xref: /freebsd/sys/netpfil/ipfw/dn_aqm_pie.c (revision 031beb4e239bfce798af17f5fe8dba8bcaf13d99)
1 /*
2  * PIE - Proportional Integral controller Enhanced AQM algorithm.
3  *
4  * Copyright (C) 2016 Centre for Advanced Internet Architectures,
5  *  Swinburne University of Technology, Melbourne, Australia.
6  * Portions of this code were made possible in part by a gift from
7  *  The Comcast Innovation Fund.
8  * Implemented by Rasool Al-Saadi <ralsaadi@swin.edu.au>
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 #include <sys/cdefs.h>
33 #include "opt_inet6.h"
34 
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/malloc.h>
38 #include <sys/mbuf.h>
39 #include <sys/kernel.h>
40 #include <sys/lock.h>
41 #include <sys/module.h>
42 #include <sys/mutex.h>
43 #include <sys/priv.h>
44 #include <sys/proc.h>
45 #include <sys/rwlock.h>
46 #include <sys/socket.h>
47 #include <sys/time.h>
48 #include <sys/sysctl.h>
49 
50 #include <net/if.h>	/* IFNAMSIZ, struct ifaddr, ifq head, lock.h mutex.h */
51 #include <net/netisr.h>
52 #include <net/vnet.h>
53 
54 #include <netinet/in.h>
55 #include <netinet/ip.h>		/* ip_len, ip_off */
56 #include <netinet/ip_var.h>	/* ip_output(), IP_FORWARDING */
57 #include <netinet/ip_fw.h>
58 #include <netinet/ip_dummynet.h>
59 #include <netinet/if_ether.h> /* various ether_* routines */
60 #include <netinet/ip6.h>       /* for ip6_input, ip6_output prototypes */
61 #include <netinet6/ip6_var.h>
62 #include <netpfil/ipfw/dn_heap.h>
63 
64 #ifdef NEW_AQM
65 #include <netpfil/ipfw/ip_fw_private.h>
66 #include <netpfil/ipfw/ip_dn_private.h>
67 #include <netpfil/ipfw/dn_aqm.h>
68 #include <netpfil/ipfw/dn_aqm_pie.h>
69 #include <netpfil/ipfw/dn_sched.h>
70 
71 /* for debugging */
72 #include <sys/syslog.h>
73 
74 static struct dn_aqm pie_desc;
75 
76 /*  PIE defaults
77  * target=15ms, tupdate=15ms, max_burst=150ms,
78  * max_ecnth=0.1, alpha=0.125, beta=1.25,
79  */
80 struct dn_aqm_pie_parms pie_sysctl =
81 	{ 15 * AQM_TIME_1MS,  15 * AQM_TIME_1MS, 150 * AQM_TIME_1MS,
82 	PIE_SCALE/10 , PIE_SCALE * 0.125,  PIE_SCALE * 1.25 ,
83 	PIE_CAPDROP_ENABLED | PIE_DEPRATEEST_ENABLED | PIE_DERAND_ENABLED };
84 
85 static int
86 pie_sysctl_alpha_beta_handler(SYSCTL_HANDLER_ARGS)
87 {
88 	int error;
89 	long  value;
90 
91 	if (!strcmp(oidp->oid_name,"alpha"))
92 		value = pie_sysctl.alpha;
93 	else
94 		value = pie_sysctl.beta;
95 
96 	value = value * 1000 / PIE_SCALE;
97 	error = sysctl_handle_long(oidp, &value, 0, req);
98 	if (error != 0 || req->newptr == NULL)
99 		return (error);
100 	if (value < 1 || value > 7 * PIE_SCALE)
101 		return (EINVAL);
102 	value = (value * PIE_SCALE) / 1000;
103 	if (!strcmp(oidp->oid_name,"alpha"))
104 			pie_sysctl.alpha = value;
105 	else
106 		pie_sysctl.beta = value;
107 	return (0);
108 }
109 
110 static int
111 pie_sysctl_target_tupdate_maxb_handler(SYSCTL_HANDLER_ARGS)
112 {
113 	int error;
114 	long  value;
115 
116 	if (!strcmp(oidp->oid_name,"target"))
117 		value = pie_sysctl.qdelay_ref;
118 	else if (!strcmp(oidp->oid_name,"tupdate"))
119 		value = pie_sysctl.tupdate;
120 	else
121 		value = pie_sysctl.max_burst;
122 
