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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
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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)
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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>
18#include <linux/module.h>
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>
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MD
25
26/* list of open channels, for cpu hotplug */
27static DEFINE_MUTEX(relay_channels_mutex);
28static LIST_HEAD(relay_channels);
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29
30/*
31 * close() vm_op implementation for relay file mapping.
32 */
33static 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 42static int relay_buf_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
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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
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58}
59
60/*
61 * vm_ops for relay file mappings.
62 */
63static struct vm_operations_struct relay_file_mmap_ops = {
a1e09612 64 .fault = relay_buf_fault,
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65 .close = relay_file_mmap_close,
66};
67
68ab3d88
MH
68/*
69 * allocate an array of pointers of struct page
70 */
71static struct page **relay_alloc_page_array(unsigned int n_pages)
72{
73 struct page **array;
74 size_t pa_size = n_pages * sizeof(struct page *);
75
76 if (pa_size > PAGE_SIZE) {
77 array = vmalloc(pa_size);
78 if (array)
79 memset(array, 0, pa_size);
80 } else {
81 array = kzalloc(pa_size, GFP_KERNEL);
82 }
83 return array;
84}
85
86/*
87 * free an array of pointers of struct page
88 */
89static void relay_free_page_array(struct page **array)
90{
91 if (is_vmalloc_addr(array))
92 vfree(array);
93 else
94 kfree(array);
95}
96
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97/**
98 * relay_mmap_buf: - mmap channel buffer to process address space
99 * @buf: relay channel buffer
100 * @vma: vm_area_struct describing memory to be mapped
101 *
102 * Returns 0 if ok, negative on error
103 *
104 * Caller should already have grabbed mmap_sem.
105 */
01c55ed3 106static int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma)
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107{
108 unsigned long length = vma->vm_end - vma->vm_start;
109 struct file *filp = vma->vm_file;
110
111 if (!buf)
112 return -EBADF;
113
114 if (length != (unsigned long)buf->chan->alloc_size)
115 return -EINVAL;
116
117 vma->vm_ops = &relay_file_mmap_ops;
2f98735c 118 vma->vm_flags |= VM_DONTEXPAND;
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119 vma->vm_private_data = buf;
120 buf->chan->cb->buf_mapped(buf, filp);
121
122 return 0;
123}
124
125/**
126 * relay_alloc_buf - allocate a channel buffer
127 * @buf: the buffer struct
128 * @size: total size of the buffer
129 *
4c78a663 130 * Returns a pointer to the resulting buffer, %NULL if unsuccessful. The
221415d7 131 * passed in size will get page aligned, if it isn't already.
b86ff981 132 */
221415d7 133static void *relay_alloc_buf(struct rchan_buf *buf, size_t *size)
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134{
135 void *mem;
136 unsigned int i, j, n_pages;
137
221415d7
JA
138 *size = PAGE_ALIGN(*size);
139 n_pages = *size >> PAGE_SHIFT;
b86ff981 140
68ab3d88 141 buf->page_array = relay_alloc_page_array(n_pages);
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142 if (!buf->page_array)
143 return NULL;
144
145 for (i = 0; i < n_pages; i++) {
146 buf->page_array[i] = alloc_page(GFP_KERNEL);
147 if (unlikely(!buf->page_array[i]))
148 goto depopulate;
ebf99093 149 set_page_private(buf->page_array[i], (unsigned long)buf);
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JA
150 }
151 mem = vmap(buf->page_array, n_pages, VM_MAP, PAGE_KERNEL);
152 if (!mem)
153 goto depopulate;
154
221415d7 155 memset(mem, 0, *size);
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156 buf->page_count = n_pages;
157 return mem;
158
159depopulate:
160 for (j = 0; j < i; j++)
161 __free_page(buf->page_array[j]);
68ab3d88 162 relay_free_page_array(buf->page_array);
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163 return NULL;
164}
165
166/**
167 * relay_create_buf - allocate and initialize a channel buffer
4c78a663 168 * @chan: the relay channel
b86ff981 169 *
4c78a663 170 * Returns channel buffer if successful, %NULL otherwise.
b86ff981 171 */
01c55ed3 172static struct rchan_buf *relay_create_buf(struct rchan *chan)
b86ff981 173{
cd861280 174 struct rchan_buf *buf = kzalloc(sizeof(struct rchan_buf), GFP_KERNEL);
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175 if (!buf)
176 return NULL;
177
178 buf->padding = kmalloc(chan->n_subbufs * sizeof(size_t *), GFP_KERNEL);
179 if (!buf->padding)
180 goto free_buf;
181
221415d7 182 buf->start = relay_alloc_buf(buf, &chan->alloc_size);
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183 if (!buf->start)
184 goto free_buf;
185
186 buf->chan = chan;
187 kref_get(&buf->chan->kref);
188 return buf;
189
190free_buf:
191 kfree(buf->padding);
192 kfree(buf);
193 return NULL;
194}
195
196/**
197 * relay_destroy_channel - free the channel struct
4c78a663 198 * @kref: target kernel reference that contains the relay channel
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199 *
200 * Should only be called from kref_put().
201 */
01c55ed3 202static void relay_destroy_channel(struct kref *kref)
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203{
204 struct rchan *chan = container_of(kref, struct rchan, kref);
205 kfree(chan);
206}
207
208/**
209 * relay_destroy_buf - destroy an rchan_buf struct and associated buffer
210 * @buf: the buffer struct
211 */
01c55ed3 212static void relay_destroy_buf(struct rchan_buf *buf)
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213{
214 struct rchan *chan = buf->chan;
215 unsigned int i;
216
217 if (likely(buf->start)) {
218 vunmap(buf->start);
219 for (i = 0; i < buf->page_count; i++)
220 __free_page(buf->page_array[i]);
68ab3d88 221 relay_free_page_array(buf->page_array);
b86ff981 222 }
23c88752 223 chan->buf[buf->cpu] = NULL;
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224 kfree(buf->padding);
225 kfree(buf);
226 kref_put(&chan->kref, relay_destroy_channel);
227}
228
229/**
230 * relay_remove_buf - remove a channel buffer
4c78a663 231 * @kref: target kernel reference that contains the relay buffer
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232 *
233 * Removes the file from the fileystem, which also frees the
234 * rchan_buf_struct and the channel buffer. Should only be called from
235 * kref_put().
