Commit | Line | Data |
---|---|---|
852c2936 MD |
1 | /* |
2 | * ring_buffer_backend.c | |
3 | * | |
4 | * Copyright (C) 2005-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
5 | * | |
6 | * Dual LGPL v2.1/GPL v2 license. | |
7 | */ | |
8 | ||
14641deb MD |
9 | #include <urcu/arch.h> |
10 | ||
11 | #include "ust/core.h" | |
12 | ||
4931a13e MD |
13 | #include "config.h" |
14 | #include "backend.h" | |
15 | #include "frontend.h" | |
a6352fd4 | 16 | #include "smp.h" |
852c2936 MD |
17 | |
18 | /** | |
19 | * lib_ring_buffer_backend_allocate - allocate a channel buffer | |
20 | * @config: ring buffer instance configuration | |
21 | * @buf: the buffer struct | |
22 | * @size: total size of the buffer | |
23 | * @num_subbuf: number of subbuffers | |
24 | * @extra_reader_sb: need extra subbuffer for reader | |
25 | */ | |
26 | static | |
27 | int lib_ring_buffer_backend_allocate(const struct lib_ring_buffer_config *config, | |
28 | struct lib_ring_buffer_backend *bufb, | |
29 | size_t size, size_t num_subbuf, | |
a6352fd4 MD |
30 | int extra_reader_sb, |
31 | struct shm_header *shm_header) | |
852c2936 | 32 | { |
a6352fd4 | 33 | struct channel_backend *chanb = &shmp(bufb->chan)->backend; |
852c2936 MD |
34 | unsigned long subbuf_size, mmap_offset = 0; |
35 | unsigned long num_subbuf_alloc; | |
852c2936 MD |
36 | unsigned long i; |
37 | ||
852c2936 MD |
38 | subbuf_size = chanb->subbuf_size; |
39 | num_subbuf_alloc = num_subbuf; | |
40 | ||
a6352fd4 | 41 | if (extra_reader_sb) |
852c2936 | 42 | num_subbuf_alloc++; |
852c2936 | 43 | |
a6352fd4 MD |
44 | set_shmp(bufb->array, zalloc_shm(shm_header, |
45 | sizeof(*bufb->array) * num_subbuf_alloc)); | |
46 | if (unlikely(!shmp(bufb->array))) | |
852c2936 MD |
47 | goto array_error; |
48 | ||
a6352fd4 MD |
49 | set_shmp(bufb->memory_map, zalloc_shm(shm_header, |
50 | subbuf_size * num_subbuf_alloc)); | |
51 | if (unlikely(!shmp(bufb->memory_map))) | |
52 | goto memory_map_error; | |
852c2936 MD |
53 | |
54 | /* Allocate backend pages array elements */ | |
55 | for (i = 0; i < num_subbuf_alloc; i++) { | |
a6352fd4 MD |
56 | set_shmp(bufb->array[i], |
57 | zalloc_shm(shm_header, | |
852c2936 | 58 | sizeof(struct lib_ring_buffer_backend_pages) + |
a6352fd4 MD |
59 | subbuf_size)); |
60 | if (!shmp(bufb->array[i])) | |
852c2936 MD |
61 | goto free_array; |
62 | } | |
63 | ||
64 | /* Allocate write-side subbuffer table */ | |
a6352fd4 | 65 | bufb->buf_wsb = zalloc_shm(shm_header, |
852c2936 | 66 | sizeof(struct lib_ring_buffer_backend_subbuffer) |
14641deb | 67 | * num_subbuf); |
a6352fd4 | 68 | if (unlikely(!shmp(bufb->buf_wsb))) |
852c2936 MD |
69 | goto free_array; |
70 | ||
71 | for (i = 0; i < num_subbuf; i++) | |
a6352fd4 | 72 | shmp(bufb->buf_wsb)[i].id = subbuffer_id(config, 0, 1, i); |
852c2936 MD |
73 | |
74 | /* Assign read-side subbuffer table */ | |
75 | if (extra_reader_sb) | |
76 | bufb->buf_rsb.id = subbuffer_id(config, 0, 1, | |
77 | num_subbuf_alloc - 1); | |
78 | else | |
79 | bufb->buf_rsb.id = subbuffer_id(config, 0, 1, 0); | |
80 | ||
81 | /* Assign pages to page index */ | |
