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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
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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>
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 */
27static DEFINE_MUTEX(relay_channels_mutex);
28static LIST_HEAD(relay_channels);
b86ff981
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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 */
11bac800 42static int 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 63static const struct vm_operations_struct relay_file_mmap_ops = {
a1e09612 64 .fault = relay_buf_fault,
b86ff981
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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{
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 */
82static void relay_free_page_array(struct page **array)
83{
200f1ce3 84 kvfree(array);
68ab3d88
MH
85}
86
b86ff981
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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 96static 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;
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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 123static 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);
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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
149depopulate:
150 for (j = 0; j < i; j++)
151 __free_page(buf->page_array[j]);
68ab3d88 152 relay_free_page_array(buf->page_array);
b86ff981
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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 162static 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
184free_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
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193 *
194 * Should only be called from kref_put().
195 */
01c55ed3 196static void relay_destroy_channel(struct kref *kref)
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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 206static 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
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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 231static void relay_remove_buf(struct kref *kref)
b86ff981
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232{
233 struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref);
b86ff981
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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 243static int relay_buf_empty(struct rchan_buf *buf)
b86ff981
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244{
245 return (buf->subbufs_produced - buf->subbufs_consumed) ? 0 : 1;
246}
b86ff981
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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 */
254int 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}
259EXPORT_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 */
273static 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 */
287static 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 */
295static 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 */
303static struct dentry *create_buf_file_default_callback(const char *filename,
304 struct dentry *parent,
f4ae40a6 305 umode_t mode,
b86ff981
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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 */
315static int remove_buf_file_default_callback(struct dentry *dentry)
316{
317 return -EINVAL;
318}
319
320/* relay channel default callbacks */
321static 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
26b5679e 331 * @work: contains the channel buffer
b86ff981 332 *
26b5679e 333 * This is the function used to defer reader waking
b86ff981 334 */
26b5679e 335static void wakeup_readers(struct irq_work *work)
b86ff981 336{
26b5679e
PZ
337 struct rchan_buf *buf;
338
339 buf = container_of(work, struct rchan_buf, wakeup_work);
b86ff981
JA
340 wake_up_interruptible(&buf->read_wait);
341}
342
343/**
344 * __relay_reset - reset a channel buffer
345 * @buf: the channel buffer
346 * @init: 1 if this is a first-time initialization
347 *
72fd4a35 348 * See relay_reset() for description of effect.
b86ff981 349 */
192636ad 350static void __relay_reset(struct rchan_buf *buf, unsigned int init)
b86ff981
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351{
352 size_t i;
353
354 if (init) {
355 init_waitqueue_head(&buf->read_wait);
356 kref_init(&buf->kref);
26b5679e
PZ
357 init_irq_work(&buf->wakeup_work, wakeup_readers);
358 } else {
359 irq_work_sync(&buf->wakeup_work);
360 }
b86ff981
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361
362 buf->subbufs_produced = 0;
363 buf->subbufs_consumed = 0;
364 buf->bytes_consumed = 0;
365 buf->finalized = 0;
366 buf->data = buf->start;
367 buf->offset = 0;
368
369 for (i = 0; i < buf->chan->n_subbufs; i++)
370 buf->padding[i] = 0;
371
372 buf->chan->cb->subbuf_start(buf, buf->data, NULL, 0);
373}
374
375/**
376 * relay_reset - reset the channel
377 * @chan: the channel
378 *
379 * This has the effect of erasing all data from all channel buffers
380 * and restarting the channel in its initial state. The buffers
381 * are not freed, so any mappings are still in effect.
382 *
72fd4a35 383 * NOTE. Care should be taken that the channel isn't actually
b86ff981
JA
384 * being used by anything when this call is made.
385 */
386void relay_reset(struct rchan *chan)
387{
017c59c0 388 struct rchan_buf *buf;
b86ff981 389 unsigned int i;
b86ff981
JA
390
391 if (!chan)
392 return;
393
017c59c0
AG
394 if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0))) {
395 __relay_reset(buf, 0);
23c88752 396 return;
b86ff981 397 }
23c88752
MD
398
399 mutex_lock(&relay_channels_mutex);
98ba4031 400 for_each_possible_cpu(i)
017c59c0
AG
401 if ((buf = *per_cpu_ptr(chan->buf, i)))
402 __relay_reset(buf, 0);
23c88752 403 mutex_unlock(&relay_channels_mutex);
b86ff981
JA
404}
405EXPORT_SYMBOL_GPL(relay_reset);
406
20d8b67c
EGM
407static inline void relay_set_buf_dentry(struct rchan_buf *buf,
408 struct dentry *dentry)
409{
410 buf->dentry = dentry;
7682c918 411 d_inode(buf->dentry)->i_size = buf->early_bytes;
20d8b67c
EGM
412}
413
414static struct dentry *relay_create_buf_file(struct rchan *chan,
415 struct rchan_buf *buf,
416 unsigned int cpu)
417{
418 struct dentry *dentry;
419 char *tmpname;
420
421 tmpname = kzalloc(NAME_MAX + 1, GFP_KERNEL);
422 if (!tmpname)
423 return NULL;
424 snprintf(tmpname, NAME_MAX, "%s%d", chan->base_filename, cpu);
425
426 /* Create file in fs */
427 dentry = chan->cb->create_buf_file(tmpname, chan->parent,
428 S_IRUSR, buf,
429 &chan->is_global);
430
431 kfree(tmpname);
432
433 return dentry;
434}
435
4c78a663 436/*
b86ff981
JA
437 * relay_open_buf - create a new relay channel buffer
438 *
23c88752 439 * used by relay_open() and CPU hotplug.
