Commit | Line | Data |
---|---|---|
e1152c37 PMF |
1 | /* |
2 | * Public API and common code for kernel->userspace relay file support. | |
3 | * | |
4 | * Copyright (C) 2002-2005 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp | |
5 | * Copyright (C) 1999-2005 - Karim Yaghmour (karim@opersys.com) | |
6 | * Copyright (C) 2008 - Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca) | |
7 | * | |
8 | * Moved to kernel/relay.c by Paul Mundt, 2006. | |
9 | * November 2006 - CPU hotplug support by Mathieu Desnoyers | |
10 | * (mathieu.desnoyers@polymtl.ca) | |
11 | * | |
12 | * This file is released under the GPL. | |
13 | */ | |
14 | #include <linux/errno.h> | |
15 | #include <linux/stddef.h> | |
16 | #include <linux/slab.h> | |
17 | #include <linux/module.h> | |
18 | #include <linux/string.h> | |
19 | #include <linux/ltt-relay.h> | |
20 | #include <linux/vmalloc.h> | |
21 | #include <linux/mm.h> | |
22 | #include <linux/cpu.h> | |
23 | #include <linux/splice.h> | |
24 | #include <linux/bitops.h> | |
25 | ||
26 | /* list of open channels, for cpu hotplug */ | |
27 | static DEFINE_MUTEX(relay_channels_mutex); | |
28 | static LIST_HEAD(relay_channels); | |
29 | ||
30 | /** | |
31 | * relay_alloc_buf - allocate a channel buffer | |
32 | * @buf: the buffer struct | |
33 | * @size: total size of the buffer | |
34 | */ | |
35 | static int relay_alloc_buf(struct rchan_buf *buf, size_t *size) | |
36 | { | |
37 | unsigned int i, n_pages; | |
38 | struct buf_page *buf_page, *n; | |
39 | ||
40 | *size = PAGE_ALIGN(*size); | |
41 | n_pages = *size >> PAGE_SHIFT; | |
42 | ||
43 | INIT_LIST_HEAD(&buf->pages); | |
44 | ||
45 | for (i = 0; i < n_pages; i++) { | |
46 | buf_page = kmalloc_node(sizeof(*buf_page), GFP_KERNEL, | |
47 | cpu_to_node(buf->cpu)); | |
48 | if (unlikely(!buf_page)) | |
49 | goto depopulate; | |
50 | buf_page->page = alloc_pages_node(cpu_to_node(buf->cpu), | |
51 | GFP_KERNEL | __GFP_ZERO, 0); | |
52 | if (unlikely(!buf_page->page)) { | |
53 | kfree(buf_page); | |
54 | goto depopulate; | |
55 | } | |
56 | list_add_tail(&buf_page->list, &buf->pages); | |
57 | buf_page->offset = (size_t)i << PAGE_SHIFT; | |
58 | buf_page->buf = buf; | |
59 | set_page_private(buf_page->page, (unsigned long)buf_page); | |
60 | if (i == 0) { | |
61 | buf->wpage = buf_page; | |
62 | buf->hpage[0] = buf_page; | |
63 | buf->hpage[1] = buf_page; | |
64 | buf->rpage = buf_page; | |
65 | } | |
66 | } | |
67 | buf->page_count = n_pages; | |
68 | return 0; | |
69 | ||
70 | depopulate: | |
71 | list_for_each_entry_safe(buf_page, n, &buf->pages, list) { | |
72 | list_del_init(&buf_page->list); | |
73 | __free_page(buf_page->page); | |
74 | kfree(buf_page); | |
75 | } | |
76 | return -ENOMEM; | |
77 | } | |
78 | ||
79 | /** | |
80 | * relay_create_buf - allocate and initialize a channel buffer | |
81 | * @chan: the relay channel | |
82 | * @cpu: cpu the buffer belongs to | |
83 | * | |
84 | * Returns channel buffer if successful, %NULL otherwise. | |
85 | */ | |
86 | static struct rchan_buf *relay_create_buf(struct rchan *chan, int cpu) | |
87 | { | |
88 | int ret; | |