82 | for (i = 0; i < num_subbuf_alloc; i++) { | |
a6352fd4 MD |
83 | set_shmp(shmp(bufb->array)[i]->p, |
84 | &shmp(bufb->memory_map)[i * subbuf_size]); | |
852c2936 | 85 | if (config->output == RING_BUFFER_MMAP) { |
a6352fd4 | 86 | shmp(bufb->array)[i]->mmap_offset = mmap_offset; |
852c2936 MD |
87 | mmap_offset += subbuf_size; |
88 | } | |
89 | } | |
90 | ||
852c2936 MD |
91 | return 0; |
92 | ||
93 | free_array: | |
a6352fd4 MD |
94 | /* bufb->array[i] will be freed by shm teardown */ |
95 | memory_map_error: | |
96 | /* bufb->array will be freed by shm teardown */ | |
852c2936 | 97 | array_error: |
852c2936 MD |
98 | return -ENOMEM; |
99 | } | |
100 | ||
101 | int lib_ring_buffer_backend_create(struct lib_ring_buffer_backend *bufb, | |
a6352fd4 MD |
102 | struct channel_backend *chanb, int cpu, |
103 | struct shm_header *shm_header) | |
852c2936 MD |
104 | { |
105 | const struct lib_ring_buffer_config *config = chanb->config; | |
106 | ||
a6352fd4 | 107 | set_shmp(&bufb->chan, caa_container_of(chanb, struct channel, backend)); |
852c2936 MD |
108 | bufb->cpu = cpu; |
109 | ||
110 | return lib_ring_buffer_backend_allocate(config, bufb, chanb->buf_size, | |
111 | chanb->num_subbuf, | |
a6352fd4 MD |
112 | chanb->extra_reader_sb, |
113 | shm_header); | |
852c2936 MD |
114 | } |
115 | ||
116 | void lib_ring_buffer_backend_free(struct lib_ring_buffer_backend *bufb) | |
117 | { | |
a6352fd4 MD |
118 | /* bufb->buf_wsb will be freed by shm teardown */ |
119 | /* bufb->array[i] will be freed by shm teardown */ | |
120 | /* bufb->array will be freed by shm teardown */ | |
852c2936 MD |
121 | bufb->allocated = 0; |
122 | } | |
123 | ||
124 | void lib_ring_buffer_backend_reset(struct lib_ring_buffer_backend *bufb) | |
125 | { | |
a6352fd4 | 126 | struct channel_backend *chanb = &shmp(bufb->chan)->backend; |
852c2936 MD |
127 | const struct lib_ring_buffer_config *config = chanb->config; |
128 | unsigned long num_subbuf_alloc; | |
129 | unsigned int i; | |
130 | ||
131 | num_subbuf_alloc = chanb->num_subbuf; | |
132 | if (chanb->extra_reader_sb) | |
133 | num_subbuf_alloc++; | |
134 | ||
135 | for (i = 0; i < chanb->num_subbuf; i++) | |
a6352fd4 | 136 | shmp(bufb->buf_wsb)[i].id = subbuffer_id(config, 0, 1, i); |
852c2936 MD |
137 | if (chanb->extra_reader_sb) |
138 | bufb->buf_rsb.id = subbuffer_id(config, 0, 1, | |
139 | num_subbuf_alloc - 1); | |
140 | else | |
141 | bufb->buf_rsb.id = subbuffer_id(config, 0, 1, 0); | |
142 | ||
143 | for (i = 0; i < num_subbuf_alloc; i++) { | |
144 | /* Don't reset mmap_offset */ | |
a6352fd4 MD |
145 | v_set(config, &shmp(bufb->array)[i]->records_commit, 0); |
146 | v_set(config, &shmp(bufb->array)[i]->records_unread, 0); | |
147 | shmp(bufb->array)[i]->data_size = 0; | |
852c2936 MD |
148 | /* Don't reset backend page and virt addresses */ |
149 | } | |
150 | /* Don't reset num_pages_per_subbuf, cpu, allocated */ | |
151 | v_set(config, &bufb->records_read, 0); | |
152 | } | |
153 | ||
154 | /* | |
155 | * The frontend is responsible for also calling ring_buffer_backend_reset for | |
