Commit | Line | Data |
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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" | |
852c2936 MD |
16 | |
17 | /** | |
18 | * lib_ring_buffer_backend_allocate - allocate a channel buffer | |
19 | * @config: ring buffer instance configuration | |
20 | * @buf: the buffer struct | |
21 | * @size: total size of the buffer | |
22 | * @num_subbuf: number of subbuffers | |
23 | * @extra_reader_sb: need extra subbuffer for reader | |
24 | */ | |
25 | static | |
26 | int lib_ring_buffer_backend_allocate(const struct lib_ring_buffer_config *config, | |
27 | struct lib_ring_buffer_backend *bufb, | |
28 | size_t size, size_t num_subbuf, | |
29 | int extra_reader_sb) | |
30 | { | |
31 | struct channel_backend *chanb = &bufb->chan->backend; | |
32 | unsigned long j, num_pages, num_pages_per_subbuf, page_idx = 0; | |
33 | unsigned long subbuf_size, mmap_offset = 0; | |
34 | unsigned long num_subbuf_alloc; | |
35 | struct page **pages; | |
36 | void **virt; | |
37 | unsigned long i; | |
38 | ||
14641deb | 39 | num_pages = size >> get_count_order(PAGE_SIZE); |
852c2936 MD |
40 | num_pages_per_subbuf = num_pages >> get_count_order(num_subbuf); |
41 | subbuf_size = chanb->subbuf_size; | |
42 | num_subbuf_alloc = num_subbuf; | |
43 | ||
44 | if (extra_reader_sb) { | |
45 | num_pages += num_pages_per_subbuf; /* Add pages for reader */ | |
46 | num_subbuf_alloc++; | |
47 | } | |
48 | ||
14641deb | 49 | pages = malloc_align(sizeof(*pages) * num_pages); |
852c2936 MD |
50 | if (unlikely(!pages)) |
51 | goto pages_error; | |
52 | ||
14641deb | 53 | virt = malloc_align(sizeof(*virt) * num_pages); |
852c2936 MD |
54 | if (unlikely(!virt)) |
55 | goto virt_error; | |
56 | ||
14641deb | 57 | bufb->array = malloc_align(sizeof(*bufb->array) * num_subbuf_alloc); |
852c2936 MD |
58 | if (unlikely(!bufb->array)) |
59 | goto array_error; | |
60 | ||
61 | for (i = 0; i < num_pages; i++) { | |
62 | pages[i] = alloc_pages_node(cpu_to_node(max(bufb->cpu, 0)), | |
63 | GFP_KERNEL | __GFP_ZERO, 0); | |
64 | if (unlikely(!pages[i])) | |
65 | goto depopulate; | |
66 | virt[i] = page_address(pages[i]); | |
67 | } | |
68 | bufb->num_pages_per_subbuf = num_pages_per_subbuf; | |
69 | ||
70 | /* Allocate backend pages array elements */ | |
71 | for (i = 0; i < num_subbuf_alloc; i++) { | |
72 | bufb->array[i] = | |
14641deb | 73 | zmalloc_align( |
852c2936 MD |
74 | sizeof(struct lib_ring_buffer_backend_pages) + |
75 | sizeof(struct lib_ring_buffer_backend_page) | |
14641deb | 76 | * num_pages_per_subbuf); |
852c2936 MD |
77 | if (!bufb->array[i]) |
78 | goto free_array; | |
79 | } | |
80 | ||
81 | /* Allocate write-side subbuffer table */ | |
14641deb | 82 | bufb->buf_wsb = zmalloc_align( |
852c2936 | 83 | sizeof(struct lib_ring_buffer_backend_subbuffer) |
14641deb | 84 | * num_subbuf); |
852c2936 MD |
85 | if (unlikely(!bufb->buf_wsb)) |
86 | goto free_array; | |
87 | ||
88 | for (i = 0; i < num_subbuf; i++) | |
89 | bufb->buf_wsb[i].id = subbuffer_id(config, 0, 1, i); | |
90 | ||
91 | /* Assign read-side subbuffer table */ | |
92 | if (extra_reader_sb) | |
93 | bufb->buf_rsb.id = subbuffer_id(config, 0, 1, | |
94 | num_subbuf_alloc - 1); | |
95 | else | |