89 | struct rchan_buf *buf = kzalloc(sizeof(struct rchan_buf), GFP_KERNEL); | |
90 | if (!buf) | |
91 | return NULL; | |
92 | ||
93 | buf->cpu = cpu; | |
94 | ret = relay_alloc_buf(buf, &chan->alloc_size); | |
95 | if (ret) | |
96 | goto free_buf; | |
97 | ||
98 | buf->chan = chan; | |
99 | kref_get(&buf->chan->kref); | |
100 | return buf; | |
101 | ||
102 | free_buf: | |
103 | kfree(buf); | |
104 | return NULL; | |
105 | } | |
106 | ||
107 | /** | |
108 | * relay_destroy_channel - free the channel struct | |
109 | * @kref: target kernel reference that contains the relay channel | |
110 | * | |
111 | * Should only be called from kref_put(). | |
112 | */ | |
113 | static void relay_destroy_channel(struct kref *kref) | |
114 | { | |
115 | struct rchan *chan = container_of(kref, struct rchan, kref); | |
116 | kfree(chan); | |
117 | } | |
118 | ||
119 | /** | |
120 | * relay_destroy_buf - destroy an rchan_buf struct and associated buffer | |
121 | * @buf: the buffer struct | |
122 | */ | |
123 | static void relay_destroy_buf(struct rchan_buf *buf) | |
124 | { | |
125 | struct rchan *chan = buf->chan; | |
126 | struct buf_page *buf_page, *n; | |
127 | ||
128 | list_for_each_entry_safe(buf_page, n, &buf->pages, list) { | |
129 | list_del_init(&buf_page->list); | |
130 | __free_page(buf_page->page); | |
131 | kfree(buf_page); | |
132 | } | |
133 | chan->buf[buf->cpu] = NULL; | |
134 | kfree(buf); | |
135 | kref_put(&chan->kref, relay_destroy_channel); | |
136 | } | |
137 | ||
138 | /** | |
139 | * relay_remove_buf - remove a channel buffer | |
140 | * @kref: target kernel reference that contains the relay buffer | |
141 | * | |
142 | * Removes the file from the fileystem, which also frees the | |
143 | * rchan_buf_struct and the channel buffer. Should only be called from | |
144 | * kref_put(). | |
145 | */ | |
146 | static void relay_remove_buf(struct kref *kref) | |
147 | { | |
148 | struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref); | |
149 | buf->chan->cb->remove_buf_file(buf->dentry); | |
150 | relay_destroy_buf(buf); | |
151 | } | |
152 | ||
153 | /* | |
154 | * High-level relay kernel API and associated functions. | |
155 | */ | |
156 | ||
157 | /* | |
158 | * rchan_callback implementations defining default channel behavior. Used | |
159 | * in place of corresponding NULL values in client callback struct. | |
160 | */ | |
161 | ||
162 | /* | |
163 | * create_buf_file_create() default callback. Does nothing. | |
164 | */ | |
165 | static struct dentry *create_buf_file_default_callback(const char *filename, | |
166 | struct dentry *parent, | |
167 | int mode, | |
168 | struct rchan_buf *buf) | |
169 | { | |
170 | return NULL; | |
171 | } | |
172 | ||
173 | /* | |
174 | * remove_buf_file() default callback. Does nothing. | |
175 | */ | |
176 | static int remove_buf_file_default_callback(struct dentry *dentry) | |
177 | { | |
178 | return -EINVAL; | |
179 | } | |
180 | ||
181 | /* relay channel default callbacks */ | |
182 | static struct rchan_callbacks default_channel_callbacks = { | |
183 | .create_buf_file = create_buf_file_default_callback, | |
184 | .remove_buf_file = remove_buf_file_default_callback, | |
