dequeue(struct Qdisc *sch)
448 {
449         struct fq_sched_data *q = qdisc_priv(sch);
450         u64 now = ktime_get_ns();
451         struct fq_flow_head *head;
452         struct sk_buff *skb;
453         struct fq_flow *f;
454         u32 rate, plen;
455 
456         skb = fq_dequeue_head(sch, &q->internal);
457         if (skb)
458                 goto out;
459         fq_check_throttled(q, now);
460 begin:
461         head = &q->new_flows;
462         if (!head->first) {
463                 head = &q->old_flows;
464                 if (!head->first) {
465                         if (q->time_next_delayed_flow != ~0ULL)
466                                 qdisc_watchdog_schedule_ns(&q->watchdog,
467                                                            q->time_next_delayed_flow);
468                         return NULL;
469                 }
470         }
471         f = head->first;
472 
473         if (f->credit <= 0) {
474                 f->credit += q->quantum;
475                 head->first = f->next;
476                 fq_flow_add_tail(&q->old_flows, f);
477                 goto begin;
478         }
479 
480         skb = f->head;
481         if (unlikely(skb && now < f->time_next_packet &&
482                      !skb_is_tcp_pure_ack(skb))) {
483                 head->first = f->next;
484                 fq_flow_set_throttled(q, f);
485                 goto begin;
486         }
487 
488         skb = fq_dequeue_head(sch, f);
489         if (!skb) {
490                 head->first = f->next;
491                 /* force a pass through old_flows to prevent starvation */
492                 if ((head == &q->new_flows) && q->old_flows.first) {
493                         fq_flow_add_tail(&q->old_flows, f);
494                 } else {
495                         fq_flow_set_detached(f);
496                         q->inactive_flows++;
497                 }
498                 goto begin;
499         }
500         prefetch(&skb->end);
501         f->credit -= qdisc_pkt_len(skb);
502 
503         if (!q->rate_enable)
504                 goto out;
505 
506         /* Do not pace locally generated ack packets */
507         if (skb_is_tcp_pure_ack(skb))
508                 goto out;
509 
510         rate = q->flow_max_rate;
511         if (skb->sk)
512                 rate = min(skb->sk->sk_pacing_rate, rate);
513 
514         if (rate <= q->low_rate_threshold) {
515                 f->credit = 0;
516                 plen = qdisc_pkt_len(skb);
517         } else {
518                 plen = max(qdisc_pkt_len(skb), q->quantum);
519                 if (f->credit > 0)
520                         goto out;
521         }
522         if (rate != ~0U) {
523                 u64 len = (u64)plen * NSEC_PER_SEC;
524 
525                 if (likely(rate))
526                         do_div(len, rate);
527                 /* Since socket rate can change later,
528                  * clamp the delay to 1 second.
529                  * Really, providers of too big packets should be fixed !
530                  */
531                 if (unlikely(len > NSEC_PER_SEC)) {
532                         len = NSEC_PER_SEC;
533                         q->stat_pkts_too_long++;
534                 }
535                 /* Account for schedule/timers drifts.
536                  * f->time_next_packet was set when prior packet was sent,
537                  * and current time (@now) can be too late by tens of us.
538                  */
539                 if (f->time_next_packet)
540                         len -= min(len/2, now - f->time_next_packet);
541                 f->time_next_packet = now + len;
542         }
543 out:
544         qdisc_bstats_update(sch, skb);
545         return skb;
546 }
547 
548 static void fq_flow_purge(struct fq_flow *flow)
549 {
550         rtnl_kfree_skbs(flow->head, flow->tail);
551         flow->head = NULL;
552         flow->qlen = 0;
553 }
554 
555 static void fq_reset(struct Qdisc *sch)
556 {
557         struct fq_sched_data *q = qdisc_priv(sch);
558         struct rb_root *root;
559         struct rb_node *p;
560         struct fq_flow *f;
561         unsigned int idx;
562 
563         sch->q.qlen = 0;
564         sch->qstats.backlog = 0;
565 
566         fq_flow_purge(&q->internal);
567 
568         if (!q->fq_root)
569                 return;
570 
