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b86ff981 JA |
1 | /* |
2 | * Public API and common code for kernel->userspace relay file support. | |
3 | * | |
4 | * See Documentation/filesystems/relayfs.txt for an overview of relayfs. | |
5 | * | |
6 | * Copyright (C) 2002-2005 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp | |
7 | * Copyright (C) 1999-2005 - Karim Yaghmour (karim@opersys.com) | |
8 | * | |
9 | * Moved to kernel/relay.c by Paul Mundt, 2006. | |
10 | * | |
11 | * This file is released under the GPL. | |
12 | */ | |
13 | #include <linux/errno.h> | |
14 | #include <linux/stddef.h> | |
15 | #include <linux/slab.h> | |
16 | #include <linux/module.h> | |
17 | #include <linux/string.h> | |
18 | #include <linux/relay.h> | |
19 | #include <linux/vmalloc.h> | |
20 | #include <linux/mm.h> | |
21 | ||
22 | /* | |
23 | * close() vm_op implementation for relay file mapping. | |
24 | */ | |
25 | static void relay_file_mmap_close(struct vm_area_struct *vma) | |
26 | { | |
27 | struct rchan_buf *buf = vma->vm_private_data; | |
28 | buf->chan->cb->buf_unmapped(buf, vma->vm_file); | |
29 | } | |
30 | ||
31 | /* | |
32 | * nopage() vm_op implementation for relay file mapping. | |
33 | */ | |
34 | static struct page *relay_buf_nopage(struct vm_area_struct *vma, | |
35 | unsigned long address, | |
36 | int *type) | |
37 | { | |
38 | struct page *page; | |
39 | struct rchan_buf *buf = vma->vm_private_data; | |
40 | unsigned long offset = address - vma->vm_start; | |
41 | ||
42 | if (address > vma->vm_end) | |
43 | return NOPAGE_SIGBUS; /* Disallow mremap */ | |
44 | if (!buf) | |
45 | return NOPAGE_OOM; | |
46 | ||
47 | page = vmalloc_to_page(buf->start + offset); | |
48 | if (!page) | |
49 | return NOPAGE_OOM; | |
50 | get_page(page); | |
51 | ||
52 | if (type) | |
53 | *type = VM_FAULT_MINOR; | |
54 | ||
55 | return page; | |
56 | } | |
57 | ||
58 | /* | |
59 | * vm_ops for relay file mappings. | |
60 | */ | |
61 | static struct vm_operations_struct relay_file_mmap_ops = { | |
62 | .nopage = relay_buf_nopage, | |
63 | .close = relay_file_mmap_close, | |
64 | }; | |
65 | ||
66 | /** | |
67 | * relay_mmap_buf: - mmap channel buffer to process address space | |
68 | * @buf: relay channel buffer | |
69 | * @vma: vm_area_struct describing memory to be mapped | |
70 | * | |
71 | * Returns 0 if ok, negative on error | |
72 | * | |
73 | * Caller should already have grabbed mmap_sem. | |
74 | */ | |
75 | int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma) | |
76 | { | |
77 | unsigned long length = vma->vm_end - vma->vm_start; | |
78 | struct file *filp = vma->vm_file; | |
79 | ||
80 | if (!buf) | |
81 | return -EBADF; | |
82 | ||
83 | if (length != (unsigned long)buf->chan->alloc_size) | |
84 | return -EINVAL; | |
85 | ||
86 | vma->vm_ops = &relay_file_mmap_ops; | |
87 | vma->vm_private_data = buf; | |
88 | buf->chan->cb->buf_mapped(buf, filp); | |
89 | ||
90 | return 0; | |
91 | } | |
92 | ||
93 | /** | |
94 | * relay_alloc_buf - allocate a channel buffer | |
95 | * @buf: the buffer struct | |
96 | * @size: total size of the buffer | |
97 | * | |
98 | * Returns a pointer to the resulting buffer, NULL if unsuccessful | |
99 | */ | |
100 | static void *relay_alloc_buf(struct rchan_buf *buf, unsigned long size) | |
101 | { | |
102 | void *mem; | |
103 | unsigned int i, j, n_pages; | |
104 | ||
105 | size = PAGE_ALIGN(size); | |
106 | n_pages = size >> PAGE_SHIFT; | |
107 | ||
108 | buf->page_array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL); | |
109 | if (!buf->page_array) | |
110 | return NULL; | |
111 | ||
112 | for (i = 0; i < n_pages; i++) { | |
113 | buf->page_array[i] = alloc_page(GFP_KERNEL); | |
114 | if (unlikely(!buf->page_array[i])) | |
115 | goto depopulate; | |
116 | } | |
117 | mem = vmap(buf->page_array, n_pages, VM_MAP, PAGE_KERNEL); | |
