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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 | if (is_vmalloc_addr(array)) |
85 | vfree(array); |
86 | else |
87 | kfree(array); |
88 | } |
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 | static int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma) |
100 | { |
101 | unsigned long length = vma->vm_end - vma->vm_start; |
102 | struct file *filp = vma->vm_file; |
103 | |
104 | if (!buf) |
105 | return -EBADF; |
106 | |
107 | if (length != (unsigned long)buf->chan->alloc_size) |
108 | return -EINVAL; |
109 | |
110 | vma->vm_ops = &relay_file_mmap_ops; |
111 | vma->vm_flags |= VM_DONTEXPAND; |
112 | vma->vm_private_data = buf; |
113 | buf->chan->cb->buf_mapped(buf, filp); |
114 | |
115 | 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 | 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 | *size = PAGE_ALIGN(*size); |
132 | n_pages = *size >> PAGE_SHIFT; |
133 | |
134 | buf->page_array = relay_alloc_page_array(n_pages); |
135 | if (!buf->page_array) |
136 | return NULL; |
137 | |
138 | for (i = 0; i < n_pages; i++) { |
139 | buf->page_array[i] = alloc_page(GFP_KERNEL); |
140 | if (unlikely(!buf->page_array[i])) |
141 | goto depopulate; |
142 | set_page_private(buf->page_array[i], (unsigned long)buf); |
143 | } |
144 | mem = vmap(buf->page_array, n_pages, VM_MAP, PAGE_KERNEL); |
145 | if (!mem) |
146 | goto depopulate; |
147 | |
148 | memset(mem, 0, *size); |
149 | buf->page_count = n_pages; |
150 | return mem; |
151 | |
152 | depopulate: |
153 | for (j = 0; j < i; j++) |
154 | __free_page(buf->page_array[j]); |
155 | relay_free_page_array(buf->page_array); |
156 | 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 | static struct rchan_buf *relay_create_buf(struct rchan *chan) |
166 | { |
167 | struct rchan_buf *buf; |
168 | |
169 | if (chan->n_subbufs > UINT_MAX / sizeof(size_t *)) |
170 | return NULL; |
171 | |
172 | buf = kzalloc(sizeof(struct rchan_buf), GFP_KERNEL); |
173 | if (!buf) |
174 | return NULL; |
175 | buf->padding = kmalloc(chan->n_subbufs * sizeof(size_t *), GFP_KERNEL); |
176 | if (!buf->padding) |
177 | goto free_buf; |
178 | |
179 | buf->start = relay_alloc_buf(buf, &chan->alloc_size); |
180 | if (!buf->start) |
181 | goto free_buf; |
182 | |
183 | buf->chan = chan; |
184 | kref_get(&buf->chan->kref); |
185 | return buf; |
186 | |
187 | free_buf: |
188 | kfree(buf->padding); |
189 | kfree(buf); |
190 | 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 | static void relay_destroy_channel(struct kref *kref) |
200 | { |
201 | struct rchan *chan = container_of(kref, struct rchan, kref); |
202 | kfree(chan); |
203 | } |
204 | |
205 | /** |
206 | * relay_destroy_buf - destroy an rchan_buf struct and associated buffer |
207 | * @buf: the buffer struct |
208 | */ |
209 | static void relay_destroy_buf(struct rchan_buf *buf) |
210 | { |
211 | struct rchan *chan = buf->chan; |
212 | unsigned int i; |
213 | |
214 | if (likely(buf->start)) { |
215 | vunmap(buf->start); |
216 | for (i = 0; i < buf->page_count; i++) |
217 | __free_page(buf->page_array[i]); |
218 | relay_free_page_array(buf->page_array); |
219 | } |
220 | chan->buf[buf->cpu] = NULL; |
221 | kfree(buf->padding); |
222 | kfree(buf); |
223 | kref_put(&chan->kref, relay_destroy_channel); |
224 | } |
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 fileystem, which also frees the |
231 | * rchan_buf_struct and the channel buffer. Should only be called from |
232 | * kref_put(). |
233 | */ |
234 | static void relay_remove_buf(struct kref *kref) |
235 | { |
236 | struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref); |
237 | buf->chan->cb->remove_buf_file(buf->dentry); |
238 | relay_destroy_buf(buf); |
239 | } |
240 | |
241 | /** |
