Commit | Line | Data |
---|---|---|
b86ff981 JA |
1 | /* |
2 | * Public API and common code for kernel->userspace relay file support. | |
3 | * | |
0c1bc6b8 | 4 | * See Documentation/filesystems/relay.rst 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 | */ |
3fb3894b | 42 | static vm_fault_t relay_buf_fault(struct vm_fault *vmf) |
b86ff981 JA |
43 | { |
44 | struct page *page; | |
11bac800 | 45 | struct rchan_buf *buf = vmf->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 | * | |
c1e8d7c6 | 94 | * Caller should already have grabbed mmap_lock. |
b86ff981 | 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 | ||
88913bd8 | 166 | if (chan->n_subbufs > KMALLOC_MAX_SIZE / 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; | |
6da2ec56 KC |
172 | buf->padding = kmalloc_array(chan->n_subbufs, sizeof(size_t *), |
173 | GFP_KERNEL); | |
b86ff981 JA |
174 | if (!buf->padding) |
175 | goto free_buf; | |
176 | ||
221415d7 | 177 | buf->start = relay_alloc_buf(buf, &chan->alloc_size); |
b86ff981 JA |
178 | if (!buf->start) |
179 | goto free_buf; | |
180 | ||
181 | buf->chan = chan; | |
182 | kref_get(&buf->chan->kref); | |
183 | return buf; | |
184 | ||
185 | free_buf: | |
186 | kfree(buf->padding); | |
187 | kfree(buf); | |
188 | return NULL; | |
189 | } | |
190 | ||
191 | /** | |
192 | * relay_destroy_channel - free the channel struct | |
4c78a663 | 193 | * @kref: target kernel reference that contains the relay channel |
b86ff981 JA |
194 | * |
195 | * Should only be called from kref_put(). | |
196 | */ | |
01c55ed3 | 197 | static void relay_destroy_channel(struct kref *kref) |
b86ff981 JA |
198 | { |
199 | struct rchan *chan = container_of(kref, struct rchan, kref); | |
71e84329 | 200 | free_percpu(chan->buf); |
b86ff981 JA |
201 | kfree(chan); |
202 | } | |
203 | ||
204 | /** | |
205 | * relay_destroy_buf - destroy an rchan_buf struct and associated buffer | |
206 | * @buf: the buffer struct | |
207 | */ | |
01c55ed3 | 208 | static void relay_destroy_buf(struct rchan_buf *buf) |
b86ff981 JA |
209 | { |
210 | struct rchan *chan = buf->chan; | |
211 | unsigned int i; | |
212 | ||
213 | if (likely(buf->start)) { | |
214 | vunmap(buf->start); | |
215 | for (i = 0; i < buf->page_count; i++) | |
216 | __free_page(buf->page_array[i]); | |
68ab3d88 | 217 | relay_free_page_array(buf->page_array); |
b86ff981 | 218 | } |
017c59c0 | 219 | *per_cpu_ptr(chan->buf, buf->cpu) = NULL; |
b86ff981 JA |
220 | kfree(buf->padding); |
221 | kfree(buf); | |
222 | kref_put(&chan->kref, relay_destroy_channel); | |
223 | } | |
224 | ||
225 | /** | |
226 | * relay_remove_buf - remove a channel buffer | |
4c78a663 | 227 | * @kref: target kernel reference that contains the relay buffer |
b86ff981 | 228 | * |
e227867f | 229 | * Removes the file from the filesystem, which also frees the |
b86ff981 JA |
230 | * rchan_buf_struct and the channel buffer. Should only be called from |
231 | * kref_put(). | |
232 | */ | |
01c55ed3 | 233 | static void relay_remove_buf(struct kref *kref) |
b86ff981 JA |
234 | { |
235 | struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref); | |
b86ff981 JA |
236 | relay_destroy_buf(buf); |
237 | } | |
238 | ||
239 | /** | |
240 | * relay_buf_empty - boolean, is the channel buffer empty? | |
241 | * @buf: channel buffer | |
242 | * | |
243 | * Returns 1 if the buffer is empty, 0 otherwise. | |
244 | */ | |
01c55ed3 | 245 | static int relay_buf_empty(struct rchan_buf *buf) |
b86ff981 JA |
246 | { |
247 | return (buf->subbufs_produced - buf->subbufs_consumed) ? 0 : 1; | |
248 | } | |
b86ff981 JA |
249 | |
250 | /** | |
251 | * relay_buf_full - boolean, is the channel buffer full? | |
252 | * @buf: channel buffer | |
253 | * | |
254 | * Returns 1 if the buffer is full, 0 otherwise. | |
255 | */ | |
256 | int relay_buf_full(struct rchan_buf *buf) | |
257 | { | |
258 | size_t ready = buf->subbufs_produced - buf->subbufs_consumed; | |
259 | return (ready >= buf->chan->n_subbufs) ? 1 : 0; | |
260 | } | |
261 | EXPORT_SYMBOL_GPL(relay_buf_full); | |
262 | ||
263 | /* | |
264 | * High-level relay kernel API and associated functions. | |
265 | */ | |
266 | ||
267 | /* | |
268 | * rchan_callback implementations defining default channel behavior. Used | |
269 | * in place of corresponding NULL values in client callback struct. | |
270 | */ | |
271 | ||
272 | /* | |
273 | * subbuf_start() default callback. Does nothing. | |
274 | */ | |
275 | static int subbuf_start_default_callback (struct rchan_buf *buf, | |
276 | void *subbuf, | |
277 | void *prev_subbuf, | |
278 | size_t prev_padding) | |
279 | { | |
280 | if (relay_buf_full(buf)) | |
281 | return 0; | |
282 | ||
283 | return 1; | |
284 | } | |
285 | ||
286 | /* | |
287 | * buf_mapped() default callback. Does nothing. | |
288 | */ | |
289 | static void buf_mapped_default_callback(struct rchan_buf *buf, | |
290 | struct file *filp) | |
291 | { | |
292 | } | |
293 | ||
294 | /* | |
295 | * buf_unmapped() default callback. Does nothing. | |
296 | */ | |
297 | static void buf_unmapped_default_callback(struct rchan_buf *buf, | |
298 | struct file *filp) | |
299 | { | |
300 | } | |
301 | ||
302 | /* | |
303 | * create_buf_file_create() default callback. Does nothing. | |
304 | */ | |
305 | static struct dentry *create_buf_file_default_callback(const char *filename, | |
306 | struct dentry *parent, | |
f4ae40a6 | 307 | umode_t mode, |
b86ff981 JA |
308 | struct rchan_buf *buf, |
