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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/module.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 | struct page **array; |
74 | size_t pa_size = n_pages * sizeof(struct page *); |
75 | |
76 | if (pa_size > PAGE_SIZE) { |
77 | array = vmalloc(pa_size); |
78 | if (array) |
79 | memset(array, 0, pa_size); |
80 | } else { |
81 | array = kzalloc(pa_size, GFP_KERNEL); |
82 | } |
83 | return array; |
84 | } |
85 | |
86 | /* |
87 | * free an array of pointers of struct page |
88 | */ |
89 | static void relay_free_page_array(struct page **array) |
90 | { |
91 | if (is_vmalloc_addr(array)) |
92 | vfree(array); |
93 | else |
94 | kfree(array); |
95 | } |
96 | |
97 | /** |
98 | * relay_mmap_buf: - mmap channel buffer to process address space |
99 | * @buf: relay channel buffer |
100 | * @vma: vm_area_struct describing memory to be mapped |
101 | * |
102 | * Returns 0 if ok, negative on error |
103 | * |
104 | * Caller should already have grabbed mmap_sem. |
105 | */ |
106 | static int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma) |
107 | { |
108 | unsigned long length = vma->vm_end - vma->vm_start; |
109 | struct file *filp = vma->vm_file; |
110 | |
111 | if (!buf) |
112 | return -EBADF; |
113 | |
114 | if (length != (unsigned long)buf->chan->alloc_size) |
115 | return -EINVAL; |
116 | |
117 | vma->vm_ops = &relay_file_mmap_ops; |
118 | vma->vm_flags |= VM_DONTEXPAND; |
119 | vma->vm_private_data = buf; |
120 | buf->chan->cb->buf_mapped(buf, filp); |
121 | |
122 | return 0; |
123 | } |
124 | |
125 | /** |
126 | * relay_alloc_buf - allocate a channel buffer |
127 | * @buf: the buffer struct |
128 | * @size: total size of the buffer |
129 | * |
130 | * Returns a pointer to the resulting buffer, %NULL if unsuccessful. The |
131 | * passed in size will get page aligned, if it isn't already. |
132 | */ |
133 | static void *relay_alloc_buf(struct rchan_buf *buf, size_t *size) |
134 | { |
135 | void *mem; |
136 | unsigned int i, j, n_pages; |
137 | |
138 | *size = PAGE_ALIGN(*size); |
139 | n_pages = *size >> PAGE_SHIFT; |
140 | |
141 | buf->page_array = relay_alloc_page_array(n_pages); |
142 | if (!buf->page_array) |
143 | return NULL; |
144 | |
145 | for (i = 0; i < n_pages; i++) { |
146 | buf->page_array[i] = alloc_page(GFP_KERNEL); |
147 | if (unlikely(!buf->page_array[i])) |
148 | goto depopulate; |
149 | set_page_private(buf->page_array[i], (unsigned long)buf); |
150 | } |
151 | mem = vmap(buf->page_array, n_pages, VM_MAP, PAGE_KERNEL); |
152 | if (!mem) |
153 | goto depopulate; |
154 | |
155 | memset(mem, 0, *size); |
156 | buf->page_count = n_pages; |
157 | return mem; |
158 | |
159 | depopulate: |
160 | for (j = 0; j < i; j++) |
161 | __free_page(buf->page_array[j]); |
162 | relay_free_page_array(buf->page_array); |
163 | return NULL; |
164 | } |
165 | |
166 | /** |
167 | * relay_create_buf - allocate and initialize a channel buffer |
168 | * @chan: the relay channel |
169 | * |
170 | * Returns channel buffer if successful, %NULL otherwise. |
171 | */ |
172 | static struct rchan_buf *relay_create_buf(struct rchan *chan) |
173 | { |
