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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 | ||
4931a13e MD |
9 | #include "config.h" |
10 | #include "backend.h" | |
11 | #include "frontend.h" | |
852c2936 MD |
12 | |
13 | /** | |
14 | * lib_ring_buffer_backend_allocate - allocate a channel buffer | |
15 | * @config: ring buffer instance configuration | |
16 | * @buf: the buffer struct | |
17 | * @size: total size of the buffer | |
18 | * @num_subbuf: number of subbuffers | |
19 | * @extra_reader_sb: need extra subbuffer for reader | |
20 | */ | |
21 | static | |
22 | int lib_ring_buffer_backend_allocate(const struct lib_ring_buffer_config *config, | |
23 | struct lib_ring_buffer_backend *bufb, | |
24 | size_t size, size_t num_subbuf, | |
25 | int extra_reader_sb) | |
26 | { | |
27 | struct channel_backend *chanb = &bufb->chan->backend; | |
28 | unsigned long j, num_pages, num_pages_per_subbuf, page_idx = 0; | |
29 | unsigned long subbuf_size, mmap_offset = 0; | |
30 | unsigned long num_subbuf_alloc; | |
31 | struct page **pages; | |
32 | void **virt; | |
33 | unsigned long i; | |
34 | ||
35 | num_pages = size >> PAGE_SHIFT; | |
36 | num_pages_per_subbuf = num_pages >> get_count_order(num_subbuf); | |
37 | subbuf_size = chanb->subbuf_size; | |
38 | num_subbuf_alloc = num_subbuf; | |
39 | ||
40 | if (extra_reader_sb) { | |
41 | num_pages += num_pages_per_subbuf; /* Add pages for reader */ | |
42 | num_subbuf_alloc++; | |
43 | } | |
44 | ||
45 | pages = kmalloc_node(ALIGN(sizeof(*pages) * num_pages, | |
46 | 1 << INTERNODE_CACHE_SHIFT), | |
47 | GFP_KERNEL, cpu_to_node(max(bufb->cpu, 0))); | |
48 | if (unlikely(!pages)) | |
49 | goto pages_error; | |
50 | ||
51 | virt = kmalloc_node(ALIGN(sizeof(*virt) * num_pages, | |
52 | 1 << INTERNODE_CACHE_SHIFT), | |
53 | GFP_KERNEL, cpu_to_node(max(bufb->cpu, 0))); | |
54 | if (unlikely(!virt)) | |
55 | goto virt_error; | |
56 | ||
57 | bufb->array = kmalloc_node(ALIGN(sizeof(*bufb->array) | |
58 | * num_subbuf_alloc, | |
59 | 1 << INTERNODE_CACHE_SHIFT), | |
60 | GFP_KERNEL, cpu_to_node(max(bufb->cpu, 0))); | |
61 | if (unlikely(!bufb->array)) | |
62 | goto array_error; | |
63 | ||
64 | for (i = 0; i < num_pages; i++) { | |
65 | pages[i] = alloc_pages_node(cpu_to_node(max(bufb->cpu, 0)), | |
66 | GFP_KERNEL | __GFP_ZERO, 0); | |
67 | if (unlikely(!pages[i])) | |
68 | goto depopulate; | |
69 | virt[i] = page_address(pages[i]); | |
70 | } | |
71 | bufb->num_pages_per_subbuf = num_pages_per_subbuf; | |
72 | ||
73 | /* Allocate backend pages array elements */ | |
74 | for (i = 0; i < num_subbuf_alloc; i++) { | |
75 | bufb->array[i] = | |
76 | kzalloc_node(ALIGN( | |
77 | sizeof(struct lib_ring_buffer_backend_pages) + | |
78 | sizeof(struct lib_ring_buffer_backend_page) | |
79 | * num_pages_per_subbuf, | |
80 | 1 << INTERNODE_CACHE_SHIFT), | |
81 | GFP_KERNEL, cpu_to_node(max(bufb->cpu, 0))); | |
82 | if (!bufb->array[i]) | |
83 | goto free_array; | |
84 | } | |
85 | ||
86 | /* Allocate write-side subbuffer table */ | |
87 | bufb->buf_wsb = kzalloc_node(ALIGN( | |
88 | sizeof(struct lib_ring_buffer_backend_subbuffer) | |
89 | * num_subbuf, | |
90 | 1 << INTERNODE_CACHE_SHIFT), | |
91 | GFP_KERNEL, cpu_to_node(max(bufb->cpu, 0))); | |
92 | if (unlikely(!bufb->buf_wsb)) | |
93 | goto free_array; | |
94 | ||
95 | for (i = 0; i < num_subbuf; i++) | |
96 | bufb->buf_wsb[i].id = subbuffer_id(config, 0, 1, i); | |
97 | ||
98 | /* Assign read-side subbuffer table */ | |
99 | if (extra_reader_sb) | |
