xref: /openbmc/linux/net/sched/sch_multiq.c (revision b627b4ed) 
1 /*
2  * Copyright (c) 2008, Intel Corporation.
3  *
4  * This program is free software; you can redistribute it and/or modify it
5  * under the terms and conditions of the GNU General Public License,
6  * version 2, as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope it will be useful, but WITHOUT
9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
11  * more details.
12  *
13  * You should have received a copy of the GNU General Public License along with
14  * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
15  * Place - Suite 330, Boston, MA 02111-1307 USA.
16  *
17  * Author: Alexander Duyck <alexander.h.duyck@intel.com>
18  */
19 
20 #include <linux/module.h>
21 #include <linux/types.h>
22 #include <linux/kernel.h>
23 #include <linux/string.h>
24 #include <linux/errno.h>
25 #include <linux/skbuff.h>
26 #include <net/netlink.h>
27 #include <net/pkt_sched.h>
28 
29 
30 struct multiq_sched_data {
31 	u16 bands;
32 	u16 max_bands;
33 	u16 curband;
34 	struct tcf_proto *filter_list;
35 	struct Qdisc **queues;
36 };
37 
38 
39 static struct Qdisc *
40 multiq_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr)
41 {
42 	struct multiq_sched_data *q = qdisc_priv(sch);
43 	u32 band;
44 	struct tcf_result res;
45 	int err;
46 
47 	*qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
48 	err = tc_classify(skb, q->filter_list, &res);
49 #ifdef CONFIG_NET_CLS_ACT
50 	switch (err) {
51 	case TC_ACT_STOLEN:
52 	case TC_ACT_QUEUED:
53 		*qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
54 	case TC_ACT_SHOT:
55 		return NULL;
56 	}
57 #endif
58 	band = skb_get_queue_mapping(skb);
59 
60 	if (band >= q->bands)
61 		return q->queues[0];
62 
63 	return q->queues[band];
64 }
65 
66 static int
67 multiq_enqueue(struct sk_buff *skb, struct Qdisc *sch)
68 {
69 	struct Qdisc *qdisc;
70 	int ret;
71 
72 	qdisc = multiq_classify(skb, sch, &ret);
73 #ifdef CONFIG_NET_CLS_ACT
74 	if (qdisc == NULL) {
75 
76 		if (ret & __NET_XMIT_BYPASS)
77 			sch->qstats.drops++;
78 		kfree_skb(skb);
79 		return ret;
80 	}
81 #endif
82 
83 	ret = qdisc_enqueue(skb, qdisc);
84 	if (ret == NET_XMIT_SUCCESS) {
85 		sch->bstats.bytes += qdisc_pkt_len(skb);
86 		sch->bstats.packets++;
87 		sch->q.qlen++;
88 		return NET_XMIT_SUCCESS;
89 	}
90 	if (net_xmit_drop_count(ret))
91 		sch->qstats.drops++;
92 	return ret;
93 }
94 
95 static struct sk_buff *multiq_dequeue(struct Qdisc *sch)
96 {
97 	struct multiq_sched_data *q = qdisc_priv(sch);
98 	struct Qdisc *qdisc;
99 	struct sk_buff *skb;
100 	int band;
101 
102 	for (band = 0; band < q->bands; band++) {
103 		/* cycle through bands to ensure fairness */
104 		q->curband++;
105 		if (q->curband >= q->bands)
106 			q->curband = 0;
107 
108 		/* Check that target subqueue is available before
109 		 * pulling an skb to avoid head-of-line blocking.
