1 /* SPDX-License-Identifier: BSD-3-Clause
2 *
3 * Copyright (c) 2018-2020 Arm Limited
4 */
5
6 #include <stdio.h>
7 #include <string.h>
8 #include <stdint.h>
9 #include <inttypes.h>
10 #include <errno.h>
11
12 #include <rte_common.h>
13 #include <rte_log.h>
14 #include <rte_memory.h>
15 #include <rte_malloc.h>
16 #include <rte_eal.h>
17 #include <rte_atomic.h>
18 #include <rte_per_lcore.h>
19 #include <rte_lcore.h>
20 #include <rte_errno.h>
21 #include <rte_ring_elem.h>
22
23 #include "rte_rcu_qsbr.h"
24 #include "rcu_qsbr_pvt.h"
25
26 /* Get the memory size of QSBR variable */
27 size_t
rte_rcu_qsbr_get_memsize(uint32_t max_threads)28 rte_rcu_qsbr_get_memsize(uint32_t max_threads)
29 {
30 size_t sz;
31
32 if (max_threads == 0) {
33 rte_log(RTE_LOG_ERR, rte_rcu_log_type,
34 "%s(): Invalid max_threads %u\n",
35 __func__, max_threads);
36 rte_errno = EINVAL;
37
38 return 1;
39 }
40
41 sz = sizeof(struct rte_rcu_qsbr);
42
43 /* Add the size of quiescent state counter array */
44 sz += sizeof(struct rte_rcu_qsbr_cnt) * max_threads;
45
46 /* Add the size of the registered thread ID bitmap array */
47 sz += __RTE_QSBR_THRID_ARRAY_SIZE(max_threads);
48
49 return sz;
50 }
51
52 /* Initialize a quiescent state variable */
53 int
rte_rcu_qsbr_init(struct rte_rcu_qsbr * v,uint32_t max_threads)54 rte_rcu_qsbr_init(struct rte_rcu_qsbr *v, uint32_t max_threads)
55 {
56 size_t sz;
57
58 if (v == NULL) {
59 rte_log(RTE_LOG_ERR, rte_rcu_log_type,
60 "%s(): Invalid input parameter\n", __func__);
61 rte_errno = EINVAL;
62
63 return 1;
64 }
65
66 sz = rte_rcu_qsbr_get_memsize(max_threads);
67 if (sz == 1)
68 return 1;
69
70 /* Set all the threads to offline */
71 memset(v, 0, sz);
72 v->max_threads = max_threads;
73 v->num_elems = RTE_ALIGN_MUL_CEIL(max_threads,
74 __RTE_QSBR_THRID_ARRAY_ELM_SIZE) /
75 __RTE_QSBR_THRID_ARRAY_ELM_SIZE;
76 v->token = __RTE_QSBR_CNT_INIT;
77 v->acked_token = __RTE_QSBR_CNT_INIT - 1;
78
79 return 0;
80 }
81
82 /* Register a reader thread to report its quiescent state
83 * on a QS variable.
84 */
85 int
rte_rcu_qsbr_thread_register(struct rte_rcu_qsbr * v,unsigned int thread_id)86 rte_rcu_qsbr_thread_register(struct rte_rcu_qsbr *v, unsigned int thread_id)
87 {
88 unsigned int i, id, success;
89 uint64_t old_bmap, new_bmap;
90
91 if (v == NULL || thread_id >= v->max_threads) {
92 rte_log(RTE_LOG_ERR, rte_rcu_log_type,
93 "%s(): Invalid input parameter\n", __func__);
94 rte_errno = EINVAL;
95
96 return 1;
97 }
98
99 __RTE_RCU_IS_LOCK_CNT_ZERO(v, thread_id, ERR, "Lock counter %u\n",
100 v->qsbr_cnt[thread_id].lock_cnt);
101
102 id = thread_id & __RTE_QSBR_THRID_MASK;
103 i = thread_id >> __RTE_QSBR_THRID_INDEX_SHIFT;
104
105 /* Make sure that the counter for registered threads does not
106 * go out of sync. Hence, additional checks are required.