118 | if (!mem) | |
119 | goto depopulate; | |
120 | ||
121 | memset(mem, 0, size); | |
122 | buf->page_count = n_pages; | |
123 | return mem; | |
124 | ||
125 | depopulate: | |
126 | for (j = 0; j < i; j++) | |
127 | __free_page(buf->page_array[j]); | |
128 | kfree(buf->page_array); | |
129 | return NULL; | |
130 | } | |
131 | ||
132 | /** | |
133 | * relay_create_buf - allocate and initialize a channel buffer | |
134 | * @alloc_size: size of the buffer to allocate | |
135 | * @n_subbufs: number of sub-buffers in the channel | |
136 | * | |
137 | * Returns channel buffer if successful, NULL otherwise | |
138 | */ | |
139 | struct rchan_buf *relay_create_buf(struct rchan *chan) | |
140 | { | |
141 | struct rchan_buf *buf = kcalloc(1, sizeof(struct rchan_buf), GFP_KERNEL); | |
142 | if (!buf) | |
143 | return NULL; | |
144 | ||
145 | buf->padding = kmalloc(chan->n_subbufs * sizeof(size_t *), GFP_KERNEL); | |
146 | if (!buf->padding) | |
147 | goto free_buf; | |
148 | ||
149 | buf->start = relay_alloc_buf(buf, chan->alloc_size); | |
150 | if (!buf->start) | |
151 | goto free_buf; | |
152 | ||
153 | buf->chan = chan; | |
154 | kref_get(&buf->chan->kref); | |
155 | return buf; | |
156 | ||
157 | free_buf: | |
158 | kfree(buf->padding); | |
159 | kfree(buf); | |
160 | return NULL; | |
161 | } | |
162 | ||
163 | /** | |
164 | * relay_destroy_channel - free the channel struct | |
165 | * | |
166 | * Should only be called from kref_put(). | |
167 | */ | |
168 | void relay_destroy_channel(struct kref *kref) | |
169 | { | |
170 | struct rchan *chan = container_of(kref, struct rchan, kref); | |
171 | kfree(chan); | |
172 | } | |
173 | ||
174 | /** | |
175 | * relay_destroy_buf - destroy an rchan_buf struct and associated buffer | |
176 | * @buf: the buffer struct | |
177 | */ | |
178 | void relay_destroy_buf(struct rchan_buf *buf) | |
179 | { | |
180 | struct rchan *chan = buf->chan; | |
181 | unsigned int i; | |
182 | ||
183 | if (likely(buf->start)) { | |
184 | vunmap(buf->start); | |
185 | for (i = 0; i < buf->page_count; i++) | |
186 | __free_page(buf->page_array[i]); | |
187 | kfree(buf->page_array); | |
188 | } | |
189 | kfree(buf->padding); | |
190 | kfree(buf); | |
191 | kref_put(&chan->kref, relay_destroy_channel); | |
192 | } | |
193 | ||
194 | /** | |
195 | * relay_remove_buf - remove a channel buffer | |
196 | * | |
197 | * Removes the file from the fileystem, which also frees the | |
198 | * rchan_buf_struct and the channel buffer. Should only be called from | |
199 | * kref_put(). | |
200 | */ | |
201 | void relay_remove_buf(struct kref *kref) | |
202 | { | |
203 | struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref); | |
204 | buf->chan->cb->remove_buf_file(buf->dentry); | |
205 | relay_destroy_buf(buf); | |
206 | } | |
207 | ||
208 | /** | |
209 | * relay_buf_empty - boolean, is the channel buffer empty? | |
210 | * @buf: channel buffer | |
211 | * | |
212 | * Returns 1 if the buffer is empty, 0 otherwise. | |
213 | */ | |
214 | int relay_buf_empty(struct rchan_buf *buf) | |
215 | { | |
216 | return (buf->subbufs_produced - buf->subbufs_consumed) ? 0 : 1; | |
217 | } | |
218 | EXPORT_SYMBOL_GPL(relay_buf_empty); | |
219 | ||
220 | /** | |
221 | * relay_buf_full - boolean, is the channel buffer full? | |
222 | * @buf: channel buffer | |
223 | * | |
224 | * Returns 1 if the buffer is full, 0 otherwise. | |
225 | */ | |
226 | int relay_buf_full(struct rchan_buf *buf) | |
227 | { | |
228 | size_t ready = buf->subbufs_produced - buf->subbufs_consumed; | |
229 | return (ready >= buf->chan->n_subbufs) ? 1 : 0; | |
230 | } | |
231 | EXPORT_SYMBOL_GPL(relay_buf_full); | |
232 | ||
233 | /* | |
234 | * High-level relay kernel API and associated functions. | |
235 | */ | |
236 | ||
237 | /* | |