174 | struct rchan_buf *buf = kzalloc(sizeof(struct rchan_buf), GFP_KERNEL); |
175 | if (!buf) |
176 | return NULL; |
177 | |
178 | buf->padding = kmalloc(chan->n_subbufs * sizeof(size_t *), GFP_KERNEL); |
179 | if (!buf->padding) |
180 | goto free_buf; |
181 | |
182 | buf->start = relay_alloc_buf(buf, &chan->alloc_size); |
183 | if (!buf->start) |
184 | goto free_buf; |
185 | |
186 | buf->chan = chan; |
187 | kref_get(&buf->chan->kref); |
188 | return buf; |
189 | |
190 | free_buf: |
191 | kfree(buf->padding); |
192 | kfree(buf); |
193 | return NULL; |
194 | } |
195 | |
196 | /** |
197 | * relay_destroy_channel - free the channel struct |
198 | * @kref: target kernel reference that contains the relay channel |
199 | * |
200 | * Should only be called from kref_put(). |
201 | */ |
202 | static void relay_destroy_channel(struct kref *kref) |
203 | { |
204 | struct rchan *chan = container_of(kref, struct rchan, kref); |
205 | kfree(chan); |
206 | } |
207 | |
208 | /** |
209 | * relay_destroy_buf - destroy an rchan_buf struct and associated buffer |
210 | * @buf: the buffer struct |
211 | */ |
212 | static void relay_destroy_buf(struct rchan_buf *buf) |
213 | { |
214 | struct rchan *chan = buf->chan; |
215 | unsigned int i; |
216 | |
217 | if (likely(buf->start)) { |
218 | vunmap(buf->start); |
219 | for (i = 0; i < buf->page_count; i++) |
220 | __free_page(buf->page_array[i]); |
221 | relay_free_page_array(buf->page_array); |
222 | } |
223 | chan->buf[buf->cpu] = NULL; |
224 | kfree(buf->padding); |
225 | kfree(buf); |
226 | kref_put(&chan->kref, relay_destroy_channel); |
227 | } |
228 | |
229 | /** |
230 | * relay_remove_buf - remove a channel buffer |
231 | * @kref: target kernel reference that contains the relay buffer |
232 | * |
233 | * Removes the file from the fileystem, which also frees the |
234 | * rchan_buf_struct and the channel buffer. Should only be called from |
235 | * kref_put(). |
236 | */ |
237 | static void relay_remove_buf(struct kref *kref) |
238 | { |
239 | struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref); |
240 | buf->chan->cb->remove_buf_file(buf->dentry); |
241 | relay_destroy_buf(buf); |
242 | } |
243 | |
244 | /** |
245 | * relay_buf_empty - boolean, is the channel buffer empty? |
246 | * @buf: channel buffer |
247 | * |
248 | * Returns 1 if the buffer is empty, 0 otherwise. |
249 | */ |
250 | static int relay_buf_empty(struct rchan_buf *buf) |
251 | { |
252 | return (buf->subbufs_produced - buf->subbufs_consumed) ? 0 : 1; |
253 | } |
254 | |
255 | /** |
256 | * relay_buf_full - boolean, is the channel buffer full? |
257 | * @buf: channel buffer |
258 | * |
259 | * Returns 1 if the buffer is full, 0 otherwise. |
260 | */ |
261 | int relay_buf_full(struct rchan_buf *buf) |
262 | { |
263 | size_t ready = buf->subbufs_produced - buf->subbufs_consumed; |
264 | return (ready >= buf->chan->n_subbufs) ? 1 : 0; |
265 | } |
266 | EXPORT_SYMBOL_GPL(relay_buf_full); |
267 | |
268 | /* |
269 | * High-level relay kernel API and associated functions. |
270 | */ |
271 | |
272 | /* |
273 | * rchan_callback implementations defining default channel behavior. Used |