100 | bufb->buf_rsb.id = subbuffer_id(config, 0, 1, | |
101 | num_subbuf_alloc - 1); | |
102 | else | |
103 | bufb->buf_rsb.id = subbuffer_id(config, 0, 1, 0); | |
104 | ||
105 | /* Assign pages to page index */ | |
106 | for (i = 0; i < num_subbuf_alloc; i++) { | |
107 | for (j = 0; j < num_pages_per_subbuf; j++) { | |
108 | CHAN_WARN_ON(chanb, page_idx > num_pages); | |
109 | bufb->array[i]->p[j].virt = virt[page_idx]; | |
110 | bufb->array[i]->p[j].page = pages[page_idx]; | |
111 | page_idx++; | |
112 | } | |
113 | if (config->output == RING_BUFFER_MMAP) { | |
114 | bufb->array[i]->mmap_offset = mmap_offset; | |
115 | mmap_offset += subbuf_size; | |
116 | } | |
117 | } | |
118 | ||
119 | /* | |
120 | * If kmalloc ever uses vmalloc underneath, make sure the buffer pages | |
121 | * will not fault. | |
122 | */ | |
123 | wrapper_vmalloc_sync_all(); | |
124 | kfree(virt); | |
125 | kfree(pages); | |
126 | return 0; | |
127 | ||
128 | free_array: | |
129 | for (i = 0; (i < num_subbuf_alloc && bufb->array[i]); i++) | |
130 | kfree(bufb->array[i]); | |
131 | depopulate: | |
132 | /* Free all allocated pages */ | |
133 | for (i = 0; (i < num_pages && pages[i]); i++) | |
134 | __free_page(pages[i]); | |
135 | kfree(bufb->array); | |
136 | array_error: | |
137 | kfree(virt); | |
138 | virt_error: | |
139 | kfree(pages); | |
140 | pages_error: | |
141 | return -ENOMEM; | |
142 | } | |
143 | ||
144 | int lib_ring_buffer_backend_create(struct lib_ring_buffer_backend *bufb, | |
145 | struct channel_backend *chanb, int cpu) | |
146 | { | |
147 | const struct lib_ring_buffer_config *config = chanb->config; | |
148 | ||
149 | bufb->chan = container_of(chanb, struct channel, backend); | |
150 | bufb->cpu = cpu; | |
151 | ||
152 | return lib_ring_buffer_backend_allocate(config, bufb, chanb->buf_size, | |
153 | chanb->num_subbuf, | |
154 | chanb->extra_reader_sb); | |
155 | } | |
156 | ||
157 | void lib_ring_buffer_backend_free(struct lib_ring_buffer_backend *bufb) | |
158 | { | |
159 | struct channel_backend *chanb = &bufb->chan->backend; | |
160 | unsigned long i, j, num_subbuf_alloc; | |
161 | ||
162 | num_subbuf_alloc = chanb->num_subbuf; | |
163 | if (chanb->extra_reader_sb) | |
164 | num_subbuf_alloc++; | |
165 | ||
166 | kfree(bufb->buf_wsb); | |
167 | for (i = 0; i < num_subbuf_alloc; i++) { | |
168 | for (j = 0; j < bufb->num_pages_per_subbuf; j++) | |
169 | __free_page(bufb->array[i]->p[j].page); | |
170 | kfree(bufb->array[i]); | |
171 | } | |
172 | kfree(bufb->array); | |
173 | bufb->allocated = 0; | |
174 | } | |
175 | ||
176 | void lib_ring_buffer_backend_reset(struct lib_ring_buffer_backend *bufb) | |
177 | { | |
178 | struct channel_backend *chanb = &bufb->chan->backend; | |
179 | const struct lib_ring_buffer_config *config = chanb->config; | |
180 | unsigned long num_subbuf_alloc; | |
181 | unsigned int i; | |
182 | ||
183 | num_subbuf_alloc = chanb->num_subbuf; | |
184 | if (chanb->extra_reader_sb) | |
185 | num_subbuf_alloc++; | |
186 | ||
187 | for (i = 0; i < chanb->num_subbuf; i++) | |
188 | bufb->buf_wsb[i].id = subbuffer_id(config, 0, 1, i); | |
189 | if (chanb->extra_reader_sb) | |
190 | bufb->buf_rsb.id = subbuffer_id(config, 0, 1, | |
191 | num_subbuf_alloc - 1); | |
192 | else | |
193 | bufb->buf_rsb.id = subbuffer_id(config, 0, 1, 0); | |
194 | ||
195 | for (i = 0; i < num_subbuf_alloc; i++) { | |
196 | /* Don't reset mmap_offset */ | |
197 | v_set(config, &bufb->array[i]->records_commit, 0); | |
198 | v_set(config, &bufb->array[i]->records_unread, 0); | |
