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 | ||
5ad63a16 | 21 | #define _GNU_SOURCE |
14641deb | 22 | #include <urcu/arch.h> |
96e80018 | 23 | #include <limits.h> |
14641deb | 24 | |
4318ae1b | 25 | #include <lttng/ringbuffer-config.h> |
2fed87ae | 26 | #include "vatomic.h" |
4931a13e MD |
27 | #include "backend.h" |
28 | #include "frontend.h" | |
a6352fd4 | 29 | #include "smp.h" |
431d5cf0 | 30 | #include "shm.h" |
852c2936 MD |
31 | |
32 | /** | |
33 | * lib_ring_buffer_backend_allocate - allocate a channel buffer | |
34 | * @config: ring buffer instance configuration | |
35 | * @buf: the buffer struct | |
36 | * @size: total size of the buffer | |
37 | * @num_subbuf: number of subbuffers | |
38 | * @extra_reader_sb: need extra subbuffer for reader | |
39 | */ | |
40 | static | |
4cfec15c MD |
41 | int lib_ring_buffer_backend_allocate(const struct lttng_ust_lib_ring_buffer_config *config, |
42 | struct lttng_ust_lib_ring_buffer_backend *bufb, | |
852c2936 | 43 | size_t size, size_t num_subbuf, |
a6352fd4 | 44 | int extra_reader_sb, |
38fae1d3 | 45 | struct lttng_ust_shm_handle *handle, |
1d498196 | 46 | struct shm_object *shmobj) |
852c2936 | 47 | { |
1d498196 | 48 | struct channel_backend *chanb = &shmp(handle, bufb->chan)->backend; |
852c2936 MD |
49 | unsigned long subbuf_size, mmap_offset = 0; |
50 | unsigned long num_subbuf_alloc; | |
852c2936 MD |
51 | unsigned long i; |
52 | ||
852c2936 MD |
53 | subbuf_size = chanb->subbuf_size; |
54 | num_subbuf_alloc = num_subbuf; | |
55 | ||
a6352fd4 | 56 | if (extra_reader_sb) |
852c2936 | 57 | num_subbuf_alloc++; |
852c2936 | 58 | |
4cfec15c | 59 | align_shm(shmobj, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages_shmp)); |
1d498196 | 60 | set_shmp(bufb->array, zalloc_shm(shmobj, |
4cfec15c | 61 | sizeof(struct lttng_ust_lib_ring_buffer_backend_pages_shmp) * num_subbuf_alloc)); |
b5a3dfa5 | 62 | if (caa_unlikely(!shmp(handle, bufb->array))) |
852c2936 MD |
63 | goto array_error; |
64 | ||
431d5cf0 MD |
65 | /* |
66 | * This is the largest element (the buffer pages) which needs to | |
67 | * be aligned on PAGE_SIZE. | |
68 | */ | |
1d498196 MD |
69 | align_shm(shmobj, PAGE_SIZE); |
70 | set_shmp(bufb->memory_map, zalloc_shm(shmobj, | |
a6352fd4 | 71 | subbuf_size * num_subbuf_alloc)); |
b5a3dfa5 | 72 | if (caa_unlikely(!shmp(handle, bufb->memory_map))) |
a6352fd4 | 73 | goto memory_map_error; |
852c2936 MD |
74 | |
75 | /* Allocate backend pages array elements */ | |
76 | for (i = 0; i < num_subbuf_alloc; i++) { | |
4cfec15c | 77 | align_shm(shmobj, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages)); |
aead2025 | 78 | set_shmp(shmp_index(handle, bufb->array, i)->shmp, |
1d498196 | 79 | zalloc_shm(shmobj, |
4cfec15c | 80 | sizeof(struct lttng_ust_lib_ring_buffer_backend_pages))); |
4746ae29 | 81 | if (!shmp(handle, shmp_index(handle, bufb->array, i)->shmp)) |
852c2936 MD |
82 | goto free_array; |
83 | } | |
84 | ||
85 | /* Allocate write-side subbuffer table */ | |
4cfec15c | 86 | align_shm(shmobj, __alignof__(struct lttng_ust_lib_ring_buffer_backend_subbuffer)); |
1d498196 | 87 | set_shmp(bufb->buf_wsb, zalloc_shm(shmobj, |
