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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 | * | |
221415d7 JA |
98 | * Returns a pointer to the resulting buffer, NULL if unsuccessful. The |
99 | * passed in size will get page aligned, if it isn't already. | |
b86ff981 | 100 | */ |
221415d7 | 101 | static void *relay_alloc_buf(struct rchan_buf *buf, size_t *size) |
b86ff981 JA |
102 | { |
103 | void *mem; | |
104 | unsigned int i, j, n_pages; | |
105 | ||
221415d7 JA |
106 | *size = PAGE_ALIGN(*size); |
107 | n_pages = *size >> PAGE_SHIFT; | |
b86ff981 JA |
108 | |
109 | buf->page_array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL); | |
110 | if (!buf->page_array) | |
111 | return NULL; | |
112 | ||
113 | for (i = 0; i < n_pages; i++) { | |
114 | buf->page_array[i] = alloc_page(GFP_KERNEL); | |
115 | if (unlikely(!buf->page_array[i])) | |
116 | goto depopulate; | |
117 | } | |
118 | mem = vmap(buf->page_array, n_pages, VM_MAP, PAGE_KERNEL); | |
119 | if (!mem) | |
120 | goto depopulate; | |
121 | ||
221415d7 | 122 | memset(mem, 0, *size); |
b86ff981 JA |
123 | buf->page_count = n_pages; |
124 | return mem; | |
125 | ||
126 | depopulate: | |
127 | for (j = 0; j < i; j++) | |
128 | __free_page(buf->page_array[j]); | |
129 | kfree(buf->page_array); | |
130 | return NULL; | |
131 | } | |
132 | ||
133 | /** | |
134 | * relay_create_buf - allocate and initialize a channel buffer | |
135 | * @alloc_size: size of the buffer to allocate | |
136 | * @n_subbufs: number of sub-buffers in the channel | |
137 | * | |
138 | * Returns channel buffer if successful, NULL otherwise | |
139 | */ | |
140 | struct rchan_buf *relay_create_buf(struct rchan *chan) | |
141 | { | |
142 | struct rchan_buf *buf = kcalloc(1, sizeof(struct rchan_buf), GFP_KERNEL); | |
143 | if (!buf) | |
144 | return NULL; | |
145 | ||
146 | buf->padding = kmalloc(chan->n_subbufs * sizeof(size_t *), GFP_KERNEL); | |
147 | if (!buf->padding) | |
148 | goto free_buf; | |
149 | ||
221415d7 | 150 | buf->start = relay_alloc_buf(buf, &chan->alloc_size); |
b86ff981 JA |
151 | if (!buf->start) |
152 | goto free_buf; | |
153 | ||
154 | buf->chan = chan; | |
155 | kref_get(&buf->chan->kref); | |
156 | return buf; | |
157 | ||
158 | free_buf: | |
159 | kfree(buf->padding); | |
160 | kfree(buf); | |
161 | return NULL; | |
162 | } | |
163 | ||
164 | /** | |
165 | * relay_destroy_channel - free the channel struct | |
166 | * | |
167 | * Should only be called from kref_put(). | |
168 | */ | |
169 | void relay_destroy_channel(struct kref *kref) | |
170 | { | |
171 | struct rchan *chan = container_of(kref, struct rchan, kref); | |
172 | kfree(chan); | |
173 | } | |
174 | ||
175 | /** | |
176 | * relay_destroy_buf - destroy an rchan_buf struct and associated buffer | |
177 | * @buf: the buffer struct | |
178 | */ | |
179 | void relay_destroy_buf(struct rchan_buf *buf) | |
180 | { | |
181 | struct rchan *chan = buf->chan; | |
182 | unsigned int i; | |
183 | ||
184 | if (likely(buf->start)) { | |
185 | vunmap(buf->start); | |
186 | for (i = 0; i < buf->page_count; i++) | |
187 | __free_page(buf->page_array[i]); | |
188 | kfree(buf->page_array); | |
189 | } | |
190 | kfree(buf->padding); | |
191 | kfree(buf); | |