107 */
108 /* Check if the thread is already registered */
109 old_bmap = __atomic_load_n(__RTE_QSBR_THRID_ARRAY_ELM(v, i),
110 __ATOMIC_RELAXED);
111 if (old_bmap & 1UL << id)
112 return 0;
113
114 do {
115 new_bmap = old_bmap | (1UL << id);
116 success = __atomic_compare_exchange(
117 __RTE_QSBR_THRID_ARRAY_ELM(v, i),
118 &old_bmap, &new_bmap, 0,
119 __ATOMIC_RELEASE, __ATOMIC_RELAXED);
120
121 if (success)
122 __atomic_fetch_add(&v->num_threads,
123 1, __ATOMIC_RELAXED);
124 else if (old_bmap & (1UL << id))
125 /* Someone else registered this thread.
126 * Counter should not be incremented.
127 */
128 return 0;
129 } while (success == 0);
130
131 return 0;
132 }
133
134 /* Remove a reader thread, from the list of threads reporting their
135 * quiescent state on a QS variable.
136 */
137 int
rte_rcu_qsbr_thread_unregister(struct rte_rcu_qsbr * v,unsigned int thread_id)138 rte_rcu_qsbr_thread_unregister(struct rte_rcu_qsbr *v, unsigned int thread_id)
139 {
140 unsigned int i, id, success;
141 uint64_t old_bmap, new_bmap;
142
143 if (v == NULL || thread_id >= v->max_threads) {
144 rte_log(RTE_LOG_ERR, rte_rcu_log_type,
145 "%s(): Invalid input parameter\n", __func__);
146 rte_errno = EINVAL;
147
148 return 1;
149 }
150
151 __RTE_RCU_IS_LOCK_CNT_ZERO(v, thread_id, ERR, "Lock counter %u\n",
152 v->qsbr_cnt[thread_id].lock_cnt);
153
154 id = thread_id & __RTE_QSBR_THRID_MASK;
155 i = thread_id >> __RTE_QSBR_THRID_INDEX_SHIFT;
156
157 /* Make sure that the counter for registered threads does not
158 * go out of sync. Hence, additional checks are required.
159 */
160 /* Check if the thread is already unregistered */
161 old_bmap = __atomic_load_n(__RTE_QSBR_THRID_ARRAY_ELM(v, i),
162 __ATOMIC_RELAXED);
163 if (!(old_bmap & (1UL << id)))
164 return 0;
165
166 do {
167 new_bmap = old_bmap & ~(1UL << id);
168 /* Make sure any loads of the shared data structure are
169 * completed before removal of the thread from the list of
170 * reporting threads.
171 */
172 success = __atomic_compare_exchange(
173 __RTE_QSBR_THRID_ARRAY_ELM(v, i),
174 &old_bmap, &new_bmap, 0,
175 __ATOMIC_RELEASE, __ATOMIC_RELAXED);
176
177 if (success)
178 __atomic_fetch_sub(&v->num_threads,
179 1, __ATOMIC_RELAXED);
180 else if (!(old_bmap & (1UL << id)))
181 /* Someone else unregistered this thread.
182 * Counter should not be incremented.
183 */
184 return 0;
185 } while (success == 0);
186
187 return 0;
188 }
189
190 /* Wait till the reader threads have entered quiescent state. */
191 void
rte_rcu_qsbr_synchronize(struct rte_rcu_qsbr * v,unsigned int thread_id)192 rte_rcu_qsbr_synchronize(struct rte_rcu_qsbr *v, unsigned int thread_id)
193 {
194 uint64_t t;
195
196 RTE_ASSERT(v != NULL);
197
198 t = rte_rcu_qsbr_start(v);
199
200 /* If the current thread has readside critical section,
201 * update its quiescent state status.