185 | }; | |
186 | ||
187 | /** | |
188 | * wakeup_readers - wake up readers waiting on a channel | |
189 | * @data: contains the channel buffer | |
190 | * | |
191 | * This is the timer function used to defer reader waking. | |
192 | */ | |
193 | static void wakeup_readers(unsigned long data) | |
194 | { | |
195 | struct rchan_buf *buf = (struct rchan_buf *)data; | |
196 | wake_up_interruptible(&buf->read_wait); | |
197 | } | |
198 | ||
199 | /** | |
200 | * __relay_reset - reset a channel buffer | |
201 | * @buf: the channel buffer | |
202 | * @init: 1 if this is a first-time initialization | |
203 | * | |
204 | * See relay_reset() for description of effect. | |
205 | */ | |
206 | static void __relay_reset(struct rchan_buf *buf, unsigned int init) | |
207 | { | |
208 | if (init) { | |
209 | init_waitqueue_head(&buf->read_wait); | |
210 | kref_init(&buf->kref); | |
211 | setup_timer(&buf->timer, wakeup_readers, (unsigned long)buf); | |
212 | } else | |
213 | del_timer_sync(&buf->timer); | |
214 | ||
215 | buf->finalized = 0; | |
216 | } | |
217 | ||
218 | /* | |
219 | * relay_open_buf - create a new relay channel buffer | |
220 | * | |
221 | * used by relay_open() and CPU hotplug. | |
222 | */ | |
223 | static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu) | |
224 | { | |
225 | struct rchan_buf *buf = NULL; | |
226 | struct dentry *dentry; | |
227 | char *tmpname; | |
228 | ||
229 | tmpname = kzalloc(NAME_MAX + 1, GFP_KERNEL); | |
230 | if (!tmpname) | |
231 | goto end; | |
232 | snprintf(tmpname, NAME_MAX, "%s%d", chan->base_filename, cpu); | |
233 | ||
234 | buf = relay_create_buf(chan, cpu); | |
235 | if (!buf) | |
236 | goto free_name; | |
237 | ||
238 | __relay_reset(buf, 1); | |
239 | ||
240 | /* Create file in fs */ | |
241 | dentry = chan->cb->create_buf_file(tmpname, chan->parent, S_IRUSR, | |
242 | buf); | |
243 | if (!dentry) | |
244 | goto free_buf; | |
245 | ||
246 | buf->dentry = dentry; | |
247 | ||
248 | goto free_name; | |
249 | ||
250 | free_buf: | |
251 | relay_destroy_buf(buf); | |
252 | buf = NULL; | |
253 | free_name: | |
254 | kfree(tmpname); | |
255 | end: | |
256 | return buf; | |
257 | } | |
258 | ||
259 | /** | |
260 | * relay_close_buf - close a channel buffer | |
261 | * @buf: channel buffer | |
262 | * | |
263 | * Marks the buffer finalized and restores the default callbacks. | |
264 | * The channel buffer and channel buffer data structure are then freed | |
265 | * automatically when the last reference is given up. | |
266 | */ | |
267 | static void relay_close_buf(struct rchan_buf *buf) | |
268 | { | |
269 | del_timer_sync(&buf->timer); | |
270 | kref_put(&buf->kref, relay_remove_buf); | |
271 | } | |
272 | ||
273 | static void setup_callbacks(struct rchan *chan, | |
274 | struct rchan_callbacks *cb) | |
275 | { | |
276 | if (!cb) { | |
277 | chan->cb = &default_channel_callbacks; | |
278 | return; | |
279 | } | |
280 | ||
281 | if (!cb->create_buf_file) | |
282 | cb->create_buf_file = create_buf_file_default_callback; | |
283 | if (!cb->remove_buf_file) | |
284 | cb->remove_buf_file = remove_buf_file_default_callback; | |
285 | chan->cb = cb; | |