b86ff981 440 */
23c88752 441static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu)
b86ff981 442{
23c88752 443 struct rchan_buf *buf = NULL;
b86ff981
JA
444 struct dentry *dentry;
445
23c88752 446 if (chan->is_global)
017c59c0 447 return *per_cpu_ptr(chan->buf, 0);
b86ff981
JA
448
449 buf = relay_create_buf(chan);
450 if (!buf)
20d8b67c
EGM
451 return NULL;
452
453 if (chan->has_base_filename) {
454 dentry = relay_create_buf_file(chan, buf, cpu);
455 if (!dentry)
456 goto free_buf;
457 relay_set_buf_dentry(buf, dentry);
59dbb2a0
AG
458 } else {
459 /* Only retrieve global info, nothing more, nothing less */
460 dentry = chan->cb->create_buf_file(NULL, NULL,
461 S_IRUSR, buf,
462 &chan->is_global);
463 if (WARN_ON(dentry))
464 goto free_buf;
20d8b67c 465 }
23c88752
MD
466
467 buf->cpu = cpu;
468 __relay_reset(buf, 1);
b86ff981 469
23c88752 470 if(chan->is_global) {
017c59c0 471 *per_cpu_ptr(chan->buf, 0) = buf;
23c88752
MD
472 buf->cpu = 0;
473 }
474
20d8b67c 475 return buf;
23c88752
MD
476
477free_buf:
478 relay_destroy_buf(buf);
20d8b67c 479 return NULL;
b86ff981
JA
480}
481
482/**
483 * relay_close_buf - close a channel buffer
484 * @buf: channel buffer
485 *
486 * Marks the buffer finalized and restores the default callbacks.
487 * The channel buffer and channel buffer data structure are then freed
488 * automatically when the last reference is given up.
489 */
192636ad 490static void relay_close_buf(struct rchan_buf *buf)
b86ff981
JA
491{
492 buf->finalized = 1;
26b5679e 493 irq_work_sync(&buf->wakeup_work);
b8d4a5bf 494 buf->chan->cb->remove_buf_file(buf->dentry);
b86ff981
JA
495 kref_put(&buf->kref, relay_remove_buf);
496}
497
192636ad 498static void setup_callbacks(struct rchan *chan,
b86ff981
JA
499 struct rchan_callbacks *cb)
500{
501 if (!cb) {
502 chan->cb = &default_channel_callbacks;
503 return;
504 }
505
506 if (!cb->subbuf_start)
507 cb->subbuf_start = subbuf_start_default_callback;
508 if (!cb->buf_mapped)
509 cb->buf_mapped = buf_mapped_default_callback;
510 if (!cb->buf_unmapped)
511 cb->buf_unmapped = buf_unmapped_default_callback;
512 if (!cb->create_buf_file)
513 cb->create_buf_file = create_buf_file_default_callback;
514 if (!cb->remove_buf_file)
515 cb->remove_buf_file = remove_buf_file_default_callback;
516 chan->cb = cb;
517}
518
e6d4989a 519int relay_prepare_cpu(unsigned int cpu)
23c88752 520{
23c88752 521 struct rchan *chan;
017c59c0 522 struct rchan_buf *buf;
23c88752 523
e6d4989a
RW
524 mutex_lock(&relay_channels_mutex);
525 list_for_each_entry(chan, &relay_channels, list) {
526 if ((buf = *per_cpu_ptr(chan->buf, cpu)))
527 continue;
528 buf = relay_open_buf(chan, cpu);
529 if (!buf) {
530 pr_err("relay: cpu %d buffer creation failed\n", cpu);
531 mutex_unlock(&relay_channels_mutex);
532 return -ENOMEM;
23c88752 533 }
e6d4989a 534 *per_cpu_ptr(chan->buf, cpu) = buf;
23c88752 535 }
e6d4989a
RW
536 mutex_unlock(&relay_channels_mutex);
537 return 0;
23c88752
MD
538}
539
b86ff981
JA
540/**
541 * relay_open - create a new relay channel
20d8b67c
EGM
542 * @base_filename: base name of files to create, %NULL for buffering only
543 * @parent: dentry of parent directory, %NULL for root directory or buffer
b86ff981
JA
544 * @subbuf_size: size of sub-buffers
545 * @n_subbufs: number of sub-buffers
546 * @cb: client callback functions
23c88752 547 * @private_data: user-defined data
b86ff981 548 *
4c78a663 549 * Returns channel pointer if successful, %NULL otherwise.
b86ff981
JA
550 *
551 * Creates a channel buffer for each cpu using the sizes and
552 * attributes specified. The created channel buffer files
553 * will be named base_filename0...base_filenameN-1. File
72fd4a35 554 * permissions will be %S_IRUSR.
