Commit | Line | Data |
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852c2936 MD |
1 | /* |
2 | * ring_buffer_frontend.c | |
3 | * | |
4 | * (C) Copyright 2005-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
5 | * | |
6 | * Ring buffer wait-free buffer synchronization. Producer-consumer and flight | |
7 | * recorder (overwrite) modes. See thesis: | |
8 | * | |
9 | * Desnoyers, Mathieu (2009), "Low-Impact Operating System Tracing", Ph.D. | |
10 | * dissertation, Ecole Polytechnique de Montreal. | |
11 | * http://www.lttng.org/pub/thesis/desnoyers-dissertation-2009-12.pdf | |
12 | * | |
13 | * - Algorithm presentation in Chapter 5: | |
14 | * "Lockless Multi-Core High-Throughput Buffering". | |
15 | * - Algorithm formal verification in Section 8.6: | |
16 | * "Formal verification of LTTng" | |
17 | * | |
18 | * Author: | |
19 | * Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
20 | * | |
21 | * Inspired from LTT and RelayFS: | |
22 | * Karim Yaghmour <karim@opersys.com> | |
23 | * Tom Zanussi <zanussi@us.ibm.com> | |
24 | * Bob Wisniewski <bob@watson.ibm.com> | |
25 | * And from K42 : | |
26 | * Bob Wisniewski <bob@watson.ibm.com> | |
27 | * | |
28 | * Buffer reader semantic : | |
29 | * | |
30 | * - get_subbuf_size | |
31 | * while buffer is not finalized and empty | |
32 | * - get_subbuf | |
33 | * - if return value != 0, continue | |
34 | * - splice one subbuffer worth of data to a pipe | |
35 | * - splice the data from pipe to disk/network | |
36 | * - put_subbuf | |
37 | * | |
38 | * Dual LGPL v2.1/GPL v2 license. | |
39 | */ | |
40 | ||
a6352fd4 | 41 | #include <sys/types.h> |
431d5cf0 MD |
42 | #include <sys/mman.h> |
43 | #include <sys/stat.h> | |
44 | #include <fcntl.h> | |
14641deb | 45 | #include <urcu/compiler.h> |
a6352fd4 | 46 | #include <urcu/ref.h> |
14641deb | 47 | |
a6352fd4 | 48 | #include "smp.h" |
4931a13e MD |
49 | #include "config.h" |
50 | #include "backend.h" | |
51 | #include "frontend.h" | |
a6352fd4 | 52 | #include "shm.h" |
852c2936 | 53 | |
431d5cf0 MD |
54 | #ifndef max |
55 | #define max(a, b) ((a) > (b) ? (a) : (b)) | |
56 | #endif | |
57 | ||
852c2936 MD |
58 | /* |
59 | * Internal structure representing offsets to use at a sub-buffer switch. | |
60 | */ | |
61 | struct switch_offsets { | |
62 | unsigned long begin, end, old; | |
63 | size_t pre_header_padding, size; | |
64 | unsigned int switch_new_start:1, switch_new_end:1, switch_old_start:1, | |
65 | switch_old_end:1; | |
66 | }; | |
67 | ||
a6352fd4 | 68 | __thread unsigned int lib_ring_buffer_nesting; |
852c2936 MD |
69 | |
70 | static | |
71 | void lib_ring_buffer_print_errors(struct channel *chan, | |
72 | struct lib_ring_buffer *buf, int cpu); | |
73 | ||
74 | /* | |
75 | * Must be called under cpu hotplug protection. | |
76 | */ | |
77 | void lib_ring_buffer_free(struct lib_ring_buffer *buf) | |
78 | { | |
a6352fd4 | 79 | struct channel *chan = shmp(buf->backend.chan); |
852c2936 MD |
80 | |
81 | lib_ring_buffer_print_errors(chan, buf, buf->backend.cpu); | |
431d5cf0 MD |
82 | /* buf->commit_hot will be freed by shm teardown */ |
83 | /* buf->commit_cold will be freed by shm teardown */ | |
852c2936 MD |
84 | |
85 | lib_ring_buffer_backend_free(&buf->backend); | |
86 | } | |
87 | ||
88 | /** | |
89 | * lib_ring_buffer_reset - Reset ring buffer to initial values. | |
90 | * @buf: Ring buffer. | |
91 | * | |
92 | * Effectively empty the ring buffer. Should be called when the buffer is not | |
93 | * used for writing. The ring buffer can be opened for reading, but the reader | |
94 | * should not be using the iterator concurrently with reset. The previous | |
95 | * current iterator record is reset. | |
96 | */ | |
97 | void lib_ring_buffer_reset(struct lib_ring_buffer *buf) | |
98 | { | |
a6352fd4 | 99 | struct channel *chan = shmp(buf->backend.chan); |
852c2936 MD |
100 | const struct lib_ring_buffer_config *config = chan->backend.config; |
101 | unsigned int i; | |
102 | ||
103 | /* | |
104 | * Reset iterator first. It will put the subbuffer if it currently holds | |
105 | * it. | |
106 | */ | |
852c2936 MD |
107 | v_set(config, &buf->offset, 0); |
108 | for (i = 0; i < chan->backend.num_subbuf; i++) { | |
a6352fd4 MD |
109 | v_set(config, &shmp(buf->commit_hot)[i].cc, 0); |
110 | v_set(config, &shmp(buf->commit_hot)[i].seq, 0); | |
111 | v_set(config, &shmp(buf->commit_cold)[i].cc_sb, 0); | |
852c2936 | 112 | } |
a6352fd4 MD |
113 | uatomic_set(&buf->consumed, 0); |
114 | uatomic_set(&buf->record_disabled, 0); | |
852c2936 MD |
115 | v_set(config, &buf->last_tsc, 0); |
116 | lib_ring_buffer_backend_reset(&buf->backend); | |
117 | /* Don't reset number of active readers */ | |
118 | v_set(config, &buf->records_lost_full, 0); | |
119 | v_set(config, &buf->records_lost_wrap, 0); | |
120 | v_set(config, &buf->records_lost_big, 0); | |
121 | v_set(config, &buf->records_count, 0); | |
122 | v_set(config, &buf->records_overrun, 0); | |
123 | buf->finalized = 0; | |
124 | } | |
852c2936 MD |
125 | |
126 | /** | |
127 | * channel_reset - Reset channel to initial values. | |
128 | * @chan: Channel. | |
129 | * | |
130 | * Effectively empty the channel. Should be called when the channel is not used | |
131 | * for writing. The channel can be opened for reading, but the reader should not | |
132 | * be using the iterator concurrently with reset. The previous current iterator | |
133 | * record is reset. | |
134 | */ | |
135 | void channel_reset(struct channel *chan) | |
136 | { | |
137 | /* | |
138 | * Reset iterators first. Will put the subbuffer if held for reading. | |
139 | */ | |
a6352fd4 | 140 | uatomic_set(&chan->record_disabled, 0); |
852c2936 MD |
141 | /* Don't reset commit_count_mask, still valid */ |
142 | channel_backend_reset(&chan->backend); | |
143 | /* Don't reset switch/read timer interval */ | |
144 | /* Don't reset notifiers and notifier enable bits */ | |
145 | /* Don't reset reader reference count */ | |
146 | } | |
852c2936 MD |
147 | |
148 | /* | |
149 | * Must be called under cpu hotplug protection. | |
150 | */ | |
151 | int lib_ring_buffer_create(struct lib_ring_buffer *buf, | |
a6352fd4 MD |
152 | struct channel_backend *chanb, int cpu, |
153 | struct shm_header *shm_header) | |
852c2936 MD |
154 | { |
155 | const struct lib_ring_buffer_config *config = chanb->config; | |
14641deb | 156 | struct channel *chan = caa_container_of(chanb, struct channel, backend); |
852c2936 MD |
157 | void *priv = chanb->priv; |
158 | unsigned int num_subbuf; | |
159 | size_t subbuf_header_size; | |
160 | u64 tsc; | |
161 | int ret; | |
162 | ||
163 | /* Test for cpu hotplug */ | |
164 | if (buf->backend.allocated) | |
165 | return 0; | |
166 | ||
a6352fd4 MD |
167 | ret = lib_ring_buffer_backend_create(&buf->backend, &chan->backend, |
168 | cpu, shm_header); | |
852c2936 MD |
169 | if (ret) |
170 | return ret; | |
171 | ||
431d5cf0 MD |
172 | align_shm(shm_header, |
173 | max(__alignof__(struct commit_counters_hot), | |
174 | __alignof__(struct commit_counters_cold))); | |
a6352fd4 MD |
175 | set_shmp(&buf->commit_hot, |
176 | zalloc_shm(shm_header, | |
177 | sizeof(*buf->commit_hot) * chan->backend.num_subbuf)); | |
178 | if (!shmp(buf->commit_hot)) { | |
852c2936 MD |
179 | ret = -ENOMEM; |
180 | goto free_chanbuf; | |
181 | } | |
182 | ||
431d5cf0 | 183 | align_shm(shm_header, __alignof__(struct commit_counters_cold)); |
a6352fd4 MD |
184 | set_shmp(&buf->commit_cold, |
185 | zalloc_shm(shm_header, | |
186 | sizeof(*buf->commit_cold) * chan->backend.num_subbuf)); | |
187 | if (!shmp(buf->commit_cold)) { | |
852c2936 MD |