236 */
01c55ed3 237static void relay_remove_buf(struct kref *kref)
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238{
239 struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref);
240 buf->chan->cb->remove_buf_file(buf->dentry);
241 relay_destroy_buf(buf);
242}
243
244/**
245 * relay_buf_empty - boolean, is the channel buffer empty?
246 * @buf: channel buffer
247 *
248 * Returns 1 if the buffer is empty, 0 otherwise.
249 */
01c55ed3 250static int relay_buf_empty(struct rchan_buf *buf)
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251{
252 return (buf->subbufs_produced - buf->subbufs_consumed) ? 0 : 1;
253}
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254
255/**
256 * relay_buf_full - boolean, is the channel buffer full?
257 * @buf: channel buffer
258 *
259 * Returns 1 if the buffer is full, 0 otherwise.
260 */
261int relay_buf_full(struct rchan_buf *buf)
262{
263 size_t ready = buf->subbufs_produced - buf->subbufs_consumed;
264 return (ready >= buf->chan->n_subbufs) ? 1 : 0;
265}
266EXPORT_SYMBOL_GPL(relay_buf_full);
267
268/*
269 * High-level relay kernel API and associated functions.
270 */
271
272/*
273 * rchan_callback implementations defining default channel behavior. Used
274 * in place of corresponding NULL values in client callback struct.
275 */
276
277/*
278 * subbuf_start() default callback. Does nothing.
279 */
280static int subbuf_start_default_callback (struct rchan_buf *buf,
281 void *subbuf,
282 void *prev_subbuf,
283 size_t prev_padding)
284{
285 if (relay_buf_full(buf))
286 return 0;
287
288 return 1;
289}
290
291/*
292 * buf_mapped() default callback. Does nothing.
293 */
294static void buf_mapped_default_callback(struct rchan_buf *buf,
295 struct file *filp)
296{
297}
298
299/*
300 * buf_unmapped() default callback. Does nothing.
301 */
302static void buf_unmapped_default_callback(struct rchan_buf *buf,
303 struct file *filp)
304{
305}
306
307/*
308 * create_buf_file_create() default callback. Does nothing.
309 */
310static struct dentry *create_buf_file_default_callback(const char *filename,
311 struct dentry *parent,
312 int mode,
313 struct rchan_buf *buf,
314 int *is_global)
315{
316 return NULL;
317}
318
319/*
320 * remove_buf_file() default callback. Does nothing.
321 */
322static int remove_buf_file_default_callback(struct dentry *dentry)
323{
324 return -EINVAL;
325}
326
327/* relay channel default callbacks */
328static struct rchan_callbacks default_channel_callbacks = {
329 .subbuf_start = subbuf_start_default_callback,
330 .buf_mapped = buf_mapped_default_callback,
331 .buf_unmapped = buf_unmapped_default_callback,
332 .create_buf_file = create_buf_file_default_callback,
333 .remove_buf_file = remove_buf_file_default_callback,
334};
335
336/**
337 * wakeup_readers - wake up readers waiting on a channel
9a9136e2 338 * @data: contains the channel buffer
b86ff981 339 *
7c9cb383 340 * This is the timer function used to defer reader waking.
b86ff981 341 */
7c9cb383 342static void wakeup_readers(unsigned long data)
b86ff981 343{
7c9cb383 344 struct rchan_buf *buf = (struct rchan_buf *)data;
b86ff981
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345 wake_up_interruptible(&buf->read_wait);
346}
347
348/**
349 * __relay_reset - reset a channel buffer
350 * @buf: the channel buffer
351 * @init: 1 if this is a first-time initialization
352 *
72fd4a35 353 * See relay_reset() for description of effect.
b86ff981 354 */
192636ad 355static void __relay_reset(struct rchan_buf *buf, unsigned int init)
b86ff981
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356{
357 size_t i;
358
359 if (init) {
360 init_waitqueue_head(&buf->read_wait);
361 kref_init(&buf->kref);
7c9cb383
TZ
362 setup_timer(&buf->timer, wakeup_readers, (unsigned long)buf);
363 } else
364 del_timer_sync(&buf->timer);
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365
366 buf->subbufs_produced = 0;
367 buf->subbufs_consumed = 0;
368 buf->bytes_consumed = 0;
369 buf->finalized = 0;
370 buf->data = buf->start;
371 buf->offset = 0;
372
373 for (i = 0; i < buf->chan->n_subbufs; i++)
374 buf->padding[i] = 0;
375
376 buf->chan->cb->subbuf_start(buf, buf->data, NULL, 0);
377}
378
379/**
380 * relay_reset - reset the channel
381 * @chan: the channel
382 *
383 * This has the effect of erasing all data from all channel buffers
384 * and restarting the channel in its initial state. The buffers
385 * are not freed, so any mappings are still in effect.
386 *
72fd4a35 387 * NOTE. Care should be taken that the channel isn't actually
b86ff981
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388 * being used by anything when this call is made.
