xref: /openbmc/linux/net/sched/sch_prio.c (revision 82e6fdd6) 
1 /*
2  * net/sched/sch_prio.c	Simple 3-band priority "scheduler".
3  *
4  *		This program is free software; you can redistribute it and/or
5  *		modify it under the terms of the GNU General Public License
6  *		as published by the Free Software Foundation; either version
7  *		2 of the License, or (at your option) any later version.
8  *
9  * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
10  * Fixes:       19990609: J Hadi Salim <hadi@nortelnetworks.com>:
11  *              Init --  EINVAL when opt undefined
12  */
13 
14 #include <linux/module.h>
15 #include <linux/slab.h>
16 #include <linux/types.h>
17 #include <linux/kernel.h>
18 #include <linux/string.h>
19 #include <linux/errno.h>
20 #include <linux/skbuff.h>
21 #include <net/netlink.h>
22 #include <net/pkt_sched.h>
23 #include <net/pkt_cls.h>
24 
25 struct prio_sched_data {
26 	int bands;
27 	struct tcf_proto __rcu *filter_list;
28 	struct tcf_block *block;
29 	u8  prio2band[TC_PRIO_MAX+1];
30 	struct Qdisc *queues[TCQ_PRIO_BANDS];
31 };
32 
33 
34 static struct Qdisc *
35 prio_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr)
36 {
37 	struct prio_sched_data *q = qdisc_priv(sch);
38 	u32 band = skb->priority;
39 	struct tcf_result res;
40 	struct tcf_proto *fl;
41 	int err;
42 
43 	*qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
44 	if (TC_H_MAJ(skb->priority) != sch->handle) {
45 		fl = rcu_dereference_bh(q->filter_list);
46 		err = tcf_classify(skb, fl, &res, false);
47 #ifdef CONFIG_NET_CLS_ACT
48 		switch (err) {
49 		case TC_ACT_STOLEN:
50 		case TC_ACT_QUEUED:
51 		case TC_ACT_TRAP:
52 			*qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
53 			/* fall through */
54 		case TC_ACT_SHOT:
55 			return NULL;
56 		}
57 #endif
58 		if (!fl || err < 0) {
59 			if (TC_H_MAJ(band))
60 				band = 0;
61 			return q->queues[q->prio2band[band & TC_PRIO_MAX]];
62 		}
63 		band = res.classid;
64 	}
65 	band = TC_H_MIN(band) - 1;
66 	if (band >= q->bands)
67 		return q->queues[q->prio2band[0]];
68 
69 	return q->queues[band];
70 }
71 
72 static int
73 prio_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free)
74 {
75 	struct Qdisc *qdisc;
76 	int ret;
77 
78 	qdisc = prio_classify(skb, sch, &ret);
79 #ifdef CONFIG_NET_CLS_ACT
80 	if (qdisc == NULL) {
81 
82 		if (ret & __NET_XMIT_BYPASS)
83 			qdisc_qstats_drop(sch);
84 		__qdisc_drop(skb, to_free);
85 		return ret;
86 	}
87 #endif
88 
89 	ret = qdisc_enqueue(skb, qdisc, to_free);
90 	if (ret == NET_XMIT_SUCCESS) {
91 		qdisc_qstats_backlog_inc(sch, skb);
92 		sch->q.qlen++;
93 		return NET_XMIT_SUCCESS;
94 	}
95 	if (net_xmit_drop_count(ret))
96 		qdisc_qstats_drop(sch);
97 	return ret;
98 }
99 
100 static struct sk_buff *prio_peek(struct Qdisc *sch)
101 {
102 	struct prio_sched_data *q = qdisc_priv(sch);
103 	int prio;
104 
105 	for (prio = 0; prio < q->bands; prio++) {
106 		struct Qdisc *qdisc = q->queues[prio];
107 		struct sk_buff *skb = qdisc->ops->peek(qdisc);
108 		if (skb)
109 			return skb;
110 	}
111 	return NULL;
112 }
113 
114 static struct sk_buff *prio_dequeue(struct Qdisc *sch)
115 {
116 	struct prio_sched_data *q = qdisc_priv(sch);
117 	int prio;
118 
119 	for (prio = 0; prio < q->bands; prio++) {
120 		struct Qdisc *qdisc = q->queues[prio];
121 		struct sk_buff *skb = qdisc_dequeue_peeked(qdisc);
122 		if (skb) {
123 			qdisc_bstats_update(sch, skb);
124 			qdisc_qstats_backlog_dec(sch, skb);
125 			sch->q.qlen--;
126 			return skb;
127 		}
128 	}
129 	return NULL;
130 
131 }
132 
133 static void
134 prio_reset(struct Qdisc *sch)
135 {
136 	int prio;
137 	struct prio_sched_data *q = qdisc_priv(sch);
138 
139 	for (prio = 0; prio < q->bands; prio++)
140 		qdisc_reset(q->queues[prio]);
141 	sch->qstats.backlog = 0;
142 	sch->q.qlen = 0;
143 }
144 
145 static int prio_offload(struct Qdisc *sch, bool enable)
146 {
