blob: 91e8fbf8aff38c5d495c52dd7e3e7b0691afe5ae
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 | static void relay_file_mmap_close(struct vm_area_struct *vma) |
34 | { |
35 | struct rchan_buf *buf = vma->vm_private_data; |
36 | buf->chan->cb->buf_unmapped(buf, vma->vm_file); |
37 | } |
38 | |
39 | /* |
40 | * fault() vm_op implementation for relay file mapping. |
41 | */ |
42 | static int relay_buf_fault(struct vm_area_struct *vma, struct vm_fault *vmf) |
43 | { |
44 | struct page *page; |
45 | struct rchan_buf *buf = vma->vm_private_data; |
46 | pgoff_t pgoff = vmf->pgoff; |
47 | |
48 | if (!buf) |
49 | return VM_FAULT_OOM; |
50 | |
51 | page = vmalloc_to_page(buf->start + (pgoff << PAGE_SHIFT)); |
52 | if (!page) |
53 | return VM_FAULT_SIGBUS; |
54 | get_page(page); |
55 | vmf->page = page; |
56 | |
57 | 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 | static struct page **relay_alloc_page_array(unsigned int n_pages) |
72 | { |
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); |
77 | } |
78 | |
79 | /* |
80 | * free an array of pointers of struct page |
81 | */ |
82 | static void relay_free_page_array(struct page **array) |
83 | { |
84 | kvfree(array); |
85 | } |
86 | |
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 | */ |
96 | static int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma) |
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; |
108 | vma->vm_flags |= VM_DONTEXPAND; |
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 | * |
120 | * Returns a pointer to the resulting buffer, %NULL if unsuccessful. The |
121 | * passed in size will get page aligned, if it isn't already. |
122 | */ |
123 | static void *relay_alloc_buf(struct rchan_buf *buf, size_t *size) |
124 | { |
125 | void *mem; |
126 | unsigned int i, j, n_pages; |
127 | |
128 | *size = PAGE_ALIGN(*size); |
129 | n_pages = *size >> PAGE_SHIFT; |
130 | |
131 | buf->page_array = relay_alloc_page_array(n_pages); |
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; |
139 | set_page_private(buf->page_array[i], (unsigned long)buf); |
140 | } |
141 | mem = vmap(buf->page_array, n_pages, VM_MAP, PAGE_KERNEL); |
142 | if (!mem) |
143 | goto depopulate; |
144 | |
145 | memset(mem, 0, *size); |
146 | buf->page_count = n_pages; |
147 | return mem; |
148 | |
149 | depopulate: |
150 | for (j = 0; j < i; j++) |
151 | __free_page(buf->page_array[j]); |
152 | relay_free_page_array(buf->page_array); |
153 | return NULL; |
154 | } |
155 | |
156 | /** |
157 | * relay_create_buf - allocate and initialize a channel buffer |
158 | * @chan: the relay channel |
159 | * |
160 | * Returns channel buffer if successful, %NULL otherwise. |
161 | */ |
162 | static struct rchan_buf *relay_create_buf(struct rchan *chan) |
163 | { |
164 | struct rchan_buf *buf; |
165 | |
166 | if (chan->n_subbufs > KMALLOC_MAX_SIZE / sizeof(size_t *)) |
167 | return NULL; |
168 | |
169 | buf = kzalloc(sizeof(struct rchan_buf), GFP_KERNEL); |
170 | if (!buf) |
171 | return NULL; |
172 | buf->padding = kmalloc(chan->n_subbufs * sizeof(size_t *), GFP_KERNEL); |
173 | if (!buf->padding) |
174 | goto free_buf; |
175 | |
176 | buf->start = relay_alloc_buf(buf, &chan->alloc_size); |
177 | if (!buf->start) |
178 | goto free_buf; |
179 | |
180 | buf->chan = chan; |
181 | kref_get(&buf->chan->kref); |
182 | return buf; |
183 | |
184 | free_buf: |
185 | kfree(buf->padding); |
186 | kfree(buf); |
187 | return NULL; |
188 | } |
189 | |
190 | /** |
191 | * relay_destroy_channel - free the channel struct |
192 | * @kref: target kernel reference that contains the relay channel |
193 | * |
194 | * Should only be called from kref_put(). |
195 | */ |
196 | static void relay_destroy_channel(struct kref *kref) |
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 | */ |
206 | static void relay_destroy_buf(struct rchan_buf *buf) |
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]); |
215 | relay_free_page_array(buf->page_array); |
216 | } |
217 | *per_cpu_ptr(chan->buf, buf->cpu) = NULL; |
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 |
225 | * @kref: target kernel reference that contains the relay buffer |
226 | * |
227 | * Removes the file from the filesystem, which also frees the |
228 | * rchan_buf_struct and the channel buffer. Should only be called from |
229 | * kref_put(). |
230 | */ |
231 | static void relay_remove_buf(struct kref *kref) |