274 | * in place of corresponding NULL values in client callback struct. |
275 | */ |
276 | |
277 | /* |
278 | * subbuf_start() default callback. Does nothing. |
279 | */ |
280 | static int subbuf_start_default_callback (struct rchan_buf *buf, |
281 | void *subbuf, |
282 | void *prev_subbuf, |
283 | size_t prev_padding) |
284 | { |
285 | if (relay_buf_full(buf)) |
286 | return 0; |
287 | |
288 | return 1; |
289 | } |
290 | |
291 | /* |
292 | * buf_mapped() default callback. Does nothing. |
293 | */ |
294 | static void buf_mapped_default_callback(struct rchan_buf *buf, |
295 | struct file *filp) |
296 | { |
297 | } |
298 | |
299 | /* |
300 | * buf_unmapped() default callback. Does nothing. |
301 | */ |
302 | static void buf_unmapped_default_callback(struct rchan_buf *buf, |
303 | struct file *filp) |
304 | { |
305 | } |
306 | |
307 | /* |
308 | * create_buf_file_create() default callback. Does nothing. |
309 | */ |
310 | static struct dentry *create_buf_file_default_callback(const char *filename, |
311 | struct dentry *parent, |
312 | int mode, |
313 | struct rchan_buf *buf, |
314 | int *is_global) |
315 | { |
316 | return NULL; |
317 | } |
318 | |
319 | /* |
320 | * remove_buf_file() default callback. Does nothing. |
321 | */ |
322 | static int remove_buf_file_default_callback(struct dentry *dentry) |
323 | { |
324 | return -EINVAL; |
325 | } |
326 | |
327 | /* relay channel default callbacks */ |
328 | static struct rchan_callbacks default_channel_callbacks = { |
329 | .subbuf_start = subbuf_start_default_callback, |
330 | .buf_mapped = buf_mapped_default_callback, |
331 | .buf_unmapped = buf_unmapped_default_callback, |
332 | .create_buf_file = create_buf_file_default_callback, |
333 | .remove_buf_file = remove_buf_file_default_callback, |
334 | }; |
335 | |
336 | /** |
337 | * wakeup_readers - wake up readers waiting on a channel |
338 | * @data: contains the channel buffer |
339 | * |
340 | * This is the timer function used to defer reader waking. |
341 | */ |
342 | static void wakeup_readers(unsigned long data) |
343 | { |
344 | struct rchan_buf *buf = (struct rchan_buf *)data; |
345 | wake_up_interruptible(&buf->read_wait); |
346 | } |
347 | |
348 | /** |
349 | * __relay_reset - reset a channel buffer |
350 | * @buf: the channel buffer |
351 | * @init: 1 if this is a first-time initialization |
352 | * |
353 | * See relay_reset() for description of effect. |
354 | */ |
355 | static void __relay_reset(struct rchan_buf *buf, unsigned int init) |
356 | { |
357 | size_t i; |
358 | |
359 | if (init) { |
360 | init_waitqueue_head(&buf->read_wait); |
361 | kref_init(&buf->kref); |
362 | setup_timer(&buf->timer, wakeup_readers, (unsigned long)buf); |
363 | } else |
364 | del_timer_sync(&buf->timer); |
365 | |
366 | buf->subbufs_produced = 0; |
367 | buf->subbufs_consumed = 0; |
368 | buf->bytes_consumed = 0; |
369 | buf->finalized = 0; |
370 | buf->data = buf->start; |
371 | buf->offset = 0; |
372 | |
373 | for (i = 0; i < buf->chan->n_subbufs; i++) |
374 | buf->padding[i] = 0; |
375 | |
376 | buf->chan->cb->subbuf_start(buf, buf->data, NULL, 0); |
377 | } |
378 | |
379 | /** |
380 | * relay_reset - reset the channel |
381 | * @chan: the channel |