96 | bufb->buf_rsb.id = subbuffer_id(config, 0, 1, 0); | |
97 | ||
98 | /* Assign pages to page index */ | |
99 | for (i = 0; i < num_subbuf_alloc; i++) { | |
100 | for (j = 0; j < num_pages_per_subbuf; j++) { | |
101 | CHAN_WARN_ON(chanb, page_idx > num_pages); | |
102 | bufb->array[i]->p[j].virt = virt[page_idx]; | |
103 | bufb->array[i]->p[j].page = pages[page_idx]; | |
104 | page_idx++; | |
105 | } | |
106 | if (config->output == RING_BUFFER_MMAP) { | |
107 | bufb->array[i]->mmap_offset = mmap_offset; | |
108 | mmap_offset += subbuf_size; | |
109 | } | |
110 | } | |
111 | ||
852c2936 MD |
112 | kfree(virt); |
113 | kfree(pages); | |
114 | return 0; | |
115 | ||
116 | free_array: | |
117 | for (i = 0; (i < num_subbuf_alloc && bufb->array[i]); i++) | |
118 | kfree(bufb->array[i]); | |
119 | depopulate: | |
120 | /* Free all allocated pages */ | |
121 | for (i = 0; (i < num_pages && pages[i]); i++) | |
122 | __free_page(pages[i]); | |
123 | kfree(bufb->array); | |
124 | array_error: | |
125 | kfree(virt); | |
126 | virt_error: | |
127 | kfree(pages); | |
128 | pages_error: | |
129 | return -ENOMEM; | |
130 | } | |
131 | ||
132 | int lib_ring_buffer_backend_create(struct lib_ring_buffer_backend *bufb, | |
133 | struct channel_backend *chanb, int cpu) | |
134 | { | |
135 | const struct lib_ring_buffer_config *config = chanb->config; | |
136 | ||
14641deb | 137 | bufb->chan = caa_container_of(chanb, struct channel, backend); |
852c2936 MD |
138 | bufb->cpu = cpu; |
139 | ||
140 | return lib_ring_buffer_backend_allocate(config, bufb, chanb->buf_size, | |
141 | chanb->num_subbuf, | |
142 | chanb->extra_reader_sb); | |
143 | } | |
144 | ||
145 | void lib_ring_buffer_backend_free(struct lib_ring_buffer_backend *bufb) | |
146 | { | |
147 | struct channel_backend *chanb = &bufb->chan->backend; | |
148 | unsigned long i, j, num_subbuf_alloc; | |
149 | ||
150 | num_subbuf_alloc = chanb->num_subbuf; | |
151 | if (chanb->extra_reader_sb) | |
152 | num_subbuf_alloc++; | |
153 | ||
154 | kfree(bufb->buf_wsb); | |
155 | for (i = 0; i < num_subbuf_alloc; i++) { | |
156 | for (j = 0; j < bufb->num_pages_per_subbuf; j++) | |
157 | __free_page(bufb->array[i]->p[j].page); | |
158 | kfree(bufb->array[i]); | |
159 | } | |
160 | kfree(bufb->array); | |
161 | bufb->allocated = 0; | |
162 | } | |
163 | ||
164 | void lib_ring_buffer_backend_reset(struct lib_ring_buffer_backend *bufb) | |
165 | { | |
166 | struct channel_backend *chanb = &bufb->chan->backend; | |
167 | const struct lib_ring_buffer_config *config = chanb->config; | |
168 | unsigned long num_subbuf_alloc; | |
169 | unsigned int i; | |
170 | ||
171 | num_subbuf_alloc = chanb->num_subbuf; | |
172 | if (chanb->extra_reader_sb) | |
173 | num_subbuf_alloc++; | |
174 | ||
175 | for (i = 0; i < chanb->num_subbuf; i++) | |
176 | bufb->buf_wsb[i].id = subbuffer_id(config, 0, 1, i); | |
177 | if (chanb->extra_reader_sb) | |
178 | bufb->buf_rsb.id = subbuffer_id(config, 0, 1, | |
179 | num_subbuf_alloc - 1); | |
180 | else | |
181 | bufb->buf_rsb.id = subbuffer_id(config, 0, 1, 0); | |
182 | ||
183 | for (i = 0; i < num_subbuf_alloc; i++) { | |
184 | /* Don't reset mmap_offset */ | |
185 | v_set(config, &bufb->array[i]->records_commit, 0); | |
186 | v_set(config, &bufb->array[i]->records_unread, 0); | |