309 | int *is_global) | |
310 | { | |
311 | return NULL; | |
312 | } | |
313 | ||
314 | /* | |
315 | * remove_buf_file() default callback. Does nothing. | |
316 | */ | |
317 | static int remove_buf_file_default_callback(struct dentry *dentry) | |
318 | { | |
319 | return -EINVAL; | |
320 | } | |
321 | ||
322 | /* relay channel default callbacks */ | |
323 | static struct rchan_callbacks default_channel_callbacks = { | |
324 | .subbuf_start = subbuf_start_default_callback, | |
325 | .buf_mapped = buf_mapped_default_callback, | |
326 | .buf_unmapped = buf_unmapped_default_callback, | |
327 | .create_buf_file = create_buf_file_default_callback, | |
328 | .remove_buf_file = remove_buf_file_default_callback, | |
329 | }; | |
330 | ||
331 | /** | |
332 | * wakeup_readers - wake up readers waiting on a channel | |
26b5679e | 333 | * @work: contains the channel buffer |
b86ff981 | 334 | * |
26b5679e | 335 | * This is the function used to defer reader waking |
b86ff981 | 336 | */ |
26b5679e | 337 | static void wakeup_readers(struct irq_work *work) |
b86ff981 | 338 | { |
26b5679e PZ |
339 | struct rchan_buf *buf; |
340 | ||
341 | buf = container_of(work, struct rchan_buf, wakeup_work); | |
b86ff981 JA |
342 | wake_up_interruptible(&buf->read_wait); |
343 | } | |
344 | ||
345 | /** | |
346 | * __relay_reset - reset a channel buffer | |
347 | * @buf: the channel buffer | |
348 | * @init: 1 if this is a first-time initialization | |
349 | * | |
72fd4a35 | 350 | * See relay_reset() for description of effect. |
b86ff981 | 351 | */ |
192636ad | 352 | static void __relay_reset(struct rchan_buf *buf, unsigned int init) |
b86ff981 JA |
353 | { |
354 | size_t i; | |
355 | ||
356 | if (init) { | |
357 | init_waitqueue_head(&buf->read_wait); | |
358 | kref_init(&buf->kref); | |
26b5679e PZ |
359 | init_irq_work(&buf->wakeup_work, wakeup_readers); |
360 | } else { | |
361 | irq_work_sync(&buf->wakeup_work); | |
362 | } | |
b86ff981 JA |
363 | |
364 | buf->subbufs_produced = 0; | |
365 | buf->subbufs_consumed = 0; | |
366 | buf->bytes_consumed = 0; | |
367 | buf->finalized = 0; | |
368 | buf->data = buf->start; | |
369 | buf->offset = 0; | |
370 | ||
371 | for (i = 0; i < buf->chan->n_subbufs; i++) | |
372 | buf->padding[i] = 0; | |
373 | ||
374 | buf->chan->cb->subbuf_start(buf, buf->data, NULL, 0); | |
375 | } | |
376 | ||
377 | /** | |
378 | * relay_reset - reset the channel | |
379 | * @chan: the channel | |
380 | * | |
381 | * This has the effect of erasing all data from all channel buffers | |
382 | * and restarting the channel in its initial state. The buffers | |
383 | * are not freed, so any mappings are still in effect. | |
384 | * | |
72fd4a35 | 385 | * NOTE. Care should be taken that the channel isn't actually |
b86ff981 JA |
386 | * being used by anything when this call is made. |
387 | */ | |
388 | void relay_reset(struct rchan *chan) | |
389 | { | |
017c59c0 | 390 | struct rchan_buf *buf; |
b86ff981 | 391 | unsigned int i; |
b86ff981 JA |
392 | |
393 | if (!chan) | |
394 | return; | |
395 | ||
017c59c0 AG |
396 | if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0))) { |
397 | __relay_reset(buf, 0); | |
23c88752 | 398 | return; |
b86ff981 | 399 | } |
23c88752 MD |
400 | |
401 | mutex_lock(&relay_channels_mutex); | |
98ba4031 | 402 | for_each_possible_cpu(i) |
017c59c0 AG |
403 | if ((buf = *per_cpu_ptr(chan->buf, i))) |
404 | __relay_reset(buf, 0); | |
23c88752 | 405 | mutex_unlock(&relay_channels_mutex); |
b86ff981 JA |
406 | } |
407 | EXPORT_SYMBOL_GPL(relay_reset); | |
408 | ||
20d8b67c EGM |
409 | static inline void relay_set_buf_dentry(struct rchan_buf *buf, |
410 | struct dentry *dentry) | |
411 | { | |
412 | buf->dentry = dentry; | |
7682c918 | 413 | d_inode(buf->dentry)->i_size = buf->early_bytes; |
20d8b67c EGM |
414 | } |
415 | ||
416 | static struct dentry *relay_create_buf_file(struct rchan *chan, | |
417 | struct rchan_buf *buf, | |
418 | unsigned int cpu) | |
419 | { | |
420 | struct dentry *dentry; | |
421 | char *tmpname; | |
422 | ||
423 | tmpname = kzalloc(NAME_MAX + 1, GFP_KERNEL); | |
424 | if (!tmpname) | |
425 | return NULL; | |
426 | snprintf(tmpname, NAME_MAX, "%s%d", chan->base_filename, cpu); | |
427 | ||
428 | /* Create file in fs */ | |
429 | dentry = chan->cb->create_buf_file(tmpname, chan->parent, | |
430 | S_IRUSR, buf, | |
431 | &chan->is_global); | |
2c1cf00e GKH |
432 | if (IS_ERR(dentry)) |
433 | dentry = NULL; | |
20d8b67c EGM |
434 | |
435 | kfree(tmpname); | |
436 | ||
437 | return dentry; | |
438 | } | |
439 | ||
4c78a663 | 440 | /* |
b86ff981 JA |
441 | * relay_open_buf - create a new relay channel buffer |
442 | * | |
23c88752 | 443 | * used by relay_open() and CPU hotplug. |
b86ff981 | 444 | */ |
23c88752 | 445 | static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu) |
b86ff981 | 446 | { |
23c88752 | 447 | struct rchan_buf *buf = NULL; |
b86ff981 JA |
448 | struct dentry *dentry; |
449 | ||
23c88752 | 450 | if (chan->is_global) |
017c59c0 | 451 | return *per_cpu_ptr(chan->buf, 0); |
b86ff981 JA |
452 | |
453 | buf = relay_create_buf(chan); | |
454 | if (!buf) | |
20d8b67c EGM |
455 | return NULL; |
456 | ||
457 | if (chan->has_base_filename) { | |
458 | dentry = relay_create_buf_file(chan, buf, cpu); | |
459 | if (!dentry) | |
460 | goto free_buf; | |
461 | relay_set_buf_dentry(buf, dentry); | |
59dbb2a0 AG |
462 | } else { |
463 | /* Only retrieve global info, nothing more, nothing less */ | |