110 		 */
111 		if (!__netif_subqueue_stopped(qdisc_dev(sch), q->curband)) {
112 			qdisc = q->queues[q->curband];
113 			skb = qdisc->dequeue(qdisc);
114 			if (skb) {
115 				sch->q.qlen--;
116 				return skb;
117 			}
118 		}
119 	}
120 	return NULL;
121 
122 }
123 
124 static struct sk_buff *multiq_peek(struct Qdisc *sch)
125 {
126 	struct multiq_sched_data *q = qdisc_priv(sch);
127 	unsigned int curband = q->curband;
128 	struct Qdisc *qdisc;
129 	struct sk_buff *skb;
130 	int band;
131 
132 	for (band = 0; band < q->bands; band++) {
133 		/* cycle through bands to ensure fairness */
134 		curband++;
135 		if (curband >= q->bands)
136 			curband = 0;
137 
138 		/* Check that target subqueue is available before
139 		 * pulling an skb to avoid head-of-line blocking.
140 		 */
141 		if (!__netif_subqueue_stopped(qdisc_dev(sch), curband)) {
142 			qdisc = q->queues[curband];
143 			skb = qdisc->ops->peek(qdisc);
144 			if (skb)
145 				return skb;
146 		}
147 	}
148 	return NULL;
149 
150 }
151 
152 static unsigned int multiq_drop(struct Qdisc *sch)
153 {
154 	struct multiq_sched_data *q = qdisc_priv(sch);
155 	int band;
156 	unsigned int len;
157 	struct Qdisc *qdisc;
158 
159 	for (band = q->bands-1; band >= 0; band--) {
160 		qdisc = q->queues[band];
161 		if (qdisc->ops->drop) {
162 			len = qdisc->ops->drop(qdisc);
163 			if (len != 0) {
164 				sch->q.qlen--;
165 				return len;
166 			}
167 		}
168 	}
169 	return 0;
170 }
171 
172 
173 static void
174 multiq_reset(struct Qdisc *sch)
175 {
176 	u16 band;
177 	struct multiq_sched_data *q = qdisc_priv(sch);
178 
179 	for (band = 0; band < q->bands; band++)
180 		qdisc_reset(q->queues[band]);
181 	sch->q.qlen = 0;
182 	q->curband = 0;
183 }
184 
185 static void
186 multiq_destroy(struct Qdisc *sch)
187 {
188 	int band;
189 	struct multiq_sched_data *q = qdisc_priv(sch);
190 
191 	tcf_destroy_chain(&q->filter_list);
192 	for (band = 0; band < q->bands; band++)
193 		qdisc_destroy(q->queues[band]);
194 
195 	kfree(q->queues);
196 }
197 
198 static int multiq_tune(struct Qdisc *sch, struct nlattr *opt)
199 {
200 	struct multiq_sched_data *q = qdisc_priv(sch);
201 	struct tc_multiq_qopt *qopt;
202 	int i;
203 
204 	if (!netif_is_multiqueue(qdisc_dev(sch)))
205 		return -EOPNOTSUPP;
206 	if (nla_len(opt) < sizeof(*qopt))
207 		return -EINVAL;
208 
209 	qopt = nla_data(opt);
210 
211 	qopt->bands = qdisc_dev(sch)->real_num_tx_queues;
212 
213 	sch_tree_lock(sch);
214 	q->bands = qopt->bands;
215 	for (i = q->bands; i < q->max_bands; i++) {
216 		if (q->queues[i] != &noop_qdisc) {
217 			struct Qdisc *child = q->queues[i];
218 			q->queues[i] = &noop_qdisc;
219 			qdisc_tree_decrease_qlen(child, child->q.qlen);
220 			qdisc_destroy(child);
221 		}
222 	}
223 
224 	sch_tree_unlock(sch);
225 
226 	for (i = 0; i < q->bands; i++) {
227 		if (q->queues[i] == &noop_qdisc) {
228 			struct Qdisc *child, *old;
229 			child = qdisc_create_dflt(qdisc_dev(sch),
230 						  sch->dev_queue,