382 | * |
383 | * This has the effect of erasing all data from all channel buffers |
384 | * and restarting the channel in its initial state. The buffers |
385 | * are not freed, so any mappings are still in effect. |
386 | * |
387 | * NOTE. Care should be taken that the channel isn't actually |
388 | * being used by anything when this call is made. |
389 | */ |
390 | void relay_reset(struct rchan *chan) |
391 | { |
392 | unsigned int i; |
393 | |
394 | if (!chan) |
395 | return; |
396 | |
397 | if (chan->is_global && chan->buf[0]) { |
398 | __relay_reset(chan->buf[0], 0); |
399 | return; |
400 | } |
401 | |
402 | mutex_lock(&relay_channels_mutex); |
403 | for_each_possible_cpu(i) |
404 | if (chan->buf[i]) |
405 | __relay_reset(chan->buf[i], 0); |
406 | mutex_unlock(&relay_channels_mutex); |
407 | } |
408 | EXPORT_SYMBOL_GPL(relay_reset); |
409 | |
410 | static inline void relay_set_buf_dentry(struct rchan_buf *buf, |
411 | struct dentry *dentry) |
412 | { |
413 | buf->dentry = dentry; |
414 | buf->dentry->d_inode->i_size = buf->early_bytes; |
415 | } |
416 | |
417 | static struct dentry *relay_create_buf_file(struct rchan *chan, |
418 | struct rchan_buf *buf, |
419 | unsigned int cpu) |
420 | { |
421 | struct dentry *dentry; |
422 | char *tmpname; |
423 | |
424 | tmpname = kzalloc(NAME_MAX + 1, GFP_KERNEL); |
425 | if (!tmpname) |
426 | return NULL; |
427 | snprintf(tmpname, NAME_MAX, "%s%d", chan->base_filename, cpu); |
428 | |
429 | /* Create file in fs */ |
430 | dentry = chan->cb->create_buf_file(tmpname, chan->parent, |
431 | S_IRUSR, buf, |
432 | &chan->is_global); |
433 | |
434 | kfree(tmpname); |
435 | |
436 | return dentry; |
437 | } |
438 | |
439 | /* |
440 | * relay_open_buf - create a new relay channel buffer |
441 | * |
442 | * used by relay_open() and CPU hotplug. |
443 | */ |
444 | static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu) |
445 | { |
446 | struct rchan_buf *buf = NULL; |
447 | struct dentry *dentry; |
448 | |
449 | if (chan->is_global) |
450 | return chan->buf[0]; |
451 | |
452 | buf = relay_create_buf(chan); |
453 | if (!buf) |
454 | return NULL; |
455 | |
456 | if (chan->has_base_filename) { |
457 | dentry = relay_create_buf_file(chan, buf, cpu); |
458 | if (!dentry) |
459 | goto free_buf; |
460 | relay_set_buf_dentry(buf, dentry); |
461 | } |
462 | |
463 | buf->cpu = cpu; |
464 | __relay_reset(buf, 1); |
465 | |
466 | if(chan->is_global) { |
467 | chan->buf[0] = buf; |
468 | buf->cpu = 0; |
469 | } |
470 | |
471 | return buf; |
472 | |
473 | free_buf: |
474 | relay_destroy_buf(buf); |
475 | return NULL; |
476 | } |
477 | |
478 | /** |
479 | * relay_close_buf - close a channel buffer |
480 | * @buf: channel buffer |
481 | * |
482 | * Marks the buffer finalized and restores the default callbacks. |
483 | * The channel buffer and channel buffer data structure are then freed |
484 | * automatically when the last reference is given up. |
485 | */ |
486 | static void relay_close_buf(struct rchan_buf *buf) |
487 | { |
488 | buf->finalized = 1; |
489 | del_timer_sync(&buf->timer); |
490 | kref_put(&buf->kref, relay_remove_buf); |
491 | } |
492 | |
493 | static void setup_callbacks(struct rchan *chan, |