242 | * relay_buf_empty - boolean, is the channel buffer empty? |
243 | * @buf: channel buffer |
244 | * |
245 | * Returns 1 if the buffer is empty, 0 otherwise. |
246 | */ |
247 | static int relay_buf_empty(struct rchan_buf *buf) |
248 | { |
249 | return (buf->subbufs_produced - buf->subbufs_consumed) ? 0 : 1; |
250 | } |
251 | |
252 | /** |
253 | * relay_buf_full - boolean, is the channel buffer full? |
254 | * @buf: channel buffer |
255 | * |
256 | * Returns 1 if the buffer is full, 0 otherwise. |
257 | */ |
258 | int relay_buf_full(struct rchan_buf *buf) |
259 | { |
260 | size_t ready = buf->subbufs_produced - buf->subbufs_consumed; |
261 | return (ready >= buf->chan->n_subbufs) ? 1 : 0; |
262 | } |
263 | EXPORT_SYMBOL_GPL(relay_buf_full); |
264 | |
265 | /* |
266 | * High-level relay kernel API and associated functions. |
267 | */ |
268 | |
269 | /* |
270 | * rchan_callback implementations defining default channel behavior. Used |
271 | * in place of corresponding NULL values in client callback struct. |
272 | */ |
273 | |
274 | /* |
275 | * subbuf_start() default callback. Does nothing. |
276 | */ |
277 | static int subbuf_start_default_callback (struct rchan_buf *buf, |
278 | void *subbuf, |
279 | void *prev_subbuf, |
280 | size_t prev_padding) |
281 | { |
282 | if (relay_buf_full(buf)) |
283 | return 0; |
284 | |
285 | return 1; |
286 | } |
287 | |
288 | /* |
289 | * buf_mapped() default callback. Does nothing. |
290 | */ |
291 | static void buf_mapped_default_callback(struct rchan_buf *buf, |
292 | struct file *filp) |
293 | { |
294 | } |
295 | |
296 | /* |
297 | * buf_unmapped() default callback. Does nothing. |
298 | */ |
299 | static void buf_unmapped_default_callback(struct rchan_buf *buf, |
300 | struct file *filp) |
301 | { |
302 | } |
303 | |
304 | /* |
305 | * create_buf_file_create() default callback. Does nothing. |
306 | */ |
307 | static struct dentry *create_buf_file_default_callback(const char *filename, |
308 | struct dentry *parent, |
309 | umode_t mode, |
310 | struct rchan_buf *buf, |
311 | int *is_global) |
312 | { |
313 | return NULL; |
314 | } |
315 | |
316 | /* |
317 | * remove_buf_file() default callback. Does nothing. |
318 | */ |
319 | static int remove_buf_file_default_callback(struct dentry *dentry) |
320 | { |
321 | return -EINVAL; |
322 | } |
323 | |
324 | /* relay channel default callbacks */ |
325 | static struct rchan_callbacks default_channel_callbacks = { |
326 | .subbuf_start = subbuf_start_default_callback, |
327 | .buf_mapped = buf_mapped_default_callback, |
328 | .buf_unmapped = buf_unmapped_default_callback, |
329 | .create_buf_file = create_buf_file_default_callback, |
330 | .remove_buf_file = remove_buf_file_default_callback, |
331 | }; |
332 | |
333 | /** |
334 | * wakeup_readers - wake up readers waiting on a channel |
335 | * @data: contains the channel buffer |
336 | * |
337 | * This is the timer function used to defer reader waking. |
338 | */ |
339 | static void wakeup_readers(unsigned long data) |
340 | { |
341 | struct rchan_buf *buf = (struct rchan_buf *)data; |
342 | wake_up_interruptible(&buf->read_wait); |
343 | } |
344 | |
345 | /** |
346 | * __relay_reset - reset a channel buffer |
347 | * @buf: the channel buffer |
348 | * @init: 1 if this is a first-time initialization |
349 | * |
350 | * See relay_reset() for description of effect. |
351 | */ |
352 | static void __relay_reset(struct rchan_buf *buf, unsigned int init) |
353 | { |
354 | size_t i; |
355 | |
356 | if (init) { |
357 | init_waitqueue_head(&buf->read_wait); |
358 | kref_init(&buf->kref); |
359 | setup_timer(&buf->timer, wakeup_readers, (unsigned long)buf); |
360 | } else |
361 | del_timer_sync(&buf->timer); |
362 | |
363 | buf->subbufs_produced = 0; |
364 | buf->subbufs_consumed = 0; |
365 | buf->bytes_consumed = 0; |