231 						  &pfifo_qdisc_ops,
232 						  TC_H_MAKE(sch->handle,
233 							    i + 1));
234 			if (child) {
235 				sch_tree_lock(sch);
236 				old = q->queues[i];
237 				q->queues[i] = child;
238 
239 				if (old != &noop_qdisc) {
240 					qdisc_tree_decrease_qlen(old,
241 								 old->q.qlen);
242 					qdisc_destroy(old);
243 				}
244 				sch_tree_unlock(sch);
245 			}
246 		}
247 	}
248 	return 0;
249 }
250 
251 static int multiq_init(struct Qdisc *sch, struct nlattr *opt)
252 {
253 	struct multiq_sched_data *q = qdisc_priv(sch);
254 	int i, err;
255 
256 	q->queues = NULL;
257 
258 	if (opt == NULL)
259 		return -EINVAL;
260 
261 	q->max_bands = qdisc_dev(sch)->num_tx_queues;
262 
263 	q->queues = kcalloc(q->max_bands, sizeof(struct Qdisc *), GFP_KERNEL);
264 	if (!q->queues)
265 		return -ENOBUFS;
266 	for (i = 0; i < q->max_bands; i++)
267 		q->queues[i] = &noop_qdisc;
268 
269 	err = multiq_tune(sch,opt);
270 
271 	if (err)
272 		kfree(q->queues);
273 
274 	return err;
275 }
276 
277 static int multiq_dump(struct Qdisc *sch, struct sk_buff *skb)
278 {
279 	struct multiq_sched_data *q = qdisc_priv(sch);
280 	unsigned char *b = skb_tail_pointer(skb);
281 	struct tc_multiq_qopt opt;
282 
283 	opt.bands = q->bands;
284 	opt.max_bands = q->max_bands;
285 
286 	NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
287 
288 	return skb->len;
289 
290 nla_put_failure:
291 	nlmsg_trim(skb, b);
292 	return -1;
293 }
294 
295 static int multiq_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
296 		      struct Qdisc **old)
297 {
298 	struct multiq_sched_data *q = qdisc_priv(sch);
299 	unsigned long band = arg - 1;
300 
301 	if (band >= q->bands)
302 		return -EINVAL;
303 
304 	if (new == NULL)
305 		new = &noop_qdisc;
306 
307 	sch_tree_lock(sch);
308 	*old = q->queues[band];
309 	q->queues[band] = new;
310 	qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
311 	qdisc_reset(*old);
312 	sch_tree_unlock(sch);
313 
314 	return 0;
315 }
316 
317 static struct Qdisc *
318 multiq_leaf(struct Qdisc *sch, unsigned long arg)
319 {
320 	struct multiq_sched_data *q = qdisc_priv(sch);
321 	unsigned long band = arg - 1;
322 
323 	if (band >= q->bands)
324 		return NULL;
325 
326 	return q->queues[band];
327 }
328 
329 static unsigned long multiq_get(struct Qdisc *sch, u32 classid)
330 {
331 	struct multiq_sched_data *q = qdisc_priv(sch);
332 	unsigned long band = TC_H_MIN(classid);
333 
334 	if (band - 1 >= q->bands)
335 		return 0;
336 	return band;
337 }
338 
339 static unsigned long multiq_bind(struct Qdisc *sch, unsigned long parent,
340 				 u32 classid)
341 {
342 	return multiq_get(sch, classid);
343 }
344 
345 
346 static void multiq_put(struct Qdisc *q, unsigned long cl)
347 {
348 	return;
349 }
350 
351 static int multiq_change(struct Qdisc *sch, u32 handle, u32 parent,
352 			 struct nlattr **tca, unsigned long *arg)
353 {
354 	unsigned long cl = *arg;
355 	struct multiq_sched_data *q = qdisc_priv(sch);