494 | struct rchan_callbacks *cb) |
495 | { |
496 | if (!cb) { |
497 | chan->cb = &default_channel_callbacks; |
498 | return; |
499 | } |
500 | |
501 | if (!cb->subbuf_start) |
502 | cb->subbuf_start = subbuf_start_default_callback; |
503 | if (!cb->buf_mapped) |
504 | cb->buf_mapped = buf_mapped_default_callback; |
505 | if (!cb->buf_unmapped) |
506 | cb->buf_unmapped = buf_unmapped_default_callback; |
507 | if (!cb->create_buf_file) |
508 | cb->create_buf_file = create_buf_file_default_callback; |
509 | if (!cb->remove_buf_file) |
510 | cb->remove_buf_file = remove_buf_file_default_callback; |
511 | chan->cb = cb; |
512 | } |
513 | |
514 | /** |
515 | * relay_hotcpu_callback - CPU hotplug callback |
516 | * @nb: notifier block |
517 | * @action: hotplug action to take |
518 | * @hcpu: CPU number |
519 | * |
520 | * Returns the success/failure of the operation. (%NOTIFY_OK, %NOTIFY_BAD) |
521 | */ |
522 | static int __cpuinit relay_hotcpu_callback(struct notifier_block *nb, |
523 | unsigned long action, |
524 | void *hcpu) |
525 | { |
526 | unsigned int hotcpu = (unsigned long)hcpu; |
527 | struct rchan *chan; |
528 | |
529 | switch(action) { |
530 | case CPU_UP_PREPARE: |
531 | case CPU_UP_PREPARE_FROZEN: |
532 | mutex_lock(&relay_channels_mutex); |
533 | list_for_each_entry(chan, &relay_channels, list) { |
534 | if (chan->buf[hotcpu]) |
535 | continue; |
536 | chan->buf[hotcpu] = relay_open_buf(chan, hotcpu); |
537 | if(!chan->buf[hotcpu]) { |
538 | printk(KERN_ERR |
539 | "relay_hotcpu_callback: cpu %d buffer " |
540 | "creation failed\n", hotcpu); |
541 | mutex_unlock(&relay_channels_mutex); |
542 | return NOTIFY_BAD; |
543 | } |
544 | } |
545 | mutex_unlock(&relay_channels_mutex); |
546 | break; |
547 | case CPU_DEAD: |
548 | case CPU_DEAD_FROZEN: |
549 | /* No need to flush the cpu : will be flushed upon |
550 | * final relay_flush() call. */ |
551 | break; |
552 | } |
553 | return NOTIFY_OK; |
554 | } |
555 | |
556 | /** |
557 | * relay_open - create a new relay channel |
558 | * @base_filename: base name of files to create, %NULL for buffering only |
559 | * @parent: dentry of parent directory, %NULL for root directory or buffer |
560 | * @subbuf_size: size of sub-buffers |
561 | * @n_subbufs: number of sub-buffers |
562 | * @cb: client callback functions |
563 | * @private_data: user-defined data |
564 | * |
565 | * Returns channel pointer if successful, %NULL otherwise. |
566 | * |
567 | * Creates a channel buffer for each cpu using the sizes and |
568 | * attributes specified. The created channel buffer files |
569 | * will be named base_filename0...base_filenameN-1. File |
570 | * permissions will be %S_IRUSR. |
571 | */ |
572 | struct rchan *relay_open(const char *base_filename, |
573 | struct dentry *parent, |
574 | size_t subbuf_size, |
575 | size_t n_subbufs, |
576 | struct rchan_callbacks *cb, |
577 | void *private_data) |
578 | { |
579 | unsigned int i; |
580 | struct rchan *chan; |
581 | |
582 | if (!(subbuf_size && n_subbufs)) |
583 | return NULL; |
584 | |
585 | chan = kzalloc(sizeof(struct rchan), GFP_KERNEL); |
586 | if (!chan) |
587 | return NULL; |
588 | |