123 	value = value / AQM_TIME_1US;
124 	error = sysctl_handle_long(oidp, &value, 0, req);
125 	if (error != 0 || req->newptr == NULL)
126 		return (error);
127 	if (value < 1 || value > 10 * AQM_TIME_1S)
128 		return (EINVAL);
129 	value = value * AQM_TIME_1US;
130 
131 	if (!strcmp(oidp->oid_name,"target"))
132 		pie_sysctl.qdelay_ref  = value;
133 	else if (!strcmp(oidp->oid_name,"tupdate"))
134 		pie_sysctl.tupdate  = value;
135 	else
136 		pie_sysctl.max_burst = value;
137 	return (0);
138 }
139 
140 static int
141 pie_sysctl_max_ecnth_handler(SYSCTL_HANDLER_ARGS)
142 {
143 	int error;
144 	long  value;
145 
146 	value = pie_sysctl.max_ecnth;
147 	value = value * 1000 / PIE_SCALE;
148 	error = sysctl_handle_long(oidp, &value, 0, req);
149 	if (error != 0 || req->newptr == NULL)
150 		return (error);
151 	if (value < 1 || value > PIE_SCALE)
152 		return (EINVAL);
153 	value = (value * PIE_SCALE) / 1000;
154 	pie_sysctl.max_ecnth = value;
155 	return (0);
156 }
157 
158 /* define PIE sysctl variables */
159 SYSBEGIN(f4)
160 SYSCTL_DECL(_net_inet);
161 SYSCTL_DECL(_net_inet_ip);
162 SYSCTL_DECL(_net_inet_ip_dummynet);
163 static SYSCTL_NODE(_net_inet_ip_dummynet, OID_AUTO, pie,
164     CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
165     "PIE");
166 
167 #ifdef SYSCTL_NODE
168 SYSCTL_PROC(_net_inet_ip_dummynet_pie, OID_AUTO, target,
169     CTLTYPE_LONG | CTLFLAG_RW | CTLFLAG_NEEDGIANT, NULL, 0,
170     pie_sysctl_target_tupdate_maxb_handler, "L",
171     "queue target in microsecond");
172 SYSCTL_PROC(_net_inet_ip_dummynet_pie, OID_AUTO, tupdate,
173     CTLTYPE_LONG | CTLFLAG_RW | CTLFLAG_NEEDGIANT, NULL, 0,
174     pie_sysctl_target_tupdate_maxb_handler, "L",
175     "the frequency of drop probability calculation in microsecond");
176 SYSCTL_PROC(_net_inet_ip_dummynet_pie, OID_AUTO, max_burst,
177     CTLTYPE_LONG | CTLFLAG_RW | CTLFLAG_NEEDGIANT, NULL, 0,
178     pie_sysctl_target_tupdate_maxb_handler, "L",
179     "Burst allowance interval in microsecond");
180 
181 SYSCTL_PROC(_net_inet_ip_dummynet_pie, OID_AUTO, max_ecnth,
182     CTLTYPE_LONG | CTLFLAG_RW | CTLFLAG_NEEDGIANT, NULL, 0,
183     pie_sysctl_max_ecnth_handler, "L",
184     "ECN safeguard threshold scaled by 1000");
185 
186 SYSCTL_PROC(_net_inet_ip_dummynet_pie, OID_AUTO, alpha,
187     CTLTYPE_LONG | CTLFLAG_RW | CTLFLAG_NEEDGIANT, NULL, 0,
188     pie_sysctl_alpha_beta_handler, "L",
189     "PIE alpha scaled by 1000");
190 SYSCTL_PROC(_net_inet_ip_dummynet_pie, OID_AUTO, beta,
191     CTLTYPE_LONG | CTLFLAG_RW | CTLFLAG_NEEDGIANT, NULL, 0,
192     pie_sysctl_alpha_beta_handler, "L",
193     "beta scaled by 1000");
194 #endif
195 
196 /*
197  * Callout function for drop probability calculation
198  * This function is called over tupdate ms and takes pointer of PIE
199  * status variables as an argument
200   */
201 static void
202 calculate_drop_prob(void *x)
203 {
204 	int64_t p, prob, oldprob;
205 	struct dn_aqm_pie_parms *pprms;
206 	struct pie_status *pst = (struct pie_status *) x;
207 	int p_isneg;
208 
209 	pprms = pst->parms;
210 	prob = pst->drop_prob;
211 
212 	/* calculate current qdelay using DRE method.