202 */
203 if (thread_id != RTE_QSBR_THRID_INVALID)
204 rte_rcu_qsbr_quiescent(v, thread_id);
205
206 /* Wait for other readers to enter quiescent state */
207 rte_rcu_qsbr_check(v, t, true);
208 }
209
210 /* Dump the details of a single quiescent state variable to a file. */
211 int
rte_rcu_qsbr_dump(FILE * f,struct rte_rcu_qsbr * v)212 rte_rcu_qsbr_dump(FILE *f, struct rte_rcu_qsbr *v)
213 {
214 uint64_t bmap;
215 uint32_t i, t, id;
216
217 if (v == NULL || f == NULL) {
218 rte_log(RTE_LOG_ERR, rte_rcu_log_type,
219 "%s(): Invalid input parameter\n", __func__);
220 rte_errno = EINVAL;
221
222 return 1;
223 }
224
225 fprintf(f, "\nQuiescent State Variable @%p\n", v);
226
227 fprintf(f, " QS variable memory size = %zu\n",
228 rte_rcu_qsbr_get_memsize(v->max_threads));
229 fprintf(f, " Given # max threads = %u\n", v->max_threads);
230 fprintf(f, " Current # threads = %u\n", v->num_threads);
231
232 fprintf(f, " Registered thread IDs = ");
233 for (i = 0; i < v->num_elems; i++) {
234 bmap = __atomic_load_n(__RTE_QSBR_THRID_ARRAY_ELM(v, i),
235 __ATOMIC_ACQUIRE);
236 id = i << __RTE_QSBR_THRID_INDEX_SHIFT;
237 while (bmap) {
238 t = __builtin_ctzl(bmap);
239 fprintf(f, "%u ", id + t);
240
241 bmap &= ~(1UL << t);
242 }
243 }
244
245 fprintf(f, "\n");
246
247 fprintf(f, " Token = %" PRIu64 "\n",
248 __atomic_load_n(&v->token, __ATOMIC_ACQUIRE));
249
250 fprintf(f, " Least Acknowledged Token = %" PRIu64 "\n",
251 __atomic_load_n(&v->acked_token, __ATOMIC_ACQUIRE));
252
253 fprintf(f, "Quiescent State Counts for readers:\n");
254 for (i = 0; i < v->num_elems; i++) {
255 bmap = __atomic_load_n(__RTE_QSBR_THRID_ARRAY_ELM(v, i),
256 __ATOMIC_ACQUIRE);
257 id = i << __RTE_QSBR_THRID_INDEX_SHIFT;
258 while (bmap) {
259 t = __builtin_ctzl(bmap);
260 fprintf(f, "thread ID = %u, count = %" PRIu64 ", lock count = %u\n",
261 id + t,
262 __atomic_load_n(
263 &v->qsbr_cnt[id + t].cnt,
264 __ATOMIC_RELAXED),
265 __atomic_load_n(
266 &v->qsbr_cnt[id + t].lock_cnt,
267 __ATOMIC_RELAXED));
268 bmap &= ~(1UL << t);
269 }
270 }
271
272 return 0;
273 }
274
275 /* Create a queue used to store the data structure elements that can
276 * be freed later. This queue is referred to as 'defer queue'.
277 */
278 struct rte_rcu_qsbr_dq *
rte_rcu_qsbr_dq_create(const struct rte_rcu_qsbr_dq_parameters * params)279 rte_rcu_qsbr_dq_create(const struct rte_rcu_qsbr_dq_parameters *params)
280 {
281 struct rte_rcu_qsbr_dq *dq;
282 uint32_t qs_fifo_size;
283 unsigned int flags;
284
285 if (params == NULL || params->free_fn == NULL ||
286 params->v == NULL || params->name == NULL ||
287 params->size == 0 || params->esize == 0 ||
288 (params->esize % 4 != 0)) {
289 rte_log(RTE_LOG_ERR, rte_rcu_log_type,
290 "%s(): Invalid input parameter\n", __func__);
291 rte_errno = EINVAL;
292
293 return NULL;
294 }
295 /* If auto reclamation is configured, reclaim limit
296 * should be a valid value.