589 | chan->version = RELAYFS_CHANNEL_VERSION; |
590 | chan->n_subbufs = n_subbufs; |
591 | chan->subbuf_size = subbuf_size; |
592 | chan->alloc_size = FIX_SIZE(subbuf_size * n_subbufs); |
593 | chan->parent = parent; |
594 | chan->private_data = private_data; |
595 | if (base_filename) { |
596 | chan->has_base_filename = 1; |
597 | strlcpy(chan->base_filename, base_filename, NAME_MAX); |
598 | } |
599 | setup_callbacks(chan, cb); |
600 | kref_init(&chan->kref); |
601 | |
602 | mutex_lock(&relay_channels_mutex); |
603 | for_each_online_cpu(i) { |
604 | chan->buf[i] = relay_open_buf(chan, i); |
605 | if (!chan->buf[i]) |
606 | goto free_bufs; |
607 | } |
608 | list_add(&chan->list, &relay_channels); |
609 | mutex_unlock(&relay_channels_mutex); |
610 | |
611 | return chan; |
612 | |
613 | free_bufs: |
614 | for_each_possible_cpu(i) { |
615 | if (chan->buf[i]) |
616 | relay_close_buf(chan->buf[i]); |
617 | } |
618 | |
619 | kref_put(&chan->kref, relay_destroy_channel); |
620 | mutex_unlock(&relay_channels_mutex); |
621 | return NULL; |
622 | } |
623 | EXPORT_SYMBOL_GPL(relay_open); |
624 | |
625 | struct rchan_percpu_buf_dispatcher { |
626 | struct rchan_buf *buf; |
627 | struct dentry *dentry; |
628 | }; |
629 | |
630 | /* Called in atomic context. */ |
631 | static void __relay_set_buf_dentry(void *info) |
632 | { |
633 | struct rchan_percpu_buf_dispatcher *p = info; |
634 | |
635 | relay_set_buf_dentry(p->buf, p->dentry); |
636 | } |
637 | |
638 | /** |
639 | * relay_late_setup_files - triggers file creation |
640 | * @chan: channel to operate on |
641 | * @base_filename: base name of files to create |
642 | * @parent: dentry of parent directory, %NULL for root directory |
643 | * |
644 | * Returns 0 if successful, non-zero otherwise. |
645 | * |
646 | * Use to setup files for a previously buffer-only channel. |
647 | * Useful to do early tracing in kernel, before VFS is up, for example. |
648 | */ |
649 | int relay_late_setup_files(struct rchan *chan, |
650 | const char *base_filename, |
651 | struct dentry *parent) |
652 | { |
653 | int err = 0; |
654 | unsigned int i, curr_cpu; |
655 | unsigned long flags; |
656 | struct dentry *dentry; |
657 | struct rchan_percpu_buf_dispatcher disp; |
658 | |
659 | if (!chan || !base_filename) |
660 | return -EINVAL; |
661 | |
662 | strlcpy(chan->base_filename, base_filename, NAME_MAX); |
663 | |
664 | mutex_lock(&relay_channels_mutex); |
665 | /* Is chan already set up? */ |
666 | if (unlikely(chan->has_base_filename)) { |
667 | mutex_unlock(&relay_channels_mutex); |
668 | return -EEXIST; |
669 | } |
670 | chan->has_base_filename = 1; |
671 | chan->parent = parent; |
672 | curr_cpu = get_cpu(); |
673 | /* |
674 | * The CPU hotplug notifier ran before us and created buffers with |
675 | * no files associated. So it's safe to call relay_setup_buf_file() |
676 | * on all currently online CPUs. |
677 | */ |
678 | for_each_online_cpu(i) { |
679 | if (unlikely(!chan->buf[i])) { |
680 | WARN_ONCE(1, KERN_ERR "CPU has no buffer!\n"); |
681 | err = -EINVAL; |
682 | break; |
683 | } |
684 | |
685 | dentry = relay_create_buf_file(chan, chan->buf[i], i); |
686 | if (unlikely(!dentry)) { |