389 */
390void relay_reset(struct rchan *chan)
391{
392 unsigned int i;
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393
394 if (!chan)
395 return;
396
1bfbc608 397 if (chan->is_global && chan->buf[0]) {
23c88752
MD
398 __relay_reset(chan->buf[0], 0);
399 return;
b86ff981 400 }
23c88752
MD
401
402 mutex_lock(&relay_channels_mutex);
98ba4031 403 for_each_possible_cpu(i)
23c88752
MD
404 if (chan->buf[i])
405 __relay_reset(chan->buf[i], 0);
406 mutex_unlock(&relay_channels_mutex);
b86ff981
JA
407}
408EXPORT_SYMBOL_GPL(relay_reset);
409
20d8b67c
EGM
410static inline void relay_set_buf_dentry(struct rchan_buf *buf,
411 struct dentry *dentry)
412{
413 buf->dentry = dentry;
414 buf->dentry->d_inode->i_size = buf->early_bytes;
415}
416
417static struct dentry *relay_create_buf_file(struct rchan *chan,
418 struct rchan_buf *buf,
419 unsigned int cpu)
420{
421 struct dentry *dentry;
422 char *tmpname;
423
424 tmpname = kzalloc(NAME_MAX + 1, GFP_KERNEL);
425 if (!tmpname)
426 return NULL;
427 snprintf(tmpname, NAME_MAX, "%s%d", chan->base_filename, cpu);
428
429 /* Create file in fs */
430 dentry = chan->cb->create_buf_file(tmpname, chan->parent,
431 S_IRUSR, buf,
432 &chan->is_global);
433
434 kfree(tmpname);
435
436 return dentry;
437}
438
4c78a663 439/*
b86ff981
JA
440 * relay_open_buf - create a new relay channel buffer
441 *
23c88752 442 * used by relay_open() and CPU hotplug.
b86ff981 443 */
23c88752 444static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu)
b86ff981 445{
23c88752 446 struct rchan_buf *buf = NULL;
b86ff981
JA
447 struct dentry *dentry;
448
23c88752 449 if (chan->is_global)
b86ff981
JA
450 return chan->buf[0];
451
452 buf = relay_create_buf(chan);
453 if (!buf)
20d8b67c
EGM
454 return NULL;
455
456 if (chan->has_base_filename) {
457 dentry = relay_create_buf_file(chan, buf, cpu);
458 if (!dentry)
459 goto free_buf;
460 relay_set_buf_dentry(buf, dentry);
461 }
23c88752
MD
462
463 buf->cpu = cpu;
464 __relay_reset(buf, 1);
b86ff981 465
23c88752
MD
466 if(chan->is_global) {
467 chan->buf[0] = buf;
468 buf->cpu = 0;
469 }
470
20d8b67c 471 return buf;
23c88752
MD
472
473free_buf:
474 relay_destroy_buf(buf);
20d8b67c 475 return NULL;
b86ff981
JA
476}
477
478/**
479 * relay_close_buf - close a channel buffer
480 * @buf: channel buffer
481 *
482 * Marks the buffer finalized and restores the default callbacks.
483 * The channel buffer and channel buffer data structure are then freed
484 * automatically when the last reference is given up.
485 */
192636ad 486static void relay_close_buf(struct rchan_buf *buf)
b86ff981
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487{
488 buf->finalized = 1;
7c9cb383 489 del_timer_sync(&buf->timer);
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490 kref_put(&buf->kref, relay_remove_buf);
491}
492
192636ad 493static void setup_callbacks(struct rchan *chan,
b86ff981
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494 struct rchan_callbacks *cb)
495{
496 if (!cb) {
497 chan->cb = &default_channel_callbacks;
498 return;
499 }
500
501 if (!cb->subbuf_start)
502 cb->subbuf_start = subbuf_start_default_callback;
503 if (!cb->buf_mapped)
504 cb->buf_mapped = buf_mapped_default_callback;
505 if (!cb->buf_unmapped)
506 cb->buf_unmapped = buf_unmapped_default_callback;
507 if (!cb->create_buf_file)
508 cb->create_buf_file = create_buf_file_default_callback;
509 if (!cb->remove_buf_file)
510 cb->remove_buf_file = remove_buf_file_default_callback;
511 chan->cb = cb;
512}
513
23c88752 514/**
23c88752
MD
515 * relay_hotcpu_callback - CPU hotplug callback
516 * @nb: notifier block
517 * @action: hotplug action to take
518 * @hcpu: CPU number
519 *
05fb6bf0 520 * Returns the success/failure of the operation. (%NOTIFY_OK, %NOTIFY_BAD)
23c88752
MD
521 */
522static int __cpuinit relay_hotcpu_callback(struct notifier_block *nb,
523 unsigned long action,
524 void *hcpu)
525{
526 unsigned int hotcpu = (unsigned long)hcpu;
527 struct rchan *chan;
528
529 switch(action) {
530 case CPU_UP_PREPARE:
8bb78442 531 case CPU_UP_PREPARE_FROZEN:
23c88752
MD
532 mutex_lock(&relay_channels_mutex);
533 list_for_each_entry(chan, &relay_channels, list) {
534 if (chan->buf[hotcpu])
535 continue;
536 chan->buf[hotcpu] = relay_open_buf(chan, hotcpu);
537 if(!chan->buf[hotcpu]) {
538 printk(KERN_ERR
539 "relay_hotcpu_callback: cpu %d buffer "
540 "creation failed\n", hotcpu);
541 mutex_unlock(&relay_channels_mutex);
542 return NOTIFY_BAD;
543 }
544 }
545 mutex_unlock(&relay_channels_mutex);
546 break;
547 case CPU_DEAD:
8bb78442 548 case CPU_DEAD_FROZEN:
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MD
549 /* No need to flush the cpu : will be flushed upon
550 * final relay_flush() call. */
551 break;
552 }
553 return NOTIFY_OK;
554}
555
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556/**
557 * relay_open - create a new relay channel
20d8b67c
EGM
558 * @base_filename: base name of files to create, %NULL for buffering only
559 * @parent: dentry of parent directory, %NULL for root directory or buffer
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560 * @subbuf_size: size of sub-buffers
561 * @n_subbufs: number of sub-buffers
562 * @cb: client callback functions
23c88752 563 * @private_data: user-defined data
b86ff981 564 *
4c78a663 565 * Returns channel pointer if successful, %NULL otherwise.
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566 *
567 * Creates a channel buffer for each cpu using the sizes and
568 * attributes specified. The created channel buffer files
569 * will be named base_filename0...base_filenameN-1. File
72fd4a35 570 * permissions will be %S_IRUSR.