188 | ret = -ENOMEM; |
189 | goto free_commit; | |
190 | } | |
191 | ||
192 | num_subbuf = chan->backend.num_subbuf; | |
a6352fd4 | 193 | //init_waitqueue_head(&buf->read_wait); |
852c2936 MD |
194 | |
195 | /* | |
196 | * Write the subbuffer header for first subbuffer so we know the total | |
197 | * duration of data gathering. | |
198 | */ | |
199 | subbuf_header_size = config->cb.subbuffer_header_size(); | |
200 | v_set(config, &buf->offset, subbuf_header_size); | |
a6352fd4 MD |
201 | subbuffer_id_clear_noref(config, &shmp(buf->backend.buf_wsb)[0].id); |
202 | tsc = config->cb.ring_buffer_clock_read(shmp(buf->backend.chan)); | |
852c2936 | 203 | config->cb.buffer_begin(buf, tsc, 0); |
a6352fd4 | 204 | v_add(config, subbuf_header_size, &shmp(buf->commit_hot)[0].cc); |
852c2936 MD |
205 | |
206 | if (config->cb.buffer_create) { | |
207 | ret = config->cb.buffer_create(buf, priv, cpu, chanb->name); | |
208 | if (ret) | |
209 | goto free_init; | |
210 | } | |
852c2936 | 211 | buf->backend.allocated = 1; |
852c2936 MD |
212 | return 0; |
213 | ||
214 | /* Error handling */ | |
215 | free_init: | |
a6352fd4 | 216 | /* commit_cold will be freed by shm teardown */ |
852c2936 | 217 | free_commit: |
a6352fd4 | 218 | /* commit_hot will be freed by shm teardown */ |
852c2936 MD |
219 | free_chanbuf: |
220 | lib_ring_buffer_backend_free(&buf->backend); | |
221 | return ret; | |
222 | } | |
223 | ||
224 | static void switch_buffer_timer(unsigned long data) | |
225 | { | |
226 | struct lib_ring_buffer *buf = (struct lib_ring_buffer *)data; | |
a6352fd4 | 227 | struct channel *chan = shmp(buf->backend.chan); |
852c2936 MD |
228 | const struct lib_ring_buffer_config *config = chan->backend.config; |
229 | ||
230 | /* | |
231 | * Only flush buffers periodically if readers are active. | |
232 | */ | |
a6352fd4 | 233 | if (uatomic_read(&buf->active_readers)) |
852c2936 MD |
234 | lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE); |
235 | ||
a6352fd4 MD |
236 | //TODO timers |
237 | //if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) | |
238 | // mod_timer_pinned(&buf->switch_timer, | |
239 | // jiffies + chan->switch_timer_interval); | |
240 | //else | |
241 | // mod_timer(&buf->switch_timer, | |
242 | // jiffies + chan->switch_timer_interval); | |
852c2936 MD |
243 | } |
244 | ||
852c2936 MD |
245 | static void lib_ring_buffer_start_switch_timer(struct lib_ring_buffer *buf) |
246 | { | |
a6352fd4 | 247 | struct channel *chan = shmp(buf->backend.chan); |
852c2936 MD |
248 | const struct lib_ring_buffer_config *config = chan->backend.config; |
249 | ||
250 | if (!chan->switch_timer_interval || buf->switch_timer_enabled) | |
251 | return; | |
a6352fd4 MD |
252 | //TODO |
253 | //init_timer(&buf->switch_timer); | |
254 | //buf->switch_timer.function = switch_buffer_timer; | |
255 | //buf->switch_timer.expires = jiffies + chan->switch_timer_interval; | |
256 | //buf->switch_timer.data = (unsigned long)buf; | |
257 | //if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) | |
258 | // add_timer_on(&buf->switch_timer, buf->backend.cpu); | |
259 | //else | |
260 | // add_timer(&buf->switch_timer); | |
852c2936 MD |
261 | buf->switch_timer_enabled = 1; |
262 | } | |
263 | ||
852c2936 MD |
264 | static void lib_ring_buffer_stop_switch_timer(struct lib_ring_buffer *buf) |
265 | { | |
a6352fd4 | 266 | struct channel *chan = shmp(buf->backend.chan); |
852c2936 MD |
267 | |
268 | if (!chan->switch_timer_interval || !buf->switch_timer_enabled) | |
269 | return; | |
270 | ||
a6352fd4 MD |
271 | //TODO |
272 | //del_timer_sync(&buf->switch_timer); | |
852c2936 MD |
273 | buf->switch_timer_enabled = 0; |
274 | } | |
275 | ||
276 | /* | |
277 | * Polling timer to check the channels for data. | |
278 | */ | |
279 | static void read_buffer_timer(unsigned long data) | |
280 | { | |
281 | struct lib_ring_buffer *buf = (struct lib_ring_buffer *)data; | |
a6352fd4 | 282 | struct channel *chan = shmp(buf->backend.chan); |
852c2936 MD |
283 | const struct lib_ring_buffer_config *config = chan->backend.config; |
284 | ||
285 | CHAN_WARN_ON(chan, !buf->backend.allocated); | |
286 | ||
a6352fd4 | 287 | if (uatomic_read(&buf->active_readers) |
852c2936 | 288 | && lib_ring_buffer_poll_deliver(config, buf, chan)) { |
a6352fd4 MD |
289 | //TODO |
290 | //wake_up_interruptible(&buf->read_wait); | |
291 | //wake_up_interruptible(&chan->read_wait); | |
852c2936 MD |
292 | } |
293 | ||
a6352fd4 MD |
294 | //TODO |
295 | //if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) | |
296 | // mod_timer_pinned(&buf->read_timer, | |
297 | // jiffies + chan->read_timer_interval); | |
298 | //else | |
299 | // mod_timer(&buf->read_timer, | |
300 | // jiffies + chan->read_timer_interval); | |
852c2936 MD |
301 | } |
302 | ||
852c2936 MD |
303 | static void lib_ring_buffer_start_read_timer(struct lib_ring_buffer *buf) |
304 | { | |
a6352fd4 | 305 | struct channel *chan = shmp(buf->backend.chan); |
852c2936 MD |
306 | const struct lib_ring_buffer_config *config = chan->backend.config; |
307 | ||
308 | if (config->wakeup != RING_BUFFER_WAKEUP_BY_TIMER | |
309 | || !chan->read_timer_interval | |
310 | || buf->read_timer_enabled) | |
311 | return; | |
312 | ||
a6352fd4 MD |
313 | //TODO |
314 | //init_timer(&buf->read_timer); | |
315 | //buf->read_timer.function = read_buffer_timer; | |
316 | //buf->read_timer.expires = jiffies + chan->read_timer_interval; | |
317 | //buf->read_timer.data = (unsigned long)buf; | |
852c2936 | 318 | |
a6352fd4 MD |
319 | //if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) |
320 | // add_timer_on(&buf->read_timer, buf->backend.cpu); | |
321 | //else | |
322 | // add_timer(&buf->read_timer); | |
852c2936 MD |
323 | buf->read_timer_enabled = 1; |
324 | } | |
325 | ||
852c2936 MD |
326 | static void lib_ring_buffer_stop_read_timer(struct lib_ring_buffer *buf) |
327 | { | |
a6352fd4 | 328 | struct channel *chan = shmp(buf->backend.chan); |
852c2936 MD |
329 | const struct lib_ring_buffer_config *config = chan->backend.config; |
330 | ||
331 | if (config->wakeup != RING_BUFFER_WAKEUP_BY_TIMER | |
332 | || !chan->read_timer_interval | |
333 | || !buf->read_timer_enabled) | |
334 | return; | |
335 | ||
a6352fd4 MD |
336 | //TODO |
337 | //del_timer_sync(&buf->read_timer); | |
852c2936 MD |
338 | /* |
339 | * do one more check to catch data that has been written in the last | |
340 | * timer period. | |
341 | */ | |
342 | if (lib_ring_buffer_poll_deliver(config, buf, chan)) { | |
a6352fd4 MD |
343 | //TODO |
344 | //wake_up_interruptible(&buf->read_wait); | |
345 | //wake_up_interruptible(&chan->read_wait); | |
852c2936 MD |
346 | } |
347 | buf->read_timer_enabled = 0; | |
348 | } | |
349 | ||
852c2936 MD |
350 | static void channel_unregister_notifiers(struct channel *chan) |
351 | { | |
352 | const struct lib_ring_buffer_config *config = chan->backend.config; | |
353 | int cpu; | |
354 | ||
852c2936 | 355 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) { |
852c2936 | 356 | for_each_possible_cpu(cpu) { |
a6352fd4 MD |
357 | struct lib_ring_buffer *buf = &shmp(chan->backend.buf)[cpu]; |
358 | ||
852c2936 MD |
359 | lib_ring_buffer_stop_switch_timer(buf); |
360 | lib_ring_buffer_stop_read_timer(buf); | |
361 | } | |
852c2936 | 362 | } else { |
a6352fd4 | 363 | struct lib_ring_buffer *buf = shmp(chan->backend.buf); |
852c2936 MD |
364 | |
365 | lib_ring_buffer_stop_switch_timer(buf); | |
366 | lib_ring_buffer_stop_read_timer(buf); | |
367 | } | |
368 | channel_backend_unregister_notifiers(&chan->backend); | |
369 | } | |
370 | ||