156 | * each buffer when calling channel_backend_reset. | |
157 | */ | |
158 | void channel_backend_reset(struct channel_backend *chanb) | |
159 | { | |
14641deb | 160 | struct channel *chan = caa_container_of(chanb, struct channel, backend); |
852c2936 MD |
161 | const struct lib_ring_buffer_config *config = chanb->config; |
162 | ||
163 | /* | |
164 | * Don't reset buf_size, subbuf_size, subbuf_size_order, | |
165 | * num_subbuf_order, buf_size_order, extra_reader_sb, num_subbuf, | |
166 | * priv, notifiers, config, cpumask and name. | |
167 | */ | |
168 | chanb->start_tsc = config->cb.ring_buffer_clock_read(chan); | |
169 | } | |
170 | ||
852c2936 MD |
171 | /** |
172 | * channel_backend_init - initialize a channel backend | |
173 | * @chanb: channel backend | |
174 | * @name: channel name | |
175 | * @config: client ring buffer configuration | |
176 | * @priv: client private data | |
177 | * @parent: dentry of parent directory, %NULL for root directory | |
178 | * @subbuf_size: size of sub-buffers (> PAGE_SIZE, power of 2) | |
179 | * @num_subbuf: number of sub-buffers (power of 2) | |
a6352fd4 | 180 | * @shm_header: shared memory header |
852c2936 MD |
181 | * |
182 | * Returns channel pointer if successful, %NULL otherwise. | |
183 | * | |
184 | * Creates per-cpu channel buffers using the sizes and attributes | |
185 | * specified. The created channel buffer files will be named | |
186 | * name_0...name_N-1. File permissions will be %S_IRUSR. | |
187 | * | |
188 | * Called with CPU hotplug disabled. | |
189 | */ | |
190 | int channel_backend_init(struct channel_backend *chanb, | |
191 | const char *name, | |
192 | const struct lib_ring_buffer_config *config, | |
a6352fd4 MD |
193 | void *priv, size_t subbuf_size, size_t num_subbuf, |
194 | struct shm_header *shm_header) | |
852c2936 | 195 | { |
14641deb | 196 | struct channel *chan = caa_container_of(chanb, struct channel, backend); |
852c2936 MD |
197 | unsigned int i; |
198 | int ret; | |
199 | ||
200 | if (!name) | |
201 | return -EPERM; | |
202 | ||
203 | if (!(subbuf_size && num_subbuf)) | |
204 | return -EPERM; | |
205 | ||
206 | /* Check that the subbuffer size is larger than a page. */ | |
207 | if (subbuf_size < PAGE_SIZE) | |
208 | return -EINVAL; | |
209 | ||
210 | /* | |
211 | * Make sure the number of subbuffers and subbuffer size are power of 2. | |
212 | */ | |
213 | CHAN_WARN_ON(chanb, hweight32(subbuf_size) != 1); | |
214 | CHAN_WARN_ON(chanb, hweight32(num_subbuf) != 1); | |
215 | ||
216 | ret = subbuffer_id_check_index(config, num_subbuf); | |
217 | if (ret) | |
218 | return ret; | |
219 | ||
220 | chanb->priv = priv; | |
221 | chanb->buf_size = num_subbuf * subbuf_size; | |
222 | chanb->subbuf_size = subbuf_size; | |
223 | chanb->buf_size_order = get_count_order(chanb->buf_size); | |
224 | chanb->subbuf_size_order = get_count_order(subbuf_size); | |
225 | chanb->num_subbuf_order = get_count_order(num_subbuf); | |
226 | chanb->extra_reader_sb = | |
227 | (config->mode == RING_BUFFER_OVERWRITE) ? 1 : 0; | |
228 | chanb->num_subbuf = num_subbuf; | |
a6352fd4 MD |