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571 */
572struct rchan *relay_open(const char *base_filename,
573 struct dentry *parent,
574 size_t subbuf_size,
575 size_t n_subbufs,
23c88752
MD
576 struct rchan_callbacks *cb,
577 void *private_data)
b86ff981
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578{
579 unsigned int i;
580 struct rchan *chan;
b86ff981
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581
582 if (!(subbuf_size && n_subbufs))
583 return NULL;
584
cd861280 585 chan = kzalloc(sizeof(struct rchan), GFP_KERNEL);
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586 if (!chan)
587 return NULL;
588
589 chan->version = RELAYFS_CHANNEL_VERSION;
590 chan->n_subbufs = n_subbufs;
591 chan->subbuf_size = subbuf_size;
592 chan->alloc_size = FIX_SIZE(subbuf_size * n_subbufs);
23c88752
MD
593 chan->parent = parent;
594 chan->private_data = private_data;
20d8b67c
EGM
595 if (base_filename) {
596 chan->has_base_filename = 1;
597 strlcpy(chan->base_filename, base_filename, NAME_MAX);
598 }
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599 setup_callbacks(chan, cb);
600 kref_init(&chan->kref);
601
23c88752 602 mutex_lock(&relay_channels_mutex);
b86ff981 603 for_each_online_cpu(i) {
23c88752 604 chan->buf[i] = relay_open_buf(chan, i);
b86ff981
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605 if (!chan->buf[i])
606 goto free_bufs;
b86ff981 607 }
23c88752
MD
608 list_add(&chan->list, &relay_channels);
609 mutex_unlock(&relay_channels_mutex);
b86ff981 610
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611 return chan;
612
613free_bufs:
98ba4031
LJ
614 for_each_possible_cpu(i) {
615 if (chan->buf[i])
616 relay_close_buf(chan->buf[i]);
b86ff981 617 }
b86ff981 618
b86ff981 619 kref_put(&chan->kref, relay_destroy_channel);
23c88752 620 mutex_unlock(&relay_channels_mutex);
b86ff981
JA
621 return NULL;
622}
623EXPORT_SYMBOL_GPL(relay_open);
624
20d8b67c
EGM
625struct rchan_percpu_buf_dispatcher {
626 struct rchan_buf *buf;
627 struct dentry *dentry;
628};
629
630/* Called in atomic context. */
631static void __relay_set_buf_dentry(void *info)
632{
633 struct rchan_percpu_buf_dispatcher *p = info;
634
635 relay_set_buf_dentry(p->buf, p->dentry);
636}
637
638/**
639 * relay_late_setup_files - triggers file creation
640 * @chan: channel to operate on
641 * @base_filename: base name of files to create
642 * @parent: dentry of parent directory, %NULL for root directory
643 *
644 * Returns 0 if successful, non-zero otherwise.
645 *
646 * Use to setup files for a previously buffer-only channel.
647 * Useful to do early tracing in kernel, before VFS is up, for example.
648 */
649int relay_late_setup_files(struct rchan *chan,
650 const char *base_filename,
651 struct dentry *parent)
652{
653 int err = 0;
654 unsigned int i, curr_cpu;
655 unsigned long flags;
656 struct dentry *dentry;
657 struct rchan_percpu_buf_dispatcher disp;
658
659 if (!chan || !base_filename)
660 return -EINVAL;
661
662 strlcpy(chan->base_filename, base_filename, NAME_MAX);
663
664 mutex_lock(&relay_channels_mutex);
665 /* Is chan already set up? */
666 if (unlikely(chan->has_base_filename))
667 return -EEXIST;
668 chan->has_base_filename = 1;
669 chan->parent = parent;
670 curr_cpu = get_cpu();
671 /*
672 * The CPU hotplug notifier ran before us and created buffers with
673 * no files associated. So it's safe to call relay_setup_buf_file()
674 * on all currently online CPUs.
675 */
676 for_each_online_cpu(i) {
677 if (unlikely(!chan->buf[i])) {
678 printk(KERN_ERR "relay_late_setup_files: CPU %u "
679 "has no buffer, it must have!\n", i);
680 BUG();
681 err = -EINVAL;
682 break;
683 }
684
685 dentry = relay_create_buf_file(chan, chan->buf[i], i);
686 if (unlikely(!dentry)) {
687 err = -EINVAL;
688 break;
689 }
690
691 if (curr_cpu == i) {
692 local_irq_save(flags);
693 relay_set_buf_dentry(chan->buf[i], dentry);
694 local_irq_restore(flags);
695 } else {
696 disp.buf = chan->buf[i];
697 disp.dentry = dentry;
698 smp_mb();
699 /* relay_channels_mutex must be held, so wait. */
700 err = smp_call_function_single(i,
701 __relay_set_buf_dentry,
702 &disp, 1);
703 }
704 if (unlikely(err))
705 break;
706 }
707 put_cpu();
708 mutex_unlock(&relay_channels_mutex);
709
710 return err;
711}
712
b86ff981
JA
713/**
714 * relay_switch_subbuf - switch to a new sub-buffer
715 * @buf: channel buffer
716 * @length: size of current event
717 *
718 * Returns either the length passed in or 0 if full.
719 *
720 * Performs sub-buffer-switch tasks such as invoking callbacks,
721 * updating padding counts, waking up readers, etc.
722 */
723size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length)
724{
725 void *old, *new;
726 size_t old_subbuf, new_subbuf;
727
728 if (unlikely(length > buf->chan->subbuf_size))
729 goto toobig;
730
731 if (buf->offset != buf->chan->subbuf_size + 1) {
732 buf->prev_padding = buf->chan->subbuf_size - buf->offset;
733 old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs;
734 buf->padding[old_subbuf] = buf->prev_padding;
735 buf->subbufs_produced++;
20d8b67c
EGM
736 if (buf->dentry)
737 buf->dentry->d_inode->i_size +=
738 buf->chan->subbuf_size -
739 buf->padding[old_subbuf];
740 else
741 buf->early_bytes += buf->chan->subbuf_size -
742 buf->padding[old_subbuf];
221415d7 743 smp_mb();
7c9cb383
TZ
744 if (waitqueue_active(&buf->read_wait))
745 /*
746 * Calling wake_up_interruptible() from here
747 * will deadlock if we happen to be logging
748 * from the scheduler (trying to re-grab
749 * rq->lock), so defer it.
