Commit | Line | Data |
---|---|---|
b86ff981 JA |
1 | /* |
2 | * Public API and common code for kernel->userspace relay file support. | |
3 | * | |
c9b3febc | 4 | * See Documentation/filesystems/relay.txt for an overview. |
b86ff981 JA |
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. | |
23c88752 MD |
10 | * November 2006 - CPU hotplug support by Mathieu Desnoyers |
11 | * (mathieu.desnoyers@polymtl.ca) | |
b86ff981 JA |
12 | * |
13 | * This file is released under the GPL. | |
14 | */ | |
15 | #include <linux/errno.h> | |
16 | #include <linux/stddef.h> | |
17 | #include <linux/slab.h> | |
9984de1a | 18 | #include <linux/export.h> |
b86ff981 JA |
19 | #include <linux/string.h> |
20 | #include <linux/relay.h> | |
21 | #include <linux/vmalloc.h> | |
22 | #include <linux/mm.h> | |
23c88752 | 23 | #include <linux/cpu.h> |
d6b29d7c | 24 | #include <linux/splice.h> |
23c88752 MD |
25 | |
26 | /* list of open channels, for cpu hotplug */ | |
27 | static DEFINE_MUTEX(relay_channels_mutex); | |
28 | static LIST_HEAD(relay_channels); | |
b86ff981 JA |
29 | |
30 | /* | |
31 | * close() vm_op implementation for relay file mapping. | |
32 | */ | |
33 | static void relay_file_mmap_close(struct vm_area_struct *vma) | |
34 | { | |
35 | struct rchan_buf *buf = vma->vm_private_data; | |
36 | buf->chan->cb->buf_unmapped(buf, vma->vm_file); | |
37 | } | |
38 | ||
39 | /* | |
a1e09612 | 40 | * fault() vm_op implementation for relay file mapping. |
b86ff981 | 41 | */ |
a1e09612 | 42 | static int relay_buf_fault(struct vm_area_struct *vma, struct vm_fault *vmf) |
b86ff981 JA |
43 | { |
44 | struct page *page; | |
45 | struct rchan_buf *buf = vma->vm_private_data; | |
a1e09612 | 46 | pgoff_t pgoff = vmf->pgoff; |
b86ff981 | 47 | |
b86ff981 | 48 | if (!buf) |
a1e09612 | 49 | return VM_FAULT_OOM; |
b86ff981 | 50 | |
a1e09612 | 51 | page = vmalloc_to_page(buf->start + (pgoff << PAGE_SHIFT)); |
b86ff981 | 52 | if (!page) |
a1e09612 | 53 | return VM_FAULT_SIGBUS; |
b86ff981 | 54 | get_page(page); |
a1e09612 | 55 | vmf->page = page; |
b86ff981 | 56 | |
a1e09612 | 57 | return 0; |
b86ff981 JA |
58 | } |
59 | ||
60 | /* | |
61 | * vm_ops for relay file mappings. | |
62 | */ | |
f0f37e2f | 63 | static const struct vm_operations_struct relay_file_mmap_ops = { |
a1e09612 | 64 | .fault = relay_buf_fault, |
b86ff981 JA |
65 | .close = relay_file_mmap_close, |
66 | }; | |
67 | ||
68ab3d88 MH |
68 | /* |
69 | * allocate an array of pointers of struct page | |
70 | */ | |
71 | static struct page **relay_alloc_page_array(unsigned int n_pages) | |
72 | { | |
408af87a JJ |
73 | const size_t pa_size = n_pages * sizeof(struct page *); |
74 | if (pa_size > PAGE_SIZE) | |
75 | return vzalloc(pa_size); | |
76 | return kzalloc(pa_size, GFP_KERNEL); | |
68ab3d88 MH |
77 | } |
78 | ||
79 | /* | |
80 | * free an array of pointers of struct page | |
81 | */ | |
82 | static void relay_free_page_array(struct page **array) | |
83 | { | |
200f1ce3 | 84 | kvfree(array); |
68ab3d88 MH |
85 | } |
86 | ||
b86ff981 JA |
87 | /** |
88 | * relay_mmap_buf: - mmap channel buffer to process address space | |
89 | * @buf: relay channel buffer | |
90 | * @vma: vm_area_struct describing memory to be mapped | |
91 | * | |
92 | * Returns 0 if ok, negative on error | |
93 | * | |
94 | * Caller should already have grabbed mmap_sem. | |
95 | */ | |
01c55ed3 | 96 | static int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma) |
b86ff981 JA |
97 | { |
98 | unsigned long length = vma->vm_end - vma->vm_start; | |
99 | struct file *filp = vma->vm_file; | |
100 | ||
101 | if (!buf) | |
102 | return -EBADF; | |
103 | ||
104 | if (length != (unsigned long)buf->chan->alloc_size) | |
105 | return -EINVAL; | |
106 | ||
107 | vma->vm_ops = &relay_file_mmap_ops; | |
2f98735c | 108 | vma->vm_flags |= VM_DONTEXPAND; |
b86ff981 JA |
109 | vma->vm_private_data = buf; |
110 | buf->chan->cb->buf_mapped(buf, filp); | |
111 | ||
112 | return 0; | |
113 | } | |
114 | ||
115 | /** | |
116 | * relay_alloc_buf - allocate a channel buffer | |
117 | * @buf: the buffer struct | |
118 | * @size: total size of the buffer | |
119 | * | |
4c78a663 | 120 | * Returns a pointer to the resulting buffer, %NULL if unsuccessful. The |
221415d7 | 121 | * passed in size will get page aligned, if it isn't already. |
b86ff981 | 122 | */ |
221415d7 | 123 | static void *relay_alloc_buf(struct rchan_buf *buf, size_t *size) |
b86ff981 JA |
124 | { |
125 | void *mem; | |
126 | unsigned int i, j, n_pages; | |
127 | ||
221415d7 JA |
128 | *size = PAGE_ALIGN(*size); |
129 | n_pages = *size >> PAGE_SHIFT; | |
b86ff981 | 130 | |
68ab3d88 | 131 | buf->page_array = relay_alloc_page_array(n_pages); |
b86ff981 JA |
132 | if (!buf->page_array) |
133 | return NULL; | |
134 | ||
135 | for (i = 0; i < n_pages; i++) { | |
136 | buf->page_array[i] = alloc_page(GFP_KERNEL); | |
137 | if (unlikely(!buf->page_array[i])) | |
138 | goto depopulate; | |
ebf99093 | 139 | set_page_private(buf->page_array[i], (unsigned long)buf); |
b86ff981 JA |
140 | } |
141 | mem = vmap(buf->page_array, n_pages, VM_MAP, PAGE_KERNEL); | |
142 | if (!mem) | |
143 | goto depopulate; | |
144 | ||
221415d7 | 145 | memset(mem, 0, *size); |
b86ff981 JA |
146 | buf->page_count = n_pages; |
147 | return mem; | |
148 | ||
149 | depopulate: | |
150 | for (j = 0; j < i; j++) | |
151 | __free_page(buf->page_array[j]); | |
68ab3d88 | 152 | relay_free_page_array(buf->page_array); |
b86ff981 JA |
153 | return NULL; |
154 | } | |
155 | ||
156 | /** | |
157 | * relay_create_buf - allocate and initialize a channel buffer | |
4c78a663 | 158 | * @chan: the relay channel |
b86ff981 | 159 | * |
4c78a663 | 160 | * Returns channel buffer if successful, %NULL otherwise. |
b86ff981 | 161 | */ |
01c55ed3 | 162 | static struct rchan_buf *relay_create_buf(struct rchan *chan) |
b86ff981 | 163 | { |
f6302f1b DC |
164 | struct rchan_buf *buf; |
165 | ||
166 | if (chan->n_subbufs > UINT_MAX / sizeof(size_t *)) | |
b86ff981 JA |
167 | return NULL; |
168 | ||
f6302f1b DC |
169 | buf = kzalloc(sizeof(struct rchan_buf), GFP_KERNEL); |
170 | if (!buf) | |
171 | return NULL; | |
b86ff981 JA |
172 | buf->padding = kmalloc(chan->n_subbufs * sizeof(size_t *), GFP_KERNEL); |
173 | if (!buf->padding) | |
174 | goto free_buf; | |
175 | ||