431d5cf0 | 371 | static void channel_free(struct shm_handle *handle) |
852c2936 | 372 | { |
431d5cf0 MD |
373 | struct shm_header *header = handle->header; |
374 | struct channel *chan = shmp(header->chan); | |
375 | int ret; | |
376 | ||
852c2936 | 377 | channel_backend_free(&chan->backend); |
431d5cf0 MD |
378 | /* chan is freed by shm teardown */ |
379 | ret = munmap(header, header->shm_size); | |
380 | if (ret) { | |
381 | PERROR("umnmap"); | |
382 | assert(0); | |
383 | } | |
384 | ret = close(handle->shmfd); | |
385 | if (ret) { | |
386 | PERROR("close"); | |
387 | assert(0); | |
388 | } | |
852c2936 MD |
389 | } |
390 | ||
391 | /** | |
392 | * channel_create - Create channel. | |
393 | * @config: ring buffer instance configuration | |
394 | * @name: name of the channel | |
395 | * @priv: ring buffer client private data | |
396 | * @buf_addr: pointer the the beginning of the preallocated buffer contiguous | |
397 | * address mapping. It is used only by RING_BUFFER_STATIC | |
398 | * configuration. It can be set to NULL for other backends. | |
399 | * @subbuf_size: subbuffer size | |
400 | * @num_subbuf: number of subbuffers | |
401 | * @switch_timer_interval: Time interval (in us) to fill sub-buffers with | |
402 | * padding to let readers get those sub-buffers. | |
403 | * Used for live streaming. | |
404 | * @read_timer_interval: Time interval (in us) to wake up pending readers. | |
431d5cf0 MD |
405 | * @shmfd: shared memory file descriptor (output, needs to be closed by |
406 | * the caller) | |
852c2936 MD |
407 | * |
408 | * Holds cpu hotplug. | |
409 | * Returns NULL on failure. | |
410 | */ | |
431d5cf0 | 411 | struct shm_handle *channel_create(const struct lib_ring_buffer_config *config, |
852c2936 MD |
412 | const char *name, void *priv, void *buf_addr, |
413 | size_t subbuf_size, | |
414 | size_t num_subbuf, unsigned int switch_timer_interval, | |
431d5cf0 | 415 | unsigned int read_timer_interval) |
852c2936 | 416 | { |
431d5cf0 | 417 | int ret, cpu, shmfd; |
852c2936 | 418 | struct channel *chan; |
431d5cf0 | 419 | size_t shmsize, bufshmsize, bufshmalign; |
a6352fd4 MD |
420 | struct shm_header *shm_header; |
421 | unsigned long num_subbuf_alloc; | |
431d5cf0 | 422 | struct shm_handle *handle; |
852c2936 MD |
423 | |
424 | if (lib_ring_buffer_check_config(config, switch_timer_interval, | |
425 | read_timer_interval)) | |
426 | return NULL; | |
427 | ||
431d5cf0 MD |
428 | handle = zmalloc(sizeof(struct shm_handle)); |
429 | if (!handle) | |
430 | return NULL; | |
431 | ||
a6352fd4 MD |
432 | /* Calculate the shm allocation layout */ |
433 | shmsize = sizeof(struct shm_header); | |
431d5cf0 | 434 | shmsize += offset_align(shmsize, __alignof__(struct channel)); |
a6352fd4 MD |
435 | shmsize += sizeof(struct channel); |
436 | ||
437 | /* Per-cpu buffer size: control (prior to backend) */ | |
431d5cf0 | 438 | shmsize += offset_align(shmsize, __alignof__(struct lib_ring_buffer)); |
a6352fd4 MD |
439 | bufshmsize = sizeof(struct lib_ring_buffer); |
440 | shmsize += bufshmsize * num_possible_cpus(); | |
441 | ||
442 | /* Per-cpu buffer size: backend */ | |
431d5cf0 | 443 | shmsize += offset_align(shmsize, PAGE_SIZE); |
a6352fd4 MD |
444 | /* num_subbuf + 1 is the worse case */ |
445 | num_subbuf_alloc = num_subbuf + 1; | |
446 | bufshmsize = sizeof(struct lib_ring_buffer_backend_pages *) * num_subbuf_alloc; | |
431d5cf0 MD |
447 | bufshmsize += offset_align(bufshmsize, PAGE_SIZE); |
448 | bufshmsize += subbuf_size * num_subbuf_alloc; | |
449 | bufshmsize += offset_align(bufshmsize, __alignof__(struct lib_ring_buffer_backend_pages)); | |
450 | bufshmsize += sizeof(struct lib_ring_buffer_backend_pages) * num_subbuf_alloc; | |
451 | bufshmsize += offset_align(bufshmsize, __alignof__(struct lib_ring_buffer_backend_subbuffer)); | |
a6352fd4 | 452 | bufshmsize += sizeof(struct lib_ring_buffer_backend_subbuffer) * num_subbuf; |
431d5cf0 | 453 | bufshmsize += offset_align(bufshmsize, PAGE_SIZE); |
a6352fd4 MD |
454 | shmsize += bufshmsize * num_possible_cpus(); |
455 | ||
456 | /* Per-cpu buffer size: control (after backend) */ | |
431d5cf0 MD |
457 | shmsize += offset_align(shmsize, |
458 | max(__alignof__(struct commit_counters_hot), | |
459 | __alignof__(struct commit_counters_cold))); | |
460 | bufshmsize = sizeof(struct commit_counters_hot) * num_subbuf; | |
461 | bufshmsize += offset_align(bufshmsize, __alignof__(struct commit_counters_cold)); | |
a6352fd4 | 462 | bufshmsize += sizeof(struct commit_counters_cold) * num_subbuf; |
431d5cf0 | 463 | shmsize += bufshmsize * num_possible_cpus(); |
a6352fd4 | 464 | |
431d5cf0 MD |
465 | /* |
466 | * Allocate shm, and immediately unlink its shm oject, keeping | |
467 | * only the file descriptor as a reference to the object. If it | |
468 | * already exists (caused by short race window during which the | |
469 | * global object exists in a concurrent shm_open), simply retry. | |
470 | */ | |
471 | do { | |
472 | shmfd = shm_open("/ust-shm-tmp", | |
473 | O_CREAT | O_EXCL | O_RDWR, 0700); | |
474 | } while (shmfd < 0 && errno == EEXIST); | |
475 | if (shmfd < 0) { | |
476 | PERROR("shm_open"); | |
477 | goto error_shm_open; | |
a6352fd4 | 478 | } |
431d5cf0 MD |
479 | ret = shm_unlink("/ust-shm-tmp"); |
480 | if (ret) { | |
481 | PERROR("shm_unlink"); | |
482 | goto error_unlink; | |
483 | } | |
484 | ret = ftruncate(shmfd, shmsize); | |
485 | if (ret) { | |
486 | PERROR("ftruncate"); | |
487 | goto error_ftruncate; | |
a6352fd4 | 488 | } |
852c2936 | 489 | |
431d5cf0 MD |
490 | shm_header = mmap(NULL, shmsize, PROT_READ | PROT_WRITE, |
491 | MAP_SHARED, shmfd, 0); | |
492 | if (shm_header == MAP_FAILED) { | |
493 | PERROR("mmap"); | |
494 | goto error_mmap; | |
a6352fd4 MD |
495 | } |
496 | ||
497 | shm_header->magic = SHM_MAGIC; | |
498 | shm_header->major = SHM_MAJOR; | |
499 | shm_header->major = SHM_MINOR; | |
500 | shm_header->bits_per_long = CAA_BITS_PER_LONG; | |
501 | shm_header->shm_size = shmsize; | |
502 | shm_header->shm_allocated = sizeof(struct shm_header); | |
503 | ||
431d5cf0 | 504 | align_shm(shm_header, __alignof__(struct channel)); |
a6352fd4 MD |
505 | chan = zalloc_shm(shm_header, sizeof(struct channel)); |
506 | if (!chan) | |
507 | goto destroy_shmem; | |
508 | set_shmp(shm_header->chan, chan); | |
509 | ||
510 | ret = channel_backend_init(&chan->backend, name, config, priv, | |
511 | subbuf_size, num_subbuf, shm_header); | |
852c2936 | 512 | if (ret) |
a6352fd4 | 513 | goto destroy_shmem; |
852c2936 MD |
514 | |
515 | chan->commit_count_mask = (~0UL >> chan->backend.num_subbuf_order); | |
a6352fd4 MD |
516 | //TODO |
517 | //chan->switch_timer_interval = usecs_to_jiffies(switch_timer_interval); | |
518 | //chan->read_timer_interval = usecs_to_jiffies(read_timer_interval); | |
a6352fd4 MD |
519 | //TODO |
520 | //init_waitqueue_head(&chan->read_wait); | |
521 | //init_waitqueue_head(&chan->hp_wait); | |
852c2936 MD |
522 | |
523 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) { | |
852c2936 MD |
524 | /* |
525 | * In case of non-hotplug cpu, if the ring-buffer is allocated | |
526 | * in early initcall, it will not be notified of secondary cpus. | |
527 | * In that off case, we need to allocate for all possible cpus. | |
528 | */ | |
852c2936 | 529 | for_each_possible_cpu(cpu) { |
a6352fd4 | 530 | struct lib_ring_buffer *buf = &shmp(chan->backend.buf)[cpu]; |
852c2936 MD |
531 | lib_ring_buffer_start_switch_timer(buf); |
532 | lib_ring_buffer_start_read_timer(buf); | |
852c2936 | 533 | } |
852c2936 | 534 | } else { |
a6352fd4 | 535 | struct lib_ring_buffer *buf = shmp(chan->backend.buf); |
