xref: /openbmc/linux/net/sched/sch_multiq.c (revision b34e08d5)
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, see <http://www.gnu.org/licenses/>.
15  *
16  * Author: Alexander Duyck <alexander.h.duyck@intel.com>
17  */
18 
19 #include <linux/module.h>
20 #include <linux/slab.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->q.qlen++;
86 		return NET_XMIT_SUCCESS;
87 	}
88 	if (net_xmit_drop_count(ret))
89 		sch->qstats.drops++;
90 	return ret;
91 }
92 
93 static struct sk_buff *multiq_dequeue(struct Qdisc *sch)
94 {
95 	struct multiq_sched_data *q = qdisc_priv(sch);
96 	struct Qdisc *qdisc;
97 	struct sk_buff *skb;
98 	int band;
99 
100 	for (band = 0; band < q->bands; band++) {
101 		/* cycle through bands to ensure fairness */
102 		q->curband++;
103 		if (q->curband >= q->bands)
104 			q->curband = 0;
105 
106 		/* Check that target subqueue is available before
107 		 * pulling an skb to avoid head-of-line blocking.
108 		 */
109 		if (!netif_xmit_stopped(
110 		    netdev_get_tx_queue(qdisc_dev(sch), q->curband))) {
111 			qdisc = q->queues[q->curband];
112 			skb = qdisc->dequeue(qdisc);
113 			if (skb) {
114 				qdisc_bstats_update(sch, 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_xmit_stopped(
142 		    netdev_get_tx_queue(qdisc_dev(sch), curband))) {
143 			qdisc = q->queues[curband];
144 			skb = qdisc->ops->peek(qdisc);
145 			if (skb)
146 				return skb;
147 		}
148 	}
149 	return NULL;
150 
151 }
152 
153 static unsigned int multiq_drop(struct Qdisc *sch)
154 {
155 	struct multiq_sched_data *q = qdisc_priv(sch);
156 	int band;
157 	unsigned int len;
158 	struct Qdisc *qdisc;
159 
160 	for (band = q->bands - 1; band >= 0; band--) {
161 		qdisc = q->queues[band];
162 		if (qdisc->ops->drop) {
163 			len = qdisc->ops->drop(qdisc);
164 			if (len != 0) {
165 				sch->q.qlen--;
166 				return len;
167 			}
168 		}
169 	}
170 	return 0;
171 }
172 
173 
174 static void
175 multiq_reset(struct Qdisc *sch)
176 {
177 	u16 band;
178 	struct multiq_sched_data *q = qdisc_priv(sch);
179 
180 	for (band = 0; band < q->bands; band++)
181 		qdisc_reset(q->queues[band]);
182 	sch->q.qlen = 0;
183 	q->curband = 0;
184 }
185 
186 static void
187 multiq_destroy(struct Qdisc *sch)
188 {
189 	int band;
190 	struct multiq_sched_data *q = qdisc_priv(sch);
191 
192 	tcf_destroy_chain(&q->filter_list);
193 	for (band = 0; band < q->bands; band++)
194 		qdisc_destroy(q->queues[band]);
195 
196 	kfree(q->queues);
197 }
198 
199 static int multiq_tune(struct Qdisc *sch, struct nlattr *opt)
200 {
201 	struct multiq_sched_data *q = qdisc_priv(sch);
202 	struct tc_multiq_qopt *qopt;
203 	int i;
204 
205 	if (!netif_is_multiqueue(qdisc_dev(sch)))
206 		return -EOPNOTSUPP;
207 	if (nla_len(opt) < sizeof(*qopt))
208 		return -EINVAL;
209 
210 	qopt = nla_data(opt);
211 
212 	qopt->bands = qdisc_dev(sch)->real_num_tx_queues;
213 
214 	sch_tree_lock(sch);
215 	q->bands = qopt->bands;
216 	for (i = q->bands; i < q->max_bands; i++) {
217 		if (q->queues[i] != &noop_qdisc) {
218 			struct Qdisc *child = q->queues[i];
219 			q->queues[i] = &noop_qdisc;
220 			qdisc_tree_decrease_qlen(child, child->q.qlen);
221 			qdisc_destroy(child);
222 		}
223 	}
224 
225 	sch_tree_unlock(sch);
226 
227 	for (i = 0; i < q->bands; i++) {
228 		if (q->queues[i] == &noop_qdisc) {
229 			struct Qdisc *child, *old;
230 			child = qdisc_create_dflt(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 	if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
287 		goto nla_put_failure;
288 
289 	return skb->len;
290 
291 nla_put_failure:
292 	nlmsg_trim(skb, b);
293 	return -1;
294 }
295 
296 static int multiq_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