199 | bufb->array[i]->data_size = 0; | |
200 | /* Don't reset backend page and virt addresses */ | |
201 | } | |
202 | /* Don't reset num_pages_per_subbuf, cpu, allocated */ | |
203 | v_set(config, &bufb->records_read, 0); | |
204 | } | |
205 | ||
206 | /* | |
207 | * The frontend is responsible for also calling ring_buffer_backend_reset for | |
208 | * each buffer when calling channel_backend_reset. | |
209 | */ | |
210 | void channel_backend_reset(struct channel_backend *chanb) | |
211 | { | |
212 | struct channel *chan = container_of(chanb, struct channel, backend); | |
213 | const struct lib_ring_buffer_config *config = chanb->config; | |
214 | ||
215 | /* | |
216 | * Don't reset buf_size, subbuf_size, subbuf_size_order, | |
217 | * num_subbuf_order, buf_size_order, extra_reader_sb, num_subbuf, | |
218 | * priv, notifiers, config, cpumask and name. | |
219 | */ | |
220 | chanb->start_tsc = config->cb.ring_buffer_clock_read(chan); | |
221 | } | |
222 | ||
223 | #ifdef CONFIG_HOTPLUG_CPU | |
224 | /** | |
225 | * lib_ring_buffer_cpu_hp_callback - CPU hotplug callback | |
226 | * @nb: notifier block | |
227 | * @action: hotplug action to take | |
228 | * @hcpu: CPU number | |
229 | * | |
230 | * Returns the success/failure of the operation. (%NOTIFY_OK, %NOTIFY_BAD) | |
231 | */ | |
232 | static | |
233 | int __cpuinit lib_ring_buffer_cpu_hp_callback(struct notifier_block *nb, | |
234 | unsigned long action, | |
235 | void *hcpu) | |
236 | { | |
237 | unsigned int cpu = (unsigned long)hcpu; | |
238 | struct channel_backend *chanb = container_of(nb, struct channel_backend, | |
239 | cpu_hp_notifier); | |
240 | const struct lib_ring_buffer_config *config = chanb->config; | |
241 | struct lib_ring_buffer *buf; | |
242 | int ret; | |
243 | ||
244 | CHAN_WARN_ON(chanb, config->alloc == RING_BUFFER_ALLOC_GLOBAL); | |
245 | ||
246 | switch (action) { | |
247 | case CPU_UP_PREPARE: | |
248 | case CPU_UP_PREPARE_FROZEN: | |
249 | buf = per_cpu_ptr(chanb->buf, cpu); | |
250 | ret = lib_ring_buffer_create(buf, chanb, cpu); | |
251 | if (ret) { | |
252 | printk(KERN_ERR | |
253 | "ring_buffer_cpu_hp_callback: cpu %d " | |
254 | "buffer creation failed\n", cpu); | |
255 | return NOTIFY_BAD; | |
256 | } | |
257 | break; | |
258 | case CPU_DEAD: | |
259 | case CPU_DEAD_FROZEN: | |
260 | /* No need to do a buffer switch here, because it will happen | |
261 | * when tracing is stopped, or will be done by switch timer CPU | |
262 | * DEAD callback. */ | |
263 | break; | |
264 | } | |
265 | return NOTIFY_OK; | |
266 | } | |
267 | #endif | |
268 | ||
269 | /** | |
270 | * channel_backend_init - initialize a channel backend | |
271 | * @chanb: channel backend | |
272 | * @name: channel name | |
273 | * @config: client ring buffer configuration | |
274 | * @priv: client private data | |
275 | * @parent: dentry of parent directory, %NULL for root directory | |
276 | * @subbuf_size: size of sub-buffers (> PAGE_SIZE, power of 2) | |
277 | * @num_subbuf: number of sub-buffers (power of 2) | |
278 | * | |
279 | * Returns channel pointer if successful, %NULL otherwise. | |
280 | * | |
281 | * Creates per-cpu channel buffers using the sizes and attributes | |
282 | * specified. The created channel buffer files will be named | |
283 | * name_0...name_N-1. File permissions will be %S_IRUSR. | |
284 | * | |
285 | * Called with CPU hotplug disabled. | |
286 | */ | |
287 | int channel_backend_init(struct channel_backend *chanb, | |
288 | const char *name, | |