213 	 * If TS is used and no data in the queue, reset current_qdelay
214 	 * as it stays at last value during dequeue process.
215 	*/
216 	if (pprms->flags & PIE_DEPRATEEST_ENABLED)
217 		pst->current_qdelay = ((uint64_t)pst->pq->ni.len_bytes *
218 			pst->avg_dq_time) >> PIE_DQ_THRESHOLD_BITS;
219 	else
220 		if (!pst->pq->ni.len_bytes)
221 			 pst->current_qdelay = 0;
222 
223 	/* calculate drop probability */
224 	p = (int64_t)pprms->alpha *
225 		((int64_t)pst->current_qdelay - (int64_t)pprms->qdelay_ref);
226 	p +=(int64_t) pprms->beta *
227 		((int64_t)pst->current_qdelay - (int64_t)pst->qdelay_old);
228 
229 	/* take absolute value so right shift result is well defined */
230 	p_isneg = p < 0;
231 	if (p_isneg) {
232 		p = -p;
233 	}
234 
235 	/* We PIE_MAX_PROB shift by 12-bits to increase the division precision */
236 	p *= (PIE_MAX_PROB << 12) / AQM_TIME_1S;
237 
238 	/* auto-tune drop probability */
239 	if (prob < (PIE_MAX_PROB / 1000000)) /* 0.000001 */
240 		p >>= 11 + PIE_FIX_POINT_BITS + 12;
241 	else if (prob < (PIE_MAX_PROB / 100000)) /* 0.00001 */
242 		p >>= 9 + PIE_FIX_POINT_BITS + 12;
243 	else if (prob < (PIE_MAX_PROB / 10000)) /* 0.0001 */
244 		p >>= 7 + PIE_FIX_POINT_BITS + 12;
245 	else if (prob < (PIE_MAX_PROB / 1000)) /* 0.001 */
246 		p >>= 5 + PIE_FIX_POINT_BITS + 12;
247 	else if (prob < (PIE_MAX_PROB / 100)) /* 0.01 */
248 		p >>= 3 + PIE_FIX_POINT_BITS + 12;
249 	else if (prob < (PIE_MAX_PROB / 10)) /* 0.1 */
250 		p >>= 1 + PIE_FIX_POINT_BITS + 12;
251 	else
252 		p >>= PIE_FIX_POINT_BITS + 12;
253 
254 	oldprob = prob;
255 
256 	if (p_isneg) {
257 		prob = prob - p;
258 
259 		/* check for multiplication underflow */
260 		if (prob > oldprob) {
261 			prob= 0;
262 			D("underflow");
263 		}
264 	} else {
265 		/* Cap Drop adjustment */
266 		if ((pprms->flags & PIE_CAPDROP_ENABLED) &&
267 		    prob >= PIE_MAX_PROB / 10 &&
268 		    p > PIE_MAX_PROB / 50 ) {
269 			p = PIE_MAX_PROB / 50;
270 		}
271 
272 		prob = prob + p;
273 
274 		/* check for multiplication overflow */
275 		if (prob<oldprob) {
276 			D("overflow");
277 			prob= PIE_MAX_PROB;
278 		}
279 	}
280 
281 	/*
282 	 * decay the drop probability exponentially
283 	 * and restrict it to range 0 to PIE_MAX_PROB
284 	 */
285 	if (prob < 0) {
286 		prob = 0;
287 	} else {
288 		if (pst->current_qdelay == 0 && pst->qdelay_old == 0) {
289 			/* 0.98 ~= 1- 1/64 */
290 			prob = prob - (prob >> 6);
291 		}
292 
293 		if (prob > PIE_MAX_PROB) {
294 			prob = PIE_MAX_PROB;
295 		}
296 	}
297 
298 	pst->drop_prob = prob;
299 
300 	/* store current queue delay value in old queue delay*/
301 	pst->qdelay_old = pst->current_qdelay;
302 
303 	/* update burst allowance */
304 	if ((pst->sflags & PIE_ACTIVE) && pst->burst_allowance>0) {
305 
306 		if (pst->burst_allowance > pprms->tupdate )
307 			pst->burst_allowance -= pprms->tupdate;
308 		else
309 			pst->burst_allowance = 0;
310 	}
311 
312 	/* reschedule calculate_drop_prob function */
313 	if (pst->sflags & PIE_ACTIVE)
314 		callout_reset_sbt(&pst->aqm_pie_callout,
315 			(uint64_t)pprms->tupdate * SBT_1US, 0, calculate_drop_prob, pst, 0);
316 
317 	mtx_unlock(&pst->lock_mtx);
318 }
319 
320 /*
321  * Extract a packet from the head of queue 'q'
322  * Return a packet or NULL if the queue is empty.