366 | buf->finalized = 0; |
367 | buf->data = buf->start; |
368 | buf->offset = 0; |
369 | |
370 | for (i = 0; i < buf->chan->n_subbufs; i++) |
371 | buf->padding[i] = 0; |
372 | |
373 | buf->chan->cb->subbuf_start(buf, buf->data, NULL, 0); |
374 | } |
375 | |
376 | /** |
377 | * relay_reset - reset the channel |
378 | * @chan: the channel |
379 | * |
380 | * This has the effect of erasing all data from all channel buffers |
381 | * and restarting the channel in its initial state. The buffers |
382 | * are not freed, so any mappings are still in effect. |
383 | * |
384 | * NOTE. Care should be taken that the channel isn't actually |
385 | * being used by anything when this call is made. |
386 | */ |
387 | void relay_reset(struct rchan *chan) |
388 | { |
389 | unsigned int i; |
390 | |
391 | if (!chan) |
392 | return; |
393 | |
394 | if (chan->is_global && chan->buf[0]) { |
395 | __relay_reset(chan->buf[0], 0); |
396 | return; |
397 | } |
398 | |
399 | mutex_lock(&relay_channels_mutex); |
400 | for_each_possible_cpu(i) |
401 | if (chan->buf[i]) |
402 | __relay_reset(chan->buf[i], 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 | buf->dentry->d_inode->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 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 | } |
459 | |
460 | buf->cpu = cpu; |
461 | __relay_reset(buf, 1); |
462 | |
463 | if(chan->is_global) { |
464 | chan->buf[0] = buf; |
465 | buf->cpu = 0; |
466 | } |
467 | |
468 | return buf; |
469 | |
470 | free_buf: |
471 | relay_destroy_buf(buf); |
472 | return NULL; |
473 | } |
474 | |
475 | /** |
476 | * relay_close_buf - close a channel buffer |
477 | * @buf: channel buffer |
478 | * |
479 | * Marks the buffer finalized and restores the default callbacks. |
480 | * The channel buffer and channel buffer data structure are then freed |
481 | * automatically when the last reference is given up. |
482 | */ |
483 | static void relay_close_buf(struct rchan_buf *buf) |
484 | { |
485 | buf->finalized = 1; |
486 | del_timer_sync(&buf->timer); |
487 | kref_put(&buf->kref, relay_remove_buf); |
488 | } |
489 | |
490 | static void setup_callbacks(struct rchan *chan, |
491 | struct rchan_callbacks *cb) |
492 | { |
493 | if (!cb) { |
494 | chan->cb = &default_channel_callbacks; |
495 | return; |
496 | } |
497 | |
498 | if (!cb->subbuf_start) |
499 | cb->subbuf_start = subbuf_start_default_callback; |
500 | if (!cb->buf_mapped) |
501 | cb->buf_mapped = buf_mapped_default_callback; |
502 | if (!cb->buf_unmapped) |
503 | cb->buf_unmapped = buf_unmapped_default_callback; |
504 | if (!cb->create_buf_file) |
505 | cb->create_buf_file = create_buf_file_default_callback; |
506 | if (!cb->remove_buf_file) |
507 | cb->remove_buf_file = remove_buf_file_default_callback; |
508 | 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 __cpuinit 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 | 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 | if (!(subbuf_size && n_subbufs)) |
580 | return NULL; |
581 | if (subbuf_size > UINT_MAX / n_subbufs) |
582 | return NULL; |
583 | |
584 | chan = kzalloc(sizeof(struct rchan), GFP_KERNEL); |
585 | if (!chan) |
586 | return NULL; |
587 | |
588 | chan->version = RELAYFS_CHANNEL_VERSION; |
589 | chan->n_subbufs = n_subbufs; |
590 | chan->subbuf_size = subbuf_size; |
591 | chan->alloc_size = FIX_SIZE(subbuf_size * n_subbufs); |
592 | chan->parent = parent; |
593 | chan->private_data = private_data; |
594 | if (base_filename) { |
595 | chan->has_base_filename = 1; |
596 | strlcpy(chan->base_filename, base_filename, NAME_MAX); |
597 | } |
598 | setup_callbacks(chan, cb); |
599 | kref_init(&chan->kref); |
600 | |
601 | mutex_lock(&relay_channels_mutex); |
602 | for_each_online_cpu(i) { |
603 | chan->buf[i] = relay_open_buf(chan, i); |
604 | if (!chan->buf[i]) |