289 | const struct lib_ring_buffer_config *config, | |
290 | void *priv, size_t subbuf_size, size_t num_subbuf) | |
291 | { | |
292 | struct channel *chan = container_of(chanb, struct channel, backend); | |
293 | unsigned int i; | |
294 | int ret; | |
295 | ||
296 | if (!name) | |
297 | return -EPERM; | |
298 | ||
299 | if (!(subbuf_size && num_subbuf)) | |
300 | return -EPERM; | |
301 | ||
302 | /* Check that the subbuffer size is larger than a page. */ | |
303 | if (subbuf_size < PAGE_SIZE) | |
304 | return -EINVAL; | |
305 | ||
306 | /* | |
307 | * Make sure the number of subbuffers and subbuffer size are power of 2. | |
308 | */ | |
309 | CHAN_WARN_ON(chanb, hweight32(subbuf_size) != 1); | |
310 | CHAN_WARN_ON(chanb, hweight32(num_subbuf) != 1); | |
311 | ||
312 | ret = subbuffer_id_check_index(config, num_subbuf); | |
313 | if (ret) | |
314 | return ret; | |
315 | ||
316 | chanb->priv = priv; | |
317 | chanb->buf_size = num_subbuf * subbuf_size; | |
318 | chanb->subbuf_size = subbuf_size; | |
319 | chanb->buf_size_order = get_count_order(chanb->buf_size); | |
320 | chanb->subbuf_size_order = get_count_order(subbuf_size); | |
321 | chanb->num_subbuf_order = get_count_order(num_subbuf); | |
322 | chanb->extra_reader_sb = | |
323 | (config->mode == RING_BUFFER_OVERWRITE) ? 1 : 0; | |
324 | chanb->num_subbuf = num_subbuf; | |
325 | strlcpy(chanb->name, name, NAME_MAX); | |
326 | chanb->config = config; | |
327 | ||
328 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) { | |
329 | if (!zalloc_cpumask_var(&chanb->cpumask, GFP_KERNEL)) | |
330 | return -ENOMEM; | |
331 | } | |
332 | ||
333 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) { | |
334 | /* Allocating the buffer per-cpu structures */ | |
335 | chanb->buf = alloc_percpu(struct lib_ring_buffer); | |
336 | if (!chanb->buf) | |
337 | goto free_cpumask; | |
338 | ||
339 | /* | |
340 | * In case of non-hotplug cpu, if the ring-buffer is allocated | |
341 | * in early initcall, it will not be notified of secondary cpus. | |
342 | * In that off case, we need to allocate for all possible cpus. | |
343 | */ | |
344 | #ifdef CONFIG_HOTPLUG_CPU | |
345 | /* | |
346 | * buf->backend.allocated test takes care of concurrent CPU | |
347 | * hotplug. | |
348 | * Priority higher than frontend, so we create the ring buffer | |
349 | * before we start the timer. | |
350 | */ | |
351 | chanb->cpu_hp_notifier.notifier_call = | |
352 | lib_ring_buffer_cpu_hp_callback; | |
353 | chanb->cpu_hp_notifier.priority = 5; | |
354 | register_hotcpu_notifier(&chanb->cpu_hp_notifier); | |
355 | ||
356 | get_online_cpus(); | |
357 | for_each_online_cpu(i) { | |
358 | ret = lib_ring_buffer_create(per_cpu_ptr(chanb->buf, i), | |
359 | chanb, i); | |
360 | if (ret) | |
361 | goto free_bufs; /* cpu hotplug locked */ | |
362 | } | |
363 | put_online_cpus(); | |
364 | #else | |
365 | for_each_possible_cpu(i) { | |
366 | ret = lib_ring_buffer_create(per_cpu_ptr(chanb->buf, i), | |
367 | chanb, i); | |
368 | if (ret) | |
369 | goto free_bufs; /* cpu hotplug locked */ | |
370 | } | |
371 | #endif | |
372 | } else { | |
373 | chanb->buf = kzalloc(sizeof(struct lib_ring_buffer), GFP_KERNEL); | |
374 | if (!chanb->buf) | |
375 | goto free_cpumask; | |
376 | ret = lib_ring_buffer_create(chanb->buf, chanb, -1); | |
377 | if (ret) | |
378 | goto free_bufs; | |
379 | } | |
380 | chanb->start_tsc = config->cb.ring_buffer_clock_read(chan); | |
381 | ||
382 | return 0; | |
383 | ||
384 | free_bufs: | |
385 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) { | |