323  * If getts is set, also extract packet's timestamp from mtag.
324  */
325 static struct mbuf *
326 pie_extract_head(struct dn_queue *q, aqm_time_t *pkt_ts, int getts)
327 {
328 	struct m_tag *mtag;
329 	struct mbuf *m;
330 
331 next:	m = q->mq.head;
332 	if (m == NULL)
333 		return m;
334 	q->mq.head = m->m_nextpkt;
335 
336 	/* Update stats */
337 	update_stats(q, -m->m_pkthdr.len, 0);
338 
339 	if (q->ni.length == 0) /* queue is now idle */
340 			q->q_time = V_dn_cfg.curr_time;
341 
342 	if (getts) {
343 		/* extract packet TS*/
344 		mtag = m_tag_locate(m, MTAG_ABI_COMPAT, DN_AQM_MTAG_TS, NULL);
345 		if (mtag == NULL) {
346 			D("PIE timestamp mtag not found!");
347 			*pkt_ts = 0;
348 		} else {
349 			*pkt_ts = *(aqm_time_t *)(mtag + 1);
350 			m_tag_delete(m,mtag);
351 		}
352 	}
353 	if (m->m_pkthdr.rcvif != NULL &&
354 	    __predict_false(m_rcvif_restore(m) == NULL)) {
355 		m_freem(m);
356 		goto next;
357 	}
358 	return m;
359 }
360 
361 /*
362  * Initiate PIE  variable and optionally activate it
363  */
364 __inline static void
365 init_activate_pie(struct pie_status *pst, int resettimer)
366 {
367 	struct dn_aqm_pie_parms *pprms;
368 
369 	mtx_lock(&pst->lock_mtx);
370 	pprms = pst->parms;
371 	pst->drop_prob = 0;
372 	pst->qdelay_old = 0;
373 	pst->burst_allowance = pprms->max_burst;
374 	pst->accu_prob = 0;
375 	pst->dq_count = 0;
376 	pst->avg_dq_time = 0;
377 	pst->sflags = PIE_INMEASUREMENT;
378 	pst->measurement_start = AQM_UNOW;
379 
380 	if (resettimer) {
381 		pst->sflags |= PIE_ACTIVE;
382 		callout_reset_sbt(&pst->aqm_pie_callout,
383 			(uint64_t)pprms->tupdate * SBT_1US,
384 			0, calculate_drop_prob, pst, 0);
385 	}
386 	//DX(2, "PIE Activated");
387 	mtx_unlock(&pst->lock_mtx);
388 }
389 
390 /*
391  * Deactivate PIE and stop probe update callout
392  */
393 __inline static void
394 deactivate_pie(struct pie_status *pst)
395 {
396 	mtx_lock(&pst->lock_mtx);
397 	pst->sflags &= ~(PIE_ACTIVE | PIE_INMEASUREMENT);
398 	callout_stop(&pst->aqm_pie_callout);
399 	//D("PIE Deactivated");
400 	mtx_unlock(&pst->lock_mtx);
401 }
402 
403 /*
404  * Dequeue and return a pcaket from queue 'q' or NULL if 'q' is empty.