59dbb2a0
AG
555 *
556 * If opening a buffer (@parent = NULL) that you later wish to register
557 * in a filesystem, call relay_late_setup_files() once the @parent dentry
558 * is available.
b86ff981
JA
559 */
560struct rchan *relay_open(const char *base_filename,
561 struct dentry *parent,
562 size_t subbuf_size,
563 size_t n_subbufs,
23c88752
MD
564 struct rchan_callbacks *cb,
565 void *private_data)
b86ff981
JA
566{
567 unsigned int i;
568 struct rchan *chan;
017c59c0 569 struct rchan_buf *buf;
b86ff981
JA
570
571 if (!(subbuf_size && n_subbufs))
572 return NULL;
f6302f1b
DC
573 if (subbuf_size > UINT_MAX / n_subbufs)
574 return NULL;
b86ff981 575
cd861280 576 chan = kzalloc(sizeof(struct rchan), GFP_KERNEL);
b86ff981
JA
577 if (!chan)
578 return NULL;
579
017c59c0 580 chan->buf = alloc_percpu(struct rchan_buf *);
b86ff981
JA
581 chan->version = RELAYFS_CHANNEL_VERSION;
582 chan->n_subbufs = n_subbufs;
583 chan->subbuf_size = subbuf_size;
a05342cb 584 chan->alloc_size = PAGE_ALIGN(subbuf_size * n_subbufs);
23c88752
MD
585 chan->parent = parent;
586 chan->private_data = private_data;
20d8b67c
EGM
587 if (base_filename) {
588 chan->has_base_filename = 1;
589 strlcpy(chan->base_filename, base_filename, NAME_MAX);
590 }
b86ff981
JA
591 setup_callbacks(chan, cb);
592 kref_init(&chan->kref);
593
23c88752 594 mutex_lock(&relay_channels_mutex);
b86ff981 595 for_each_online_cpu(i) {
017c59c0
AG
596 buf = relay_open_buf(chan, i);
597 if (!buf)
b86ff981 598 goto free_bufs;
017c59c0 599 *per_cpu_ptr(chan->buf, i) = buf;
b86ff981 600 }
23c88752
MD
601 list_add(&chan->list, &relay_channels);
602 mutex_unlock(&relay_channels_mutex);
b86ff981 603
b86ff981
JA
604 return chan;
605
606free_bufs:
98ba4031 607 for_each_possible_cpu(i) {
017c59c0
AG
608 if ((buf = *per_cpu_ptr(chan->buf, i)))
609 relay_close_buf(buf);
b86ff981 610 }
b86ff981 611
b86ff981 612 kref_put(&chan->kref, relay_destroy_channel);
23c88752 613 mutex_unlock(&relay_channels_mutex);
ba62bafe 614 kfree(chan);
b86ff981
JA
615 return NULL;
616}
617EXPORT_SYMBOL_GPL(relay_open);
618
20d8b67c
EGM
619struct rchan_percpu_buf_dispatcher {
620 struct rchan_buf *buf;
621 struct dentry *dentry;
622};
623
624/* Called in atomic context. */
625static void __relay_set_buf_dentry(void *info)
626{
627 struct rchan_percpu_buf_dispatcher *p = info;
628
629 relay_set_buf_dentry(p->buf, p->dentry);
630}
631
632/**
633 * relay_late_setup_files - triggers file creation
634 * @chan: channel to operate on
635 * @base_filename: base name of files to create
636 * @parent: dentry of parent directory, %NULL for root directory
637 *
638 * Returns 0 if successful, non-zero otherwise.
639 *
59dbb2a0
AG
640 * Use to setup files for a previously buffer-only channel created
641 * by relay_open() with a NULL parent dentry.
642 *
643 * For example, this is useful for perfomring early tracing in kernel,
644 * before VFS is up and then exposing the early results once the dentry
645 * is available.
20d8b67c
EGM
646 */
647int relay_late_setup_files(struct rchan *chan,
648 const char *base_filename,
649 struct dentry *parent)
650{
651 int err = 0;
652 unsigned int i, curr_cpu;
653 unsigned long flags;
654 struct dentry *dentry;
017c59c0 655 struct rchan_buf *buf;
20d8b67c
EGM
656 struct rchan_percpu_buf_dispatcher disp;
657
658 if (!chan || !base_filename)
659 return -EINVAL;
660
661 strlcpy(chan->base_filename, base_filename, NAME_MAX);
662
663 mutex_lock(&relay_channels_mutex);
664 /* Is chan already set up? */
b786c6a9
JS
665 if (unlikely(chan->has_base_filename)) {
666 mutex_unlock(&relay_channels_mutex);
20d8b67c 667 return -EEXIST;
b786c6a9 668 }
20d8b67c
EGM
669 chan->has_base_filename = 1;
670 chan->parent = parent;
59dbb2a0
AG
671
672 if (chan->is_global) {
673 err = -EINVAL;
017c59c0
AG
674 buf = *per_cpu_ptr(chan->buf, 0);
675 if (!WARN_ON_ONCE(!buf)) {
676 dentry = relay_create_buf_file(chan, buf, 0);
59dbb2a0 677 if (dentry && !WARN_ON_ONCE(!chan->is_global)) {
017c59c0 678 relay_set_buf_dentry(buf, dentry);
59dbb2a0
AG
679 err = 0;
680 }
681 }
682 mutex_unlock(&relay_channels_mutex);
683 return err;
684 }
685
20d8b67c
EGM
686 curr_cpu = get_cpu();
687 /*
688 * The CPU hotplug notifier ran before us and created buffers with
689 * no files associated. So it's safe to call relay_setup_buf_file()
690 * on all currently online CPUs.