187 | bufb->array[i]->data_size = 0; | |
188 | /* Don't reset backend page and virt addresses */ | |
189 | } | |
190 | /* Don't reset num_pages_per_subbuf, cpu, allocated */ | |
191 | v_set(config, &bufb->records_read, 0); | |
192 | } | |
193 | ||
194 | /* | |
195 | * The frontend is responsible for also calling ring_buffer_backend_reset for | |
196 | * each buffer when calling channel_backend_reset. | |
197 | */ | |
198 | void channel_backend_reset(struct channel_backend *chanb) | |
199 | { | |
14641deb | 200 | struct channel *chan = caa_container_of(chanb, struct channel, backend); |
852c2936 MD |
201 | const struct lib_ring_buffer_config *config = chanb->config; |
202 | ||
203 | /* | |
204 | * Don't reset buf_size, subbuf_size, subbuf_size_order, | |
205 | * num_subbuf_order, buf_size_order, extra_reader_sb, num_subbuf, | |
206 | * priv, notifiers, config, cpumask and name. | |
207 | */ | |
208 | chanb->start_tsc = config->cb.ring_buffer_clock_read(chan); | |
209 | } | |
210 | ||
211 | #ifdef CONFIG_HOTPLUG_CPU | |
212 | /** | |
213 | * lib_ring_buffer_cpu_hp_callback - CPU hotplug callback | |
214 | * @nb: notifier block | |
215 | * @action: hotplug action to take | |
216 | * @hcpu: CPU number | |
217 | * | |
218 | * Returns the success/failure of the operation. (%NOTIFY_OK, %NOTIFY_BAD) | |
219 | */ | |
220 | static | |
221 | int __cpuinit lib_ring_buffer_cpu_hp_callback(struct notifier_block *nb, | |
222 | unsigned long action, | |
223 | void *hcpu) | |
224 | { | |
225 | unsigned int cpu = (unsigned long)hcpu; | |
14641deb | 226 | struct channel_backend *chanb = caa_container_of(nb, struct channel_backend, |
852c2936 MD |
227 | cpu_hp_notifier); |
228 | const struct lib_ring_buffer_config *config = chanb->config; | |
229 | struct lib_ring_buffer *buf; | |
230 | int ret; | |
231 | ||
232 | CHAN_WARN_ON(chanb, config->alloc == RING_BUFFER_ALLOC_GLOBAL); | |
233 | ||
234 | switch (action) { | |
235 | case CPU_UP_PREPARE: | |
236 | case CPU_UP_PREPARE_FROZEN: | |
237 | buf = per_cpu_ptr(chanb->buf, cpu); | |
238 | ret = lib_ring_buffer_create(buf, chanb, cpu); | |
239 | if (ret) { | |
240 | printk(KERN_ERR | |
241 | "ring_buffer_cpu_hp_callback: cpu %d " | |
242 | "buffer creation failed\n", cpu); | |
243 | return NOTIFY_BAD; | |
244 | } | |
245 | break; | |
246 | case CPU_DEAD: | |
247 | case CPU_DEAD_FROZEN: | |
248 | /* No need to do a buffer switch here, because it will happen | |
249 | * when tracing is stopped, or will be done by switch timer CPU | |
250 | * DEAD callback. */ | |
251 | break; | |
252 | } | |
253 | return NOTIFY_OK; | |
254 | } | |
255 | #endif | |
256 | ||
257 | /** | |
258 | * channel_backend_init - initialize a channel backend | |
259 | * @chanb: channel backend | |
260 | * @name: channel name | |
261 | * @config: client ring buffer configuration | |
262 | * @priv: client private data | |
263 | * @parent: dentry of parent directory, %NULL for root directory | |
264 | * @subbuf_size: size of sub-buffers (> PAGE_SIZE, power of 2) | |
265 | * @num_subbuf: number of sub-buffers (power of 2) | |
266 | * | |
267 | * Returns channel pointer if successful, %NULL otherwise. | |
268 | * | |
269 | * Creates per-cpu channel buffers using the sizes and attributes | |