229 | strncpy(chanb->name, name, NAME_MAX); |
230 | chanb->name[NAME_MAX - 1] = '\0'; | |
852c2936 MD |
231 | chanb->config = config; |
232 | ||
233 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) { | |
a6352fd4 MD |
234 | struct lib_ring_buffer *buf; |
235 | size_t alloc_size; | |
852c2936 | 236 | |
852c2936 | 237 | /* Allocating the buffer per-cpu structures */ |
a6352fd4 MD |
238 | alloc_size = sizeof(struct lib_ring_buffer); |
239 | buf = zalloc_shm(shm_header, alloc_size * num_possible_cpus()); | |
240 | if (!buf) | |
241 | goto end; | |
242 | set_shmp(chanb->buf, buf); | |
852c2936 MD |
243 | |
244 | /* | |
a6352fd4 | 245 | * We need to allocate for all possible cpus. |
852c2936 | 246 | */ |
852c2936 | 247 | for_each_possible_cpu(i) { |
a6352fd4 MD |
248 | ret = lib_ring_buffer_create(&shmp(chanb->buf)[i], |
249 | chanb, i, shm_header); | |
852c2936 MD |
250 | if (ret) |
251 | goto free_bufs; /* cpu hotplug locked */ | |
252 | } | |
852c2936 | 253 | } else { |
a6352fd4 MD |
254 | struct lib_ring_buffer *buf; |
255 | size_t alloc_size; | |
256 | ||
257 | alloc_size = sizeof(struct lib_ring_buffer); | |
258 | chanb->buf = zmalloc(sizeof(struct lib_ring_buffer)); | |
259 | buf = zalloc_shm(shm_header, alloc_size); | |
260 | if (!buf) | |
261 | goto end; | |
262 | set_shmp(chanb->buf, buf); | |
263 | ret = lib_ring_buffer_create(shmp(chanb->buf), chanb, -1, | |
264 | shm_header); | |
852c2936 MD |
265 | if (ret) |
266 | goto free_bufs; | |
267 | } | |
268 | chanb->start_tsc = config->cb.ring_buffer_clock_read(chan); | |
269 | ||
270 | return 0; | |
271 | ||
272 | free_bufs: | |
273 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) { | |
274 | for_each_possible_cpu(i) { | |
a6352fd4 | 275 | struct lib_ring_buffer *buf = &shmp(chanb->buf)[i]; |
852c2936 MD |
276 | |
277 | if (!buf->backend.allocated) | |
278 | continue; | |
279 | lib_ring_buffer_free(buf); | |
280 | } | |
a6352fd4 MD |
281 | } |
282 | /* We only free the buffer data upon shm teardown */ | |
283 | end: | |
852c2936 MD |
284 | return -ENOMEM; |
285 | } | |
286 | ||
852c2936 MD |
287 | /** |
288 | * channel_backend_free - destroy the channel | |
289 | * @chan: the channel | |
290 | * | |
291 | * Destroy all channel buffers and frees the channel. | |
292 | */ | |
293 | void channel_backend_free(struct channel_backend *chanb) | |
294 | { | |
295 | const struct lib_ring_buffer_config *config = chanb->config; | |
296 | unsigned int i; | |
297 | ||
298 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) { | |
299 | for_each_possible_cpu(i) { | |
a6352fd4 | 300 | struct lib_ring_buffer *buf = &shmp(chanb->buf)[i]; |
852c2936 MD |
301 | |
302 | if (!buf->backend.allocated) | |
303 | continue; | |
304 | lib_ring_buffer_free(buf); | |
305 | } | |
852c2936 | 306 | } else { |
a6352fd4 | 307 | struct lib_ring_buffer *buf = shmp(chanb->buf); |
852c2936 MD |
308 | |
309 | CHAN_WARN_ON(chanb, !buf->backend.allocated); | |
310 | lib_ring_buffer_free(buf); | |
852c2936 | 311 | } |
a6352fd4 | 312 | /* We only free the buffer data upon shm teardown */ |
852c2936 MD |