238 | * rchan_callback implementations defining default channel behavior. Used | |
239 | * in place of corresponding NULL values in client callback struct. | |
240 | */ | |
241 | ||
242 | /* | |
243 | * subbuf_start() default callback. Does nothing. | |
244 | */ | |
245 | static int subbuf_start_default_callback (struct rchan_buf *buf, | |
246 | void *subbuf, | |
247 | void *prev_subbuf, | |
248 | size_t prev_padding) | |
249 | { | |
250 | if (relay_buf_full(buf)) | |
251 | return 0; | |
252 | ||
253 | return 1; | |
254 | } | |
255 | ||
256 | /* | |
257 | * buf_mapped() default callback. Does nothing. | |
258 | */ | |
259 | static void buf_mapped_default_callback(struct rchan_buf *buf, | |
260 | struct file *filp) | |
261 | { | |
262 | } | |
263 | ||
264 | /* | |
265 | * buf_unmapped() default callback. Does nothing. | |
266 | */ | |
267 | static void buf_unmapped_default_callback(struct rchan_buf *buf, | |
268 | struct file *filp) | |
269 | { | |
270 | } | |
271 | ||
272 | /* | |
273 | * create_buf_file_create() default callback. Does nothing. | |
274 | */ | |
275 | static struct dentry *create_buf_file_default_callback(const char *filename, | |
276 | struct dentry *parent, | |
277 | int mode, | |
278 | struct rchan_buf *buf, | |
279 | int *is_global) | |
280 | { | |
281 | return NULL; | |
282 | } | |
283 | ||
284 | /* | |
285 | * remove_buf_file() default callback. Does nothing. | |
286 | */ | |
287 | static int remove_buf_file_default_callback(struct dentry *dentry) | |
288 | { | |
289 | return -EINVAL; | |
290 | } | |
291 | ||
292 | /* relay channel default callbacks */ | |
293 | static struct rchan_callbacks default_channel_callbacks = { | |
294 | .subbuf_start = subbuf_start_default_callback, | |
295 | .buf_mapped = buf_mapped_default_callback, | |
296 | .buf_unmapped = buf_unmapped_default_callback, | |
297 | .create_buf_file = create_buf_file_default_callback, | |
298 | .remove_buf_file = remove_buf_file_default_callback, | |
299 | }; | |
300 | ||
301 | /** | |
302 | * wakeup_readers - wake up readers waiting on a channel | |
303 | * @private: the channel buffer | |
304 | * | |
305 | * This is the work function used to defer reader waking. The | |
306 | * reason waking is deferred is that calling directly from write | |
307 | * causes problems if you're writing from say the scheduler. | |
308 | */ | |
309 | static void wakeup_readers(void *private) | |
310 | { | |
311 | struct rchan_buf *buf = private; | |
312 | wake_up_interruptible(&buf->read_wait); | |
313 | } | |
314 | ||
315 | /** | |
316 | * __relay_reset - reset a channel buffer | |
317 | * @buf: the channel buffer | |
318 | * @init: 1 if this is a first-time initialization | |
319 | * | |
320 | * See relay_reset for description of effect. | |
321 | */ | |
322 | static inline void __relay_reset(struct rchan_buf *buf, unsigned int init) | |
323 | { | |
324 | size_t i; | |
325 | ||
326 | if (init) { | |
327 | init_waitqueue_head(&buf->read_wait); | |
328 | kref_init(&buf->kref); | |
329 | INIT_WORK(&buf->wake_readers, NULL, NULL); | |
330 | } else { | |
331 | cancel_delayed_work(&buf->wake_readers); | |
332 | flush_scheduled_work(); | |
333 | } | |
334 | ||
335 | buf->subbufs_produced = 0; | |
336 | buf->subbufs_consumed = 0; | |
337 | buf->bytes_consumed = 0; | |
338 | buf->finalized = 0; | |
339 | buf->data = buf->start; | |
340 | buf->offset = 0; | |
341 | ||
342 | for (i = 0; i < buf->chan->n_subbufs; i++) | |
343 | buf->padding[i] = 0; | |
344 | ||
345 | buf->chan->cb->subbuf_start(buf, buf->data, NULL, 0); | |
346 | } | |
347 | ||
348 | /** | |
349 | * relay_reset - reset the channel | |
350 | * @chan: the channel | |
351 | * | |
352 | * This has the effect of erasing all data from all channel buffers | |
353 | * and restarting the channel in its initial state. The buffers | |