4cfec15c | 88 | sizeof(struct lttng_ust_lib_ring_buffer_backend_subbuffer) |
1d498196 | 89 | * num_subbuf)); |
b5a3dfa5 | 90 | if (caa_unlikely(!shmp(handle, bufb->buf_wsb))) |
852c2936 MD |
91 | goto free_array; |
92 | ||
93 | for (i = 0; i < num_subbuf; i++) | |
4746ae29 | 94 | shmp_index(handle, bufb->buf_wsb, i)->id = subbuffer_id(config, 0, 1, i); |
852c2936 MD |
95 | |
96 | /* Assign read-side subbuffer table */ | |
97 | if (extra_reader_sb) | |
98 | bufb->buf_rsb.id = subbuffer_id(config, 0, 1, | |
99 | num_subbuf_alloc - 1); | |
100 | else | |
101 | bufb->buf_rsb.id = subbuffer_id(config, 0, 1, 0); | |
102 | ||
103 | /* Assign pages to page index */ | |
104 | for (i = 0; i < num_subbuf_alloc; i++) { | |
1d498196 MD |
105 | struct shm_ref ref; |
106 | ||
107 | ref.index = bufb->memory_map._ref.index; | |
108 | ref.offset = bufb->memory_map._ref.offset; | |
109 | ref.offset += i * subbuf_size; | |
110 | ||
4746ae29 | 111 | set_shmp(shmp(handle, shmp_index(handle, bufb->array, i)->shmp)->p, |
1d498196 | 112 | ref); |
852c2936 | 113 | if (config->output == RING_BUFFER_MMAP) { |
4746ae29 | 114 | shmp(handle, shmp_index(handle, bufb->array, i)->shmp)->mmap_offset = mmap_offset; |
852c2936 MD |
115 | mmap_offset += subbuf_size; |
116 | } | |
117 | } | |
118 | ||
852c2936 MD |
119 | return 0; |
120 | ||
121 | free_array: | |
a6352fd4 MD |
122 | /* bufb->array[i] will be freed by shm teardown */ |
123 | memory_map_error: | |
124 | /* bufb->array will be freed by shm teardown */ | |
852c2936 | 125 | array_error: |
852c2936 MD |
126 | return -ENOMEM; |
127 | } | |
128 | ||
4cfec15c | 129 | int lib_ring_buffer_backend_create(struct lttng_ust_lib_ring_buffer_backend *bufb, |
a6352fd4 | 130 | struct channel_backend *chanb, int cpu, |
38fae1d3 | 131 | struct lttng_ust_shm_handle *handle, |
1d498196 | 132 | struct shm_object *shmobj) |
852c2936 | 133 | { |
4cfec15c | 134 | const struct lttng_ust_lib_ring_buffer_config *config = &chanb->config; |
852c2936 | 135 | |
1d498196 | 136 | set_shmp(bufb->chan, handle->chan._ref); |
852c2936 MD |
137 | bufb->cpu = cpu; |
138 | ||
139 | return lib_ring_buffer_backend_allocate(config, bufb, chanb->buf_size, | |
140 | chanb->num_subbuf, | |
a6352fd4 | 141 | chanb->extra_reader_sb, |
1d498196 | 142 | handle, shmobj); |
852c2936 MD |
143 | } |
144 | ||
4cfec15c | 145 | void lib_ring_buffer_backend_reset(struct lttng_ust_lib_ring_buffer_backend *bufb, |
38fae1d3 | 146 | struct lttng_ust_shm_handle *handle) |
852c2936 | 147 | { |
1d498196 | 148 | struct channel_backend *chanb = &shmp(handle, bufb->chan)->backend; |
4cfec15c | 149 | const struct lttng_ust_lib_ring_buffer_config *config = &chanb->config; |
852c2936 MD |
150 | unsigned long num_subbuf_alloc; |
151 | unsigned int i; | |
152 | ||
153 | num_subbuf_alloc = chanb->num_subbuf; | |
154 | if (chanb->extra_reader_sb) | |
155 | num_subbuf_alloc++; | |
156 | ||
157 | for (i = 0; i < chanb->num_subbuf; i++) | |
4746ae29 | 158 | shmp_index(handle, bufb->buf_wsb, i)->id = subbuffer_id(config, 0, 1, i); |
852c2936 MD |
159 | if (chanb->extra_reader_sb) |
160 | bufb->buf_rsb.id = subbuffer_id(config, 0, 1, | |
