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Commit | Line | Data |
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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 | } |
017c59c0 | 217 | *per_cpu_ptr(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 | { | |
017c59c0 | 385 | struct rchan_buf *buf; |
b86ff981 | 386 | unsigned int i; |
b86ff981 JA |
387 | |
388 | if (!chan) | |
389 | return; | |
390 | ||
017c59c0 AG |
391 | if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0))) { |
392 | __relay_reset(buf, 0); | |
23c88752 | 393 | return; |
b86ff981 | 394 | } |
23c88752 MD |
395 | |
396 | mutex_lock(&relay_channels_mutex); | |
98ba4031 | 397 | for_each_possible_cpu(i) |
017c59c0 AG |
398 | if ((buf = *per_cpu_ptr(chan->buf, i))) |
399 | __relay_reset(buf, 0); | |
23c88752 | 400 | mutex_unlock(&relay_channels_mutex); |
b86ff981 JA |
401 | } |
402 | EXPORT_SYMBOL_GPL(relay_reset); | |
403 | ||
20d8b67c EGM |
404 | static inline void relay_set_buf_dentry(struct rchan_buf *buf, |
405 | struct dentry *dentry) | |
406 | { | |
407 | buf->dentry = dentry; | |
7682c918 | 408 | d_inode(buf->dentry)->i_size = buf->early_bytes; |
20d8b67c EGM |
409 | } |
410 | ||
411 | static struct dentry *relay_create_buf_file(struct rchan *chan, | |
412 | struct rchan_buf *buf, | |
413 | unsigned int cpu) | |
414 | { | |
415 | struct dentry *dentry; | |
416 | char *tmpname; | |
417 | ||
418 | tmpname = kzalloc(NAME_MAX + 1, GFP_KERNEL); | |
419 | if (!tmpname) | |
420 | return NULL; | |
421 | snprintf(tmpname, NAME_MAX, "%s%d", chan->base_filename, cpu); | |
422 | ||
423 | /* Create file in fs */ | |
424 | dentry = chan->cb->create_buf_file(tmpname, chan->parent, | |
425 | S_IRUSR, buf, | |
426 | &chan->is_global); | |
427 | ||
428 | kfree(tmpname); | |
429 | ||
430 | return dentry; | |
431 | } | |
432 | ||
4c78a663 | 433 | /* |
b86ff981 JA |
434 | * relay_open_buf - create a new relay channel buffer |
435 | * | |
23c88752 | 436 | * used by relay_open() and CPU hotplug. |
b86ff981 | 437 | */ |
23c88752 | 438 | static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu) |
b86ff981 | 439 | { |
23c88752 | 440 | struct rchan_buf *buf = NULL; |
b86ff981 JA |
441 | struct dentry *dentry; |
442 | ||
23c88752 | 443 | if (chan->is_global) |
017c59c0 | 444 | return *per_cpu_ptr(chan->buf, 0); |
b86ff981 JA |
445 | |
446 | buf = relay_create_buf(chan); | |
447 | if (!buf) | |
20d8b67c EGM |
448 | return NULL; |
449 | ||
450 | if (chan->has_base_filename) { | |
451 | dentry = relay_create_buf_file(chan, buf, cpu); | |
452 | if (!dentry) | |
453 | goto free_buf; | |
454 | relay_set_buf_dentry(buf, dentry); | |
59dbb2a0 AG |
455 | } else { |
456 | /* Only retrieve global info, nothing more, nothing less */ | |
457 | dentry = chan->cb->create_buf_file(NULL, NULL, | |
458 | S_IRUSR, buf, | |
459 | &chan->is_global); | |
460 | if (WARN_ON(dentry)) | |
461 | goto free_buf; | |
20d8b67c | 462 | } |
23c88752 MD |
463 | |
464 | buf->cpu = cpu; | |
465 | __relay_reset(buf, 1); | |
b86ff981 | 466 | |
23c88752 | 467 | if(chan->is_global) { |
017c59c0 | 468 | *per_cpu_ptr(chan->buf, 0) = buf; |
23c88752 MD |
469 | buf->cpu = 0; |
470 | } | |
471 | ||
20d8b67c | 472 | return buf; |
23c88752 MD |
473 | |
474 | free_buf: | |
475 | relay_destroy_buf(buf); | |
20d8b67c | 476 | return NULL; |
b86ff981 JA |
477 | } |
478 | ||
479 | /** | |
480 | * relay_close_buf - close a channel buffer | |
481 | * @buf: channel buffer | |
482 | * | |
483 | * Marks the buffer finalized and restores the default callbacks. | |
484 | * The channel buffer and channel buffer data structure are then freed | |
485 | * automatically when the last reference is given up. | |
486 | */ | |
192636ad | 487 | static void relay_close_buf(struct rchan_buf *buf) |
b86ff981 JA |
488 | { |
489 | buf->finalized = 1; | |
7c9cb383 | 490 | del_timer_sync(&buf->timer); |
b8d4a5bf | 491 | buf->chan->cb->remove_buf_file(buf->dentry); |
b86ff981 JA |
492 | kref_put(&buf->kref, relay_remove_buf); |
493 | } | |
494 | ||
192636ad | 495 | static void setup_callbacks(struct rchan *chan, |
b86ff981 JA |
496 | struct rchan_callbacks *cb) |
497 | { | |
498 | if (!cb) { | |
499 | chan->cb = &default_channel_callbacks; | |
500 | return; | |
501 | } | |
502 | ||
503 | if (!cb->subbuf_start) | |
504 | cb->subbuf_start = subbuf_start_default_callback; | |
505 | if (!cb->buf_mapped) | |
506 | cb->buf_mapped = buf_mapped_default_callback; | |
507 | if (!cb->buf_unmapped) | |
508 | cb->buf_unmapped = buf_unmapped_default_callback; | |
509 | if (!cb->create_buf_file) | |
510 | cb->create_buf_file = create_buf_file_default_callback; | |
511 | if (!cb->remove_buf_file) | |
512 | cb->remove_buf_file = remove_buf_file_default_callback; | |