192 | kref_put(&chan->kref, relay_destroy_channel); | |
193 | } | |
194 | ||
195 | /** | |
196 | * relay_remove_buf - remove a channel buffer | |
197 | * | |
198 | * Removes the file from the fileystem, which also frees the | |
199 | * rchan_buf_struct and the channel buffer. Should only be called from | |
200 | * kref_put(). | |
201 | */ | |
202 | void relay_remove_buf(struct kref *kref) | |
203 | { | |
204 | struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref); | |
205 | buf->chan->cb->remove_buf_file(buf->dentry); | |
206 | relay_destroy_buf(buf); | |
207 | } | |
208 | ||
209 | /** | |
210 | * relay_buf_empty - boolean, is the channel buffer empty? | |
211 | * @buf: channel buffer | |
212 | * | |
213 | * Returns 1 if the buffer is empty, 0 otherwise. | |
214 | */ | |
215 | int relay_buf_empty(struct rchan_buf *buf) | |
216 | { | |
217 | return (buf->subbufs_produced - buf->subbufs_consumed) ? 0 : 1; | |
218 | } | |
219 | EXPORT_SYMBOL_GPL(relay_buf_empty); | |
220 | ||
221 | /** | |
222 | * relay_buf_full - boolean, is the channel buffer full? | |
223 | * @buf: channel buffer | |
224 | * | |
225 | * Returns 1 if the buffer is full, 0 otherwise. | |
226 | */ | |
227 | int relay_buf_full(struct rchan_buf *buf) | |
228 | { | |
229 | size_t ready = buf->subbufs_produced - buf->subbufs_consumed; | |
230 | return (ready >= buf->chan->n_subbufs) ? 1 : 0; | |
231 | } | |
232 | EXPORT_SYMBOL_GPL(relay_buf_full); | |
233 | ||
234 | /* | |
235 | * High-level relay kernel API and associated functions. | |
236 | */ | |
237 | ||
238 | /* | |
239 | * rchan_callback implementations defining default channel behavior. Used | |
240 | * in place of corresponding NULL values in client callback struct. | |
241 | */ | |
242 | ||
243 | /* | |
244 | * subbuf_start() default callback. Does nothing. | |
245 | */ | |
246 | static int subbuf_start_default_callback (struct rchan_buf *buf, | |
247 | void *subbuf, | |
248 | void *prev_subbuf, | |
249 | size_t prev_padding) | |
250 | { | |
251 | if (relay_buf_full(buf)) | |
252 | return 0; | |
253 | ||
254 | return 1; | |
255 | } | |
256 | ||
257 | /* | |
258 | * buf_mapped() default callback. Does nothing. | |
259 | */ | |
260 | static void buf_mapped_default_callback(struct rchan_buf *buf, | |
261 | struct file *filp) | |
262 | { | |
263 | } | |
264 | ||
265 | /* | |
266 | * buf_unmapped() default callback. Does nothing. | |
267 | */ | |
268 | static void buf_unmapped_default_callback(struct rchan_buf *buf, | |
269 | struct file *filp) | |
270 | { | |
271 | } | |
272 | ||
273 | /* | |
274 | * create_buf_file_create() default callback. Does nothing. | |
275 | */ | |
276 | static struct dentry *create_buf_file_default_callback(const char *filename, | |
277 | struct dentry *parent, | |
278 | int mode, | |
279 | struct rchan_buf *buf, | |
280 | int *is_global) | |
281 | { | |
282 | return NULL; | |
283 | } | |
284 | ||
285 | /* | |
286 | * remove_buf_file() default callback. Does nothing. | |
287 | */ | |
288 | static int remove_buf_file_default_callback(struct dentry *dentry) | |
289 | { | |
290 | return -EINVAL; | |
291 | } | |
292 | ||
293 | /* relay channel default callbacks */ | |
294 | static struct rchan_callbacks default_channel_callbacks = { | |