571         for (idx = 0; idx < (1U << q->fq_trees_log); idx++) {
572                 root = &q->fq_root[idx];
573                 while ((p = rb_first(root)) != NULL) {
574                         f = rb_entry(p, struct fq_flow, fq_node);
575                         rb_erase(p, root);
576 
577                         fq_flow_purge(f);
578 
579                         kmem_cache_free(fq_flow_cachep, f);
580                 }
581         }
582         q->new_flows.first      = NULL;
583         q->old_flows.first      = NULL;
584         q->delayed              = RB_ROOT;
585         q->flows                = 0;
586         q->inactive_flows       = 0;
587         q->throttled_flows      = 0;
588 }
589 
590 static void fq_rehash(struct fq_sched_data *q,
591                       struct rb_root *old_array, u32 old_log,
592                       struct rb_root *new_array, u32 new_log)
593 {
594         struct rb_node *op, **np, *parent;
595         struct rb_root *oroot, *nroot;
596         struct fq_flow *of, *nf;
597         int fcnt = 0;
598         u32 idx;
599 
600         for (idx = 0; idx < (1U << old_log); idx++) {
601                 oroot = &old_array[idx];
602                 while ((op = rb_first(oroot)) != NULL) {
603                         rb_erase(op, oroot);
604                         of = rb_entry(op, struct fq_flow, fq_node);
605                         if (fq_gc_candidate(of)) {
606                                 fcnt++;
607                                 kmem_cache_free(fq_flow_cachep, of);
608                                 continue;
609                         }
610                         nroot = &new_array[hash_ptr(of->sk, new_log)];
611 
612                         np = &nroot->rb_node;
613                         parent = NULL;
614                         while (*np) {
615                                 parent = *np;
616 
617                                 nf = rb_entry(parent, struct fq_flow, fq_node);
618                                 BUG_ON(nf->sk == of->sk);
619 
620                                 if (nf->sk > of->sk)
621                                         np = &parent->rb_right;
622                                 else
623                                         np = &parent->rb_left;
624                         }
625 
626                         rb_link_node(&of->fq_node, parent, np);
627                         rb_insert_color(&of->fq_node, nroot);
628                 }
629         }
630         q->flows -= fcnt;
631         q->inactive_flows -= fcnt;
632         q->stat_gc_flows += fcnt;
633 }
634 
635 static void fq_free(void *addr)
636 {
637         kvfree(addr);
638 }
639 
640 static int fq_resize(struct Qdisc *sch, u32 log)
641 {
642         struct fq_sched_data *q = qdisc_priv(sch);
643         struct rb_root *array;
644         void *old_fq_root;
645         u32 idx;
646 
647         if (q->fq_root && log == q->fq_trees_log)
648                 return 0;
649 
650         /* If XPS was setup, we can allocate memory on right NUMA node */
651         array = kvmalloc_node(sizeof(struct rb_root) << log, GFP_KERNEL | __GFP_RETRY_MAYFAIL,
652                               netdev_queue_numa_node_read(sch->dev_queue));
653         if (!array)
654                 return -ENOMEM;
655 
656         for (idx = 0; idx < (1U << log); idx++)
657                 array[idx] = RB_ROOT;
658 
659         sch_tree_lock(sch);
660 
661         old_fq_root = q->fq_root;
662         if (old_fq_root)
663                 fq_rehash(q, old_fq_root, q->fq_trees_log, array, log);
664 
665         q->fq_root = array;
666         q->fq_trees_log = log;
667 
668         sch_tree_unlock(sch);
669 
670         fq_free(old_fq_root);
671 
672         return 0;
673 }
674 
675 static const struct nla_policy fq_policy[TCA_FQ_MAX + 1] = {
676         [TCA_FQ_PLIMIT]                 = { .type = NLA_U32 },
677         [TCA_FQ_FLOW_PLIMIT]            = { .type = NLA_U32 },
678         [TCA_FQ_QUANTUM]                = { .type = NLA_U32 },
679         [TCA_FQ_INITIAL_QUANTUM]        = { .type = NLA_U32 },
680         [TCA_FQ_RATE_ENABLE]            = { .type = NLA_U32 },
681         [TCA_FQ_FLOW_DEFAULT_RATE]      = { .type = NLA_U32 },
682         [TCA_FQ_FLOW_MAX_RATE]          = { .type = NLA_U32 },
683         [TCA_FQ_BUCKETS_LOG]            = { .type = NLA_U32 },