221415d7 | 176 | buf->start = relay_alloc_buf(buf, &chan->alloc_size); |
b86ff981 JA |
177 | if (!buf->start) |
178 | goto free_buf; | |
179 | ||
180 | buf->chan = chan; | |
181 | kref_get(&buf->chan->kref); | |
182 | return buf; | |
183 | ||
184 | free_buf: | |
185 | kfree(buf->padding); | |
186 | kfree(buf); | |
187 | return NULL; | |
188 | } | |
189 | ||
190 | /** | |
191 | * relay_destroy_channel - free the channel struct | |
4c78a663 | 192 | * @kref: target kernel reference that contains the relay channel |
b86ff981 JA |
193 | * |
194 | * Should only be called from kref_put(). | |
195 | */ | |
01c55ed3 | 196 | static void relay_destroy_channel(struct kref *kref) |
b86ff981 JA |
197 | { |
198 | struct rchan *chan = container_of(kref, struct rchan, kref); | |
199 | kfree(chan); | |
200 | } | |
201 | ||
202 | /** | |
203 | * relay_destroy_buf - destroy an rchan_buf struct and associated buffer | |
204 | * @buf: the buffer struct | |
205 | */ | |
01c55ed3 | 206 | static void relay_destroy_buf(struct rchan_buf *buf) |
b86ff981 JA |
207 | { |
208 | struct rchan *chan = buf->chan; | |
209 | unsigned int i; | |
210 | ||
211 | if (likely(buf->start)) { | |
212 | vunmap(buf->start); | |
213 | for (i = 0; i < buf->page_count; i++) | |
214 | __free_page(buf->page_array[i]); | |
68ab3d88 | 215 | relay_free_page_array(buf->page_array); |
b86ff981 | 216 | } |
23c88752 | 217 | chan->buf[buf->cpu] = NULL; |
b86ff981 JA |
218 | kfree(buf->padding); |
219 | kfree(buf); | |
220 | kref_put(&chan->kref, relay_destroy_channel); | |
221 | } | |
222 | ||
223 | /** | |
224 | * relay_remove_buf - remove a channel buffer | |
4c78a663 | 225 | * @kref: target kernel reference that contains the relay buffer |
b86ff981 | 226 | * |
e227867f | 227 | * Removes the file from the filesystem, which also frees the |
b86ff981 JA |
228 | * rchan_buf_struct and the channel buffer. Should only be called from |
229 | * kref_put(). | |
230 | */ | |
01c55ed3 | 231 | static void relay_remove_buf(struct kref *kref) |
b86ff981 JA |
232 | { |
233 | struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref); | |
b86ff981 JA |
234 | relay_destroy_buf(buf); |
235 | } | |
236 | ||
237 | /** | |
238 | * relay_buf_empty - boolean, is the channel buffer empty? | |
239 | * @buf: channel buffer | |
240 | * | |
241 | * Returns 1 if the buffer is empty, 0 otherwise. | |
242 | */ | |
01c55ed3 | 243 | static int relay_buf_empty(struct rchan_buf *buf) |
b86ff981 JA |
244 | { |
245 | return (buf->subbufs_produced - buf->subbufs_consumed) ? 0 : 1; | |
246 | } | |
b86ff981 JA |
247 | |
248 | /** | |
249 | * relay_buf_full - boolean, is the channel buffer full? | |
250 | * @buf: channel buffer | |
251 | * | |
252 | * Returns 1 if the buffer is full, 0 otherwise. | |
253 | */ | |
254 | int relay_buf_full(struct rchan_buf *buf) | |
255 | { | |
256 | size_t ready = buf->subbufs_produced - buf->subbufs_consumed; | |
257 | return (ready >= buf->chan->n_subbufs) ? 1 : 0; | |
258 | } | |
259 | EXPORT_SYMBOL_GPL(relay_buf_full); | |
260 | ||
261 | /* | |
262 | * High-level relay kernel API and associated functions. | |
263 | */ | |
264 | ||
265 | /* | |
266 | * rchan_callback implementations defining default channel behavior. Used | |
267 | * in place of corresponding NULL values in client callback struct. | |
268 | */ | |
269 | ||
270 | /* | |
271 | * subbuf_start() default callback. Does nothing. | |
272 | */ | |
273 | static int subbuf_start_default_callback (struct rchan_buf *buf, | |
274 | void *subbuf, | |
275 | void *prev_subbuf, | |
276 | size_t prev_padding) | |
277 | { | |
278 | if (relay_buf_full(buf)) | |
279 | return 0; | |
280 | ||
281 | return 1; | |
282 | } | |
283 | ||
284 | /* | |
285 | * buf_mapped() default callback. Does nothing. | |
286 | */ | |
287 | static void buf_mapped_default_callback(struct rchan_buf *buf, | |
288 | struct file *filp) | |
289 | { | |
290 | } | |
291 | ||
292 | /* | |
293 | * buf_unmapped() default callback. Does nothing. | |
294 | */ | |
295 | static void buf_unmapped_default_callback(struct rchan_buf *buf, | |
296 | struct file *filp) | |
297 | { | |
298 | } | |
299 | ||
300 | /* | |
301 | * create_buf_file_create() default callback. Does nothing. | |
302 | */ | |
303 | static struct dentry *create_buf_file_default_callback(const char *filename, | |
304 | struct dentry *parent, | |
f4ae40a6 | 305 | umode_t mode, |
b86ff981 JA |
306 | struct rchan_buf *buf, |
307 | int *is_global) | |
308 | { | |
309 | return NULL; | |
310 | } | |
311 | ||
312 | /* | |
313 | * remove_buf_file() default callback. Does nothing. | |
314 | */ | |
315 | static int remove_buf_file_default_callback(struct dentry *dentry) | |
316 | { | |
317 | return -EINVAL; | |
318 | } | |
319 | ||
320 | /* relay channel default callbacks */ | |
321 | static struct rchan_callbacks default_channel_callbacks = { | |
322 | .subbuf_start = subbuf_start_default_callback, | |
323 | .buf_mapped = buf_mapped_default_callback, | |
324 | .buf_unmapped = buf_unmapped_default_callback, | |
325 | .create_buf_file = create_buf_file_default_callback, | |
326 | .remove_buf_file = remove_buf_file_default_callback, | |
327 | }; | |
328 | ||
329 | /** | |
330 | * wakeup_readers - wake up readers waiting on a channel | |
9a9136e2 | 331 | * @data: contains the channel buffer |
b86ff981 | 332 | * |
7c9cb383 | 333 | * This is the timer function used to defer reader waking. |
b86ff981 | 334 | */ |
7c9cb383 | 335 | static void wakeup_readers(unsigned long data) |
b86ff981 | 336 | { |
7c9cb383 | 337 | struct rchan_buf *buf = (struct rchan_buf *)data; |
b86ff981 JA |
338 | wake_up_interruptible(&buf->read_wait); |
339 | } | |
340 | ||
341 | /** | |
342 | * __relay_reset - reset a channel buffer | |
343 | * @buf: the channel buffer | |
344 | * @init: 1 if this is a first-time initialization | |
345 | * | |
72fd4a35 | 346 | * See relay_reset() for description of effect. |
b86ff981 | 347 | */ |
192636ad | 348 | static void __relay_reset(struct rchan_buf *buf, unsigned int init) |
b86ff981 JA |
349 | { |
350 | size_t i; | |
351 | ||
352 | if (init) { | |
353 | init_waitqueue_head(&buf->read_wait); | |
354 | kref_init(&buf->kref); | |
7c9cb383 TZ |
355 | setup_timer(&buf->timer, wakeup_readers, (unsigned long)buf); |
356 | } else | |
357 | del_timer_sync(&buf->timer); | |