232 | { |
233 | struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref); |
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 | */ |
243 | static int relay_buf_empty(struct rchan_buf *buf) |
244 | { |
245 | return (buf->subbufs_produced - buf->subbufs_consumed) ? 0 : 1; |
246 | } |
247 | |
248 | /** |
249 | * relay_buf_full - boolean, is the channel buffer full? |
250 | * @buf: channel buffer |
251 | * |
252 | * Returns 1 if the buffer is full, 0 otherwise. |
253 | */ |
254 | int relay_buf_full(struct rchan_buf *buf) |
255 | { |
256 | size_t ready = buf->subbufs_produced - buf->subbufs_consumed; |
257 | return (ready >= buf->chan->n_subbufs) ? 1 : 0; |
258 | } |
259 | EXPORT_SYMBOL_GPL(relay_buf_full); |
260 | |
261 | /* |
262 | * High-level relay kernel API and associated functions. |
263 | */ |
264 | |
265 | /* |
266 | * rchan_callback implementations defining default channel behavior. Used |
267 | * in place of corresponding NULL values in client callback struct. |
268 | */ |
269 | |
270 | /* |
271 | * subbuf_start() default callback. Does nothing. |
272 | */ |
273 | static int subbuf_start_default_callback (struct rchan_buf *buf, |
274 | void *subbuf, |
275 | void *prev_subbuf, |
276 | size_t prev_padding) |
277 | { |
278 | if (relay_buf_full(buf)) |
279 | return 0; |
280 | |
281 | return 1; |
282 | } |
283 | |
284 | /* |
285 | * buf_mapped() default callback. Does nothing. |
286 | */ |
287 | static void buf_mapped_default_callback(struct rchan_buf *buf, |
288 | struct file *filp) |
289 | { |
290 | } |
291 | |
292 | /* |
293 | * buf_unmapped() default callback. Does nothing. |
294 | */ |
295 | static void buf_unmapped_default_callback(struct rchan_buf *buf, |
296 | struct file *filp) |
297 | { |
298 | } |
299 | |
300 | /* |
301 | * create_buf_file_create() default callback. Does nothing. |
302 | */ |
303 | static struct dentry *create_buf_file_default_callback(const char *filename, |
304 | struct dentry *parent, |
305 | umode_t mode, |
306 | struct rchan_buf *buf, |
307 | int *is_global) |
308 | { |
309 | return NULL; |
310 | } |
311 | |
312 | /* |
313 | * remove_buf_file() default callback. Does nothing. |
314 | */ |
315 | static int remove_buf_file_default_callback(struct dentry *dentry) |
316 | { |
317 | return -EINVAL; |
318 | } |
319 | |
320 | /* relay channel default callbacks */ |
321 | static struct rchan_callbacks default_channel_callbacks = { |
322 | .subbuf_start = subbuf_start_default_callback, |
323 | .buf_mapped = buf_mapped_default_callback, |
324 | .buf_unmapped = buf_unmapped_default_callback, |
325 | .create_buf_file = create_buf_file_default_callback, |
326 | .remove_buf_file = remove_buf_file_default_callback, |
327 | }; |
328 | |
329 | /** |
330 | * wakeup_readers - wake up readers waiting on a channel |
331 | * @work: contains the channel buffer |
332 | * |
333 | * This is the function used to defer reader waking |
334 | */ |
335 | static void wakeup_readers(struct irq_work *work) |
336 | { |
337 | struct rchan_buf *buf; |
338 | |
339 | buf = container_of(work, struct rchan_buf, wakeup_work); |
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 | * |
348 | * See relay_reset() for description of effect. |
349 | */ |
350 | static void __relay_reset(struct rchan_buf *buf, unsigned int init) |
351 | { |
352 | size_t i; |
353 | |
354 | if (init) { |
355 | init_waitqueue_head(&buf->read_wait); |
356 | kref_init(&buf->kref); |
357 | init_irq_work(&buf->wakeup_work, wakeup_readers); |
358 | } else { |
359 | irq_work_sync(&buf->wakeup_work); |
360 | } |
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 | * |
383 | * NOTE. Care should be taken that the channel isn't actually |
384 | * being used by anything when this call is made. |
385 | */ |
386 | void relay_reset(struct rchan *chan) |
387 | { |
388 | struct rchan_buf *buf; |
389 | unsigned int i; |
390 | |
391 | if (!chan) |
392 | return; |
393 | |
394 | if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0))) { |
395 | __relay_reset(buf, 0); |
396 | return; |
397 | } |
398 | |
399 | mutex_lock(&relay_channels_mutex); |
400 | for_each_possible_cpu(i) |
401 | if ((buf = *per_cpu_ptr(chan->buf, i))) |
402 | __relay_reset(buf, 0); |
403 | mutex_unlock(&relay_channels_mutex); |
404 | } |
405 | EXPORT_SYMBOL_GPL(relay_reset); |
406 | |