295 | .subbuf_start = subbuf_start_default_callback, | |
296 | .buf_mapped = buf_mapped_default_callback, | |
297 | .buf_unmapped = buf_unmapped_default_callback, | |
298 | .create_buf_file = create_buf_file_default_callback, | |
299 | .remove_buf_file = remove_buf_file_default_callback, | |
300 | }; | |
301 | ||
302 | /** | |
303 | * wakeup_readers - wake up readers waiting on a channel | |
304 | * @private: the channel buffer | |
305 | * | |
306 | * This is the work function used to defer reader waking. The | |
307 | * reason waking is deferred is that calling directly from write | |
308 | * causes problems if you're writing from say the scheduler. | |
309 | */ | |
310 | static void wakeup_readers(void *private) | |
311 | { | |
312 | struct rchan_buf *buf = private; | |
313 | wake_up_interruptible(&buf->read_wait); | |
314 | } | |
315 | ||
316 | /** | |
317 | * __relay_reset - reset a channel buffer | |
318 | * @buf: the channel buffer | |
319 | * @init: 1 if this is a first-time initialization | |
320 | * | |
321 | * See relay_reset for description of effect. | |
322 | */ | |
323 | static inline void __relay_reset(struct rchan_buf *buf, unsigned int init) | |
324 | { | |
325 | size_t i; | |
326 | ||
327 | if (init) { | |
328 | init_waitqueue_head(&buf->read_wait); | |
329 | kref_init(&buf->kref); | |
330 | INIT_WORK(&buf->wake_readers, NULL, NULL); | |
331 | } else { | |
332 | cancel_delayed_work(&buf->wake_readers); | |
333 | flush_scheduled_work(); | |
334 | } | |
335 | ||
336 | buf->subbufs_produced = 0; | |
337 | buf->subbufs_consumed = 0; | |
338 | buf->bytes_consumed = 0; | |
339 | buf->finalized = 0; | |
340 | buf->data = buf->start; | |
341 | buf->offset = 0; | |
342 | ||
343 | for (i = 0; i < buf->chan->n_subbufs; i++) | |
344 | buf->padding[i] = 0; | |
345 | ||
346 | buf->chan->cb->subbuf_start(buf, buf->data, NULL, 0); | |
347 | } | |
348 | ||
349 | /** | |
350 | * relay_reset - reset the channel | |
351 | * @chan: the channel | |
352 | * | |
353 | * This has the effect of erasing all data from all channel buffers | |
354 | * and restarting the channel in its initial state. The buffers | |
355 | * are not freed, so any mappings are still in effect. | |
356 | * | |
357 | * NOTE: Care should be taken that the channel isn't actually | |
358 | * being used by anything when this call is made. | |
359 | */ | |
360 | void relay_reset(struct rchan *chan) | |
361 | { | |
362 | unsigned int i; | |
363 | struct rchan_buf *prev = NULL; | |
364 | ||
365 | if (!chan) | |
366 | return; | |
367 | ||
368 | for (i = 0; i < NR_CPUS; i++) { | |
369 | if (!chan->buf[i] || chan->buf[i] == prev) | |
370 | break; | |
371 | __relay_reset(chan->buf[i], 0); | |
372 | prev = chan->buf[i]; | |
373 | } | |
374 | } | |
375 | EXPORT_SYMBOL_GPL(relay_reset); | |
376 | ||
377 | /** | |
378 | * relay_open_buf - create a new relay channel buffer | |
379 | * | |
380 | * Internal - used by relay_open(). | |
381 | */ | |
382 | static struct rchan_buf *relay_open_buf(struct rchan *chan, | |
383 | const char *filename, | |
384 | struct dentry *parent, | |
385 | int *is_global) | |
386 | { | |
387 | struct rchan_buf *buf; | |
388 | struct dentry *dentry; | |
389 | ||
390 | if (*is_global) | |
391 | return chan->buf[0]; | |