750 */
751 __mod_timer(&buf->timer, jiffies + 1);
b86ff981
JA
752 }
753
754 old = buf->data;
755 new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs;
756 new = buf->start + new_subbuf * buf->chan->subbuf_size;
757 buf->offset = 0;
758 if (!buf->chan->cb->subbuf_start(buf, new, old, buf->prev_padding)) {
759 buf->offset = buf->chan->subbuf_size + 1;
760 return 0;
761 }
762 buf->data = new;
763 buf->padding[new_subbuf] = 0;
764
765 if (unlikely(length + buf->offset > buf->chan->subbuf_size))
766 goto toobig;
767
768 return length;
769
770toobig:
771 buf->chan->last_toobig = length;
772 return 0;
773}
774EXPORT_SYMBOL_GPL(relay_switch_subbuf);
775
776/**
777 * relay_subbufs_consumed - update the buffer's sub-buffers-consumed count
778 * @chan: the channel
779 * @cpu: the cpu associated with the channel buffer to update
780 * @subbufs_consumed: number of sub-buffers to add to current buf's count
781 *
782 * Adds to the channel buffer's consumed sub-buffer count.
783 * subbufs_consumed should be the number of sub-buffers newly consumed,
784 * not the total consumed.
785 *
72fd4a35 786 * NOTE. Kernel clients don't need to call this function if the channel
b86ff981
JA
787 * mode is 'overwrite'.
788 */
789void relay_subbufs_consumed(struct rchan *chan,
790 unsigned int cpu,
791 size_t subbufs_consumed)
792{
793 struct rchan_buf *buf;
794
795 if (!chan)
796 return;
797
798 if (cpu >= NR_CPUS || !chan->buf[cpu])
799 return;
800
801 buf = chan->buf[cpu];
802 buf->subbufs_consumed += subbufs_consumed;
803 if (buf->subbufs_consumed > buf->subbufs_produced)
804 buf->subbufs_consumed = buf->subbufs_produced;
805}
806EXPORT_SYMBOL_GPL(relay_subbufs_consumed);
807
808/**
809 * relay_close - close the channel
810 * @chan: the channel
811 *
812 * Closes all channel buffers and frees the channel.
813 */
814void relay_close(struct rchan *chan)
815{
816 unsigned int i;
b86ff981
JA
817
818 if (!chan)
819 return;
820
23c88752
MD
821 mutex_lock(&relay_channels_mutex);
822 if (chan->is_global && chan->buf[0])
823 relay_close_buf(chan->buf[0]);
824 else
825 for_each_possible_cpu(i)
826 if (chan->buf[i])
827 relay_close_buf(chan->buf[i]);
b86ff981
JA
828
829 if (chan->last_toobig)
830 printk(KERN_WARNING "relay: one or more items not logged "
831 "[item size (%Zd) > sub-buffer size (%Zd)]\n",
832 chan->last_toobig, chan->subbuf_size);
833
23c88752 834 list_del(&chan->list);
b86ff981 835 kref_put(&chan->kref, relay_destroy_channel);
23c88752 836 mutex_unlock(&relay_channels_mutex);
b86ff981
JA
837}
838EXPORT_SYMBOL_GPL(relay_close);
839
840/**
841 * relay_flush - close the channel
842 * @chan: the channel
843 *
4c78a663 844 * Flushes all channel buffers, i.e. forces buffer switch.
b86ff981
JA
845 */
846void relay_flush(struct rchan *chan)
847{
848 unsigned int i;
b86ff981
JA
849
850 if (!chan)
851 return;
852
23c88752
MD
853 if (chan->is_global && chan->buf[0]) {
854 relay_switch_subbuf(chan->buf[0], 0);
855 return;
b86ff981 856 }
23c88752
MD
857
858 mutex_lock(&relay_channels_mutex);
859 for_each_possible_cpu(i)
860 if (chan->buf[i])
861 relay_switch_subbuf(chan->buf[i], 0);
862 mutex_unlock(&relay_channels_mutex);
b86ff981
JA
863}
864EXPORT_SYMBOL_GPL(relay_flush);
865
866/**
867 * relay_file_open - open file op for relay files
868 * @inode: the inode
869 * @filp: the file
870 *
871 * Increments the channel buffer refcount.
872 */
873static int relay_file_open(struct inode *inode, struct file *filp)
874{
8e18e294 875 struct rchan_buf *buf = inode->i_private;
b86ff981
JA
876 kref_get(&buf->kref);
877 filp->private_data = buf;
878
37529fe9 879 return nonseekable_open(inode, filp);
b86ff981
JA
880}
881
882/**
883 * relay_file_mmap - mmap file op for relay files
884 * @filp: the file
885 * @vma: the vma describing what to map
886 *
72fd4a35 887 * Calls upon relay_mmap_buf() to map the file into user space.
b86ff981
JA
888 */
889static int relay_file_mmap(struct file *filp, struct vm_area_struct *vma)
890{
891 struct rchan_buf *buf = filp->private_data;
892 return relay_mmap_buf(buf, vma);
893}
894
895/**
896 * relay_file_poll - poll file op for relay files
897 * @filp: the file
898 * @wait: poll table
899 *
900 * Poll implemention.
901 */
902static unsigned int relay_file_poll(struct file *filp, poll_table *wait)
903{
904 unsigned int mask = 0;
905 struct rchan_buf *buf = filp->private_data;
906
907 if (buf->finalized)
908 return POLLERR;
909
910 if (filp->f_mode & FMODE_READ) {
911 poll_wait(filp, &buf->read_wait, wait);
912 if (!relay_buf_empty(buf))
913 mask |= POLLIN | POLLRDNORM;
914 }
915
916 return mask;
917}
918
919/**
920 * relay_file_release - release file op for relay files
921 * @inode: the inode
922 * @filp: the file
923 *
924 * Decrements the channel refcount, as the filesystem is
925 * no longer using it.