313 | } |
314 | ||
852c2936 MD |
315 | /** |
316 | * lib_ring_buffer_read - read data from ring_buffer_buffer. | |
317 | * @bufb : buffer backend | |
318 | * @offset : offset within the buffer | |
319 | * @dest : destination address | |
320 | * @len : length to copy to destination | |
321 | * | |
322 | * Should be protected by get_subbuf/put_subbuf. | |
323 | * Returns the length copied. | |
324 | */ | |
325 | size_t lib_ring_buffer_read(struct lib_ring_buffer_backend *bufb, size_t offset, | |
326 | void *dest, size_t len) | |
327 | { | |
a6352fd4 | 328 | struct channel_backend *chanb = &shmp(bufb->chan)->backend; |
852c2936 | 329 | const struct lib_ring_buffer_config *config = chanb->config; |
a6352fd4 | 330 | ssize_t orig_len; |
852c2936 MD |
331 | struct lib_ring_buffer_backend_pages *rpages; |
332 | unsigned long sb_bindex, id; | |
333 | ||
334 | orig_len = len; | |
335 | offset &= chanb->buf_size - 1; | |
a6352fd4 | 336 | |
852c2936 MD |
337 | if (unlikely(!len)) |
338 | return 0; | |
a6352fd4 MD |
339 | id = bufb->buf_rsb.id; |
340 | sb_bindex = subbuffer_id_get_index(config, id); | |
341 | rpages = shmp(bufb->array)[sb_bindex]; | |
342 | /* | |
343 | * Underlying layer should never ask for reads across | |
344 | * subbuffers. | |
345 | */ | |
346 | CHAN_WARN_ON(chanb, offset >= chanb->buf_size); | |
347 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE | |
348 | && subbuffer_id_is_noref(config, id)); | |
349 | memcpy(dest, shmp(rpages->p) + (offset & ~(chanb->subbuf_size - 1)), len); | |
852c2936 MD |
350 | return orig_len; |
351 | } | |
852c2936 | 352 | |
852c2936 MD |
353 | /** |
354 | * lib_ring_buffer_read_cstr - read a C-style string from ring_buffer. | |
355 | * @bufb : buffer backend | |
356 | * @offset : offset within the buffer | |
357 | * @dest : destination address | |
358 | * @len : destination's length | |
359 | * | |
360 | * return string's length | |
361 | * Should be protected by get_subbuf/put_subbuf. | |
362 | */ | |
363 | int lib_ring_buffer_read_cstr(struct lib_ring_buffer_backend *bufb, size_t offset, | |
364 | void *dest, size_t len) | |
365 | { | |
a6352fd4 | 366 | struct channel_backend *chanb = &shmp(bufb->chan)->backend; |
852c2936 | 367 | const struct lib_ring_buffer_config *config = chanb->config; |
a6352fd4 | 368 | ssize_t string_len, orig_offset; |
852c2936 MD |
369 | char *str; |
370 | struct lib_ring_buffer_backend_pages *rpages; | |
371 | unsigned long sb_bindex, id; | |
372 | ||
373 | offset &= chanb->buf_size - 1; | |
852c2936 | 374 | orig_offset = offset; |
852c2936 MD |
375 | id = bufb->buf_rsb.id; |
376 | sb_bindex = subbuffer_id_get_index(config, id); | |
a6352fd4 MD |
377 | rpages = shmp(bufb->array)[sb_bindex]; |
378 | /* | |
379 | * Underlying layer should never ask for reads across | |
380 | * subbuffers. | |
381 | */ | |
382 | CHAN_WARN_ON(chanb, offset >= chanb->buf_size); | |
852c2936 MD |
383 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE |
384 | && subbuffer_id_is_noref(config, id)); | |
a6352fd4 MD |
385 | str = (char *)shmp(rpages->p) + (offset & ~(chanb->subbuf_size - 1)); |