270 | * specified. The created channel buffer files will be named | |
271 | * name_0...name_N-1. File permissions will be %S_IRUSR. | |
272 | * | |
273 | * Called with CPU hotplug disabled. | |
274 | */ | |
275 | int channel_backend_init(struct channel_backend *chanb, | |
276 | const char *name, | |
277 | const struct lib_ring_buffer_config *config, | |
278 | void *priv, size_t subbuf_size, size_t num_subbuf) | |
279 | { | |
14641deb | 280 | struct channel *chan = caa_container_of(chanb, struct channel, backend); |
852c2936 MD |
281 | unsigned int i; |
282 | int ret; | |
283 | ||
284 | if (!name) | |
285 | return -EPERM; | |
286 | ||
287 | if (!(subbuf_size && num_subbuf)) | |
288 | return -EPERM; | |
289 | ||
290 | /* Check that the subbuffer size is larger than a page. */ | |
291 | if (subbuf_size < PAGE_SIZE) | |
292 | return -EINVAL; | |
293 | ||
294 | /* | |
295 | * Make sure the number of subbuffers and subbuffer size are power of 2. | |
296 | */ | |
297 | CHAN_WARN_ON(chanb, hweight32(subbuf_size) != 1); | |
298 | CHAN_WARN_ON(chanb, hweight32(num_subbuf) != 1); | |
299 | ||
300 | ret = subbuffer_id_check_index(config, num_subbuf); | |
301 | if (ret) | |
302 | return ret; | |
303 | ||
304 | chanb->priv = priv; | |
305 | chanb->buf_size = num_subbuf * subbuf_size; | |
306 | chanb->subbuf_size = subbuf_size; | |
307 | chanb->buf_size_order = get_count_order(chanb->buf_size); | |
308 | chanb->subbuf_size_order = get_count_order(subbuf_size); | |
309 | chanb->num_subbuf_order = get_count_order(num_subbuf); | |
310 | chanb->extra_reader_sb = | |
311 | (config->mode == RING_BUFFER_OVERWRITE) ? 1 : 0; | |
312 | chanb->num_subbuf = num_subbuf; | |
313 | strlcpy(chanb->name, name, NAME_MAX); | |
314 | chanb->config = config; | |
315 | ||
316 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) { | |
317 | if (!zalloc_cpumask_var(&chanb->cpumask, GFP_KERNEL)) | |
318 | return -ENOMEM; | |
319 | } | |
320 | ||
321 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) { | |
322 | /* Allocating the buffer per-cpu structures */ | |
323 | chanb->buf = alloc_percpu(struct lib_ring_buffer); | |
324 | if (!chanb->buf) | |
325 | goto free_cpumask; | |
326 | ||
327 | /* | |
328 | * In case of non-hotplug cpu, if the ring-buffer is allocated | |
329 | * in early initcall, it will not be notified of secondary cpus. | |
330 | * In that off case, we need to allocate for all possible cpus. | |
331 | */ | |
332 | #ifdef CONFIG_HOTPLUG_CPU | |
333 | /* | |
334 | * buf->backend.allocated test takes care of concurrent CPU | |
335 | * hotplug. | |
336 | * Priority higher than frontend, so we create the ring buffer | |
337 | * before we start the timer. | |
338 | */ | |
339 | chanb->cpu_hp_notifier.notifier_call = | |
340 | lib_ring_buffer_cpu_hp_callback; | |
341 | chanb->cpu_hp_notifier.priority = 5; | |
342 | register_hotcpu_notifier(&chanb->cpu_hp_notifier); | |
343 | ||
344 | get_online_cpus(); | |
345 | for_each_online_cpu(i) { | |
346 | ret = lib_ring_buffer_create(per_cpu_ptr(chanb->buf, i), | |
347 | chanb, i); | |
348 | if (ret) | |
349 | goto free_bufs; /* cpu hotplug locked */ | |
350 | } | |
351 | put_online_cpus(); | |
352 | #else | |
353 | for_each_possible_cpu(i) { | |