386 | for_each_possible_cpu(i) { | |
387 | struct lib_ring_buffer *buf = per_cpu_ptr(chanb->buf, i); | |
388 | ||
389 | if (!buf->backend.allocated) | |
390 | continue; | |
391 | lib_ring_buffer_free(buf); | |
392 | } | |
393 | #ifdef CONFIG_HOTPLUG_CPU | |
394 | put_online_cpus(); | |
395 | #endif | |
396 | free_percpu(chanb->buf); | |
397 | } else | |
398 | kfree(chanb->buf); | |
399 | free_cpumask: | |
400 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) | |
401 | free_cpumask_var(chanb->cpumask); | |
402 | return -ENOMEM; | |
403 | } | |
404 | ||
405 | /** | |
406 | * channel_backend_unregister_notifiers - unregister notifiers | |
407 | * @chan: the channel | |
408 | * | |
409 | * Holds CPU hotplug. | |
410 | */ | |
411 | void channel_backend_unregister_notifiers(struct channel_backend *chanb) | |
412 | { | |
413 | const struct lib_ring_buffer_config *config = chanb->config; | |
414 | ||
415 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) | |
416 | unregister_hotcpu_notifier(&chanb->cpu_hp_notifier); | |
417 | } | |
418 | ||
419 | /** | |
420 | * channel_backend_free - destroy the channel | |
421 | * @chan: the channel | |
422 | * | |
423 | * Destroy all channel buffers and frees the channel. | |
424 | */ | |
425 | void channel_backend_free(struct channel_backend *chanb) | |
426 | { | |
427 | const struct lib_ring_buffer_config *config = chanb->config; | |
428 | unsigned int i; | |
429 | ||
430 | if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) { | |
431 | for_each_possible_cpu(i) { | |
432 | struct lib_ring_buffer *buf = per_cpu_ptr(chanb->buf, i); | |
433 | ||
434 | if (!buf->backend.allocated) | |
435 | continue; | |
436 | lib_ring_buffer_free(buf); | |
437 | } | |
438 | free_cpumask_var(chanb->cpumask); | |
439 | free_percpu(chanb->buf); | |
440 | } else { | |
441 | struct lib_ring_buffer *buf = chanb->buf; | |
442 | ||
443 | CHAN_WARN_ON(chanb, !buf->backend.allocated); | |
444 | lib_ring_buffer_free(buf); | |
445 | kfree(buf); | |
446 | } | |
447 | } | |
448 | ||
449 | /** | |
450 | * lib_ring_buffer_write - write data to a ring_buffer buffer. | |
451 | * @bufb : buffer backend | |
452 | * @offset : offset within the buffer | |
453 | * @src : source address | |
454 | * @len : length to write | |
455 | * @pagecpy : page size copied so far | |
456 | */ | |
457 | void _lib_ring_buffer_write(struct lib_ring_buffer_backend *bufb, size_t offset, | |
458 | const void *src, size_t len, ssize_t pagecpy) | |
459 | { | |
460 | struct channel_backend *chanb = &bufb->chan->backend; | |
461 | const struct lib_ring_buffer_config *config = chanb->config; | |
462 | size_t sbidx, index; | |
463 | struct lib_ring_buffer_backend_pages *rpages; | |
464 | unsigned long sb_bindex, id; | |
465 | ||
466 | do { | |
467 | len -= pagecpy; | |
468 | src += pagecpy; | |
469 | offset += pagecpy; | |
470 | sbidx = offset >> chanb->subbuf_size_order; | |
471 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; | |
472 | ||
473 | /* | |
474 | * Underlying layer should never ask for writes across | |
475 | * subbuffers. | |
476 | */ | |
477 | CHAN_WARN_ON(chanb, offset >= chanb->buf_size); | |
478 | ||
479 | pagecpy = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK)); | |
480 | id = bufb->buf_wsb[sbidx].id; | |
481 | sb_bindex = subbuffer_id_get_index(config, id); | |
482 | rpages = bufb->array[sb_bindex]; | |
483 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE | |
484 | && subbuffer_id_is_noref(config, id)); | |
