Commit | Line | Data |
---|---|---|
852c2936 MD |
1 | /* |
2 | * ring_buffer_backend.c | |
3 | * | |
e92f3e28 | 4 | * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
852c2936 | 5 | * |
e92f3e28 MD |
6 | * This library is free software; you can redistribute it and/or |
7 | * modify it under the terms of the GNU Lesser General Public | |
8 | * License as published by the Free Software Foundation; only | |
9 | * version 2.1 of the License. | |
10 | * | |
11 | * This library is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | * Lesser General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU Lesser General Public | |
17 | * License along with this library; if not, write to the Free Software | |
18 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
852c2936 MD |
19 | */ |
20 | ||
3fbec7dc | 21 | #define _LGPL_SOURCE |
b4051ad8 | 22 | #include <stddef.h> |
fb31eb73 | 23 | #include <stdint.h> |
2657d1ba | 24 | #include <unistd.h> |
14641deb | 25 | #include <urcu/arch.h> |
96e80018 | 26 | #include <limits.h> |
14641deb | 27 | |
4318ae1b | 28 | #include <lttng/ringbuffer-config.h> |
2fed87ae | 29 | #include "vatomic.h" |
4931a13e MD |
30 | #include "backend.h" |
31 | #include "frontend.h" | |
a6352fd4 | 32 | #include "smp.h" |
431d5cf0 | 33 | #include "shm.h" |
852c2936 MD |
34 | |
35 | /** | |
36 | * lib_ring_buffer_backend_allocate - allocate a channel buffer | |
37 | * @config: ring buffer instance configuration | |
38 | * @buf: the buffer struct | |
39 | * @size: total size of the buffer | |
40 | * @num_subbuf: number of subbuffers | |
41 | * @extra_reader_sb: need extra subbuffer for reader | |
42 | */ | |
43 | static | |
4cfec15c MD |
44 | int lib_ring_buffer_backend_allocate(const struct lttng_ust_lib_ring_buffer_config *config, |
45 | struct lttng_ust_lib_ring_buffer_backend *bufb, | |
852c2936 | 46 | size_t size, size_t num_subbuf, |
a6352fd4 | 47 | int extra_reader_sb, |
38fae1d3 | 48 | struct lttng_ust_shm_handle *handle, |
1d498196 | 49 | struct shm_object *shmobj) |
852c2936 | 50 | { |
34daae3e | 51 | struct channel_backend *chanb; |
852c2936 MD |
52 | unsigned long subbuf_size, mmap_offset = 0; |
53 | unsigned long num_subbuf_alloc; | |
852c2936 | 54 | unsigned long i; |
2657d1ba | 55 | long page_size; |
852c2936 | 56 | |
34daae3e MD |
57 | chanb = &shmp(handle, bufb->chan)->backend; |
58 | if (!chanb) | |
59 | return -EINVAL; | |
60 | ||
852c2936 MD |
61 | subbuf_size = chanb->subbuf_size; |
62 | num_subbuf_alloc = num_subbuf; | |
63 | ||
a6352fd4 | 64 | if (extra_reader_sb) |
852c2936 | 65 | num_subbuf_alloc++; |
852c2936 | 66 | |
2657d1ba MD |
67 | page_size = sysconf(_SC_PAGE_SIZE); |
68 | if (page_size <= 0) { | |
69 | goto page_size_error; | |
70 | } | |
71 | ||
4cfec15c | 72 | align_shm(shmobj, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages_shmp)); |
1d498196 | 73 | set_shmp(bufb->array, zalloc_shm(shmobj, |
4cfec15c | 74 | sizeof(struct lttng_ust_lib_ring_buffer_backend_pages_shmp) * num_subbuf_alloc)); |
b5a3dfa5 | 75 | if (caa_unlikely(!shmp(handle, bufb->array))) |
852c2936 MD |
76 | goto array_error; |
77 | ||
431d5cf0 MD |
78 | /* |
79 | * This is the largest element (the buffer pages) which needs to | |
2657d1ba | 80 | * be aligned on page size. |
431d5cf0 | 81 | */ |
2657d1ba | 82 | align_shm(shmobj, page_size); |
1d498196 | 83 | set_shmp(bufb->memory_map, zalloc_shm(shmobj, |