464 | dentry = chan->cb->create_buf_file(NULL, NULL, | |
465 | S_IRUSR, buf, | |
466 | &chan->is_global); | |
2c1cf00e | 467 | if (IS_ERR_OR_NULL(dentry)) |
59dbb2a0 | 468 | goto free_buf; |
20d8b67c | 469 | } |
23c88752 MD |
470 | |
471 | buf->cpu = cpu; | |
472 | __relay_reset(buf, 1); | |
b86ff981 | 473 | |
23c88752 | 474 | if(chan->is_global) { |
017c59c0 | 475 | *per_cpu_ptr(chan->buf, 0) = buf; |
23c88752 MD |
476 | buf->cpu = 0; |
477 | } | |
478 | ||
20d8b67c | 479 | return buf; |
23c88752 MD |
480 | |
481 | free_buf: | |
482 | relay_destroy_buf(buf); | |
20d8b67c | 483 | return NULL; |
b86ff981 JA |
484 | } |
485 | ||
486 | /** | |
487 | * relay_close_buf - close a channel buffer | |
488 | * @buf: channel buffer | |
489 | * | |
490 | * Marks the buffer finalized and restores the default callbacks. | |
491 | * The channel buffer and channel buffer data structure are then freed | |
492 | * automatically when the last reference is given up. | |
493 | */ | |
192636ad | 494 | static void relay_close_buf(struct rchan_buf *buf) |
b86ff981 JA |
495 | { |
496 | buf->finalized = 1; | |
26b5679e | 497 | irq_work_sync(&buf->wakeup_work); |
b8d4a5bf | 498 | buf->chan->cb->remove_buf_file(buf->dentry); |
b86ff981 JA |
499 | kref_put(&buf->kref, relay_remove_buf); |
500 | } | |
501 | ||
192636ad | 502 | static void setup_callbacks(struct rchan *chan, |
b86ff981 JA |
503 | struct rchan_callbacks *cb) |
504 | { | |
505 | if (!cb) { | |
506 | chan->cb = &default_channel_callbacks; | |
507 | return; | |
508 | } | |
509 | ||
510 | if (!cb->subbuf_start) | |
511 | cb->subbuf_start = subbuf_start_default_callback; | |
512 | if (!cb->buf_mapped) | |
513 | cb->buf_mapped = buf_mapped_default_callback; | |
514 | if (!cb->buf_unmapped) | |
515 | cb->buf_unmapped = buf_unmapped_default_callback; | |
516 | if (!cb->create_buf_file) | |
517 | cb->create_buf_file = create_buf_file_default_callback; | |
518 | if (!cb->remove_buf_file) | |
519 | cb->remove_buf_file = remove_buf_file_default_callback; | |
520 | chan->cb = cb; | |
521 | } | |
522 | ||
e6d4989a | 523 | int relay_prepare_cpu(unsigned int cpu) |
23c88752 | 524 | { |
23c88752 | 525 | struct rchan *chan; |
017c59c0 | 526 | struct rchan_buf *buf; |
23c88752 | 527 | |
e6d4989a RW |
528 | mutex_lock(&relay_channels_mutex); |
529 | list_for_each_entry(chan, &relay_channels, list) { | |
530 | if ((buf = *per_cpu_ptr(chan->buf, cpu))) | |
531 | continue; | |
532 | buf = relay_open_buf(chan, cpu); | |
533 | if (!buf) { | |
534 | pr_err("relay: cpu %d buffer creation failed\n", cpu); | |
535 | mutex_unlock(&relay_channels_mutex); | |
536 | return -ENOMEM; | |
23c88752 | 537 | } |
e6d4989a | 538 | *per_cpu_ptr(chan->buf, cpu) = buf; |
23c88752 | 539 | } |
e6d4989a RW |
540 | mutex_unlock(&relay_channels_mutex); |
541 | return 0; | |
23c88752 MD |
542 | } |
543 | ||
b86ff981 JA |
544 | /** |
545 | * relay_open - create a new relay channel | |
20d8b67c EGM |
546 | * @base_filename: base name of files to create, %NULL for buffering only |
547 | * @parent: dentry of parent directory, %NULL for root directory or buffer | |
b86ff981 JA |
548 | * @subbuf_size: size of sub-buffers |
549 | * @n_subbufs: number of sub-buffers | |
550 | * @cb: client callback functions | |
23c88752 | 551 | * @private_data: user-defined data |
b86ff981 | 552 | * |
4c78a663 | 553 | * Returns channel pointer if successful, %NULL otherwise. |
b86ff981 JA |
554 | * |
555 | * Creates a channel buffer for each cpu using the sizes and | |
556 | * attributes specified. The created channel buffer files | |
557 | * will be named base_filename0...base_filenameN-1. File | |
72fd4a35 | 558 | * permissions will be %S_IRUSR. |
59dbb2a0 AG |
559 | * |
560 | * If opening a buffer (@parent = NULL) that you later wish to register | |
561 | * in a filesystem, call relay_late_setup_files() once the @parent dentry | |
562 | * is available. | |
b86ff981 JA |
563 | */ |
564 | struct rchan *relay_open(const char *base_filename, | |
565 | struct dentry *parent, | |
566 | size_t subbuf_size, | |
567 | size_t n_subbufs, | |
23c88752 MD |
568 | struct rchan_callbacks *cb, |
569 | void *private_data) | |
b86ff981 JA |
570 | { |
571 | unsigned int i; | |
572 | struct rchan *chan; | |
017c59c0 | 573 | struct rchan_buf *buf; |
b86ff981 JA |
574 | |
575 | if (!(subbuf_size && n_subbufs)) | |
576 | return NULL; | |
f6302f1b DC |
577 | if (subbuf_size > UINT_MAX / n_subbufs) |
578 | return NULL; | |
b86ff981 | 579 | |
cd861280 | 580 | chan = kzalloc(sizeof(struct rchan), GFP_KERNEL); |
b86ff981 JA |
581 | if (!chan) |
582 | return NULL; | |
583 | ||
017c59c0 | 584 | chan->buf = alloc_percpu(struct rchan_buf *); |
54e200ab DA |
585 | if (!chan->buf) { |
586 | kfree(chan); | |
587 | return NULL; | |
588 | } | |
589 | ||
b86ff981 JA |
590 | chan->version = RELAYFS_CHANNEL_VERSION; |
591 | chan->n_subbufs = n_subbufs; | |
592 | chan->subbuf_size = subbuf_size; | |
a05342cb | 593 | chan->alloc_size = PAGE_ALIGN(subbuf_size * n_subbufs); |
23c88752 MD |
594 | chan->parent = parent; |
595 | chan->private_data = private_data; | |
20d8b67c EGM |
596 | if (base_filename) { |
597 | chan->has_base_filename = 1; | |
598 | strlcpy(chan->base_filename, base_filename, NAME_MAX); | |
599 | } | |
b86ff981 JA |
600 | setup_callbacks(chan, cb); |
601 | kref_init(&chan->kref); | |
602 | ||
23c88752 | 603 | mutex_lock(&relay_channels_mutex); |
b86ff981 | 604 | for_each_online_cpu(i) { |