691 */
692 for_each_online_cpu(i) {
017c59c0
AG
693 buf = *per_cpu_ptr(chan->buf, i);
694 if (unlikely(!buf)) {
7a51cffb 695 WARN_ONCE(1, KERN_ERR "CPU has no buffer!\n");
20d8b67c
EGM
696 err = -EINVAL;
697 break;
698 }
699
017c59c0 700 dentry = relay_create_buf_file(chan, buf, i);
20d8b67c
EGM
701 if (unlikely(!dentry)) {
702 err = -EINVAL;
703 break;
704 }
705
706 if (curr_cpu == i) {
707 local_irq_save(flags);
017c59c0 708 relay_set_buf_dentry(buf, dentry);
20d8b67c
EGM
709 local_irq_restore(flags);
710 } else {
017c59c0 711 disp.buf = buf;
20d8b67c
EGM
712 disp.dentry = dentry;
713 smp_mb();
714 /* relay_channels_mutex must be held, so wait. */
715 err = smp_call_function_single(i,
716 __relay_set_buf_dentry,
717 &disp, 1);
718 }
719 if (unlikely(err))
720 break;
721 }
722 put_cpu();
723 mutex_unlock(&relay_channels_mutex);
724
725 return err;
726}
59dbb2a0 727EXPORT_SYMBOL_GPL(relay_late_setup_files);
20d8b67c 728
b86ff981
JA
729/**
730 * relay_switch_subbuf - switch to a new sub-buffer
731 * @buf: channel buffer
732 * @length: size of current event
733 *
734 * Returns either the length passed in or 0 if full.
735 *
736 * Performs sub-buffer-switch tasks such as invoking callbacks,
737 * updating padding counts, waking up readers, etc.
738 */
739size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length)
740{
741 void *old, *new;
742 size_t old_subbuf, new_subbuf;
743
744 if (unlikely(length > buf->chan->subbuf_size))
745 goto toobig;
746
747 if (buf->offset != buf->chan->subbuf_size + 1) {
748 buf->prev_padding = buf->chan->subbuf_size - buf->offset;
749 old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs;
750 buf->padding[old_subbuf] = buf->prev_padding;
751 buf->subbufs_produced++;
20d8b67c 752 if (buf->dentry)
7682c918 753 d_inode(buf->dentry)->i_size +=
20d8b67c
EGM
754 buf->chan->subbuf_size -
755 buf->padding[old_subbuf];
756 else
757 buf->early_bytes += buf->chan->subbuf_size -
758 buf->padding[old_subbuf];
221415d7 759 smp_mb();
26b5679e 760 if (waitqueue_active(&buf->read_wait)) {
7c9cb383
TZ
761 /*
762 * Calling wake_up_interruptible() from here
763 * will deadlock if we happen to be logging
764 * from the scheduler (trying to re-grab
765 * rq->lock), so defer it.
766 */
26b5679e
PZ
767 irq_work_queue(&buf->wakeup_work);
768 }
b86ff981
JA
769 }
770
771 old = buf->data;
772 new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs;
773 new = buf->start + new_subbuf * buf->chan->subbuf_size;
774 buf->offset = 0;
775 if (!buf->chan->cb->subbuf_start(buf, new, old, buf->prev_padding)) {
776 buf->offset = buf->chan->subbuf_size + 1;
777 return 0;
778 }
779 buf->data = new;
780 buf->padding[new_subbuf] = 0;
781
782 if (unlikely(length + buf->offset > buf->chan->subbuf_size))
783 goto toobig;
784
785 return length;
786
787toobig:
788 buf->chan->last_toobig = length;
789 return 0;
790}
791EXPORT_SYMBOL_GPL(relay_switch_subbuf);
792
793/**
794 * relay_subbufs_consumed - update the buffer's sub-buffers-consumed count
795 * @chan: the channel
796 * @cpu: the cpu associated with the channel buffer to update
797 * @subbufs_consumed: number of sub-buffers to add to current buf's count
798 *
799 * Adds to the channel buffer's consumed sub-buffer count.
800 * subbufs_consumed should be the number of sub-buffers newly consumed,
801 * not the total consumed.
802 *
72fd4a35 803 * NOTE. Kernel clients don't need to call this function if the channel
b86ff981
JA
804 * mode is 'overwrite'.
805 */
806void relay_subbufs_consumed(struct rchan *chan,
807 unsigned int cpu,
808 size_t subbufs_consumed)
809{
810 struct rchan_buf *buf;
811
9a29d0fb 812 if (!chan || cpu >= NR_CPUS)
b86ff981
JA
813 return;
814
017c59c0 815 buf = *per_cpu_ptr(chan->buf, cpu);
9a29d0fb 816 if (!buf || subbufs_consumed > chan->n_subbufs)
b86ff981
JA
817 return;
818
2c53d910 819 if (subbufs_consumed > buf->subbufs_produced - buf->subbufs_consumed)
b86ff981 820 buf->subbufs_consumed = buf->subbufs_produced;
2c53d910
AS
821 else
822 buf->subbufs_consumed += subbufs_consumed;
b86ff981
JA
823}
824EXPORT_SYMBOL_GPL(relay_subbufs_consumed);
825
826/**
827 * relay_close - close the channel
828 * @chan: the channel
829 *
830 * Closes all channel buffers and frees the channel.