513 | chan->cb = cb; | |
514 | } | |
515 | ||
23c88752 | 516 | /** |
23c88752 MD |
517 | * relay_hotcpu_callback - CPU hotplug callback |
518 | * @nb: notifier block | |
519 | * @action: hotplug action to take | |
520 | * @hcpu: CPU number | |
521 | * | |
05fb6bf0 | 522 | * Returns the success/failure of the operation. (%NOTIFY_OK, %NOTIFY_BAD) |
23c88752 | 523 | */ |
0db0628d | 524 | static int relay_hotcpu_callback(struct notifier_block *nb, |
23c88752 MD |
525 | unsigned long action, |
526 | void *hcpu) | |
527 | { | |
528 | unsigned int hotcpu = (unsigned long)hcpu; | |
529 | struct rchan *chan; | |
017c59c0 | 530 | struct rchan_buf *buf; |
23c88752 MD |
531 | |
532 | switch(action) { | |
533 | case CPU_UP_PREPARE: | |
8bb78442 | 534 | case CPU_UP_PREPARE_FROZEN: |
23c88752 MD |
535 | mutex_lock(&relay_channels_mutex); |
536 | list_for_each_entry(chan, &relay_channels, list) { | |
017c59c0 | 537 | if ((buf = *per_cpu_ptr(chan->buf, hotcpu))) |
23c88752 | 538 | continue; |
017c59c0 AG |
539 | buf = relay_open_buf(chan, hotcpu); |
540 | if (!buf) { | |
23c88752 MD |
541 | printk(KERN_ERR |
542 | "relay_hotcpu_callback: cpu %d buffer " | |
543 | "creation failed\n", hotcpu); | |
544 | mutex_unlock(&relay_channels_mutex); | |
80b5184c | 545 | return notifier_from_errno(-ENOMEM); |
23c88752 | 546 | } |
017c59c0 | 547 | *per_cpu_ptr(chan->buf, hotcpu) = buf; |
23c88752 MD |
548 | } |
549 | mutex_unlock(&relay_channels_mutex); | |
550 | break; | |
551 | case CPU_DEAD: | |
8bb78442 | 552 | case CPU_DEAD_FROZEN: |
23c88752 MD |
553 | /* No need to flush the cpu : will be flushed upon |
554 | * final relay_flush() call. */ | |
555 | break; | |
556 | } | |
557 | return NOTIFY_OK; | |
558 | } | |
559 | ||
b86ff981 JA |
560 | /** |
561 | * relay_open - create a new relay channel | |
20d8b67c EGM |
562 | * @base_filename: base name of files to create, %NULL for buffering only |
563 | * @parent: dentry of parent directory, %NULL for root directory or buffer | |
b86ff981 JA |
564 | * @subbuf_size: size of sub-buffers |
565 | * @n_subbufs: number of sub-buffers | |
566 | * @cb: client callback functions | |
23c88752 | 567 | * @private_data: user-defined data |
b86ff981 | 568 | * |
4c78a663 | 569 | * Returns channel pointer if successful, %NULL otherwise. |
b86ff981 JA |
570 | * |
571 | * Creates a channel buffer for each cpu using the sizes and | |
572 | * attributes specified. The created channel buffer files | |
573 | * will be named base_filename0...base_filenameN-1. File | |
72fd4a35 | 574 | * permissions will be %S_IRUSR. |
59dbb2a0 AG |
575 | * |
576 | * If opening a buffer (@parent = NULL) that you later wish to register | |
577 | * in a filesystem, call relay_late_setup_files() once the @parent dentry | |
578 | * is available. | |
b86ff981 JA |
579 | */ |
580 | struct rchan *relay_open(const char *base_filename, | |
581 | struct dentry *parent, | |
582 | size_t subbuf_size, | |
583 | size_t n_subbufs, | |
23c88752 MD |
584 | struct rchan_callbacks *cb, |
585 | void *private_data) | |
b86ff981 JA |
586 | { |
587 | unsigned int i; | |
588 | struct rchan *chan; | |
017c59c0 | 589 | struct rchan_buf *buf; |
b86ff981 JA |
590 | |
591 | if (!(subbuf_size && n_subbufs)) | |
592 | return NULL; | |
f6302f1b DC |
593 | if (subbuf_size > UINT_MAX / n_subbufs) |
594 | return NULL; | |
b86ff981 | 595 | |
cd861280 | 596 | chan = kzalloc(sizeof(struct rchan), GFP_KERNEL); |
b86ff981 JA |
597 | if (!chan) |
598 | return NULL; | |
599 | ||
017c59c0 | 600 | chan->buf = alloc_percpu(struct rchan_buf *); |
b86ff981 JA |
601 | chan->version = RELAYFS_CHANNEL_VERSION; |
602 | chan->n_subbufs = n_subbufs; | |
603 | chan->subbuf_size = subbuf_size; | |
a05342cb | 604 | chan->alloc_size = PAGE_ALIGN(subbuf_size * n_subbufs); |
23c88752 MD |
605 | chan->parent = parent; |
606 | chan->private_data = private_data; | |
20d8b67c EGM |
607 | if (base_filename) { |
608 | chan->has_base_filename = 1; | |
609 | strlcpy(chan->base_filename, base_filename, NAME_MAX); | |
610 | } | |
b86ff981 JA |
611 | setup_callbacks(chan, cb); |
612 | kref_init(&chan->kref); | |
613 | ||
23c88752 | 614 | mutex_lock(&relay_channels_mutex); |
b86ff981 | 615 | for_each_online_cpu(i) { |
017c59c0 AG |
616 | buf = relay_open_buf(chan, i); |
617 | if (!buf) | |
b86ff981 | 618 | goto free_bufs; |
017c59c0 | 619 | *per_cpu_ptr(chan->buf, i) = buf; |
b86ff981 | 620 | } |
23c88752 MD |
621 | list_add(&chan->list, &relay_channels); |
622 | mutex_unlock(&relay_channels_mutex); | |
b86ff981 | 623 | |
b86ff981 JA |
624 | return chan; |
625 | ||
626 | free_bufs: | |
98ba4031 | 627 | for_each_possible_cpu(i) { |
017c59c0 AG |
628 | if ((buf = *per_cpu_ptr(chan->buf, i))) |
629 | relay_close_buf(buf); | |
b86ff981 | 630 | } |