407 | static inline void relay_set_buf_dentry(struct rchan_buf *buf, |
408 | struct dentry *dentry) |
409 | { |
410 | buf->dentry = dentry; |
411 | d_inode(buf->dentry)->i_size = buf->early_bytes; |
412 | } |
413 | |
414 | static 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 | |
436 | /* |
437 | * relay_open_buf - create a new relay channel buffer |
438 | * |
439 | * used by relay_open() and CPU hotplug. |
440 | */ |
441 | static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu) |
442 | { |
443 | struct rchan_buf *buf = NULL; |
444 | struct dentry *dentry; |
445 | |
446 | if (chan->is_global) |
447 | return *per_cpu_ptr(chan->buf, 0); |
448 | |
449 | buf = relay_create_buf(chan); |
450 | if (!buf) |
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); |
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; |
465 | } |
466 | |
467 | buf->cpu = cpu; |
468 | __relay_reset(buf, 1); |
469 | |
470 | if(chan->is_global) { |
471 | *per_cpu_ptr(chan->buf, 0) = buf; |
472 | buf->cpu = 0; |
473 | } |
474 | |
475 | return buf; |
476 | |
477 | free_buf: |
478 | relay_destroy_buf(buf); |
479 | return NULL; |
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 | */ |
490 | static void relay_close_buf(struct rchan_buf *buf) |
491 | { |
492 | buf->finalized = 1; |
493 | irq_work_sync(&buf->wakeup_work); |
494 | buf->chan->cb->remove_buf_file(buf->dentry); |
495 | kref_put(&buf->kref, relay_remove_buf); |
496 | } |
497 | |
498 | static void setup_callbacks(struct rchan *chan, |
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 | |
519 | int relay_prepare_cpu(unsigned int cpu) |
520 | { |
521 | struct rchan *chan; |
522 | struct rchan_buf *buf; |
523 | |
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; |
533 | } |
534 | *per_cpu_ptr(chan->buf, cpu) = buf; |
535 | } |
536 | mutex_unlock(&relay_channels_mutex); |
537 | return 0; |
538 | } |
539 | |
540 | /** |
541 | * relay_open - create a new relay channel |
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 |
544 | * @subbuf_size: size of sub-buffers |
545 | * @n_subbufs: number of sub-buffers |
546 | * @cb: client callback functions |
547 | * @private_data: user-defined data |
548 | * |
549 | * Returns channel pointer if successful, %NULL otherwise. |
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 |
554 | * permissions will be %S_IRUSR. |
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. |
559 | */ |
560 | struct rchan *relay_open(const char *base_filename, |
561 | struct dentry *parent, |
562 | size_t subbuf_size, |
563 | size_t n_subbufs, |
564 | struct rchan_callbacks *cb, |
565 | void *private_data) |
566 | { |
567 | unsigned int i; |
568 | struct rchan *chan; |
569 | struct rchan_buf *buf; |
570 | |
571 | if (!(subbuf_size && n_subbufs)) |
572 | return NULL; |
573 | if (subbuf_size > UINT_MAX / n_subbufs) |
574 | return NULL; |
575 | |
576 | chan = kzalloc(sizeof(struct rchan), GFP_KERNEL); |
577 | if (!chan) |
578 | return NULL; |
579 | |
580 | chan->buf = alloc_percpu(struct rchan_buf *); |
581 | chan->version = RELAYFS_CHANNEL_VERSION; |
582 | chan->n_subbufs = n_subbufs; |
583 | chan->subbuf_size = subbuf_size; |
584 | chan->alloc_size = PAGE_ALIGN(subbuf_size * n_subbufs); |
585 | chan->parent = parent; |
586 | chan->private_data = private_data; |
587 | if (base_filename) { |
588 | chan->has_base_filename = 1; |
589 | strlcpy(chan->base_filename, base_filename, NAME_MAX); |
590 | } |
591 | setup_callbacks(chan, cb); |
592 | kref_init(&chan->kref); |
593 | |
594 | mutex_lock(&relay_channels_mutex); |
595 | for_each_online_cpu(i) { |
596 | buf = relay_open_buf(chan, i); |
597 | if (!buf) |
598 | goto free_bufs; |
599 | *per_cpu_ptr(chan->buf, i) = buf; |
600 | } |
601 | list_add(&chan->list, &relay_channels); |
602 | mutex_unlock(&relay_channels_mutex); |
603 | |
604 | return chan; |
605 | |
606 | free_bufs: |
607 | for_each_possible_cpu(i) { |
608 | if ((buf = *per_cpu_ptr(chan->buf, i))) |
609 | relay_close_buf(buf); |
610 | } |
611 | |
612 | kref_put(&chan->kref, relay_destroy_channel); |
613 | mutex_unlock(&relay_channels_mutex); |
614 | return NULL; |
615 | } |
616 | EXPORT_SYMBOL_GPL(relay_open); |
617 | |
618 | struct rchan_percpu_buf_dispatcher { |
619 | struct rchan_buf *buf; |
620 | struct dentry *dentry; |
621 | }; |
622 | |
623 | /* Called in atomic context. */ |
624 | static void __relay_set_buf_dentry(void *info) |