297 		      struct Qdisc **old)
298 {
299 	struct multiq_sched_data *q = qdisc_priv(sch);
300 	unsigned long band = arg - 1;
301 
302 	if (new == NULL)
303 		new = &noop_qdisc;
304 
305 	sch_tree_lock(sch);
306 	*old = q->queues[band];
307 	q->queues[band] = new;
308 	qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
309 	qdisc_reset(*old);
310 	sch_tree_unlock(sch);
311 
312 	return 0;
313 }
314 
315 static struct Qdisc *
316 multiq_leaf(struct Qdisc *sch, unsigned long arg)
317 {
318 	struct multiq_sched_data *q = qdisc_priv(sch);
319 	unsigned long band = arg - 1;
320 
321 	return q->queues[band];
322 }
323 
324 static unsigned long multiq_get(struct Qdisc *sch, u32 classid)
325 {
326 	struct multiq_sched_data *q = qdisc_priv(sch);
327 	unsigned long band = TC_H_MIN(classid);
328 
329 	if (band - 1 >= q->bands)
330 		return 0;
331 	return band;
332 }
333 
334 static unsigned long multiq_bind(struct Qdisc *sch, unsigned long parent,
335 				 u32 classid)
336 {
337 	return multiq_get(sch, classid);
338 }
339 
340 
341 static void multiq_put(struct Qdisc *q, unsigned long cl)
342 {
343 }
344 
345 static int multiq_dump_class(struct Qdisc *sch, unsigned long cl,
346 			     struct sk_buff *skb, struct tcmsg *tcm)
347 {
348 	struct multiq_sched_data *q = qdisc_priv(sch);
349 
350 	tcm->tcm_handle |= TC_H_MIN(cl);
351 	tcm->tcm_info = q->queues[cl - 1]->handle;
352 	return 0;
353 }
354 
355 static int multiq_dump_class_stats(struct Qdisc *sch, unsigned long cl,
356 				 struct gnet_dump *d)
357 {
358 	struct multiq_sched_data *q = qdisc_priv(sch);
359 	struct Qdisc *cl_q;
360 
361 	cl_q = q->queues[cl - 1];
362 	cl_q->qstats.qlen = cl_q->q.qlen;
363 	if (gnet_stats_copy_basic(d, &cl_q->bstats) < 0 ||
364 	    gnet_stats_copy_queue(d, &cl_q->qstats) < 0)
365 		return -1;
366 
367 	return 0;
368 }
369 
370 static void multiq_walk(struct Qdisc *sch, struct qdisc_walker *arg)
371 {
372 	struct multiq_sched_data *q = qdisc_priv(sch);
373 	int band;
374 
375 	if (arg->stop)
376 		return;
377 
378 	for (band = 0; band < q->bands; band++) {
379 		if (arg->count < arg->skip) {
380 			arg->count++;
381 			continue;
382 		}
383 		if (arg->fn(sch, band + 1, arg) < 0) {
384 			arg->stop = 1;
385 			break;
386 		}
387 		arg->count++;
388 	}
389 }
390 
391 static struct tcf_proto **multiq_find_tcf(struct Qdisc *sch, unsigned long cl)
392 {
393 	struct multiq_sched_data *q = qdisc_priv(sch);
394 
395 	if (cl)
396 		return NULL;
397 	return &q->filter_list;
398 }
399 
400 static const struct Qdisc_class_ops multiq_class_ops = {
401 	.graft		=	multiq_graft,
402 	.leaf		=	multiq_leaf,
403 	.get		=	multiq_get,
404 	.put		=	multiq_put,
405 	.walk		=	multiq_walk,
406 	.tcf_chain	=	multiq_find_tcf,
407 	.bind_tcf	=	multiq_bind,
408 	.unbind_tcf	=	multiq_put,
409 	.dump		=	multiq_dump_class,
410 	.dump_stats	=	multiq_dump_class_stats,
411 };
412 
413 static struct Qdisc_ops multiq_qdisc_ops __read_mostly = {
414 	.next		=	NULL,
415 	.cl_ops		=	&multiq_class_ops,
416 	.id		=	"multiq",
417 	.priv_size	=	sizeof(struct multiq_sched_data),
418 	.enqueue	=	multiq_enqueue,
419 	.dequeue	=	multiq_dequeue,
420 	.peek		=	multiq_peek,
421 	.drop		=	multiq_drop,
422 	.init		=	multiq_init,
423 	.reset		=	multiq_reset,
424 	.destroy	=	multiq_destroy,
425 	.change		=	multiq_tune,
426 	.dump		=	multiq_dump,
427 	.owner		=	THIS_MODULE,
428 };
429 
430 static int __init multiq_module_init(void)
431 {
432 	return register_qdisc(&multiq_qdisc_ops);
433 }
434 
435 static void __exit multiq_module_exit(void)
436 {
437 	unregister_qdisc(&multiq_qdisc_ops);
438 }
439 
440 module_init(multiq_module_init)
441 module_exit(multiq_module_exit)
442 
443 MODULE_LICENSE("GPL");
444