xref: /freebsd/sys/netpfil/ipfw/dn_aqm_pie.c (revision 81e0e7b9e36d6a25b3af6482811318e085537d2f)
1 /*
2  * PIE - Proportional Integral controller Enhanced AQM algorithm.
3  *
4  * $FreeBSD$
5  *
6  * Copyright (C) 2016 Centre for Advanced Internet Architectures,
7  *  Swinburne University of Technology, Melbourne, Australia.
8  * Portions of this code were made possible in part by a gift from
9  *  The Comcast Innovation Fund.
10  * Implemented by Rasool Al-Saadi <ralsaadi@swin.edu.au>
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions and the following disclaimer.
17  * 2. Redistributions in binary form must reproduce the above copyright
18  *    notice, this list of conditions and the following disclaimer in the
19  *    documentation and/or other materials provided with the distribution.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 #include <sys/cdefs.h>
35 #include "opt_inet6.h"
36 
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/malloc.h>
40 #include <sys/mbuf.h>
41 #include <sys/kernel.h>
42 #include <sys/lock.h>
43 #include <sys/module.h>
44 #include <sys/mutex.h>
45 #include <sys/priv.h>
46 #include <sys/proc.h>
47 #include <sys/rwlock.h>
48 #include <sys/socket.h>
49 #include <sys/time.h>
50 #include <sys/sysctl.h>
51 
52 #include <net/if.h>	/* IFNAMSIZ, struct ifaddr, ifq head, lock.h mutex.h */
53 #include <net/netisr.h>
54 #include <net/vnet.h>
55 
56 #include <netinet/in.h>
57 #include <netinet/ip.h>		/* ip_len, ip_off */
58 #include <netinet/ip_var.h>	/* ip_output(), IP_FORWARDING */
59 #include <netinet/ip_fw.h>
60 #include <netinet/ip_dummynet.h>
61 #include <netinet/if_ether.h> /* various ether_* routines */
62 #include <netinet/ip6.h>       /* for ip6_input, ip6_output prototypes */
63 #include <netinet6/ip6_var.h>
64 #include <netpfil/ipfw/dn_heap.h>
65 
66 #ifdef NEW_AQM
67 #include <netpfil/ipfw/ip_fw_private.h>
68 #include <netpfil/ipfw/ip_dn_private.h>
69 #include <netpfil/ipfw/dn_aqm.h>
70 #include <netpfil/ipfw/dn_aqm_pie.h>
71 #include <netpfil/ipfw/dn_sched.h>
72 
73 /* for debugging */
74 #include <sys/syslog.h>
75 
76 static struct dn_aqm pie_desc;
77 
78 /*  PIE defaults
79  * target=15ms, tupdate=15ms, max_burst=150ms,
80  * max_ecnth=0.1, alpha=0.125, beta=1.25,
81  */
82 struct dn_aqm_pie_parms pie_sysctl =
83 	{ 15 * AQM_TIME_1MS,  15 * AQM_TIME_1MS, 150 * AQM_TIME_1MS,
84 	PIE_SCALE/10 , PIE_SCALE * 0.125,  PIE_SCALE * 1.25 ,
85 	PIE_CAPDROP_ENABLED | PIE_DEPRATEEST_ENABLED | PIE_DERAND_ENABLED };
86 
87 static int
88 pie_sysctl_alpha_beta_handler(SYSCTL_HANDLER_ARGS)
89 {
90 	int error;
91 	long  value;
92 
93 	if (!strcmp(oidp->oid_name,"alpha"))
94 		value = pie_sysctl.alpha;
95 	else
96 		value = pie_sysctl.beta;
97 
98 	value = value * 1000 / PIE_SCALE;
99 	error = sysctl_handle_long(oidp, &value, 0, req);
100 	if (error != 0 || req->newptr == NULL)
101 		return (error);
102 	if (value < 1 || value > 7 * PIE_SCALE)
103 		return (EINVAL);
104 	value = (value * PIE_SCALE) / 1000;
105 	if (!strcmp(oidp->oid_name,"alpha"))
106 			pie_sysctl.alpha = value;
107 	else
108 		pie_sysctl.beta = value;
109 	return (0);
110 }
111 
112 static int
113 pie_sysctl_target_tupdate_maxb_handler(SYSCTL_HANDLER_ARGS)
114 {
115 	int error;
116 	long  value;
117 
118 	if (!strcmp(oidp->oid_name,"target"))