625 | { |
626 | struct rchan_percpu_buf_dispatcher *p = info; |
627 | |
628 | relay_set_buf_dentry(p->buf, p->dentry); |
629 | } |
630 | |
631 | /** |
632 | * relay_late_setup_files - triggers file creation |
633 | * @chan: channel to operate on |
634 | * @base_filename: base name of files to create |
635 | * @parent: dentry of parent directory, %NULL for root directory |
636 | * |
637 | * Returns 0 if successful, non-zero otherwise. |
638 | * |
639 | * Use to setup files for a previously buffer-only channel created |
640 | * by relay_open() with a NULL parent dentry. |
641 | * |
642 | * For example, this is useful for perfomring early tracing in kernel, |
643 | * before VFS is up and then exposing the early results once the dentry |
644 | * is available. |
645 | */ |
646 | int relay_late_setup_files(struct rchan *chan, |
647 | const char *base_filename, |
648 | struct dentry *parent) |
649 | { |
650 | int err = 0; |
651 | unsigned int i, curr_cpu; |
652 | unsigned long flags; |
653 | struct dentry *dentry; |
654 | struct rchan_buf *buf; |
655 | struct rchan_percpu_buf_dispatcher disp; |
656 | |
657 | if (!chan || !base_filename) |
658 | return -EINVAL; |
659 | |
660 | strlcpy(chan->base_filename, base_filename, NAME_MAX); |
661 | |
662 | mutex_lock(&relay_channels_mutex); |
663 | /* Is chan already set up? */ |
664 | if (unlikely(chan->has_base_filename)) { |
665 | mutex_unlock(&relay_channels_mutex); |
666 | return -EEXIST; |
667 | } |
668 | chan->has_base_filename = 1; |
669 | chan->parent = parent; |
670 | |
671 | if (chan->is_global) { |
672 | err = -EINVAL; |
673 | buf = *per_cpu_ptr(chan->buf, 0); |
674 | if (!WARN_ON_ONCE(!buf)) { |
675 | dentry = relay_create_buf_file(chan, buf, 0); |
676 | if (dentry && !WARN_ON_ONCE(!chan->is_global)) { |
677 | relay_set_buf_dentry(buf, dentry); |
678 | err = 0; |
679 | } |
680 | } |
681 | mutex_unlock(&relay_channels_mutex); |
682 | return err; |
683 | } |
684 | |
685 | curr_cpu = get_cpu(); |
686 | /* |
687 | * The CPU hotplug notifier ran before us and created buffers with |
688 | * no files associated. So it's safe to call relay_setup_buf_file() |
689 | * on all currently online CPUs. |
690 | */ |
691 | for_each_online_cpu(i) { |
692 | buf = *per_cpu_ptr(chan->buf, i); |
693 | if (unlikely(!buf)) { |
694 | WARN_ONCE(1, KERN_ERR "CPU has no buffer!\n"); |
695 | err = -EINVAL; |
696 | break; |
697 | } |
698 | |
699 | dentry = relay_create_buf_file(chan, buf, i); |
700 | if (unlikely(!dentry)) { |
701 | err = -EINVAL; |
702 | break; |
703 | } |
704 | |
705 | if (curr_cpu == i) { |
706 | local_irq_save(flags); |
707 | relay_set_buf_dentry(buf, dentry); |
708 | local_irq_restore(flags); |
709 | } else { |
710 | disp.buf = buf; |
711 | disp.dentry = dentry; |
712 | smp_mb(); |
713 | /* relay_channels_mutex must be held, so wait. */ |
714 | err = smp_call_function_single(i, |
715 | __relay_set_buf_dentry, |
716 | &disp, 1); |
717 | } |
718 | if (unlikely(err)) |
719 | break; |
720 | } |
721 | put_cpu(); |
722 | mutex_unlock(&relay_channels_mutex); |
723 | |
724 | return err; |
725 | } |
726 | EXPORT_SYMBOL_GPL(relay_late_setup_files); |
727 | |
728 | /** |
729 | * relay_switch_subbuf - switch to a new sub-buffer |
730 | * @buf: channel buffer |
731 | * @length: size of current event |
732 | * |
733 | * Returns either the length passed in or 0 if full. |
734 | * |
735 | * Performs sub-buffer-switch tasks such as invoking callbacks, |
736 | * updating padding counts, waking up readers, etc. |
737 | */ |
738 | size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length) |
739 | { |
740 | void *old, *new; |
741 | size_t old_subbuf, new_subbuf; |
742 | |
743 | if (unlikely(length > buf->chan->subbuf_size)) |
744 | goto toobig; |
745 | |
746 | if (buf->offset != buf->chan->subbuf_size + 1) { |
747 | buf->prev_padding = buf->chan->subbuf_size - buf->offset; |
748 | old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; |
749 | buf->padding[old_subbuf] = buf->prev_padding; |
750 | buf->subbufs_produced++; |
751 | if (buf->dentry) |
752 | d_inode(buf->dentry)->i_size += |
753 | buf->chan->subbuf_size - |
754 | buf->padding[old_subbuf]; |
755 | else |
756 | buf->early_bytes += buf->chan->subbuf_size - |
757 | buf->padding[old_subbuf]; |
758 | smp_mb(); |
759 | if (waitqueue_active(&buf->read_wait)) { |
760 | /* |