017c59c0 AG |
605 | buf = relay_open_buf(chan, i); |
606 | if (!buf) | |
b86ff981 | 607 | goto free_bufs; |
017c59c0 | 608 | *per_cpu_ptr(chan->buf, i) = buf; |
b86ff981 | 609 | } |
23c88752 MD |
610 | list_add(&chan->list, &relay_channels); |
611 | mutex_unlock(&relay_channels_mutex); | |
b86ff981 | 612 | |
b86ff981 JA |
613 | return chan; |
614 | ||
615 | free_bufs: | |
98ba4031 | 616 | for_each_possible_cpu(i) { |
017c59c0 AG |
617 | if ((buf = *per_cpu_ptr(chan->buf, i))) |
618 | relay_close_buf(buf); | |
b86ff981 | 619 | } |
b86ff981 | 620 | |
b86ff981 | 621 | kref_put(&chan->kref, relay_destroy_channel); |
23c88752 | 622 | mutex_unlock(&relay_channels_mutex); |
b86ff981 JA |
623 | return NULL; |
624 | } | |
625 | EXPORT_SYMBOL_GPL(relay_open); | |
626 | ||
20d8b67c EGM |
627 | struct rchan_percpu_buf_dispatcher { |
628 | struct rchan_buf *buf; | |
629 | struct dentry *dentry; | |
630 | }; | |
631 | ||
632 | /* Called in atomic context. */ | |
633 | static void __relay_set_buf_dentry(void *info) | |
634 | { | |
635 | struct rchan_percpu_buf_dispatcher *p = info; | |
636 | ||
637 | relay_set_buf_dentry(p->buf, p->dentry); | |
638 | } | |
639 | ||
640 | /** | |
641 | * relay_late_setup_files - triggers file creation | |
642 | * @chan: channel to operate on | |
643 | * @base_filename: base name of files to create | |
644 | * @parent: dentry of parent directory, %NULL for root directory | |
645 | * | |
646 | * Returns 0 if successful, non-zero otherwise. | |
647 | * | |
59dbb2a0 AG |
648 | * Use to setup files for a previously buffer-only channel created |
649 | * by relay_open() with a NULL parent dentry. | |
650 | * | |
651 | * For example, this is useful for perfomring early tracing in kernel, | |
652 | * before VFS is up and then exposing the early results once the dentry | |
653 | * is available. | |
20d8b67c EGM |
654 | */ |
655 | int relay_late_setup_files(struct rchan *chan, | |
656 | const char *base_filename, | |
657 | struct dentry *parent) | |
658 | { | |
659 | int err = 0; | |
660 | unsigned int i, curr_cpu; | |
661 | unsigned long flags; | |
662 | struct dentry *dentry; | |
017c59c0 | 663 | struct rchan_buf *buf; |
20d8b67c EGM |
664 | struct rchan_percpu_buf_dispatcher disp; |
665 | ||
666 | if (!chan || !base_filename) | |
667 | return -EINVAL; | |
668 | ||
669 | strlcpy(chan->base_filename, base_filename, NAME_MAX); | |
670 | ||
671 | mutex_lock(&relay_channels_mutex); | |
672 | /* Is chan already set up? */ | |
b786c6a9 JS |
673 | if (unlikely(chan->has_base_filename)) { |
674 | mutex_unlock(&relay_channels_mutex); | |
20d8b67c | 675 | return -EEXIST; |
b786c6a9 | 676 | } |
20d8b67c EGM |
677 | chan->has_base_filename = 1; |
678 | chan->parent = parent; | |
59dbb2a0 AG |
679 | |
680 | if (chan->is_global) { | |
681 | err = -EINVAL; | |
017c59c0 AG |
682 | buf = *per_cpu_ptr(chan->buf, 0); |
683 | if (!WARN_ON_ONCE(!buf)) { | |
684 | dentry = relay_create_buf_file(chan, buf, 0); | |
59dbb2a0 | 685 | if (dentry && !WARN_ON_ONCE(!chan->is_global)) { |
017c59c0 | 686 | relay_set_buf_dentry(buf, dentry); |
59dbb2a0 AG |
687 | err = 0; |
688 | } | |
689 | } | |
690 | mutex_unlock(&relay_channels_mutex); | |
691 | return err; | |
692 | } | |
693 | ||
20d8b67c EGM |
694 | curr_cpu = get_cpu(); |
695 | /* | |
696 | * The CPU hotplug notifier ran before us and created buffers with | |
697 | * no files associated. So it's safe to call relay_setup_buf_file() | |
698 | * on all currently online CPUs. | |
699 | */ | |
700 | for_each_online_cpu(i) { | |
017c59c0 AG |
701 | buf = *per_cpu_ptr(chan->buf, i); |
702 | if (unlikely(!buf)) { | |
7a51cffb | 703 | WARN_ONCE(1, KERN_ERR "CPU has no buffer!\n"); |
20d8b67c EGM |
704 | err = -EINVAL; |
705 | break; | |
706 | } | |
707 | ||
017c59c0 | 708 | dentry = relay_create_buf_file(chan, buf, i); |
20d8b67c EGM |
709 | if (unlikely(!dentry)) { |
710 | err = -EINVAL; | |
711 | break; | |
712 | } | |
713 | ||
714 | if (curr_cpu == i) { | |
715 | local_irq_save(flags); | |
017c59c0 | 716 | relay_set_buf_dentry(buf, dentry); |
20d8b67c EGM |
717 | local_irq_restore(flags); |
718 | } else { | |
017c59c0 | 719 | disp.buf = buf; |
20d8b67c EGM |
720 | disp.dentry = dentry; |
721 | smp_mb(); | |
722 | /* relay_channels_mutex must be held, so wait. */ | |
723 | err = smp_call_function_single(i, | |
724 | __relay_set_buf_dentry, | |
725 | &disp, 1); | |
726 | } | |
727 | if (unlikely(err)) | |
728 | break; | |
729 | } | |
730 | put_cpu(); | |
731 | mutex_unlock(&relay_channels_mutex); | |
732 | ||
733 | return err; | |
734 | } | |
59dbb2a0 | 735 | EXPORT_SYMBOL_GPL(relay_late_setup_files); |
20d8b67c | 736 | |
b86ff981 JA |
737 | /** |
738 | * relay_switch_subbuf - switch to a new sub-buffer | |
739 | * @buf: channel buffer | |
740 | * @length: size of current event | |
741 | * | |
742 | * Returns either the length passed in or 0 if full. | |
743 | * | |
744 | * Performs sub-buffer-switch tasks such as invoking callbacks, | |
745 | * updating padding counts, waking up readers, etc. | |
746 | */ | |
747 | size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length) | |
748 | { | |
749 | void *old, *new; | |
750 | size_t old_subbuf, new_subbuf; | |
751 | ||
752 | if (unlikely(length > buf->chan->subbuf_size)) | |
753 | goto toobig; | |
754 | ||
755 | if (buf->offset != buf->chan->subbuf_size + 1) { | |
756 | buf->prev_padding = buf->chan->subbuf_size - buf->offset; | |