b86ff981 JA |
358 | |
359 | buf->subbufs_produced = 0; | |
360 | buf->subbufs_consumed = 0; | |
361 | buf->bytes_consumed = 0; | |
362 | buf->finalized = 0; | |
363 | buf->data = buf->start; | |
364 | buf->offset = 0; | |
365 | ||
366 | for (i = 0; i < buf->chan->n_subbufs; i++) | |
367 | buf->padding[i] = 0; | |
368 | ||
369 | buf->chan->cb->subbuf_start(buf, buf->data, NULL, 0); | |
370 | } | |
371 | ||
372 | /** | |
373 | * relay_reset - reset the channel | |
374 | * @chan: the channel | |
375 | * | |
376 | * This has the effect of erasing all data from all channel buffers | |
377 | * and restarting the channel in its initial state. The buffers | |
378 | * are not freed, so any mappings are still in effect. | |
379 | * | |
72fd4a35 | 380 | * NOTE. Care should be taken that the channel isn't actually |
b86ff981 JA |
381 | * being used by anything when this call is made. |
382 | */ | |
383 | void relay_reset(struct rchan *chan) | |
384 | { | |
385 | unsigned int i; | |
b86ff981 JA |
386 | |
387 | if (!chan) | |
388 | return; | |
389 | ||
1bfbc608 | 390 | if (chan->is_global && chan->buf[0]) { |
23c88752 MD |
391 | __relay_reset(chan->buf[0], 0); |
392 | return; | |
b86ff981 | 393 | } |
23c88752 MD |
394 | |
395 | mutex_lock(&relay_channels_mutex); | |
98ba4031 | 396 | for_each_possible_cpu(i) |
23c88752 MD |
397 | if (chan->buf[i]) |
398 | __relay_reset(chan->buf[i], 0); | |
399 | mutex_unlock(&relay_channels_mutex); | |
b86ff981 JA |
400 | } |
401 | EXPORT_SYMBOL_GPL(relay_reset); | |
402 | ||
20d8b67c EGM |
403 | static inline void relay_set_buf_dentry(struct rchan_buf *buf, |
404 | struct dentry *dentry) | |
405 | { | |
406 | buf->dentry = dentry; | |
7682c918 | 407 | d_inode(buf->dentry)->i_size = buf->early_bytes; |
20d8b67c EGM |
408 | } |
409 | ||
410 | static struct dentry *relay_create_buf_file(struct rchan *chan, | |
411 | struct rchan_buf *buf, | |
412 | unsigned int cpu) | |
413 | { | |
414 | struct dentry *dentry; | |
415 | char *tmpname; | |
416 | ||
417 | tmpname = kzalloc(NAME_MAX + 1, GFP_KERNEL); | |
418 | if (!tmpname) | |
419 | return NULL; | |
420 | snprintf(tmpname, NAME_MAX, "%s%d", chan->base_filename, cpu); | |
421 | ||
422 | /* Create file in fs */ | |
423 | dentry = chan->cb->create_buf_file(tmpname, chan->parent, | |
424 | S_IRUSR, buf, | |
425 | &chan->is_global); | |
426 | ||
427 | kfree(tmpname); | |
428 | ||
429 | return dentry; | |
430 | } | |
431 | ||
4c78a663 | 432 | /* |
b86ff981 JA |
433 | * relay_open_buf - create a new relay channel buffer |
434 | * | |
23c88752 | 435 | * used by relay_open() and CPU hotplug. |
b86ff981 | 436 | */ |
23c88752 | 437 | static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu) |
b86ff981 | 438 | { |
23c88752 | 439 | struct rchan_buf *buf = NULL; |
b86ff981 JA |
440 | struct dentry *dentry; |
441 | ||
23c88752 | 442 | if (chan->is_global) |
b86ff981 JA |
443 | return chan->buf[0]; |
444 | ||
445 | buf = relay_create_buf(chan); | |
446 | if (!buf) | |
20d8b67c EGM |
447 | return NULL; |
448 | ||
449 | if (chan->has_base_filename) { | |
450 | dentry = relay_create_buf_file(chan, buf, cpu); | |
451 | if (!dentry) | |
452 | goto free_buf; | |
453 | relay_set_buf_dentry(buf, dentry); | |
59dbb2a0 AG |
454 | } else { |
455 | /* Only retrieve global info, nothing more, nothing less */ | |
456 | dentry = chan->cb->create_buf_file(NULL, NULL, | |
457 | S_IRUSR, buf, | |
458 | &chan->is_global); | |
459 | if (WARN_ON(dentry)) | |
460 | goto free_buf; | |
20d8b67c | 461 | } |
23c88752 MD |
462 | |
463 | buf->cpu = cpu; | |
464 | __relay_reset(buf, 1); | |
b86ff981 | 465 | |
23c88752 MD |
466 | if(chan->is_global) { |
467 | chan->buf[0] = buf; | |
468 | buf->cpu = 0; | |
469 | } | |
470 | ||
20d8b67c | 471 | return buf; |
23c88752 MD |
472 | |
473 | free_buf: | |
474 | relay_destroy_buf(buf); | |
20d8b67c | 475 | return NULL; |
b86ff981 JA |
476 | } |
477 | ||
478 | /** | |
479 | * relay_close_buf - close a channel buffer | |
480 | * @buf: channel buffer | |
481 | * | |
482 | * Marks the buffer finalized and restores the default callbacks. | |
483 | * The channel buffer and channel buffer data structure are then freed | |
484 | * automatically when the last reference is given up. | |
485 | */ | |
192636ad | 486 | static void relay_close_buf(struct rchan_buf *buf) |
b86ff981 JA |
487 | { |
488 | buf->finalized = 1; | |
7c9cb383 | 489 | del_timer_sync(&buf->timer); |
b8d4a5bf | 490 | buf->chan->cb->remove_buf_file(buf->dentry); |
b86ff981 JA |
491 | kref_put(&buf->kref, relay_remove_buf); |
492 | } | |
493 | ||
192636ad | 494 | static void setup_callbacks(struct rchan *chan, |
b86ff981 JA |
495 | struct rchan_callbacks *cb) |
496 | { | |
497 | if (!cb) { | |
498 | chan->cb = &default_channel_callbacks; | |
499 | return; | |
500 | } | |
501 | ||
502 | if (!cb->subbuf_start) | |
503 | cb->subbuf_start = subbuf_start_default_callback; | |
504 | if (!cb->buf_mapped) | |
505 | cb->buf_mapped = buf_mapped_default_callback; | |
506 | if (!cb->buf_unmapped) | |
507 | cb->buf_unmapped = buf_unmapped_default_callback; | |
508 | if (!cb->create_buf_file) | |
509 | cb->create_buf_file = create_buf_file_default_callback; | |
510 | if (!cb->remove_buf_file) | |
511 | cb->remove_buf_file = remove_buf_file_default_callback; | |
512 | chan->cb = cb; | |
513 | } | |
514 | ||
23c88752 | 515 | /** |
23c88752 MD |
516 | * relay_hotcpu_callback - CPU hotplug callback |
517 | * @nb: notifier block | |
518 | * @action: hotplug action to take | |
519 | * @hcpu: CPU number | |
520 | * | |
05fb6bf0 | 521 | * Returns the success/failure of the operation. (%NOTIFY_OK, %NOTIFY_BAD) |
23c88752 | 522 | */ |
0db0628d | 523 | static int relay_hotcpu_callback(struct notifier_block *nb, |
23c88752 MD |
524 | unsigned long action, |
525 | void *hcpu) | |
526 | { | |
527 | unsigned int hotcpu = (unsigned long)hcpu; | |
528 | struct rchan *chan; | |
529 | ||
530 | switch(action) { | |
531 | case CPU_UP_PREPARE: | |
8bb78442 | 532 | case CPU_UP_PREPARE_FROZEN: |
23c88752 MD |
533 | mutex_lock(&relay_channels_mutex); |
534 | list_for_each_entry(chan, &relay_channels, list) { | |
535 | if (chan->buf[hotcpu]) | |
536 | continue; | |
537 | chan->buf[hotcpu] = relay_open_buf(chan, hotcpu); | |
538 | if(!chan->buf[hotcpu]) { | |
539 | printk(KERN_ERR | |