392 | ||
393 | buf = relay_create_buf(chan); | |
394 | if (!buf) | |
395 | return NULL; | |
396 | ||
397 | /* Create file in fs */ | |
398 | dentry = chan->cb->create_buf_file(filename, parent, S_IRUSR, | |
399 | buf, is_global); | |
400 | if (!dentry) { | |
401 | relay_destroy_buf(buf); | |
402 | return NULL; | |
403 | } | |
404 | ||
405 | buf->dentry = dentry; | |
406 | __relay_reset(buf, 1); | |
407 | ||
408 | return buf; | |
409 | } | |
410 | ||
411 | /** | |
412 | * relay_close_buf - close a channel buffer | |
413 | * @buf: channel buffer | |
414 | * | |
415 | * Marks the buffer finalized and restores the default callbacks. | |
416 | * The channel buffer and channel buffer data structure are then freed | |
417 | * automatically when the last reference is given up. | |
418 | */ | |
419 | static inline void relay_close_buf(struct rchan_buf *buf) | |
420 | { | |
421 | buf->finalized = 1; | |
422 | cancel_delayed_work(&buf->wake_readers); | |
423 | flush_scheduled_work(); | |
424 | kref_put(&buf->kref, relay_remove_buf); | |
425 | } | |
426 | ||
427 | static inline void setup_callbacks(struct rchan *chan, | |
428 | struct rchan_callbacks *cb) | |
429 | { | |
430 | if (!cb) { | |
431 | chan->cb = &default_channel_callbacks; | |
432 | return; | |
433 | } | |
434 | ||
435 | if (!cb->subbuf_start) | |
436 | cb->subbuf_start = subbuf_start_default_callback; | |
437 | if (!cb->buf_mapped) | |
438 | cb->buf_mapped = buf_mapped_default_callback; | |
439 | if (!cb->buf_unmapped) | |
440 | cb->buf_unmapped = buf_unmapped_default_callback; | |
441 | if (!cb->create_buf_file) | |
442 | cb->create_buf_file = create_buf_file_default_callback; | |
443 | if (!cb->remove_buf_file) | |
444 | cb->remove_buf_file = remove_buf_file_default_callback; | |
445 | chan->cb = cb; | |
446 | } | |
447 | ||
448 | /** | |
449 | * relay_open - create a new relay channel | |
450 | * @base_filename: base name of files to create | |
451 | * @parent: dentry of parent directory, NULL for root directory | |
452 | * @subbuf_size: size of sub-buffers | |
453 | * @n_subbufs: number of sub-buffers | |
454 | * @cb: client callback functions | |
455 | * | |
456 | * Returns channel pointer if successful, NULL otherwise. | |
457 | * | |
458 | * Creates a channel buffer for each cpu using the sizes and | |
459 | * attributes specified. The created channel buffer files | |
460 | * will be named base_filename0...base_filenameN-1. File | |
461 | * permissions will be S_IRUSR. | |
462 | */ | |
463 | struct rchan *relay_open(const char *base_filename, | |
464 | struct dentry *parent, | |
465 | size_t subbuf_size, | |
466 | size_t n_subbufs, | |
467 | struct rchan_callbacks *cb) | |
468 | { | |
469 | unsigned int i; | |
470 | struct rchan *chan; | |
471 | char *tmpname; | |
472 | int is_global = 0; | |
473 | ||
474 | if (!base_filename) | |
475 | return NULL; | |
476 | ||
477 | if (!(subbuf_size && n_subbufs)) | |
478 | return NULL; | |
479 | ||
480 | chan = kcalloc(1, sizeof(struct rchan), GFP_KERNEL); | |
481 | if (!chan) | |
482 | return NULL; | |
483 | ||
484 | chan->version = RELAYFS_CHANNEL_VERSION; | |
485 | chan->n_subbufs = n_subbufs; | |
486 | chan->subbuf_size = subbuf_size; | |
487 | chan->alloc_size = FIX_SIZE(subbuf_size * n_subbufs); | |