354 | ret = lib_ring_buffer_create(per_cpu_ptr(chanb->buf, i), | |
355 | chanb, i); | |
356 | if (ret) | |
357 | goto free_bufs; /* cpu hotplug locked */ | |
358 | } | |
359 | #endif | |
360 | } else { | |
361 | chanb->buf = kzalloc(sizeof(struct lib_ring_buffer), GFP_KERNEL); | |
362 | if (!chanb->buf) | |
363 | goto free_cpumask; | |
364 | ret = lib_ring_buffer_create(chanb->buf, chanb, -1); | |
365 | if (ret) | |
366 | goto free_bufs; | |
367 | } | |
368 | chanb->start_tsc = config->cb.ring_buffer_clock_read(chan); | |
369 | ||
370 | return 0; | |
371 | ||
372 | free_bufs: | |
373 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) { | |
374 | for_each_possible_cpu(i) { | |
375 | struct lib_ring_buffer *buf = per_cpu_ptr(chanb->buf, i); | |
376 | ||
377 | if (!buf->backend.allocated) | |
378 | continue; | |
379 | lib_ring_buffer_free(buf); | |
380 | } | |
381 | #ifdef CONFIG_HOTPLUG_CPU | |
382 | put_online_cpus(); | |
383 | #endif | |
384 | free_percpu(chanb->buf); | |
385 | } else | |
386 | kfree(chanb->buf); | |
387 | free_cpumask: | |
388 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) | |
389 | free_cpumask_var(chanb->cpumask); | |
390 | return -ENOMEM; | |
391 | } | |
392 | ||
393 | /** | |
394 | * channel_backend_unregister_notifiers - unregister notifiers | |
395 | * @chan: the channel | |
396 | * | |
397 | * Holds CPU hotplug. | |
398 | */ | |
399 | void channel_backend_unregister_notifiers(struct channel_backend *chanb) | |
400 | { | |
401 | const struct lib_ring_buffer_config *config = chanb->config; | |
402 | ||
403 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) | |
404 | unregister_hotcpu_notifier(&chanb->cpu_hp_notifier); | |
405 | } | |
406 | ||
407 | /** | |
408 | * channel_backend_free - destroy the channel | |
409 | * @chan: the channel | |
410 | * | |
411 | * Destroy all channel buffers and frees the channel. | |
412 | */ | |
413 | void channel_backend_free(struct channel_backend *chanb) | |
414 | { | |
415 | const struct lib_ring_buffer_config *config = chanb->config; | |
416 | unsigned int i; | |
417 | ||
418 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) { | |
419 | for_each_possible_cpu(i) { | |
420 | struct lib_ring_buffer *buf = per_cpu_ptr(chanb->buf, i); | |
421 | ||
422 | if (!buf->backend.allocated) | |
423 | continue; | |
424 | lib_ring_buffer_free(buf); | |
425 | } | |
426 | free_cpumask_var(chanb->cpumask); | |
427 | free_percpu(chanb->buf); | |
428 | } else { | |
429 | struct lib_ring_buffer *buf = chanb->buf; | |
430 | ||
431 | CHAN_WARN_ON(chanb, !buf->backend.allocated); | |
432 | lib_ring_buffer_free(buf); | |
433 | kfree(buf); | |
434 | } | |
435 | } | |
436 | ||
437 | /** | |
438 | * lib_ring_buffer_write - write data to a ring_buffer buffer. | |
439 | * @bufb : buffer backend | |
440 | * @offset : offset within the buffer | |
441 | * @src : source address | |
442 | * @len : length to write | |
443 | * @pagecpy : page size copied so far | |
444 | */ | |
445 | void _lib_ring_buffer_write(struct lib_ring_buffer_backend *bufb, size_t offset, | |
446 | const void *src, size_t len, ssize_t pagecpy) | |
447 | { | |
448 | struct channel_backend *chanb = &bufb->chan->backend; | |
449 | const struct lib_ring_buffer_config *config = chanb->config; | |