761 | * Calling wake_up_interruptible() from here |
762 | * will deadlock if we happen to be logging |
763 | * from the scheduler (trying to re-grab |
764 | * rq->lock), so defer it. |
765 | */ |
766 | irq_work_queue(&buf->wakeup_work); |
767 | } |
768 | } |
769 | |
770 | old = buf->data; |
771 | new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; |
772 | new = buf->start + new_subbuf * buf->chan->subbuf_size; |
773 | buf->offset = 0; |
774 | if (!buf->chan->cb->subbuf_start(buf, new, old, buf->prev_padding)) { |
775 | buf->offset = buf->chan->subbuf_size + 1; |
776 | return 0; |
777 | } |
778 | buf->data = new; |
779 | buf->padding[new_subbuf] = 0; |
780 | |
781 | if (unlikely(length + buf->offset > buf->chan->subbuf_size)) |
782 | goto toobig; |
783 | |
784 | return length; |
785 | |
786 | toobig: |
787 | buf->chan->last_toobig = length; |
788 | return 0; |
789 | } |
790 | EXPORT_SYMBOL_GPL(relay_switch_subbuf); |
791 | |
792 | /** |
793 | * relay_subbufs_consumed - update the buffer's sub-buffers-consumed count |
794 | * @chan: the channel |
795 | * @cpu: the cpu associated with the channel buffer to update |
796 | * @subbufs_consumed: number of sub-buffers to add to current buf's count |
797 | * |
798 | * Adds to the channel buffer's consumed sub-buffer count. |
799 | * subbufs_consumed should be the number of sub-buffers newly consumed, |
800 | * not the total consumed. |
801 | * |
802 | * NOTE. Kernel clients don't need to call this function if the channel |
803 | * mode is 'overwrite'. |
804 | */ |
805 | void relay_subbufs_consumed(struct rchan *chan, |
806 | unsigned int cpu, |
807 | size_t subbufs_consumed) |
808 | { |
809 | struct rchan_buf *buf; |
810 | |
811 | if (!chan || cpu >= NR_CPUS) |
812 | return; |
813 | |
814 | buf = *per_cpu_ptr(chan->buf, cpu); |
815 | if (!buf || subbufs_consumed > chan->n_subbufs) |
816 | return; |
817 | |
818 | if (subbufs_consumed > buf->subbufs_produced - buf->subbufs_consumed) |
819 | buf->subbufs_consumed = buf->subbufs_produced; |
820 | else |
821 | buf->subbufs_consumed += subbufs_consumed; |
822 | } |
823 | EXPORT_SYMBOL_GPL(relay_subbufs_consumed); |
824 | |
825 | /** |
826 | * relay_close - close the channel |
827 | * @chan: the channel |
828 | * |
829 | * Closes all channel buffers and frees the channel. |
830 | */ |
831 | void relay_close(struct rchan *chan) |
832 | { |
833 | struct rchan_buf *buf; |
834 | unsigned int i; |
835 | |
836 | if (!chan) |
837 | return; |
838 | |
839 | mutex_lock(&relay_channels_mutex); |
840 | if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0))) |
841 | relay_close_buf(buf); |
842 | else |
843 | for_each_possible_cpu(i) |
844 | if ((buf = *per_cpu_ptr(chan->buf, i))) |
845 | relay_close_buf(buf); |
846 | |
847 | if (chan->last_toobig) |
848 | printk(KERN_WARNING "relay: one or more items not logged " |
849 | "[item size (%Zd) > sub-buffer size (%Zd)]\n", |
850 | chan->last_toobig, chan->subbuf_size); |
851 | |
852 | list_del(&chan->list); |
853 | kref_put(&chan->kref, relay_destroy_channel); |
854 | mutex_unlock(&relay_channels_mutex); |
855 | } |
856 | EXPORT_SYMBOL_GPL(relay_close); |
857 | |
858 | /** |
859 | * relay_flush - close the channel |
860 | * @chan: the channel |
861 | * |
862 | * Flushes all channel buffers, i.e. forces buffer switch. |
863 | */ |
864 | void relay_flush(struct rchan *chan) |
865 | { |
866 | struct rchan_buf *buf; |
867 | unsigned int i; |
868 | |
869 | if (!chan) |
870 | return; |
871 | |
872 | if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0))) { |
873 | relay_switch_subbuf(buf, 0); |
874 | return; |
875 | } |
876 | |
877 | mutex_lock(&relay_channels_mutex); |
878 | for_each_possible_cpu(i) |
879 | if ((buf = *per_cpu_ptr(chan->buf, i))) |
880 | relay_switch_subbuf(buf, 0); |
881 | mutex_unlock(&relay_channels_mutex); |
882 | } |
883 | EXPORT_SYMBOL_GPL(relay_flush); |
884 | |
885 | /** |
886 | * relay_file_open - open file op for relay files |
887 | * @inode: the inode |
888 | * @filp: the file |
889 | * |
890 | * Increments the channel buffer refcount. |
891 | */ |
892 | static int relay_file_open(struct inode *inode, struct file *filp) |
893 | { |
894 | struct rchan_buf *buf = inode->i_private; |
895 | kref_get(&buf->kref); |
896 | filp->private_data = buf; |
897 | |
898 | return nonseekable_open(inode, filp); |
899 | } |
900 | |
901 | /** |