147 	struct prio_sched_data *q = qdisc_priv(sch);
148 	struct net_device *dev = qdisc_dev(sch);
149 	struct tc_prio_qopt_offload opt = {
150 		.handle = sch->handle,
151 		.parent = sch->parent,
152 	};
153 
154 	if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc)
155 		return -EOPNOTSUPP;
156 
157 	if (enable) {
158 		opt.command = TC_PRIO_REPLACE;
159 		opt.replace_params.bands = q->bands;
160 		memcpy(&opt.replace_params.priomap, q->prio2band,
161 		       TC_PRIO_MAX + 1);
162 		opt.replace_params.qstats = &sch->qstats;
163 	} else {
164 		opt.command = TC_PRIO_DESTROY;
165 	}
166 
167 	return dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_PRIO, &opt);
168 }
169 
170 static void
171 prio_destroy(struct Qdisc *sch)
172 {
173 	int prio;
174 	struct prio_sched_data *q = qdisc_priv(sch);
175 
176 	tcf_block_put(q->block);
177 	prio_offload(sch, false);
178 	for (prio = 0; prio < q->bands; prio++)
179 		qdisc_destroy(q->queues[prio]);
180 }
181 
182 static int prio_tune(struct Qdisc *sch, struct nlattr *opt,
183 		     struct netlink_ext_ack *extack)
184 {
185 	struct prio_sched_data *q = qdisc_priv(sch);
186 	struct Qdisc *queues[TCQ_PRIO_BANDS];
187 	int oldbands = q->bands, i;
188 	struct tc_prio_qopt *qopt;
189 
190 	if (nla_len(opt) < sizeof(*qopt))
191 		return -EINVAL;
192 	qopt = nla_data(opt);
193 
194 	if (qopt->bands > TCQ_PRIO_BANDS || qopt->bands < 2)
195 		return -EINVAL;
196 
197 	for (i = 0; i <= TC_PRIO_MAX; i++) {
198 		if (qopt->priomap[i] >= qopt->bands)
199 			return -EINVAL;
200 	}
201 
202 	/* Before commit, make sure we can allocate all new qdiscs */
203 	for (i = oldbands; i < qopt->bands; i++) {
204 		queues[i] = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
205 					      TC_H_MAKE(sch->handle, i + 1),
206 					      extack);
207 		if (!queues[i]) {
208 			while (i > oldbands)
209 				qdisc_destroy(queues[--i]);
210 			return -ENOMEM;
211 		}
212 	}
213 
214 	sch_tree_lock(sch);
215 	q->bands = qopt->bands;
216 	memcpy(q->prio2band, qopt->priomap, TC_PRIO_MAX+1);
217 
218 	for (i = q->bands; i < oldbands; i++) {
219 		struct Qdisc *child = q->queues[i];
220 
221 		qdisc_tree_reduce_backlog(child, child->q.qlen,
222 					  child->qstats.backlog);
223 		qdisc_destroy(child);
224 	}
225 
226 	for (i = oldbands; i < q->bands; i++) {
227 		q->queues[i] = queues[i];
228 		if (q->queues[i] != &noop_qdisc)
229 			qdisc_hash_add(q->queues[i], true);
230 	}
231 
232 	sch_tree_unlock(sch);
233 	prio_offload(sch, true);
234 	return 0;
235 }
236 
237 static int prio_init(struct Qdisc *sch, struct nlattr *opt,
238 		     struct netlink_ext_ack *extack)
239 {
240 	struct prio_sched_data *q = qdisc_priv(sch);
241 	int err;
242 
243 	if (!opt)
244 		return -EINVAL;
245 
246 	err = tcf_block_get(&q->block, &q->filter_list, sch, extack);
247 	if (err)
248 		return err;
249 
250 	return prio_tune(sch, opt, extack);
251 }
252 
253 static int prio_dump_offload(struct Qdisc *sch)
254 {
255 	struct net_device *dev = qdisc_dev(sch);
256 	struct tc_prio_qopt_offload hw_stats = {
257 		.command = TC_PRIO_STATS,
258 		.handle = sch->handle,
259 		.parent = sch->parent,
260 		{
261 			.stats = {
262 				.bstats = &sch->bstats,
263 				.qstats = &sch->qstats,
264 			},
265 		},
266 	};
267 	int err;
268 
269 	sch->flags &= ~TCQ_F_OFFLOADED;
270 	if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc)
271 		return 0;
272 
273 	err = dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_PRIO,
274 					    &hw_stats);
275 	if (err == -EOPNOTSUPP)
276 		return 0;
277 
278 	if (!err)
279 		sch->flags |= TCQ_F_OFFLOADED;
280 
281 	return err;
282 }
283 
284 static int prio_dump(struct Qdisc *sch, struct sk_buff *skb)
285 {
286 	struct prio_sched_data *q = qdisc_priv(sch);
287 	unsigned char *b = skb_tail_pointer(skb);
288 	struct tc_prio_qopt opt;
289 	int err;
290 
291 	opt.bands = q->bands;