405  * Also, caculate depature time or queue delay using timestamp
406  */
407 static struct mbuf *
408 aqm_pie_dequeue(struct dn_queue *q)
409 {
410 	struct mbuf *m;
411 	struct dn_aqm_pie_parms *pprms;
412 	struct pie_status *pst;
413 	aqm_time_t now;
414 	aqm_time_t pkt_ts, dq_time;
415 	int32_t w;
416 
417 	pst  = q->aqm_status;
418 	pprms = pst->parms;
419 
420 	/*we extarct packet ts only when Departure Rate Estimation dis not used*/
421 	m = pie_extract_head(q, &pkt_ts, !(pprms->flags & PIE_DEPRATEEST_ENABLED));
422 
423 	if (!m || !(pst->sflags & PIE_ACTIVE))
424 		return m;
425 
426 	now = AQM_UNOW;
427 	if (pprms->flags & PIE_DEPRATEEST_ENABLED) {
428 		/* calculate average depature time */
429 		if(pst->sflags & PIE_INMEASUREMENT) {
430 			pst->dq_count += m->m_pkthdr.len;
431 
432 			if (pst->dq_count >= PIE_DQ_THRESHOLD) {
433 				dq_time = now - pst->measurement_start;
434 
435 				/*
436 				 * if we don't have old avg dq_time i.e PIE is (re)initialized,
437 				 * don't use weight to calculate new avg_dq_time
438 				 */
439 				if(pst->avg_dq_time == 0)
440 					pst->avg_dq_time = dq_time;
441 				else {
442 					/*
443 					 * weight = PIE_DQ_THRESHOLD/2^6, but we scaled
444 					 * weight by 2^8. Thus, scaled
445 					 * weight = PIE_DQ_THRESHOLD /2^8
446 					 * */
447 					w = PIE_DQ_THRESHOLD >> 8;
448 					pst->avg_dq_time = (dq_time* w
449 						+ (pst->avg_dq_time * ((1L << 8) - w))) >> 8;
450 					pst->sflags &= ~PIE_INMEASUREMENT;
451 				}
452 			}
453 		}
454 
455 		/*
456 		 * Start new measurement cycle when the queue has
457 		 * PIE_DQ_THRESHOLD worth of bytes.
458 		 */
459 		if(!(pst->sflags & PIE_INMEASUREMENT) &&
460 			q->ni.len_bytes >= PIE_DQ_THRESHOLD) {
461 			pst->sflags |= PIE_INMEASUREMENT;
462 			pst->measurement_start = now;
463 			pst->dq_count = 0;
464 		}
465 	}
466 	/* Optionally, use packet timestamp to estimate queue delay */
467 	else
468 		pst->current_qdelay = now - pkt_ts;
469 
470 	return m;
471 }
472 
473 /*
474  * Enqueue a packet in q, subject to space and  PIE queue management policy
475  * (whose parameters are in q->fs).
476  * Update stats for the queue and the scheduler.
477  * Return 0 on success, 1 on drop. The packet is consumed anyways.
478  */
479 static int
480 aqm_pie_enqueue(struct dn_queue *q, struct mbuf* m)
481 {
482 	struct dn_fs *f;
483 	uint64_t len;
484 	uint32_t qlen;
485 	struct pie_status *pst;
486 	struct dn_aqm_pie_parms *pprms;
487 	int t;
488 
489 	len = m->m_pkthdr.len;
490 	pst  = q->aqm_status;
491 	if(!pst) {
492 		DX(2, "PIE queue is not initialized\n");
493 		update_stats(q, 0, 1);
494 		FREE_PKT(m);
495 		return 1;
496 	}
497 
498 	f = &(q->fs->fs);
499 	pprms = pst->parms;
500 	t = ENQUE;
501 
502 	/* get current queue length in bytes or packets*/
503 	qlen = (f->flags & DN_QSIZE_BYTES) ?
504 		q->ni.len_bytes : q->ni.length;
505 
506 	/* check for queue size and drop the tail if exceed queue limit*/
507 	if (qlen >= f->qsize)
508 		t = DROP;
509 	/* drop/mark the packet when PIE is active and burst time elapsed */
510 	else if ((pst->sflags & PIE_ACTIVE) && pst->burst_allowance==0
511 			&& drop_early(pst, q->ni.len_bytes) == DROP) {
512 				/*
513 				 * if drop_prob over ECN threshold, drop the packet
514 				 * otherwise mark and enqueue it.