605 | goto free_bufs; |
606 | } |
607 | list_add(&chan->list, &relay_channels); |
608 | mutex_unlock(&relay_channels_mutex); |
609 | |
610 | return chan; |
611 | |
612 | free_bufs: |
613 | for_each_possible_cpu(i) { |
614 | if (chan->buf[i]) |
615 | relay_close_buf(chan->buf[i]); |
616 | } |
617 | |
618 | kref_put(&chan->kref, relay_destroy_channel); |
619 | mutex_unlock(&relay_channels_mutex); |
620 | 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 | static void __relay_set_buf_dentry(void *info) |
631 | { |
632 | struct rchan_percpu_buf_dispatcher *p = info; |
633 | |
634 | relay_set_buf_dentry(p->buf, p->dentry); |
635 | } |
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 | 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 | 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? */ |
665 | if (unlikely(chan->has_base_filename)) { |
666 | mutex_unlock(&relay_channels_mutex); |
667 | return -EEXIST; |
668 | } |
669 | chan->has_base_filename = 1; |
670 | chan->parent = parent; |
671 | 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 | for_each_online_cpu(i) { |
678 | if (unlikely(!chan->buf[i])) { |
679 | WARN_ONCE(1, KERN_ERR "CPU has no buffer!\n"); |
680 | err = -EINVAL; |
681 | break; |
682 | } |
683 | |
684 | dentry = relay_create_buf_file(chan, chan->buf[i], i); |
685 | if (unlikely(!dentry)) { |
686 | err = -EINVAL; |
687 | break; |
688 | } |
689 | |
690 | if (curr_cpu == i) { |
691 | local_irq_save(flags); |
692 | relay_set_buf_dentry(chan->buf[i], dentry); |
693 | local_irq_restore(flags); |
694 | } else { |
695 | disp.buf = chan->buf[i]; |
696 | disp.dentry = dentry; |
697 | smp_mb(); |
698 | /* relay_channels_mutex must be held, so wait. */ |
699 | err = smp_call_function_single(i, |
700 | __relay_set_buf_dentry, |
701 | &disp, 1); |
702 | } |
703 | if (unlikely(err)) |
704 | break; |
705 | } |
706 | put_cpu(); |
707 | mutex_unlock(&relay_channels_mutex); |
708 | |
709 | 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 | 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 | if (unlikely(length > buf->chan->subbuf_size)) |
728 | goto toobig; |
729 | |
730 | if (buf->offset != buf->chan->subbuf_size + 1) { |
731 | buf->prev_padding = buf->chan->subbuf_size - buf->offset; |
732 | old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; |
733 | buf->padding[old_subbuf] = buf->prev_padding; |
734 | buf->subbufs_produced++; |
735 | if (buf->dentry) |
736 | buf->dentry->d_inode->i_size += |
737 | buf->chan->subbuf_size - |
738 | buf->padding[old_subbuf]; |
739 | else |
740 | buf->early_bytes += buf->chan->subbuf_size - |
741 | buf->padding[old_subbuf]; |
742 | smp_mb(); |
743 | 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 | mod_timer(&buf->timer, jiffies + 1); |
751 | } |
752 | |
753 | old = buf->data; |
754 | new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; |
755 | new = buf->start + new_subbuf * buf->chan->subbuf_size; |
756 | buf->offset = 0; |
757 | if (!buf->chan->cb->subbuf_start(buf, new, old, buf->prev_padding)) { |
758 | buf->offset = buf->chan->subbuf_size + 1; |
759 | return 0; |
760 | } |
761 | buf->data = new; |
762 | buf->padding[new_subbuf] = 0; |
763 | |
764 | if (unlikely(length + buf->offset > buf->chan->subbuf_size)) |
765 | goto toobig; |
766 | |
767 | return length; |
768 | |
769 | toobig: |
770 | buf->chan->last_toobig = length; |
771 | 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 | void relay_subbufs_consumed(struct rchan *chan, |
789 | unsigned int cpu, |
790 | size_t subbufs_consumed) |
791 | { |
792 | struct rchan_buf *buf; |
793 | |
794 | if (!chan) |
795 | return; |
796 | |
797 | if (cpu >= NR_CPUS || !chan->buf[cpu] || |
798 | subbufs_consumed > chan->n_subbufs) |
799 | return; |
800 | |
801 | buf = chan->buf[cpu]; |