297 */
298 if ((params->trigger_reclaim_limit <= params->size) &&
299 (params->max_reclaim_size == 0)) {
300 rte_log(RTE_LOG_ERR, rte_rcu_log_type,
301 "%s(): Invalid input parameter, size = %u, trigger_reclaim_limit = %u, max_reclaim_size = %u\n",
302 __func__, params->size, params->trigger_reclaim_limit,
303 params->max_reclaim_size);
304 rte_errno = EINVAL;
305
306 return NULL;
307 }
308
309 dq = rte_zmalloc(NULL, sizeof(struct rte_rcu_qsbr_dq),
310 RTE_CACHE_LINE_SIZE);
311 if (dq == NULL) {
312 rte_errno = ENOMEM;
313
314 return NULL;
315 }
316
317 /* Decide the flags for the ring.
318 * If MT safety is requested, use RTS for ring enqueue as most
319 * use cases involve dq-enqueue happening on the control plane.
320 * Ring dequeue is always HTS due to the possibility of revert.
321 */
322 flags = RING_F_MP_RTS_ENQ;
323 if (params->flags & RTE_RCU_QSBR_DQ_MT_UNSAFE)
324 flags = RING_F_SP_ENQ;
325 flags |= RING_F_MC_HTS_DEQ;
326 /* round up qs_fifo_size to next power of two that is not less than
327 * max_size.
328 */
329 qs_fifo_size = rte_align32pow2(params->size + 1);
330 /* Add token size to ring element size */
331 dq->r = rte_ring_create_elem(params->name,
332 __RTE_QSBR_TOKEN_SIZE + params->esize,
333 qs_fifo_size, SOCKET_ID_ANY, flags);
334 if (dq->r == NULL) {
335 rte_log(RTE_LOG_ERR, rte_rcu_log_type,
336 "%s(): defer queue create failed\n", __func__);
337 rte_free(dq);
338 return NULL;
339 }
340
341 dq->v = params->v;
342 dq->size = params->size;
343 dq->esize = __RTE_QSBR_TOKEN_SIZE + params->esize;
344 dq->trigger_reclaim_limit = params->trigger_reclaim_limit;
345 dq->max_reclaim_size = params->max_reclaim_size;
346 dq->free_fn = params->free_fn;
347 dq->p = params->p;
348
349 return dq;
350 }
351
352 /* Enqueue one resource to the defer queue to free after the grace
353 * period is over.
354 */
rte_rcu_qsbr_dq_enqueue(struct rte_rcu_qsbr_dq * dq,void * e)355 int rte_rcu_qsbr_dq_enqueue(struct rte_rcu_qsbr_dq *dq, void *e)
356 {
357 __rte_rcu_qsbr_dq_elem_t *dq_elem;
358 uint32_t cur_size;
359
360 if (dq == NULL || e == NULL) {
361 rte_log(RTE_LOG_ERR, rte_rcu_log_type,
362 "%s(): Invalid input parameter\n", __func__);
363 rte_errno = EINVAL;
364
365 return 1;
366 }
367
368 char data[dq->esize];
369 dq_elem = (__rte_rcu_qsbr_dq_elem_t *)data;
370 /* Start the grace period */
371 dq_elem->token = rte_rcu_qsbr_start(dq->v);
372
373 /* Reclaim resources if the queue size has hit the reclaim
374 * limit. This helps the queue from growing too large and
375 * allows time for reader threads to report their quiescent state.
376 */
377 cur_size = rte_ring_count(dq->r);
378 if (cur_size > dq->trigger_reclaim_limit) {
379 rte_log(RTE_LOG_INFO, rte_rcu_log_type,
380 "%s(): Triggering reclamation\n", __func__);
381 rte_rcu_qsbr_dq_reclaim(dq, dq->max_reclaim_size,
382 NULL, NULL, NULL);
383 }
384
385 /* Enqueue the token and resource. Generating the token and
386 * enqueuing (token + resource) on the queue is not an
387 * atomic operation. When the defer queue is shared by multiple
388 * writers, this might result in tokens enqueued out of order
389 * on the queue. So, some tokens might wait longer than they
390 * are required to be reclaimed.
391 */
392 memcpy(dq_elem->elem, e, dq->esize - __RTE_QSBR_TOKEN_SIZE);
393 /* Check the status as enqueue might fail since the other threads
394 * might have used up the freed space.