540 | "relay_hotcpu_callback: cpu %d buffer " | |
541 | "creation failed\n", hotcpu); | |
542 | mutex_unlock(&relay_channels_mutex); | |
80b5184c | 543 | return notifier_from_errno(-ENOMEM); |
23c88752 MD |
544 | } |
545 | } | |
546 | mutex_unlock(&relay_channels_mutex); | |
547 | break; | |
548 | case CPU_DEAD: | |
8bb78442 | 549 | case CPU_DEAD_FROZEN: |
23c88752 MD |
550 | /* No need to flush the cpu : will be flushed upon |
551 | * final relay_flush() call. */ | |
552 | break; | |
553 | } | |
554 | return NOTIFY_OK; | |
555 | } | |
556 | ||
b86ff981 JA |
557 | /** |
558 | * relay_open - create a new relay channel | |
20d8b67c EGM |
559 | * @base_filename: base name of files to create, %NULL for buffering only |
560 | * @parent: dentry of parent directory, %NULL for root directory or buffer | |
b86ff981 JA |
561 | * @subbuf_size: size of sub-buffers |
562 | * @n_subbufs: number of sub-buffers | |
563 | * @cb: client callback functions | |
23c88752 | 564 | * @private_data: user-defined data |
b86ff981 | 565 | * |
4c78a663 | 566 | * Returns channel pointer if successful, %NULL otherwise. |
b86ff981 JA |
567 | * |
568 | * Creates a channel buffer for each cpu using the sizes and | |
569 | * attributes specified. The created channel buffer files | |
570 | * will be named base_filename0...base_filenameN-1. File | |
72fd4a35 | 571 | * permissions will be %S_IRUSR. |
59dbb2a0 AG |
572 | * |
573 | * If opening a buffer (@parent = NULL) that you later wish to register | |
574 | * in a filesystem, call relay_late_setup_files() once the @parent dentry | |
575 | * is available. | |
b86ff981 JA |
576 | */ |
577 | struct rchan *relay_open(const char *base_filename, | |
578 | struct dentry *parent, | |
579 | size_t subbuf_size, | |
580 | size_t n_subbufs, | |
23c88752 MD |
581 | struct rchan_callbacks *cb, |
582 | void *private_data) | |
b86ff981 JA |
583 | { |
584 | unsigned int i; | |
585 | struct rchan *chan; | |
b86ff981 JA |
586 | |
587 | if (!(subbuf_size && n_subbufs)) | |
588 | return NULL; | |
f6302f1b DC |
589 | if (subbuf_size > UINT_MAX / n_subbufs) |
590 | return NULL; | |
b86ff981 | 591 | |
cd861280 | 592 | chan = kzalloc(sizeof(struct rchan), GFP_KERNEL); |
b86ff981 JA |
593 | if (!chan) |
594 | return NULL; | |
595 | ||
596 | chan->version = RELAYFS_CHANNEL_VERSION; | |
597 | chan->n_subbufs = n_subbufs; | |
598 | chan->subbuf_size = subbuf_size; | |
a05342cb | 599 | chan->alloc_size = PAGE_ALIGN(subbuf_size * n_subbufs); |
23c88752 MD |
600 | chan->parent = parent; |
601 | chan->private_data = private_data; | |
20d8b67c EGM |
602 | if (base_filename) { |
603 | chan->has_base_filename = 1; | |
604 | strlcpy(chan->base_filename, base_filename, NAME_MAX); | |
605 | } | |
b86ff981 JA |
606 | setup_callbacks(chan, cb); |
607 | kref_init(&chan->kref); | |
608 | ||
23c88752 | 609 | mutex_lock(&relay_channels_mutex); |
b86ff981 | 610 | for_each_online_cpu(i) { |
23c88752 | 611 | chan->buf[i] = relay_open_buf(chan, i); |
b86ff981 JA |
612 | if (!chan->buf[i]) |
613 | goto free_bufs; | |
b86ff981 | 614 | } |
23c88752 MD |
615 | list_add(&chan->list, &relay_channels); |
616 | mutex_unlock(&relay_channels_mutex); | |
b86ff981 | 617 | |
b86ff981 JA |
618 | return chan; |
619 | ||
620 | free_bufs: | |
98ba4031 LJ |
621 | for_each_possible_cpu(i) { |
622 | if (chan->buf[i]) | |
623 | relay_close_buf(chan->buf[i]); | |
b86ff981 | 624 | } |
b86ff981 | 625 | |
b86ff981 | 626 | kref_put(&chan->kref, relay_destroy_channel); |
23c88752 | 627 | mutex_unlock(&relay_channels_mutex); |
ba62bafe | 628 | kfree(chan); |
b86ff981 JA |
629 | return NULL; |
630 | } | |
631 | EXPORT_SYMBOL_GPL(relay_open); | |
632 | ||
20d8b67c EGM |
633 | struct rchan_percpu_buf_dispatcher { |
634 | struct rchan_buf *buf; | |
635 | struct dentry *dentry; | |
636 | }; | |
637 | ||
638 | /* Called in atomic context. */ | |
639 | static void __relay_set_buf_dentry(void *info) | |
640 | { | |
641 | struct rchan_percpu_buf_dispatcher *p = info; | |
642 | ||
643 | relay_set_buf_dentry(p->buf, p->dentry); | |
644 | } | |
645 | ||
646 | /** | |
647 | * relay_late_setup_files - triggers file creation | |
648 | * @chan: channel to operate on | |
649 | * @base_filename: base name of files to create | |
650 | * @parent: dentry of parent directory, %NULL for root directory | |
651 | * | |
652 | * Returns 0 if successful, non-zero otherwise. | |
653 | * | |
59dbb2a0 AG |
654 | * Use to setup files for a previously buffer-only channel created |
655 | * by relay_open() with a NULL parent dentry. | |
656 | * | |
657 | * For example, this is useful for perfomring early tracing in kernel, | |
658 | * before VFS is up and then exposing the early results once the dentry | |
659 | * is available. | |
20d8b67c EGM |
660 | */ |
661 | int relay_late_setup_files(struct rchan *chan, | |
662 | const char *base_filename, | |
663 | struct dentry *parent) | |
664 | { | |
665 | int err = 0; | |
666 | unsigned int i, curr_cpu; | |
667 | unsigned long flags; | |
668 | struct dentry *dentry; | |
669 | struct rchan_percpu_buf_dispatcher disp; | |
670 | ||
671 | if (!chan || !base_filename) | |
672 | return -EINVAL; | |
673 | ||
674 | strlcpy(chan->base_filename, base_filename, NAME_MAX); | |
675 | ||
676 | mutex_lock(&relay_channels_mutex); | |
677 | /* Is chan already set up? */ | |
b786c6a9 JS |
678 | if (unlikely(chan->has_base_filename)) { |
679 | mutex_unlock(&relay_channels_mutex); | |
20d8b67c | 680 | return -EEXIST; |
b786c6a9 | 681 | } |
20d8b67c EGM |
682 | chan->has_base_filename = 1; |
683 | chan->parent = parent; | |
59dbb2a0 AG |
684 | |
685 | if (chan->is_global) { | |
686 | err = -EINVAL; | |
687 | if (!WARN_ON_ONCE(!chan->buf[0])) { | |
688 | dentry = relay_create_buf_file(chan, chan->buf[0], 0); | |
689 | if (dentry && !WARN_ON_ONCE(!chan->is_global)) { | |
690 | relay_set_buf_dentry(chan->buf[0], dentry); | |
691 | err = 0; | |
692 | } | |
693 | } | |
694 | mutex_unlock(&relay_channels_mutex); | |
695 | return err; | |
696 | } | |
697 | ||
20d8b67c EGM |
698 | curr_cpu = get_cpu(); |
699 | /* | |
700 | * The CPU hotplug notifier ran before us and created buffers with | |
701 | * no files associated. So it's safe to call relay_setup_buf_file() | |
702 | * on all currently online CPUs. | |
703 | */ | |