802 | if (subbufs_consumed > buf->subbufs_produced - buf->subbufs_consumed) |
803 | buf->subbufs_consumed = buf->subbufs_produced; |
804 | else |
805 | 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 | void relay_close(struct rchan *chan) |
816 | { |
817 | unsigned int i; |
818 | |
819 | if (!chan) |
820 | return; |
821 | |
822 | mutex_lock(&relay_channels_mutex); |
823 | if (chan->is_global && chan->buf[0]) |
824 | relay_close_buf(chan->buf[0]); |
825 | else |
826 | for_each_possible_cpu(i) |
827 | if (chan->buf[i]) |
828 | relay_close_buf(chan->buf[i]); |
829 | |
830 | if (chan->last_toobig) |
831 | 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 | kref_put(&chan->kref, relay_destroy_channel); |
837 | 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 | void relay_flush(struct rchan *chan) |
848 | { |
849 | unsigned int i; |
850 | |
851 | if (!chan) |
852 | return; |
853 | |
854 | if (chan->is_global && chan->buf[0]) { |
855 | relay_switch_subbuf(chan->buf[0], 0); |
856 | return; |
857 | } |
858 | |
859 | mutex_lock(&relay_channels_mutex); |
860 | for_each_possible_cpu(i) |
861 | if (chan->buf[i]) |
862 | relay_switch_subbuf(chan->buf[i], 0); |
863 | 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 | static int relay_file_open(struct inode *inode, struct file *filp) |
875 | { |
876 | struct rchan_buf *buf = inode->i_private; |
877 | kref_get(&buf->kref); |
878 | filp->private_data = buf; |
879 | |
880 | 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 | static int relay_file_mmap(struct file *filp, struct vm_area_struct *vma) |
891 | { |
892 | struct rchan_buf *buf = filp->private_data; |
893 | 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 | static unsigned int relay_file_poll(struct file *filp, poll_table *wait) |
904 | { |
905 | unsigned int mask = 0; |
906 | struct rchan_buf *buf = filp->private_data; |
907 | |
908 | if (buf->finalized) |
909 | return POLLERR; |
910 | |
911 | if (filp->f_mode & FMODE_READ) { |
912 | poll_wait(filp, &buf->read_wait, wait); |
913 | if (!relay_buf_empty(buf)) |
914 | mask |= POLLIN | POLLRDNORM; |
915 | } |
916 | |
917 | 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 | static int relay_file_release(struct inode *inode, struct file *filp) |
929 | { |
930 | struct rchan_buf *buf = filp->private_data; |
931 | kref_put(&buf->kref, relay_remove_buf); |
932 | |
933 | return 0; |
934 | } |
935 | |
936 | /* |
937 | * relay_file_read_consume - update the consumed count for the buffer |
938 | */ |
939 | static void relay_file_read_consume(struct rchan_buf *buf, |
940 | size_t read_pos, |
941 | size_t bytes_consumed) |
942 | { |
943 | size_t subbuf_size = buf->chan->subbuf_size; |
944 | size_t n_subbufs = buf->chan->n_subbufs; |
945 | size_t read_subbuf; |
946 | |
947 | if (buf->subbufs_produced == buf->subbufs_consumed && |
948 | buf->offset == buf->bytes_consumed) |
949 | return; |
950 | |
951 | if (buf->bytes_consumed + bytes_consumed > subbuf_size) { |
952 | relay_subbufs_consumed(buf->chan, buf->cpu, 1); |
953 | buf->bytes_consumed = 0; |
954 | } |
955 | |
956 | buf->bytes_consumed += bytes_consumed; |
957 | if (!read_pos) |
958 | read_subbuf = buf->subbufs_consumed % n_subbufs; |
959 | else |
960 | read_subbuf = read_pos / buf->chan->subbuf_size; |
961 | if (buf->bytes_consumed + buf->padding[read_subbuf] == subbuf_size) { |
962 | if ((read_subbuf == buf->subbufs_produced % n_subbufs) && |
963 | (buf->offset == subbuf_size)) |
964 | return; |
965 | relay_subbufs_consumed(buf->chan, buf->cpu, 1); |
966 | buf->bytes_consumed = 0; |
967 | } |
968 | } |
969 | |
970 | /* |
971 | * relay_file_read_avail - boolean, are there unconsumed bytes available? |
972 | */ |
973 | static int relay_file_read_avail(struct rchan_buf *buf, size_t read_pos) |
974 | { |