119 		value = pie_sysctl.qdelay_ref;
120 	else if (!strcmp(oidp->oid_name,"tupdate"))
121 		value = pie_sysctl.tupdate;
122 	else
123 		value = pie_sysctl.max_burst;
124 
125 	value = value / AQM_TIME_1US;
126 	error = sysctl_handle_long(oidp, &value, 0, req);
127 	if (error != 0 || req->newptr == NULL)
128 		return (error);
129 	if (value < 1 || value > 10 * AQM_TIME_1S)
130 		return (EINVAL);
131 	value = value * AQM_TIME_1US;
132 
133 	if (!strcmp(oidp->oid_name,"target"))
134 		pie_sysctl.qdelay_ref  = value;
135 	else if (!strcmp(oidp->oid_name,"tupdate"))
136 		pie_sysctl.tupdate  = value;
137 	else
138 		pie_sysctl.max_burst = value;
139 	return (0);
140 }
141 
142 static int
143 pie_sysctl_max_ecnth_handler(SYSCTL_HANDLER_ARGS)
144 {
145 	int error;
146 	long  value;
147 
148 	value = pie_sysctl.max_ecnth;
149 	value = value * 1000 / PIE_SCALE;
150 	error = sysctl_handle_long(oidp, &value, 0, req);
151 	if (error != 0 || req->newptr == NULL)
152 		return (error);
153 	if (value < 1 || value > PIE_SCALE)
154 		return (EINVAL);
155 	value = (value * PIE_SCALE) / 1000;
156 	pie_sysctl.max_ecnth = value;
157 	return (0);
158 }
159 
160 /* define PIE sysctl variables */
161 SYSBEGIN(f4)
162 SYSCTL_DECL(_net_inet);
163 SYSCTL_DECL(_net_inet_ip);
164 SYSCTL_DECL(_net_inet_ip_dummynet);
165 static SYSCTL_NODE(_net_inet_ip_dummynet, OID_AUTO, pie,
166     CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
167     "PIE");
168 
169 #ifdef SYSCTL_NODE
170 SYSCTL_PROC(_net_inet_ip_dummynet_pie, OID_AUTO, target,
171     CTLTYPE_LONG | CTLFLAG_RW | CTLFLAG_NEEDGIANT, NULL, 0,
172     pie_sysctl_target_tupdate_maxb_handler, "L",
173     "queue target in microsecond");
174 SYSCTL_PROC(_net_inet_ip_dummynet_pie, OID_AUTO, tupdate,
175     CTLTYPE_LONG | CTLFLAG_RW | CTLFLAG_NEEDGIANT, NULL, 0,
176     pie_sysctl_target_tupdate_maxb_handler, "L",
177     "the frequency of drop probability calculation in microsecond");
178 SYSCTL_PROC(_net_inet_ip_dummynet_pie, OID_AUTO, max_burst,
179     CTLTYPE_LONG | CTLFLAG_RW | CTLFLAG_NEEDGIANT, NULL, 0,
180     pie_sysctl_target_tupdate_maxb_handler, "L",
181     "Burst allowance interval in microsecond");
182 
183 SYSCTL_PROC(_net_inet_ip_dummynet_pie, OID_AUTO, max_ecnth,
184     CTLTYPE_LONG | CTLFLAG_RW | CTLFLAG_NEEDGIANT, NULL, 0,
185     pie_sysctl_max_ecnth_handler, "L",
186     "ECN safeguard threshold scaled by 1000");
187 
188 SYSCTL_PROC(_net_inet_ip_dummynet_pie, OID_AUTO, alpha,
189     CTLTYPE_LONG | CTLFLAG_RW | CTLFLAG_NEEDGIANT, NULL, 0,
190     pie_sysctl_alpha_beta_handler, "L",
191     "PIE alpha scaled by 1000");
192 SYSCTL_PROC(_net_inet_ip_dummynet_pie, OID_AUTO, beta,
193     CTLTYPE_LONG | CTLFLAG_RW | CTLFLAG_NEEDGIANT, NULL, 0,
194     pie_sysctl_alpha_beta_handler, "L",
195     "beta scaled by 1000");
196 #endif
197 
198 /*
199  * Callout function for drop probability calculation
200  * This function is called over tupdate ms and takes pointer of PIE
201  * status variables as an argument
202   */
203 static void
204 calculate_drop_prob(void *x)
205 {
206 	int64_t p, prob, oldprob;
207 	struct dn_aqm_pie_parms *pprms;
208 	struct pie_status *pst = (struct pie_status *) x;
209 	int p_isneg;
210 
211 	pprms = pst->parms;
212 	prob = pst->drop_prob;
213 
214 	/* calculate current qdelay using DRE method.