704 | for_each_online_cpu(i) { | |
705 | if (unlikely(!chan->buf[i])) { | |
7a51cffb | 706 | WARN_ONCE(1, KERN_ERR "CPU has no buffer!\n"); |
20d8b67c EGM |
707 | err = -EINVAL; |
708 | break; | |
709 | } | |
710 | ||
711 | dentry = relay_create_buf_file(chan, chan->buf[i], i); | |
712 | if (unlikely(!dentry)) { | |
713 | err = -EINVAL; | |
714 | break; | |
715 | } | |
716 | ||
717 | if (curr_cpu == i) { | |
718 | local_irq_save(flags); | |
719 | relay_set_buf_dentry(chan->buf[i], dentry); | |
720 | local_irq_restore(flags); | |
721 | } else { | |
722 | disp.buf = chan->buf[i]; | |
723 | disp.dentry = dentry; | |
724 | smp_mb(); | |
725 | /* relay_channels_mutex must be held, so wait. */ | |
726 | err = smp_call_function_single(i, | |
727 | __relay_set_buf_dentry, | |
728 | &disp, 1); | |
729 | } | |
730 | if (unlikely(err)) | |
731 | break; | |
732 | } | |
733 | put_cpu(); | |
734 | mutex_unlock(&relay_channels_mutex); | |
735 | ||
736 | return err; | |
737 | } | |
59dbb2a0 | 738 | EXPORT_SYMBOL_GPL(relay_late_setup_files); |
20d8b67c | 739 | |
b86ff981 JA |
740 | /** |
741 | * relay_switch_subbuf - switch to a new sub-buffer | |
742 | * @buf: channel buffer | |
743 | * @length: size of current event | |
744 | * | |
745 | * Returns either the length passed in or 0 if full. | |
746 | * | |
747 | * Performs sub-buffer-switch tasks such as invoking callbacks, | |
748 | * updating padding counts, waking up readers, etc. | |
749 | */ | |
750 | size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length) | |
751 | { | |
752 | void *old, *new; | |
753 | size_t old_subbuf, new_subbuf; | |
754 | ||
755 | if (unlikely(length > buf->chan->subbuf_size)) | |
756 | goto toobig; | |
757 | ||
758 | if (buf->offset != buf->chan->subbuf_size + 1) { | |
759 | buf->prev_padding = buf->chan->subbuf_size - buf->offset; | |
760 | old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; | |
761 | buf->padding[old_subbuf] = buf->prev_padding; | |
762 | buf->subbufs_produced++; | |
20d8b67c | 763 | if (buf->dentry) |
7682c918 | 764 | d_inode(buf->dentry)->i_size += |
20d8b67c EGM |
765 | buf->chan->subbuf_size - |
766 | buf->padding[old_subbuf]; | |
767 | else | |
768 | buf->early_bytes += buf->chan->subbuf_size - | |
769 | buf->padding[old_subbuf]; | |
221415d7 | 770 | smp_mb(); |
7c9cb383 TZ |
771 | if (waitqueue_active(&buf->read_wait)) |
772 | /* | |
773 | * Calling wake_up_interruptible() from here | |
774 | * will deadlock if we happen to be logging | |
775 | * from the scheduler (trying to re-grab | |
776 | * rq->lock), so defer it. | |
777 | */ | |
74019224 | 778 | mod_timer(&buf->timer, jiffies + 1); |
b86ff981 JA |
779 | } |
780 | ||
781 | old = buf->data; | |
782 | new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; | |
783 | new = buf->start + new_subbuf * buf->chan->subbuf_size; | |
784 | buf->offset = 0; | |
785 | if (!buf->chan->cb->subbuf_start(buf, new, old, buf->prev_padding)) { | |
786 | buf->offset = buf->chan->subbuf_size + 1; | |
787 | return 0; | |
788 | } | |
789 | buf->data = new; | |
790 | buf->padding[new_subbuf] = 0; | |
791 | ||
792 | if (unlikely(length + buf->offset > buf->chan->subbuf_size)) | |
793 | goto toobig; | |
794 | ||
795 | return length; | |
796 | ||
797 | toobig: | |
798 | buf->chan->last_toobig = length; | |
799 | return 0; | |
800 | } | |
801 | EXPORT_SYMBOL_GPL(relay_switch_subbuf); | |
802 | ||
803 | /** | |
804 | * relay_subbufs_consumed - update the buffer's sub-buffers-consumed count | |
805 | * @chan: the channel | |
806 | * @cpu: the cpu associated with the channel buffer to update | |
807 | * @subbufs_consumed: number of sub-buffers to add to current buf's count | |
808 | * | |
809 | * Adds to the channel buffer's consumed sub-buffer count. | |
810 | * subbufs_consumed should be the number of sub-buffers newly consumed, | |
811 | * not the total consumed. | |
812 | * | |
72fd4a35 | 813 | * NOTE. Kernel clients don't need to call this function if the channel |
b86ff981 JA |
814 | * mode is 'overwrite'. |
815 | */ | |
816 | void relay_subbufs_consumed(struct rchan *chan, | |
817 | unsigned int cpu, | |
818 | size_t subbufs_consumed) | |
819 | { | |
820 | struct rchan_buf *buf; | |
821 | ||
822 | if (!chan) | |
823 | return; | |
824 | ||
2c53d910 AS |
825 | if (cpu >= NR_CPUS || !chan->buf[cpu] || |
826 | subbufs_consumed > chan->n_subbufs) | |
b86ff981 JA |
827 | return; |
828 | ||
829 | buf = chan->buf[cpu]; | |
2c53d910 | 830 | if (subbufs_consumed > buf->subbufs_produced - buf->subbufs_consumed) |
b86ff981 | 831 | buf->subbufs_consumed = buf->subbufs_produced; |
2c53d910 AS |
832 | else |
833 | buf->subbufs_consumed += subbufs_consumed; | |
b86ff981 JA |
834 | } |
835 | EXPORT_SYMBOL_GPL(relay_subbufs_consumed); | |
836 | ||
837 | /** | |
838 | * relay_close - close the channel | |
839 | * @chan: the channel | |
840 | * | |
841 | * Closes all channel buffers and frees the channel. | |
842 | */ | |
843 | void relay_close(struct rchan *chan) | |
844 | { | |
845 | unsigned int i; | |
b86ff981 JA |
846 | |
847 | if (!chan) | |
848 | return; | |
849 | ||
23c88752 MD |
850 | mutex_lock(&relay_channels_mutex); |
851 | if (chan->is_global && chan->buf[0]) | |
852 | relay_close_buf(chan->buf[0]); | |
853 | else | |
854 | for_each_possible_cpu(i) | |
855 | if (chan->buf[i]) | |
856 | relay_close_buf(chan->buf[i]); | |
b86ff981 JA |
857 | |
858 | if (chan->last_toobig) | |
859 | printk(KERN_WARNING "relay: one or more items not logged " | |
860 | "[item size (%Zd) > sub-buffer size (%Zd)]\n", | |
861 | chan->last_toobig, chan->subbuf_size); | |
862 | ||
23c88752 | 863 | list_del(&chan->list); |
b86ff981 | 864 | kref_put(&chan->kref, relay_destroy_channel); |
23c88752 | 865 | mutex_unlock(&relay_channels_mutex); |
b86ff981 JA |
866 | } |
867 | EXPORT_SYMBOL_GPL(relay_close); | |
868 | ||
869 | /** | |
870 | * relay_flush - close the channel | |
871 | * @chan: the channel | |
872 | * | |
4c78a663 | 873 | * Flushes all channel buffers, i.e. forces buffer switch. |
b86ff981 JA |
874 | */ |
875 | void relay_flush(struct rchan *chan) | |
876 | { | |
877 | unsigned int i; | |
b86ff981 JA |
878 | |
879 | if (!chan) | |
880 | return; | |
881 | ||
23c88752 MD |
882 | if (chan->is_global && chan->buf[0]) { |
883 | relay_switch_subbuf(chan->buf[0], 0); | |