395 * Enqueue uses the configured flags when the DQ was created.
396 */
397 if (rte_ring_enqueue_elem(dq->r, data, dq->esize) != 0) {
398 rte_log(RTE_LOG_ERR, rte_rcu_log_type,
399 "%s(): Enqueue failed\n", __func__);
400 /* Note that the token generated above is not used.
401 * Other than wasting tokens, it should not cause any
402 * other issues.
403 */
404 rte_log(RTE_LOG_INFO, rte_rcu_log_type,
405 "%s(): Skipped enqueuing token = %" PRIu64 "\n",
406 __func__, dq_elem->token);
407
408 rte_errno = ENOSPC;
409 return 1;
410 }
411
412 rte_log(RTE_LOG_INFO, rte_rcu_log_type,
413 "%s(): Enqueued token = %" PRIu64 "\n",
414 __func__, dq_elem->token);
415
416 return 0;
417 }
418
419 /* Reclaim resources from the defer queue. */
420 int
rte_rcu_qsbr_dq_reclaim(struct rte_rcu_qsbr_dq * dq,unsigned int n,unsigned int * freed,unsigned int * pending,unsigned int * available)421 rte_rcu_qsbr_dq_reclaim(struct rte_rcu_qsbr_dq *dq, unsigned int n,
422 unsigned int *freed, unsigned int *pending,
423 unsigned int *available)
424 {
425 uint32_t cnt;
426 __rte_rcu_qsbr_dq_elem_t *dq_elem;
427
428 if (dq == NULL || n == 0) {
429 rte_log(RTE_LOG_ERR, rte_rcu_log_type,
430 "%s(): Invalid input parameter\n", __func__);
431 rte_errno = EINVAL;
432
433 return 1;
434 }
435
436 cnt = 0;
437
438 char data[dq->esize];
439 /* Check reader threads quiescent state and reclaim resources */
440 while (cnt < n &&
441 rte_ring_dequeue_bulk_elem_start(dq->r, &data,
442 dq->esize, 1, available) != 0) {
443 dq_elem = (__rte_rcu_qsbr_dq_elem_t *)data;
444
445 /* Reclaim the resource */
446 if (rte_rcu_qsbr_check(dq->v, dq_elem->token, false) != 1) {
447 rte_ring_dequeue_elem_finish(dq->r, 0);
448 break;
449 }
450 rte_ring_dequeue_elem_finish(dq->r, 1);
451
452 rte_log(RTE_LOG_INFO, rte_rcu_log_type,
453 "%s(): Reclaimed token = %" PRIu64 "\n",
454 __func__, dq_elem->token);
455
456 dq->free_fn(dq->p, dq_elem->elem, 1);
457
458 cnt++;
459 }
460
461 rte_log(RTE_LOG_INFO, rte_rcu_log_type,
462 "%s(): Reclaimed %u resources\n", __func__, cnt);
463
464 if (freed != NULL)
465 *freed = cnt;
466 if (pending != NULL)
467 *pending = rte_ring_count(dq->r);
468
469 return 0;
470 }
471
472 /* Delete a defer queue. */
473 int
rte_rcu_qsbr_dq_delete(struct rte_rcu_qsbr_dq * dq)474 rte_rcu_qsbr_dq_delete(struct rte_rcu_qsbr_dq *dq)
475 {
476 unsigned int pending;
477
478 if (dq == NULL) {
479 rte_log(RTE_LOG_DEBUG, rte_rcu_log_type,
480 "%s(): Invalid input parameter\n", __func__);
481
482 return 0;
483 }
484
485 /* Reclaim all the resources */
486 rte_rcu_qsbr_dq_reclaim(dq, ~0, NULL, &pending, NULL);
487 if (pending != 0) {
488 rte_errno = EAGAIN;
489
490 return 1;
491 }
492
493 rte_ring_free(dq->r);
494 rte_free(dq);
495
496 return 0;
497 }
498
499 RTE_LOG_REGISTER(rte_rcu_log_type, lib.rcu, ERR);
500