515 				 */
516 				if ((pprms->flags & PIE_ECN_ENABLED) && pst->drop_prob <
517 					(pprms->max_ecnth << (PIE_PROB_BITS - PIE_FIX_POINT_BITS))
518 					&& ecn_mark(m))
519 					t = ENQUE;
520 				else
521 					t = DROP;
522 	}
523 
524 	/* Turn PIE on when 1/3 of the queue is full */
525 	if (!(pst->sflags & PIE_ACTIVE) && qlen >= pst->one_third_q_size) {
526 		init_activate_pie(pst, 1);
527 	}
528 
529 	/*  Reset burst tolerance and optinally turn PIE off*/
530 	if ((pst->sflags & PIE_ACTIVE) && pst->drop_prob == 0 &&
531 		pst->current_qdelay < (pprms->qdelay_ref >> 1) &&
532 		pst->qdelay_old < (pprms->qdelay_ref >> 1)) {
533 			pst->burst_allowance = pprms->max_burst;
534 			if ((pprms->flags & PIE_ON_OFF_MODE_ENABLED) && qlen<=0)
535 				deactivate_pie(pst);
536 	}
537 
538 	/* Timestamp the packet if Departure Rate Estimation is disabled */
539 	if (t != DROP && !(pprms->flags & PIE_DEPRATEEST_ENABLED)) {
540 		/* Add TS to mbuf as a TAG */
541 		struct m_tag *mtag;
542 		mtag = m_tag_locate(m, MTAG_ABI_COMPAT, DN_AQM_MTAG_TS, NULL);
543 		if (mtag == NULL)
544 			mtag = m_tag_alloc(MTAG_ABI_COMPAT, DN_AQM_MTAG_TS,
545 				sizeof(aqm_time_t), M_NOWAIT);
546 		if (mtag == NULL) {
547 			t = DROP;
548 		} else {
549 			*(aqm_time_t *)(mtag + 1) = AQM_UNOW;
550 			m_tag_prepend(m, mtag);
551 		}
552 	}
553 
554 	if (t != DROP) {
555 		mq_append(&q->mq, m);
556 		update_stats(q, len, 0);
557 		return (0);
558 	} else {
559 		update_stats(q, 0, 1);
560 
561 		/* reset accu_prob after packet drop */
562 		pst->accu_prob = 0;
563 		FREE_PKT(m);
564 		return 1;
565 	}
566 	return 0;
567 }
568 
569 /*
570  * initialize PIE for queue 'q'
571  * First allocate memory for PIE status.
572  */
573 static int
574 aqm_pie_init(struct dn_queue *q)
575 {
576 	struct pie_status *pst;
577 	struct dn_aqm_pie_parms *pprms;
578 	int err = 0;
579 
580 	pprms = q->fs->aqmcfg;
581 
582 	do { /* exit with break when error occurs*/
583 		if (!pprms){
584 			DX(2, "AQM_PIE is not configured");
585 			err = EINVAL;
586 			break;
587 		}
588 
589 		q->aqm_status = malloc(sizeof(struct pie_status),
590 				 M_DUMMYNET, M_NOWAIT | M_ZERO);
591 		if (q->aqm_status == NULL) {
592 			D("cannot allocate PIE private data");
593 			err =  ENOMEM ;
594 			break;
595 		}
596 
597 		pst = q->aqm_status;
598 		dummynet_sched_lock();
599 		/* increase reference count for PIE module */
600 		pie_desc.ref_count++;
601 		dummynet_sched_unlock();
602 
603 		pst->pq = q;
604 		pst->parms = pprms;
605 
606 		/* For speed optimization, we caculate 1/3 queue size once here */
607 		// we can use x/3 = (x >>2) + (x >>4) + (x >>7)
608 		pst->one_third_q_size = q->fs->fs.qsize/3;
609 
610 		mtx_init(&pst->lock_mtx, "mtx_pie", NULL, MTX_DEF);
611 		callout_init_mtx(&pst->aqm_pie_callout, &pst->lock_mtx,
612 			CALLOUT_RETURNUNLOCKED);
613 
614 		pst->current_qdelay = 0;
615 		init_activate_pie(pst, !(pprms->flags & PIE_ON_OFF_MODE_ENABLED));
616 
617 		//DX(2, "aqm_PIE_init");
618 
619 	} while(0);
620 
621 	return err;
622 }
623 
624 /*
625  * Callout function to destroy pie mtx and free PIE status memory
626  */
627 static void
628 pie_callout_cleanup(void *x)
629 {
630 	struct pie_status *pst = (struct pie_status *) x;
631 
632 	mtx_unlock(&pst->lock_mtx);
633 	mtx_destroy(&pst->lock_mtx);
634 	free(x, M_DUMMYNET);
635 	dummynet_sched_lock();
636 	pie_desc.ref_count--;
637 	dummynet_sched_unlock();
638 }
639 
640 /*
641  * Clean up PIE status for queue 'q'
642  * Destroy memory allocated for PIE status.