161 | num_subbuf_alloc - 1); | |
162 | else | |
163 | bufb->buf_rsb.id = subbuffer_id(config, 0, 1, 0); | |
164 | ||
165 | for (i = 0; i < num_subbuf_alloc; i++) { | |
166 | /* Don't reset mmap_offset */ | |
4746ae29 MD |
167 | v_set(config, &shmp(handle, shmp_index(handle, bufb->array, i)->shmp)->records_commit, 0); |
168 | v_set(config, &shmp(handle, shmp_index(handle, bufb->array, i)->shmp)->records_unread, 0); | |
169 | shmp(handle, shmp_index(handle, bufb->array, i)->shmp)->data_size = 0; | |
852c2936 MD |
170 | /* Don't reset backend page and virt addresses */ |
171 | } | |
172 | /* Don't reset num_pages_per_subbuf, cpu, allocated */ | |
173 | v_set(config, &bufb->records_read, 0); | |
174 | } | |
175 | ||
176 | /* | |
177 | * The frontend is responsible for also calling ring_buffer_backend_reset for | |
178 | * each buffer when calling channel_backend_reset. | |
179 | */ | |
180 | void channel_backend_reset(struct channel_backend *chanb) | |
181 | { | |
14641deb | 182 | struct channel *chan = caa_container_of(chanb, struct channel, backend); |
4cfec15c | 183 | const struct lttng_ust_lib_ring_buffer_config *config = &chanb->config; |
852c2936 MD |
184 | |
185 | /* | |
186 | * Don't reset buf_size, subbuf_size, subbuf_size_order, | |
187 | * num_subbuf_order, buf_size_order, extra_reader_sb, num_subbuf, | |
188 | * priv, notifiers, config, cpumask and name. | |
189 | */ | |
190 | chanb->start_tsc = config->cb.ring_buffer_clock_read(chan); | |
191 | } | |
192 | ||
852c2936 MD |
193 | /** |
194 | * channel_backend_init - initialize a channel backend | |
195 | * @chanb: channel backend | |
196 | * @name: channel name | |
197 | * @config: client ring buffer configuration | |
852c2936 MD |
198 | * @parent: dentry of parent directory, %NULL for root directory |
199 | * @subbuf_size: size of sub-buffers (> PAGE_SIZE, power of 2) | |
200 | * @num_subbuf: number of sub-buffers (power of 2) | |
38fae1d3 | 201 | * @lttng_ust_shm_handle: shared memory handle |
852c2936 MD |
202 | * |
203 | * Returns channel pointer if successful, %NULL otherwise. | |
204 | * | |
205 | * Creates per-cpu channel buffers using the sizes and attributes | |
206 | * specified. The created channel buffer files will be named | |
207 | * name_0...name_N-1. File permissions will be %S_IRUSR. | |
208 | * | |
209 | * Called with CPU hotplug disabled. | |
210 | */ | |
211 | int channel_backend_init(struct channel_backend *chanb, | |
212 | const char *name, | |
4cfec15c | 213 | const struct lttng_ust_lib_ring_buffer_config *config, |
a3f61e7f | 214 | size_t subbuf_size, size_t num_subbuf, |
38fae1d3 | 215 | struct lttng_ust_shm_handle *handle) |
852c2936 | 216 | { |
14641deb | 217 | struct channel *chan = caa_container_of(chanb, struct channel, backend); |
852c2936 MD |
218 | unsigned int i; |
219 | int ret; | |
6c1f7d8b | 220 | size_t shmsize = 0, num_subbuf_alloc; |
852c2936 MD |
221 | |
222 | if (!name) | |
223 | return -EPERM; | |
224 | ||
852c2936 MD |
225 | /* Check that the subbuffer size is larger than a page. */ |
226 | if (subbuf_size < PAGE_SIZE) | |
227 | return -EINVAL; | |
228 | ||
229 | /* | |
12bcbbdb MD |