831 */
832void relay_close(struct rchan *chan)
833{
017c59c0 834 struct rchan_buf *buf;
b86ff981 835 unsigned int i;
b86ff981
JA
836
837 if (!chan)
838 return;
839
23c88752 840 mutex_lock(&relay_channels_mutex);
017c59c0
AG
841 if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0)))
842 relay_close_buf(buf);
23c88752
MD
843 else
844 for_each_possible_cpu(i)
017c59c0
AG
845 if ((buf = *per_cpu_ptr(chan->buf, i)))
846 relay_close_buf(buf);
b86ff981
JA
847
848 if (chan->last_toobig)
849 printk(KERN_WARNING "relay: one or more items not logged "
5b5e0928 850 "[item size (%zd) > sub-buffer size (%zd)]\n",
b86ff981
JA
851 chan->last_toobig, chan->subbuf_size);
852
23c88752 853 list_del(&chan->list);
b86ff981 854 kref_put(&chan->kref, relay_destroy_channel);
23c88752 855 mutex_unlock(&relay_channels_mutex);
b86ff981
JA
856}
857EXPORT_SYMBOL_GPL(relay_close);
858
859/**
860 * relay_flush - close the channel
861 * @chan: the channel
862 *
4c78a663 863 * Flushes all channel buffers, i.e. forces buffer switch.
b86ff981
JA
864 */
865void relay_flush(struct rchan *chan)
866{
017c59c0 867 struct rchan_buf *buf;
b86ff981 868 unsigned int i;
b86ff981
JA
869
870 if (!chan)
871 return;
872
017c59c0
AG
873 if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0))) {
874 relay_switch_subbuf(buf, 0);
23c88752 875 return;
b86ff981 876 }
23c88752
MD
877
878 mutex_lock(&relay_channels_mutex);
879 for_each_possible_cpu(i)
017c59c0
AG
880 if ((buf = *per_cpu_ptr(chan->buf, i)))
881 relay_switch_subbuf(buf, 0);
23c88752 882 mutex_unlock(&relay_channels_mutex);
b86ff981
JA
883}
884EXPORT_SYMBOL_GPL(relay_flush);
885
886/**
887 * relay_file_open - open file op for relay files
888 * @inode: the inode
889 * @filp: the file
890 *
891 * Increments the channel buffer refcount.
892 */
893static int relay_file_open(struct inode *inode, struct file *filp)
894{
8e18e294 895 struct rchan_buf *buf = inode->i_private;
b86ff981
JA
896 kref_get(&buf->kref);
897 filp->private_data = buf;
898
37529fe9 899 return nonseekable_open(inode, filp);
b86ff981
JA
900}
901
902/**
903 * relay_file_mmap - mmap file op for relay files
904 * @filp: the file
905 * @vma: the vma describing what to map
906 *
72fd4a35 907 * Calls upon relay_mmap_buf() to map the file into user space.
b86ff981
JA
908 */
909static int relay_file_mmap(struct file *filp, struct vm_area_struct *vma)
910{
911 struct rchan_buf *buf = filp->private_data;
912 return relay_mmap_buf(buf, vma);
913}
914
915/**
916 * relay_file_poll - poll file op for relay files
917 * @filp: the file
918 * @wait: poll table
919 *
920 * Poll implemention.
921 */
922static unsigned int relay_file_poll(struct file *filp, poll_table *wait)
923{
924 unsigned int mask = 0;
925 struct rchan_buf *buf = filp->private_data;
926
927 if (buf->finalized)
928 return POLLERR;
929
930 if (filp->f_mode & FMODE_READ) {
931 poll_wait(filp, &buf->read_wait, wait);
932 if (!relay_buf_empty(buf))
933 mask |= POLLIN | POLLRDNORM;
934 }
935
936 return mask;
937}
938
939/**
940 * relay_file_release - release file op for relay files
941 * @inode: the inode
942 * @filp: the file
943 *
944 * Decrements the channel refcount, as the filesystem is
945 * no longer using it.
946 */
947static int relay_file_release(struct inode *inode, struct file *filp)
948{
949 struct rchan_buf *buf = filp->private_data;
950 kref_put(&buf->kref, relay_remove_buf);
951
952 return 0;
953}
954
4c78a663 955/*
b86ff981
JA
956 * relay_file_read_consume - update the consumed count for the buffer
957 */
958static void relay_file_read_consume(struct rchan_buf *buf,
959 size_t read_pos,
960 size_t bytes_consumed)
961{
962 size_t subbuf_size = buf->chan->subbuf_size;
963 size_t n_subbufs = buf->chan->n_subbufs;
964 size_t read_subbuf;
965
32194450
TZ
966 if (buf->subbufs_produced == buf->subbufs_consumed &&
967 buf->offset == buf->bytes_consumed)
968 return;
969
b86ff981
JA
970 if (buf->bytes_consumed + bytes_consumed > subbuf_size) {
971 relay_subbufs_consumed(buf->chan, buf->cpu, 1);
972 buf->bytes_consumed = 0;
973 }
974
975 buf->bytes_consumed += bytes_consumed;
a66e356c
MH
976 if (!read_pos)
977 read_subbuf = buf->subbufs_consumed % n_subbufs;
978 else
979 read_subbuf = read_pos / buf->chan->subbuf_size;
b86ff981
JA
980 if (buf->bytes_consumed + buf->padding[read_subbuf] == subbuf_size) {
981 if ((read_subbuf == buf->subbufs_produced % n_subbufs) &&
982 (buf->offset == subbuf_size))
983 return;
984 relay_subbufs_consumed(buf->chan, buf->cpu, 1);
985 buf->bytes_consumed = 0;
986 }
987}
988
4c78a663 989/*
b86ff981
JA
990 * relay_file_read_avail - boolean, are there unconsumed bytes available?