354 | * are not freed, so any mappings are still in effect. | |
355 | * | |
356 | * NOTE: Care should be taken that the channel isn't actually | |
357 | * being used by anything when this call is made. | |
358 | */ | |
359 | void relay_reset(struct rchan *chan) | |
360 | { | |
361 | unsigned int i; | |
362 | struct rchan_buf *prev = NULL; | |
363 | ||
364 | if (!chan) | |
365 | return; | |
366 | ||
367 | for (i = 0; i < NR_CPUS; i++) { | |
368 | if (!chan->buf[i] || chan->buf[i] == prev) | |
369 | break; | |
370 | __relay_reset(chan->buf[i], 0); | |
371 | prev = chan->buf[i]; | |
372 | } | |
373 | } | |
374 | EXPORT_SYMBOL_GPL(relay_reset); | |
375 | ||
376 | /** | |
377 | * relay_open_buf - create a new relay channel buffer | |
378 | * | |
379 | * Internal - used by relay_open(). | |
380 | */ | |
381 | static struct rchan_buf *relay_open_buf(struct rchan *chan, | |
382 | const char *filename, | |
383 | struct dentry *parent, | |
384 | int *is_global) | |
385 | { | |
386 | struct rchan_buf *buf; | |
387 | struct dentry *dentry; | |
388 | ||
389 | if (*is_global) | |
390 | return chan->buf[0]; | |
391 | ||
392 | buf = relay_create_buf(chan); | |
393 | if (!buf) | |
394 | return NULL; | |
395 | ||
396 | /* Create file in fs */ | |
397 | dentry = chan->cb->create_buf_file(filename, parent, S_IRUSR, | |
398 | buf, is_global); | |
399 | if (!dentry) { | |
400 | relay_destroy_buf(buf); | |
401 | return NULL; | |
402 | } | |
403 | ||
404 | buf->dentry = dentry; | |
405 | __relay_reset(buf, 1); | |
406 | ||
407 | return buf; | |
408 | } | |
409 | ||
410 | /** | |
411 | * relay_close_buf - close a channel buffer | |
412 | * @buf: channel buffer | |
413 | * | |
414 | * Marks the buffer finalized and restores the default callbacks. | |
415 | * The channel buffer and channel buffer data structure are then freed | |
416 | * automatically when the last reference is given up. | |
417 | */ | |
418 | static inline void relay_close_buf(struct rchan_buf *buf) | |
419 | { | |
420 | buf->finalized = 1; | |
421 | cancel_delayed_work(&buf->wake_readers); | |
422 | flush_scheduled_work(); | |
423 | kref_put(&buf->kref, relay_remove_buf); | |
424 | } | |
425 | ||
426 | static inline void setup_callbacks(struct rchan *chan, | |
427 | struct rchan_callbacks *cb) | |
428 | { | |
429 | if (!cb) { | |
430 | chan->cb = &default_channel_callbacks; | |
431 | return; | |
432 | } | |
433 | ||
434 | if (!cb->subbuf_start) | |
435 | cb->subbuf_start = subbuf_start_default_callback; | |
436 | if (!cb->buf_mapped) | |
437 | cb->buf_mapped = buf_mapped_default_callback; | |
438 | if (!cb->buf_unmapped) | |
439 | cb->buf_unmapped = buf_unmapped_default_callback; | |
440 | if (!cb->create_buf_file) | |
441 | cb->create_buf_file = create_buf_file_default_callback; | |
442 | if (!cb->remove_buf_file) | |
443 | cb->remove_buf_file = remove_buf_file_default_callback; | |
444 | chan->cb = cb; | |
445 | } | |
446 | ||
447 | /** | |
448 | * relay_open - create a new relay channel | |
449 | * @base_filename: base name of files to create | |
450 | * @parent: dentry of parent directory, NULL for root directory | |
451 | * @subbuf_size: size of sub-buffers | |
452 | * @n_subbufs: number of sub-buffers | |
453 | * @cb: client callback functions | |
454 | * | |
455 | * Returns channel pointer if successful, NULL otherwise. | |
456 | * | |
457 | * Creates a channel buffer for each cpu using the sizes and | |
458 | * attributes specified. The created channel buffer files | |
459 | * will be named base_filename0...base_filenameN-1. File | |
460 | * permissions will be S_IRUSR. | |
461 | */ | |
462 | struct rchan *relay_open(const char *base_filename, | |
463 | struct dentry *parent, | |
464 | size_t subbuf_size, | |
465 | size_t n_subbufs, | |
466 | struct rchan_callbacks *cb) | |
467 | { | |
468 | unsigned int i; | |