286 | } | |
287 | ||
288 | /** | |
289 | * relay_hotcpu_callback - CPU hotplug callback | |
290 | * @nb: notifier block | |
291 | * @action: hotplug action to take | |
292 | * @hcpu: CPU number | |
293 | * | |
294 | * Returns the success/failure of the operation. (%NOTIFY_OK, %NOTIFY_BAD) | |
295 | */ | |
296 | static int __cpuinit relay_hotcpu_callback(struct notifier_block *nb, | |
297 | unsigned long action, | |
298 | void *hcpu) | |
299 | { | |
300 | unsigned int hotcpu = (unsigned long)hcpu; | |
301 | struct rchan *chan; | |
302 | ||
303 | switch (action) { | |
304 | case CPU_UP_PREPARE: | |
305 | case CPU_UP_PREPARE_FROZEN: | |
306 | mutex_lock(&relay_channels_mutex); | |
307 | list_for_each_entry(chan, &relay_channels, list) { | |
308 | if (chan->buf[hotcpu]) | |
309 | continue; | |
310 | chan->buf[hotcpu] = relay_open_buf(chan, hotcpu); | |
311 | if (!chan->buf[hotcpu]) { | |
312 | printk(KERN_ERR | |
313 | "relay_hotcpu_callback: cpu %d buffer " | |
314 | "creation failed\n", hotcpu); | |
315 | mutex_unlock(&relay_channels_mutex); | |
316 | return NOTIFY_BAD; | |
317 | } | |
318 | } | |
319 | mutex_unlock(&relay_channels_mutex); | |
320 | break; | |
321 | case CPU_DEAD: | |
322 | case CPU_DEAD_FROZEN: | |
323 | /* No need to flush the cpu : will be flushed upon | |
324 | * final relay_flush() call. */ | |
325 | break; | |
326 | } | |
327 | return NOTIFY_OK; | |
328 | } | |
329 | ||
330 | /** | |
331 | * ltt_relay_open - create a new relay channel | |
332 | * @base_filename: base name of files to create | |
333 | * @parent: dentry of parent directory, %NULL for root directory | |
334 | * @subbuf_size: size of sub-buffers | |
335 | * @n_subbufs: number of sub-buffers | |
336 | * @cb: client callback functions | |
337 | * @private_data: user-defined data | |
338 | * | |
339 | * Returns channel pointer if successful, %NULL otherwise. | |
340 | * | |
341 | * Creates a channel buffer for each cpu using the sizes and | |
342 | * attributes specified. The created channel buffer files | |
343 | * will be named base_filename0...base_filenameN-1. File | |
344 | * permissions will be %S_IRUSR. | |
345 | */ | |
346 | struct rchan *ltt_relay_open(const char *base_filename, | |
347 | struct dentry *parent, | |
348 | size_t subbuf_size, | |
349 | size_t n_subbufs, | |
350 | struct rchan_callbacks *cb, | |
351 | void *private_data) | |
352 | { | |
353 | unsigned int i; | |
354 | struct rchan *chan; | |
355 | if (!base_filename) | |
356 | return NULL; | |
357 | ||
358 | if (!(subbuf_size && n_subbufs)) | |
359 | return NULL; | |
360 | ||
361 | chan = kzalloc(sizeof(struct rchan), GFP_KERNEL); | |
362 | if (!chan) | |
363 | return NULL; | |
364 | ||
365 | chan->version = LTT_RELAY_CHANNEL_VERSION; | |
366 | chan->n_subbufs = n_subbufs; | |
367 | chan->subbuf_size = subbuf_size; | |
368 | chan->subbuf_size_order = get_count_order(subbuf_size); | |
369 | chan->alloc_size = FIX_SIZE(subbuf_size * n_subbufs); | |
370 | chan->parent = parent; | |
371 | chan->private_data = private_data; | |
372 | strlcpy(chan->base_filename, base_filename, NAME_MAX); | |
373 | setup_callbacks(chan, cb); | |