485 | lib_ring_buffer_do_copy(config, | |
486 | rpages->p[index].virt | |
487 | + (offset & ~PAGE_MASK), | |
488 | src, pagecpy); | |
489 | } while (unlikely(len != pagecpy)); | |
490 | } | |
491 | EXPORT_SYMBOL_GPL(_lib_ring_buffer_write); | |
492 | ||
493 | /** | |
494 | * lib_ring_buffer_read - read data from ring_buffer_buffer. | |
495 | * @bufb : buffer backend | |
496 | * @offset : offset within the buffer | |
497 | * @dest : destination address | |
498 | * @len : length to copy to destination | |
499 | * | |
500 | * Should be protected by get_subbuf/put_subbuf. | |
501 | * Returns the length copied. | |
502 | */ | |
503 | size_t lib_ring_buffer_read(struct lib_ring_buffer_backend *bufb, size_t offset, | |
504 | void *dest, size_t len) | |
505 | { | |
506 | struct channel_backend *chanb = &bufb->chan->backend; | |
507 | const struct lib_ring_buffer_config *config = chanb->config; | |
508 | size_t index; | |
509 | ssize_t pagecpy, orig_len; | |
510 | struct lib_ring_buffer_backend_pages *rpages; | |
511 | unsigned long sb_bindex, id; | |
512 | ||
513 | orig_len = len; | |
514 | offset &= chanb->buf_size - 1; | |
515 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; | |
516 | if (unlikely(!len)) | |
517 | return 0; | |
518 | for (;;) { | |
519 | pagecpy = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK)); | |
520 | id = bufb->buf_rsb.id; | |
521 | sb_bindex = subbuffer_id_get_index(config, id); | |
522 | rpages = bufb->array[sb_bindex]; | |
523 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE | |
524 | && subbuffer_id_is_noref(config, id)); | |
525 | memcpy(dest, rpages->p[index].virt + (offset & ~PAGE_MASK), | |
526 | pagecpy); | |
527 | len -= pagecpy; | |
528 | if (likely(!len)) | |
529 | break; | |
530 | dest += pagecpy; | |
531 | offset += pagecpy; | |
532 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; | |
533 | /* | |
534 | * Underlying layer should never ask for reads across | |
535 | * subbuffers. | |
536 | */ | |
537 | CHAN_WARN_ON(chanb, offset >= chanb->buf_size); | |
538 | } | |
539 | return orig_len; | |
540 | } | |
541 | EXPORT_SYMBOL_GPL(lib_ring_buffer_read); | |
542 | ||
543 | /** | |
544 | * __lib_ring_buffer_copy_to_user - read data from ring_buffer to userspace | |
545 | * @bufb : buffer backend | |
546 | * @offset : offset within the buffer | |
547 | * @dest : destination userspace address | |
548 | * @len : length to copy to destination | |
549 | * | |
550 | * Should be protected by get_subbuf/put_subbuf. | |
551 | * access_ok() must have been performed on dest addresses prior to call this | |
552 | * function. | |
553 | * Returns -EFAULT on error, 0 if ok. | |
554 | */ | |
555 | int __lib_ring_buffer_copy_to_user(struct lib_ring_buffer_backend *bufb, | |
556 | size_t offset, void __user *dest, size_t len) | |
557 | { | |
558 | struct channel_backend *chanb = &bufb->chan->backend; | |
559 | const struct lib_ring_buffer_config *config = chanb->config; | |
560 | size_t index; | |
561 | ssize_t pagecpy, orig_len; | |
562 | struct lib_ring_buffer_backend_pages *rpages; | |
563 | unsigned long sb_bindex, id; | |
564 | ||
565 | orig_len = len; | |
566 | offset &= chanb->buf_size - 1; | |
567 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; | |
568 | if (unlikely(!len)) | |
569 | return 0; | |
570 | for (;;) { | |
571 | pagecpy = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK)); | |
572 | id = bufb->buf_rsb.id; | |
573 | sb_bindex = subbuffer_id_get_index(config, id); | |
574 | rpages = bufb->array[sb_bindex]; | |