469 | struct rchan *chan; | |
470 | char *tmpname; | |
471 | int is_global = 0; | |
472 | ||
473 | if (!base_filename) | |
474 | return NULL; | |
475 | ||
476 | if (!(subbuf_size && n_subbufs)) | |
477 | return NULL; | |
478 | ||
479 | chan = kcalloc(1, sizeof(struct rchan), GFP_KERNEL); | |
480 | if (!chan) | |
481 | return NULL; | |
482 | ||
483 | chan->version = RELAYFS_CHANNEL_VERSION; | |
484 | chan->n_subbufs = n_subbufs; | |
485 | chan->subbuf_size = subbuf_size; | |
486 | chan->alloc_size = FIX_SIZE(subbuf_size * n_subbufs); | |
487 | setup_callbacks(chan, cb); | |
488 | kref_init(&chan->kref); | |
489 | ||
490 | tmpname = kmalloc(NAME_MAX + 1, GFP_KERNEL); | |
491 | if (!tmpname) | |
492 | goto free_chan; | |
493 | ||
494 | for_each_online_cpu(i) { | |
495 | sprintf(tmpname, "%s%d", base_filename, i); | |
496 | chan->buf[i] = relay_open_buf(chan, tmpname, parent, | |
497 | &is_global); | |
498 | if (!chan->buf[i]) | |
499 | goto free_bufs; | |
500 | ||
501 | chan->buf[i]->cpu = i; | |
502 | } | |
503 | ||
504 | kfree(tmpname); | |
505 | return chan; | |
506 | ||
507 | free_bufs: | |
508 | for (i = 0; i < NR_CPUS; i++) { | |
509 | if (!chan->buf[i]) | |
510 | break; | |
511 | relay_close_buf(chan->buf[i]); | |
512 | if (is_global) | |
513 | break; | |
514 | } | |
515 | kfree(tmpname); | |
516 | ||
517 | free_chan: | |
518 | kref_put(&chan->kref, relay_destroy_channel); | |
519 | return NULL; | |
520 | } | |
521 | EXPORT_SYMBOL_GPL(relay_open); | |
522 | ||
523 | /** | |
524 | * relay_switch_subbuf - switch to a new sub-buffer | |
525 | * @buf: channel buffer | |
526 | * @length: size of current event | |
527 | * | |
528 | * Returns either the length passed in or 0 if full. | |
529 | * | |
530 | * Performs sub-buffer-switch tasks such as invoking callbacks, | |
531 | * updating padding counts, waking up readers, etc. | |
532 | */ | |
533 | size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length) | |
534 | { | |
535 | void *old, *new; | |
536 | size_t old_subbuf, new_subbuf; | |
537 | ||
538 | if (unlikely(length > buf->chan->subbuf_size)) | |
539 | goto toobig; | |
540 | ||
541 | if (buf->offset != buf->chan->subbuf_size + 1) { | |
542 | buf->prev_padding = buf->chan->subbuf_size - buf->offset; | |
543 | old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; | |
544 | buf->padding[old_subbuf] = buf->prev_padding; | |
545 | buf->subbufs_produced++; | |
546 | if (waitqueue_active(&buf->read_wait)) { | |
547 | PREPARE_WORK(&buf->wake_readers, wakeup_readers, buf); | |
548 | schedule_delayed_work(&buf->wake_readers, 1); | |
549 | } | |
550 | } | |
551 | ||
552 | old = buf->data; | |
553 | new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; | |
554 | new = buf->start + new_subbuf * buf->chan->subbuf_size; | |
555 | buf->offset = 0; | |
556 | if (!buf->chan->cb->subbuf_start(buf, new, old, buf->prev_padding)) { | |
557 | buf->offset = buf->chan->subbuf_size + 1; | |
558 | return 0; | |
559 | } | |
560 | buf->data = new; | |
561 | buf->padding[new_subbuf] = 0; | |
562 | ||
563 | if (unlikely(length + buf->offset > buf->chan->subbuf_size)) | |
564 | goto toobig; | |
565 | ||
566 | return length; | |
567 | ||
568 | toobig: | |
569 | buf->chan->last_toobig = length; | |
570 | return 0; | |
571 | } | |
572 | EXPORT_SYMBOL_GPL(relay_switch_subbuf); | |
573 | ||
574 | /** | |
575 | * relay_subbufs_consumed - update the buffer's sub-buffers-consumed count | |
576 | * @chan: the channel | |
577 | * @cpu: the cpu associated with the channel buffer to update | |
578 | * @subbufs_consumed: number of sub-buffers to add to current buf's count | |
579 | * | |
580 | * Adds to the channel buffer's consumed sub-buffer count. | |
581 | * subbufs_consumed should be the number of sub-buffers newly consumed, | |
582 | * not the total consumed. | |