991 */
992static int relay_file_read_avail(struct rchan_buf *buf, size_t read_pos)
993{
b86ff981
JA
994 size_t subbuf_size = buf->chan->subbuf_size;
995 size_t n_subbufs = buf->chan->n_subbufs;
221415d7
JA
996 size_t produced = buf->subbufs_produced;
997 size_t consumed = buf->subbufs_consumed;
b86ff981 998
221415d7 999 relay_file_read_consume(buf, read_pos, 0);
b86ff981 1000
32194450
TZ
1001 consumed = buf->subbufs_consumed;
1002
221415d7
JA
1003 if (unlikely(buf->offset > subbuf_size)) {
1004 if (produced == consumed)
1005 return 0;
1006 return 1;
b86ff981
JA
1007 }
1008
221415d7 1009 if (unlikely(produced - consumed >= n_subbufs)) {
a66e356c 1010 consumed = produced - n_subbufs + 1;
221415d7 1011 buf->subbufs_consumed = consumed;
a66e356c 1012 buf->bytes_consumed = 0;
221415d7 1013 }
1bfbc608 1014
221415d7
JA
1015 produced = (produced % n_subbufs) * subbuf_size + buf->offset;
1016 consumed = (consumed % n_subbufs) * subbuf_size + buf->bytes_consumed;
1017
1018 if (consumed > produced)
1019 produced += n_subbufs * subbuf_size;
1bfbc608 1020
32194450
TZ
1021 if (consumed == produced) {
1022 if (buf->offset == subbuf_size &&
1023 buf->subbufs_produced > buf->subbufs_consumed)
1024 return 1;
b86ff981 1025 return 0;
32194450 1026 }
b86ff981 1027
b86ff981
JA
1028 return 1;
1029}
1030
1031/**
1032 * relay_file_read_subbuf_avail - return bytes available in sub-buffer
4c78a663
RD
1033 * @read_pos: file read position
1034 * @buf: relay channel buffer
b86ff981
JA
1035 */
1036static size_t relay_file_read_subbuf_avail(size_t read_pos,
1037 struct rchan_buf *buf)
1038{
1039 size_t padding, avail = 0;
1040 size_t read_subbuf, read_offset, write_subbuf, write_offset;
1041 size_t subbuf_size = buf->chan->subbuf_size;
1042
1043 write_subbuf = (buf->data - buf->start) / subbuf_size;
1044 write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset;
1045 read_subbuf = read_pos / subbuf_size;
1046 read_offset = read_pos % subbuf_size;
1047 padding = buf->padding[read_subbuf];
1048
1049 if (read_subbuf == write_subbuf) {
1050 if (read_offset + padding < write_offset)
1051 avail = write_offset - (read_offset + padding);
1052 } else
1053 avail = (subbuf_size - padding) - read_offset;
1054
1055 return avail;
1056}
1057
1058/**
1059 * relay_file_read_start_pos - find the first available byte to read
4c78a663
RD
1060 * @read_pos: file read position
1061 * @buf: relay channel buffer
b86ff981 1062 *
72fd4a35 1063 * If the @read_pos is in the middle of padding, return the
b86ff981
JA
1064 * position of the first actually available byte, otherwise
1065 * return the original value.