215 	 * If TS is used and no data in the queue, reset current_qdelay
216 	 * as it stays at last value during dequeue process.
217 	*/
218 	if (pprms->flags & PIE_DEPRATEEST_ENABLED)
219 		pst->current_qdelay = ((uint64_t)pst->pq->ni.len_bytes *
220 			pst->avg_dq_time) >> PIE_DQ_THRESHOLD_BITS;
221 	else
222 		if (!pst->pq->ni.len_bytes)
223 			 pst->current_qdelay = 0;
224 
225 	/* calculate drop probability */
226 	p = (int64_t)pprms->alpha *
227 		((int64_t)pst->current_qdelay - (int64_t)pprms->qdelay_ref);
228 	p +=(int64_t) pprms->beta *
229 		((int64_t)pst->current_qdelay - (int64_t)pst->qdelay_old);
230 
231 	/* take absolute value so right shift result is well defined */
232 	p_isneg = p < 0;
233 	if (p_isneg) {
234 		p = -p;
235 	}
236 
237 	/* We PIE_MAX_PROB shift by 12-bits to increase the division precision */
238 	p *= (PIE_MAX_PROB << 12) / AQM_TIME_1S;
239 
240 	/* auto-tune drop probability */
241 	if (prob < (PIE_MAX_PROB / 1000000)) /* 0.000001 */
242 		p >>= 11 + PIE_FIX_POINT_BITS + 12;
243 	else if (prob < (PIE_MAX_PROB / 100000)) /* 0.00001 */
244 		p >>= 9 + PIE_FIX_POINT_BITS + 12;
245 	else if (prob < (PIE_MAX_PROB / 10000)) /* 0.0001 */
246 		p >>= 7 + PIE_FIX_POINT_BITS + 12;
247 	else if (prob < (PIE_MAX_PROB / 1000)) /* 0.001 */
248 		p >>= 5 + PIE_FIX_POINT_BITS + 12;
249 	else if (prob < (PIE_MAX_PROB / 100)) /* 0.01 */
250 		p >>= 3 + PIE_FIX_POINT_BITS + 12;
251 	else if (prob < (PIE_MAX_PROB / 10)) /* 0.1 */
252 		p >>= 1 + PIE_FIX_POINT_BITS + 12;
253 	else
254 		p >>= PIE_FIX_POINT_BITS + 12;
255 
256 	oldprob = prob;
257 
258 	if (p_isneg) {
259 		prob = prob - p;
260 
261 		/* check for multiplication underflow */
262 		if (prob > oldprob) {
263 			prob= 0;
264 			D("underflow");
265 		}
266 	} else {
267 		/* Cap Drop adjustment */
268 		if ((pprms->flags & PIE_CAPDROP_ENABLED) &&
269 		    prob >= PIE_MAX_PROB / 10 &&
270 		    p > PIE_MAX_PROB / 50 ) {
271 			p = PIE_MAX_PROB / 50;
272 		}
273 
274 		prob = prob + p;
275 
276 		/* check for multiplication overflow */
277 		if (prob<oldprob) {
278 			D("overflow");
279 			prob= PIE_MAX_PROB;
280 		}
281 	}
282 
283 	/*
284 	 * decay the drop probability exponentially
285 	 * and restrict it to range 0 to PIE_MAX_PROB
286 	 */
287 	if (prob < 0) {
288 		prob = 0;
289 	} else {
290 		if (pst->current_qdelay == 0 && pst->qdelay_old == 0) {
291 			/* 0.98 ~= 1- 1/64 */
292 			prob = prob - (prob >> 6);
293 		}
294 
295 		if (prob > PIE_MAX_PROB) {
296 			prob = PIE_MAX_PROB;
297 		}
298 	}
299 
300 	pst->drop_prob = prob;
301 
302 	/* store current queue delay value in old queue delay*/
303 	pst->qdelay_old = pst->current_qdelay;
304 
305 	/* update burst allowance */
306 	if ((pst->sflags & PIE_ACTIVE) && pst->burst_allowance>0) {
307 
308 		if (pst->burst_allowance > pprms->tupdate )
309 			pst->burst_allowance -= pprms->tupdate;
310 		else
311 			pst->burst_allowance = 0;
312 	}
313 
314 	/* reschedule calculate_drop_prob function */
315 	if (pst->sflags & PIE_ACTIVE)
316 		callout_reset_sbt(&pst->aqm_pie_callout,
317 			(uint64_t)pprms->tupdate * SBT_1US, 0, calculate_drop_prob, pst, 0);
318 
319 	mtx_unlock(&pst->lock_mtx);
320 }
321 
322 /*
323  * Extract a packet from the head of queue 'q'
324  * Return a packet or NULL if the queue is empty.