583 | * | |
584 | * NOTE: kernel clients don't need to call this function if the channel | |
585 | * mode is 'overwrite'. | |
586 | */ | |
587 | void relay_subbufs_consumed(struct rchan *chan, | |
588 | unsigned int cpu, | |
589 | size_t subbufs_consumed) | |
590 | { | |
591 | struct rchan_buf *buf; | |
592 | ||
593 | if (!chan) | |
594 | return; | |
595 | ||
596 | if (cpu >= NR_CPUS || !chan->buf[cpu]) | |
597 | return; | |
598 | ||
599 | buf = chan->buf[cpu]; | |
600 | buf->subbufs_consumed += subbufs_consumed; | |
601 | if (buf->subbufs_consumed > buf->subbufs_produced) | |
602 | buf->subbufs_consumed = buf->subbufs_produced; | |
603 | } | |
604 | EXPORT_SYMBOL_GPL(relay_subbufs_consumed); | |
605 | ||
606 | /** | |
607 | * relay_close - close the channel | |
608 | * @chan: the channel | |
609 | * | |
610 | * Closes all channel buffers and frees the channel. | |
611 | */ | |
612 | void relay_close(struct rchan *chan) | |
613 | { | |
614 | unsigned int i; | |
615 | struct rchan_buf *prev = NULL; | |
616 | ||
617 | if (!chan) | |
618 | return; | |
619 | ||
620 | for (i = 0; i < NR_CPUS; i++) { | |
621 | if (!chan->buf[i] || chan->buf[i] == prev) | |
622 | break; | |
623 | relay_close_buf(chan->buf[i]); | |
624 | prev = chan->buf[i]; | |
625 | } | |
626 | ||
627 | if (chan->last_toobig) | |
628 | printk(KERN_WARNING "relay: one or more items not logged " | |
629 | "[item size (%Zd) > sub-buffer size (%Zd)]\n", | |
630 | chan->last_toobig, chan->subbuf_size); | |
631 | ||
632 | kref_put(&chan->kref, relay_destroy_channel); | |
633 | } | |
634 | EXPORT_SYMBOL_GPL(relay_close); | |
635 | ||
636 | /** | |
637 | * relay_flush - close the channel | |
638 | * @chan: the channel | |
639 | * | |
640 | * Flushes all channel buffers i.e. forces buffer switch. | |
641 | */ | |
642 | void relay_flush(struct rchan *chan) | |
643 | { | |
644 | unsigned int i; | |
645 | struct rchan_buf *prev = NULL; | |
646 | ||
647 | if (!chan) | |
648 | return; | |
649 | ||
650 | for (i = 0; i < NR_CPUS; i++) { | |
651 | if (!chan->buf[i] || chan->buf[i] == prev) | |
652 | break; | |
653 | relay_switch_subbuf(chan->buf[i], 0); | |
654 | prev = chan->buf[i]; | |
655 | } | |
656 | } | |
657 | EXPORT_SYMBOL_GPL(relay_flush); | |
658 | ||
659 | /** | |
660 | * relay_file_open - open file op for relay files | |
661 | * @inode: the inode | |
662 | * @filp: the file | |
663 | * | |
664 | * Increments the channel buffer refcount. | |
665 | */ | |
666 | static int relay_file_open(struct inode *inode, struct file *filp) | |
667 | { | |
668 | struct rchan_buf *buf = inode->u.generic_ip; | |
669 | kref_get(&buf->kref); | |
670 | filp->private_data = buf; | |
671 | ||
672 | return 0; | |
673 | } | |
674 | ||
675 | /** | |
676 | * relay_file_mmap - mmap file op for relay files | |
677 | * @filp: the file | |
678 | * @vma: the vma describing what to map | |
679 | * | |
680 | * Calls upon relay_mmap_buf to map the file into user space. | |
681 | */ | |
682 | static int relay_file_mmap(struct file *filp, struct vm_area_struct *vma) | |
683 | { | |
684 | struct rchan_buf *buf = filp->private_data; | |
685 | return relay_mmap_buf(buf, vma); | |
686 | } | |
687 | ||
688 | /** | |
689 | * relay_file_poll - poll file op for relay files | |
690 | * @filp: the file | |
691 | * @wait: poll table | |
692 | * | |
693 | * Poll implemention. | |
694 | */ | |
695 | static unsigned int relay_file_poll(struct file *filp, poll_table *wait) | |
696 | { | |
697 | unsigned int mask = 0; | |
698 | struct rchan_buf *buf = filp->private_data; | |
699 | ||
700 | if (buf->finalized) | |
701 | return POLLERR; | |
702 | ||
703 | if (filp->f_mode & FMODE_READ) { | |
704 | poll_wait(filp, &buf->read_wait, wait); | |
705 | if (!relay_buf_empty(buf)) | |
706 | mask |= POLLIN | POLLRDNORM; | |
707 | } | |
708 | ||