b86ff981 | 631 | |
b86ff981 | 632 | kref_put(&chan->kref, relay_destroy_channel); |
23c88752 | 633 | mutex_unlock(&relay_channels_mutex); |
ba62bafe | 634 | kfree(chan); |
b86ff981 JA |
635 | return NULL; |
636 | } | |
637 | EXPORT_SYMBOL_GPL(relay_open); | |
638 | ||
20d8b67c EGM |
639 | struct rchan_percpu_buf_dispatcher { |
640 | struct rchan_buf *buf; | |
641 | struct dentry *dentry; | |
642 | }; | |
643 | ||
644 | /* Called in atomic context. */ | |
645 | static void __relay_set_buf_dentry(void *info) | |
646 | { | |
647 | struct rchan_percpu_buf_dispatcher *p = info; | |
648 | ||
649 | relay_set_buf_dentry(p->buf, p->dentry); | |
650 | } | |
651 | ||
652 | /** | |
653 | * relay_late_setup_files - triggers file creation | |
654 | * @chan: channel to operate on | |
655 | * @base_filename: base name of files to create | |
656 | * @parent: dentry of parent directory, %NULL for root directory | |
657 | * | |
658 | * Returns 0 if successful, non-zero otherwise. | |
659 | * | |
59dbb2a0 AG |
660 | * Use to setup files for a previously buffer-only channel created |
661 | * by relay_open() with a NULL parent dentry. | |
662 | * | |
663 | * For example, this is useful for perfomring early tracing in kernel, | |
664 | * before VFS is up and then exposing the early results once the dentry | |
665 | * is available. | |
20d8b67c EGM |
666 | */ |
667 | int relay_late_setup_files(struct rchan *chan, | |
668 | const char *base_filename, | |
669 | struct dentry *parent) | |
670 | { | |
671 | int err = 0; | |
672 | unsigned int i, curr_cpu; | |
673 | unsigned long flags; | |
674 | struct dentry *dentry; | |
017c59c0 | 675 | struct rchan_buf *buf; |
20d8b67c EGM |
676 | struct rchan_percpu_buf_dispatcher disp; |
677 | ||
678 | if (!chan || !base_filename) | |
679 | return -EINVAL; | |
680 | ||
681 | strlcpy(chan->base_filename, base_filename, NAME_MAX); | |
682 | ||
683 | mutex_lock(&relay_channels_mutex); | |
684 | /* Is chan already set up? */ | |
b786c6a9 JS |
685 | if (unlikely(chan->has_base_filename)) { |
686 | mutex_unlock(&relay_channels_mutex); | |
20d8b67c | 687 | return -EEXIST; |
b786c6a9 | 688 | } |
20d8b67c EGM |
689 | chan->has_base_filename = 1; |
690 | chan->parent = parent; | |
59dbb2a0 AG |
691 | |
692 | if (chan->is_global) { | |
693 | err = -EINVAL; | |
017c59c0 AG |
694 | buf = *per_cpu_ptr(chan->buf, 0); |
695 | if (!WARN_ON_ONCE(!buf)) { | |
696 | dentry = relay_create_buf_file(chan, buf, 0); | |
59dbb2a0 | 697 | if (dentry && !WARN_ON_ONCE(!chan->is_global)) { |
017c59c0 | 698 | relay_set_buf_dentry(buf, dentry); |
59dbb2a0 AG |
699 | err = 0; |
700 | } | |
701 | } | |
702 | mutex_unlock(&relay_channels_mutex); | |
703 | return err; | |
704 | } | |
705 | ||
20d8b67c EGM |
706 | curr_cpu = get_cpu(); |
707 | /* | |
708 | * The CPU hotplug notifier ran before us and created buffers with | |
709 | * no files associated. So it's safe to call relay_setup_buf_file() | |
710 | * on all currently online CPUs. | |
711 | */ | |
712 | for_each_online_cpu(i) { | |
017c59c0 AG |
713 | buf = *per_cpu_ptr(chan->buf, i); |
714 | if (unlikely(!buf)) { | |
7a51cffb | 715 | WARN_ONCE(1, KERN_ERR "CPU has no buffer!\n"); |
20d8b67c EGM |
716 | err = -EINVAL; |
717 | break; | |
718 | } | |
719 | ||
017c59c0 | 720 | dentry = relay_create_buf_file(chan, buf, i); |
20d8b67c EGM |
721 | if (unlikely(!dentry)) { |
722 | err = -EINVAL; | |
723 | break; | |
724 | } | |
725 | ||
726 | if (curr_cpu == i) { | |
727 | local_irq_save(flags); | |
017c59c0 | 728 | relay_set_buf_dentry(buf, dentry); |
20d8b67c EGM |
729 | local_irq_restore(flags); |
730 | } else { | |
017c59c0 | 731 | disp.buf = buf; |
20d8b67c EGM |
732 | disp.dentry = dentry; |
733 | smp_mb(); | |
734 | /* relay_channels_mutex must be held, so wait. */ | |
735 | err = smp_call_function_single(i, | |
736 | __relay_set_buf_dentry, | |
737 | &disp, 1); | |
738 | } | |
739 | if (unlikely(err)) | |
740 | break; | |
741 | } | |
742 | put_cpu(); | |
743 | mutex_unlock(&relay_channels_mutex); | |
744 | ||
745 | return err; | |
746 | } | |
59dbb2a0 | 747 | EXPORT_SYMBOL_GPL(relay_late_setup_files); |
20d8b67c | 748 | |
b86ff981 JA |
749 | /** |
750 | * relay_switch_subbuf - switch to a new sub-buffer | |
751 | * @buf: channel buffer | |
752 | * @length: size of current event | |
753 | * | |
754 | * Returns either the length passed in or 0 if full. | |
755 | * | |
756 | * Performs sub-buffer-switch tasks such as invoking callbacks, | |
757 | * updating padding counts, waking up readers, etc. | |
758 | */ | |
759 | size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length) | |
760 | { | |
761 | void *old, *new; | |
762 | size_t old_subbuf, new_subbuf; | |
763 | ||
764 | if (unlikely(length > buf->chan->subbuf_size)) | |