884 | return; | |
b86ff981 | 885 | } |
23c88752 MD |
886 | |
887 | mutex_lock(&relay_channels_mutex); | |
888 | for_each_possible_cpu(i) | |
889 | if (chan->buf[i]) | |
890 | relay_switch_subbuf(chan->buf[i], 0); | |
891 | mutex_unlock(&relay_channels_mutex); | |
b86ff981 JA |
892 | } |
893 | EXPORT_SYMBOL_GPL(relay_flush); | |
894 | ||
895 | /** | |
896 | * relay_file_open - open file op for relay files | |
897 | * @inode: the inode | |
898 | * @filp: the file | |
899 | * | |
900 | * Increments the channel buffer refcount. | |
901 | */ | |
902 | static int relay_file_open(struct inode *inode, struct file *filp) | |
903 | { | |
8e18e294 | 904 | struct rchan_buf *buf = inode->i_private; |
b86ff981 JA |
905 | kref_get(&buf->kref); |
906 | filp->private_data = buf; | |
907 | ||
37529fe9 | 908 | return nonseekable_open(inode, filp); |
b86ff981 JA |
909 | } |
910 | ||
911 | /** | |
912 | * relay_file_mmap - mmap file op for relay files | |
913 | * @filp: the file | |
914 | * @vma: the vma describing what to map | |
915 | * | |
72fd4a35 | 916 | * Calls upon relay_mmap_buf() to map the file into user space. |
b86ff981 JA |
917 | */ |
918 | static int relay_file_mmap(struct file *filp, struct vm_area_struct *vma) | |
919 | { | |
920 | struct rchan_buf *buf = filp->private_data; | |
921 | return relay_mmap_buf(buf, vma); | |
922 | } | |
923 | ||
924 | /** | |
925 | * relay_file_poll - poll file op for relay files | |
926 | * @filp: the file | |
927 | * @wait: poll table | |
928 | * | |
929 | * Poll implemention. | |
930 | */ | |
931 | static unsigned int relay_file_poll(struct file *filp, poll_table *wait) | |
932 | { | |
933 | unsigned int mask = 0; | |
934 | struct rchan_buf *buf = filp->private_data; | |
935 | ||
936 | if (buf->finalized) | |
937 | return POLLERR; | |
938 | ||
939 | if (filp->f_mode & FMODE_READ) { | |
940 | poll_wait(filp, &buf->read_wait, wait); | |
941 | if (!relay_buf_empty(buf)) | |
942 | mask |= POLLIN | POLLRDNORM; | |
943 | } | |
944 | ||
945 | return mask; | |
946 | } | |
947 | ||
948 | /** | |
949 | * relay_file_release - release file op for relay files | |
950 | * @inode: the inode | |
951 | * @filp: the file | |
952 | * | |
953 | * Decrements the channel refcount, as the filesystem is | |
954 | * no longer using it. | |
955 | */ | |
956 | static int relay_file_release(struct inode *inode, struct file *filp) | |
957 | { | |
958 | struct rchan_buf *buf = filp->private_data; | |
959 | kref_put(&buf->kref, relay_remove_buf); | |
960 | ||
961 | return 0; | |
962 | } | |
963 | ||
4c78a663 | 964 | /* |
b86ff981 JA |
965 | * relay_file_read_consume - update the consumed count for the buffer |
966 | */ | |
967 | static void relay_file_read_consume(struct rchan_buf *buf, | |
968 | size_t read_pos, | |
969 | size_t bytes_consumed) | |
970 | { | |
971 | size_t subbuf_size = buf->chan->subbuf_size; | |
972 | size_t n_subbufs = buf->chan->n_subbufs; | |
973 | size_t read_subbuf; | |
974 | ||
32194450 TZ |
975 | if (buf->subbufs_produced == buf->subbufs_consumed && |
976 | buf->offset == buf->bytes_consumed) | |
977 | return; | |
978 | ||
b86ff981 JA |
979 | if (buf->bytes_consumed + bytes_consumed > subbuf_size) { |
980 | relay_subbufs_consumed(buf->chan, buf->cpu, 1); | |
981 | buf->bytes_consumed = 0; | |
982 | } | |
983 | ||
984 | buf->bytes_consumed += bytes_consumed; | |
a66e356c MH |
985 | if (!read_pos) |
986 | read_subbuf = buf->subbufs_consumed % n_subbufs; | |
987 | else | |
988 | read_subbuf = read_pos / buf->chan->subbuf_size; | |
b86ff981 JA |
989 | if (buf->bytes_consumed + buf->padding[read_subbuf] == subbuf_size) { |
990 | if ((read_subbuf == buf->subbufs_produced % n_subbufs) && | |
991 | (buf->offset == subbuf_size)) | |
992 | return; | |
993 | relay_subbufs_consumed(buf->chan, buf->cpu, 1); | |
994 | buf->bytes_consumed = 0; | |
995 | } | |
996 | } | |
997 | ||
4c78a663 | 998 | /* |
b86ff981 JA |
999 | * relay_file_read_avail - boolean, are there unconsumed bytes available? |
1000 | */ | |
1001 | static int relay_file_read_avail(struct rchan_buf *buf, size_t read_pos) | |
1002 | { | |
b86ff981 JA |
1003 | size_t subbuf_size = buf->chan->subbuf_size; |
1004 | size_t n_subbufs = buf->chan->n_subbufs; | |
221415d7 JA |
1005 | size_t produced = buf->subbufs_produced; |
1006 | size_t consumed = buf->subbufs_consumed; | |
b86ff981 | 1007 | |
221415d7 | 1008 | relay_file_read_consume(buf, read_pos, 0); |
b86ff981 | 1009 | |
32194450 TZ |
1010 | consumed = buf->subbufs_consumed; |
1011 | ||
221415d7 JA |
1012 | if (unlikely(buf->offset > subbuf_size)) { |
1013 | if (produced == consumed) | |
1014 | return 0; | |
1015 | return 1; | |
b86ff981 JA |
1016 | } |
1017 | ||
221415d7 | 1018 | if (unlikely(produced - consumed >= n_subbufs)) { |
a66e356c | 1019 | consumed = produced - n_subbufs + 1; |
221415d7 | 1020 | buf->subbufs_consumed = consumed; |
a66e356c | 1021 | buf->bytes_consumed = 0; |
221415d7 | 1022 | } |
1bfbc608 | 1023 | |
221415d7 JA |
1024 | produced = (produced % n_subbufs) * subbuf_size + buf->offset; |
1025 | consumed = (consumed % n_subbufs) * subbuf_size + buf->bytes_consumed; | |
1026 | ||
1027 | if (consumed > produced) | |
1028 | produced += n_subbufs * subbuf_size; | |
1bfbc608 | 1029 | |
32194450 TZ |
1030 | if (consumed == produced) { |
1031 | if (buf->offset == subbuf_size && | |
1032 | buf->subbufs_produced > buf->subbufs_consumed) | |
1033 | return 1; | |
b86ff981 | 1034 | return 0; |
32194450 | 1035 | } |
b86ff981 | 1036 | |
b86ff981 JA |
1037 | return 1; |
1038 | } | |
1039 | ||
1040 | /** | |
1041 | * relay_file_read_subbuf_avail - return bytes available in sub-buffer | |
4c78a663 RD |
1042 | * @read_pos: file read position |
1043 | * @buf: relay channel buffer | |
b86ff981 JA |
1044 | */ |
1045 | static size_t relay_file_read_subbuf_avail(size_t read_pos, | |
1046 | struct rchan_buf *buf) | |
1047 | { | |
1048 | size_t padding, avail = 0; | |
1049 | size_t read_subbuf, read_offset, write_subbuf, write_offset; | |
1050 | size_t subbuf_size = buf->chan->subbuf_size; | |
1051 | ||
1052 | write_subbuf = (buf->data - buf->start) / subbuf_size; | |
1053 | write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset; | |
1054 | read_subbuf = read_pos / subbuf_size; | |
1055 | read_offset = read_pos % subbuf_size; | |