374 | kref_init(&chan->kref); | |
375 | ||
376 | mutex_lock(&relay_channels_mutex); | |
377 | for_each_online_cpu(i) { | |
378 | chan->buf[i] = relay_open_buf(chan, i); | |
379 | if (!chan->buf[i]) | |
380 | goto free_bufs; | |
381 | } | |
382 | list_add(&chan->list, &relay_channels); | |
383 | mutex_unlock(&relay_channels_mutex); | |
384 | ||
385 | return chan; | |
386 | ||
387 | free_bufs: | |
388 | for_each_possible_cpu(i) { | |
389 | if (!chan->buf[i]) | |
390 | break; | |
391 | relay_close_buf(chan->buf[i]); | |
392 | } | |
393 | ||
394 | kref_put(&chan->kref, relay_destroy_channel); | |
395 | mutex_unlock(&relay_channels_mutex); | |
396 | return NULL; | |
397 | } | |
398 | EXPORT_SYMBOL_GPL(ltt_relay_open); | |
399 | ||
400 | /** | |
401 | * ltt_relay_close - close the channel | |
402 | * @chan: the channel | |
403 | * | |
404 | * Closes all channel buffers and frees the channel. | |
405 | */ | |
406 | void ltt_relay_close(struct rchan *chan) | |
407 | { | |
408 | unsigned int i; | |
409 | ||
410 | if (!chan) | |
411 | return; | |
412 | ||
413 | mutex_lock(&relay_channels_mutex); | |
414 | for_each_possible_cpu(i) | |
415 | if (chan->buf[i]) | |
416 | relay_close_buf(chan->buf[i]); | |
417 | ||
418 | list_del(&chan->list); | |
419 | kref_put(&chan->kref, relay_destroy_channel); | |
420 | mutex_unlock(&relay_channels_mutex); | |
421 | } | |
422 | EXPORT_SYMBOL_GPL(ltt_relay_close); | |
423 | ||
424 | /* | |
425 | * Start iteration at the previous element. Skip the real list head. | |
426 | */ | |
427 | struct buf_page *ltt_relay_find_prev_page(struct rchan_buf *buf, | |
428 | struct buf_page *page, size_t offset, ssize_t diff_offset) | |
429 | { | |
430 | struct buf_page *iter; | |
431 | size_t orig_iter_off; | |
432 | unsigned int i = 0; | |
433 | ||
434 | orig_iter_off = page->offset; | |
435 | list_for_each_entry_reverse(iter, &page->list, list) { | |
436 | /* | |
437 | * Skip the real list head. | |
438 | */ | |
439 | if (&iter->list == &buf->pages) | |
440 | continue; | |
441 | i++; | |
442 | if (offset >= iter->offset | |
443 | && offset < iter->offset + PAGE_SIZE) { | |
444 | #ifdef CONFIG_LTT_RELAY_CHECK_RANDOM_ACCESS | |
445 | if (i > 1) { | |
446 | printk(KERN_WARNING | |
447 | "Backward random access detected in " | |
448 | "ltt_relay. Iterations %u, " | |
449 | "offset %zu, orig iter->off %zu, " | |
450 | "iter->off %zu diff_offset %zd.\n", i, | |
451 | offset, orig_iter_off, iter->offset, | |
452 | diff_offset); | |
453 | WARN_ON(1); | |
454 | } | |
455 | #endif | |
456 | return iter; | |
457 | } | |
458 | } | |
459 | WARN_ON(1); | |
460 | return NULL; | |
461 | } | |
462 | EXPORT_SYMBOL_GPL(ltt_relay_find_prev_page); | |
463 | ||
464 | /* | |
465 | * Start iteration at the next element. Skip the real list head. | |
466 | */ | |
467 | struct buf_page *ltt_relay_find_next_page(struct rchan_buf *buf, | |
468 | struct buf_page *page, size_t offset, ssize_t diff_offset) | |
469 | { | |
470 | struct buf_page *iter; | |
471 | unsigned int i = 0; | |
472 | size_t orig_iter_off; | |
473 | ||
474 | orig_iter_off = page->offset; | |
475 | list_for_each_entry(iter, &page->list, list) { | |