765 | goto toobig; | |
766 | ||
767 | if (buf->offset != buf->chan->subbuf_size + 1) { | |
768 | buf->prev_padding = buf->chan->subbuf_size - buf->offset; | |
769 | old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; | |
770 | buf->padding[old_subbuf] = buf->prev_padding; | |
771 | buf->subbufs_produced++; | |
20d8b67c | 772 | if (buf->dentry) |
7682c918 | 773 | d_inode(buf->dentry)->i_size += |
20d8b67c EGM |
774 | buf->chan->subbuf_size - |
775 | buf->padding[old_subbuf]; | |
776 | else | |
777 | buf->early_bytes += buf->chan->subbuf_size - | |
778 | buf->padding[old_subbuf]; | |
221415d7 | 779 | smp_mb(); |
7c9cb383 TZ |
780 | if (waitqueue_active(&buf->read_wait)) |
781 | /* | |
782 | * Calling wake_up_interruptible() from here | |
783 | * will deadlock if we happen to be logging | |
784 | * from the scheduler (trying to re-grab | |
785 | * rq->lock), so defer it. | |
786 | */ | |
74019224 | 787 | mod_timer(&buf->timer, jiffies + 1); |
b86ff981 JA |
788 | } |
789 | ||
790 | old = buf->data; | |
791 | new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; | |
792 | new = buf->start + new_subbuf * buf->chan->subbuf_size; | |
793 | buf->offset = 0; | |
794 | if (!buf->chan->cb->subbuf_start(buf, new, old, buf->prev_padding)) { | |
795 | buf->offset = buf->chan->subbuf_size + 1; | |
796 | return 0; | |
797 | } | |
798 | buf->data = new; | |
799 | buf->padding[new_subbuf] = 0; | |
800 | ||
801 | if (unlikely(length + buf->offset > buf->chan->subbuf_size)) | |
802 | goto toobig; | |
803 | ||
804 | return length; | |
805 | ||
806 | toobig: | |
807 | buf->chan->last_toobig = length; | |
808 | return 0; | |
809 | } | |
810 | EXPORT_SYMBOL_GPL(relay_switch_subbuf); | |
811 | ||
812 | /** | |
813 | * relay_subbufs_consumed - update the buffer's sub-buffers-consumed count | |
814 | * @chan: the channel | |
815 | * @cpu: the cpu associated with the channel buffer to update | |
816 | * @subbufs_consumed: number of sub-buffers to add to current buf's count | |
817 | * | |
818 | * Adds to the channel buffer's consumed sub-buffer count. | |
819 | * subbufs_consumed should be the number of sub-buffers newly consumed, | |
820 | * not the total consumed. | |
821 | * | |
72fd4a35 | 822 | * NOTE. Kernel clients don't need to call this function if the channel |
b86ff981 JA |
823 | * mode is 'overwrite'. |
824 | */ | |
825 | void relay_subbufs_consumed(struct rchan *chan, | |
826 | unsigned int cpu, | |
827 | size_t subbufs_consumed) | |
828 | { | |
829 | struct rchan_buf *buf; | |
830 | ||
831 | if (!chan) | |
832 | return; | |
833 | ||
017c59c0 AG |
834 | buf = *per_cpu_ptr(chan->buf, cpu); |
835 | if (cpu >= NR_CPUS || !buf || subbufs_consumed > chan->n_subbufs) | |
b86ff981 JA |
836 | return; |
837 | ||
2c53d910 | 838 | if (subbufs_consumed > buf->subbufs_produced - buf->subbufs_consumed) |
b86ff981 | 839 | buf->subbufs_consumed = buf->subbufs_produced; |
2c53d910 AS |
840 | else |
841 | buf->subbufs_consumed += subbufs_consumed; | |
b86ff981 JA |
842 | } |
843 | EXPORT_SYMBOL_GPL(relay_subbufs_consumed); | |
844 | ||
845 | /** | |
846 | * relay_close - close the channel | |
847 | * @chan: the channel | |
848 | * | |
849 | * Closes all channel buffers and frees the channel. | |
850 | */ | |
851 | void relay_close(struct rchan *chan) | |
852 | { | |
017c59c0 | 853 | struct rchan_buf *buf; |
b86ff981 | 854 | unsigned int i; |
b86ff981 JA |
855 | |
856 | if (!chan) | |
857 | return; | |
858 | ||
23c88752 | 859 | mutex_lock(&relay_channels_mutex); |
017c59c0 AG |
860 | if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0))) |
861 | relay_close_buf(buf); | |
23c88752 MD |
862 | else |
863 | for_each_possible_cpu(i) | |
017c59c0 AG |
864 | if ((buf = *per_cpu_ptr(chan->buf, i))) |
865 | relay_close_buf(buf); | |
b86ff981 JA |
866 | |
867 | if (chan->last_toobig) | |
868 | printk(KERN_WARNING "relay: one or more items not logged " | |
869 | "[item size (%Zd) > sub-buffer size (%Zd)]\n", | |
870 | chan->last_toobig, chan->subbuf_size); | |
871 | ||
23c88752 | 872 | list_del(&chan->list); |
b86ff981 | 873 | kref_put(&chan->kref, relay_destroy_channel); |
23c88752 | 874 | mutex_unlock(&relay_channels_mutex); |
b86ff981 JA |
875 | } |
876 | EXPORT_SYMBOL_GPL(relay_close); | |
877 | ||
878 | /** | |
879 | * relay_flush - close the channel | |
880 | * @chan: the channel | |
881 | * | |
4c78a663 | 882 | * Flushes all channel buffers, i.e. forces buffer switch. |
b86ff981 JA |
883 | */ |
884 | void relay_flush(struct rchan *chan) | |
885 | { | |
017c59c0 | 886 | struct rchan_buf *buf; |
b86ff981 | 887 | unsigned int i; |
b86ff981 JA |
888 | |
889 | if (!chan) | |
890 | return; | |
891 | ||
017c59c0 AG |
892 | if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0))) { |