386 | string_len = strnlen(str, len); | |
387 | if (dest && len) { | |
388 | memcpy(dest, str, string_len); | |
389 | ((char *)dest)[0] = 0; | |
390 | } | |
391 | return offset - orig_offset; | |
852c2936 | 392 | } |
852c2936 MD |
393 | |
394 | /** | |
395 | * lib_ring_buffer_read_offset_address - get address of a buffer location | |
396 | * @bufb : buffer backend | |
397 | * @offset : offset within the buffer. | |
398 | * | |
399 | * Return the address where a given offset is located (for read). | |
400 | * Should be used to get the current subbuffer header pointer. Given we know | |
401 | * it's never on a page boundary, it's safe to write directly to this address, | |
402 | * as long as the write is never bigger than a page size. | |
403 | */ | |
404 | void *lib_ring_buffer_read_offset_address(struct lib_ring_buffer_backend *bufb, | |
405 | size_t offset) | |
406 | { | |
852c2936 | 407 | struct lib_ring_buffer_backend_pages *rpages; |
a6352fd4 | 408 | struct channel_backend *chanb = &shmp(bufb->chan)->backend; |
852c2936 MD |
409 | const struct lib_ring_buffer_config *config = chanb->config; |
410 | unsigned long sb_bindex, id; | |
411 | ||
412 | offset &= chanb->buf_size - 1; | |
852c2936 MD |
413 | id = bufb->buf_rsb.id; |
414 | sb_bindex = subbuffer_id_get_index(config, id); | |
a6352fd4 | 415 | rpages = shmp(bufb->array)[sb_bindex]; |
852c2936 MD |
416 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE |
417 | && subbuffer_id_is_noref(config, id)); | |
a6352fd4 | 418 | return shmp(rpages->p) + (offset & ~(chanb->subbuf_size - 1)); |
852c2936 | 419 | } |
852c2936 MD |
420 | |
421 | /** | |
422 | * lib_ring_buffer_offset_address - get address of a location within the buffer | |
423 | * @bufb : buffer backend | |
424 | * @offset : offset within the buffer. | |
425 | * | |
426 | * Return the address where a given offset is located. | |
427 | * Should be used to get the current subbuffer header pointer. Given we know | |
428 | * it's always at the beginning of a page, it's safe to write directly to this | |
429 | * address, as long as the write is never bigger than a page size. | |
430 | */ | |
431 | void *lib_ring_buffer_offset_address(struct lib_ring_buffer_backend *bufb, | |
432 | size_t offset) | |
433 | { | |
a6352fd4 | 434 | size_t sbidx; |
852c2936 | 435 | struct lib_ring_buffer_backend_pages *rpages; |
a6352fd4 | 436 | struct channel_backend *chanb = &shmp(bufb->chan)->backend; |
852c2936 MD |
437 | const struct lib_ring_buffer_config *config = chanb->config; |
438 | unsigned long sb_bindex, id; | |
439 | ||
440 | offset &= chanb->buf_size - 1; | |
441 | sbidx = offset >> chanb->subbuf_size_order; | |
a6352fd4 | 442 | id = shmp(bufb->buf_wsb)[sbidx].id; |
852c2936 | 443 | sb_bindex = subbuffer_id_get_index(config, id); |
a6352fd4 | 444 | rpages = shmp(bufb->array)[sb_bindex]; |
852c2936 MD |
445 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE |
446 | && subbuffer_id_is_noref(config, id)); | |
a6352fd4 | 447 | return shmp(rpages->p) + (offset & ~(chanb->subbuf_size - 1)); |
852c2936 | 448 | } |