325  * If getts is set, also extract packet's timestamp from mtag.
326  */
327 static struct mbuf *
328 pie_extract_head(struct dn_queue *q, aqm_time_t *pkt_ts, int getts)
329 {
330 	struct m_tag *mtag;
331 	struct mbuf *m;
332 
333 next:	m = q->mq.head;
334 	if (m == NULL)
335 		return m;
336 	q->mq.head = m->m_nextpkt;
337 
338 	/* Update stats */
339 	update_stats(q, -m->m_pkthdr.len, 0);
340 
341 	if (q->ni.length == 0) /* queue is now idle */
342 			q->q_time = V_dn_cfg.curr_time;
343 
344 	if (getts) {
345 		/* extract packet TS*/
346 		mtag = m_tag_locate(m, MTAG_ABI_COMPAT, DN_AQM_MTAG_TS, NULL);
347 		if (mtag == NULL) {
348 			D("PIE timestamp mtag not found!");
349 			*pkt_ts = 0;
350 		} else {
351 			*pkt_ts = *(aqm_time_t *)(mtag + 1);
352 			m_tag_delete(m,mtag);
353 		}
354 	}
355 	if (m->m_pkthdr.rcvif != NULL &&
356 	    __predict_false(m_rcvif_restore(m) == NULL)) {
357 		m_freem(m);
358 		goto next;
359 	}
360 	return m;
361 }
362 
363 /*
364  * Initiate PIE  variable and optionally activate it
365  */
366 __inline static void
367 init_activate_pie(struct pie_status *pst, int resettimer)
368 {
369 	struct dn_aqm_pie_parms *pprms;
370 
371 	mtx_lock(&pst->lock_mtx);
372 	pprms = pst->parms;
373 	pst->drop_prob = 0;
374 	pst->qdelay_old = 0;
375 	pst->burst_allowance = pprms->max_burst;
376 	pst->accu_prob = 0;
377 	pst->dq_count = 0;
378 	pst->avg_dq_time = 0;
379 	pst->sflags = PIE_INMEASUREMENT;
380 	pst->measurement_start = AQM_UNOW;
381 
382 	if (resettimer) {
383 		pst->sflags |= PIE_ACTIVE;
384 		callout_reset_sbt(&pst->aqm_pie_callout,
385 			(uint64_t)pprms->tupdate * SBT_1US,
386 			0, calculate_drop_prob, pst, 0);
387 	}
388 	//DX(2, "PIE Activated");
389 	mtx_unlock(&pst->lock_mtx);
390 }
391 
392 /*
393  * Deactivate PIE and stop probe update callout
394  */
395 __inline static void
396 deactivate_pie(struct pie_status *pst)
397 {
398 	mtx_lock(&pst->lock_mtx);
399 	pst->sflags &= ~(PIE_ACTIVE | PIE_INMEASUREMENT);
400 	callout_stop(&pst->aqm_pie_callout);
401 	//D("PIE Deactivated");
402 	mtx_unlock(&pst->lock_mtx);
403 }
404 
405 /*
406  * Dequeue and return a pcaket from queue 'q' or NULL if 'q' is empty.