893 | relay_switch_subbuf(buf, 0); | |
23c88752 | 894 | return; |
b86ff981 | 895 | } |
23c88752 MD |
896 | |
897 | mutex_lock(&relay_channels_mutex); | |
898 | for_each_possible_cpu(i) | |
017c59c0 AG |
899 | if ((buf = *per_cpu_ptr(chan->buf, i))) |
900 | relay_switch_subbuf(buf, 0); | |
23c88752 | 901 | mutex_unlock(&relay_channels_mutex); |
b86ff981 JA |
902 | } |
903 | EXPORT_SYMBOL_GPL(relay_flush); | |
904 | ||
905 | /** | |
906 | * relay_file_open - open file op for relay files | |
907 | * @inode: the inode | |
908 | * @filp: the file | |
909 | * | |
910 | * Increments the channel buffer refcount. | |
911 | */ | |
912 | static int relay_file_open(struct inode *inode, struct file *filp) | |
913 | { | |
8e18e294 | 914 | struct rchan_buf *buf = inode->i_private; |
b86ff981 JA |
915 | kref_get(&buf->kref); |
916 | filp->private_data = buf; | |
917 | ||
37529fe9 | 918 | return nonseekable_open(inode, filp); |
b86ff981 JA |
919 | } |
920 | ||
921 | /** | |
922 | * relay_file_mmap - mmap file op for relay files | |
923 | * @filp: the file | |
924 | * @vma: the vma describing what to map | |
925 | * | |
72fd4a35 | 926 | * Calls upon relay_mmap_buf() to map the file into user space. |
b86ff981 JA |
927 | */ |
928 | static int relay_file_mmap(struct file *filp, struct vm_area_struct *vma) | |
929 | { | |
930 | struct rchan_buf *buf = filp->private_data; | |
931 | return relay_mmap_buf(buf, vma); | |
932 | } | |
933 | ||
934 | /** | |
935 | * relay_file_poll - poll file op for relay files | |
936 | * @filp: the file | |
937 | * @wait: poll table | |
938 | * | |
939 | * Poll implemention. | |
940 | */ | |
941 | static unsigned int relay_file_poll(struct file *filp, poll_table *wait) | |
942 | { | |
943 | unsigned int mask = 0; | |
944 | struct rchan_buf *buf = filp->private_data; | |
945 | ||
946 | if (buf->finalized) | |
947 | return POLLERR; | |
948 | ||
949 | if (filp->f_mode & FMODE_READ) { | |
950 | poll_wait(filp, &buf->read_wait, wait); | |
951 | if (!relay_buf_empty(buf)) | |
952 | mask |= POLLIN | POLLRDNORM; | |
953 | } | |
954 | ||
955 | return mask; | |
956 | } | |
957 | ||
958 | /** | |
959 | * relay_file_release - release file op for relay files | |
960 | * @inode: the inode | |
961 | * @filp: the file | |
962 | * | |
963 | * Decrements the channel refcount, as the filesystem is | |
964 | * no longer using it. | |
965 | */ | |
966 | static int relay_file_release(struct inode *inode, struct file *filp) | |
967 | { | |
968 | struct rchan_buf *buf = filp->private_data; | |
969 | kref_put(&buf->kref, relay_remove_buf); | |
970 | ||
971 | return 0; | |
972 | } | |
973 | ||
4c78a663 | 974 | /* |
b86ff981 JA |
975 | * relay_file_read_consume - update the consumed count for the buffer |
976 | */ | |
977 | static void relay_file_read_consume(struct rchan_buf *buf, | |
978 | size_t read_pos, | |
979 | size_t bytes_consumed) | |
980 | { | |
981 | size_t subbuf_size = buf->chan->subbuf_size; | |
982 | size_t n_subbufs = buf->chan->n_subbufs; | |
983 | size_t read_subbuf; | |
984 | ||
32194450 TZ |
985 | if (buf->subbufs_produced == buf->subbufs_consumed && |
986 | buf->offset == buf->bytes_consumed) | |
987 | return; | |
988 | ||
b86ff981 JA |
989 | if (buf->bytes_consumed + bytes_consumed > subbuf_size) { |
990 | relay_subbufs_consumed(buf->chan, buf->cpu, 1); | |
991 | buf->bytes_consumed = 0; | |
992 | } | |
993 | ||
994 | buf->bytes_consumed += bytes_consumed; | |
a66e356c MH |
995 | if (!read_pos) |
996 | read_subbuf = buf->subbufs_consumed % n_subbufs; | |
997 | else | |
998 | read_subbuf = read_pos / buf->chan->subbuf_size; | |
b86ff981 JA |
999 | if (buf->bytes_consumed + buf->padding[read_subbuf] == subbuf_size) { |
1000 | if ((read_subbuf == buf->subbufs_produced % n_subbufs) && | |
1001 | (buf->offset == subbuf_size)) | |
1002 | return; | |
1003 | relay_subbufs_consumed(buf->chan, buf->cpu, 1); | |
1004 | buf->bytes_consumed = 0; | |
1005 | } | |
1006 | } | |
1007 | ||
4c78a663 | 1008 | /* |
b86ff981 JA |
1009 | * relay_file_read_avail - boolean, are there unconsumed bytes available? |
1010 | */ | |
1011 | static int relay_file_read_avail(struct rchan_buf *buf, size_t read_pos) | |
1012 | { | |
b86ff981 JA |
1013 | size_t subbuf_size = buf->chan->subbuf_size; |
1014 | size_t n_subbufs = buf->chan->n_subbufs; | |
221415d7 JA |
1015 | size_t produced = buf->subbufs_produced; |
1016 | size_t consumed = buf->subbufs_consumed; | |
b86ff981 | 1017 | |
221415d7 | 1018 | relay_file_read_consume(buf, read_pos, 0); |
b86ff981 | 1019 | |
32194450 TZ |
1020 | consumed = buf->subbufs_consumed; |
1021 | ||
221415d7 JA |
1022 | if (unlikely(buf->offset > subbuf_size)) { |
1023 | if (produced == consumed) | |
1024 | return 0; | |