709 | return mask; | |
710 | } | |
711 | ||
712 | /** | |
713 | * relay_file_release - release file op for relay files | |
714 | * @inode: the inode | |
715 | * @filp: the file | |
716 | * | |
717 | * Decrements the channel refcount, as the filesystem is | |
718 | * no longer using it. | |
719 | */ | |
720 | static int relay_file_release(struct inode *inode, struct file *filp) | |
721 | { | |
722 | struct rchan_buf *buf = filp->private_data; | |
723 | kref_put(&buf->kref, relay_remove_buf); | |
724 | ||
725 | return 0; | |
726 | } | |
727 | ||
728 | /** | |
729 | * relay_file_read_consume - update the consumed count for the buffer | |
730 | */ | |
731 | static void relay_file_read_consume(struct rchan_buf *buf, | |
732 | size_t read_pos, | |
733 | size_t bytes_consumed) | |
734 | { | |
735 | size_t subbuf_size = buf->chan->subbuf_size; | |
736 | size_t n_subbufs = buf->chan->n_subbufs; | |
737 | size_t read_subbuf; | |
738 | ||
739 | if (buf->bytes_consumed + bytes_consumed > subbuf_size) { | |
740 | relay_subbufs_consumed(buf->chan, buf->cpu, 1); | |
741 | buf->bytes_consumed = 0; | |
742 | } | |
743 | ||
744 | buf->bytes_consumed += bytes_consumed; | |
745 | read_subbuf = read_pos / buf->chan->subbuf_size; | |
746 | if (buf->bytes_consumed + buf->padding[read_subbuf] == subbuf_size) { | |
747 | if ((read_subbuf == buf->subbufs_produced % n_subbufs) && | |
748 | (buf->offset == subbuf_size)) | |
749 | return; | |
750 | relay_subbufs_consumed(buf->chan, buf->cpu, 1); | |
751 | buf->bytes_consumed = 0; | |
752 | } | |
753 | } | |
754 | ||
755 | /** | |
756 | * relay_file_read_avail - boolean, are there unconsumed bytes available? | |
757 | */ | |
758 | static int relay_file_read_avail(struct rchan_buf *buf, size_t read_pos) | |
759 | { | |
760 | size_t bytes_produced, bytes_consumed, write_offset; | |
761 | size_t subbuf_size = buf->chan->subbuf_size; | |
762 | size_t n_subbufs = buf->chan->n_subbufs; | |
763 | size_t produced = buf->subbufs_produced % n_subbufs; | |
764 | size_t consumed = buf->subbufs_consumed % n_subbufs; | |
765 | ||
766 | write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset; | |
767 | ||
768 | if (consumed > produced) { | |
769 | if ((produced > n_subbufs) && | |
770 | (produced + n_subbufs - consumed <= n_subbufs)) | |
771 | produced += n_subbufs; | |
772 | } else if (consumed == produced) { | |
773 | if (buf->offset > subbuf_size) { | |
774 | produced += n_subbufs; | |
775 | if (buf->subbufs_produced == buf->subbufs_consumed) | |
776 | consumed += n_subbufs; | |
777 | } | |
778 | } | |
779 | ||
780 | if (buf->offset > subbuf_size) | |
781 | bytes_produced = (produced - 1) * subbuf_size + write_offset; | |
782 | else | |
783 | bytes_produced = produced * subbuf_size + write_offset; | |
784 | bytes_consumed = consumed * subbuf_size + buf->bytes_consumed; | |
785 | ||
786 | if (bytes_produced == bytes_consumed) | |
787 | return 0; | |
788 | ||
789 | relay_file_read_consume(buf, read_pos, 0); | |
790 | ||
791 | return 1; | |
792 | } | |
793 | ||
794 | /** | |
795 | * relay_file_read_subbuf_avail - return bytes available in sub-buffer | |
796 | */ | |
797 | static size_t relay_file_read_subbuf_avail(size_t read_pos, | |
798 | struct rchan_buf *buf) | |
799 | { | |
800 | size_t padding, avail = 0; | |
801 | size_t read_subbuf, read_offset, write_subbuf, write_offset; | |
802 | size_t subbuf_size = buf->chan->subbuf_size; | |
803 | ||
804 | write_subbuf = (buf->data - buf->start) / subbuf_size; | |
805 | write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset; | |
806 | read_subbuf = read_pos / subbuf_size; | |
807 | read_offset = read_pos % subbuf_size; | |
808 | padding = buf->padding[read_subbuf]; | |
809 | ||
810 | if (read_subbuf == write_subbuf) { | |
811 | if (read_offset + padding < write_offset) | |