a6352fd4 | 84 | subbuf_size * num_subbuf_alloc)); |
b5a3dfa5 | 85 | if (caa_unlikely(!shmp(handle, bufb->memory_map))) |
a6352fd4 | 86 | goto memory_map_error; |
852c2936 MD |
87 | |
88 | /* Allocate backend pages array elements */ | |
89 | for (i = 0; i < num_subbuf_alloc; i++) { | |
4cfec15c | 90 | align_shm(shmobj, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages)); |
aead2025 | 91 | set_shmp(shmp_index(handle, bufb->array, i)->shmp, |
1d498196 | 92 | zalloc_shm(shmobj, |
4cfec15c | 93 | sizeof(struct lttng_ust_lib_ring_buffer_backend_pages))); |
4746ae29 | 94 | if (!shmp(handle, shmp_index(handle, bufb->array, i)->shmp)) |
852c2936 MD |
95 | goto free_array; |
96 | } | |
97 | ||
98 | /* Allocate write-side subbuffer table */ | |
4cfec15c | 99 | align_shm(shmobj, __alignof__(struct lttng_ust_lib_ring_buffer_backend_subbuffer)); |
1d498196 | 100 | set_shmp(bufb->buf_wsb, zalloc_shm(shmobj, |
4cfec15c | 101 | sizeof(struct lttng_ust_lib_ring_buffer_backend_subbuffer) |
1d498196 | 102 | * num_subbuf)); |
b5a3dfa5 | 103 | if (caa_unlikely(!shmp(handle, bufb->buf_wsb))) |
852c2936 MD |
104 | goto free_array; |
105 | ||
34daae3e MD |
106 | for (i = 0; i < num_subbuf; i++) { |
107 | struct lttng_ust_lib_ring_buffer_backend_subbuffer *sb; | |
108 | ||
109 | sb = shmp_index(handle, bufb->buf_wsb, i); | |
110 | if (!sb) | |
111 | goto free_array; | |
112 | sb->id = subbuffer_id(config, 0, 1, i); | |
113 | } | |
852c2936 MD |
114 | |
115 | /* Assign read-side subbuffer table */ | |
116 | if (extra_reader_sb) | |
117 | bufb->buf_rsb.id = subbuffer_id(config, 0, 1, | |
118 | num_subbuf_alloc - 1); | |
119 | else | |
120 | bufb->buf_rsb.id = subbuffer_id(config, 0, 1, 0); | |
121 | ||
1ff31389 | 122 | /* Allocate subbuffer packet counter table */ |
bf8f2ef2 | 123 | align_shm(shmobj, __alignof__(struct lttng_ust_lib_ring_buffer_backend_counts)); |
1ff31389 JD |
124 | set_shmp(bufb->buf_cnt, zalloc_shm(shmobj, |
125 | sizeof(struct lttng_ust_lib_ring_buffer_backend_counts) | |
126 | * num_subbuf)); | |
127 | if (caa_unlikely(!shmp(handle, bufb->buf_cnt))) | |
128 | goto free_wsb; | |
129 | ||
852c2936 MD |
130 | /* Assign pages to page index */ |
131 | for (i = 0; i < num_subbuf_alloc; i++) { | |
34daae3e MD |
132 | struct lttng_ust_lib_ring_buffer_backend_pages_shmp *sbp; |
133 | struct lttng_ust_lib_ring_buffer_backend_pages *pages; | |
1d498196 MD |
134 | struct shm_ref ref; |
135 | ||
136 | ref.index = bufb->memory_map._ref.index; | |
137 | ref.offset = bufb->memory_map._ref.offset; | |
138 | ref.offset += i * subbuf_size; | |
139 | ||
34daae3e MD |
140 | sbp = shmp_index(handle, bufb->array, i); |
141 | if (!sbp) | |
142 | goto free_array; | |
143 | pages = shmp(handle, sbp->shmp); | |
144 | if (!pages) | |
145 | goto free_array; | |
146 | set_shmp(pages->p, ref); | |
852c2936 | 147 | if (config->output == RING_BUFFER_MMAP) { |
34daae3e | 148 | pages->mmap_offset = mmap_offset; |
852c2936 MD |
149 | mmap_offset += subbuf_size; |
150 | } | |
151 | } | |
852c2936 MD |
152 | return 0; |
153 | ||
1ff31389 JD |
154 | free_wsb: |
155 | /* bufb->buf_wsb will be freed by shm teardown */ | |
852c2936 | 156 | free_array: |
a6352fd4 MD |
157 | /* bufb->array[i] will be freed by shm teardown */ |
158 | memory_map_error: | |
159 | /* bufb->array will be freed by shm teardown */ | |
852c2936 | 160 | array_error: |