687 | err = -EINVAL; |
688 | break; |
689 | } |
690 | |
691 | if (curr_cpu == i) { |
692 | local_irq_save(flags); |
693 | relay_set_buf_dentry(chan->buf[i], dentry); |
694 | local_irq_restore(flags); |
695 | } else { |
696 | disp.buf = chan->buf[i]; |
697 | disp.dentry = dentry; |
698 | smp_mb(); |
699 | /* relay_channels_mutex must be held, so wait. */ |
700 | err = smp_call_function_single(i, |
701 | __relay_set_buf_dentry, |
702 | &disp, 1); |
703 | } |
704 | if (unlikely(err)) |
705 | break; |
706 | } |
707 | put_cpu(); |
708 | mutex_unlock(&relay_channels_mutex); |
709 | |
710 | return err; |
711 | } |
712 | |
713 | /** |
714 | * relay_switch_subbuf - switch to a new sub-buffer |
715 | * @buf: channel buffer |
716 | * @length: size of current event |
717 | * |
718 | * Returns either the length passed in or 0 if full. |
719 | * |
720 | * Performs sub-buffer-switch tasks such as invoking callbacks, |
721 | * updating padding counts, waking up readers, etc. |
722 | */ |
723 | size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length) |
724 | { |
725 | void *old, *new; |
726 | size_t old_subbuf, new_subbuf; |
727 | |
728 | if (unlikely(length > buf->chan->subbuf_size)) |
729 | goto toobig; |
730 | |
731 | if (buf->offset != buf->chan->subbuf_size + 1) { |
732 | buf->prev_padding = buf->chan->subbuf_size - buf->offset; |
733 | old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; |
734 | buf->padding[old_subbuf] = buf->prev_padding; |
735 | buf->subbufs_produced++; |
736 | if (buf->dentry) |
737 | buf->dentry->d_inode->i_size += |
738 | buf->chan->subbuf_size - |
739 | buf->padding[old_subbuf]; |
740 | else |
741 | buf->early_bytes += buf->chan->subbuf_size - |
742 | buf->padding[old_subbuf]; |
743 | smp_mb(); |
744 | if (waitqueue_active(&buf->read_wait)) |
745 | /* |
746 | * Calling wake_up_interruptible() from here |
747 | * will deadlock if we happen to be logging |
748 | * from the scheduler (trying to re-grab |
749 | * rq->lock), so defer it. |
750 | */ |
751 | mod_timer(&buf->timer, jiffies + 1); |
752 | } |
753 | |
754 | old = buf->data; |
755 | new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; |
756 | new = buf->start + new_subbuf * buf->chan->subbuf_size; |
757 | buf->offset = 0; |
758 | if (!buf->chan->cb->subbuf_start(buf, new, old, buf->prev_padding)) { |
759 | buf->offset = buf->chan->subbuf_size + 1; |
760 | return 0; |
761 | } |
762 | buf->data = new; |
763 | buf->padding[new_subbuf] = 0; |
764 | |
765 | if (unlikely(length + buf->offset > buf->chan->subbuf_size)) |
766 | goto toobig; |
767 | |
768 | return length; |
769 | |
770 | toobig: |
771 | buf->chan->last_toobig = length; |
772 | return 0; |
773 | } |
774 | EXPORT_SYMBOL_GPL(relay_switch_subbuf); |
775 | |
776 | /** |
777 | * relay_subbufs_consumed - update the buffer's sub-buffers-consumed count |
778 | * @chan: the channel |
779 | * @cpu: the cpu associated with the channel buffer to update |
780 | * @subbufs_consumed: number of sub-buffers to add to current buf's count |
781 | * |
782 | * Adds to the channel buffer's consumed sub-buffer count. |
783 | * subbufs_consumed should be the number of sub-buffers newly consumed, |