975 | size_t subbuf_size = buf->chan->subbuf_size; |
976 | size_t n_subbufs = buf->chan->n_subbufs; |
977 | size_t produced = buf->subbufs_produced; |
978 | size_t consumed = buf->subbufs_consumed; |
979 | |
980 | relay_file_read_consume(buf, read_pos, 0); |
981 | |
982 | consumed = buf->subbufs_consumed; |
983 | |
984 | if (unlikely(buf->offset > subbuf_size)) { |
985 | if (produced == consumed) |
986 | return 0; |
987 | return 1; |
988 | } |
989 | |
990 | if (unlikely(produced - consumed >= n_subbufs)) { |
991 | consumed = produced - n_subbufs + 1; |
992 | buf->subbufs_consumed = consumed; |
993 | buf->bytes_consumed = 0; |
994 | } |
995 | |
996 | produced = (produced % n_subbufs) * subbuf_size + buf->offset; |
997 | consumed = (consumed % n_subbufs) * subbuf_size + buf->bytes_consumed; |
998 | |
999 | if (consumed > produced) |
1000 | produced += n_subbufs * subbuf_size; |
1001 | |
1002 | if (consumed == produced) { |
1003 | if (buf->offset == subbuf_size && |
1004 | buf->subbufs_produced > buf->subbufs_consumed) |
1005 | return 1; |
1006 | 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 | 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 | size_t subbuf_size = buf->chan->subbuf_size; |
1023 | |
1024 | write_subbuf = (buf->data - buf->start) / subbuf_size; |
1025 | write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset; |
1026 | read_subbuf = read_pos / subbuf_size; |
1027 | read_offset = read_pos % subbuf_size; |
1028 | padding = buf->padding[read_subbuf]; |
1029 | |
1030 | if (read_subbuf == write_subbuf) { |
1031 | if (read_offset + padding < write_offset) |
1032 | avail = write_offset - (read_offset + padding); |
1033 | } else |
1034 | avail = (subbuf_size - padding) - read_offset; |
1035 | |
1036 | 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 | 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 | size_t subbuf_size = buf->chan->subbuf_size; |
1053 | size_t n_subbufs = buf->chan->n_subbufs; |
1054 | size_t consumed = buf->subbufs_consumed % n_subbufs; |
1055 | |
1056 | if (!read_pos) |
1057 | read_pos = consumed * subbuf_size + buf->bytes_consumed; |
1058 | read_subbuf = read_pos / subbuf_size; |
1059 | padding = buf->padding[read_subbuf]; |
1060 | padding_start = (read_subbuf + 1) * subbuf_size - padding; |
1061 | padding_end = (read_subbuf + 1) * subbuf_size; |
1062 | if (read_pos >= padding_start && read_pos < padding_end) { |
1063 | read_subbuf = (read_subbuf + 1) % n_subbufs; |
1064 | read_pos = read_subbuf * subbuf_size; |
1065 | } |
1066 | |
1067 | 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 | size_t subbuf_size = buf->chan->subbuf_size; |
1082 | size_t n_subbufs = buf->chan->n_subbufs; |
1083 | |
1084 | read_subbuf = read_pos / subbuf_size; |
1085 | padding = buf->padding[read_subbuf]; |
1086 | if (read_pos % subbuf_size + count + padding == subbuf_size) |
1087 | end_pos = (read_subbuf + 1) * subbuf_size; |
1088 | else |
1089 | end_pos = read_pos + count; |
1090 | 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 | static int subbuf_read_actor(size_t read_start, |
1100 | struct rchan_buf *buf, |
1101 | size_t avail, |
1102 | read_descriptor_t *desc, |
1103 | read_actor_t actor) |
1104 | { |
1105 | void *from; |
1106 | int ret = 0; |
1107 | |
1108 | from = buf->start + read_start; |
1109 | ret = avail; |
1110 | if (copy_to_user(desc->arg.buf, from, avail)) { |
1111 | desc->error = -EFAULT; |
1112 | ret = 0; |
1113 | } |
1114 | desc->arg.data += ret; |
1115 | desc->written += ret; |
1116 | desc->count -= ret; |
1117 | |
1118 | return ret; |
1119 | } |
1120 | |
1121 | typedef int (*subbuf_actor_t) (size_t read_start, |
1122 | struct rchan_buf *buf, |
1123 | size_t avail, |
1124 | read_descriptor_t *desc, |
1125 | read_actor_t actor); |
1126 | |
1127 | /* |