852c2936 MD |
536 | |
537 | lib_ring_buffer_start_switch_timer(buf); | |
538 | lib_ring_buffer_start_read_timer(buf); | |
539 | } | |
540 | ||
431d5cf0 MD |
541 | handle->header = shm_header; |
542 | handle->shmfd = shmfd; | |
543 | return handle; | |
852c2936 | 544 | |
a6352fd4 | 545 | destroy_shmem: |
431d5cf0 MD |
546 | ret = munmap(shm_header, shmsize); |
547 | if (ret) { | |
548 | PERROR("umnmap"); | |
549 | assert(0); | |
a6352fd4 | 550 | } |
431d5cf0 MD |
551 | error_mmap: |
552 | error_ftruncate: | |
553 | error_unlink: | |
554 | ret = close(shmfd); | |
555 | if (ret) { | |
556 | PERROR("close"); | |
557 | assert(0); | |
558 | } | |
559 | error_shm_open: | |
560 | free(handle); | |
852c2936 MD |
561 | return NULL; |
562 | } | |
852c2936 MD |
563 | |
564 | static | |
431d5cf0 | 565 | void channel_release(struct shm_handle *handle) |
852c2936 | 566 | { |
431d5cf0 | 567 | channel_free(handle); |
852c2936 MD |
568 | } |
569 | ||
570 | /** | |
571 | * channel_destroy - Finalize, wait for q.s. and destroy channel. | |
572 | * @chan: channel to destroy | |
573 | * | |
574 | * Holds cpu hotplug. | |
431d5cf0 MD |
575 | * Call "destroy" callback, finalize channels, decrement the channel |
576 | * reference count. Note that when readers have completed data | |
577 | * consumption of finalized channels, get_subbuf() will return -ENODATA. | |
578 | * They should release their handle at that point. Returns the private | |
579 | * data pointer. | |
852c2936 | 580 | */ |
431d5cf0 | 581 | void *channel_destroy(struct shm_handle *handle) |
852c2936 | 582 | { |
431d5cf0 MD |
583 | struct shm_header *header = handle->header; |
584 | struct channel *chan = shmp(header->chan); | |
852c2936 MD |
585 | const struct lib_ring_buffer_config *config = chan->backend.config; |
586 | void *priv; | |
431d5cf0 | 587 | int cpu; |
852c2936 MD |
588 | |
589 | channel_unregister_notifiers(chan); | |
590 | ||
591 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) { | |
852c2936 | 592 | for_each_channel_cpu(cpu, chan) { |
a6352fd4 | 593 | struct lib_ring_buffer *buf = &shmp(chan->backend.buf)[cpu]; |
852c2936 MD |
594 | |
595 | if (config->cb.buffer_finalize) | |
596 | config->cb.buffer_finalize(buf, | |
597 | chan->backend.priv, | |
598 | cpu); | |
599 | if (buf->backend.allocated) | |
600 | lib_ring_buffer_switch_slow(buf, SWITCH_FLUSH); | |
601 | /* | |
602 | * Perform flush before writing to finalized. | |
603 | */ | |
a6352fd4 | 604 | cmm_smp_wmb(); |
14641deb | 605 | CMM_ACCESS_ONCE(buf->finalized) = 1; |
a6352fd4 | 606 | //wake_up_interruptible(&buf->read_wait); |
852c2936 MD |
607 | } |
608 | } else { | |
a6352fd4 | 609 | struct lib_ring_buffer *buf = shmp(chan->backend.buf); |
852c2936 MD |
610 | |
611 | if (config->cb.buffer_finalize) | |
612 | config->cb.buffer_finalize(buf, chan->backend.priv, -1); | |
613 | if (buf->backend.allocated) | |
614 | lib_ring_buffer_switch_slow(buf, SWITCH_FLUSH); | |
615 | /* | |
616 | * Perform flush before writing to finalized. | |
617 | */ | |
a6352fd4 | 618 | cmm_smp_wmb(); |
14641deb | 619 | CMM_ACCESS_ONCE(buf->finalized) = 1; |
a6352fd4 | 620 | //wake_up_interruptible(&buf->read_wait); |
852c2936 | 621 | } |
14641deb | 622 | CMM_ACCESS_ONCE(chan->finalized) = 1; |
a6352fd4 MD |
623 | //wake_up_interruptible(&chan->hp_wait); |
624 | //wake_up_interruptible(&chan->read_wait); | |
431d5cf0 MD |
625 | /* |
626 | * sessiond/consumer are keeping a reference on the shm file | |
627 | * descriptor directly. No need to refcount. | |
628 | */ | |
629 | channel_release(handle); | |
852c2936 MD |
630 | priv = chan->backend.priv; |
631 | return priv; | |
632 | } | |
852c2936 MD |
633 | |
634 | struct lib_ring_buffer *channel_get_ring_buffer( | |
635 | const struct lib_ring_buffer_config *config, | |
636 | struct channel *chan, int cpu) | |
637 | { | |
638 | if (config->alloc == RING_BUFFER_ALLOC_GLOBAL) | |
a6352fd4 | 639 | return shmp(chan->backend.buf); |
852c2936 | 640 | else |
a6352fd4 | 641 | return &shmp(chan->backend.buf)[cpu]; |
852c2936 | 642 | } |
852c2936 MD |
643 | |
644 | int lib_ring_buffer_open_read(struct lib_ring_buffer *buf) | |
645 | { | |
a6352fd4 | 646 | struct channel *chan = shmp(buf->backend.chan); |
852c2936 | 647 | |
a6352fd4 | 648 | if (uatomic_cmpxchg(&buf->active_readers, 0, 1) != 0) |
852c2936 | 649 | return -EBUSY; |
a6352fd4 | 650 | cmm_smp_mb(); |
852c2936 MD |
651 | return 0; |
652 | } | |
852c2936 MD |
653 | |
654 | void lib_ring_buffer_release_read(struct lib_ring_buffer *buf) | |
655 | { | |
a6352fd4 | 656 | struct channel *chan = shmp(buf->backend.chan); |
852c2936 | 657 | |
a6352fd4 MD |
658 | CHAN_WARN_ON(chan, uatomic_read(&buf->active_readers) != 1); |
659 | cmm_smp_mb(); | |
660 | uatomic_dec(&buf->active_readers); | |
852c2936 MD |
661 | } |
662 | ||
663 | /** | |
664 | * lib_ring_buffer_snapshot - save subbuffer position snapshot (for read) | |
665 | * @buf: ring buffer | |
666 | * @consumed: consumed count indicating the position where to read | |
667 | * @produced: produced count, indicates position when to stop reading | |
668 | * | |
669 | * Returns -ENODATA if buffer is finalized, -EAGAIN if there is currently no | |
670 | * data to read at consumed position, or 0 if the get operation succeeds. | |
852c2936 MD |
671 | */ |
672 | ||
673 | int lib_ring_buffer_snapshot(struct lib_ring_buffer *buf, | |
674 | unsigned long *consumed, unsigned long *produced) | |
675 | { | |
a6352fd4 | 676 | struct channel *chan = shmp(buf->backend.chan); |
852c2936 MD |
677 | const struct lib_ring_buffer_config *config = chan->backend.config; |
678 | unsigned long consumed_cur, write_offset; | |
679 | int finalized; | |
680 | ||
14641deb | 681 | finalized = CMM_ACCESS_ONCE(buf->finalized); |
852c2936 MD |
682 | /* |
683 | * Read finalized before counters. | |
684 | */ | |
a6352fd4 MD |
685 | cmm_smp_rmb(); |
686 | consumed_cur = uatomic_read(&buf->consumed); | |
852c2936 MD |
687 | /* |
688 | * No need to issue a memory barrier between consumed count read and | |
689 | * write offset read, because consumed count can only change | |
690 | * concurrently in overwrite mode, and we keep a sequence counter | |
691 | * identifier derived from the write offset to check we are getting | |
692 | * the same sub-buffer we are expecting (the sub-buffers are atomically | |
693 | * "tagged" upon writes, tags are checked upon read). | |
694 | */ | |
695 | write_offset = v_read(config, &buf->offset); | |
696 | ||
697 | /* | |
698 | * Check that we are not about to read the same subbuffer in | |
699 | * which the writer head is. | |
700 | */ | |
701 | if (subbuf_trunc(write_offset, chan) - subbuf_trunc(consumed_cur, chan) | |
702 | == 0) | |
703 | goto nodata; | |
704 | ||
705 | *consumed = consumed_cur; | |
706 | *produced = subbuf_trunc(write_offset, chan); | |
707 | ||
708 | return 0; | |
709 | ||
710 | nodata: | |
711 | /* | |
712 | * The memory barriers __wait_event()/wake_up_interruptible() take care | |
713 | * of "raw_spin_is_locked" memory ordering. | |
714 | */ | |
715 | if (finalized) | |
716 | return -ENODATA; | |
852c2936 MD |
717 | else |
718 | return -EAGAIN; | |
719 | } | |
852c2936 MD |
720 | |
721 | /** | |
722 | * lib_ring_buffer_put_snapshot - move consumed counter forward | |
723 | * @buf: ring buffer | |
724 | * @consumed_new: new consumed count value | |
725 | */ | |
726 | void lib_ring_buffer_move_consumer(struct lib_ring_buffer *buf, | |
727 | unsigned long consumed_new) | |
728 | { | |
729 | struct lib_ring_buffer_backend *bufb = &buf->backend; | |