1056 | padding = buf->padding[read_subbuf]; | |
1057 | ||
1058 | if (read_subbuf == write_subbuf) { | |
1059 | if (read_offset + padding < write_offset) | |
1060 | avail = write_offset - (read_offset + padding); | |
1061 | } else | |
1062 | avail = (subbuf_size - padding) - read_offset; | |
1063 | ||
1064 | return avail; | |
1065 | } | |
1066 | ||
1067 | /** | |
1068 | * relay_file_read_start_pos - find the first available byte to read | |
4c78a663 RD |
1069 | * @read_pos: file read position |
1070 | * @buf: relay channel buffer | |
b86ff981 | 1071 | * |
72fd4a35 | 1072 | * If the @read_pos is in the middle of padding, return the |
b86ff981 JA |
1073 | * position of the first actually available byte, otherwise |
1074 | * return the original value. | |
1075 | */ | |
1076 | static size_t relay_file_read_start_pos(size_t read_pos, | |
1077 | struct rchan_buf *buf) | |
1078 | { | |
1079 | size_t read_subbuf, padding, padding_start, padding_end; | |
1080 | size_t subbuf_size = buf->chan->subbuf_size; | |
1081 | size_t n_subbufs = buf->chan->n_subbufs; | |
8d62fdeb | 1082 | size_t consumed = buf->subbufs_consumed % n_subbufs; |
b86ff981 | 1083 | |
8d62fdeb DW |
1084 | if (!read_pos) |
1085 | read_pos = consumed * subbuf_size + buf->bytes_consumed; | |
b86ff981 JA |
1086 | read_subbuf = read_pos / subbuf_size; |
1087 | padding = buf->padding[read_subbuf]; | |
1088 | padding_start = (read_subbuf + 1) * subbuf_size - padding; | |
1089 | padding_end = (read_subbuf + 1) * subbuf_size; | |
1090 | if (read_pos >= padding_start && read_pos < padding_end) { | |
1091 | read_subbuf = (read_subbuf + 1) % n_subbufs; | |
1092 | read_pos = read_subbuf * subbuf_size; | |
1093 | } | |
1094 | ||
1095 | return read_pos; | |
1096 | } | |
1097 | ||
1098 | /** | |
1099 | * relay_file_read_end_pos - return the new read position | |
4c78a663 RD |
1100 | * @read_pos: file read position |
1101 | * @buf: relay channel buffer | |
1102 | * @count: number of bytes to be read | |
b86ff981 JA |
1103 | */ |
1104 | static size_t relay_file_read_end_pos(struct rchan_buf *buf, | |
1105 | size_t read_pos, | |
1106 | size_t count) | |
1107 | { | |
1108 | size_t read_subbuf, padding, end_pos; | |
1109 | size_t subbuf_size = buf->chan->subbuf_size; | |
1110 | size_t n_subbufs = buf->chan->n_subbufs; | |
1111 | ||
1112 | read_subbuf = read_pos / subbuf_size; | |
1113 | padding = buf->padding[read_subbuf]; | |
1114 | if (read_pos % subbuf_size + count + padding == subbuf_size) | |
1115 | end_pos = (read_subbuf + 1) * subbuf_size; | |
1116 | else | |
1117 | end_pos = read_pos + count; | |
1118 | if (end_pos >= subbuf_size * n_subbufs) | |
1119 | end_pos = 0; | |
1120 | ||
1121 | return end_pos; | |
1122 | } | |
1123 | ||
4c78a663 | 1124 | /* |
6dac40a7 | 1125 | * subbuf_read_actor - read up to one subbuf's worth of data |
b86ff981 | 1126 | */ |
6dac40a7 TZ |
1127 | static int subbuf_read_actor(size_t read_start, |
1128 | struct rchan_buf *buf, | |
1129 | size_t avail, | |
8359f689 | 1130 | read_descriptor_t *desc) |
b86ff981 | 1131 | { |
b86ff981 | 1132 | void *from; |
6dac40a7 | 1133 | int ret = 0; |
b86ff981 JA |
1134 | |
1135 | from = buf->start + read_start; | |
6dac40a7 | 1136 | ret = avail; |
ba2397ef | 1137 | if (copy_to_user(desc->arg.buf, from, avail)) { |
6dac40a7 TZ |
1138 | desc->error = -EFAULT; |
1139 | ret = 0; | |
b86ff981 | 1140 | } |
6dac40a7 TZ |
1141 | desc->arg.data += ret; |
1142 | desc->written += ret; | |
1143 | desc->count -= ret; | |
1144 | ||
b86ff981 JA |
1145 | return ret; |
1146 | } | |
1147 | ||
6dac40a7 TZ |
1148 | typedef int (*subbuf_actor_t) (size_t read_start, |
1149 | struct rchan_buf *buf, | |
1150 | size_t avail, | |
8359f689 | 1151 | read_descriptor_t *desc); |
6dac40a7 | 1152 | |
4c78a663 | 1153 | /* |
6dac40a7 TZ |
1154 | * relay_file_read_subbufs - read count bytes, bridging subbuf boundaries |
1155 | */ | |
192636ad AM |
1156 | static ssize_t relay_file_read_subbufs(struct file *filp, loff_t *ppos, |
1157 | subbuf_actor_t subbuf_actor, | |
192636ad | 1158 | read_descriptor_t *desc) |
221415d7 | 1159 | { |
6dac40a7 TZ |
1160 | struct rchan_buf *buf = filp->private_data; |
1161 | size_t read_start, avail; | |
6dac40a7 | 1162 | int ret; |
221415d7 | 1163 | |
ba2397ef | 1164 | if (!desc->count) |
221415d7 JA |
1165 | return 0; |
1166 | ||
5955102c | 1167 | inode_lock(file_inode(filp)); |
221415d7 | 1168 | do { |
6dac40a7 TZ |
1169 | if (!relay_file_read_avail(buf, *ppos)) |
1170 | break; | |
1171 | ||
1172 | read_start = relay_file_read_start_pos(*ppos, buf); | |
1173 | avail = relay_file_read_subbuf_avail(read_start, buf); | |
1174 | if (!avail) | |
221415d7 | 1175 | break; |
221415d7 | 1176 | |
ba2397ef | 1177 | avail = min(desc->count, avail); |
8359f689 | 1178 | ret = subbuf_actor(read_start, buf, avail, desc); |
ba2397ef | 1179 | if (desc->error < 0) |
6dac40a7 TZ |
1180 | break; |
1181 | ||
1182 | if (ret) { | |
1183 | relay_file_read_consume(buf, read_start, ret); | |
1184 | *ppos = relay_file_read_end_pos(buf, read_start, ret); | |
1185 | } | |
ba2397ef | 1186 | } while (desc->count && ret); |
5955102c | 1187 | inode_unlock(file_inode(filp)); |
6dac40a7 | 1188 | |
ba2397ef | 1189 | return desc->written; |
6dac40a7 TZ |
1190 | } |
1191 | ||
1192 | static ssize_t relay_file_read(struct file *filp, | |
1193 | char __user *buffer, | |
1194 | size_t count, | |
1195 | loff_t *ppos) | |
1196 | { | |
ba2397ef AV |
1197 | read_descriptor_t desc; |
1198 | desc.written = 0; | |
1199 | desc.count = count; | |
1200 | desc.arg.buf = buffer; | |
1201 | desc.error = 0; | |
8359f689 | 1202 | return relay_file_read_subbufs(filp, ppos, subbuf_read_actor, &desc); |
6dac40a7 TZ |
1203 | } |
1204 | ||
1db60cf2 JA |
1205 | static void relay_consume_bytes(struct rchan_buf *rbuf, int bytes_consumed) |
1206 | { | |
1207 | rbuf->bytes_consumed += bytes_consumed; | |
1208 | ||
1209 | if (rbuf->bytes_consumed >= rbuf->chan->subbuf_size) { | |
1210 | relay_subbufs_consumed(rbuf->chan, rbuf->cpu, 1); | |
1211 | rbuf->bytes_consumed %= rbuf->chan->subbuf_size; | |
1212 | } | |
1213 | } | |
1214 | ||
ebf99093 TZ |
1215 | static void relay_pipe_buf_release(struct pipe_inode_info *pipe, |
1216 | struct pipe_buffer *buf) | |
6dac40a7 | 1217 | { |
ebf99093 TZ |
1218 | struct rchan_buf *rbuf; |
1219 | ||