2657d1ba | 161 | page_size_error: |
852c2936 MD |
162 | return -ENOMEM; |
163 | } | |
164 | ||
4cfec15c | 165 | int lib_ring_buffer_backend_create(struct lttng_ust_lib_ring_buffer_backend *bufb, |
a6352fd4 | 166 | struct channel_backend *chanb, int cpu, |
38fae1d3 | 167 | struct lttng_ust_shm_handle *handle, |
1d498196 | 168 | struct shm_object *shmobj) |
852c2936 | 169 | { |
4cfec15c | 170 | const struct lttng_ust_lib_ring_buffer_config *config = &chanb->config; |
852c2936 | 171 | |
1d498196 | 172 | set_shmp(bufb->chan, handle->chan._ref); |
852c2936 MD |
173 | bufb->cpu = cpu; |
174 | ||
175 | return lib_ring_buffer_backend_allocate(config, bufb, chanb->buf_size, | |
176 | chanb->num_subbuf, | |
a6352fd4 | 177 | chanb->extra_reader_sb, |
1d498196 | 178 | handle, shmobj); |
852c2936 MD |
179 | } |
180 | ||
4cfec15c | 181 | void lib_ring_buffer_backend_reset(struct lttng_ust_lib_ring_buffer_backend *bufb, |
38fae1d3 | 182 | struct lttng_ust_shm_handle *handle) |
852c2936 | 183 | { |
34daae3e MD |
184 | struct channel_backend *chanb; |
185 | const struct lttng_ust_lib_ring_buffer_config *config; | |
852c2936 MD |
186 | unsigned long num_subbuf_alloc; |
187 | unsigned int i; | |
188 | ||
34daae3e MD |
189 | chanb = &shmp(handle, bufb->chan)->backend; |
190 | if (!chanb) | |
15500a1b | 191 | return; |
34daae3e MD |
192 | config = &chanb->config; |
193 | ||
852c2936 MD |
194 | num_subbuf_alloc = chanb->num_subbuf; |
195 | if (chanb->extra_reader_sb) | |
196 | num_subbuf_alloc++; | |
197 | ||
34daae3e MD |
198 | for (i = 0; i < chanb->num_subbuf; i++) { |
199 | struct lttng_ust_lib_ring_buffer_backend_subbuffer *sb; | |
200 | ||
201 | sb = shmp_index(handle, bufb->buf_wsb, i); | |
202 | if (!sb) | |
15500a1b | 203 | return; |
34daae3e MD |
204 | sb->id = subbuffer_id(config, 0, 1, i); |
205 | } | |
852c2936 MD |
206 | if (chanb->extra_reader_sb) |
207 | bufb->buf_rsb.id = subbuffer_id(config, 0, 1, | |
208 | num_subbuf_alloc - 1); | |
209 | else | |
210 | bufb->buf_rsb.id = subbuffer_id(config, 0, 1, 0); | |
211 | ||
212 | for (i = 0; i < num_subbuf_alloc; i++) { | |
34daae3e MD |
213 | struct lttng_ust_lib_ring_buffer_backend_pages_shmp *sbp; |
214 | struct lttng_ust_lib_ring_buffer_backend_pages *pages; | |
215 | ||
216 | sbp = shmp_index(handle, bufb->array, i); | |
217 | if (!sbp) | |
15500a1b | 218 | return; |
34daae3e MD |
219 | pages = shmp(handle, sbp->shmp); |
220 | if (!pages) | |
15500a1b | 221 | return; |
852c2936 | 222 | /* Don't reset mmap_offset */ |
34daae3e MD |
223 | v_set(config, &pages->records_commit, 0); |
224 | v_set(config, &pages->records_unread, 0); | |
225 | pages->data_size = 0; | |
852c2936 MD |
226 | /* Don't reset backend page and virt addresses */ |
227 | } | |
228 | /* Don't reset num_pages_per_subbuf, cpu, allocated */ | |
229 | v_set(config, &bufb->records_read, 0); | |
230 | } | |
231 | ||
232 | /* | |
233 | * The frontend is responsible for also calling ring_buffer_backend_reset for | |
234 | * each buffer when calling channel_backend_reset. | |
235 | */ | |
236 | void channel_backend_reset(struct channel_backend *chanb) | |
237 | { | |
14641deb | 238 | struct channel *chan = caa_container_of(chanb, struct channel, backend); |
4cfec15c | 239 | const struct lttng_ust_lib_ring_buffer_config *config = &chanb->config; |
852c2936 MD |
240 | |
241 | /* | |