450 | size_t sbidx, index; | |
451 | struct lib_ring_buffer_backend_pages *rpages; | |
452 | unsigned long sb_bindex, id; | |
453 | ||
454 | do { | |
455 | len -= pagecpy; | |
456 | src += pagecpy; | |
457 | offset += pagecpy; | |
458 | sbidx = offset >> chanb->subbuf_size_order; | |
14641deb | 459 | index = (offset & (chanb->subbuf_size - 1)) >> get_count_order(PAGE_SIZE); |
852c2936 MD |
460 | |
461 | /* | |
462 | * Underlying layer should never ask for writes across | |
463 | * subbuffers. | |
464 | */ | |
465 | CHAN_WARN_ON(chanb, offset >= chanb->buf_size); | |
466 | ||
467 | pagecpy = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK)); | |
468 | id = bufb->buf_wsb[sbidx].id; | |
469 | sb_bindex = subbuffer_id_get_index(config, id); | |
470 | rpages = bufb->array[sb_bindex]; | |
471 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE | |
472 | && subbuffer_id_is_noref(config, id)); | |
473 | lib_ring_buffer_do_copy(config, | |
474 | rpages->p[index].virt | |
475 | + (offset & ~PAGE_MASK), | |
476 | src, pagecpy); | |
477 | } while (unlikely(len != pagecpy)); | |
478 | } | |
479 | EXPORT_SYMBOL_GPL(_lib_ring_buffer_write); | |
480 | ||
481 | /** | |
482 | * lib_ring_buffer_read - read data from ring_buffer_buffer. | |
483 | * @bufb : buffer backend | |
484 | * @offset : offset within the buffer | |
485 | * @dest : destination address | |
486 | * @len : length to copy to destination | |
487 | * | |
488 | * Should be protected by get_subbuf/put_subbuf. | |
489 | * Returns the length copied. | |
490 | */ | |
491 | size_t lib_ring_buffer_read(struct lib_ring_buffer_backend *bufb, size_t offset, | |
492 | void *dest, size_t len) | |
493 | { | |
494 | struct channel_backend *chanb = &bufb->chan->backend; | |
495 | const struct lib_ring_buffer_config *config = chanb->config; | |
496 | size_t index; | |
497 | ssize_t pagecpy, orig_len; | |
498 | struct lib_ring_buffer_backend_pages *rpages; | |
499 | unsigned long sb_bindex, id; | |
500 | ||
501 | orig_len = len; | |
502 | offset &= chanb->buf_size - 1; | |
14641deb | 503 | index = (offset & (chanb->subbuf_size - 1)) >> get_count_order(PAGE_SIZE); |
852c2936 MD |
504 | if (unlikely(!len)) |
505 | return 0; | |
506 | for (;;) { | |
507 | pagecpy = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK)); | |
508 | id = bufb->buf_rsb.id; | |
509 | sb_bindex = subbuffer_id_get_index(config, id); | |
510 | rpages = bufb->array[sb_bindex]; | |
511 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE | |
512 | && subbuffer_id_is_noref(config, id)); | |
513 | memcpy(dest, rpages->p[index].virt + (offset & ~PAGE_MASK), | |
514 | pagecpy); | |
515 | len -= pagecpy; | |
516 | if (likely(!len)) | |
517 | break; | |
518 | dest += pagecpy; | |
519 | offset += pagecpy; | |
14641deb | 520 | index = (offset & (chanb->subbuf_size - 1)) >> get_count_order(PAGE_SIZE); |
852c2936 MD |
521 | /* |
522 | * Underlying layer should never ask for reads across | |
523 | * subbuffers. | |
524 | */ | |
525 | CHAN_WARN_ON(chanb, offset >= chanb->buf_size); | |
526 | } | |
527 | return orig_len; | |
528 | } | |
529 | EXPORT_SYMBOL_GPL(lib_ring_buffer_read); | |
530 | ||
852c2936 MD |
531 | /** |