1025 | return 1; | |
b86ff981 JA |
1026 | } |
1027 | ||
221415d7 | 1028 | if (unlikely(produced - consumed >= n_subbufs)) { |
a66e356c | 1029 | consumed = produced - n_subbufs + 1; |
221415d7 | 1030 | buf->subbufs_consumed = consumed; |
a66e356c | 1031 | buf->bytes_consumed = 0; |
221415d7 | 1032 | } |
1bfbc608 | 1033 | |
221415d7 JA |
1034 | produced = (produced % n_subbufs) * subbuf_size + buf->offset; |
1035 | consumed = (consumed % n_subbufs) * subbuf_size + buf->bytes_consumed; | |
1036 | ||
1037 | if (consumed > produced) | |
1038 | produced += n_subbufs * subbuf_size; | |
1bfbc608 | 1039 | |
32194450 TZ |
1040 | if (consumed == produced) { |
1041 | if (buf->offset == subbuf_size && | |
1042 | buf->subbufs_produced > buf->subbufs_consumed) | |
1043 | return 1; | |
b86ff981 | 1044 | return 0; |
32194450 | 1045 | } |
b86ff981 | 1046 | |
b86ff981 JA |
1047 | return 1; |
1048 | } | |
1049 | ||
1050 | /** | |
1051 | * relay_file_read_subbuf_avail - return bytes available in sub-buffer | |
4c78a663 RD |
1052 | * @read_pos: file read position |
1053 | * @buf: relay channel buffer | |
b86ff981 JA |
1054 | */ |
1055 | static size_t relay_file_read_subbuf_avail(size_t read_pos, | |
1056 | struct rchan_buf *buf) | |
1057 | { | |
1058 | size_t padding, avail = 0; | |
1059 | size_t read_subbuf, read_offset, write_subbuf, write_offset; | |
1060 | size_t subbuf_size = buf->chan->subbuf_size; | |
1061 | ||
1062 | write_subbuf = (buf->data - buf->start) / subbuf_size; | |
1063 | write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset; | |
1064 | read_subbuf = read_pos / subbuf_size; | |
1065 | read_offset = read_pos % subbuf_size; | |
1066 | padding = buf->padding[read_subbuf]; | |
1067 | ||
1068 | if (read_subbuf == write_subbuf) { | |
1069 | if (read_offset + padding < write_offset) | |
1070 | avail = write_offset - (read_offset + padding); | |
1071 | } else | |
1072 | avail = (subbuf_size - padding) - read_offset; | |
1073 | ||
1074 | return avail; | |
1075 | } | |
1076 | ||
1077 | /** | |
1078 | * relay_file_read_start_pos - find the first available byte to read | |
4c78a663 RD |
1079 | * @read_pos: file read position |
1080 | * @buf: relay channel buffer | |
b86ff981 | 1081 | * |
72fd4a35 | 1082 | * If the @read_pos is in the middle of padding, return the |
b86ff981 JA |
1083 | * position of the first actually available byte, otherwise |
1084 | * return the original value. | |
1085 | */ | |
1086 | static size_t relay_file_read_start_pos(size_t read_pos, | |
1087 | struct rchan_buf *buf) | |
1088 | { | |
1089 | size_t read_subbuf, padding, padding_start, padding_end; | |
1090 | size_t subbuf_size = buf->chan->subbuf_size; | |
1091 | size_t n_subbufs = buf->chan->n_subbufs; | |
8d62fdeb | 1092 | size_t consumed = buf->subbufs_consumed % n_subbufs; |
b86ff981 | 1093 | |
8d62fdeb DW |
1094 | if (!read_pos) |
1095 | read_pos = consumed * subbuf_size + buf->bytes_consumed; | |
b86ff981 JA |
1096 | read_subbuf = read_pos / subbuf_size; |
1097 | padding = buf->padding[read_subbuf]; | |
1098 | padding_start = (read_subbuf + 1) * subbuf_size - padding; | |
1099 | padding_end = (read_subbuf + 1) * subbuf_size; | |
1100 | if (read_pos >= padding_start && read_pos < padding_end) { | |
1101 | read_subbuf = (read_subbuf + 1) % n_subbufs; | |
1102 | read_pos = read_subbuf * subbuf_size; | |
1103 | } | |
1104 | ||
1105 | return read_pos; | |
1106 | } | |
1107 | ||
1108 | /** | |
1109 | * relay_file_read_end_pos - return the new read position | |
4c78a663 RD |
1110 | * @read_pos: file read position |
1111 | * @buf: relay channel buffer | |
1112 | * @count: number of bytes to be read | |
b86ff981 JA |
1113 | */ |
1114 | static size_t relay_file_read_end_pos(struct rchan_buf *buf, | |
1115 | size_t read_pos, | |
1116 | size_t count) | |
1117 | { | |
1118 | size_t read_subbuf, padding, end_pos; | |
1119 | size_t subbuf_size = buf->chan->subbuf_size; | |
1120 | size_t n_subbufs = buf->chan->n_subbufs; | |
1121 | ||
1122 | read_subbuf = read_pos / subbuf_size; | |
1123 | padding = buf->padding[read_subbuf]; | |
1124 | if (read_pos % subbuf_size + count + padding == subbuf_size) | |
1125 | end_pos = (read_subbuf + 1) * subbuf_size; | |
1126 | else | |
1127 | end_pos = read_pos + count; | |
1128 | if (end_pos >= subbuf_size * n_subbufs) | |
1129 | end_pos = 0; | |
1130 | ||
1131 | return end_pos; | |
1132 | } | |
1133 | ||
4c78a663 | 1134 | /* |
6dac40a7 | 1135 | * subbuf_read_actor - read up to one subbuf's worth of data |
b86ff981 | 1136 | */ |
6dac40a7 TZ |
1137 | static int subbuf_read_actor(size_t read_start, |
1138 | struct rchan_buf *buf, | |
1139 | size_t avail, | |
8359f689 | 1140 | read_descriptor_t *desc) |
b86ff981 | 1141 | { |
b86ff981 | 1142 | void *from; |