242 | * Don't reset buf_size, subbuf_size, subbuf_size_order, | |
243 | * num_subbuf_order, buf_size_order, extra_reader_sb, num_subbuf, | |
244 | * priv, notifiers, config, cpumask and name. | |
245 | */ | |
246 | chanb->start_tsc = config->cb.ring_buffer_clock_read(chan); | |
247 | } | |
248 | ||
852c2936 MD |
249 | /** |
250 | * channel_backend_init - initialize a channel backend | |
251 | * @chanb: channel backend | |
252 | * @name: channel name | |
253 | * @config: client ring buffer configuration | |
852c2936 | 254 | * @parent: dentry of parent directory, %NULL for root directory |
2657d1ba | 255 | * @subbuf_size: size of sub-buffers (> page size, power of 2) |
852c2936 | 256 | * @num_subbuf: number of sub-buffers (power of 2) |
38fae1d3 | 257 | * @lttng_ust_shm_handle: shared memory handle |
5ea386c3 | 258 | * @stream_fds: stream file descriptors. |
852c2936 MD |
259 | * |
260 | * Returns channel pointer if successful, %NULL otherwise. | |
261 | * | |
262 | * Creates per-cpu channel buffers using the sizes and attributes | |
263 | * specified. The created channel buffer files will be named | |
264 | * name_0...name_N-1. File permissions will be %S_IRUSR. | |
265 | * | |
266 | * Called with CPU hotplug disabled. | |
267 | */ | |
268 | int channel_backend_init(struct channel_backend *chanb, | |
269 | const char *name, | |
4cfec15c | 270 | const struct lttng_ust_lib_ring_buffer_config *config, |
a3f61e7f | 271 | size_t subbuf_size, size_t num_subbuf, |
a9ff648c | 272 | struct lttng_ust_shm_handle *handle, |
5ea386c3 | 273 | const int *stream_fds) |
852c2936 | 274 | { |
14641deb | 275 | struct channel *chan = caa_container_of(chanb, struct channel, backend); |
852c2936 MD |
276 | unsigned int i; |
277 | int ret; | |
6c1f7d8b | 278 | size_t shmsize = 0, num_subbuf_alloc; |
2657d1ba | 279 | long page_size; |
852c2936 MD |
280 | |
281 | if (!name) | |
282 | return -EPERM; | |
283 | ||
2657d1ba MD |
284 | page_size = sysconf(_SC_PAGE_SIZE); |
285 | if (page_size <= 0) { | |
286 | return -ENOMEM; | |
287 | } | |
852c2936 | 288 | /* Check that the subbuffer size is larger than a page. */ |
2657d1ba | 289 | if (subbuf_size < page_size) |
852c2936 MD |
290 | return -EINVAL; |
291 | ||
292 | /* | |
12bcbbdb MD |
293 | * Make sure the number of subbuffers and subbuffer size are |
294 | * power of 2, and nonzero. | |
852c2936 | 295 | */ |
12bcbbdb | 296 | if (!subbuf_size || (subbuf_size & (subbuf_size - 1))) |
e52b0723 | 297 | return -EINVAL; |
12bcbbdb | 298 | if (!num_subbuf || (num_subbuf & (num_subbuf - 1))) |
e52b0723 | 299 | return -EINVAL; |
3d8e9399 MD |
300 | /* |
301 | * Overwrite mode buffers require at least 2 subbuffers per | |
302 | * buffer. | |
303 | */ | |
304 | if (config->mode == RING_BUFFER_OVERWRITE && num_subbuf < 2) | |
305 | return -EINVAL; | |
852c2936 MD |
306 | |
307 | ret = subbuffer_id_check_index(config, num_subbuf); | |
308 | if (ret) | |
309 | return ret; | |
310 | ||
852c2936 MD |
311 | chanb->buf_size = num_subbuf * subbuf_size; |
312 | chanb->subbuf_size = subbuf_size; | |
313 | chanb->buf_size_order = get_count_order(chanb->buf_size); | |
314 | chanb->subbuf_size_order = get_count_order(subbuf_size); | |
315 | chanb->num_subbuf_order = get_count_order(num_subbuf); | |
316 | chanb->extra_reader_sb = | |
317 | (config->mode == RING_BUFFER_OVERWRITE) ? 1 : 0; | |
318 | chanb->num_subbuf = num_subbuf; | |
a6352fd4 MD |