902 | * relay_file_mmap - mmap file op for relay files |
903 | * @filp: the file |
904 | * @vma: the vma describing what to map |
905 | * |
906 | * Calls upon relay_mmap_buf() to map the file into user space. |
907 | */ |
908 | static int relay_file_mmap(struct file *filp, struct vm_area_struct *vma) |
909 | { |
910 | struct rchan_buf *buf = filp->private_data; |
911 | return relay_mmap_buf(buf, vma); |
912 | } |
913 | |
914 | /** |
915 | * relay_file_poll - poll file op for relay files |
916 | * @filp: the file |
917 | * @wait: poll table |
918 | * |
919 | * Poll implemention. |
920 | */ |
921 | static unsigned int relay_file_poll(struct file *filp, poll_table *wait) |
922 | { |
923 | unsigned int mask = 0; |
924 | struct rchan_buf *buf = filp->private_data; |
925 | |
926 | if (buf->finalized) |
927 | return POLLERR; |
928 | |
929 | if (filp->f_mode & FMODE_READ) { |
930 | poll_wait(filp, &buf->read_wait, wait); |
931 | if (!relay_buf_empty(buf)) |
932 | mask |= POLLIN | POLLRDNORM; |
933 | } |
934 | |
935 | return mask; |
936 | } |
937 | |
938 | /** |
939 | * relay_file_release - release file op for relay files |
940 | * @inode: the inode |
941 | * @filp: the file |
942 | * |
943 | * Decrements the channel refcount, as the filesystem is |
944 | * no longer using it. |
945 | */ |
946 | static int relay_file_release(struct inode *inode, struct file *filp) |
947 | { |
948 | struct rchan_buf *buf = filp->private_data; |
949 | kref_put(&buf->kref, relay_remove_buf); |
950 | |
951 | return 0; |
952 | } |
953 | |
954 | /* |
955 | * relay_file_read_consume - update the consumed count for the buffer |
956 | */ |
957 | static void relay_file_read_consume(struct rchan_buf *buf, |
958 | size_t read_pos, |
959 | size_t bytes_consumed) |
960 | { |
961 | size_t subbuf_size = buf->chan->subbuf_size; |
962 | size_t n_subbufs = buf->chan->n_subbufs; |
963 | size_t read_subbuf; |
964 | |
965 | if (buf->subbufs_produced == buf->subbufs_consumed && |
966 | buf->offset == buf->bytes_consumed) |
967 | return; |
968 | |
969 | if (buf->bytes_consumed + bytes_consumed > subbuf_size) { |
970 | relay_subbufs_consumed(buf->chan, buf->cpu, 1); |
971 | buf->bytes_consumed = 0; |
972 | } |
973 | |
974 | buf->bytes_consumed += bytes_consumed; |
975 | if (!read_pos) |
976 | read_subbuf = buf->subbufs_consumed % n_subbufs; |
977 | else |
978 | read_subbuf = read_pos / buf->chan->subbuf_size; |
979 | if (buf->bytes_consumed + buf->padding[read_subbuf] == subbuf_size) { |
980 | if ((read_subbuf == buf->subbufs_produced % n_subbufs) && |
981 | (buf->offset == subbuf_size)) |
982 | return; |
983 | relay_subbufs_consumed(buf->chan, buf->cpu, 1); |
984 | buf->bytes_consumed = 0; |
985 | } |
986 | } |
987 | |
988 | /* |
989 | * relay_file_read_avail - boolean, are there unconsumed bytes available? |
990 | */ |
991 | static int relay_file_read_avail(struct rchan_buf *buf, size_t read_pos) |
992 | { |
993 | size_t subbuf_size = buf->chan->subbuf_size; |
994 | size_t n_subbufs = buf->chan->n_subbufs; |
995 | size_t produced = buf->subbufs_produced; |
996 | size_t consumed = buf->subbufs_consumed; |
997 | |
998 | relay_file_read_consume(buf, read_pos, 0); |
999 | |
1000 | consumed = buf->subbufs_consumed; |
1001 | |
1002 | if (unlikely(buf->offset > subbuf_size)) { |
1003 | if (produced == consumed) |
1004 | return 0; |
1005 | return 1; |
1006 | } |
1007 | |
1008 | if (unlikely(produced - consumed >= n_subbufs)) { |
1009 | consumed = produced - n_subbufs + 1; |
1010 | buf->subbufs_consumed = consumed; |
1011 | buf->bytes_consumed = 0; |
1012 | } |
1013 | |
1014 | produced = (produced % n_subbufs) * subbuf_size + buf->offset; |
1015 | consumed = (consumed % n_subbufs) * subbuf_size + buf->bytes_consumed; |
1016 | |
1017 | if (consumed > produced) |
1018 | produced += n_subbufs * subbuf_size; |
1019 | |
1020 | if (consumed == produced) { |
1021 | if (buf->offset == subbuf_size && |
1022 | buf->subbufs_produced > buf->subbufs_consumed) |
1023 | return 1; |
1024 | return 0; |
1025 | } |
1026 | |
1027 | return 1; |
1028 | } |
1029 | |
1030 | /** |
1031 | * relay_file_read_subbuf_avail - return bytes available in sub-buffer |
1032 | * @read_pos: file read position |
1033 | * @buf: relay channel buffer |
1034 | */ |
1035 | static size_t relay_file_read_subbuf_avail(size_t read_pos, |
1036 | struct rchan_buf *buf) |
1037 | { |