476 | /* | |
477 | * Skip the real list head. | |
478 | */ | |
479 | if (&iter->list == &buf->pages) | |
480 | continue; | |
481 | i++; | |
482 | if (offset >= iter->offset | |
483 | && offset < iter->offset + PAGE_SIZE) { | |
484 | #ifdef CONFIG_LTT_RELAY_CHECK_RANDOM_ACCESS | |
485 | if (i > 1) { | |
486 | printk(KERN_WARNING | |
487 | "Forward random access detected in " | |
488 | "ltt_relay. Iterations %u, " | |
489 | "offset %zu, orig iter->off %zu, " | |
490 | "iter->off %zu diff_offset %zd.\n", i, | |
491 | offset, orig_iter_off, iter->offset, | |
492 | diff_offset); | |
493 | WARN_ON(1); | |
494 | } | |
495 | #endif | |
496 | return iter; | |
497 | } | |
498 | } | |
499 | WARN_ON(1); | |
500 | return NULL; | |
501 | } | |
502 | EXPORT_SYMBOL_GPL(ltt_relay_find_next_page); | |
503 | ||
504 | /** | |
505 | * ltt_relay_write - write data to a ltt_relay buffer. | |
506 | * @buf : buffer | |
507 | * @offset : offset within the buffer | |
508 | * @src : source address | |
509 | * @len : length to write | |
510 | * @page : cached buffer page | |
511 | * @pagecpy : page size copied so far | |
512 | */ | |
513 | void _ltt_relay_write(struct rchan_buf *buf, size_t offset, | |
514 | const void *src, size_t len, struct buf_page *page, ssize_t pagecpy) | |
515 | { | |
516 | do { | |
517 | len -= pagecpy; | |
518 | src += pagecpy; | |
519 | offset += pagecpy; | |
520 | /* | |
521 | * Underlying layer should never ask for writes across | |
522 | * subbuffers. | |
523 | */ | |
524 | WARN_ON(offset >= buf->chan->alloc_size); | |
525 | ||
526 | page = ltt_relay_cache_page(buf, &buf->wpage, page, offset); | |
527 | pagecpy = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK)); | |
528 | ltt_relay_do_copy(page_address(page->page) | |
529 | + (offset & ~PAGE_MASK), src, pagecpy); | |
530 | } while (unlikely(len != pagecpy)); | |
531 | } | |
532 | EXPORT_SYMBOL_GPL(_ltt_relay_write); | |
533 | ||
534 | /** | |
535 | * ltt_relay_read - read data from ltt_relay_buffer. | |
536 | * @buf : buffer | |
537 | * @offset : offset within the buffer | |
538 | * @dest : destination address | |
539 | * @len : length to write | |
540 | */ | |
541 | int ltt_relay_read(struct rchan_buf *buf, size_t offset, | |
542 | void *dest, size_t len) | |
543 | { | |
544 | struct buf_page *page; | |
545 | ssize_t pagecpy, orig_len; | |
546 | ||
547 | orig_len = len; | |
548 | offset &= buf->chan->alloc_size - 1; | |
549 | page = buf->rpage; | |
550 | if (unlikely(!len)) | |
551 | return 0; | |
552 | for (;;) { | |
553 | page = ltt_relay_cache_page(buf, &buf->rpage, page, offset); | |
554 | pagecpy = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK)); | |
555 | memcpy(dest, page_address(page->page) + (offset & ~PAGE_MASK), | |
556 | pagecpy); | |
557 | len -= pagecpy; | |
558 | if (likely(!len)) | |
559 | break; | |
560 | dest += pagecpy; | |
561 | offset += pagecpy; | |
562 | /* | |
563 | * Underlying layer should never ask for reads across | |
564 | * subbuffers. | |
565 | */ | |
566 | WARN_ON(offset >= buf->chan->alloc_size); | |
567 | } | |
568 | return orig_len; | |
569 | } | |