230 | * Make sure the number of subbuffers and subbuffer size are |
231 | * power of 2, and nonzero. | |
852c2936 | 232 | */ |
12bcbbdb | 233 | if (!subbuf_size || (subbuf_size & (subbuf_size - 1))) |
e52b0723 | 234 | return -EINVAL; |
12bcbbdb | 235 | if (!num_subbuf || (num_subbuf & (num_subbuf - 1))) |
e52b0723 | 236 | return -EINVAL; |
3d8e9399 MD |
237 | /* |
238 | * Overwrite mode buffers require at least 2 subbuffers per | |
239 | * buffer. | |
240 | */ | |
241 | if (config->mode == RING_BUFFER_OVERWRITE && num_subbuf < 2) | |
242 | return -EINVAL; | |
852c2936 MD |
243 | |
244 | ret = subbuffer_id_check_index(config, num_subbuf); | |
245 | if (ret) | |
246 | return ret; | |
247 | ||
852c2936 MD |
248 | chanb->buf_size = num_subbuf * subbuf_size; |
249 | chanb->subbuf_size = subbuf_size; | |
250 | chanb->buf_size_order = get_count_order(chanb->buf_size); | |
251 | chanb->subbuf_size_order = get_count_order(subbuf_size); | |
252 | chanb->num_subbuf_order = get_count_order(num_subbuf); | |
253 | chanb->extra_reader_sb = | |
254 | (config->mode == RING_BUFFER_OVERWRITE) ? 1 : 0; | |
255 | chanb->num_subbuf = num_subbuf; | |
a6352fd4 MD |
256 | strncpy(chanb->name, name, NAME_MAX); |
257 | chanb->name[NAME_MAX - 1] = '\0'; | |
193183fb | 258 | memcpy(&chanb->config, config, sizeof(*config)); |
852c2936 | 259 | |
1d498196 | 260 | /* Per-cpu buffer size: control (prior to backend) */ |
4cfec15c MD |
261 | shmsize = offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer)); |
262 | shmsize += sizeof(struct lttng_ust_lib_ring_buffer); | |
1d498196 MD |
263 | |
264 | /* Per-cpu buffer size: backend */ | |
265 | /* num_subbuf + 1 is the worse case */ | |
266 | num_subbuf_alloc = num_subbuf + 1; | |
4cfec15c MD |
267 | shmsize += offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages_shmp)); |
268 | shmsize += sizeof(struct lttng_ust_lib_ring_buffer_backend_pages_shmp) * num_subbuf_alloc; | |
6c1f7d8b | 269 | shmsize += offset_align(shmsize, PAGE_SIZE); |
1d498196 | 270 | shmsize += subbuf_size * num_subbuf_alloc; |
4cfec15c MD |
271 | shmsize += offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages)); |
272 | shmsize += sizeof(struct lttng_ust_lib_ring_buffer_backend_pages) * num_subbuf_alloc; | |
273 | shmsize += offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer_backend_subbuffer)); | |
274 | shmsize += sizeof(struct lttng_ust_lib_ring_buffer_backend_subbuffer) * num_subbuf; | |
1d498196 MD |
275 | /* Per-cpu buffer size: control (after backend) */ |
276 | shmsize += offset_align(shmsize, __alignof__(struct commit_counters_hot)); | |
277 | shmsize += sizeof(struct commit_counters_hot) * num_subbuf; | |
278 | shmsize += offset_align(shmsize, __alignof__(struct commit_counters_cold)); | |
279 | shmsize += sizeof(struct commit_counters_cold) * num_subbuf; | |
280 | ||
852c2936 | 281 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) { |
4cfec15c | 282 | struct lttng_ust_lib_ring_buffer *buf; |
852c2936 | 283 | /* |
a6352fd4 | 284 | * We need to allocate for all possible cpus. |
852c2936 | 285 | */ |
852c2936 | 286 | for_each_possible_cpu(i) { |
1d498196 MD |
287 | struct shm_object *shmobj; |