407  * Also, caculate depature time or queue delay using timestamp
408  */
409 static struct mbuf *
410 aqm_pie_dequeue(struct dn_queue *q)
411 {
412 	struct mbuf *m;
413 	struct dn_aqm_pie_parms *pprms;
414 	struct pie_status *pst;
415 	aqm_time_t now;
416 	aqm_time_t pkt_ts, dq_time;
417 	int32_t w;
418 
419 	pst  = q->aqm_status;
420 	pprms = pst->parms;
421 
422 	/*we extarct packet ts only when Departure Rate Estimation dis not used*/
423 	m = pie_extract_head(q, &pkt_ts, !(pprms->flags & PIE_DEPRATEEST_ENABLED));
424 
425 	if (!m || !(pst->sflags & PIE_ACTIVE))
426 		return m;
427 
428 	now = AQM_UNOW;
429 	if (pprms->flags & PIE_DEPRATEEST_ENABLED) {
430 		/* calculate average depature time */
431 		if(pst->sflags & PIE_INMEASUREMENT) {
432 			pst->dq_count += m->m_pkthdr.len;
433 
434 			if (pst->dq_count >= PIE_DQ_THRESHOLD) {
435 				dq_time = now - pst->measurement_start;
436 
437 				/*
438 				 * if we don't have old avg dq_time i.e PIE is (re)initialized,
439 				 * don't use weight to calculate new avg_dq_time
440 				 */
441 				if(pst->avg_dq_time == 0)
442 					pst->avg_dq_time = dq_time;
443 				else {
444 					/*
445 					 * weight = PIE_DQ_THRESHOLD/2^6, but we scaled
446 					 * weight by 2^8. Thus, scaled
447 					 * weight = PIE_DQ_THRESHOLD /2^8
448 					 * */
449 					w = PIE_DQ_THRESHOLD >> 8;
450 					pst->avg_dq_time = (dq_time* w
451 						+ (pst->avg_dq_time * ((1L << 8) - w))) >> 8;
452 					pst->sflags &= ~PIE_INMEASUREMENT;
453 				}
454 			}
455 		}
456 
457 		/*
458 		 * Start new measurment cycle when the queue has
459 		 *  PIE_DQ_THRESHOLD worth of bytes.
460 		 */
461 		if(!(pst->sflags & PIE_INMEASUREMENT) &&
462 			q->ni.len_bytes >= PIE_DQ_THRESHOLD) {
463 			pst->sflags |= PIE_INMEASUREMENT;
464 			pst->measurement_start = now;
465 			pst->dq_count = 0;
466 		}
467 	}
468 	/* Optionally, use packet timestamp to estimate queue delay */
469 	else
470 		pst->current_qdelay = now - pkt_ts;
471 
472 	return m;
473 }
474 
475 /*
476  * Enqueue a packet in q, subject to space and  PIE queue management policy
477  * (whose parameters are in q->fs).
478  * Update stats for the queue and the scheduler.
479  * Return 0 on success, 1 on drop. The packet is consumed anyways.
480  */
481 static int
482 aqm_pie_enqueue(struct dn_queue *q, struct mbuf* m)
483 {
484 	struct dn_fs *f;
485 	uint64_t len;
486 	uint32_t qlen;
487 	struct pie_status *pst;
488 	struct dn_aqm_pie_parms *pprms;
489 	int t;
490 
491 	len = m->m_pkthdr.len;
492 	pst  = q->aqm_status;
493 	if(!pst) {
494 		DX(2, "PIE queue is not initialized\n");
495 		update_stats(q, 0, 1);
496 		FREE_PKT(m);
497 		return 1;
498 	}
499 
500 	f = &(q->fs->fs);
501 	pprms = pst->parms;
502 	t = ENQUE;
503 
504 	/* get current queue length in bytes or packets*/
505 	qlen = (f->flags & DN_QSIZE_BYTES) ?
506 		q->ni.len_bytes : q->ni.length;
507 
508 	/* check for queue size and drop the tail if exceed queue limit*/
509 	if (qlen >= f->qsize)
510 		t = DROP;
511 	/* drop/mark the packet when PIE is active and burst time elapsed */
512 	else if ((pst->sflags & PIE_ACTIVE) && pst->burst_allowance==0
513 			&& drop_early(pst, q->ni.len_bytes) == DROP) {
514 				/*
515 				 * if drop_prob over ECN threshold, drop the packet
516 				 * otherwise mark and enqueue it.