757 | old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; | |
758 | buf->padding[old_subbuf] = buf->prev_padding; | |
759 | buf->subbufs_produced++; | |
20d8b67c | 760 | if (buf->dentry) |
7682c918 | 761 | d_inode(buf->dentry)->i_size += |
20d8b67c EGM |
762 | buf->chan->subbuf_size - |
763 | buf->padding[old_subbuf]; | |
764 | else | |
765 | buf->early_bytes += buf->chan->subbuf_size - | |
766 | buf->padding[old_subbuf]; | |
221415d7 | 767 | smp_mb(); |
26b5679e | 768 | if (waitqueue_active(&buf->read_wait)) { |
7c9cb383 TZ |
769 | /* |
770 | * Calling wake_up_interruptible() from here | |
771 | * will deadlock if we happen to be logging | |
772 | * from the scheduler (trying to re-grab | |
773 | * rq->lock), so defer it. | |
774 | */ | |
26b5679e PZ |
775 | irq_work_queue(&buf->wakeup_work); |
776 | } | |
b86ff981 JA |
777 | } |
778 | ||
779 | old = buf->data; | |
780 | new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; | |
781 | new = buf->start + new_subbuf * buf->chan->subbuf_size; | |
782 | buf->offset = 0; | |
783 | if (!buf->chan->cb->subbuf_start(buf, new, old, buf->prev_padding)) { | |
784 | buf->offset = buf->chan->subbuf_size + 1; | |
785 | return 0; | |
786 | } | |
787 | buf->data = new; | |
788 | buf->padding[new_subbuf] = 0; | |
789 | ||
790 | if (unlikely(length + buf->offset > buf->chan->subbuf_size)) | |
791 | goto toobig; | |
792 | ||
793 | return length; | |
794 | ||
795 | toobig: | |
796 | buf->chan->last_toobig = length; | |
797 | return 0; | |
798 | } | |
799 | EXPORT_SYMBOL_GPL(relay_switch_subbuf); | |
800 | ||
801 | /** | |
802 | * relay_subbufs_consumed - update the buffer's sub-buffers-consumed count | |
803 | * @chan: the channel | |
804 | * @cpu: the cpu associated with the channel buffer to update | |
805 | * @subbufs_consumed: number of sub-buffers to add to current buf's count | |
806 | * | |
807 | * Adds to the channel buffer's consumed sub-buffer count. | |
808 | * subbufs_consumed should be the number of sub-buffers newly consumed, | |
809 | * not the total consumed. | |
810 | * | |
72fd4a35 | 811 | * NOTE. Kernel clients don't need to call this function if the channel |
b86ff981 JA |
812 | * mode is 'overwrite'. |
813 | */ | |
814 | void relay_subbufs_consumed(struct rchan *chan, | |
815 | unsigned int cpu, | |
816 | size_t subbufs_consumed) | |
817 | { | |
818 | struct rchan_buf *buf; | |
819 | ||
9a29d0fb | 820 | if (!chan || cpu >= NR_CPUS) |
b86ff981 JA |
821 | return; |
822 | ||
017c59c0 | 823 | buf = *per_cpu_ptr(chan->buf, cpu); |
9a29d0fb | 824 | if (!buf || subbufs_consumed > chan->n_subbufs) |
b86ff981 JA |
825 | return; |
826 | ||
2c53d910 | 827 | if (subbufs_consumed > buf->subbufs_produced - buf->subbufs_consumed) |
b86ff981 | 828 | buf->subbufs_consumed = buf->subbufs_produced; |
2c53d910 AS |
829 | else |
830 | buf->subbufs_consumed += subbufs_consumed; | |
b86ff981 JA |
831 | } |
832 | EXPORT_SYMBOL_GPL(relay_subbufs_consumed); | |
833 | ||
834 | /** | |
835 | * relay_close - close the channel | |
836 | * @chan: the channel | |
837 | * | |
838 | * Closes all channel buffers and frees the channel. | |
839 | */ | |
840 | void relay_close(struct rchan *chan) | |
841 | { | |
017c59c0 | 842 | struct rchan_buf *buf; |
b86ff981 | 843 | unsigned int i; |
b86ff981 JA |
844 | |
845 | if (!chan) | |
846 | return; | |
847 | ||
23c88752 | 848 | mutex_lock(&relay_channels_mutex); |
017c59c0 AG |
849 | if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0))) |
850 | relay_close_buf(buf); | |
23c88752 MD |
851 | else |
852 | for_each_possible_cpu(i) | |
017c59c0 AG |
853 | if ((buf = *per_cpu_ptr(chan->buf, i))) |
854 | relay_close_buf(buf); | |
b86ff981 JA |
855 | |
856 | if (chan->last_toobig) | |
857 | printk(KERN_WARNING "relay: one or more items not logged " | |
5b5e0928 | 858 | "[item size (%zd) > sub-buffer size (%zd)]\n", |
b86ff981 JA |
859 | chan->last_toobig, chan->subbuf_size); |
860 | ||
23c88752 | 861 | list_del(&chan->list); |
b86ff981 | 862 | kref_put(&chan->kref, relay_destroy_channel); |
23c88752 | 863 | mutex_unlock(&relay_channels_mutex); |
b86ff981 JA |
864 | } |
865 | EXPORT_SYMBOL_GPL(relay_close); | |
866 | ||
867 | /** | |
868 | * relay_flush - close the channel | |
869 | * @chan: the channel | |
870 | * | |
4c78a663 | 871 | * Flushes all channel buffers, i.e. forces buffer switch. |
b86ff981 JA |
872 | */ |
873 | void relay_flush(struct rchan *chan) | |
874 | { | |
017c59c0 | 875 | struct rchan_buf *buf; |
b86ff981 | 876 | unsigned int i; |
b86ff981 JA |
877 | |
878 | if (!chan) | |
879 | return; | |
880 | ||
017c59c0 AG |
881 | if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0))) { |
882 | relay_switch_subbuf(buf, 0); | |
23c88752 | 883 | return; |
b86ff981 | 884 | } |
23c88752 MD |
885 | |
886 | mutex_lock(&relay_channels_mutex); | |
887 | for_each_possible_cpu(i) | |
017c59c0 AG |
888 | if ((buf = *per_cpu_ptr(chan->buf, i))) |
889 | relay_switch_subbuf(buf, 0); | |
23c88752 | 890 | mutex_unlock(&relay_channels_mutex); |
b86ff981 JA |
891 | } |
892 | EXPORT_SYMBOL_GPL(relay_flush); | |
893 | ||
894 | /** | |
895 | * relay_file_open - open file op for relay files | |
896 | * @inode: the inode | |
897 | * @filp: the file | |
898 | * | |
899 | * Increments the channel buffer refcount. | |
900 | */ | |
901 | static int relay_file_open(struct inode *inode, struct file *filp) | |
902 | { | |
8e18e294 | 903 | struct rchan_buf *buf = inode->i_private; |
b86ff981 JA |