1066 */
1067static size_t relay_file_read_start_pos(size_t read_pos,
1068 struct rchan_buf *buf)
1069{
1070 size_t read_subbuf, padding, padding_start, padding_end;
1071 size_t subbuf_size = buf->chan->subbuf_size;
1072 size_t n_subbufs = buf->chan->n_subbufs;
8d62fdeb 1073 size_t consumed = buf->subbufs_consumed % n_subbufs;
b86ff981 1074
8d62fdeb
DW
1075 if (!read_pos)
1076 read_pos = consumed * subbuf_size + buf->bytes_consumed;
b86ff981
JA
1077 read_subbuf = read_pos / subbuf_size;
1078 padding = buf->padding[read_subbuf];
1079 padding_start = (read_subbuf + 1) * subbuf_size - padding;
1080 padding_end = (read_subbuf + 1) * subbuf_size;
1081 if (read_pos >= padding_start && read_pos < padding_end) {
1082 read_subbuf = (read_subbuf + 1) % n_subbufs;
1083 read_pos = read_subbuf * subbuf_size;
1084 }
1085
1086 return read_pos;
1087}
1088
1089/**
1090 * relay_file_read_end_pos - return the new read position
4c78a663
RD
1091 * @read_pos: file read position
1092 * @buf: relay channel buffer
1093 * @count: number of bytes to be read
b86ff981
JA
1094 */
1095static size_t relay_file_read_end_pos(struct rchan_buf *buf,
1096 size_t read_pos,
1097 size_t count)
1098{
1099 size_t read_subbuf, padding, end_pos;
1100 size_t subbuf_size = buf->chan->subbuf_size;
1101 size_t n_subbufs = buf->chan->n_subbufs;
1102
1103 read_subbuf = read_pos / subbuf_size;
1104 padding = buf->padding[read_subbuf];
1105 if (read_pos % subbuf_size + count + padding == subbuf_size)
1106 end_pos = (read_subbuf + 1) * subbuf_size;
1107 else
1108 end_pos = read_pos + count;
1109 if (end_pos >= subbuf_size * n_subbufs)
1110 end_pos = 0;
1111
1112 return end_pos;
1113}
1114
a7c22421
AV
1115static ssize_t relay_file_read(struct file *filp,
1116 char __user *buffer,
1117 size_t count,
1118 loff_t *ppos)
221415d7 1119{
6dac40a7
TZ
1120 struct rchan_buf *buf = filp->private_data;
1121 size_t read_start, avail;
a7c22421 1122 size_t written = 0;
6dac40a7 1123 int ret;
221415d7 1124
a7c22421 1125 if (!count)
221415d7
JA
1126 return 0;
1127
5955102c 1128 inode_lock(file_inode(filp));
221415d7 1129 do {
a7c22421
AV
1130 void *from;
1131
6dac40a7
TZ
1132 if (!relay_file_read_avail(buf, *ppos))
1133 break;
1134
1135 read_start = relay_file_read_start_pos(*ppos, buf);
1136 avail = relay_file_read_subbuf_avail(read_start, buf);
1137 if (!avail)
221415d7 1138 break;
221415d7 1139
a7c22421
AV
1140 avail = min(count, avail);
1141 from = buf->start + read_start;
1142 ret = avail;
1143 if (copy_to_user(buffer, from, avail))
6dac40a7
TZ
1144 break;
1145
a7c22421
AV
1146 buffer += ret;
1147 written += ret;
1148 count -= ret;
6dac40a7 1149
a7c22421
AV
1150 relay_file_read_consume(buf, read_start, ret);
1151 *ppos = relay_file_read_end_pos(buf, read_start, ret);
1152 } while (count);
1153 inode_unlock(file_inode(filp));
6dac40a7 1154
a7c22421 1155 return written;
6dac40a7
TZ
1156}
1157
1db60cf2
JA
1158static void relay_consume_bytes(struct rchan_buf *rbuf, int bytes_consumed)
1159{
1160 rbuf->bytes_consumed += bytes_consumed;
1161
1162 if (rbuf->bytes_consumed >= rbuf->chan->subbuf_size) {
1163 relay_subbufs_consumed(rbuf->chan, rbuf->cpu, 1);
1164 rbuf->bytes_consumed %= rbuf->chan->subbuf_size;
1165 }
1166}
1167
ebf99093
TZ
1168static void relay_pipe_buf_release(struct pipe_inode_info *pipe,
1169 struct pipe_buffer *buf)
6dac40a7 1170{
ebf99093
TZ
1171 struct rchan_buf *rbuf;
1172
1173 rbuf = (struct rchan_buf *)page_private(buf->page);
1db60cf2 1174 relay_consume_bytes(rbuf, buf->private);
ebf99093
TZ
1175}
1176
28dfef8f 1177static const struct pipe_buf_operations relay_pipe_buf_ops = {
ebf99093 1178 .can_merge = 0,
cac36bb0 1179 .confirm = generic_pipe_buf_confirm,
ebf99093
TZ
1180 .release = relay_pipe_buf_release,
1181 .steal = generic_pipe_buf_steal,
1182 .get = generic_pipe_buf_get,
1183};
1184
5eb7f9fa
JA
1185static void relay_page_release(struct splice_pipe_desc *spd, unsigned int i)
1186{
1187}
1188
d3f35d98 1189/*
ebf99093
TZ
1190 * subbuf_splice_actor - splice up to one subbuf's worth of data
1191 */
5f1664f9 1192static ssize_t subbuf_splice_actor(struct file *in,
ebf99093
TZ
1193 loff_t *ppos,
1194 struct pipe_inode_info *pipe,
1195 size_t len,
1196 unsigned int flags,
1197 int *nonpad_ret)