532 | * lib_ring_buffer_read_cstr - read a C-style string from ring_buffer. | |
533 | * @bufb : buffer backend | |
534 | * @offset : offset within the buffer | |
535 | * @dest : destination address | |
536 | * @len : destination's length | |
537 | * | |
538 | * return string's length | |
539 | * Should be protected by get_subbuf/put_subbuf. | |
540 | */ | |
541 | int lib_ring_buffer_read_cstr(struct lib_ring_buffer_backend *bufb, size_t offset, | |
542 | void *dest, size_t len) | |
543 | { | |
544 | struct channel_backend *chanb = &bufb->chan->backend; | |
545 | const struct lib_ring_buffer_config *config = chanb->config; | |
546 | size_t index; | |
547 | ssize_t pagecpy, pagelen, strpagelen, orig_offset; | |
548 | char *str; | |
549 | struct lib_ring_buffer_backend_pages *rpages; | |
550 | unsigned long sb_bindex, id; | |
551 | ||
552 | offset &= chanb->buf_size - 1; | |
14641deb | 553 | index = (offset & (chanb->subbuf_size - 1)) >> get_count_order(PAGE_SIZE); |
852c2936 MD |
554 | orig_offset = offset; |
555 | for (;;) { | |
556 | id = bufb->buf_rsb.id; | |
557 | sb_bindex = subbuffer_id_get_index(config, id); | |
558 | rpages = bufb->array[sb_bindex]; | |
559 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE | |
560 | && subbuffer_id_is_noref(config, id)); | |
561 | str = (char *)rpages->p[index].virt + (offset & ~PAGE_MASK); | |
562 | pagelen = PAGE_SIZE - (offset & ~PAGE_MASK); | |
563 | strpagelen = strnlen(str, pagelen); | |
564 | if (len) { | |
565 | pagecpy = min_t(size_t, len, strpagelen); | |
566 | if (dest) { | |
567 | memcpy(dest, str, pagecpy); | |
568 | dest += pagecpy; | |
569 | } | |
570 | len -= pagecpy; | |
571 | } | |
572 | offset += strpagelen; | |
14641deb | 573 | index = (offset & (chanb->subbuf_size - 1)) >> get_count_order(PAGE_SIZE); |
852c2936 MD |
574 | if (strpagelen < pagelen) |
575 | break; | |
576 | /* | |
577 | * Underlying layer should never ask for reads across | |
578 | * subbuffers. | |
579 | */ | |
580 | CHAN_WARN_ON(chanb, offset >= chanb->buf_size); | |
581 | } | |
582 | if (dest && len) | |
583 | ((char *)dest)[0] = 0; | |
584 | return offset - orig_offset; | |
585 | } | |
586 | EXPORT_SYMBOL_GPL(lib_ring_buffer_read_cstr); | |
587 | ||
588 | /** | |
589 | * lib_ring_buffer_read_get_page - Get a whole page to read from | |
590 | * @bufb : buffer backend | |
591 | * @offset : offset within the buffer | |
592 | * @virt : pointer to page address (output) | |
593 | * | |
594 | * Should be protected by get_subbuf/put_subbuf. | |
595 | * Returns the pointer to the page struct pointer. | |
596 | */ | |
597 | struct page **lib_ring_buffer_read_get_page(struct lib_ring_buffer_backend *bufb, | |
598 | size_t offset, void ***virt) | |
599 | { | |
600 | size_t index; | |
601 | struct lib_ring_buffer_backend_pages *rpages; | |
602 | struct channel_backend *chanb = &bufb->chan->backend; | |
603 | const struct lib_ring_buffer_config *config = chanb->config; | |
604 | unsigned long sb_bindex, id; | |
605 | ||
606 | offset &= chanb->buf_size - 1; | |
14641deb | 607 | index = (offset & (chanb->subbuf_size - 1)) >> get_count_order(PAGE_SIZE); |
852c2936 MD |
608 | id = bufb->buf_rsb.id; |
609 | sb_bindex = subbuffer_id_get_index(config, id); | |
610 | rpages = bufb->array[sb_bindex]; | |