926 */
927static int relay_file_release(struct inode *inode, struct file *filp)
928{
929 struct rchan_buf *buf = filp->private_data;
930 kref_put(&buf->kref, relay_remove_buf);
931
932 return 0;
933}
934
4c78a663 935/*
b86ff981
JA
936 * relay_file_read_consume - update the consumed count for the buffer
937 */
938static void relay_file_read_consume(struct rchan_buf *buf,
939 size_t read_pos,
940 size_t bytes_consumed)
941{
942 size_t subbuf_size = buf->chan->subbuf_size;
943 size_t n_subbufs = buf->chan->n_subbufs;
944 size_t read_subbuf;
945
32194450
TZ
946 if (buf->subbufs_produced == buf->subbufs_consumed &&
947 buf->offset == buf->bytes_consumed)
948 return;
949
b86ff981
JA
950 if (buf->bytes_consumed + bytes_consumed > subbuf_size) {
951 relay_subbufs_consumed(buf->chan, buf->cpu, 1);
952 buf->bytes_consumed = 0;
953 }
954
955 buf->bytes_consumed += bytes_consumed;
a66e356c
MH
956 if (!read_pos)
957 read_subbuf = buf->subbufs_consumed % n_subbufs;
958 else
959 read_subbuf = read_pos / buf->chan->subbuf_size;
b86ff981
JA
960 if (buf->bytes_consumed + buf->padding[read_subbuf] == subbuf_size) {
961 if ((read_subbuf == buf->subbufs_produced % n_subbufs) &&
962 (buf->offset == subbuf_size))
963 return;
964 relay_subbufs_consumed(buf->chan, buf->cpu, 1);
965 buf->bytes_consumed = 0;
966 }
967}
968
4c78a663 969/*
b86ff981
JA
970 * relay_file_read_avail - boolean, are there unconsumed bytes available?
971 */
972static int relay_file_read_avail(struct rchan_buf *buf, size_t read_pos)
973{
b86ff981
JA
974 size_t subbuf_size = buf->chan->subbuf_size;
975 size_t n_subbufs = buf->chan->n_subbufs;
221415d7
JA
976 size_t produced = buf->subbufs_produced;
977 size_t consumed = buf->subbufs_consumed;
b86ff981 978
221415d7 979 relay_file_read_consume(buf, read_pos, 0);
b86ff981 980
32194450
TZ
981 consumed = buf->subbufs_consumed;
982
221415d7
JA
983 if (unlikely(buf->offset > subbuf_size)) {
984 if (produced == consumed)
985 return 0;
986 return 1;
b86ff981
JA
987 }
988
221415d7 989 if (unlikely(produced - consumed >= n_subbufs)) {
a66e356c 990 consumed = produced - n_subbufs + 1;
221415d7 991 buf->subbufs_consumed = consumed;
a66e356c 992 buf->bytes_consumed = 0;
221415d7 993 }
1bfbc608 994
221415d7
JA
995 produced = (produced % n_subbufs) * subbuf_size + buf->offset;
996 consumed = (consumed % n_subbufs) * subbuf_size + buf->bytes_consumed;
997
998 if (consumed > produced)
999 produced += n_subbufs * subbuf_size;
1bfbc608 1000
32194450
TZ
1001 if (consumed == produced) {
1002 if (buf->offset == subbuf_size &&
1003 buf->subbufs_produced > buf->subbufs_consumed)
1004 return 1;
b86ff981 1005 return 0;
32194450 1006 }
b86ff981 1007
b86ff981
JA
1008 return 1;
1009}
1010
1011/**
1012 * relay_file_read_subbuf_avail - return bytes available in sub-buffer
4c78a663
RD
1013 * @read_pos: file read position
1014 * @buf: relay channel buffer
b86ff981
JA
1015 */
1016static size_t relay_file_read_subbuf_avail(size_t read_pos,
1017 struct rchan_buf *buf)
1018{
1019 size_t padding, avail = 0;
1020 size_t read_subbuf, read_offset, write_subbuf, write_offset;
1021 size_t subbuf_size = buf->chan->subbuf_size;
1022
1023 write_subbuf = (buf->data - buf->start) / subbuf_size;
1024 write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset;
1025 read_subbuf = read_pos / subbuf_size;
1026 read_offset = read_pos % subbuf_size;
1027 padding = buf->padding[read_subbuf];
1028
1029 if (read_subbuf == write_subbuf) {
1030 if (read_offset + padding < write_offset)
1031 avail = write_offset - (read_offset + padding);
1032 } else
1033 avail = (subbuf_size - padding) - read_offset;
1034
1035 return avail;
1036}
1037
1038/**
1039 * relay_file_read_start_pos - find the first available byte to read
4c78a663
RD
1040 * @read_pos: file read position
1041 * @buf: relay channel buffer
b86ff981 1042 *
72fd4a35 1043 * If the @read_pos is in the middle of padding, return the
b86ff981
JA
1044 * position of the first actually available byte, otherwise
1045 * return the original value.