684         [TCA_FQ_FLOW_REFILL_DELAY]      = { .type = NLA_U32 },
685         [TCA_FQ_LOW_RATE_THRESHOLD]     = { .type = NLA_U32 },
686 };
687 
688 static int fq_change(struct Qdisc *sch, struct nlattr *opt)
689 {
690         struct fq_sched_data *q = qdisc_priv(sch);
691         struct nlattr *tb[TCA_FQ_MAX + 1];
692         int err, drop_count = 0;
693         unsigned drop_len = 0;
694         u32 fq_log;
695 
696         if (!opt)
697                 return -EINVAL;
698 
699         err = nla_parse_nested(tb, TCA_FQ_MAX, opt, fq_policy, NULL);
700         if (err < 0)
701                 return err;
702 
703         sch_tree_lock(sch);
704 
705         fq_log = q->fq_trees_log;
706 
707         if (tb[TCA_FQ_BUCKETS_LOG]) {
708                 u32 nval = nla_get_u32(tb[TCA_FQ_BUCKETS_LOG]);
709 
710                 if (nval >= 1 && nval <= ilog2(256*1024))
711                         fq_log = nval;
712                 else
713                         err = -EINVAL;
714         }
715         if (tb[TCA_FQ_PLIMIT])
716                 sch->limit = nla_get_u32(tb[TCA_FQ_PLIMIT]);
717 
718         if (tb[TCA_FQ_FLOW_PLIMIT])
719                 q->flow_plimit = nla_get_u32(tb[TCA_FQ_FLOW_PLIMIT]);
720 
721         if (tb[TCA_FQ_QUANTUM]) {
722                 u32 quantum = nla_get_u32(tb[TCA_FQ_QUANTUM]);
723 
724                 if (quantum > 0)
725                         q->quantum = quantum;
726                 else
727                         err = -EINVAL;
728         }
729 
730         if (tb[TCA_FQ_INITIAL_QUANTUM])
731                 q->initial_quantum = nla_get_u32(tb[TCA_FQ_INITIAL_QUANTUM]);
732 
733         if (tb[TCA_FQ_FLOW_DEFAULT_RATE])
734                 pr_warn_ratelimited("sch_fq: defrate %u ignored.\n",
735                                     nla_get_u32(tb[TCA_FQ_FLOW_DEFAULT_RATE]));
736 
737         if (tb[TCA_FQ_FLOW_MAX_RATE])
738                 q->flow_max_rate = nla_get_u32(tb[TCA_FQ_FLOW_MAX_RATE]);
739 
740         if (tb[TCA_FQ_LOW_RATE_THRESHOLD])
741                 q->low_rate_threshold =
742                         nla_get_u32(tb[TCA_FQ_LOW_RATE_THRESHOLD]);
743 
744         if (tb[TCA_FQ_RATE_ENABLE]) {
745                 u32 enable = nla_get_u32(tb[TCA_FQ_RATE_ENABLE]);
746 
747                 if (enable <= 1)
748                         q->rate_enable = enable;
749                 else
750                         err = -EINVAL;
751         }
752 
753         if (tb[TCA_FQ_FLOW_REFILL_DELAY]) {
754                 u32 usecs_delay = nla_get_u32(tb[TCA_FQ_FLOW_REFILL_DELAY]) ;
755 
756                 q->flow_refill_delay = usecs_to_jiffies(usecs_delay);
757         }
758 
759         if (tb[TCA_FQ_ORPHAN_MASK])
760                 q->orphan_mask = nla_get_u32(tb[TCA_FQ_ORPHAN_MASK]);
761 
762         if (!err) {
763                 sch_tree_unlock(sch);
764                 err = fq_resize(sch, fq_log);
765                 sch_tree_lock(sch);
766         }
767         while (sch->q.qlen > sch->limit) {
768                 struct sk_buff *skb = fq_dequeue(sch);
769 
770                 if (!skb)
771                         break;
772                 drop_len += qdisc_pkt_len(skb);
773                 rtnl_kfree_skbs(skb, skb);
774                 drop_count++;
775         }
776         qdisc_tree_reduce_backlog(sch, drop_count, drop_len);
777 
778         sch_tree_unlock(sch);
779         return err;
780 }
781 
782 static void fq_destroy(struct Qdisc *sch)
783 {
784         struct fq_sched_data *q = qdisc_priv(sch);
785 
786         fq_reset(sch);
787         fq_free(q->fq_root);
788         qdisc_watchdog_cancel(&q->watchdog);
789 }
790 
791 static int fq_init(struct Qdisc *sch, struct nlattr *opt)
792 {
793         struct fq_sched_data *q = qdisc_priv(sch);
794         int err;
795 
796         sch->limit              = 10000;
797         q->flow_plimit          = 100;
798         q->quantum              = 2 * psched_mtu(qdisc_dev(sch));
799         q->initial_quantum      = 10 * psched_mtu(qdisc_dev(sch));
800         q->flow_refill_delay    = msecs_to_jiffies(40);
801         q->flow_max_rate        = ~0U;
802         q->time_next_delayed_flow = ~0ULL;
803         q->rate_enable          = 1;
804         q->new_flows.first      = NULL;
805         q->old_flows.first      = NULL;
806         q->delayed              = RB_ROOT;
807         q->fq_root              = NULL;