812 | avail = write_offset - (read_offset + padding); | |
813 | } else | |
814 | avail = (subbuf_size - padding) - read_offset; | |
815 | ||
816 | return avail; | |
817 | } | |
818 | ||
819 | /** | |
820 | * relay_file_read_start_pos - find the first available byte to read | |
821 | * | |
822 | * If the read_pos is in the middle of padding, return the | |
823 | * position of the first actually available byte, otherwise | |
824 | * return the original value. | |
825 | */ | |
826 | static size_t relay_file_read_start_pos(size_t read_pos, | |
827 | struct rchan_buf *buf) | |
828 | { | |
829 | size_t read_subbuf, padding, padding_start, padding_end; | |
830 | size_t subbuf_size = buf->chan->subbuf_size; | |
831 | size_t n_subbufs = buf->chan->n_subbufs; | |
832 | ||
833 | read_subbuf = read_pos / subbuf_size; | |
834 | padding = buf->padding[read_subbuf]; | |
835 | padding_start = (read_subbuf + 1) * subbuf_size - padding; | |
836 | padding_end = (read_subbuf + 1) * subbuf_size; | |
837 | if (read_pos >= padding_start && read_pos < padding_end) { | |
838 | read_subbuf = (read_subbuf + 1) % n_subbufs; | |
839 | read_pos = read_subbuf * subbuf_size; | |
840 | } | |
841 | ||
842 | return read_pos; | |
843 | } | |
844 | ||
845 | /** | |
846 | * relay_file_read_end_pos - return the new read position | |
847 | */ | |
848 | static size_t relay_file_read_end_pos(struct rchan_buf *buf, | |
849 | size_t read_pos, | |
850 | size_t count) | |
851 | { | |
852 | size_t read_subbuf, padding, end_pos; | |
853 | size_t subbuf_size = buf->chan->subbuf_size; | |
854 | size_t n_subbufs = buf->chan->n_subbufs; | |
855 | ||
856 | read_subbuf = read_pos / subbuf_size; | |
857 | padding = buf->padding[read_subbuf]; | |
858 | if (read_pos % subbuf_size + count + padding == subbuf_size) | |
859 | end_pos = (read_subbuf + 1) * subbuf_size; | |
860 | else | |
861 | end_pos = read_pos + count; | |
862 | if (end_pos >= subbuf_size * n_subbufs) | |
863 | end_pos = 0; | |
864 | ||
865 | return end_pos; | |
866 | } | |
867 | ||
868 | /** | |
869 | * relay_file_read - read file op for relay files | |
870 | * @filp: the file | |
871 | * @buffer: the userspace buffer | |
872 | * @count: number of bytes to read | |
873 | * @ppos: position to read from | |
874 | * | |
875 | * Reads count bytes or the number of bytes available in the | |
876 | * current sub-buffer being read, whichever is smaller. | |
877 | */ | |
878 | static ssize_t relay_file_read(struct file *filp, | |
879 | char __user *buffer, | |
880 | size_t count, | |
881 | loff_t *ppos) | |
882 | { | |
883 | struct rchan_buf *buf = filp->private_data; | |
884 | struct inode *inode = filp->f_dentry->d_inode; | |
885 | size_t read_start, avail; | |
886 | ssize_t ret = 0; | |
887 | void *from; | |
888 | ||
889 | mutex_lock(&inode->i_mutex); | |
890 | if(!relay_file_read_avail(buf, *ppos)) | |
891 | goto out; | |
892 | ||
893 | read_start = relay_file_read_start_pos(*ppos, buf); | |
894 | avail = relay_file_read_subbuf_avail(read_start, buf); | |
895 | if (!avail) | |
896 | goto out; | |
897 | ||
898 | from = buf->start + read_start; | |
899 | ret = count = min(count, avail); | |
900 | if (copy_to_user(buffer, from, count)) { | |
901 | ret = -EFAULT; | |
902 | goto out; | |
903 | } | |
904 | relay_file_read_consume(buf, read_start, count); | |
905 | *ppos = relay_file_read_end_pos(buf, read_start, count); | |
906 | out: | |
907 | mutex_unlock(&inode->i_mutex); | |
908 | return ret; | |
909 | } | |
910 | ||
911 | struct file_operations relay_file_operations = { | |
912 | .open = relay_file_open, | |
913 | .poll = relay_file_poll, | |
914 | .mmap = relay_file_mmap, | |
915 | .read = relay_file_read, | |
916 | .llseek = no_llseek, | |
917 | .release = relay_file_release, | |
918 | }; | |
919 | EXPORT_SYMBOL_GPL(relay_file_operations); |