1046 */
1047static size_t relay_file_read_start_pos(size_t read_pos,
1048 struct rchan_buf *buf)
1049{
1050 size_t read_subbuf, padding, padding_start, padding_end;
1051 size_t subbuf_size = buf->chan->subbuf_size;
1052 size_t n_subbufs = buf->chan->n_subbufs;
8d62fdeb 1053 size_t consumed = buf->subbufs_consumed % n_subbufs;
b86ff981 1054
8d62fdeb
DW
1055 if (!read_pos)
1056 read_pos = consumed * subbuf_size + buf->bytes_consumed;
b86ff981
JA
1057 read_subbuf = read_pos / subbuf_size;
1058 padding = buf->padding[read_subbuf];
1059 padding_start = (read_subbuf + 1) * subbuf_size - padding;
1060 padding_end = (read_subbuf + 1) * subbuf_size;
1061 if (read_pos >= padding_start && read_pos < padding_end) {
1062 read_subbuf = (read_subbuf + 1) % n_subbufs;
1063 read_pos = read_subbuf * subbuf_size;
1064 }
1065
1066 return read_pos;
1067}
1068
1069/**
1070 * relay_file_read_end_pos - return the new read position
4c78a663
RD
1071 * @read_pos: file read position
1072 * @buf: relay channel buffer
1073 * @count: number of bytes to be read
b86ff981
JA
1074 */
1075static size_t relay_file_read_end_pos(struct rchan_buf *buf,
1076 size_t read_pos,
1077 size_t count)
1078{
1079 size_t read_subbuf, padding, end_pos;
1080 size_t subbuf_size = buf->chan->subbuf_size;
1081 size_t n_subbufs = buf->chan->n_subbufs;
1082
1083 read_subbuf = read_pos / subbuf_size;
1084 padding = buf->padding[read_subbuf];
1085 if (read_pos % subbuf_size + count + padding == subbuf_size)
1086 end_pos = (read_subbuf + 1) * subbuf_size;
1087 else
1088 end_pos = read_pos + count;
1089 if (end_pos >= subbuf_size * n_subbufs)
1090 end_pos = 0;
1091
1092 return end_pos;
1093}
1094
4c78a663 1095/*
6dac40a7 1096 * subbuf_read_actor - read up to one subbuf's worth of data
b86ff981 1097 */
6dac40a7
TZ
1098static int subbuf_read_actor(size_t read_start,
1099 struct rchan_buf *buf,
1100 size_t avail,
1101 read_descriptor_t *desc,
1102 read_actor_t actor)
b86ff981 1103{
b86ff981 1104 void *from;
6dac40a7 1105 int ret = 0;
b86ff981
JA
1106
1107 from = buf->start + read_start;
6dac40a7 1108 ret = avail;
ba2397ef 1109 if (copy_to_user(desc->arg.buf, from, avail)) {
6dac40a7
TZ
1110 desc->error = -EFAULT;
1111 ret = 0;
b86ff981 1112 }
6dac40a7
TZ
1113 desc->arg.data += ret;
1114 desc->written += ret;
1115 desc->count -= ret;
1116
b86ff981
JA
1117 return ret;
1118}
1119
6dac40a7
TZ
1120typedef int (*subbuf_actor_t) (size_t read_start,
1121 struct rchan_buf *buf,
1122 size_t avail,
1123 read_descriptor_t *desc,
1124 read_actor_t actor);
1125
4c78a663 1126/*
6dac40a7
TZ
1127 * relay_file_read_subbufs - read count bytes, bridging subbuf boundaries
1128 */
192636ad
AM
1129static ssize_t relay_file_read_subbufs(struct file *filp, loff_t *ppos,
1130 subbuf_actor_t subbuf_actor,
1131 read_actor_t actor,
1132 read_descriptor_t *desc)
221415d7 1133{
6dac40a7
TZ
1134 struct rchan_buf *buf = filp->private_data;
1135 size_t read_start, avail;
6dac40a7 1136 int ret;
221415d7 1137
ba2397ef 1138 if (!desc->count)
221415d7
JA
1139 return 0;
1140
f3a43f3f 1141 mutex_lock(&filp->f_path.dentry->d_inode->i_mutex);
221415d7 1142 do {
6dac40a7
TZ
1143 if (!relay_file_read_avail(buf, *ppos))
1144 break;
1145
1146 read_start = relay_file_read_start_pos(*ppos, buf);
1147 avail = relay_file_read_subbuf_avail(read_start, buf);
1148 if (!avail)
221415d7 1149 break;
221415d7 1150
ba2397ef
AV
1151 avail = min(desc->count, avail);
1152 ret = subbuf_actor(read_start, buf, avail, desc, actor);
1153 if (desc->error < 0)
6dac40a7
TZ
1154 break;
1155
1156 if (ret) {
1157 relay_file_read_consume(buf, read_start, ret);
1158 *ppos = relay_file_read_end_pos(buf, read_start, ret);
1159 }
ba2397ef 1160 } while (desc->count && ret);
f3a43f3f 1161 mutex_unlock(&filp->f_path.dentry->d_inode->i_mutex);
6dac40a7 1162
ba2397ef 1163 return desc->written;
6dac40a7
TZ
1164}
1165
1166static ssize_t relay_file_read(struct file *filp,
1167 char __user *buffer,
1168 size_t count,
1169 loff_t *ppos)
1170{
ba2397ef
AV
1171 read_descriptor_t desc;
1172 desc.written = 0;
1173 desc.count = count;
1174 desc.arg.buf = buffer;
1175 desc.error = 0;
1176 return relay_file_read_subbufs(filp, ppos, subbuf_read_actor,
1177 NULL, &desc);
6dac40a7
TZ
1178}
1179
1db60cf2
JA
1180static void relay_consume_bytes(struct rchan_buf *rbuf, int bytes_consumed)
1181{
1182 rbuf->bytes_consumed += bytes_consumed;
1183
1184 if (rbuf->bytes_consumed >= rbuf->chan->subbuf_size) {
1185 relay_subbufs_consumed(rbuf->chan, rbuf->cpu, 1);
1186 rbuf->bytes_consumed %= rbuf->chan->subbuf_size;
1187 }
1188}
1189
ebf99093
TZ
1190static void relay_pipe_buf_release(struct pipe_inode_info *pipe,
1191 struct pipe_buffer *buf)
6dac40a7 1192{
ebf99093
TZ
1193 struct rchan_buf *rbuf;
1194
1195 rbuf = (struct rchan_buf *)page_private(buf->page);
1db60cf2 1196 relay_consume_bytes(rbuf, buf->private);
ebf99093
TZ
1197}
1198