643  */
644 static int
645 aqm_pie_cleanup(struct dn_queue *q)
646 {
647 
648 	if(!q) {
649 		D("q is null");
650 		return 0;
651 	}
652 	struct pie_status *pst  = q->aqm_status;
653 	if(!pst) {
654 		//D("queue is already cleaned up");
655 		return 0;
656 	}
657 	if(!q->fs || !q->fs->aqmcfg) {
658 		D("fs is null or no cfg");
659 		return 1;
660 	}
661 	if (q->fs->aqmfp && q->fs->aqmfp->type !=DN_AQM_PIE) {
662 		D("Not PIE fs (%d)", q->fs->fs.fs_nr);
663 		return 1;
664 	}
665 
666 	/*
667 	 * Free PIE status allocated memory using pie_callout_cleanup() callout
668 	 * function to avoid any potential race.
669 	 * We reset aqm_pie_callout to call pie_callout_cleanup() in next 1um. This
670 	 * stops the scheduled calculate_drop_prob() callout and call pie_callout_cleanup()
671 	 * which does memory freeing.
672 	 */
673 	mtx_lock(&pst->lock_mtx);
674 	callout_reset_sbt(&pst->aqm_pie_callout,
675 		SBT_1US, 0, pie_callout_cleanup, pst, 0);
676 	q->aqm_status = NULL;
677 	mtx_unlock(&pst->lock_mtx);
678 
679 	return 0;
680 }
681 
682 /*
683  * Config PIE parameters
684  * also allocate memory for PIE configurations
685  */
686 static int
687 aqm_pie_config(struct dn_fsk* fs, struct dn_extra_parms *ep, int len)
688 {
689 	struct dn_aqm_pie_parms *pcfg;
690 
691 	int l = sizeof(struct dn_extra_parms);
692 	if (len < l) {
693 		D("invalid sched parms length got %d need %d", len, l);
694 		return EINVAL;
695 	}
696 	/* we free the old cfg because maybe the orignal allocation
697 	 * was used for diffirent AQM type.