288 | ||
74d81a6c MD |
289 | shmobj = shm_object_table_alloc(handle->table, shmsize, |
290 | SHM_OBJECT_SHM); | |
afdf9825 MD |
291 | if (!shmobj) |
292 | goto end; | |
4cfec15c MD |
293 | align_shm(shmobj, __alignof__(struct lttng_ust_lib_ring_buffer)); |
294 | set_shmp(chanb->buf[i].shmp, zalloc_shm(shmobj, sizeof(struct lttng_ust_lib_ring_buffer))); | |
1d498196 MD |
295 | buf = shmp(handle, chanb->buf[i].shmp); |
296 | if (!buf) | |
297 | goto end; | |
5d61a504 | 298 | set_shmp(buf->self, chanb->buf[i].shmp._ref); |
1d498196 MD |
299 | ret = lib_ring_buffer_create(buf, chanb, i, |
300 | handle, shmobj); | |
852c2936 MD |
301 | if (ret) |
302 | goto free_bufs; /* cpu hotplug locked */ | |
303 | } | |
852c2936 | 304 | } else { |
1d498196 | 305 | struct shm_object *shmobj; |
4cfec15c | 306 | struct lttng_ust_lib_ring_buffer *buf; |
a6352fd4 | 307 | |
74d81a6c MD |
308 | shmobj = shm_object_table_alloc(handle->table, shmsize, |
309 | SHM_OBJECT_SHM); | |
afdf9825 MD |
310 | if (!shmobj) |
311 | goto end; | |
4cfec15c MD |
312 | align_shm(shmobj, __alignof__(struct lttng_ust_lib_ring_buffer)); |
313 | set_shmp(chanb->buf[0].shmp, zalloc_shm(shmobj, sizeof(struct lttng_ust_lib_ring_buffer))); | |
1d498196 | 314 | buf = shmp(handle, chanb->buf[0].shmp); |
a6352fd4 MD |
315 | if (!buf) |
316 | goto end; | |
cb14bae9 | 317 | set_shmp(buf->self, chanb->buf[0].shmp._ref); |
1d498196 MD |
318 | ret = lib_ring_buffer_create(buf, chanb, -1, |
319 | handle, shmobj); | |
852c2936 MD |
320 | if (ret) |
321 | goto free_bufs; | |
322 | } | |
323 | chanb->start_tsc = config->cb.ring_buffer_clock_read(chan); | |
324 | ||
325 | return 0; | |
326 | ||
327 | free_bufs: | |
a6352fd4 MD |
328 | /* We only free the buffer data upon shm teardown */ |
329 | end: | |
852c2936 MD |
330 | return -ENOMEM; |
331 | } | |
332 | ||
852c2936 MD |
333 | /** |
334 | * channel_backend_free - destroy the channel | |
335 | * @chan: the channel | |
336 | * | |
337 | * Destroy all channel buffers and frees the channel. | |
338 | */ | |
1d498196 | 339 | void channel_backend_free(struct channel_backend *chanb, |
38fae1d3 | 340 | struct lttng_ust_shm_handle *handle) |
852c2936 | 341 | { |
45e9e699 | 342 | /* SHM teardown takes care of everything */ |
852c2936 MD |
343 | } |
344 | ||
852c2936 MD |
345 | /** |
346 | * lib_ring_buffer_read - read data from ring_buffer_buffer. | |
347 | * @bufb : buffer backend | |
348 | * @offset : offset within the buffer | |
349 | * @dest : destination address | |
350 | * @len : length to copy to destination | |
351 | * | |
352 | * Should be protected by get_subbuf/put_subbuf. | |
353 | * Returns the length copied. | |
354 | */ | |
4cfec15c | 355 | size_t lib_ring_buffer_read(struct lttng_ust_lib_ring_buffer_backend *bufb, size_t offset, |
38fae1d3 | 356 | void *dest, size_t len, struct lttng_ust_shm_handle *handle) |
852c2936 | 357 | { |
1d498196 | 358 | struct channel_backend *chanb = &shmp(handle, bufb->chan)->backend; |
4cfec15c | 359 | const struct lttng_ust_lib_ring_buffer_config *config = &chanb->config; |
a6352fd4 | 360 | ssize_t orig_len; |
4cfec15c | 361 | struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages; |