1220 | rbuf = (struct rchan_buf *)page_private(buf->page); | |
1db60cf2 | 1221 | relay_consume_bytes(rbuf, buf->private); |
ebf99093 TZ |
1222 | } |
1223 | ||
28dfef8f | 1224 | static const struct pipe_buf_operations relay_pipe_buf_ops = { |
ebf99093 | 1225 | .can_merge = 0, |
cac36bb0 | 1226 | .confirm = generic_pipe_buf_confirm, |
ebf99093 TZ |
1227 | .release = relay_pipe_buf_release, |
1228 | .steal = generic_pipe_buf_steal, | |
1229 | .get = generic_pipe_buf_get, | |
1230 | }; | |
1231 | ||
5eb7f9fa JA |
1232 | static void relay_page_release(struct splice_pipe_desc *spd, unsigned int i) |
1233 | { | |
1234 | } | |
1235 | ||
d3f35d98 | 1236 | /* |
ebf99093 TZ |
1237 | * subbuf_splice_actor - splice up to one subbuf's worth of data |
1238 | */ | |
5f1664f9 | 1239 | static ssize_t subbuf_splice_actor(struct file *in, |
ebf99093 TZ |
1240 | loff_t *ppos, |
1241 | struct pipe_inode_info *pipe, | |
1242 | size_t len, | |
1243 | unsigned int flags, | |
1244 | int *nonpad_ret) | |
1245 | { | |
5f1664f9 | 1246 | unsigned int pidx, poff, total_len, subbuf_pages, nr_pages; |
ebf99093 TZ |
1247 | struct rchan_buf *rbuf = in->private_data; |
1248 | unsigned int subbuf_size = rbuf->chan->subbuf_size; | |
24da24de TZ |
1249 | uint64_t pos = (uint64_t) *ppos; |
1250 | uint32_t alloc_size = (uint32_t) rbuf->chan->alloc_size; | |
1251 | size_t read_start = (size_t) do_div(pos, alloc_size); | |
ebf99093 TZ |
1252 | size_t read_subbuf = read_start / subbuf_size; |
1253 | size_t padding = rbuf->padding[read_subbuf]; | |
1254 | size_t nonpad_end = read_subbuf * subbuf_size + subbuf_size - padding; | |
35f3d14d JA |
1255 | struct page *pages[PIPE_DEF_BUFFERS]; |
1256 | struct partial_page partial[PIPE_DEF_BUFFERS]; | |
1db60cf2 JA |
1257 | struct splice_pipe_desc spd = { |
1258 | .pages = pages, | |
1259 | .nr_pages = 0, | |
047fe360 | 1260 | .nr_pages_max = PIPE_DEF_BUFFERS, |
1db60cf2 JA |
1261 | .partial = partial, |
1262 | .flags = flags, | |
1263 | .ops = &relay_pipe_buf_ops, | |
5eb7f9fa | 1264 | .spd_release = relay_page_release, |
1db60cf2 | 1265 | }; |
5f1664f9 | 1266 | ssize_t ret; |
ebf99093 TZ |
1267 | |
1268 | if (rbuf->subbufs_produced == rbuf->subbufs_consumed) | |
1269 | return 0; | |
35f3d14d JA |
1270 | if (splice_grow_spd(pipe, &spd)) |
1271 | return -ENOMEM; | |
ebf99093 | 1272 | |
1db60cf2 JA |
1273 | /* |
1274 | * Adjust read len, if longer than what is available | |
1275 | */ | |
1276 | if (len > (subbuf_size - read_start % subbuf_size)) | |
1277 | len = subbuf_size - read_start % subbuf_size; | |
ebf99093 TZ |
1278 | |
1279 | subbuf_pages = rbuf->chan->alloc_size >> PAGE_SHIFT; | |
1280 | pidx = (read_start / PAGE_SIZE) % subbuf_pages; | |
1281 | poff = read_start & ~PAGE_MASK; | |
a786c06d | 1282 | nr_pages = min_t(unsigned int, subbuf_pages, spd.nr_pages_max); |
ebf99093 | 1283 | |
16d54669 | 1284 | for (total_len = 0; spd.nr_pages < nr_pages; spd.nr_pages++) { |
1db60cf2 JA |
1285 | unsigned int this_len, this_end, private; |
1286 | unsigned int cur_pos = read_start + total_len; | |
ebf99093 | 1287 | |
1db60cf2 | 1288 | if (!len) |
ebf99093 | 1289 | break; |
ebf99093 | 1290 | |
1db60cf2 JA |
1291 | this_len = min_t(unsigned long, len, PAGE_SIZE - poff); |
1292 | private = this_len; | |
ebf99093 | 1293 | |
1db60cf2 JA |
1294 | spd.pages[spd.nr_pages] = rbuf->page_array[pidx]; |
1295 | spd.partial[spd.nr_pages].offset = poff; | |
ebf99093 | 1296 | |
1db60cf2 JA |
1297 | this_end = cur_pos + this_len; |
1298 | if (this_end >= nonpad_end) { | |
1299 | this_len = nonpad_end - cur_pos; | |
1300 | private = this_len + padding; | |
ebf99093 | 1301 | } |
1db60cf2 JA |
1302 | spd.partial[spd.nr_pages].len = this_len; |
1303 | spd.partial[spd.nr_pages].private = private; | |
ebf99093 | 1304 | |
1db60cf2 JA |
1305 | len -= this_len; |
1306 | total_len += this_len; | |
1307 | poff = 0; | |
1308 | pidx = (pidx + 1) % subbuf_pages; | |
ebf99093 | 1309 | |
1db60cf2 JA |
1310 | if (this_end >= nonpad_end) { |
1311 | spd.nr_pages++; | |
ebf99093 TZ |
1312 | break; |
1313 | } | |
ebf99093 TZ |
1314 | } |
1315 | ||
35f3d14d | 1316 | ret = 0; |
1db60cf2 | 1317 | if (!spd.nr_pages) |
35f3d14d | 1318 | goto out; |
ebf99093 | 1319 | |
1db60cf2 JA |
1320 | ret = *nonpad_ret = splice_to_pipe(pipe, &spd); |
1321 | if (ret < 0 || ret < total_len) | |
35f3d14d | 1322 | goto out; |
ebf99093 | 1323 | |
1db60cf2 JA |
1324 | if (read_start + ret == nonpad_end) |
1325 | ret += padding; | |
1326 | ||
35f3d14d | 1327 | out: |
047fe360 ED |
1328 | splice_shrink_spd(&spd); |
1329 | return ret; | |
ebf99093 TZ |
1330 | } |
1331 | ||
1332 | static ssize_t relay_file_splice_read(struct file *in, | |
1333 | loff_t *ppos, | |
1334 | struct pipe_inode_info *pipe, | |
1335 | size_t len, | |
1336 | unsigned int flags) | |
1337 | { | |
1338 | ssize_t spliced; | |
1339 | int ret; | |
1340 | int nonpad_ret = 0; | |
1341 | ||
1342 | ret = 0; | |
1343 | spliced = 0; | |
1344 | ||
a82c53a0 | 1345 | while (len && !spliced) { |
ebf99093 TZ |
1346 | ret = subbuf_splice_actor(in, ppos, pipe, len, flags, &nonpad_ret); |
1347 | if (ret < 0) | |
1348 | break; | |
1349 | else if (!ret) { | |
fbb5b7ae | 1350 | if (flags & SPLICE_F_NONBLOCK) |
ebf99093 | 1351 | ret = -EAGAIN; |
fbb5b7ae | 1352 | break; |
ebf99093 TZ |
1353 | } |
1354 | ||
1355 | *ppos += ret; | |
1356 | if (ret > len) | |
1357 | len = 0; | |
1358 | else | |
1359 | len -= ret; | |
1360 | spliced += nonpad_ret; | |
1361 | nonpad_ret = 0; | |
1362 | } | |
1363 | ||
1364 | if (spliced) | |
1365 | return spliced; | |
1366 | ||
1367 | return ret; | |
221415d7 JA |
1368 | } |
1369 | ||
15ad7cdc | 1370 | const struct file_operations relay_file_operations = { |
b86ff981 JA |
1371 | .open = relay_file_open, |
1372 | .poll = relay_file_poll, | |
1373 | .mmap = relay_file_mmap, | |
1374 | .read = relay_file_read, | |
1375 | .llseek = no_llseek, | |
1376 | .release = relay_file_release, | |
ebf99093 | 1377 | .splice_read = relay_file_splice_read, |
b86ff981 JA |
1378 | }; |
1379 | EXPORT_SYMBOL_GPL(relay_file_operations); | |
23c88752 MD |
1380 | |
1381 | static __init int relay_init(void) | |
1382 | { | |
1383 | ||
1384 | hotcpu_notifier(relay_hotcpu_callback, 0); | |
1385 | return 0; | |
1386 | } | |
1387 | ||
20d8b67c | 1388 | early_initcall(relay_init); |