575 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE | |
576 | && subbuffer_id_is_noref(config, id)); | |
577 | if (__copy_to_user(dest, | |
578 | rpages->p[index].virt + (offset & ~PAGE_MASK), | |
579 | pagecpy)) | |
580 | return -EFAULT; | |
581 | len -= pagecpy; | |
582 | if (likely(!len)) | |
583 | break; | |
584 | dest += pagecpy; | |
585 | offset += pagecpy; | |
586 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; | |
587 | /* | |
588 | * Underlying layer should never ask for reads across | |
589 | * subbuffers. | |
590 | */ | |
591 | CHAN_WARN_ON(chanb, offset >= chanb->buf_size); | |
592 | } | |
593 | return 0; | |
594 | } | |
595 | EXPORT_SYMBOL_GPL(__lib_ring_buffer_copy_to_user); | |
596 | ||
597 | /** | |
598 | * lib_ring_buffer_read_cstr - read a C-style string from ring_buffer. | |
599 | * @bufb : buffer backend | |
600 | * @offset : offset within the buffer | |
601 | * @dest : destination address | |
602 | * @len : destination's length | |
603 | * | |
604 | * return string's length | |
605 | * Should be protected by get_subbuf/put_subbuf. | |
606 | */ | |
607 | int lib_ring_buffer_read_cstr(struct lib_ring_buffer_backend *bufb, size_t offset, | |
608 | void *dest, size_t len) | |
609 | { | |
610 | struct channel_backend *chanb = &bufb->chan->backend; | |
611 | const struct lib_ring_buffer_config *config = chanb->config; | |
612 | size_t index; | |
613 | ssize_t pagecpy, pagelen, strpagelen, orig_offset; | |
614 | char *str; | |
615 | struct lib_ring_buffer_backend_pages *rpages; | |
616 | unsigned long sb_bindex, id; | |
617 | ||
618 | offset &= chanb->buf_size - 1; | |
619 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; | |
620 | orig_offset = offset; | |
621 | for (;;) { | |
622 | id = bufb->buf_rsb.id; | |
623 | sb_bindex = subbuffer_id_get_index(config, id); | |
624 | rpages = bufb->array[sb_bindex]; | |
625 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE | |
626 | && subbuffer_id_is_noref(config, id)); | |
627 | str = (char *)rpages->p[index].virt + (offset & ~PAGE_MASK); | |
628 | pagelen = PAGE_SIZE - (offset & ~PAGE_MASK); | |
629 | strpagelen = strnlen(str, pagelen); | |
630 | if (len) { | |
631 | pagecpy = min_t(size_t, len, strpagelen); | |
632 | if (dest) { | |
633 | memcpy(dest, str, pagecpy); | |
634 | dest += pagecpy; | |
635 | } | |
636 | len -= pagecpy; | |
637 | } | |
638 | offset += strpagelen; | |
639 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; | |
640 | if (strpagelen < pagelen) | |
641 | break; | |
642 | /* | |
643 | * Underlying layer should never ask for reads across | |
644 | * subbuffers. | |
645 | */ | |
646 | CHAN_WARN_ON(chanb, offset >= chanb->buf_size); | |
647 | } | |
648 | if (dest && len) | |
649 | ((char *)dest)[0] = 0; | |
650 | return offset - orig_offset; | |
651 | } | |
652 | EXPORT_SYMBOL_GPL(lib_ring_buffer_read_cstr); | |
653 | ||
654 | /** | |
655 | * lib_ring_buffer_read_get_page - Get a whole page to read from | |
656 | * @bufb : buffer backend | |
657 | * @offset : offset within the buffer | |
658 | * @virt : pointer to page address (output) | |
659 | * | |
660 | * Should be protected by get_subbuf/put_subbuf. | |
661 | * Returns the pointer to the page struct pointer. | |
662 | */ | |
663 | struct page **lib_ring_buffer_read_get_page(struct lib_ring_buffer_backend *bufb, | |
664 | size_t offset, void ***virt) | |
665 | { | |
666 | size_t index; | |
667 | struct lib_ring_buffer_backend_pages *rpages; | |
668 | struct channel_backend *chanb = &bufb->chan->backend; | |