1038 | size_t padding, avail = 0; |
1039 | size_t read_subbuf, read_offset, write_subbuf, write_offset; |
1040 | size_t subbuf_size = buf->chan->subbuf_size; |
1041 | |
1042 | write_subbuf = (buf->data - buf->start) / subbuf_size; |
1043 | write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset; |
1044 | read_subbuf = read_pos / subbuf_size; |
1045 | read_offset = read_pos % subbuf_size; |
1046 | padding = buf->padding[read_subbuf]; |
1047 | |
1048 | if (read_subbuf == write_subbuf) { |
1049 | if (read_offset + padding < write_offset) |
1050 | avail = write_offset - (read_offset + padding); |
1051 | } else |
1052 | avail = (subbuf_size - padding) - read_offset; |
1053 | |
1054 | return avail; |
1055 | } |
1056 | |
1057 | /** |
1058 | * relay_file_read_start_pos - find the first available byte to read |
1059 | * @read_pos: file read position |
1060 | * @buf: relay channel buffer |
1061 | * |
1062 | * If the @read_pos is in the middle of padding, return the |
1063 | * position of the first actually available byte, otherwise |
1064 | * return the original value. |
1065 | */ |
1066 | static size_t relay_file_read_start_pos(size_t read_pos, |
1067 | struct rchan_buf *buf) |
1068 | { |
1069 | size_t read_subbuf, padding, padding_start, padding_end; |
1070 | size_t subbuf_size = buf->chan->subbuf_size; |
1071 | size_t n_subbufs = buf->chan->n_subbufs; |
1072 | size_t consumed = buf->subbufs_consumed % n_subbufs; |
1073 | |
1074 | if (!read_pos) |
1075 | read_pos = consumed * subbuf_size + buf->bytes_consumed; |
1076 | read_subbuf = read_pos / subbuf_size; |
1077 | padding = buf->padding[read_subbuf]; |
1078 | padding_start = (read_subbuf + 1) * subbuf_size - padding; |
1079 | padding_end = (read_subbuf + 1) * subbuf_size; |
1080 | if (read_pos >= padding_start && read_pos < padding_end) { |
1081 | read_subbuf = (read_subbuf + 1) % n_subbufs; |
1082 | read_pos = read_subbuf * subbuf_size; |
1083 | } |
1084 | |
1085 | return read_pos; |
1086 | } |
1087 | |
1088 | /** |
1089 | * relay_file_read_end_pos - return the new read position |
1090 | * @read_pos: file read position |
1091 | * @buf: relay channel buffer |
1092 | * @count: number of bytes to be read |
1093 | */ |
1094 | static size_t relay_file_read_end_pos(struct rchan_buf *buf, |
1095 | size_t read_pos, |
1096 | size_t count) |
1097 | { |
1098 | size_t read_subbuf, padding, end_pos; |
1099 | size_t subbuf_size = buf->chan->subbuf_size; |
1100 | size_t n_subbufs = buf->chan->n_subbufs; |
1101 | |
1102 | read_subbuf = read_pos / subbuf_size; |
1103 | padding = buf->padding[read_subbuf]; |
1104 | if (read_pos % subbuf_size + count + padding == subbuf_size) |
1105 | end_pos = (read_subbuf + 1) * subbuf_size; |
1106 | else |
1107 | end_pos = read_pos + count; |
1108 | if (end_pos >= subbuf_size * n_subbufs) |
1109 | end_pos = 0; |
1110 | |
1111 | return end_pos; |
1112 | } |
1113 | |
1114 | static ssize_t relay_file_read(struct file *filp, |
1115 | char __user *buffer, |
1116 | size_t count, |
1117 | loff_t *ppos) |
1118 | { |
1119 | struct rchan_buf *buf = filp->private_data; |
1120 | size_t read_start, avail; |
1121 | size_t written = 0; |
1122 | int ret; |
1123 | |
1124 | if (!count) |
1125 | return 0; |
1126 | |
1127 | inode_lock(file_inode(filp)); |
1128 | do { |
1129 | void *from; |
1130 | |
1131 | if (!relay_file_read_avail(buf, *ppos)) |
1132 | break; |
1133 | |
1134 | read_start = relay_file_read_start_pos(*ppos, buf); |
1135 | avail = relay_file_read_subbuf_avail(read_start, buf); |
1136 | if (!avail) |
1137 | break; |
1138 | |
1139 | avail = min(count, avail); |
1140 | from = buf->start + read_start; |
1141 | ret = avail; |
1142 | if (copy_to_user(buffer, from, avail)) |
1143 | break; |
1144 | |
1145 | buffer += ret; |
1146 | written += ret; |
1147 | count -= ret; |
1148 | |
1149 | relay_file_read_consume(buf, read_start, ret); |
1150 | *ppos = relay_file_read_end_pos(buf, read_start, ret); |
1151 | } while (count); |
1152 | inode_unlock(file_inode(filp)); |
1153 | |
1154 | return written; |
1155 | } |
1156 | |
1157 | static void relay_consume_bytes(struct rchan_buf *rbuf, int bytes_consumed) |
1158 | { |
1159 | rbuf->bytes_consumed += bytes_consumed; |
1160 | |
1161 | if (rbuf->bytes_consumed >= rbuf->chan->subbuf_size) { |
1162 | relay_subbufs_consumed(rbuf->chan, rbuf->cpu, 1); |
1163 | rbuf->bytes_consumed %= rbuf->chan->subbuf_size; |