6dac40a7 | 1143 | int ret = 0; |
b86ff981 JA |
1144 | |
1145 | from = buf->start + read_start; | |
6dac40a7 | 1146 | ret = avail; |
ba2397ef | 1147 | if (copy_to_user(desc->arg.buf, from, avail)) { |
6dac40a7 TZ |
1148 | desc->error = -EFAULT; |
1149 | ret = 0; | |
b86ff981 | 1150 | } |
6dac40a7 TZ |
1151 | desc->arg.data += ret; |
1152 | desc->written += ret; | |
1153 | desc->count -= ret; | |
1154 | ||
b86ff981 JA |
1155 | return ret; |
1156 | } | |
1157 | ||
6dac40a7 TZ |
1158 | typedef int (*subbuf_actor_t) (size_t read_start, |
1159 | struct rchan_buf *buf, | |
1160 | size_t avail, | |
8359f689 | 1161 | read_descriptor_t *desc); |
6dac40a7 | 1162 | |
4c78a663 | 1163 | /* |
6dac40a7 TZ |
1164 | * relay_file_read_subbufs - read count bytes, bridging subbuf boundaries |
1165 | */ | |
192636ad AM |
1166 | static ssize_t relay_file_read_subbufs(struct file *filp, loff_t *ppos, |
1167 | subbuf_actor_t subbuf_actor, | |
192636ad | 1168 | read_descriptor_t *desc) |
221415d7 | 1169 | { |
6dac40a7 TZ |
1170 | struct rchan_buf *buf = filp->private_data; |
1171 | size_t read_start, avail; | |
6dac40a7 | 1172 | int ret; |
221415d7 | 1173 | |
ba2397ef | 1174 | if (!desc->count) |
221415d7 JA |
1175 | return 0; |
1176 | ||
5955102c | 1177 | inode_lock(file_inode(filp)); |
221415d7 | 1178 | do { |
6dac40a7 TZ |
1179 | if (!relay_file_read_avail(buf, *ppos)) |
1180 | break; | |
1181 | ||
1182 | read_start = relay_file_read_start_pos(*ppos, buf); | |
1183 | avail = relay_file_read_subbuf_avail(read_start, buf); | |
1184 | if (!avail) | |
221415d7 | 1185 | break; |
221415d7 | 1186 | |
ba2397ef | 1187 | avail = min(desc->count, avail); |
8359f689 | 1188 | ret = subbuf_actor(read_start, buf, avail, desc); |
ba2397ef | 1189 | if (desc->error < 0) |
6dac40a7 TZ |
1190 | break; |
1191 | ||
1192 | if (ret) { | |
1193 | relay_file_read_consume(buf, read_start, ret); | |
1194 | *ppos = relay_file_read_end_pos(buf, read_start, ret); | |
1195 | } | |
ba2397ef | 1196 | } while (desc->count && ret); |
5955102c | 1197 | inode_unlock(file_inode(filp)); |
6dac40a7 | 1198 | |
ba2397ef | 1199 | return desc->written; |
6dac40a7 TZ |
1200 | } |
1201 | ||
1202 | static ssize_t relay_file_read(struct file *filp, | |
1203 | char __user *buffer, | |
1204 | size_t count, | |
1205 | loff_t *ppos) | |
1206 | { | |
ba2397ef AV |
1207 | read_descriptor_t desc; |
1208 | desc.written = 0; | |
1209 | desc.count = count; | |
1210 | desc.arg.buf = buffer; | |
1211 | desc.error = 0; | |
8359f689 | 1212 | return relay_file_read_subbufs(filp, ppos, subbuf_read_actor, &desc); |
6dac40a7 TZ |
1213 | } |
1214 | ||
1db60cf2 JA |
1215 | static void relay_consume_bytes(struct rchan_buf *rbuf, int bytes_consumed) |
1216 | { | |
1217 | rbuf->bytes_consumed += bytes_consumed; | |
1218 | ||
1219 | if (rbuf->bytes_consumed >= rbuf->chan->subbuf_size) { | |
1220 | relay_subbufs_consumed(rbuf->chan, rbuf->cpu, 1); | |
1221 | rbuf->bytes_consumed %= rbuf->chan->subbuf_size; | |
1222 | } | |
1223 | } | |
1224 | ||
ebf99093 TZ |
1225 | static void relay_pipe_buf_release(struct pipe_inode_info *pipe, |
1226 | struct pipe_buffer *buf) | |
6dac40a7 | 1227 | { |
ebf99093 TZ |
1228 | struct rchan_buf *rbuf; |
1229 | ||
1230 | rbuf = (struct rchan_buf *)page_private(buf->page); | |
1db60cf2 | 1231 | relay_consume_bytes(rbuf, buf->private); |
ebf99093 TZ |
1232 | } |
1233 | ||
28dfef8f | 1234 | static const struct pipe_buf_operations relay_pipe_buf_ops = { |
ebf99093 | 1235 | .can_merge = 0, |
cac36bb0 | 1236 | .confirm = generic_pipe_buf_confirm, |
ebf99093 TZ |
1237 | .release = relay_pipe_buf_release, |
1238 | .steal = generic_pipe_buf_steal, | |
1239 | .get = generic_pipe_buf_get, | |
1240 | }; | |
1241 | ||
5eb7f9fa JA |
1242 | static void relay_page_release(struct splice_pipe_desc *spd, unsigned int i) |
1243 | { | |
1244 | } | |
1245 | ||
d3f35d98 | 1246 | /* |
ebf99093 TZ |
1247 | * subbuf_splice_actor - splice up to one subbuf's worth of data |
1248 | */ | |
5f1664f9 | 1249 | static ssize_t subbuf_splice_actor(struct file *in, |
ebf99093 TZ |
1250 | loff_t *ppos, |
1251 | struct pipe_inode_info *pipe, | |
1252 | size_t len, | |
1253 | unsigned int flags, | |
1254 | int *nonpad_ret) | |
1255 | { | |
5f1664f9 | 1256 | unsigned int pidx, poff, total_len, subbuf_pages, nr_pages; |
ebf99093 TZ |
1257 | struct rchan_buf *rbuf = in->private_data; |
1258 | unsigned int subbuf_size = rbuf->chan->subbuf_size; | |
24da24de TZ |
1259 | uint64_t pos = (uint64_t) *ppos; |
1260 | uint32_t alloc_size = (uint32_t) rbuf->chan->alloc_size; | |
1261 | size_t read_start = (size_t) do_div(pos, alloc_size); | |
ebf99093 TZ |
1262 | size_t read_subbuf = read_start / subbuf_size; |
1263 | size_t padding = rbuf->padding[read_subbuf]; | |