292 	memcpy(&opt.priomap, q->prio2band, TC_PRIO_MAX + 1);
293 
294 	err = prio_dump_offload(sch);
295 	if (err)
296 		goto nla_put_failure;
297 
298 	if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
299 		goto nla_put_failure;
300 
301 	return skb->len;
302 
303 nla_put_failure:
304 	nlmsg_trim(skb, b);
305 	return -1;
306 }
307 
308 static int prio_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
309 		      struct Qdisc **old, struct netlink_ext_ack *extack)
310 {
311 	struct prio_sched_data *q = qdisc_priv(sch);
312 	unsigned long band = arg - 1;
313 
314 	if (new == NULL)
315 		new = &noop_qdisc;
316 
317 	*old = qdisc_replace(sch, new, &q->queues[band]);
318 	return 0;
319 }
320 
321 static struct Qdisc *
322 prio_leaf(struct Qdisc *sch, unsigned long arg)
323 {
324 	struct prio_sched_data *q = qdisc_priv(sch);
325 	unsigned long band = arg - 1;
326 
327 	return q->queues[band];
328 }
329 
330 static unsigned long prio_find(struct Qdisc *sch, u32 classid)
331 {
332 	struct prio_sched_data *q = qdisc_priv(sch);
333 	unsigned long band = TC_H_MIN(classid);
334 
335 	if (band - 1 >= q->bands)
336 		return 0;
337 	return band;
338 }
339 
340 static unsigned long prio_bind(struct Qdisc *sch, unsigned long parent, u32 classid)
341 {
342 	return prio_find(sch, classid);
343 }
344 
345 
346 static void prio_unbind(struct Qdisc *q, unsigned long cl)
347 {
348 }
349 
350 static int prio_dump_class(struct Qdisc *sch, unsigned long cl, struct sk_buff *skb,
351 			   struct tcmsg *tcm)
352 {
353 	struct prio_sched_data *q = qdisc_priv(sch);
354 
355 	tcm->tcm_handle |= TC_H_MIN(cl);
356 	tcm->tcm_info = q->queues[cl-1]->handle;
357 	return 0;
358 }
359 
360 static int prio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
361 				 struct gnet_dump *d)
362 {
363 	struct prio_sched_data *q = qdisc_priv(sch);
364 	struct Qdisc *cl_q;
365 
366 	cl_q = q->queues[cl - 1];
367 	if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch),
368 				  d, NULL, &cl_q->bstats) < 0 ||
369 	    gnet_stats_copy_queue(d, NULL, &cl_q->qstats, cl_q->q.qlen) < 0)
370 		return -1;
371 
372 	return 0;
373 }
374 
375 static void prio_walk(struct Qdisc *sch, struct qdisc_walker *arg)
376 {
377 	struct prio_sched_data *q = qdisc_priv(sch);
378 	int prio;
379 
380 	if (arg->stop)
381 		return;
382 
383 	for (prio = 0; prio < q->bands; prio++) {
384 		if (arg->count < arg->skip) {
385 			arg->count++;
386 			continue;
387 		}
388 		if (arg->fn(sch, prio + 1, arg) < 0) {
389 			arg->stop = 1;
390 			break;
391 		}
392 		arg->count++;
393 	}
394 }
395 
396 static struct tcf_block *prio_tcf_block(struct Qdisc *sch, unsigned long cl,
397 					struct netlink_ext_ack *extack)
398 {
399 	struct prio_sched_data *q = qdisc_priv(sch);
400 
401 	if (cl)
402 		return NULL;
403 	return q->block;
404 }
405 
406 static const struct Qdisc_class_ops prio_class_ops = {
407 	.graft		=	prio_graft,
408 	.leaf		=	prio_leaf,
409 	.find		=	prio_find,
410 	.walk		=	prio_walk,
411 	.tcf_block	=	prio_tcf_block,
412 	.bind_tcf	=	prio_bind,
413 	.unbind_tcf	=	prio_unbind,
414 	.dump		=	prio_dump_class,
415 	.dump_stats	=	prio_dump_class_stats,
416 };
417 
418 static struct Qdisc_ops prio_qdisc_ops __read_mostly = {
419 	.next		=	NULL,
420 	.cl_ops		=	&prio_class_ops,
421 	.id		=	"prio",
422 	.priv_size	=	sizeof(struct prio_sched_data),
423 	.enqueue	=	prio_enqueue,
424 	.dequeue	=	prio_dequeue,
425 	.peek		=	prio_peek,
426 	.init		=	prio_init,
427 	.reset		=	prio_reset,
428 	.destroy	=	prio_destroy,
429 	.change		=	prio_tune,
430 	.dump		=	prio_dump,
431 	.owner		=	THIS_MODULE,
432 };
433 
434 static int __init prio_module_init(void)
435 {
436 	return register_qdisc(&prio_qdisc_ops);
437 }
438 
439 static void __exit prio_module_exit(void)
440 {
441 	unregister_qdisc(&prio_qdisc_ops);
442 }
443 
444 module_init(prio_module_init)
445 module_exit(prio_module_exit)
446 
447 MODULE_LICENSE("GPL");
448