a6352fd4 | 730 | struct channel *chan = shmp(bufb->chan); |
852c2936 MD |
731 | unsigned long consumed; |
732 | ||
a6352fd4 | 733 | CHAN_WARN_ON(chan, uatomic_read(&buf->active_readers) != 1); |
852c2936 MD |
734 | |
735 | /* | |
736 | * Only push the consumed value forward. | |
737 | * If the consumed cmpxchg fails, this is because we have been pushed by | |
738 | * the writer in flight recorder mode. | |
739 | */ | |
a6352fd4 | 740 | consumed = uatomic_read(&buf->consumed); |
852c2936 | 741 | while ((long) consumed - (long) consumed_new < 0) |
a6352fd4 MD |
742 | consumed = uatomic_cmpxchg(&buf->consumed, consumed, |
743 | consumed_new); | |
852c2936 | 744 | } |
852c2936 MD |
745 | |
746 | /** | |
747 | * lib_ring_buffer_get_subbuf - get exclusive access to subbuffer for reading | |
748 | * @buf: ring buffer | |
749 | * @consumed: consumed count indicating the position where to read | |
750 | * | |
751 | * Returns -ENODATA if buffer is finalized, -EAGAIN if there is currently no | |
752 | * data to read at consumed position, or 0 if the get operation succeeds. | |
852c2936 MD |
753 | */ |
754 | int lib_ring_buffer_get_subbuf(struct lib_ring_buffer *buf, | |
755 | unsigned long consumed) | |
756 | { | |
a6352fd4 | 757 | struct channel *chan = shmp(buf->backend.chan); |
852c2936 MD |
758 | const struct lib_ring_buffer_config *config = chan->backend.config; |
759 | unsigned long consumed_cur, consumed_idx, commit_count, write_offset; | |
760 | int ret; | |
761 | int finalized; | |
762 | ||
763 | retry: | |
14641deb | 764 | finalized = CMM_ACCESS_ONCE(buf->finalized); |
852c2936 MD |
765 | /* |
766 | * Read finalized before counters. | |
767 | */ | |
a6352fd4 MD |
768 | cmm_smp_rmb(); |
769 | consumed_cur = uatomic_read(&buf->consumed); | |
852c2936 | 770 | consumed_idx = subbuf_index(consumed, chan); |
a6352fd4 | 771 | commit_count = v_read(config, &shmp(buf->commit_cold)[consumed_idx].cc_sb); |
852c2936 MD |
772 | /* |
773 | * Make sure we read the commit count before reading the buffer | |
774 | * data and the write offset. Correct consumed offset ordering | |
775 | * wrt commit count is insured by the use of cmpxchg to update | |
776 | * the consumed offset. | |
852c2936 | 777 | */ |
a6352fd4 MD |
778 | /* |
779 | * Local rmb to match the remote wmb to read the commit count | |
780 | * before the buffer data and the write offset. | |
781 | */ | |
782 | cmm_smp_rmb(); | |
852c2936 MD |
783 | |
784 | write_offset = v_read(config, &buf->offset); | |
785 | ||
786 | /* | |
787 | * Check that the buffer we are getting is after or at consumed_cur | |
788 | * position. | |
789 | */ | |
790 | if ((long) subbuf_trunc(consumed, chan) | |
791 | - (long) subbuf_trunc(consumed_cur, chan) < 0) | |
792 | goto nodata; | |
793 | ||
794 | /* | |
795 | * Check that the subbuffer we are trying to consume has been | |
796 | * already fully committed. | |
797 | */ | |
798 | if (((commit_count - chan->backend.subbuf_size) | |
799 | & chan->commit_count_mask) | |
800 | - (buf_trunc(consumed_cur, chan) | |
801 | >> chan->backend.num_subbuf_order) | |
802 | != 0) | |
803 | goto nodata; | |
804 | ||
805 | /* | |
806 | * Check that we are not about to read the same subbuffer in | |
807 | * which the writer head is. | |
808 | */ | |
809 | if (subbuf_trunc(write_offset, chan) - subbuf_trunc(consumed_cur, chan) | |
810 | == 0) | |
811 | goto nodata; | |
812 | ||
813 | /* | |
814 | * Failure to get the subbuffer causes a busy-loop retry without going | |
815 | * to a wait queue. These are caused by short-lived race windows where | |
816 | * the writer is getting access to a subbuffer we were trying to get | |
817 | * access to. Also checks that the "consumed" buffer count we are | |
818 | * looking for matches the one contained in the subbuffer id. | |
819 | */ | |
820 | ret = update_read_sb_index(config, &buf->backend, &chan->backend, | |
821 | consumed_idx, buf_trunc_val(consumed, chan)); | |
822 | if (ret) | |
823 | goto retry; | |
824 | subbuffer_id_clear_noref(config, &buf->backend.buf_rsb.id); | |
825 | ||
826 | buf->get_subbuf_consumed = consumed; | |
827 | buf->get_subbuf = 1; | |
828 | ||
829 | return 0; | |
830 | ||
831 | nodata: | |
832 | /* | |
833 | * The memory barriers __wait_event()/wake_up_interruptible() take care | |
834 | * of "raw_spin_is_locked" memory ordering. | |
835 | */ | |
836 | if (finalized) | |
837 | return -ENODATA; | |
852c2936 MD |
838 | else |
839 | return -EAGAIN; | |
840 | } | |
852c2936 MD |
841 | |
842 | /** | |
843 | * lib_ring_buffer_put_subbuf - release exclusive subbuffer access | |
844 | * @buf: ring buffer | |
845 | */ | |
846 | void lib_ring_buffer_put_subbuf(struct lib_ring_buffer *buf) | |
847 | { | |
848 | struct lib_ring_buffer_backend *bufb = &buf->backend; | |
a6352fd4 | 849 | struct channel *chan = shmp(bufb->chan); |
852c2936 MD |
850 | const struct lib_ring_buffer_config *config = chan->backend.config; |
851 | unsigned long read_sb_bindex, consumed_idx, consumed; | |
852 | ||
a6352fd4 | 853 | CHAN_WARN_ON(chan, uatomic_read(&buf->active_readers) != 1); |
852c2936 MD |
854 | |
855 | if (!buf->get_subbuf) { | |
856 | /* | |
857 | * Reader puts a subbuffer it did not get. | |
858 | */ | |
859 | CHAN_WARN_ON(chan, 1); | |
860 | return; | |
861 | } | |
862 | consumed = buf->get_subbuf_consumed; | |
863 | buf->get_subbuf = 0; | |
864 | ||
865 | /* | |
866 | * Clear the records_unread counter. (overruns counter) | |
867 | * Can still be non-zero if a file reader simply grabbed the data | |
868 | * without using iterators. | |
869 | * Can be below zero if an iterator is used on a snapshot more than | |
870 | * once. | |
871 | */ | |
872 | read_sb_bindex = subbuffer_id_get_index(config, bufb->buf_rsb.id); | |
873 | v_add(config, v_read(config, | |
a6352fd4 | 874 | &shmp(bufb->array)[read_sb_bindex]->records_unread), |
852c2936 | 875 | &bufb->records_read); |
a6352fd4 | 876 | v_set(config, &shmp(bufb->array)[read_sb_bindex]->records_unread, 0); |
852c2936 MD |
877 | CHAN_WARN_ON(chan, config->mode == RING_BUFFER_OVERWRITE |
878 | && subbuffer_id_is_noref(config, bufb->buf_rsb.id)); | |
879 | subbuffer_id_set_noref(config, &bufb->buf_rsb.id); | |
880 | ||
881 | /* | |
882 | * Exchange the reader subbuffer with the one we put in its place in the | |
883 | * writer subbuffer table. Expect the original consumed count. If | |
884 | * update_read_sb_index fails, this is because the writer updated the | |
885 | * subbuffer concurrently. We should therefore keep the subbuffer we | |
886 | * currently have: it has become invalid to try reading this sub-buffer | |
887 | * consumed count value anyway. | |
888 | */ | |
889 | consumed_idx = subbuf_index(consumed, chan); | |
890 | update_read_sb_index(config, &buf->backend, &chan->backend, | |
891 | consumed_idx, buf_trunc_val(consumed, chan)); | |
892 | /* | |
893 | * update_read_sb_index return value ignored. Don't exchange sub-buffer | |
894 | * if the writer concurrently updated it. | |
895 | */ | |
896 | } | |
852c2936 MD |
897 | |
898 | /* | |
899 | * cons_offset is an iterator on all subbuffer offsets between the reader | |
900 | * position and the writer position. (inclusive) | |
901 | */ | |
902 | static | |
903 | void lib_ring_buffer_print_subbuffer_errors(struct lib_ring_buffer *buf, | |
904 | struct channel *chan, | |
905 | unsigned long cons_offset, | |
906 | int cpu) | |
907 | { | |
908 | const struct lib_ring_buffer_config *config = chan->backend.config; | |
909 | unsigned long cons_idx, commit_count, commit_count_sb; | |
910 | ||
911 | cons_idx = subbuf_index(cons_offset, chan); | |