904 | kref_get(&buf->kref); |
905 | filp->private_data = buf; | |
906 | ||
37529fe9 | 907 | return nonseekable_open(inode, filp); |
b86ff981 JA |
908 | } |
909 | ||
910 | /** | |
911 | * relay_file_mmap - mmap file op for relay files | |
912 | * @filp: the file | |
913 | * @vma: the vma describing what to map | |
914 | * | |
72fd4a35 | 915 | * Calls upon relay_mmap_buf() to map the file into user space. |
b86ff981 JA |
916 | */ |
917 | static int relay_file_mmap(struct file *filp, struct vm_area_struct *vma) | |
918 | { | |
919 | struct rchan_buf *buf = filp->private_data; | |
920 | return relay_mmap_buf(buf, vma); | |
921 | } | |
922 | ||
923 | /** | |
924 | * relay_file_poll - poll file op for relay files | |
925 | * @filp: the file | |
926 | * @wait: poll table | |
927 | * | |
928 | * Poll implemention. | |
929 | */ | |
9dd95748 | 930 | static __poll_t relay_file_poll(struct file *filp, poll_table *wait) |
b86ff981 | 931 | { |
9dd95748 | 932 | __poll_t mask = 0; |
b86ff981 JA |
933 | struct rchan_buf *buf = filp->private_data; |
934 | ||
935 | if (buf->finalized) | |
a9a08845 | 936 | return EPOLLERR; |
b86ff981 JA |
937 | |
938 | if (filp->f_mode & FMODE_READ) { | |
939 | poll_wait(filp, &buf->read_wait, wait); | |
940 | if (!relay_buf_empty(buf)) | |
a9a08845 | 941 | mask |= EPOLLIN | EPOLLRDNORM; |
b86ff981 JA |
942 | } |
943 | ||
944 | return mask; | |
945 | } | |
946 | ||
947 | /** | |
948 | * relay_file_release - release file op for relay files | |
949 | * @inode: the inode | |
950 | * @filp: the file | |
951 | * | |
952 | * Decrements the channel refcount, as the filesystem is | |
953 | * no longer using it. | |
954 | */ | |
955 | static int relay_file_release(struct inode *inode, struct file *filp) | |
956 | { | |
957 | struct rchan_buf *buf = filp->private_data; | |
958 | kref_put(&buf->kref, relay_remove_buf); | |
959 | ||
960 | return 0; | |
961 | } | |
962 | ||
4c78a663 | 963 | /* |
b86ff981 JA |
964 | * relay_file_read_consume - update the consumed count for the buffer |
965 | */ | |
966 | static void relay_file_read_consume(struct rchan_buf *buf, | |
967 | size_t read_pos, | |
968 | size_t bytes_consumed) | |
969 | { | |
970 | size_t subbuf_size = buf->chan->subbuf_size; | |
971 | size_t n_subbufs = buf->chan->n_subbufs; | |
972 | size_t read_subbuf; | |
973 | ||
32194450 TZ |
974 | if (buf->subbufs_produced == buf->subbufs_consumed && |
975 | buf->offset == buf->bytes_consumed) | |
976 | return; | |
977 | ||
b86ff981 JA |
978 | if (buf->bytes_consumed + bytes_consumed > subbuf_size) { |
979 | relay_subbufs_consumed(buf->chan, buf->cpu, 1); | |
980 | buf->bytes_consumed = 0; | |
981 | } | |
982 | ||
983 | buf->bytes_consumed += bytes_consumed; | |
a66e356c MH |
984 | if (!read_pos) |
985 | read_subbuf = buf->subbufs_consumed % n_subbufs; | |
986 | else | |
987 | read_subbuf = read_pos / buf->chan->subbuf_size; | |
b86ff981 JA |
988 | if (buf->bytes_consumed + buf->padding[read_subbuf] == subbuf_size) { |
989 | if ((read_subbuf == buf->subbufs_produced % n_subbufs) && | |
990 | (buf->offset == subbuf_size)) | |
991 | return; | |
992 | relay_subbufs_consumed(buf->chan, buf->cpu, 1); | |
993 | buf->bytes_consumed = 0; | |
994 | } | |
995 | } | |
996 | ||
4c78a663 | 997 | /* |
b86ff981 JA |
998 | * relay_file_read_avail - boolean, are there unconsumed bytes available? |
999 | */ | |
341a7213 | 1000 | static int relay_file_read_avail(struct rchan_buf *buf) |
b86ff981 | 1001 | { |
b86ff981 JA |
1002 | size_t subbuf_size = buf->chan->subbuf_size; |
1003 | size_t n_subbufs = buf->chan->n_subbufs; | |
221415d7 JA |
1004 | size_t produced = buf->subbufs_produced; |
1005 | size_t consumed = buf->subbufs_consumed; | |
b86ff981 | 1006 | |
341a7213 | 1007 | relay_file_read_consume(buf, 0, 0); |
b86ff981 | 1008 | |
32194450 TZ |
1009 | consumed = buf->subbufs_consumed; |
1010 | ||
221415d7 JA |
1011 | if (unlikely(buf->offset > subbuf_size)) { |
1012 | if (produced == consumed) | |
1013 | return 0; | |
1014 | return 1; | |
b86ff981 JA |
1015 | } |
1016 | ||
221415d7 | 1017 | if (unlikely(produced - consumed >= n_subbufs)) { |
a66e356c | 1018 | consumed = produced - n_subbufs + 1; |
221415d7 | 1019 | buf->subbufs_consumed = consumed; |
a66e356c | 1020 | buf->bytes_consumed = 0; |
221415d7 | 1021 | } |
1bfbc608 | 1022 | |
221415d7 JA |
1023 | produced = (produced % n_subbufs) * subbuf_size + buf->offset; |
1024 | consumed = (consumed % n_subbufs) * subbuf_size + buf->bytes_consumed; | |
1025 | ||
1026 | if (consumed > produced) | |
1027 | produced += n_subbufs * subbuf_size; | |
1bfbc608 | 1028 | |
32194450 TZ |
1029 | if (consumed == produced) { |
1030 | if (buf->offset == subbuf_size && | |
1031 | buf->subbufs_produced > buf->subbufs_consumed) | |
1032 | return 1; | |
b86ff981 | 1033 | return 0; |
32194450 | 1034 | } |
b86ff981 | 1035 | |
b86ff981 JA |
1036 | return 1; |
1037 | } | |
1038 | ||
1039 | /** | |
1040 | * relay_file_read_subbuf_avail - return bytes available in sub-buffer | |
4c78a663 RD |
1041 | * @read_pos: file read position |
1042 | * @buf: relay channel buffer | |
b86ff981 JA |
1043 | */ |
1044 | static size_t relay_file_read_subbuf_avail(size_t read_pos, | |
1045 | struct rchan_buf *buf) | |
1046 | { | |
1047 | size_t padding, avail = 0; | |
1048 | size_t read_subbuf, read_offset, write_subbuf, write_offset; | |
1049 | size_t subbuf_size = buf->chan->subbuf_size; | |
1050 | ||
1051 | write_subbuf = (buf->data - buf->start) / subbuf_size; | |
