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