852c2936 MD |
362 | unsigned long sb_bindex, id; |
363 | ||
364 | orig_len = len; | |
365 | offset &= chanb->buf_size - 1; | |
a6352fd4 | 366 | |
b5a3dfa5 | 367 | if (caa_unlikely(!len)) |
852c2936 | 368 | return 0; |
a6352fd4 MD |
369 | id = bufb->buf_rsb.id; |
370 | sb_bindex = subbuffer_id_get_index(config, id); | |
4746ae29 | 371 | rpages = shmp_index(handle, bufb->array, sb_bindex); |
a6352fd4 MD |
372 | /* |
373 | * Underlying layer should never ask for reads across | |
374 | * subbuffers. | |
375 | */ | |
376 | CHAN_WARN_ON(chanb, offset >= chanb->buf_size); | |
377 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE | |
378 | && subbuffer_id_is_noref(config, id)); | |
aead2025 | 379 | memcpy(dest, shmp_index(handle, shmp(handle, rpages->shmp)->p, offset & (chanb->subbuf_size - 1)), len); |
852c2936 MD |
380 | return orig_len; |
381 | } | |
852c2936 | 382 | |
852c2936 MD |
383 | /** |
384 | * lib_ring_buffer_read_cstr - read a C-style string from ring_buffer. | |
385 | * @bufb : buffer backend | |
386 | * @offset : offset within the buffer | |
387 | * @dest : destination address | |
388 | * @len : destination's length | |
389 | * | |
0bf3c920 | 390 | * Return string's length, or -EINVAL on error. |
852c2936 | 391 | * Should be protected by get_subbuf/put_subbuf. |
0bf3c920 | 392 | * Destination length should be at least 1 to hold '\0'. |
852c2936 | 393 | */ |
4cfec15c | 394 | int lib_ring_buffer_read_cstr(struct lttng_ust_lib_ring_buffer_backend *bufb, size_t offset, |
38fae1d3 | 395 | void *dest, size_t len, struct lttng_ust_shm_handle *handle) |
852c2936 | 396 | { |
1d498196 | 397 | struct channel_backend *chanb = &shmp(handle, bufb->chan)->backend; |
4cfec15c | 398 | const struct lttng_ust_lib_ring_buffer_config *config = &chanb->config; |
a6352fd4 | 399 | ssize_t string_len, orig_offset; |
852c2936 | 400 | char *str; |
4cfec15c | 401 | struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages; |
852c2936 MD |
402 | unsigned long sb_bindex, id; |
403 | ||
0bf3c920 MD |
404 | if (caa_unlikely(!len)) |
405 | return -EINVAL; | |
852c2936 | 406 | offset &= chanb->buf_size - 1; |
852c2936 | 407 | orig_offset = offset; |
852c2936 MD |
408 | id = bufb->buf_rsb.id; |
409 | sb_bindex = subbuffer_id_get_index(config, id); | |
4746ae29 | 410 | rpages = shmp_index(handle, bufb->array, sb_bindex); |
a6352fd4 MD |
411 | /* |
412 | * Underlying layer should never ask for reads across | |
413 | * subbuffers. | |
414 | */ | |
415 | CHAN_WARN_ON(chanb, offset >= chanb->buf_size); | |
852c2936 MD |
416 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE |
417 | && subbuffer_id_is_noref(config, id)); | |
aead2025 | 418 | str = shmp_index(handle, shmp(handle, rpages->shmp)->p, offset & (chanb->subbuf_size - 1)); |
a6352fd4 MD |
419 | string_len = strnlen(str, len); |
420 | if (dest && len) { | |
421 | memcpy(dest, str, string_len); | |
422 | ((char *)dest)[0] = 0; | |
423 | } | |
424 | return offset - orig_offset; | |
852c2936 | 425 | } |
852c2936 MD |
426 | |
427 | /** | |
428 | * lib_ring_buffer_read_offset_address - get address of a buffer location | |