1199static struct pipe_buf_operations relay_pipe_buf_ops = {
1200 .can_merge = 0,
1201 .map = generic_pipe_buf_map,
1202 .unmap = generic_pipe_buf_unmap,
cac36bb0 1203 .confirm = generic_pipe_buf_confirm,
ebf99093
TZ
1204 .release = relay_pipe_buf_release,
1205 .steal = generic_pipe_buf_steal,
1206 .get = generic_pipe_buf_get,
1207};
1208
5eb7f9fa
JA
1209static void relay_page_release(struct splice_pipe_desc *spd, unsigned int i)
1210{
1211}
1212
d3f35d98 1213/*
ebf99093
TZ
1214 * subbuf_splice_actor - splice up to one subbuf's worth of data
1215 */
1216static int subbuf_splice_actor(struct file *in,
1217 loff_t *ppos,
1218 struct pipe_inode_info *pipe,
1219 size_t len,
1220 unsigned int flags,
1221 int *nonpad_ret)
1222{
16d54669 1223 unsigned int pidx, poff, total_len, subbuf_pages, nr_pages, ret;
ebf99093
TZ
1224 struct rchan_buf *rbuf = in->private_data;
1225 unsigned int subbuf_size = rbuf->chan->subbuf_size;
24da24de
TZ
1226 uint64_t pos = (uint64_t) *ppos;
1227 uint32_t alloc_size = (uint32_t) rbuf->chan->alloc_size;
1228 size_t read_start = (size_t) do_div(pos, alloc_size);
ebf99093
TZ
1229 size_t read_subbuf = read_start / subbuf_size;
1230 size_t padding = rbuf->padding[read_subbuf];
1231 size_t nonpad_end = read_subbuf * subbuf_size + subbuf_size - padding;
1db60cf2
JA
1232 struct page *pages[PIPE_BUFFERS];
1233 struct partial_page partial[PIPE_BUFFERS];
1234 struct splice_pipe_desc spd = {
1235 .pages = pages,
1236 .nr_pages = 0,
1237 .partial = partial,
1238 .flags = flags,
1239 .ops = &relay_pipe_buf_ops,
5eb7f9fa 1240 .spd_release = relay_page_release,
1db60cf2 1241 };
ebf99093
TZ
1242
1243 if (rbuf->subbufs_produced == rbuf->subbufs_consumed)
1244 return 0;
1245
1db60cf2
JA
1246 /*
1247 * Adjust read len, if longer than what is available
1248 */
1249 if (len > (subbuf_size - read_start % subbuf_size))
1250 len = subbuf_size - read_start % subbuf_size;
ebf99093
TZ
1251
1252 subbuf_pages = rbuf->chan->alloc_size >> PAGE_SHIFT;
1253 pidx = (read_start / PAGE_SIZE) % subbuf_pages;
1254 poff = read_start & ~PAGE_MASK;
16d54669 1255 nr_pages = min_t(unsigned int, subbuf_pages, PIPE_BUFFERS);
ebf99093 1256
16d54669 1257 for (total_len = 0; spd.nr_pages < nr_pages; spd.nr_pages++) {
1db60cf2
JA
1258 unsigned int this_len, this_end, private;
1259 unsigned int cur_pos = read_start + total_len;
ebf99093 1260
1db60cf2 1261 if (!len)
ebf99093 1262 break;
ebf99093 1263
1db60cf2
JA
1264 this_len = min_t(unsigned long, len, PAGE_SIZE - poff);
1265 private = this_len;
ebf99093 1266
1db60cf2
JA
1267 spd.pages[spd.nr_pages] = rbuf->page_array[pidx];
1268 spd.partial[spd.nr_pages].offset = poff;
ebf99093 1269
1db60cf2
JA
1270 this_end = cur_pos + this_len;
1271 if (this_end >= nonpad_end) {
1272 this_len = nonpad_end - cur_pos;
1273 private = this_len + padding;
ebf99093 1274 }
1db60cf2
JA
1275 spd.partial[spd.nr_pages].len = this_len;
1276 spd.partial[spd.nr_pages].private = private;
ebf99093 1277
1db60cf2
JA
1278 len -= this_len;
1279 total_len += this_len;
1280 poff = 0;
1281 pidx = (pidx + 1) % subbuf_pages;
ebf99093 1282
1db60cf2
JA
1283 if (this_end >= nonpad_end) {
1284 spd.nr_pages++;
ebf99093
TZ
1285 break;
1286 }
ebf99093
TZ
1287 }
1288
1db60cf2
JA
1289 if (!spd.nr_pages)
1290 return 0;
ebf99093 1291
1db60cf2
JA
1292 ret = *nonpad_ret = splice_to_pipe(pipe, &spd);
1293 if (ret < 0 || ret < total_len)
1294 return ret;
ebf99093 1295
1db60cf2
JA
1296 if (read_start + ret == nonpad_end)
1297 ret += padding;
1298
1299 return ret;
ebf99093
TZ
1300}
1301
1302static ssize_t relay_file_splice_read(struct file *in,
1303 loff_t *ppos,
1304 struct pipe_inode_info *pipe,
1305 size_t len,
1306 unsigned int flags)
1307{
1308 ssize_t spliced;
1309 int ret;
1310 int nonpad_ret = 0;
1311
1312 ret = 0;
1313 spliced = 0;
1314
a82c53a0 1315 while (len && !spliced) {
ebf99093
TZ
1316 ret = subbuf_splice_actor(in, ppos, pipe, len, flags, &nonpad_ret);
1317 if (ret < 0)
1318 break;
1319 else if (!ret) {
fbb5b7ae 1320 if (flags & SPLICE_F_NONBLOCK)
ebf99093 1321 ret = -EAGAIN;
fbb5b7ae 1322 break;
ebf99093
TZ
1323 }
1324
1325 *ppos += ret;
1326 if (ret > len)
1327 len = 0;
1328 else
1329 len -= ret;
1330 spliced += nonpad_ret;
1331 nonpad_ret = 0;
1332 }
1333
1334 if (spliced)
1335 return spliced;
1336
1337 return ret;
221415d7
JA
1338}
1339
15ad7cdc 1340const struct file_operations relay_file_operations = {
b86ff981
JA
1341 .open = relay_file_open,
1342 .poll = relay_file_poll,
1343 .mmap = relay_file_mmap,
1344 .read = relay_file_read,
1345 .llseek = no_llseek,
1346 .release = relay_file_release,
ebf99093 1347 .splice_read = relay_file_splice_read,
b86ff981
JA
1348};
1349EXPORT_SYMBOL_GPL(relay_file_operations);
23c88752
MD
1350
1351static __init int relay_init(void)
1352{
1353
1354 hotcpu_notifier(relay_hotcpu_callback, 0);
1355 return 0;
1356}
1357
20d8b67c 1358early_initcall(relay_init);