808         q->fq_trees_log         = ilog2(1024);
809         q->orphan_mask          = 1024 - 1;
810         q->low_rate_threshold   = 550000 / 8;
811         qdisc_watchdog_init(&q->watchdog, sch);
812 
813         if (opt)
814                 err = fq_change(sch, opt);
815         else
816                 err = fq_resize(sch, q->fq_trees_log);
817 
818         return err;
819 }
820 
821 static int fq_dump(struct Qdisc *sch, struct sk_buff *skb)
822 {
823         struct fq_sched_data *q = qdisc_priv(sch);
824         struct nlattr *opts;
825 
826         opts = nla_nest_start(skb, TCA_OPTIONS);
827         if (opts == NULL)
828                 goto nla_put_failure;
829 
830         /* TCA_FQ_FLOW_DEFAULT_RATE is not used anymore */
831 
832         if (nla_put_u32(skb, TCA_FQ_PLIMIT, sch->limit) ||
833             nla_put_u32(skb, TCA_FQ_FLOW_PLIMIT, q->flow_plimit) ||
834             nla_put_u32(skb, TCA_FQ_QUANTUM, q->quantum) ||
835             nla_put_u32(skb, TCA_FQ_INITIAL_QUANTUM, q->initial_quantum) ||
836             nla_put_u32(skb, TCA_FQ_RATE_ENABLE, q->rate_enable) ||
837             nla_put_u32(skb, TCA_FQ_FLOW_MAX_RATE, q->flow_max_rate) ||
838             nla_put_u32(skb, TCA_FQ_FLOW_REFILL_DELAY,
839                         jiffies_to_usecs(q->flow_refill_delay)) ||
840             nla_put_u32(skb, TCA_FQ_ORPHAN_MASK, q->orphan_mask) ||
841             nla_put_u32(skb, TCA_FQ_LOW_RATE_THRESHOLD,
842                         q->low_rate_threshold) ||
843             nla_put_u32(skb, TCA_FQ_BUCKETS_LOG, q->fq_trees_log))
844                 goto nla_put_failure;
845 
846         return nla_nest_end(skb, opts);
847 
848 nla_put_failure:
849         return -1;
850 }
851 
852 static int fq_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
853 {
854         struct fq_sched_data *q = qdisc_priv(sch);
855         struct tc_fq_qd_stats st;
856 
857         sch_tree_lock(sch);
858 
859         st.gc_flows               = q->stat_gc_flows;
860         st.highprio_packets       = q->stat_internal_packets;
861         st.tcp_retrans            = q->stat_tcp_retrans;
862         st.throttled              = q->stat_throttled;
863         st.flows_plimit           = q->stat_flows_plimit;
864         st.pkts_too_long          = q->stat_pkts_too_long;
865         st.allocation_errors      = q->stat_allocation_errors;
866         st.time_next_delayed_flow = q->time_next_delayed_flow - ktime_get_ns();
867         st.flows                  = q->flows;
868         st.inactive_flows         = q->inactive_flows;
869         st.throttled_flows        = q->throttled_flows;
870         st.unthrottle_latency_ns  = min_t(unsigned long,
871                                           q->unthrottle_latency_ns, ~0U);
872         sch_tree_unlock(sch);
873 
874         return gnet_stats_copy_app(d, &st, sizeof(st));
875 }
876 
877 static struct Qdisc_ops fq_qdisc_ops __read_mostly = {
878         .id             =       "fq",
879         .priv_size      =       sizeof(struct fq_sched_data),
880 
881         .enqueue        =       fq_enqueue,
882         .dequeue        =       fq_dequeue,
883         .peek           =       qdisc_peek_dequeued,
884         .init           =       fq_init,
885         .reset          =       fq_reset,
886         .destroy        =       fq_destroy,
887         .change         =       fq_change,
888         .dump           =       fq_dump,
889         .dump_stats     =       fq_dump_stats,
890         .owner          =       THIS_MODULE,
891 };
892 
893 static int __init fq_module_init(void)
894 {
895         int ret;
896 
897         fq_flow_cachep = kmem_cache_create("fq_flow_cache",
898                                            sizeof(struct fq_flow),
899                                            0, 0, NULL);
900         if (!fq_flow_cachep)
901                 return -ENOMEM;
902 
903         ret = register_qdisc(&fq_qdisc_ops);
904         if (ret)
905                 kmem_cache_destroy(fq_flow_cachep);
906         return ret;
907 }
908 
909 static void __exit fq_module_exit(void)
910 {
911         unregister_qdisc(&fq_qdisc_ops);
912         kmem_cache_destroy(fq_flow_cachep);
913 }
914 
915 module_init(fq_module_init)
916 module_exit(fq_module_exit)
917 MODULE_AUTHOR("Eric Dumazet");
918 MODULE_LICENSE("GPL");
919 

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