319 | strncpy(chanb->name, name, NAME_MAX); |
320 | chanb->name[NAME_MAX - 1] = '\0'; | |
193183fb | 321 | memcpy(&chanb->config, config, sizeof(*config)); |
852c2936 | 322 | |
1d498196 | 323 | /* Per-cpu buffer size: control (prior to backend) */ |
4cfec15c MD |
324 | shmsize = offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer)); |
325 | shmsize += sizeof(struct lttng_ust_lib_ring_buffer); | |
d2f09c1c MD |
326 | shmsize += offset_align(shmsize, __alignof__(struct commit_counters_hot)); |
327 | shmsize += sizeof(struct commit_counters_hot) * num_subbuf; | |
328 | shmsize += offset_align(shmsize, __alignof__(struct commit_counters_cold)); | |
329 | shmsize += sizeof(struct commit_counters_cold) * num_subbuf; | |
330 | /* Sampled timestamp end */ | |
331 | shmsize += offset_align(shmsize, __alignof__(uint64_t)); | |
332 | shmsize += sizeof(uint64_t) * num_subbuf; | |
1d498196 MD |
333 | |
334 | /* Per-cpu buffer size: backend */ | |
335 | /* num_subbuf + 1 is the worse case */ | |
336 | num_subbuf_alloc = num_subbuf + 1; | |
4cfec15c MD |
337 | shmsize += offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages_shmp)); |
338 | shmsize += sizeof(struct lttng_ust_lib_ring_buffer_backend_pages_shmp) * num_subbuf_alloc; | |
2657d1ba | 339 | shmsize += offset_align(shmsize, page_size); |
1d498196 | 340 | shmsize += subbuf_size * num_subbuf_alloc; |
4cfec15c MD |
341 | shmsize += offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages)); |
342 | shmsize += sizeof(struct lttng_ust_lib_ring_buffer_backend_pages) * num_subbuf_alloc; | |
343 | shmsize += offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer_backend_subbuffer)); | |
344 | shmsize += sizeof(struct lttng_ust_lib_ring_buffer_backend_subbuffer) * num_subbuf; | |
bf8f2ef2 LL |
345 | shmsize += offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer_backend_counts)); |
346 | shmsize += sizeof(struct lttng_ust_lib_ring_buffer_backend_counts) * num_subbuf; | |
1d498196 | 347 | |
852c2936 | 348 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) { |
4cfec15c | 349 | struct lttng_ust_lib_ring_buffer *buf; |
852c2936 | 350 | /* |
a6352fd4 | 351 | * We need to allocate for all possible cpus. |
852c2936 | 352 | */ |
852c2936 | 353 | for_each_possible_cpu(i) { |
1d498196 | 354 | struct shm_object *shmobj; |
5ea386c3 | 355 | |
74d81a6c | 356 | shmobj = shm_object_table_alloc(handle->table, shmsize, |
4b68c31f | 357 | SHM_OBJECT_SHM, stream_fds[i], i); |
afdf9825 MD |
358 | if (!shmobj) |
359 | goto end; | |
4cfec15c MD |
360 | align_shm(shmobj, __alignof__(struct lttng_ust_lib_ring_buffer)); |
361 | set_shmp(chanb->buf[i].shmp, zalloc_shm(shmobj, sizeof(struct lttng_ust_lib_ring_buffer))); | |
1d498196 MD |
362 | buf = shmp(handle, chanb->buf[i].shmp); |
363 | if (!buf) | |
364 | goto end; | |
5d61a504 | 365 | set_shmp(buf->self, chanb->buf[i].shmp._ref); |
1d498196 MD |
366 | ret = lib_ring_buffer_create(buf, chanb, i, |
367 | handle, shmobj); | |
852c2936 MD |
368 | if (ret) |
369 | goto free_bufs; /* cpu hotplug locked */ | |
370 | } | |
852c2936 | 371 | } else { |
1d498196 | 372 | struct shm_object *shmobj; |
4cfec15c | 373 | struct lttng_ust_lib_ring_buffer *buf; |
a6352fd4 | 374 | |
74d81a6c | 375 | shmobj = shm_object_table_alloc(handle->table, shmsize, |
4b68c31f | 376 | SHM_OBJECT_SHM, stream_fds[0], -1); |
afdf9825 MD |
377 | if (!shmobj) |