517 				 */
518 				if ((pprms->flags & PIE_ECN_ENABLED) && pst->drop_prob <
519 					(pprms->max_ecnth << (PIE_PROB_BITS - PIE_FIX_POINT_BITS))
520 					&& ecn_mark(m))
521 					t = ENQUE;
522 				else
523 					t = DROP;
524 	}
525 
526 	/* Turn PIE on when 1/3 of the queue is full */
527 	if (!(pst->sflags & PIE_ACTIVE) && qlen >= pst->one_third_q_size) {
528 		init_activate_pie(pst, 1);
529 	}
530 
531 	/*  Reset burst tolerance and optinally turn PIE off*/
532 	if ((pst->sflags & PIE_ACTIVE) && pst->drop_prob == 0 &&
533 		pst->current_qdelay < (pprms->qdelay_ref >> 1) &&
534 		pst->qdelay_old < (pprms->qdelay_ref >> 1)) {
535 			pst->burst_allowance = pprms->max_burst;
536 			if ((pprms->flags & PIE_ON_OFF_MODE_ENABLED) && qlen<=0)
537 				deactivate_pie(pst);
538 	}
539 
540 	/* Timestamp the packet if Departure Rate Estimation is disabled */
541 	if (t != DROP && !(pprms->flags & PIE_DEPRATEEST_ENABLED)) {
542 		/* Add TS to mbuf as a TAG */
543 		struct m_tag *mtag;
544 		mtag = m_tag_locate(m, MTAG_ABI_COMPAT, DN_AQM_MTAG_TS, NULL);
545 		if (mtag == NULL)
546 			mtag = m_tag_alloc(MTAG_ABI_COMPAT, DN_AQM_MTAG_TS,
547 				sizeof(aqm_time_t), M_NOWAIT);
548 		if (mtag == NULL) {
549 			t = DROP;
550 		} else {
551 			*(aqm_time_t *)(mtag + 1) = AQM_UNOW;
552 			m_tag_prepend(m, mtag);
553 		}
554 	}
555 
556 	if (t != DROP) {
557 		mq_append(&q->mq, m);
558 		update_stats(q, len, 0);
559 		return (0);
560 	} else {
561 		update_stats(q, 0, 1);
562 
563 		/* reset accu_prob after packet drop */
564 		pst->accu_prob = 0;
565 		FREE_PKT(m);
566 		return 1;
567 	}
568 	return 0;
569 }
570 
571 /*
572  * initialize PIE for queue 'q'
573  * First allocate memory for PIE status.
574  */
575 static int
576 aqm_pie_init(struct dn_queue *q)
577 {
578 	struct pie_status *pst;
579 	struct dn_aqm_pie_parms *pprms;
580 	int err = 0;
581 
582 	pprms = q->fs->aqmcfg;
583 
584 	do { /* exit with break when error occurs*/
585 		if (!pprms){
586 			DX(2, "AQM_PIE is not configured");
587 			err = EINVAL;
588 			break;
589 		}
590 
591 		q->aqm_status = malloc(sizeof(struct pie_status),
592 				 M_DUMMYNET, M_NOWAIT | M_ZERO);
593 		if (q->aqm_status == NULL) {
594 			D("cannot allocate PIE private data");
595 			err =  ENOMEM ;
596 			break;
597 		}
598 
599 		pst = q->aqm_status;
600 		dummynet_sched_lock();
601 		/* increase reference count for PIE module */
602 		pie_desc.ref_count++;
603 		dummynet_sched_unlock();
604 
605 		pst->pq = q;
606 		pst->parms = pprms;
607 
608 		/* For speed optimization, we caculate 1/3 queue size once here */
609 		// we can use x/3 = (x >>2) + (x >>4) + (x >>7)
610 		pst->one_third_q_size = q->fs->fs.qsize/3;
611 
612 		mtx_init(&pst->lock_mtx, "mtx_pie", NULL, MTX_DEF);
613 		callout_init_mtx(&pst->aqm_pie_callout, &pst->lock_mtx,
614 			CALLOUT_RETURNUNLOCKED);
615 
616 		pst->current_qdelay = 0;
617 		init_activate_pie(pst, !(pprms->flags & PIE_ON_OFF_MODE_ENABLED));
618 
619 		//DX(2, "aqm_PIE_init");
620 
621 	} while(0);
622 
623 	return err;
624 }
625 
626 /*
627  * Callout function to destroy pie mtx and free PIE status memory
628  */
629 static void
630 pie_callout_cleanup(void *x)
631 {
632 	struct pie_status *pst = (struct pie_status *) x;
633 
634 	mtx_unlock(&pst->lock_mtx);
635 	mtx_destroy(&pst->lock_mtx);
636 	free(x, M_DUMMYNET);
637 	dummynet_sched_lock();
638 	pie_desc.ref_count--;
639 	dummynet_sched_unlock();
640 }
641 
642 /*
643  * Clean up PIE status for queue 'q'
644  * Destroy memory allocated for PIE status.