1264 | size_t nonpad_end = read_subbuf * subbuf_size + subbuf_size - padding; | |
35f3d14d JA |
1265 | struct page *pages[PIPE_DEF_BUFFERS]; |
1266 | struct partial_page partial[PIPE_DEF_BUFFERS]; | |
1db60cf2 JA |
1267 | struct splice_pipe_desc spd = { |
1268 | .pages = pages, | |
1269 | .nr_pages = 0, | |
047fe360 | 1270 | .nr_pages_max = PIPE_DEF_BUFFERS, |
1db60cf2 JA |
1271 | .partial = partial, |
1272 | .flags = flags, | |
1273 | .ops = &relay_pipe_buf_ops, | |
5eb7f9fa | 1274 | .spd_release = relay_page_release, |
1db60cf2 | 1275 | }; |
5f1664f9 | 1276 | ssize_t ret; |
ebf99093 TZ |
1277 | |
1278 | if (rbuf->subbufs_produced == rbuf->subbufs_consumed) | |
1279 | return 0; | |
35f3d14d JA |
1280 | if (splice_grow_spd(pipe, &spd)) |
1281 | return -ENOMEM; | |
ebf99093 | 1282 | |
1db60cf2 JA |
1283 | /* |
1284 | * Adjust read len, if longer than what is available | |
1285 | */ | |
1286 | if (len > (subbuf_size - read_start % subbuf_size)) | |
1287 | len = subbuf_size - read_start % subbuf_size; | |
ebf99093 TZ |
1288 | |
1289 | subbuf_pages = rbuf->chan->alloc_size >> PAGE_SHIFT; | |
1290 | pidx = (read_start / PAGE_SIZE) % subbuf_pages; | |
1291 | poff = read_start & ~PAGE_MASK; | |
a786c06d | 1292 | nr_pages = min_t(unsigned int, subbuf_pages, spd.nr_pages_max); |
ebf99093 | 1293 | |
16d54669 | 1294 | for (total_len = 0; spd.nr_pages < nr_pages; spd.nr_pages++) { |
1db60cf2 JA |
1295 | unsigned int this_len, this_end, private; |
1296 | unsigned int cur_pos = read_start + total_len; | |
ebf99093 | 1297 | |
1db60cf2 | 1298 | if (!len) |
ebf99093 | 1299 | break; |
ebf99093 | 1300 | |
1db60cf2 JA |
1301 | this_len = min_t(unsigned long, len, PAGE_SIZE - poff); |
1302 | private = this_len; | |
ebf99093 | 1303 | |
1db60cf2 JA |
1304 | spd.pages[spd.nr_pages] = rbuf->page_array[pidx]; |
1305 | spd.partial[spd.nr_pages].offset = poff; | |
ebf99093 | 1306 | |
1db60cf2 JA |
1307 | this_end = cur_pos + this_len; |
1308 | if (this_end >= nonpad_end) { | |
1309 | this_len = nonpad_end - cur_pos; | |
1310 | private = this_len + padding; | |
ebf99093 | 1311 | } |
1db60cf2 JA |
1312 | spd.partial[spd.nr_pages].len = this_len; |
1313 | spd.partial[spd.nr_pages].private = private; | |
ebf99093 | 1314 | |
1db60cf2 JA |
1315 | len -= this_len; |
1316 | total_len += this_len; | |
1317 | poff = 0; | |
1318 | pidx = (pidx + 1) % subbuf_pages; | |
ebf99093 | 1319 | |
1db60cf2 JA |
1320 | if (this_end >= nonpad_end) { |
1321 | spd.nr_pages++; | |
ebf99093 TZ |
1322 | break; |
1323 | } | |
ebf99093 TZ |
1324 | } |
1325 | ||
35f3d14d | 1326 | ret = 0; |
1db60cf2 | 1327 | if (!spd.nr_pages) |
35f3d14d | 1328 | goto out; |
ebf99093 | 1329 | |
1db60cf2 JA |
1330 | ret = *nonpad_ret = splice_to_pipe(pipe, &spd); |
1331 | if (ret < 0 || ret < total_len) | |
35f3d14d | 1332 | goto out; |
ebf99093 | 1333 | |
1db60cf2 JA |
1334 | if (read_start + ret == nonpad_end) |
1335 | ret += padding; | |
1336 | ||
35f3d14d | 1337 | out: |
047fe360 ED |
1338 | splice_shrink_spd(&spd); |
1339 | return ret; | |
ebf99093 TZ |
1340 | } |
1341 | ||
1342 | static ssize_t relay_file_splice_read(struct file *in, | |
1343 | loff_t *ppos, | |
1344 | struct pipe_inode_info *pipe, | |
1345 | size_t len, | |
1346 | unsigned int flags) | |
1347 | { | |
1348 | ssize_t spliced; | |
1349 | int ret; | |
1350 | int nonpad_ret = 0; | |
1351 | ||
1352 | ret = 0; | |
1353 | spliced = 0; | |
1354 | ||
a82c53a0 | 1355 | while (len && !spliced) { |
ebf99093 TZ |
1356 | ret = subbuf_splice_actor(in, ppos, pipe, len, flags, &nonpad_ret); |
1357 | if (ret < 0) | |
1358 | break; | |
1359 | else if (!ret) { | |
fbb5b7ae | 1360 | if (flags & SPLICE_F_NONBLOCK) |
ebf99093 | 1361 | ret = -EAGAIN; |
fbb5b7ae | 1362 | break; |
ebf99093 TZ |
1363 | } |
1364 | ||
1365 | *ppos += ret; | |
1366 | if (ret > len) | |
1367 | len = 0; | |
1368 | else | |
1369 | len -= ret; | |
1370 | spliced += nonpad_ret; | |
1371 | nonpad_ret = 0; | |
1372 | } | |
1373 | ||
1374 | if (spliced) | |
1375 | return spliced; | |
1376 | ||
1377 | return ret; | |
221415d7 JA |
1378 | } |
1379 | ||
15ad7cdc | 1380 | const struct file_operations relay_file_operations = { |
b86ff981 JA |
1381 | .open = relay_file_open, |
1382 | .poll = relay_file_poll, | |
1383 | .mmap = relay_file_mmap, | |
1384 | .read = relay_file_read, | |
1385 | .llseek = no_llseek, | |
1386 | .release = relay_file_release, | |
ebf99093 | 1387 | .splice_read = relay_file_splice_read, |
b86ff981 JA |
1388 | }; |
1389 | EXPORT_SYMBOL_GPL(relay_file_operations); | |
23c88752 MD |
1390 | |
1391 | static __init int relay_init(void) | |
1392 | { | |
1393 | ||
1394 | hotcpu_notifier(relay_hotcpu_callback, 0); | |
1395 | return 0; | |
1396 | } | |
1397 | ||
20d8b67c | 1398 | early_initcall(relay_init); |