570 | EXPORT_SYMBOL_GPL(ltt_relay_read); | |
571 | ||
572 | /** | |
573 | * ltt_relay_read_get_page - Get a whole page to read from | |
574 | * @buf : buffer | |
575 | * @offset : offset within the buffer | |
576 | */ | |
577 | struct buf_page *ltt_relay_read_get_page(struct rchan_buf *buf, size_t offset) | |
578 | { | |
579 | struct buf_page *page; | |
580 | ||
581 | offset &= buf->chan->alloc_size - 1; | |
582 | page = buf->rpage; | |
583 | page = ltt_relay_cache_page(buf, &buf->rpage, page, offset); | |
584 | return page; | |
585 | } | |
586 | EXPORT_SYMBOL_GPL(ltt_relay_read_get_page); | |
587 | ||
588 | /** | |
589 | * ltt_relay_offset_address - get address of a location within the buffer | |
590 | * @buf : buffer | |
591 | * @offset : offset within the buffer. | |
592 | * | |
593 | * Return the address where a given offset is located. | |
594 | * Should be used to get the current subbuffer header pointer. Given we know | |
595 | * it's never on a page boundary, it's safe to write directly to this address, | |
596 | * as long as the write is never bigger than a page size. | |
597 | */ | |
598 | void *ltt_relay_offset_address(struct rchan_buf *buf, size_t offset) | |
599 | { | |
600 | struct buf_page *page; | |
601 | unsigned int odd; | |
602 | ||
603 | offset &= buf->chan->alloc_size - 1; | |
604 | odd = !!(offset & buf->chan->subbuf_size); | |
605 | page = buf->hpage[odd]; | |
606 | if (offset < page->offset || offset >= page->offset + PAGE_SIZE) | |
607 | buf->hpage[odd] = page = buf->wpage; | |
608 | page = ltt_relay_cache_page(buf, &buf->hpage[odd], page, offset); | |
609 | return page_address(page->page) + (offset & ~PAGE_MASK); | |
610 | } | |
611 | EXPORT_SYMBOL_GPL(ltt_relay_offset_address); | |
612 | ||
613 | /** | |
614 | * relay_file_open - open file op for relay files | |
615 | * @inode: the inode | |
616 | * @filp: the file | |
617 | * | |
618 | * Increments the channel buffer refcount. | |
619 | */ | |
620 | static int relay_file_open(struct inode *inode, struct file *filp) | |
621 | { | |
622 | struct rchan_buf *buf = inode->i_private; | |
623 | kref_get(&buf->kref); | |
624 | filp->private_data = buf; | |
625 | ||
626 | return nonseekable_open(inode, filp); | |
627 | } | |
628 | ||
629 | /** | |
630 | * relay_file_release - release file op for relay files | |
631 | * @inode: the inode | |
632 | * @filp: the file | |
633 | * | |
634 | * Decrements the channel refcount, as the filesystem is | |
635 | * no longer using it. | |
636 | */ | |
637 | static int relay_file_release(struct inode *inode, struct file *filp) | |
638 | { | |
639 | struct rchan_buf *buf = filp->private_data; | |
640 | kref_put(&buf->kref, relay_remove_buf); | |
641 | ||
642 | return 0; | |
643 | } | |
644 | ||
645 | const struct file_operations ltt_relay_file_operations = { | |
646 | .open = relay_file_open, | |
647 | .release = relay_file_release, | |
648 | }; | |
649 | EXPORT_SYMBOL_GPL(ltt_relay_file_operations); | |
650 | ||
651 | static __init int relay_init(void) | |
652 | { | |
653 | hotcpu_notifier(relay_hotcpu_callback, 5); | |
654 | return 0; | |
655 | } | |
656 | ||
657 | module_init(relay_init); |