669 | const struct lib_ring_buffer_config *config = chanb->config; | |
670 | unsigned long sb_bindex, id; | |
671 | ||
672 | offset &= chanb->buf_size - 1; | |
673 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; | |
674 | id = bufb->buf_rsb.id; | |
675 | sb_bindex = subbuffer_id_get_index(config, id); | |
676 | rpages = bufb->array[sb_bindex]; | |
677 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE | |
678 | && subbuffer_id_is_noref(config, id)); | |
679 | *virt = &rpages->p[index].virt; | |
680 | return &rpages->p[index].page; | |
681 | } | |
682 | EXPORT_SYMBOL_GPL(lib_ring_buffer_read_get_page); | |
683 | ||
684 | /** | |
685 | * lib_ring_buffer_read_offset_address - get address of a buffer location | |
686 | * @bufb : buffer backend | |
687 | * @offset : offset within the buffer. | |
688 | * | |
689 | * Return the address where a given offset is located (for read). | |
690 | * Should be used to get the current subbuffer header pointer. Given we know | |
691 | * it's never on a page boundary, it's safe to write directly to this address, | |
692 | * as long as the write is never bigger than a page size. | |
693 | */ | |
694 | void *lib_ring_buffer_read_offset_address(struct lib_ring_buffer_backend *bufb, | |
695 | size_t offset) | |
696 | { | |
697 | size_t index; | |
698 | struct lib_ring_buffer_backend_pages *rpages; | |
699 | struct channel_backend *chanb = &bufb->chan->backend; | |
700 | const struct lib_ring_buffer_config *config = chanb->config; | |
701 | unsigned long sb_bindex, id; | |
702 | ||
703 | offset &= chanb->buf_size - 1; | |
704 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; | |
705 | id = bufb->buf_rsb.id; | |
706 | sb_bindex = subbuffer_id_get_index(config, id); | |
707 | rpages = bufb->array[sb_bindex]; | |
708 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE | |
709 | && subbuffer_id_is_noref(config, id)); | |
710 | return rpages->p[index].virt + (offset & ~PAGE_MASK); | |
711 | } | |
712 | EXPORT_SYMBOL_GPL(lib_ring_buffer_read_offset_address); | |
713 | ||
714 | /** | |
715 | * lib_ring_buffer_offset_address - get address of a location within the buffer | |
716 | * @bufb : buffer backend | |
717 | * @offset : offset within the buffer. | |
718 | * | |
719 | * Return the address where a given offset is located. | |
720 | * Should be used to get the current subbuffer header pointer. Given we know | |
721 | * it's always at the beginning of a page, it's safe to write directly to this | |
722 | * address, as long as the write is never bigger than a page size. | |
723 | */ | |
724 | void *lib_ring_buffer_offset_address(struct lib_ring_buffer_backend *bufb, | |
725 | size_t offset) | |
726 | { | |
727 | size_t sbidx, index; | |
728 | struct lib_ring_buffer_backend_pages *rpages; | |
729 | struct channel_backend *chanb = &bufb->chan->backend; | |
730 | const struct lib_ring_buffer_config *config = chanb->config; | |
731 | unsigned long sb_bindex, id; | |
732 | ||
733 | offset &= chanb->buf_size - 1; | |
734 | sbidx = offset >> chanb->subbuf_size_order; | |
735 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; | |
736 | id = bufb->buf_wsb[sbidx].id; | |
737 | sb_bindex = subbuffer_id_get_index(config, id); | |
738 | rpages = bufb->array[sb_bindex]; | |
739 | CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE | |
740 | && subbuffer_id_is_noref(config, id)); | |
741 | return rpages->p[index].virt + (offset & ~PAGE_MASK); | |
742 | } | |
743 | EXPORT_SYMBOL_GPL(lib_ring_buffer_offset_address); |