1198{
5f1664f9 1199 unsigned int pidx, poff, total_len, subbuf_pages, nr_pages;
ebf99093
TZ
1200 struct rchan_buf *rbuf = in->private_data;
1201 unsigned int subbuf_size = rbuf->chan->subbuf_size;
24da24de
TZ
1202 uint64_t pos = (uint64_t) *ppos;
1203 uint32_t alloc_size = (uint32_t) rbuf->chan->alloc_size;
1204 size_t read_start = (size_t) do_div(pos, alloc_size);
ebf99093
TZ
1205 size_t read_subbuf = read_start / subbuf_size;
1206 size_t padding = rbuf->padding[read_subbuf];
1207 size_t nonpad_end = read_subbuf * subbuf_size + subbuf_size - padding;
35f3d14d
JA
1208 struct page *pages[PIPE_DEF_BUFFERS];
1209 struct partial_page partial[PIPE_DEF_BUFFERS];
1db60cf2
JA
1210 struct splice_pipe_desc spd = {
1211 .pages = pages,
1212 .nr_pages = 0,
047fe360 1213 .nr_pages_max = PIPE_DEF_BUFFERS,
1db60cf2 1214 .partial = partial,
1db60cf2 1215 .ops = &relay_pipe_buf_ops,
5eb7f9fa 1216 .spd_release = relay_page_release,
1db60cf2 1217 };
5f1664f9 1218 ssize_t ret;
ebf99093
TZ
1219
1220 if (rbuf->subbufs_produced == rbuf->subbufs_consumed)
1221 return 0;
35f3d14d
JA
1222 if (splice_grow_spd(pipe, &spd))
1223 return -ENOMEM;
ebf99093 1224
1db60cf2
JA
1225 /*
1226 * Adjust read len, if longer than what is available
1227 */
1228 if (len > (subbuf_size - read_start % subbuf_size))
1229 len = subbuf_size - read_start % subbuf_size;
ebf99093
TZ
1230
1231 subbuf_pages = rbuf->chan->alloc_size >> PAGE_SHIFT;
1232 pidx = (read_start / PAGE_SIZE) % subbuf_pages;
1233 poff = read_start & ~PAGE_MASK;
a786c06d 1234 nr_pages = min_t(unsigned int, subbuf_pages, spd.nr_pages_max);
ebf99093 1235
16d54669 1236 for (total_len = 0; spd.nr_pages < nr_pages; spd.nr_pages++) {
1db60cf2
JA
1237 unsigned int this_len, this_end, private;
1238 unsigned int cur_pos = read_start + total_len;
ebf99093 1239
1db60cf2 1240 if (!len)
ebf99093 1241 break;
ebf99093 1242
1db60cf2
JA
1243 this_len = min_t(unsigned long, len, PAGE_SIZE - poff);
1244 private = this_len;
ebf99093 1245
1db60cf2
JA
1246 spd.pages[spd.nr_pages] = rbuf->page_array[pidx];
1247 spd.partial[spd.nr_pages].offset = poff;
ebf99093 1248
1db60cf2
JA
1249 this_end = cur_pos + this_len;
1250 if (this_end >= nonpad_end) {
1251 this_len = nonpad_end - cur_pos;
1252 private = this_len + padding;
ebf99093 1253 }
1db60cf2
JA
1254 spd.partial[spd.nr_pages].len = this_len;
1255 spd.partial[spd.nr_pages].private = private;
ebf99093 1256
1db60cf2
JA
1257 len -= this_len;
1258 total_len += this_len;
1259 poff = 0;
1260 pidx = (pidx + 1) % subbuf_pages;
ebf99093 1261
1db60cf2
JA
1262 if (this_end >= nonpad_end) {
1263 spd.nr_pages++;
ebf99093
TZ
1264 break;
1265 }
ebf99093
TZ
1266 }
1267
35f3d14d 1268 ret = 0;
1db60cf2 1269 if (!spd.nr_pages)
35f3d14d 1270 goto out;
ebf99093 1271
1db60cf2
JA
1272 ret = *nonpad_ret = splice_to_pipe(pipe, &spd);
1273 if (ret < 0 || ret < total_len)
35f3d14d 1274 goto out;
ebf99093 1275
1db60cf2
JA
1276 if (read_start + ret == nonpad_end)
1277 ret += padding;
1278
35f3d14d 1279out:
047fe360
ED
1280 splice_shrink_spd(&spd);
1281 return ret;
ebf99093
TZ
1282}
1283
1284static ssize_t relay_file_splice_read(struct file *in,
1285 loff_t *ppos,
1286 struct pipe_inode_info *pipe,
1287 size_t len,
1288 unsigned int flags)
1289{
1290 ssize_t spliced;
1291 int ret;
1292 int nonpad_ret = 0;
1293
1294 ret = 0;
1295 spliced = 0;
1296
a82c53a0 1297 while (len && !spliced) {
ebf99093
TZ
1298 ret = subbuf_splice_actor(in, ppos, pipe, len, flags, &nonpad_ret);
1299 if (ret < 0)
1300 break;
1301 else if (!ret) {
fbb5b7ae 1302 if (flags & SPLICE_F_NONBLOCK)
ebf99093 1303 ret = -EAGAIN;
fbb5b7ae 1304 break;
ebf99093
TZ
1305 }
1306
1307 *ppos += ret;
1308 if (ret > len)
1309 len = 0;
1310 else
1311 len -= ret;
1312 spliced += nonpad_ret;
1313 nonpad_ret = 0;
1314 }
1315
1316 if (spliced)
1317 return spliced;
1318
1319 return ret;
221415d7
JA
1320}
1321
15ad7cdc 1322const struct file_operations relay_file_operations = {
b86ff981
JA
1323 .open = relay_file_open,
1324 .poll = relay_file_poll,
1325 .mmap = relay_file_mmap,
1326 .read = relay_file_read,
1327 .llseek = no_llseek,
1328 .release = relay_file_release,
ebf99093 1329 .splice_read = relay_file_splice_read,
b86ff981
JA
1330};
1331EXPORT_SYMBOL_GPL(relay_file_operations);