488 | setup_callbacks(chan, cb); | |
489 | kref_init(&chan->kref); | |
490 | ||
491 | tmpname = kmalloc(NAME_MAX + 1, GFP_KERNEL); | |
492 | if (!tmpname) | |
493 | goto free_chan; | |
494 | ||
495 | for_each_online_cpu(i) { | |
496 | sprintf(tmpname, "%s%d", base_filename, i); | |
497 | chan->buf[i] = relay_open_buf(chan, tmpname, parent, | |
498 | &is_global); | |
499 | if (!chan->buf[i]) | |
500 | goto free_bufs; | |
501 | ||
502 | chan->buf[i]->cpu = i; | |
503 | } | |
504 | ||
505 | kfree(tmpname); | |
506 | return chan; | |
507 | ||
508 | free_bufs: | |
509 | for (i = 0; i < NR_CPUS; i++) { | |
510 | if (!chan->buf[i]) | |
511 | break; | |
512 | relay_close_buf(chan->buf[i]); | |
513 | if (is_global) | |
514 | break; | |
515 | } | |
516 | kfree(tmpname); | |
517 | ||
518 | free_chan: | |
519 | kref_put(&chan->kref, relay_destroy_channel); | |
520 | return NULL; | |
521 | } | |
522 | EXPORT_SYMBOL_GPL(relay_open); | |
523 | ||
524 | /** | |
525 | * relay_switch_subbuf - switch to a new sub-buffer | |
526 | * @buf: channel buffer | |
527 | * @length: size of current event | |
528 | * | |
529 | * Returns either the length passed in or 0 if full. | |
530 | * | |
531 | * Performs sub-buffer-switch tasks such as invoking callbacks, | |
532 | * updating padding counts, waking up readers, etc. | |
533 | */ | |
534 | size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length) | |
535 | { | |
536 | void *old, *new; | |
537 | size_t old_subbuf, new_subbuf; | |
538 | ||
539 | if (unlikely(length > buf->chan->subbuf_size)) | |
540 | goto toobig; | |
541 | ||
542 | if (buf->offset != buf->chan->subbuf_size + 1) { | |
543 | buf->prev_padding = buf->chan->subbuf_size - buf->offset; | |
544 | old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; | |
545 | buf->padding[old_subbuf] = buf->prev_padding; | |
546 | buf->subbufs_produced++; | |
221415d7 JA |
547 | buf->dentry->d_inode->i_size += buf->chan->subbuf_size - |
548 | buf->padding[old_subbuf]; | |
549 | smp_mb(); | |
b86ff981 JA |
550 | if (waitqueue_active(&buf->read_wait)) { |
551 | PREPARE_WORK(&buf->wake_readers, wakeup_readers, buf); | |
552 | schedule_delayed_work(&buf->wake_readers, 1); | |
553 | } | |
554 | } | |
555 | ||
556 | old = buf->data; | |
557 | new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; | |
558 | new = buf->start + new_subbuf * buf->chan->subbuf_size; | |
559 | buf->offset = 0; | |
560 | if (!buf->chan->cb->subbuf_start(buf, new, old, buf->prev_padding)) { | |
561 | buf->offset = buf->chan->subbuf_size + 1; | |
562 | return 0; | |
563 | } | |
564 | buf->data = new; | |
565 | buf->padding[new_subbuf] = 0; | |
566 | ||
567 | if (unlikely(length + buf->offset > buf->chan->subbuf_size)) | |
568 | goto toobig; | |
569 | ||
570 | return length; | |
571 | ||
572 | toobig: | |
573 | buf->chan->last_toobig = length; | |
574 | return 0; | |
575 | } | |
576 | EXPORT_SYMBOL_GPL(relay_switch_subbuf); | |
577 | ||
578 | /** | |
579 | * relay_subbufs_consumed - update the buffer's sub-buffers-consumed count | |
580 | * @chan: the channel | |
581 | * @cpu: the cpu associated with the channel buffer to update | |
582 | * @subbufs_consumed: number of sub-buffers to add to current buf's count | |