645  */
646 static int
647 aqm_pie_cleanup(struct dn_queue *q)
648 {
649 
650 	if(!q) {
651 		D("q is null");
652 		return 0;
653 	}
654 	struct pie_status *pst  = q->aqm_status;
655 	if(!pst) {
656 		//D("queue is already cleaned up");
657 		return 0;
658 	}
659 	if(!q->fs || !q->fs->aqmcfg) {
660 		D("fs is null or no cfg");
661 		return 1;
662 	}
663 	if (q->fs->aqmfp && q->fs->aqmfp->type !=DN_AQM_PIE) {
664 		D("Not PIE fs (%d)", q->fs->fs.fs_nr);
665 		return 1;
666 	}
667 
668 	/*
669 	 * Free PIE status allocated memory using pie_callout_cleanup() callout
670 	 * function to avoid any potential race.
671 	 * We reset aqm_pie_callout to call pie_callout_cleanup() in next 1um. This
672 	 * stops the scheduled calculate_drop_prob() callout and call pie_callout_cleanup()
673 	 * which does memory freeing.
674 	 */
675 	mtx_lock(&pst->lock_mtx);
676 	callout_reset_sbt(&pst->aqm_pie_callout,
677 		SBT_1US, 0, pie_callout_cleanup, pst, 0);
678 	q->aqm_status = NULL;
679 	mtx_unlock(&pst->lock_mtx);
680 
681 	return 0;
682 }
683 
684 /*
685  * Config PIE parameters
686  * also allocate memory for PIE configurations
687  */
688 static int
689 aqm_pie_config(struct dn_fsk* fs, struct dn_extra_parms *ep, int len)
690 {
691 	struct dn_aqm_pie_parms *pcfg;
692 
693 	int l = sizeof(struct dn_extra_parms);
694 	if (len < l) {
695 		D("invalid sched parms length got %d need %d", len, l);
696 		return EINVAL;
697 	}
698 	/* we free the old cfg because maybe the orignal allocation
699 	 * was used for diffirent AQM type.