1052 | write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset; | |
1053 | read_subbuf = read_pos / subbuf_size; | |
1054 | read_offset = read_pos % subbuf_size; | |
1055 | padding = buf->padding[read_subbuf]; | |
1056 | ||
1057 | if (read_subbuf == write_subbuf) { | |
1058 | if (read_offset + padding < write_offset) | |
1059 | avail = write_offset - (read_offset + padding); | |
1060 | } else | |
1061 | avail = (subbuf_size - padding) - read_offset; | |
1062 | ||
1063 | return avail; | |
1064 | } | |
1065 | ||
1066 | /** | |
1067 | * relay_file_read_start_pos - find the first available byte to read | |
4c78a663 | 1068 | * @buf: relay channel buffer |
b86ff981 | 1069 | * |
341a7213 | 1070 | * If the read_pos is in the middle of padding, return the |
b86ff981 JA |
1071 | * position of the first actually available byte, otherwise |
1072 | * return the original value. | |
1073 | */ | |
341a7213 | 1074 | static size_t relay_file_read_start_pos(struct rchan_buf *buf) |
b86ff981 JA |
1075 | { |
1076 | size_t read_subbuf, padding, padding_start, padding_end; | |
1077 | size_t subbuf_size = buf->chan->subbuf_size; | |
1078 | size_t n_subbufs = buf->chan->n_subbufs; | |
8d62fdeb | 1079 | size_t consumed = buf->subbufs_consumed % n_subbufs; |
341a7213 | 1080 | size_t read_pos = consumed * subbuf_size + buf->bytes_consumed; |
b86ff981 JA |
1081 | |
1082 | read_subbuf = read_pos / subbuf_size; | |
1083 | padding = buf->padding[read_subbuf]; | |
1084 | padding_start = (read_subbuf + 1) * subbuf_size - padding; | |
1085 | padding_end = (read_subbuf + 1) * subbuf_size; | |
1086 | if (read_pos >= padding_start && read_pos < padding_end) { | |
1087 | read_subbuf = (read_subbuf + 1) % n_subbufs; | |
1088 | read_pos = read_subbuf * subbuf_size; | |
1089 | } | |
1090 | ||
1091 | return read_pos; | |
1092 | } | |
1093 | ||
1094 | /** | |
1095 | * relay_file_read_end_pos - return the new read position | |
4c78a663 RD |
1096 | * @read_pos: file read position |
1097 | * @buf: relay channel buffer | |
1098 | * @count: number of bytes to be read | |
b86ff981 JA |
1099 | */ |
1100 | static size_t relay_file_read_end_pos(struct rchan_buf *buf, | |
1101 | size_t read_pos, | |
1102 | size_t count) | |
1103 | { | |
1104 | size_t read_subbuf, padding, end_pos; | |
1105 | size_t subbuf_size = buf->chan->subbuf_size; | |
1106 | size_t n_subbufs = buf->chan->n_subbufs; | |
1107 | ||
1108 | read_subbuf = read_pos / subbuf_size; | |
1109 | padding = buf->padding[read_subbuf]; | |
1110 | if (read_pos % subbuf_size + count + padding == subbuf_size) | |
1111 | end_pos = (read_subbuf + 1) * subbuf_size; | |
1112 | else | |
1113 | end_pos = read_pos + count; | |
1114 | if (end_pos >= subbuf_size * n_subbufs) | |
1115 | end_pos = 0; | |
1116 | ||
1117 | return end_pos; | |
1118 | } | |
1119 | ||
a7c22421 AV |
1120 | static ssize_t relay_file_read(struct file *filp, |
1121 | char __user *buffer, | |
1122 | size_t count, | |
1123 | loff_t *ppos) | |
221415d7 | 1124 | { |
6dac40a7 TZ |
1125 | struct rchan_buf *buf = filp->private_data; |
1126 | size_t read_start, avail; | |
a7c22421 | 1127 | size_t written = 0; |
6dac40a7 | 1128 | int ret; |
221415d7 | 1129 | |
a7c22421 | 1130 | if (!count) |
221415d7 JA |
1131 | return 0; |
1132 | ||
5955102c | 1133 | inode_lock(file_inode(filp)); |
221415d7 | 1134 | do { |
a7c22421 AV |
1135 | void *from; |
1136 | ||
341a7213 | 1137 | if (!relay_file_read_avail(buf)) |
6dac40a7 TZ |
1138 | break; |
1139 | ||
341a7213 | 1140 | read_start = relay_file_read_start_pos(buf); |
6dac40a7 TZ |
1141 | avail = relay_file_read_subbuf_avail(read_start, buf); |
1142 | if (!avail) | |
221415d7 | 1143 | break; |
221415d7 | 1144 | |
a7c22421 AV |
1145 | avail = min(count, avail); |
1146 | from = buf->start + read_start; | |
1147 | ret = avail; | |
1148 | if (copy_to_user(buffer, from, avail)) | |
6dac40a7 TZ |
1149 | break; |
1150 | ||
a7c22421 AV |
1151 | buffer += ret; |
1152 | written += ret; | |
1153 | count -= ret; | |
6dac40a7 | 1154 | |
a7c22421 AV |
1155 | relay_file_read_consume(buf, read_start, ret); |
1156 | *ppos = relay_file_read_end_pos(buf, read_start, ret); | |
1157 | } while (count); | |
1158 | inode_unlock(file_inode(filp)); | |
6dac40a7 | 1159 | |
a7c22421 | 1160 | return written; |
6dac40a7 TZ |
1161 | } |
1162 | ||
1db60cf2 JA |
1163 | static void relay_consume_bytes(struct rchan_buf *rbuf, int bytes_consumed) |
1164 | { | |
1165 | rbuf->bytes_consumed += bytes_consumed; | |
1166 | ||
1167 | if (rbuf->bytes_consumed >= rbuf->chan->subbuf_size) { | |
1168 | relay_subbufs_consumed(rbuf->chan, rbuf->cpu, 1); | |
1169 | rbuf->bytes_consumed %= rbuf->chan->subbuf_size; | |
1170 | } | |
1171 | } | |
1172 | ||
ebf99093 TZ |
1173 | static void relay_pipe_buf_release(struct pipe_inode_info *pipe, |
1174 | struct pipe_buffer *buf) | |
6dac40a7 | 1175 | { |
ebf99093 TZ |
1176 | struct rchan_buf *rbuf; |
1177 | ||
1178 | rbuf = (struct rchan_buf *)page_private(buf->page); | |
1db60cf2 | 1179 | relay_consume_bytes(rbuf, buf->private); |
ebf99093 TZ |
1180 | } |
1181 | ||
28dfef8f | 1182 | static const struct pipe_buf_operations relay_pipe_buf_ops = { |
c928f642 CH |
1183 | .release = relay_pipe_buf_release, |
1184 | .try_steal = generic_pipe_buf_try_steal, | |
1185 | .get = generic_pipe_buf_get, | |
ebf99093 TZ |
1186 | }; |
1187 | ||
5eb7f9fa JA |
1188 | static void relay_page_release(struct splice_pipe_desc *spd, unsigned int i) |