378 | goto end; | |
4cfec15c MD |
379 | align_shm(shmobj, __alignof__(struct lttng_ust_lib_ring_buffer)); |
380 | set_shmp(chanb->buf[0].shmp, zalloc_shm(shmobj, sizeof(struct lttng_ust_lib_ring_buffer))); | |
1d498196 | 381 | buf = shmp(handle, chanb->buf[0].shmp); |
a6352fd4 MD |
382 | if (!buf) |
383 | goto end; | |
cb14bae9 | 384 | set_shmp(buf->self, chanb->buf[0].shmp._ref); |
1d498196 MD |
385 | ret = lib_ring_buffer_create(buf, chanb, -1, |
386 | handle, shmobj); | |
852c2936 MD |
387 | if (ret) |
388 | goto free_bufs; | |
389 | } | |
390 | chanb->start_tsc = config->cb.ring_buffer_clock_read(chan); | |
391 | ||
392 | return 0; | |
393 | ||
394 | free_bufs: | |
a6352fd4 MD |
395 | /* We only free the buffer data upon shm teardown */ |
396 | end: | |
852c2936 MD |
397 | return -ENOMEM; |
398 | } | |
399 | ||
852c2936 MD |
400 | /** |
401 | * channel_backend_free - destroy the channel | |
402 | * @chan: the channel | |
403 | * | |
404 | * Destroy all channel buffers and frees the channel. | |
405 | */ | |
1d498196 | 406 | void channel_backend_free(struct channel_backend *chanb, |
38fae1d3 | 407 | struct lttng_ust_shm_handle *handle) |
852c2936 | 408 | { |
45e9e699 | 409 | /* SHM teardown takes care of everything */ |
852c2936 MD |
410 | } |
411 | ||
852c2936 MD |
412 | /** |
413 | * lib_ring_buffer_read - read data from ring_buffer_buffer. | |
414 | * @bufb : buffer backend | |
415 | * @offset : offset within the buffer | |
416 | * @dest : destination address | |
417 | * @len : length to copy to destination | |
418 | * | |
419 | * Should be protected by get_subbuf/put_subbuf. | |
420 | * Returns the length copied. | |
421 | */ | |
4cfec15c | 422 | size_t lib_ring_buffer_read(struct lttng_ust_lib_ring_buffer_backend *bufb, size_t offset, |
38fae1d3 | 423 | void *dest, size_t len, struct lttng_ust_shm_handle *handle) |
852c2936 | 424 | { |
34daae3e MD |
425 | struct channel_backend *chanb; |
426 | const struct lttng_ust_lib_ring_buffer_config *config; | |
a6352fd4 | 427 | ssize_t orig_len; |
4cfec15c | 428 | struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages; |
15500a1b | 429 | struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages; |
852c2936 | 430 | unsigned long sb_bindex, id; |
99b99b47 | 431 | void *src; |
852c2936 | 432 | |
34daae3e MD |
433 | chanb = &shmp(handle, bufb->chan)->backend; |
434 | if (!chanb) | |
435 | return 0; | |
436 | config = &chanb->config; | |
852c2936 MD |
437 | orig_len = len; |
438 | offset &= chanb->buf_size - 1; | |
a6352fd4 | 439 | |
b5a3dfa5 | 440 | if (caa_unlikely(!len)) |
852c2936 | 441 | return 0; |
a6352fd4 MD |
442 | id = bufb->buf_rsb.id; |
443 | sb_bindex = subbuffer_id_get_index(config, id); | |
4746ae29 | 444 | rpages = shmp_index(handle, bufb->array, sb_bindex); |
15500a1b MD |
445 | if (!rpages) |
446 | return 0; | |
a6352fd4 MD |
447 | /* |
448 | * Underlying layer should never ask for reads across | |
449 | * subbuffers. | |
450 | */ | |
451 | CHAN_WARN_ON(chanb, offset >= chanb->buf_size); | |
452 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE | |
453 | && subbuffer_id_is_noref(config, id)); | |
15500a1b MD |
454 | backend_pages = shmp(handle, rpages->shmp); |
455 | if (!backend_pages) | |
456 | return 0; | |
457 | src = shmp_index(handle, backend_pages->p, offset & (chanb->subbuf_size - 1)); | |
99b99b47 MD |