698 	 */
699 	if (fs->aqmcfg) {
700 		free(fs->aqmcfg, M_DUMMYNET);
701 		fs->aqmcfg = NULL;
702 	}
703 
704 	fs->aqmcfg = malloc(sizeof(struct dn_aqm_pie_parms),
705 			 M_DUMMYNET, M_NOWAIT | M_ZERO);
706 	if (fs->aqmcfg== NULL) {
707 		D("cannot allocate PIE configuration parameters");
708 		return ENOMEM;
709 	}
710 
711 	/* par array contains pie configuration as follow
712 	 * 0- qdelay_ref,1- tupdate, 2- max_burst
713 	 * 3- max_ecnth, 4- alpha, 5- beta, 6- flags
714 	 */
715 
716 	/* configure PIE parameters */
717 	pcfg = fs->aqmcfg;
718 
719 	if (ep->par[0] < 0)
720 		pcfg->qdelay_ref = pie_sysctl.qdelay_ref * AQM_TIME_1US;
721 	else
722 		pcfg->qdelay_ref = ep->par[0];
723 	if (ep->par[1] < 0)
724 		pcfg->tupdate = pie_sysctl.tupdate * AQM_TIME_1US;
725 	else
726 		pcfg->tupdate = ep->par[1];
727 	if (ep->par[2] < 0)
728 		pcfg->max_burst = pie_sysctl.max_burst * AQM_TIME_1US;
729 	else
730 		pcfg->max_burst = ep->par[2];
731 	if (ep->par[3] < 0)
732 		pcfg->max_ecnth = pie_sysctl.max_ecnth;
733 	else
734 		pcfg->max_ecnth = ep->par[3];
735 	if (ep->par[4] < 0)
736 		pcfg->alpha = pie_sysctl.alpha;
737 	else
738 		pcfg->alpha = ep->par[4];
739 	if (ep->par[5] < 0)
740 		pcfg->beta = pie_sysctl.beta;
741 	else
742 		pcfg->beta = ep->par[5];
743 	if (ep->par[6] < 0)
744 		pcfg->flags = pie_sysctl.flags;
745 	else
746 		pcfg->flags = ep->par[6];
747 
748 	/* bound PIE configurations */
749 	pcfg->qdelay_ref = BOUND_VAR(pcfg->qdelay_ref, 1, 10 * AQM_TIME_1S);
750 	pcfg->tupdate = BOUND_VAR(pcfg->tupdate, 1, 10 * AQM_TIME_1S);
751 	pcfg->max_burst = BOUND_VAR(pcfg->max_burst, 0, 10 * AQM_TIME_1S);
752 	pcfg->max_ecnth = BOUND_VAR(pcfg->max_ecnth, 0, PIE_SCALE);
753 	pcfg->alpha = BOUND_VAR(pcfg->alpha, 0, 7 * PIE_SCALE);
754 	pcfg->beta = BOUND_VAR(pcfg->beta, 0 , 7 * PIE_SCALE);
755 
756 	pie_desc.cfg_ref_count++;
757 	//D("pie cfg_ref_count=%d", pie_desc.cfg_ref_count);
758 	return 0;
759 }
760 
761 /*
762  * Deconfigure PIE and free memory allocation
763  */
764 static int
765 aqm_pie_deconfig(struct dn_fsk* fs)
766 {
767 	if (fs && fs->aqmcfg) {
768 		free(fs->aqmcfg, M_DUMMYNET);
769 		fs->aqmcfg = NULL;
770 		pie_desc.cfg_ref_count--;
771 	}
772 	return 0;
773 }
774 
775 /*
776  * Retrieve PIE configuration parameters.
777  */
778 static int
779 aqm_pie_getconfig (struct dn_fsk *fs, struct dn_extra_parms * ep)
780 {
781 	struct dn_aqm_pie_parms *pcfg;
782 	if (fs->aqmcfg) {
783 		strlcpy(ep->name, pie_desc.name, sizeof(ep->name));
784 		pcfg = fs->aqmcfg;
785 		ep->par[0] = pcfg->qdelay_ref / AQM_TIME_1US;
786 		ep->par[1] = pcfg->tupdate / AQM_TIME_1US;
787 		ep->par[2] = pcfg->max_burst / AQM_TIME_1US;
788 		ep->par[3] = pcfg->max_ecnth;
789 		ep->par[4] = pcfg->alpha;
790 		ep->par[5] = pcfg->beta;
791 		ep->par[6] = pcfg->flags;
792 
793 		return 0;
794 	}
795 	return 1;
796 }
797 
798 static struct dn_aqm pie_desc = {
799 	_SI( .type = )  DN_AQM_PIE,
800 	_SI( .name = )  "PIE",
801 	_SI( .ref_count = )  0,
802 	_SI( .cfg_ref_count = )  0,
803 	_SI( .enqueue = )  aqm_pie_enqueue,
804 	_SI( .dequeue = )  aqm_pie_dequeue,
805 	_SI( .config = )  aqm_pie_config,
806 	_SI( .deconfig = )  aqm_pie_deconfig,
807 	_SI( .getconfig = )  aqm_pie_getconfig,
808 	_SI( .init = )  aqm_pie_init,
809 	_SI( .cleanup = )  aqm_pie_cleanup,
810 };
811 
812 DECLARE_DNAQM_MODULE(dn_aqm_pie, &pie_desc);
813 #endif
814