356 
357 	if (cl - 1 > q->bands)
358 		return -ENOENT;
359 	return 0;
360 }
361 
362 static int multiq_delete(struct Qdisc *sch, unsigned long cl)
363 {
364 	struct multiq_sched_data *q = qdisc_priv(sch);
365 	if (cl - 1 > q->bands)
366 		return -ENOENT;
367 	return 0;
368 }
369 
370 
371 static int multiq_dump_class(struct Qdisc *sch, unsigned long cl,
372 			     struct sk_buff *skb, struct tcmsg *tcm)
373 {
374 	struct multiq_sched_data *q = qdisc_priv(sch);
375 
376 	if (cl - 1 > q->bands)
377 		return -ENOENT;
378 	tcm->tcm_handle |= TC_H_MIN(cl);
379 	if (q->queues[cl-1])
380 		tcm->tcm_info = q->queues[cl-1]->handle;
381 	return 0;
382 }
383 
384 static int multiq_dump_class_stats(struct Qdisc *sch, unsigned long cl,
385 				 struct gnet_dump *d)
386 {
387 	struct multiq_sched_data *q = qdisc_priv(sch);
388 	struct Qdisc *cl_q;
389 
390 	cl_q = q->queues[cl - 1];
391 	if (gnet_stats_copy_basic(d, &cl_q->bstats) < 0 ||
392 	    gnet_stats_copy_queue(d, &cl_q->qstats) < 0)
393 		return -1;
394 
395 	return 0;
396 }
397 
398 static void multiq_walk(struct Qdisc *sch, struct qdisc_walker *arg)
399 {
400 	struct multiq_sched_data *q = qdisc_priv(sch);
401 	int band;
402 
403 	if (arg->stop)
404 		return;
405 
406 	for (band = 0; band < q->bands; band++) {
407 		if (arg->count < arg->skip) {
408 			arg->count++;
409 			continue;
410 		}
411 		if (arg->fn(sch, band+1, arg) < 0) {
412 			arg->stop = 1;
413 			break;
414 		}
415 		arg->count++;
416 	}
417 }
418 
419 static struct tcf_proto **multiq_find_tcf(struct Qdisc *sch, unsigned long cl)
420 {
421 	struct multiq_sched_data *q = qdisc_priv(sch);
422 
423 	if (cl)
424 		return NULL;
425 	return &q->filter_list;
426 }
427 
428 static const struct Qdisc_class_ops multiq_class_ops = {
429 	.graft		=	multiq_graft,
430 	.leaf		=	multiq_leaf,
431 	.get		=	multiq_get,
432 	.put		=	multiq_put,
433 	.change		=	multiq_change,
434 	.delete		=	multiq_delete,
435 	.walk		=	multiq_walk,
436 	.tcf_chain	=	multiq_find_tcf,
437 	.bind_tcf	=	multiq_bind,
438 	.unbind_tcf	=	multiq_put,
439 	.dump		=	multiq_dump_class,
440 	.dump_stats	=	multiq_dump_class_stats,
441 };
442 
443 static struct Qdisc_ops multiq_qdisc_ops __read_mostly = {
444 	.next		=	NULL,
445 	.cl_ops		=	&multiq_class_ops,
446 	.id		=	"multiq",
447 	.priv_size	=	sizeof(struct multiq_sched_data),
448 	.enqueue	=	multiq_enqueue,
449 	.dequeue	=	multiq_dequeue,
450 	.peek		=	multiq_peek,
451 	.drop		=	multiq_drop,
452 	.init		=	multiq_init,
453 	.reset		=	multiq_reset,
454 	.destroy	=	multiq_destroy,
455 	.change		=	multiq_tune,
456 	.dump		=	multiq_dump,
457 	.owner		=	THIS_MODULE,
458 };
459 
460 static int __init multiq_module_init(void)
461 {
462 	return register_qdisc(&multiq_qdisc_ops);
463 }
464 
465 static void __exit multiq_module_exit(void)
466 {
467 	unregister_qdisc(&multiq_qdisc_ops);
468 }
469 
470 module_init(multiq_module_init)
471 module_exit(multiq_module_exit)
472 
473 MODULE_LICENSE("GPL");
474