a6352fd4 MD |
912 | commit_count = v_read(config, &shmp(buf->commit_hot)[cons_idx].cc); |
913 | commit_count_sb = v_read(config, &shmp(buf->commit_cold)[cons_idx].cc_sb); | |
852c2936 MD |
914 | |
915 | if (subbuf_offset(commit_count, chan) != 0) | |
a6352fd4 | 916 | ERRMSG("ring buffer %s, cpu %d: " |
852c2936 MD |
917 | "commit count in subbuffer %lu,\n" |
918 | "expecting multiples of %lu bytes\n" | |
919 | " [ %lu bytes committed, %lu bytes reader-visible ]\n", | |
920 | chan->backend.name, cpu, cons_idx, | |
921 | chan->backend.subbuf_size, | |
922 | commit_count, commit_count_sb); | |
923 | ||
a6352fd4 | 924 | ERRMSG("ring buffer: %s, cpu %d: %lu bytes committed\n", |
852c2936 MD |
925 | chan->backend.name, cpu, commit_count); |
926 | } | |
927 | ||
928 | static | |
929 | void lib_ring_buffer_print_buffer_errors(struct lib_ring_buffer *buf, | |
930 | struct channel *chan, | |
931 | void *priv, int cpu) | |
932 | { | |
933 | const struct lib_ring_buffer_config *config = chan->backend.config; | |
934 | unsigned long write_offset, cons_offset; | |
935 | ||
936 | /* | |
937 | * Can be called in the error path of allocation when | |
938 | * trans_channel_data is not yet set. | |
939 | */ | |
940 | if (!chan) | |
941 | return; | |
942 | /* | |
943 | * No need to order commit_count, write_offset and cons_offset reads | |
944 | * because we execute at teardown when no more writer nor reader | |
945 | * references are left. | |
946 | */ | |
947 | write_offset = v_read(config, &buf->offset); | |
a6352fd4 | 948 | cons_offset = uatomic_read(&buf->consumed); |
852c2936 | 949 | if (write_offset != cons_offset) |
a6352fd4 | 950 | ERRMSG("ring buffer %s, cpu %d: " |
852c2936 MD |
951 | "non-consumed data\n" |
952 | " [ %lu bytes written, %lu bytes read ]\n", | |
953 | chan->backend.name, cpu, write_offset, cons_offset); | |
954 | ||
a6352fd4 | 955 | for (cons_offset = uatomic_read(&buf->consumed); |
852c2936 MD |
956 | (long) (subbuf_trunc((unsigned long) v_read(config, &buf->offset), |
957 | chan) | |
958 | - cons_offset) > 0; | |
959 | cons_offset = subbuf_align(cons_offset, chan)) | |
960 | lib_ring_buffer_print_subbuffer_errors(buf, chan, cons_offset, | |
961 | cpu); | |
962 | } | |
963 | ||
964 | static | |
965 | void lib_ring_buffer_print_errors(struct channel *chan, | |
966 | struct lib_ring_buffer *buf, int cpu) | |
967 | { | |
968 | const struct lib_ring_buffer_config *config = chan->backend.config; | |
969 | void *priv = chan->backend.priv; | |
970 | ||
a6352fd4 | 971 | ERRMSG("ring buffer %s, cpu %d: %lu records written, " |
852c2936 MD |
972 | "%lu records overrun\n", |
973 | chan->backend.name, cpu, | |
974 | v_read(config, &buf->records_count), | |
975 | v_read(config, &buf->records_overrun)); | |
976 | ||
977 | if (v_read(config, &buf->records_lost_full) | |
978 | || v_read(config, &buf->records_lost_wrap) | |
979 | || v_read(config, &buf->records_lost_big)) | |
a6352fd4 | 980 | ERRMSG("ring buffer %s, cpu %d: records were lost. Caused by:\n" |
852c2936 MD |
981 | " [ %lu buffer full, %lu nest buffer wrap-around, " |
982 | "%lu event too big ]\n", | |
983 | chan->backend.name, cpu, | |
984 | v_read(config, &buf->records_lost_full), | |
985 | v_read(config, &buf->records_lost_wrap), | |
986 | v_read(config, &buf->records_lost_big)); | |
987 | ||
988 | lib_ring_buffer_print_buffer_errors(buf, chan, priv, cpu); | |
989 | } | |
990 | ||
991 | /* | |
992 | * lib_ring_buffer_switch_old_start: Populate old subbuffer header. | |
993 | * | |
994 | * Only executed when the buffer is finalized, in SWITCH_FLUSH. | |
995 | */ | |
996 | static | |
997 | void lib_ring_buffer_switch_old_start(struct lib_ring_buffer *buf, | |
998 | struct channel *chan, | |
999 | struct switch_offsets *offsets, | |
1000 | u64 tsc) | |
1001 | { | |
1002 | const struct lib_ring_buffer_config *config = chan->backend.config; | |
1003 | unsigned long oldidx = subbuf_index(offsets->old, chan); | |
1004 | unsigned long commit_count; | |
1005 | ||
1006 | config->cb.buffer_begin(buf, tsc, oldidx); | |
1007 | ||
1008 | /* | |
1009 | * Order all writes to buffer before the commit count update that will | |
1010 | * determine that the subbuffer is full. | |
1011 | */ | |
a6352fd4 | 1012 | cmm_smp_wmb(); |
852c2936 | 1013 | v_add(config, config->cb.subbuffer_header_size(), |
a6352fd4 MD |
1014 | &shmp(buf->commit_hot)[oldidx].cc); |
1015 | commit_count = v_read(config, &shmp(buf->commit_hot)[oldidx].cc); | |
852c2936 MD |
1016 | /* Check if the written buffer has to be delivered */ |
1017 | lib_ring_buffer_check_deliver(config, buf, chan, offsets->old, | |
1018 | commit_count, oldidx); | |
1019 | lib_ring_buffer_write_commit_counter(config, buf, chan, oldidx, | |
1020 | offsets->old, commit_count, | |
1021 | config->cb.subbuffer_header_size()); | |
1022 | } | |
1023 | ||
1024 | /* | |
1025 | * lib_ring_buffer_switch_old_end: switch old subbuffer | |
1026 | * | |
1027 | * Note : offset_old should never be 0 here. It is ok, because we never perform | |
1028 | * buffer switch on an empty subbuffer in SWITCH_ACTIVE mode. The caller | |
1029 | * increments the offset_old value when doing a SWITCH_FLUSH on an empty | |
1030 | * subbuffer. | |
1031 | */ | |
1032 | static | |
1033 | void lib_ring_buffer_switch_old_end(struct lib_ring_buffer *buf, | |
1034 | struct channel *chan, | |
1035 | struct switch_offsets *offsets, | |
1036 | u64 tsc) | |
1037 | { | |
1038 | const struct lib_ring_buffer_config *config = chan->backend.config; | |
1039 | unsigned long oldidx = subbuf_index(offsets->old - 1, chan); | |
1040 | unsigned long commit_count, padding_size, data_size; | |
1041 | ||
1042 | data_size = subbuf_offset(offsets->old - 1, chan) + 1; | |
1043 | padding_size = chan->backend.subbuf_size - data_size; | |
1044 | subbuffer_set_data_size(config, &buf->backend, oldidx, data_size); | |
1045 | ||
1046 | /* | |
1047 | * Order all writes to buffer before the commit count update that will | |
1048 | * determine that the subbuffer is full. | |
1049 | */ | |
a6352fd4 MD |
1050 | cmm_smp_wmb(); |
1051 | v_add(config, padding_size, &shmp(buf->commit_hot)[oldidx].cc); | |
1052 | commit_count = v_read(config, &shmp(buf->commit_hot)[oldidx].cc); | |
852c2936 MD |
1053 | lib_ring_buffer_check_deliver(config, buf, chan, offsets->old - 1, |
1054 | commit_count, oldidx); | |
1055 | lib_ring_buffer_write_commit_counter(config, buf, chan, oldidx, | |
1056 | offsets->old, commit_count, | |
1057 | padding_size); | |
1058 | } | |
1059 | ||
1060 | /* | |
1061 | * lib_ring_buffer_switch_new_start: Populate new subbuffer. | |
1062 | * | |
1063 | * This code can be executed unordered : writers may already have written to the | |
1064 | * sub-buffer before this code gets executed, caution. The commit makes sure | |
1065 | * that this code is executed before the deliver of this sub-buffer. | |
1066 | */ | |
1067 | static | |
1068 | void lib_ring_buffer_switch_new_start(struct lib_ring_buffer *buf, | |
1069 | struct channel *chan, | |
1070 | struct switch_offsets *offsets, | |
1071 | u64 tsc) | |
1072 | { | |
1073 | const struct lib_ring_buffer_config *config = chan->backend.config; | |
1074 | unsigned long beginidx = subbuf_index(offsets->begin, chan); | |
1075 | unsigned long commit_count; | |
1076 | ||
1077 | config->cb.buffer_begin(buf, tsc, beginidx); | |
1078 | ||
1079 | /* | |
1080 | * Order all writes to buffer before the commit count update that will | |
1081 | * determine that the subbuffer is full. | |
1082 | */ | |
a6352fd4 | 1083 | cmm_smp_wmb(); |