1189 | { | |
1190 | } | |
1191 | ||
d3f35d98 | 1192 | /* |
ebf99093 TZ |
1193 | * subbuf_splice_actor - splice up to one subbuf's worth of data |
1194 | */ | |
5f1664f9 | 1195 | static ssize_t subbuf_splice_actor(struct file *in, |
ebf99093 TZ |
1196 | loff_t *ppos, |
1197 | struct pipe_inode_info *pipe, | |
1198 | size_t len, | |
1199 | unsigned int flags, | |
1200 | int *nonpad_ret) | |
1201 | { | |
5f1664f9 | 1202 | unsigned int pidx, poff, total_len, subbuf_pages, nr_pages; |
ebf99093 TZ |
1203 | struct rchan_buf *rbuf = in->private_data; |
1204 | unsigned int subbuf_size = rbuf->chan->subbuf_size; | |
24da24de TZ |
1205 | uint64_t pos = (uint64_t) *ppos; |
1206 | uint32_t alloc_size = (uint32_t) rbuf->chan->alloc_size; | |
1207 | size_t read_start = (size_t) do_div(pos, alloc_size); | |
ebf99093 TZ |
1208 | size_t read_subbuf = read_start / subbuf_size; |
1209 | size_t padding = rbuf->padding[read_subbuf]; | |
1210 | size_t nonpad_end = read_subbuf * subbuf_size + subbuf_size - padding; | |
35f3d14d JA |
1211 | struct page *pages[PIPE_DEF_BUFFERS]; |
1212 | struct partial_page partial[PIPE_DEF_BUFFERS]; | |
1db60cf2 JA |
1213 | struct splice_pipe_desc spd = { |
1214 | .pages = pages, | |
1215 | .nr_pages = 0, | |
047fe360 | 1216 | .nr_pages_max = PIPE_DEF_BUFFERS, |
1db60cf2 | 1217 | .partial = partial, |
1db60cf2 | 1218 | .ops = &relay_pipe_buf_ops, |
5eb7f9fa | 1219 | .spd_release = relay_page_release, |
1db60cf2 | 1220 | }; |
5f1664f9 | 1221 | ssize_t ret; |
ebf99093 TZ |
1222 | |
1223 | if (rbuf->subbufs_produced == rbuf->subbufs_consumed) | |
1224 | return 0; | |
35f3d14d JA |
1225 | if (splice_grow_spd(pipe, &spd)) |
1226 | return -ENOMEM; | |
ebf99093 | 1227 | |
1db60cf2 JA |
1228 | /* |
1229 | * Adjust read len, if longer than what is available | |
1230 | */ | |
1231 | if (len > (subbuf_size - read_start % subbuf_size)) | |
1232 | len = subbuf_size - read_start % subbuf_size; | |
ebf99093 TZ |
1233 | |
1234 | subbuf_pages = rbuf->chan->alloc_size >> PAGE_SHIFT; | |
1235 | pidx = (read_start / PAGE_SIZE) % subbuf_pages; | |
1236 | poff = read_start & ~PAGE_MASK; | |
a786c06d | 1237 | nr_pages = min_t(unsigned int, subbuf_pages, spd.nr_pages_max); |
ebf99093 | 1238 | |
16d54669 | 1239 | for (total_len = 0; spd.nr_pages < nr_pages; spd.nr_pages++) { |
1db60cf2 JA |
1240 | unsigned int this_len, this_end, private; |
1241 | unsigned int cur_pos = read_start + total_len; | |
ebf99093 | 1242 | |
1db60cf2 | 1243 | if (!len) |
ebf99093 | 1244 | break; |
ebf99093 | 1245 | |
1db60cf2 JA |
1246 | this_len = min_t(unsigned long, len, PAGE_SIZE - poff); |
1247 | private = this_len; | |
ebf99093 | 1248 | |
1db60cf2 JA |
1249 | spd.pages[spd.nr_pages] = rbuf->page_array[pidx]; |
1250 | spd.partial[spd.nr_pages].offset = poff; | |
ebf99093 | 1251 | |
1db60cf2 JA |
1252 | this_end = cur_pos + this_len; |
1253 | if (this_end >= nonpad_end) { | |
1254 | this_len = nonpad_end - cur_pos; | |
1255 | private = this_len + padding; | |
ebf99093 | 1256 | } |
1db60cf2 JA |
1257 | spd.partial[spd.nr_pages].len = this_len; |
1258 | spd.partial[spd.nr_pages].private = private; | |
ebf99093 | 1259 | |
1db60cf2 JA |
1260 | len -= this_len; |
1261 | total_len += this_len; | |
1262 | poff = 0; | |
1263 | pidx = (pidx + 1) % subbuf_pages; | |
ebf99093 | 1264 | |
1db60cf2 JA |
1265 | if (this_end >= nonpad_end) { |
1266 | spd.nr_pages++; | |
ebf99093 TZ |
1267 | break; |
1268 | } | |
ebf99093 TZ |
1269 | } |
1270 | ||
35f3d14d | 1271 | ret = 0; |
1db60cf2 | 1272 | if (!spd.nr_pages) |
35f3d14d | 1273 | goto out; |
ebf99093 | 1274 | |
1db60cf2 JA |
1275 | ret = *nonpad_ret = splice_to_pipe(pipe, &spd); |
1276 | if (ret < 0 || ret < total_len) | |
35f3d14d | 1277 | goto out; |
ebf99093 | 1278 | |
1db60cf2 JA |
1279 | if (read_start + ret == nonpad_end) |
1280 | ret += padding; | |
1281 | ||
35f3d14d | 1282 | out: |
047fe360 ED |
1283 | splice_shrink_spd(&spd); |
1284 | return ret; | |
ebf99093 TZ |
1285 | } |
1286 | ||
1287 | static ssize_t relay_file_splice_read(struct file *in, | |
1288 | loff_t *ppos, | |
1289 | struct pipe_inode_info *pipe, | |
1290 | size_t len, | |
1291 | unsigned int flags) | |
1292 | { | |
1293 | ssize_t spliced; | |
1294 | int ret; | |
1295 | int nonpad_ret = 0; | |
1296 | ||
1297 | ret = 0; | |
1298 | spliced = 0; | |
1299 | ||
a82c53a0 | 1300 | while (len && !spliced) { |
ebf99093 TZ |
1301 | ret = subbuf_splice_actor(in, ppos, pipe, len, flags, &nonpad_ret); |
1302 | if (ret < 0) | |
1303 | break; | |
1304 | else if (!ret) { | |
fbb5b7ae | 1305 | if (flags & SPLICE_F_NONBLOCK) |
ebf99093 | 1306 | ret = -EAGAIN; |
fbb5b7ae | 1307 | break; |
ebf99093 TZ |
1308 | } |
1309 | ||
1310 | *ppos += ret; | |
1311 | if (ret > len) | |
1312 | len = 0; | |
1313 | else | |
1314 | len -= ret; | |
1315 | spliced += nonpad_ret; | |
1316 | nonpad_ret = 0; | |
1317 | } | |
1318 | ||
1319 | if (spliced) | |
1320 | return spliced; | |
1321 | ||
1322 | return ret; | |
221415d7 JA |
1323 | } |
1324 | ||
15ad7cdc | 1325 | const struct file_operations relay_file_operations = { |
b86ff981 JA |
1326 | .open = relay_file_open, |
1327 | .poll = relay_file_poll, | |
1328 | .mmap = relay_file_mmap, | |
1329 | .read = relay_file_read, | |
1330 | .llseek = no_llseek, | |
1331 | .release = relay_file_release, | |
ebf99093 | 1332 | .splice_read = relay_file_splice_read, |
b86ff981 JA |
1333 | }; |
1334 | EXPORT_SYMBOL_GPL(relay_file_operations); |