1128 | * relay_file_read_subbufs - read count bytes, bridging subbuf boundaries |
1129 | */ |
1130 | static ssize_t relay_file_read_subbufs(struct file *filp, loff_t *ppos, |
1131 | subbuf_actor_t subbuf_actor, |
1132 | read_actor_t actor, |
1133 | read_descriptor_t *desc) |
1134 | { |
1135 | struct rchan_buf *buf = filp->private_data; |
1136 | size_t read_start, avail; |
1137 | int ret; |
1138 | |
1139 | if (!desc->count) |
1140 | return 0; |
1141 | |
1142 | mutex_lock(&file_inode(filp)->i_mutex); |
1143 | do { |
1144 | if (!relay_file_read_avail(buf, *ppos)) |
1145 | break; |
1146 | |
1147 | read_start = relay_file_read_start_pos(*ppos, buf); |
1148 | avail = relay_file_read_subbuf_avail(read_start, buf); |
1149 | if (!avail) |
1150 | break; |
1151 | |
1152 | avail = min(desc->count, avail); |
1153 | ret = subbuf_actor(read_start, buf, avail, desc, actor); |
1154 | if (desc->error < 0) |
1155 | break; |
1156 | |
1157 | if (ret) { |
1158 | relay_file_read_consume(buf, read_start, ret); |
1159 | *ppos = relay_file_read_end_pos(buf, read_start, ret); |
1160 | } |
1161 | } while (desc->count && ret); |
1162 | mutex_unlock(&file_inode(filp)->i_mutex); |
1163 | |
1164 | return desc->written; |
1165 | } |
1166 | |
1167 | static ssize_t relay_file_read(struct file *filp, |
1168 | char __user *buffer, |
1169 | size_t count, |
1170 | loff_t *ppos) |
1171 | { |
1172 | read_descriptor_t desc; |
1173 | desc.written = 0; |
1174 | desc.count = count; |
1175 | desc.arg.buf = buffer; |
1176 | desc.error = 0; |
1177 | return relay_file_read_subbufs(filp, ppos, subbuf_read_actor, |
1178 | NULL, &desc); |
1179 | } |
1180 | |
1181 | static void relay_consume_bytes(struct rchan_buf *rbuf, int bytes_consumed) |
1182 | { |
1183 | rbuf->bytes_consumed += bytes_consumed; |
1184 | |
1185 | if (rbuf->bytes_consumed >= rbuf->chan->subbuf_size) { |
1186 | relay_subbufs_consumed(rbuf->chan, rbuf->cpu, 1); |
1187 | rbuf->bytes_consumed %= rbuf->chan->subbuf_size; |
1188 | } |
1189 | } |
1190 | |
1191 | static void relay_pipe_buf_release(struct pipe_inode_info *pipe, |
1192 | struct pipe_buffer *buf) |
1193 | { |
1194 | struct rchan_buf *rbuf; |
1195 | |
1196 | rbuf = (struct rchan_buf *)page_private(buf->page); |
1197 | relay_consume_bytes(rbuf, buf->private); |
1198 | } |
1199 | |
1200 | static const struct pipe_buf_operations relay_pipe_buf_ops = { |
1201 | .can_merge = 0, |
1202 | .map = generic_pipe_buf_map, |
1203 | .unmap = generic_pipe_buf_unmap, |
1204 | .confirm = generic_pipe_buf_confirm, |
1205 | .release = relay_pipe_buf_release, |
1206 | .steal = generic_pipe_buf_steal, |
1207 | .get = generic_pipe_buf_get, |
1208 | }; |
1209 | |
1210 | static void relay_page_release(struct splice_pipe_desc *spd, unsigned int i) |
1211 | { |
1212 | } |
1213 | |
1214 | /* |
1215 | * subbuf_splice_actor - splice up to one subbuf's worth of data |
1216 | */ |
1217 | static ssize_t subbuf_splice_actor(struct file *in, |
1218 | loff_t *ppos, |
1219 | struct pipe_inode_info *pipe, |
1220 | size_t len, |
1221 | unsigned int flags, |
1222 | int *nonpad_ret) |
1223 | { |
1224 | unsigned int pidx, poff, total_len, subbuf_pages, nr_pages; |
1225 | struct rchan_buf *rbuf = in->private_data; |
1226 | unsigned int subbuf_size = rbuf->chan->subbuf_size; |
1227 | uint64_t pos = (uint64_t) *ppos; |
1228 | uint32_t alloc_size = (uint32_t) rbuf->chan->alloc_size; |
1229 | size_t read_start = (size_t) do_div(pos, alloc_size); |
1230 | size_t read_subbuf = read_start / subbuf_size; |
1231 | size_t padding = rbuf->padding[read_subbuf]; |
1232 | size_t nonpad_end = read_subbuf * subbuf_size + subbuf_size - padding; |
1233 | struct page *pages[PIPE_DEF_BUFFERS]; |
1234 | struct partial_page partial[PIPE_DEF_BUFFERS]; |
1235 | struct splice_pipe_desc spd = { |
1236 | .pages = pages, |
1237 | .nr_pages = 0, |