852c2936 | 1084 | v_add(config, config->cb.subbuffer_header_size(), |
a6352fd4 MD |
1085 | &shmp(buf->commit_hot)[beginidx].cc); |
1086 | commit_count = v_read(config, &shmp(buf->commit_hot)[beginidx].cc); | |
852c2936 MD |
1087 | /* Check if the written buffer has to be delivered */ |
1088 | lib_ring_buffer_check_deliver(config, buf, chan, offsets->begin, | |
1089 | commit_count, beginidx); | |
1090 | lib_ring_buffer_write_commit_counter(config, buf, chan, beginidx, | |
1091 | offsets->begin, commit_count, | |
1092 | config->cb.subbuffer_header_size()); | |
1093 | } | |
1094 | ||
1095 | /* | |
1096 | * lib_ring_buffer_switch_new_end: finish switching current subbuffer | |
1097 | * | |
1098 | * The only remaining threads could be the ones with pending commits. They will | |
1099 | * have to do the deliver themselves. | |
1100 | */ | |
1101 | static | |
1102 | void lib_ring_buffer_switch_new_end(struct lib_ring_buffer *buf, | |
1103 | struct channel *chan, | |
1104 | struct switch_offsets *offsets, | |
1105 | u64 tsc) | |
1106 | { | |
1107 | const struct lib_ring_buffer_config *config = chan->backend.config; | |
1108 | unsigned long endidx = subbuf_index(offsets->end - 1, chan); | |
1109 | unsigned long commit_count, padding_size, data_size; | |
1110 | ||
1111 | data_size = subbuf_offset(offsets->end - 1, chan) + 1; | |
1112 | padding_size = chan->backend.subbuf_size - data_size; | |
1113 | subbuffer_set_data_size(config, &buf->backend, endidx, data_size); | |
1114 | ||
1115 | /* | |
1116 | * Order all writes to buffer before the commit count update that will | |
1117 | * determine that the subbuffer is full. | |
1118 | */ | |
a6352fd4 MD |
1119 | cmm_smp_wmb(); |
1120 | v_add(config, padding_size, &shmp(buf->commit_hot)[endidx].cc); | |
1121 | commit_count = v_read(config, &shmp(buf->commit_hot)[endidx].cc); | |
852c2936 MD |
1122 | lib_ring_buffer_check_deliver(config, buf, chan, offsets->end - 1, |
1123 | commit_count, endidx); | |
1124 | lib_ring_buffer_write_commit_counter(config, buf, chan, endidx, | |
1125 | offsets->end, commit_count, | |
1126 | padding_size); | |
1127 | } | |
1128 | ||
1129 | /* | |
1130 | * Returns : | |
1131 | * 0 if ok | |
1132 | * !0 if execution must be aborted. | |
1133 | */ | |
1134 | static | |
1135 | int lib_ring_buffer_try_switch_slow(enum switch_mode mode, | |
1136 | struct lib_ring_buffer *buf, | |
1137 | struct channel *chan, | |
1138 | struct switch_offsets *offsets, | |
1139 | u64 *tsc) | |
1140 | { | |
1141 | const struct lib_ring_buffer_config *config = chan->backend.config; | |
1142 | unsigned long off; | |
1143 | ||
1144 | offsets->begin = v_read(config, &buf->offset); | |
1145 | offsets->old = offsets->begin; | |
1146 | offsets->switch_old_start = 0; | |
1147 | off = subbuf_offset(offsets->begin, chan); | |
1148 | ||
1149 | *tsc = config->cb.ring_buffer_clock_read(chan); | |
1150 | ||
1151 | /* | |
1152 | * Ensure we flush the header of an empty subbuffer when doing the | |
1153 | * finalize (SWITCH_FLUSH). This ensures that we end up knowing the | |
1154 | * total data gathering duration even if there were no records saved | |
1155 | * after the last buffer switch. | |
1156 | * In SWITCH_ACTIVE mode, switch the buffer when it contains events. | |
1157 | * SWITCH_ACTIVE only flushes the current subbuffer, dealing with end of | |
1158 | * subbuffer header as appropriate. | |
1159 | * The next record that reserves space will be responsible for | |
1160 | * populating the following subbuffer header. We choose not to populate | |
1161 | * the next subbuffer header here because we want to be able to use | |
a6352fd4 MD |
1162 | * SWITCH_ACTIVE for periodical buffer flush, which must |
1163 | * guarantee that all the buffer content (records and header | |
1164 | * timestamps) are visible to the reader. This is required for | |
1165 | * quiescence guarantees for the fusion merge. | |
852c2936 MD |
1166 | */ |
1167 | if (mode == SWITCH_FLUSH || off > 0) { | |
1168 | if (unlikely(off == 0)) { | |
1169 | /* | |
1170 | * The client does not save any header information. | |
1171 | * Don't switch empty subbuffer on finalize, because it | |
1172 | * is invalid to deliver a completely empty subbuffer. | |
1173 | */ | |
1174 | if (!config->cb.subbuffer_header_size()) | |
1175 | return -1; | |
1176 | /* | |
1177 | * Need to write the subbuffer start header on finalize. | |
1178 | */ | |
1179 | offsets->switch_old_start = 1; | |
1180 | } | |
1181 | offsets->begin = subbuf_align(offsets->begin, chan); | |
1182 | } else | |
1183 | return -1; /* we do not have to switch : buffer is empty */ | |
1184 | /* Note: old points to the next subbuf at offset 0 */ | |
1185 | offsets->end = offsets->begin; | |
1186 | return 0; | |
1187 | } | |
1188 | ||
1189 | /* | |
1190 | * Force a sub-buffer switch. This operation is completely reentrant : can be | |
1191 | * called while tracing is active with absolutely no lock held. | |
1192 | * | |
1193 | * Note, however, that as a v_cmpxchg is used for some atomic | |
1194 | * operations, this function must be called from the CPU which owns the buffer | |
1195 | * for a ACTIVE flush. | |
1196 | */ | |
1197 | void lib_ring_buffer_switch_slow(struct lib_ring_buffer *buf, enum switch_mode mode) | |
1198 | { | |
a6352fd4 | 1199 | struct channel *chan = shmp(buf->backend.chan); |
852c2936 MD |
1200 | const struct lib_ring_buffer_config *config = chan->backend.config; |
1201 | struct switch_offsets offsets; | |
1202 | unsigned long oldidx; | |
1203 | u64 tsc; | |
1204 | ||
1205 | offsets.size = 0; | |
1206 | ||
1207 | /* | |
1208 | * Perform retryable operations. | |
1209 | */ | |
1210 | do { | |
1211 | if (lib_ring_buffer_try_switch_slow(mode, buf, chan, &offsets, | |
1212 | &tsc)) | |
1213 | return; /* Switch not needed */ | |
1214 | } while (v_cmpxchg(config, &buf->offset, offsets.old, offsets.end) | |
1215 | != offsets.old); | |
1216 | ||
1217 | /* | |
1218 | * Atomically update last_tsc. This update races against concurrent | |
1219 | * atomic updates, but the race will always cause supplementary full TSC | |
1220 | * records, never the opposite (missing a full TSC record when it would | |
1221 | * be needed). | |
1222 | */ | |
1223 | save_last_tsc(config, buf, tsc); | |
1224 | ||
1225 | /* | |
1226 | * Push the reader if necessary | |
1227 | */ | |
1228 | lib_ring_buffer_reserve_push_reader(buf, chan, offsets.old); | |
1229 | ||
1230 | oldidx = subbuf_index(offsets.old, chan); | |
1231 | lib_ring_buffer_clear_noref(config, &buf->backend, oldidx); | |
1232 | ||
1233 | /* | |
1234 | * May need to populate header start on SWITCH_FLUSH. | |
1235 | */ | |
1236 | if (offsets.switch_old_start) { | |
1237 | lib_ring_buffer_switch_old_start(buf, chan, &offsets, tsc); | |
1238 | offsets.old += config->cb.subbuffer_header_size(); | |
1239 | } | |
1240 | ||
1241 | /* | |
1242 | * Switch old subbuffer. | |
1243 | */ | |
1244 | lib_ring_buffer_switch_old_end(buf, chan, &offsets, tsc); | |
1245 | } | |
852c2936 MD |
1246 | |
1247 | /* | |
1248 | * Returns : | |
1249 | * 0 if ok | |
1250 | * -ENOSPC if event size is too large for packet. | |
1251 | * -ENOBUFS if there is currently not enough space in buffer for the event. | |
1252 | * -EIO if data cannot be written into the buffer for any other reason. | |
1253 | */ | |
1254 | static | |
1255 | int lib_ring_buffer_try_reserve_slow(struct lib_ring_buffer *buf, | |
1256 | struct channel *chan, | |
1257 | struct switch_offsets *offsets, | |
1258 | struct lib_ring_buffer_ctx *ctx) | |
1259 | { | |
1260 | const struct lib_ring_buffer_config *config = chan->backend.config; | |