458 | if (caa_unlikely(!src)) |
459 | return 0; | |
460 | memcpy(dest, src, len); | |
852c2936 MD |
461 | return orig_len; |
462 | } | |
852c2936 | 463 | |
852c2936 MD |
464 | /** |
465 | * lib_ring_buffer_read_cstr - read a C-style string from ring_buffer. | |
466 | * @bufb : buffer backend | |
467 | * @offset : offset within the buffer | |
468 | * @dest : destination address | |
469 | * @len : destination's length | |
470 | * | |
0bf3c920 | 471 | * Return string's length, or -EINVAL on error. |
852c2936 | 472 | * Should be protected by get_subbuf/put_subbuf. |
0bf3c920 | 473 | * Destination length should be at least 1 to hold '\0'. |
852c2936 | 474 | */ |
4cfec15c | 475 | int lib_ring_buffer_read_cstr(struct lttng_ust_lib_ring_buffer_backend *bufb, size_t offset, |
38fae1d3 | 476 | void *dest, size_t len, struct lttng_ust_shm_handle *handle) |
852c2936 | 477 | { |
34daae3e MD |
478 | struct channel_backend *chanb; |
479 | const struct lttng_ust_lib_ring_buffer_config *config; | |
a6352fd4 | 480 | ssize_t string_len, orig_offset; |
852c2936 | 481 | char *str; |
4cfec15c | 482 | struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages; |
15500a1b | 483 | struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages; |
852c2936 MD |
484 | unsigned long sb_bindex, id; |
485 | ||
34daae3e MD |
486 | chanb = &shmp(handle, bufb->chan)->backend; |
487 | if (!chanb) | |
488 | return -EINVAL; | |
489 | config = &chanb->config; | |
0bf3c920 MD |
490 | if (caa_unlikely(!len)) |
491 | return -EINVAL; | |
852c2936 | 492 | offset &= chanb->buf_size - 1; |
852c2936 | 493 | orig_offset = offset; |
852c2936 MD |
494 | id = bufb->buf_rsb.id; |
495 | sb_bindex = subbuffer_id_get_index(config, id); | |
4746ae29 | 496 | rpages = shmp_index(handle, bufb->array, sb_bindex); |
15500a1b MD |
497 | if (!rpages) |
498 | return -EINVAL; | |
a6352fd4 MD |
499 | /* |
500 | * Underlying layer should never ask for reads across | |
501 | * subbuffers. | |
502 | */ | |
503 | CHAN_WARN_ON(chanb, offset >= chanb->buf_size); | |
852c2936 MD |
504 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE |
505 | && subbuffer_id_is_noref(config, id)); | |
15500a1b MD |
506 | backend_pages = shmp(handle, rpages->shmp); |
507 | if (!backend_pages) | |
508 | return -EINVAL; | |
509 | str = shmp_index(handle, backend_pages->p, offset & (chanb->subbuf_size - 1)); | |
99b99b47 MD |
510 | if (caa_unlikely(!str)) |
511 | return -EINVAL; | |
a6352fd4 MD |
512 | string_len = strnlen(str, len); |
513 | if (dest && len) { | |
514 | memcpy(dest, str, string_len); | |
515 | ((char *)dest)[0] = 0; | |
516 | } | |
517 | return offset - orig_offset; | |
852c2936 | 518 | } |
852c2936 MD |
519 | |
520 | /** | |
521 | * lib_ring_buffer_read_offset_address - get address of a buffer location | |
522 | * @bufb : buffer backend | |
523 | * @offset : offset within the buffer. | |
524 | * | |
525 | * Return the address where a given offset is located (for read). | |
526 | * Should be used to get the current subbuffer header pointer. Given we know | |
22b22ce9 MD |
527 | * it's never on a page boundary, it's safe to read/write directly |
528 | * from/to this address, as long as the read/write is never bigger than | |
529 | * a page size. | |
852c2936 | 530 | */ |
4cfec15c | 531 | void *lib_ring_buffer_read_offset_address(struct lttng_ust_lib_ring_buffer_backend *bufb, |
1d498196 | 532 | size_t offset, |