583 | * | |
584 | * Adds to the channel buffer's consumed sub-buffer count. | |
585 | * subbufs_consumed should be the number of sub-buffers newly consumed, | |
586 | * not the total consumed. | |
587 | * | |
588 | * NOTE: kernel clients don't need to call this function if the channel | |
589 | * mode is 'overwrite'. | |
590 | */ | |
591 | void relay_subbufs_consumed(struct rchan *chan, | |
592 | unsigned int cpu, | |
593 | size_t subbufs_consumed) | |
594 | { | |
595 | struct rchan_buf *buf; | |
596 | ||
597 | if (!chan) | |
598 | return; | |
599 | ||
600 | if (cpu >= NR_CPUS || !chan->buf[cpu]) | |
601 | return; | |
602 | ||
603 | buf = chan->buf[cpu]; | |
604 | buf->subbufs_consumed += subbufs_consumed; | |
605 | if (buf->subbufs_consumed > buf->subbufs_produced) | |
606 | buf->subbufs_consumed = buf->subbufs_produced; | |
607 | } | |
608 | EXPORT_SYMBOL_GPL(relay_subbufs_consumed); | |
609 | ||
610 | /** | |
611 | * relay_close - close the channel | |
612 | * @chan: the channel | |
613 | * | |
614 | * Closes all channel buffers and frees the channel. | |
615 | */ | |
616 | void relay_close(struct rchan *chan) | |
617 | { | |
618 | unsigned int i; | |
619 | struct rchan_buf *prev = NULL; | |
620 | ||
621 | if (!chan) | |
622 | return; | |
623 | ||
624 | for (i = 0; i < NR_CPUS; i++) { | |
625 | if (!chan->buf[i] || chan->buf[i] == prev) | |
626 | break; | |
627 | relay_close_buf(chan->buf[i]); | |
628 | prev = chan->buf[i]; | |
629 | } | |
630 | ||
631 | if (chan->last_toobig) | |
632 | printk(KERN_WARNING "relay: one or more items not logged " | |
633 | "[item size (%Zd) > sub-buffer size (%Zd)]\n", | |
634 | chan->last_toobig, chan->subbuf_size); | |
635 | ||
636 | kref_put(&chan->kref, relay_destroy_channel); | |
637 | } | |
638 | EXPORT_SYMBOL_GPL(relay_close); | |
639 | ||
640 | /** | |
641 | * relay_flush - close the channel | |
642 | * @chan: the channel | |
643 | * | |
644 | * Flushes all channel buffers i.e. forces buffer switch. | |
645 | */ | |
646 | void relay_flush(struct rchan *chan) | |
647 | { | |
648 | unsigned int i; | |
649 | struct rchan_buf *prev = NULL; | |
650 | ||
651 | if (!chan) | |
652 | return; | |
653 | ||
654 | for (i = 0; i < NR_CPUS; i++) { | |
655 | if (!chan->buf[i] || chan->buf[i] == prev) | |
656 | break; | |
657 | relay_switch_subbuf(chan->buf[i], 0); | |
658 | prev = chan->buf[i]; | |
659 | } | |
660 | } | |
661 | EXPORT_SYMBOL_GPL(relay_flush); | |
662 | ||
663 | /** | |
664 | * relay_file_open - open file op for relay files | |
665 | * @inode: the inode | |
666 | * @filp: the file | |
667 | * | |
668 | * Increments the channel buffer refcount. | |
669 | */ | |
670 | static int relay_file_open(struct inode *inode, struct file *filp) | |
671 | { | |
672 | struct rchan_buf *buf = inode->u.generic_ip; | |
673 | kref_get(&buf->kref); | |
674 | filp->private_data = buf; | |
675 | ||
676 | return 0; | |
677 | } | |
678 | ||
679 | /** | |
680 | * relay_file_mmap - mmap file op for relay files | |
681 | * @filp: the file | |
682 | * @vma: the vma describing what to map | |
683 | * | |
684 | * Calls upon relay_mmap_buf to map the file into user space. | |
685 | */ | |
686 | static int relay_file_mmap(struct file *filp, struct vm_area_struct *vma) | |