429 | * @bufb : buffer backend | |
430 | * @offset : offset within the buffer. | |
431 | * | |
432 | * Return the address where a given offset is located (for read). | |
433 | * Should be used to get the current subbuffer header pointer. Given we know | |
22b22ce9 MD |
434 | * it's never on a page boundary, it's safe to read/write directly |
435 | * from/to this address, as long as the read/write is never bigger than | |
436 | * a page size. | |
852c2936 | 437 | */ |
4cfec15c | 438 | void *lib_ring_buffer_read_offset_address(struct lttng_ust_lib_ring_buffer_backend *bufb, |
1d498196 | 439 | size_t offset, |
38fae1d3 | 440 | struct lttng_ust_shm_handle *handle) |
852c2936 | 441 | { |
4cfec15c | 442 | struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages; |
1d498196 | 443 | struct channel_backend *chanb = &shmp(handle, bufb->chan)->backend; |
4cfec15c | 444 | const struct lttng_ust_lib_ring_buffer_config *config = &chanb->config; |
852c2936 MD |
445 | unsigned long sb_bindex, id; |
446 | ||
447 | offset &= chanb->buf_size - 1; | |
852c2936 MD |
448 | id = bufb->buf_rsb.id; |
449 | sb_bindex = subbuffer_id_get_index(config, id); | |
4746ae29 | 450 | rpages = shmp_index(handle, bufb->array, sb_bindex); |
852c2936 MD |
451 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE |
452 | && subbuffer_id_is_noref(config, id)); | |
aead2025 | 453 | return shmp_index(handle, shmp(handle, rpages->shmp)->p, offset & (chanb->subbuf_size - 1)); |
852c2936 | 454 | } |
852c2936 MD |
455 | |
456 | /** | |
457 | * lib_ring_buffer_offset_address - get address of a location within the buffer | |
458 | * @bufb : buffer backend | |
459 | * @offset : offset within the buffer. | |
460 | * | |
461 | * Return the address where a given offset is located. | |
462 | * Should be used to get the current subbuffer header pointer. Given we know | |
463 | * it's always at the beginning of a page, it's safe to write directly to this | |
464 | * address, as long as the write is never bigger than a page size. | |
465 | */ | |
4cfec15c | 466 | void *lib_ring_buffer_offset_address(struct lttng_ust_lib_ring_buffer_backend *bufb, |
1d498196 | 467 | size_t offset, |
38fae1d3 | 468 | struct lttng_ust_shm_handle *handle) |
852c2936 | 469 | { |
a6352fd4 | 470 | size_t sbidx; |
4cfec15c | 471 | struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages; |
1d498196 | 472 | struct channel_backend *chanb = &shmp(handle, bufb->chan)->backend; |
4cfec15c | 473 | const struct lttng_ust_lib_ring_buffer_config *config = &chanb->config; |
852c2936 MD |
474 | unsigned long sb_bindex, id; |
475 | ||
476 | offset &= chanb->buf_size - 1; | |
477 | sbidx = offset >> chanb->subbuf_size_order; | |
4746ae29 | 478 | id = shmp_index(handle, bufb->buf_wsb, sbidx)->id; |
852c2936 | 479 | sb_bindex = subbuffer_id_get_index(config, id); |
4746ae29 | 480 | rpages = shmp_index(handle, bufb->array, sb_bindex); |
852c2936 MD |
481 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE |
482 | && subbuffer_id_is_noref(config, id)); | |
aead2025 | 483 | return shmp_index(handle, shmp(handle, rpages->shmp)->p, offset & (chanb->subbuf_size - 1)); |
852c2936 | 484 | } |