611 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE | |
612 | && subbuffer_id_is_noref(config, id)); | |
613 | *virt = &rpages->p[index].virt; | |
614 | return &rpages->p[index].page; | |
615 | } | |
616 | EXPORT_SYMBOL_GPL(lib_ring_buffer_read_get_page); | |
617 | ||
618 | /** | |
619 | * lib_ring_buffer_read_offset_address - get address of a buffer location | |
620 | * @bufb : buffer backend | |
621 | * @offset : offset within the buffer. | |
622 | * | |
623 | * Return the address where a given offset is located (for read). | |
624 | * Should be used to get the current subbuffer header pointer. Given we know | |
625 | * it's never on a page boundary, it's safe to write directly to this address, | |
626 | * as long as the write is never bigger than a page size. | |
627 | */ | |
628 | void *lib_ring_buffer_read_offset_address(struct lib_ring_buffer_backend *bufb, | |
629 | size_t offset) | |
630 | { | |
631 | size_t index; | |
632 | struct lib_ring_buffer_backend_pages *rpages; | |
633 | struct channel_backend *chanb = &bufb->chan->backend; | |
634 | const struct lib_ring_buffer_config *config = chanb->config; | |
635 | unsigned long sb_bindex, id; | |
636 | ||
637 | offset &= chanb->buf_size - 1; | |
14641deb | 638 | index = (offset & (chanb->subbuf_size - 1)) >> get_count_order(PAGE_SIZE); |
852c2936 MD |
639 | id = bufb->buf_rsb.id; |
640 | sb_bindex = subbuffer_id_get_index(config, id); | |
641 | rpages = bufb->array[sb_bindex]; | |
642 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE | |
643 | && subbuffer_id_is_noref(config, id)); | |
644 | return rpages->p[index].virt + (offset & ~PAGE_MASK); | |
645 | } | |
646 | EXPORT_SYMBOL_GPL(lib_ring_buffer_read_offset_address); | |
647 | ||
648 | /** | |
649 | * lib_ring_buffer_offset_address - get address of a location within the buffer | |
650 | * @bufb : buffer backend | |
651 | * @offset : offset within the buffer. | |
652 | * | |
653 | * Return the address where a given offset is located. | |
654 | * Should be used to get the current subbuffer header pointer. Given we know | |
655 | * it's always at the beginning of a page, it's safe to write directly to this | |
656 | * address, as long as the write is never bigger than a page size. | |
657 | */ | |
658 | void *lib_ring_buffer_offset_address(struct lib_ring_buffer_backend *bufb, | |
659 | size_t offset) | |
660 | { | |
661 | size_t sbidx, index; | |
662 | struct lib_ring_buffer_backend_pages *rpages; | |
663 | struct channel_backend *chanb = &bufb->chan->backend; | |
664 | const struct lib_ring_buffer_config *config = chanb->config; | |
665 | unsigned long sb_bindex, id; | |
666 | ||
667 | offset &= chanb->buf_size - 1; | |
668 | sbidx = offset >> chanb->subbuf_size_order; | |
14641deb | 669 | index = (offset & (chanb->subbuf_size - 1)) >> get_count_order(PAGE_SIZE); |
852c2936 MD |
670 | id = bufb->buf_wsb[sbidx].id; |
671 | sb_bindex = subbuffer_id_get_index(config, id); | |
672 | rpages = bufb->array[sb_bindex]; | |
673 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE | |
674 | && subbuffer_id_is_noref(config, id)); | |
675 | return rpages->p[index].virt + (offset & ~PAGE_MASK); | |
676 | } | |
677 | EXPORT_SYMBOL_GPL(lib_ring_buffer_offset_address); |