687 | { | |
688 | struct rchan_buf *buf = filp->private_data; | |
689 | return relay_mmap_buf(buf, vma); | |
690 | } | |
691 | ||
692 | /** | |
693 | * relay_file_poll - poll file op for relay files | |
694 | * @filp: the file | |
695 | * @wait: poll table | |
696 | * | |
697 | * Poll implemention. | |
698 | */ | |
699 | static unsigned int relay_file_poll(struct file *filp, poll_table *wait) | |
700 | { | |
701 | unsigned int mask = 0; | |
702 | struct rchan_buf *buf = filp->private_data; | |
703 | ||
704 | if (buf->finalized) | |
705 | return POLLERR; | |
706 | ||
707 | if (filp->f_mode & FMODE_READ) { | |
708 | poll_wait(filp, &buf->read_wait, wait); | |
709 | if (!relay_buf_empty(buf)) | |
710 | mask |= POLLIN | POLLRDNORM; | |
711 | } | |
712 | ||
713 | return mask; | |
714 | } | |
715 | ||
716 | /** | |
717 | * relay_file_release - release file op for relay files | |
718 | * @inode: the inode | |
719 | * @filp: the file | |
720 | * | |
721 | * Decrements the channel refcount, as the filesystem is | |
722 | * no longer using it. | |
723 | */ | |
724 | static int relay_file_release(struct inode *inode, struct file *filp) | |
725 | { | |
726 | struct rchan_buf *buf = filp->private_data; | |
727 | kref_put(&buf->kref, relay_remove_buf); | |
728 | ||
729 | return 0; | |
730 | } | |
731 | ||
732 | /** | |
733 | * relay_file_read_consume - update the consumed count for the buffer | |
734 | */ | |
735 | static void relay_file_read_consume(struct rchan_buf *buf, | |
736 | size_t read_pos, | |
737 | size_t bytes_consumed) | |
738 | { | |
739 | size_t subbuf_size = buf->chan->subbuf_size; | |
740 | size_t n_subbufs = buf->chan->n_subbufs; | |
741 | size_t read_subbuf; | |
742 | ||
743 | if (buf->bytes_consumed + bytes_consumed > subbuf_size) { | |
744 | relay_subbufs_consumed(buf->chan, buf->cpu, 1); | |
745 | buf->bytes_consumed = 0; | |
746 | } | |
747 | ||
748 | buf->bytes_consumed += bytes_consumed; | |
749 | read_subbuf = read_pos / buf->chan->subbuf_size; | |
750 | if (buf->bytes_consumed + buf->padding[read_subbuf] == subbuf_size) { | |
751 | if ((read_subbuf == buf->subbufs_produced % n_subbufs) && | |
752 | (buf->offset == subbuf_size)) | |
753 | return; | |
754 | relay_subbufs_consumed(buf->chan, buf->cpu, 1); | |
755 | buf->bytes_consumed = 0; | |
756 | } | |
757 | } | |
758 | ||
759 | /** | |
760 | * relay_file_read_avail - boolean, are there unconsumed bytes available? | |
761 | */ | |
762 | static int relay_file_read_avail(struct rchan_buf *buf, size_t read_pos) | |
763 | { | |
b86ff981 JA |
764 | size_t subbuf_size = buf->chan->subbuf_size; |
765 | size_t n_subbufs = buf->chan->n_subbufs; | |
221415d7 JA |
766 | size_t produced = buf->subbufs_produced; |
767 | size_t consumed = buf->subbufs_consumed; | |
b86ff981 | 768 | |
221415d7 | 769 | relay_file_read_consume(buf, read_pos, 0); |
b86ff981 | 770 | |
221415d7 JA |
771 | if (unlikely(buf->offset > subbuf_size)) { |
772 | if (produced == consumed) | |
773 | return 0; | |
774 | return 1; | |
b86ff981 JA |
775 | } |
776 | ||
221415d7 JA |
777 | if (unlikely(produced - consumed >= n_subbufs)) { |
778 | consumed = (produced / n_subbufs) * n_subbufs; | |
779 | buf->subbufs_consumed = consumed; | |
780 | } | |