1238 | .nr_pages_max = PIPE_DEF_BUFFERS, |
1239 | .partial = partial, |
1240 | .flags = flags, |
1241 | .ops = &relay_pipe_buf_ops, |
1242 | .spd_release = relay_page_release, |
1243 | }; |
1244 | ssize_t ret; |
1245 | |
1246 | if (rbuf->subbufs_produced == rbuf->subbufs_consumed) |
1247 | return 0; |
1248 | if (splice_grow_spd(pipe, &spd)) |
1249 | return -ENOMEM; |
1250 | |
1251 | /* |
1252 | * Adjust read len, if longer than what is available |
1253 | */ |
1254 | if (len > (subbuf_size - read_start % subbuf_size)) |
1255 | len = subbuf_size - read_start % subbuf_size; |
1256 | |
1257 | subbuf_pages = rbuf->chan->alloc_size >> PAGE_SHIFT; |
1258 | pidx = (read_start / PAGE_SIZE) % subbuf_pages; |
1259 | poff = read_start & ~PAGE_MASK; |
1260 | nr_pages = min_t(unsigned int, subbuf_pages, pipe->buffers); |
1261 | |
1262 | for (total_len = 0; spd.nr_pages < nr_pages; spd.nr_pages++) { |
1263 | unsigned int this_len, this_end, private; |
1264 | unsigned int cur_pos = read_start + total_len; |
1265 | |
1266 | if (!len) |
1267 | break; |
1268 | |
1269 | this_len = min_t(unsigned long, len, PAGE_SIZE - poff); |
1270 | private = this_len; |
1271 | |
1272 | spd.pages[spd.nr_pages] = rbuf->page_array[pidx]; |
1273 | spd.partial[spd.nr_pages].offset = poff; |
1274 | |
1275 | this_end = cur_pos + this_len; |
1276 | if (this_end >= nonpad_end) { |
1277 | this_len = nonpad_end - cur_pos; |
1278 | private = this_len + padding; |
1279 | } |
1280 | spd.partial[spd.nr_pages].len = this_len; |
1281 | spd.partial[spd.nr_pages].private = private; |
1282 | |
1283 | len -= this_len; |
1284 | total_len += this_len; |
1285 | poff = 0; |
1286 | pidx = (pidx + 1) % subbuf_pages; |
1287 | |
1288 | if (this_end >= nonpad_end) { |
1289 | spd.nr_pages++; |
1290 | break; |
1291 | } |
1292 | } |
1293 | |
1294 | ret = 0; |
1295 | if (!spd.nr_pages) |
1296 | goto out; |
1297 | |
1298 | ret = *nonpad_ret = splice_to_pipe(pipe, &spd); |
1299 | if (ret < 0 || ret < total_len) |
1300 | goto out; |
1301 | |
1302 | if (read_start + ret == nonpad_end) |
1303 | ret += padding; |
1304 | |
1305 | out: |
1306 | splice_shrink_spd(&spd); |
1307 | return ret; |
1308 | } |
1309 | |
1310 | static ssize_t relay_file_splice_read(struct file *in, |
1311 | loff_t *ppos, |
1312 | struct pipe_inode_info *pipe, |
1313 | size_t len, |
1314 | unsigned int flags) |
1315 | { |
1316 | ssize_t spliced; |
1317 | int ret; |
1318 | int nonpad_ret = 0; |
1319 | |
1320 | ret = 0; |
1321 | spliced = 0; |
1322 | |
1323 | while (len && !spliced) { |
1324 | ret = subbuf_splice_actor(in, ppos, pipe, len, flags, &nonpad_ret); |
1325 | if (ret < 0) |
1326 | break; |
1327 | else if (!ret) { |
1328 | if (flags & SPLICE_F_NONBLOCK) |
1329 | ret = -EAGAIN; |
1330 | break; |
1331 | } |
1332 | |
1333 | *ppos += ret; |
1334 | if (ret > len) |
1335 | len = 0; |
1336 | else |
1337 | len -= ret; |
1338 | spliced += nonpad_ret; |
1339 | nonpad_ret = 0; |
1340 | } |
1341 | |
1342 | if (spliced) |
1343 | return spliced; |
1344 | |
1345 | return ret; |
1346 | } |
1347 | |
1348 | const struct file_operations relay_file_operations = { |
1349 | .open = relay_file_open, |
1350 | .poll = relay_file_poll, |
1351 | .mmap = relay_file_mmap, |
1352 | .read = relay_file_read, |
1353 | .llseek = no_llseek, |
1354 | .release = relay_file_release, |
1355 | .splice_read = relay_file_splice_read, |
1356 | }; |
1357 | EXPORT_SYMBOL_GPL(relay_file_operations); |
1358 | |
1359 | static __init int relay_init(void) |
1360 | { |
1361 | |
1362 | hotcpu_notifier(relay_hotcpu_callback, 0); |
1363 | return 0; |
1364 | } |
1365 | |
1366 | early_initcall(relay_init); |
1367 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
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Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9