1261 | unsigned long reserve_commit_diff; | |
1262 | ||
1263 | offsets->begin = v_read(config, &buf->offset); | |
1264 | offsets->old = offsets->begin; | |
1265 | offsets->switch_new_start = 0; | |
1266 | offsets->switch_new_end = 0; | |
1267 | offsets->switch_old_end = 0; | |
1268 | offsets->pre_header_padding = 0; | |
1269 | ||
1270 | ctx->tsc = config->cb.ring_buffer_clock_read(chan); | |
1271 | if ((int64_t) ctx->tsc == -EIO) | |
1272 | return -EIO; | |
1273 | ||
1274 | if (last_tsc_overflow(config, buf, ctx->tsc)) | |
1275 | ctx->rflags |= RING_BUFFER_RFLAG_FULL_TSC; | |
1276 | ||
1277 | if (unlikely(subbuf_offset(offsets->begin, ctx->chan) == 0)) { | |
1278 | offsets->switch_new_start = 1; /* For offsets->begin */ | |
1279 | } else { | |
1280 | offsets->size = config->cb.record_header_size(config, chan, | |
1281 | offsets->begin, | |
1282 | &offsets->pre_header_padding, | |
1283 | ctx); | |
1284 | offsets->size += | |
1285 | lib_ring_buffer_align(offsets->begin + offsets->size, | |
1286 | ctx->largest_align) | |
1287 | + ctx->data_size; | |
1288 | if (unlikely(subbuf_offset(offsets->begin, chan) + | |
1289 | offsets->size > chan->backend.subbuf_size)) { | |
1290 | offsets->switch_old_end = 1; /* For offsets->old */ | |
1291 | offsets->switch_new_start = 1; /* For offsets->begin */ | |
1292 | } | |
1293 | } | |
1294 | if (unlikely(offsets->switch_new_start)) { | |
1295 | unsigned long sb_index; | |
1296 | ||
1297 | /* | |
1298 | * We are typically not filling the previous buffer completely. | |
1299 | */ | |
1300 | if (likely(offsets->switch_old_end)) | |
1301 | offsets->begin = subbuf_align(offsets->begin, chan); | |
1302 | offsets->begin = offsets->begin | |
1303 | + config->cb.subbuffer_header_size(); | |
1304 | /* Test new buffer integrity */ | |
1305 | sb_index = subbuf_index(offsets->begin, chan); | |
1306 | reserve_commit_diff = | |
1307 | (buf_trunc(offsets->begin, chan) | |
1308 | >> chan->backend.num_subbuf_order) | |
1309 | - ((unsigned long) v_read(config, | |
a6352fd4 | 1310 | &shmp(buf->commit_cold)[sb_index].cc_sb) |
852c2936 MD |
1311 | & chan->commit_count_mask); |
1312 | if (likely(reserve_commit_diff == 0)) { | |
1313 | /* Next subbuffer not being written to. */ | |
1314 | if (unlikely(config->mode != RING_BUFFER_OVERWRITE && | |
1315 | subbuf_trunc(offsets->begin, chan) | |
1316 | - subbuf_trunc((unsigned long) | |
a6352fd4 | 1317 | uatomic_read(&buf->consumed), chan) |
852c2936 MD |
1318 | >= chan->backend.buf_size)) { |
1319 | /* | |
1320 | * We do not overwrite non consumed buffers | |
1321 | * and we are full : record is lost. | |
1322 | */ | |
1323 | v_inc(config, &buf->records_lost_full); | |
1324 | return -ENOBUFS; | |
1325 | } else { | |
1326 | /* | |
1327 | * Next subbuffer not being written to, and we | |
1328 | * are either in overwrite mode or the buffer is | |
1329 | * not full. It's safe to write in this new | |
1330 | * subbuffer. | |
1331 | */ | |
1332 | } | |
1333 | } else { | |
1334 | /* | |
1335 | * Next subbuffer reserve offset does not match the | |
1336 | * commit offset. Drop record in producer-consumer and | |
1337 | * overwrite mode. Caused by either a writer OOPS or too | |
1338 | * many nested writes over a reserve/commit pair. | |
1339 | */ | |
1340 | v_inc(config, &buf->records_lost_wrap); | |
1341 | return -EIO; | |
1342 | } | |
1343 | offsets->size = | |
1344 | config->cb.record_header_size(config, chan, | |
1345 | offsets->begin, | |
1346 | &offsets->pre_header_padding, | |
1347 | ctx); | |
1348 | offsets->size += | |
1349 | lib_ring_buffer_align(offsets->begin + offsets->size, | |
1350 | ctx->largest_align) | |
1351 | + ctx->data_size; | |
1352 | if (unlikely(subbuf_offset(offsets->begin, chan) | |
1353 | + offsets->size > chan->backend.subbuf_size)) { | |
1354 | /* | |
1355 | * Record too big for subbuffers, report error, don't | |
1356 | * complete the sub-buffer switch. | |
1357 | */ | |
1358 | v_inc(config, &buf->records_lost_big); | |
1359 | return -ENOSPC; | |
1360 | } else { | |
1361 | /* | |
1362 | * We just made a successful buffer switch and the | |
1363 | * record fits in the new subbuffer. Let's write. | |
1364 | */ | |
1365 | } | |
1366 | } else { | |
1367 | /* | |
1368 | * Record fits in the current buffer and we are not on a switch | |
1369 | * boundary. It's safe to write. | |
1370 | */ | |
1371 | } | |
1372 | offsets->end = offsets->begin + offsets->size; | |
1373 | ||
1374 | if (unlikely(subbuf_offset(offsets->end, chan) == 0)) { | |
1375 | /* | |
1376 | * The offset_end will fall at the very beginning of the next | |
1377 | * subbuffer. | |
1378 | */ | |
1379 | offsets->switch_new_end = 1; /* For offsets->begin */ | |
1380 | } | |
1381 | return 0; | |
1382 | } | |
1383 | ||
1384 | /** | |
1385 | * lib_ring_buffer_reserve_slow - Atomic slot reservation in a buffer. | |
1386 | * @ctx: ring buffer context. | |
1387 | * | |
1388 | * Return : -NOBUFS if not enough space, -ENOSPC if event size too large, | |
1389 | * -EIO for other errors, else returns 0. | |
1390 | * It will take care of sub-buffer switching. | |
1391 | */ | |
1392 | int lib_ring_buffer_reserve_slow(struct lib_ring_buffer_ctx *ctx) | |
1393 | { | |
1394 | struct channel *chan = ctx->chan; | |
1395 | const struct lib_ring_buffer_config *config = chan->backend.config; | |
1396 | struct lib_ring_buffer *buf; | |
1397 | struct switch_offsets offsets; | |
1398 | int ret; | |
1399 | ||
1400 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) | |
a6352fd4 | 1401 | buf = &shmp(chan->backend.buf)[ctx->cpu]; |
852c2936 | 1402 | else |
a6352fd4 | 1403 | buf = shmp(chan->backend.buf); |
852c2936 MD |
1404 | ctx->buf = buf; |
1405 | ||
1406 | offsets.size = 0; | |
1407 | ||
1408 | do { | |
1409 | ret = lib_ring_buffer_try_reserve_slow(buf, chan, &offsets, | |
1410 | ctx); | |
1411 | if (unlikely(ret)) | |
1412 | return ret; | |
1413 | } while (unlikely(v_cmpxchg(config, &buf->offset, offsets.old, | |
1414 | offsets.end) | |
1415 | != offsets.old)); | |
1416 | ||
1417 | /* | |
1418 | * Atomically update last_tsc. This update races against concurrent | |
1419 | * atomic updates, but the race will always cause supplementary full TSC | |
1420 | * records, never the opposite (missing a full TSC record when it would | |
1421 | * be needed). | |
1422 | */ | |
1423 | save_last_tsc(config, buf, ctx->tsc); | |
1424 | ||
1425 | /* | |
1426 | * Push the reader if necessary | |
1427 | */ | |
1428 | lib_ring_buffer_reserve_push_reader(buf, chan, offsets.end - 1); | |
1429 | ||
1430 | /* | |
1431 | * Clear noref flag for this subbuffer. | |
1432 | */ | |
1433 | lib_ring_buffer_clear_noref(config, &buf->backend, | |
1434 | subbuf_index(offsets.end - 1, chan)); | |
1435 | ||
1436 | /* | |
1437 | * Switch old subbuffer if needed. | |
1438 | */ | |
1439 | if (unlikely(offsets.switch_old_end)) { | |
1440 | lib_ring_buffer_clear_noref(config, &buf->backend, | |
1441 | subbuf_index(offsets.old - 1, chan)); | |
1442 | lib_ring_buffer_switch_old_end(buf, chan, &offsets, ctx->tsc); | |
1443 | } | |
1444 | ||
1445 | /* | |
1446 | * Populate new subbuffer. | |
1447 | */ | |
1448 | if (unlikely(offsets.switch_new_start)) | |
1449 | lib_ring_buffer_switch_new_start(buf, chan, &offsets, ctx->tsc); | |
1450 | ||
1451 | if (unlikely(offsets.switch_new_end)) | |
1452 | lib_ring_buffer_switch_new_end(buf, chan, &offsets, ctx->tsc); | |
1453 | ||
1454 | ctx->slot_size = offsets.size; | |
1455 | ctx->pre_offset = offsets.begin; | |
1456 | ctx->buf_offset = offsets.begin + offsets.pre_header_padding; | |
1457 | return 0; | |
1458 | } |