781 | ||
782 | produced = (produced % n_subbufs) * subbuf_size + buf->offset; | |
783 | consumed = (consumed % n_subbufs) * subbuf_size + buf->bytes_consumed; | |
784 | ||
785 | if (consumed > produced) | |
786 | produced += n_subbufs * subbuf_size; | |
787 | ||
788 | if (consumed == produced) | |
b86ff981 JA |
789 | return 0; |
790 | ||
b86ff981 JA |
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 | ||
221415d7 JA |
911 | static ssize_t relay_file_sendsubbuf(struct file *filp, loff_t *ppos, |
912 | size_t count, read_actor_t actor, | |
913 | void *target) | |
914 | { | |
915 | struct rchan_buf *buf = filp->private_data; | |
916 | read_descriptor_t desc; | |
917 | size_t read_start, avail; | |
918 | unsigned long pidx, poff; | |
919 | unsigned int subbuf_pages; | |
920 | ssize_t ret = 0; | |
921 | ||
922 | if (!relay_file_read_avail(buf, *ppos)) | |
923 | return 0; | |
924 | ||
925 | read_start = relay_file_read_start_pos(*ppos, buf); | |
926 | avail = relay_file_read_subbuf_avail(read_start, buf); | |
927 | if (!avail) | |
928 | return 0; | |
929 | ||
930 | count = min(count, avail); | |
931 | ||
932 | desc.written = 0; | |
933 | desc.count = count; | |
934 | desc.arg.data = target; | |
935 | desc.error = 0; | |
936 | ||
937 | subbuf_pages = buf->chan->alloc_size >> PAGE_SHIFT; | |
938 | pidx = (read_start / PAGE_SIZE) % subbuf_pages; | |
939 | poff = read_start & ~PAGE_MASK; | |
940 | while (count) { | |
941 | struct page *p = buf->page_array[pidx]; | |
942 | unsigned int len; | |
943 | ||
944 | len = PAGE_SIZE - poff; | |
945 | if (len > count) | |
946 | len = count; | |
947 | ||
948 | len = actor(&desc, p, poff, len); | |
949 | ||
950 | if (desc.error) { | |
951 | if (!ret) | |
952 | ret = desc.error; | |
953 | break; | |
954 | } | |
955 | ||
956 | count -= len; | |
957 | ret += len; | |
958 | poff = 0; | |
959 | pidx = (pidx + 1) % subbuf_pages; | |
960 | } | |
961 | ||
962 | if (ret > 0) { | |
963 | relay_file_read_consume(buf, read_start, ret); | |
964 | *ppos = relay_file_read_end_pos(buf, read_start, ret); | |
965 | } | |
966 | ||
967 | return ret; | |
968 | } | |
969 | ||
970 | static ssize_t relay_file_sendfile(struct file *filp, loff_t *ppos, | |
971 | size_t count, read_actor_t actor, | |
972 | void *target) | |
973 | { | |
974 | ssize_t sent = 0, ret = 0; | |
975 | ||
976 | if (!count) | |
977 | return 0; | |
978 | ||
979 | mutex_lock(&filp->f_dentry->d_inode->i_mutex); | |
980 | ||
981 | do { | |
982 | ret = relay_file_sendsubbuf(filp, ppos, count, actor, target); | |
983 | if (ret < 0) { | |
984 | if (!sent) | |
985 | sent = ret; | |
986 | break; | |
987 | } | |
988 | count -= ret; | |
989 | sent += ret; | |
990 | } while (count && ret); | |
991 | ||
992 | mutex_unlock(&filp->f_dentry->d_inode->i_mutex); | |
993 | return sent; | |
994 | } | |
995 | ||
b86ff981 JA |
996 | struct file_operations relay_file_operations = { |
997 | .open = relay_file_open, | |
998 | .poll = relay_file_poll, | |
999 | .mmap = relay_file_mmap, | |
1000 | .read = relay_file_read, | |
1001 | .llseek = no_llseek, | |
1002 | .release = relay_file_release, | |
221415d7 | 1003 | .sendfile = relay_file_sendfile, |
b86ff981 JA |
1004 | }; |
1005 | EXPORT_SYMBOL_GPL(relay_file_operations); |