700 	 */
701 	if (fs->aqmcfg) {
702 		free(fs->aqmcfg, M_DUMMYNET);
703 		fs->aqmcfg = NULL;
704 	}
705 
706 	fs->aqmcfg = malloc(sizeof(struct dn_aqm_pie_parms),
707 			 M_DUMMYNET, M_NOWAIT | M_ZERO);
708 	if (fs->aqmcfg== NULL) {
709 		D("cannot allocate PIE configuration parameters");
710 		return ENOMEM;
711 	}
712 
713 	/* par array contains pie configuration as follow
714 	 * 0- qdelay_ref,1- tupdate, 2- max_burst
715 	 * 3- max_ecnth, 4- alpha, 5- beta, 6- flags
716 	 */
717 
718 	/* configure PIE parameters */
719 	pcfg = fs->aqmcfg;
720 
721 	if (ep->par[0] < 0)
722 		pcfg->qdelay_ref = pie_sysctl.qdelay_ref * AQM_TIME_1US;
723 	else
724 		pcfg->qdelay_ref = ep->par[0];
725 	if (ep->par[1] < 0)
726 		pcfg->tupdate = pie_sysctl.tupdate * AQM_TIME_1US;
727 	else
728 		pcfg->tupdate = ep->par[1];
729 	if (ep->par[2] < 0)
730 		pcfg->max_burst = pie_sysctl.max_burst * AQM_TIME_1US;
731 	else
732 		pcfg->max_burst = ep->par[2];
733 	if (ep->par[3] < 0)
734 		pcfg->max_ecnth = pie_sysctl.max_ecnth;
735 	else
736 		pcfg->max_ecnth = ep->par[3];
737 	if (ep->par[4] < 0)
738 		pcfg->alpha = pie_sysctl.alpha;
739 	else
740 		pcfg->alpha = ep->par[4];
741 	if (ep->par[5] < 0)
742 		pcfg->beta = pie_sysctl.beta;
743 	else
744 		pcfg->beta = ep->par[5];
745 	if (ep->par[6] < 0)
746 		pcfg->flags = pie_sysctl.flags;
747 	else
748 		pcfg->flags = ep->par[6];
749 
750 	/* bound PIE configurations */
751 	pcfg->qdelay_ref = BOUND_VAR(pcfg->qdelay_ref, 1, 10 * AQM_TIME_1S);
752 	pcfg->tupdate = BOUND_VAR(pcfg->tupdate, 1, 10 * AQM_TIME_1S);
753 	pcfg->max_burst = BOUND_VAR(pcfg->max_burst, 0, 10 * AQM_TIME_1S);
754 	pcfg->max_ecnth = BOUND_VAR(pcfg->max_ecnth, 0, PIE_SCALE);
755 	pcfg->alpha = BOUND_VAR(pcfg->alpha, 0, 7 * PIE_SCALE);
756 	pcfg->beta = BOUND_VAR(pcfg->beta, 0 , 7 * PIE_SCALE);
757 
758 	pie_desc.cfg_ref_count++;
759 	//D("pie cfg_ref_count=%d", pie_desc.cfg_ref_count);
760 	return 0;
761 }
762 
763 /*
764  * Deconfigure PIE and free memory allocation
765  */
766 static int
767 aqm_pie_deconfig(struct dn_fsk* fs)
768 {
769 	if (fs && fs->aqmcfg) {
770 		free(fs->aqmcfg, M_DUMMYNET);
771 		fs->aqmcfg = NULL;
772 		pie_desc.cfg_ref_count--;
773 	}
774 	return 0;
775 }
776 
777 /*
778  * Retrieve PIE configuration parameters.
779  */
780 static int
781 aqm_pie_getconfig (struct dn_fsk *fs, struct dn_extra_parms * ep)
782 {
783 	struct dn_aqm_pie_parms *pcfg;
784 	if (fs->aqmcfg) {
785 		strlcpy(ep->name, pie_desc.name, sizeof(ep->name));
786 		pcfg = fs->aqmcfg;
787 		ep->par[0] = pcfg->qdelay_ref / AQM_TIME_1US;
788 		ep->par[1] = pcfg->tupdate / AQM_TIME_1US;
789 		ep->par[2] = pcfg->max_burst / AQM_TIME_1US;
790 		ep->par[3] = pcfg->max_ecnth;
791 		ep->par[4] = pcfg->alpha;
792 		ep->par[5] = pcfg->beta;
793 		ep->par[6] = pcfg->flags;
794 
795 		return 0;
796 	}
797 	return 1;
798 }
799 
800 static struct dn_aqm pie_desc = {
801 	_SI( .type = )  DN_AQM_PIE,
802 	_SI( .name = )  "PIE",
803 	_SI( .ref_count = )  0,
804 	_SI( .cfg_ref_count = )  0,
805 	_SI( .enqueue = )  aqm_pie_enqueue,
806 	_SI( .dequeue = )  aqm_pie_dequeue,
807 	_SI( .config = )  aqm_pie_config,
808 	_SI( .deconfig = )  aqm_pie_deconfig,
809 	_SI( .getconfig = )  aqm_pie_getconfig,
810 	_SI( .init = )  aqm_pie_init,
811 	_SI( .cleanup = )  aqm_pie_cleanup,
812 };
813 
814 DECLARE_DNAQM_MODULE(dn_aqm_pie, &pie_desc);
815 #endif
816