1164 | } |
1165 | } |
1166 | |
1167 | static void relay_pipe_buf_release(struct pipe_inode_info *pipe, |
1168 | struct pipe_buffer *buf) |
1169 | { |
1170 | struct rchan_buf *rbuf; |
1171 | |
1172 | rbuf = (struct rchan_buf *)page_private(buf->page); |
1173 | relay_consume_bytes(rbuf, buf->private); |
1174 | } |
1175 | |
1176 | static const struct pipe_buf_operations relay_pipe_buf_ops = { |
1177 | .can_merge = 0, |
1178 | .confirm = generic_pipe_buf_confirm, |
1179 | .release = relay_pipe_buf_release, |
1180 | .steal = generic_pipe_buf_steal, |
1181 | .get = generic_pipe_buf_get, |
1182 | }; |
1183 | |
1184 | static void relay_page_release(struct splice_pipe_desc *spd, unsigned int i) |
1185 | { |
1186 | } |
1187 | |
1188 | /* |
1189 | * subbuf_splice_actor - splice up to one subbuf's worth of data |
1190 | */ |
1191 | static ssize_t subbuf_splice_actor(struct file *in, |
1192 | loff_t *ppos, |
1193 | struct pipe_inode_info *pipe, |
1194 | size_t len, |
1195 | unsigned int flags, |
1196 | int *nonpad_ret) |
1197 | { |
1198 | unsigned int pidx, poff, total_len, subbuf_pages, nr_pages; |
1199 | struct rchan_buf *rbuf = in->private_data; |
1200 | unsigned int subbuf_size = rbuf->chan->subbuf_size; |
1201 | uint64_t pos = (uint64_t) *ppos; |
1202 | uint32_t alloc_size = (uint32_t) rbuf->chan->alloc_size; |
1203 | size_t read_start = (size_t) do_div(pos, alloc_size); |
1204 | size_t read_subbuf = read_start / subbuf_size; |
1205 | size_t padding = rbuf->padding[read_subbuf]; |
1206 | size_t nonpad_end = read_subbuf * subbuf_size + subbuf_size - padding; |
1207 | struct page *pages[PIPE_DEF_BUFFERS]; |
1208 | struct partial_page partial[PIPE_DEF_BUFFERS]; |
1209 | struct splice_pipe_desc spd = { |
1210 | .pages = pages, |
1211 | .nr_pages = 0, |
1212 | .nr_pages_max = PIPE_DEF_BUFFERS, |
1213 | .partial = partial, |
1214 | .flags = flags, |
1215 | .ops = &relay_pipe_buf_ops, |
1216 | .spd_release = relay_page_release, |
1217 | }; |
1218 | ssize_t ret; |
1219 | |
1220 | if (rbuf->subbufs_produced == rbuf->subbufs_consumed) |
1221 | return 0; |
1222 | if (splice_grow_spd(pipe, &spd)) |
1223 | return -ENOMEM; |
1224 | |
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; |
1230 | |
1231 | subbuf_pages = rbuf->chan->alloc_size >> PAGE_SHIFT; |
1232 | pidx = (read_start / PAGE_SIZE) % subbuf_pages; |
1233 | poff = read_start & ~PAGE_MASK; |
1234 | nr_pages = min_t(unsigned int, subbuf_pages, spd.nr_pages_max); |
1235 | |
1236 | for (total_len = 0; spd.nr_pages < nr_pages; spd.nr_pages++) { |
1237 | unsigned int this_len, this_end, private; |
1238 | unsigned int cur_pos = read_start + total_len; |
1239 | |
1240 | if (!len) |
1241 | break; |
1242 | |
1243 | this_len = min_t(unsigned long, len, PAGE_SIZE - poff); |
1244 | private = this_len; |
1245 | |
1246 | spd.pages[spd.nr_pages] = rbuf->page_array[pidx]; |
1247 | spd.partial[spd.nr_pages].offset = poff; |
1248 | |
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; |
1253 | } |
1254 | spd.partial[spd.nr_pages].len = this_len; |
1255 | spd.partial[spd.nr_pages].private = private; |
1256 | |
1257 | len -= this_len; |
1258 | total_len += this_len; |
1259 | poff = 0; |
1260 | pidx = (pidx + 1) % subbuf_pages; |
1261 | |
1262 | if (this_end >= nonpad_end) { |
1263 | spd.nr_pages++; |
1264 | break; |
1265 | } |
1266 | } |
1267 | |
1268 | ret = 0; |
1269 | if (!spd.nr_pages) |
1270 | goto out; |
1271 | |
1272 | ret = *nonpad_ret = splice_to_pipe(pipe, &spd); |
1273 | if (ret < 0 || ret < total_len) |
1274 | goto out; |
1275 | |
1276 | if (read_start + ret == nonpad_end) |
1277 | ret += padding; |
1278 | |
1279 | out: |
1280 | splice_shrink_spd(&spd); |
1281 | return ret; |
1282 | } |
1283 | |
1284 | static 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 | |
1297 | while (len && !spliced) { |
1298 | ret = subbuf_splice_actor(in, ppos, pipe, len, flags, &nonpad_ret); |
1299 | if (ret < 0) |
1300 | break; |
1301 | else if (!ret) { |
1302 | if (flags & SPLICE_F_NONBLOCK) |
1303 | ret = -EAGAIN; |
1304 | break; |
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; |
1320 | } |
1321 | |
1322 | const struct file_operations relay_file_operations = { |
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, |
1329 | .splice_read = relay_file_splice_read, |
1330 | }; |
1331 | EXPORT_SYMBOL_GPL(relay_file_operations); |
1332 |