38fae1d3 | 533 | struct lttng_ust_shm_handle *handle) |
852c2936 | 534 | { |
4cfec15c | 535 | struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages; |
15500a1b | 536 | struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages; |
34daae3e MD |
537 | struct channel_backend *chanb; |
538 | const struct lttng_ust_lib_ring_buffer_config *config; | |
852c2936 MD |
539 | unsigned long sb_bindex, id; |
540 | ||
34daae3e MD |
541 | chanb = &shmp(handle, bufb->chan)->backend; |
542 | if (!chanb) | |
543 | return NULL; | |
544 | config = &chanb->config; | |
852c2936 | 545 | offset &= chanb->buf_size - 1; |
852c2936 MD |
546 | id = bufb->buf_rsb.id; |
547 | sb_bindex = subbuffer_id_get_index(config, id); | |
4746ae29 | 548 | rpages = shmp_index(handle, bufb->array, sb_bindex); |
15500a1b MD |
549 | if (!rpages) |
550 | return NULL; | |
852c2936 MD |
551 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE |
552 | && subbuffer_id_is_noref(config, id)); | |
15500a1b MD |
553 | backend_pages = shmp(handle, rpages->shmp); |
554 | if (!backend_pages) | |
555 | return NULL; | |
556 | return shmp_index(handle, backend_pages->p, offset & (chanb->subbuf_size - 1)); | |
852c2936 | 557 | } |
852c2936 MD |
558 | |
559 | /** | |
560 | * lib_ring_buffer_offset_address - get address of a location within the buffer | |
561 | * @bufb : buffer backend | |
562 | * @offset : offset within the buffer. | |
563 | * | |
564 | * Return the address where a given offset is located. | |
565 | * Should be used to get the current subbuffer header pointer. Given we know | |
566 | * it's always at the beginning of a page, it's safe to write directly to this | |
567 | * address, as long as the write is never bigger than a page size. | |
568 | */ | |
4cfec15c | 569 | void *lib_ring_buffer_offset_address(struct lttng_ust_lib_ring_buffer_backend *bufb, |
1d498196 | 570 | size_t offset, |
38fae1d3 | 571 | struct lttng_ust_shm_handle *handle) |
852c2936 | 572 | { |
a6352fd4 | 573 | size_t sbidx; |
4cfec15c | 574 | struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages; |
15500a1b | 575 | struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages; |
34daae3e MD |
576 | struct channel_backend *chanb; |
577 | const struct lttng_ust_lib_ring_buffer_config *config; | |
852c2936 | 578 | unsigned long sb_bindex, id; |
34daae3e | 579 | struct lttng_ust_lib_ring_buffer_backend_subbuffer *sb; |
852c2936 | 580 | |
34daae3e MD |
581 | chanb = &shmp(handle, bufb->chan)->backend; |
582 | if (!chanb) | |
583 | return NULL; | |
584 | config = &chanb->config; | |
852c2936 MD |
585 | offset &= chanb->buf_size - 1; |
586 | sbidx = offset >> chanb->subbuf_size_order; | |
34daae3e MD |
587 | sb = shmp_index(handle, bufb->buf_wsb, sbidx); |
588 | if (!sb) | |
589 | return NULL; | |
590 | id = sb->id; | |
852c2936 | 591 | sb_bindex = subbuffer_id_get_index(config, id); |
4746ae29 | 592 | rpages = shmp_index(handle, bufb->array, sb_bindex); |
15500a1b MD |
593 | if (!rpages) |
594 | return NULL; | |
852c2936 MD |
595 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE |
596 | && subbuffer_id_is_noref(config, id)); | |
15500a1b MD |
597 | backend_pages = shmp(handle, rpages->shmp); |
598 | if (!backend_pages) | |
599 | return NULL; | |
600 | return shmp_index(handle, backend_pages->p, offset & (chanb->subbuf_size - 1)); | |
852c2936 | 601 | } |