784 | * not the total consumed. |
785 | * |
786 | * NOTE. Kernel clients don't need to call this function if the channel |
787 | * mode is 'overwrite'. |
788 | */ |
789 | void relay_subbufs_consumed(struct rchan *chan, |
790 | unsigned int cpu, |
791 | size_t subbufs_consumed) |
792 | { |
793 | struct rchan_buf *buf; |
794 | |
795 | if (!chan) |
796 | return; |
797 | |
798 | if (cpu >= NR_CPUS || !chan->buf[cpu] || |
799 | subbufs_consumed > chan->n_subbufs) |
800 | return; |
801 | |
802 | buf = chan->buf[cpu]; |
803 | if (subbufs_consumed > buf->subbufs_produced - buf->subbufs_consumed) |
804 | buf->subbufs_consumed = buf->subbufs_produced; |
805 | else |
806 | buf->subbufs_consumed += subbufs_consumed; |
807 | } |
808 | EXPORT_SYMBOL_GPL(relay_subbufs_consumed); |
809 | |
810 | /** |
811 | * relay_close - close the channel |
812 | * @chan: the channel |
813 | * |
814 | * Closes all channel buffers and frees the channel. |
815 | */ |
816 | void relay_close(struct rchan *chan) |
817 | { |
818 | unsigned int i; |
819 | |
820 | if (!chan) |
821 | return; |
822 | |
823 | mutex_lock(&relay_channels_mutex); |
824 | if (chan->is_global && chan->buf[0]) |
825 | relay_close_buf(chan->buf[0]); |
826 | else |
827 | for_each_possible_cpu(i) |
828 | if (chan->buf[i]) |
829 | relay_close_buf(chan->buf[i]); |
830 | |
831 | if (chan->last_toobig) |
832 | printk(KERN_WARNING "relay: one or more items not logged " |
833 | "[item size (%Zd) > sub-buffer size (%Zd)]\n", |
834 | chan->last_toobig, chan->subbuf_size); |
835 | |
836 | list_del(&chan->list); |
837 | kref_put(&chan->kref, relay_destroy_channel); |
838 | mutex_unlock(&relay_channels_mutex); |
839 | } |
840 | EXPORT_SYMBOL_GPL(relay_close); |
841 | |
842 | /** |
843 | * relay_flush - close the channel |
844 | * @chan: the channel |
845 | * |
846 | * Flushes all channel buffers, i.e. forces buffer switch. |
847 | */ |
848 | void relay_flush(struct rchan *chan) |
849 | { |
850 | unsigned int i; |
851 | |
852 | if (!chan) |
853 | return; |
854 | |
855 | if (chan->is_global && chan->buf[0]) { |
856 | relay_switch_subbuf(chan->buf[0], 0); |
857 | return; |
858 | } |
859 | |
860 | mutex_lock(&relay_channels_mutex); |
861 | for_each_possible_cpu(i) |
862 | if (chan->buf[i]) |
863 | relay_switch_subbuf(chan->buf[i], 0); |
864 | mutex_unlock(&relay_channels_mutex); |
865 | } |
866 | EXPORT_SYMBOL_GPL(relay_flush); |
867 | |
868 | /** |
869 | * relay_file_open - open file op for relay files |
870 | * @inode: the inode |
871 | * @filp: the file |
872 | * |
873 | * Increments the channel buffer refcount. |
874 | */ |
875 | static int relay_file_open(struct inode *inode, struct file *filp) |
876 | { |
877 | struct rchan_buf *buf = inode->i_private; |
878 | kref_get(&buf->kref); |
879 | filp->private_data = buf; |
880 | |
881 | return nonseekable_open(inode, filp); |
882 | } |
883 | |
884 | /** |
885 | * relay_file_mmap - mmap file op for relay files |
886 | * @filp: the file |
887 | * @vma: the vma describing what to map |
888 | * |
889 | * Calls upon relay_mmap_buf() to map the file into user space. |
890 | */ |
891 | static int relay_file_mmap(struct file *filp, struct vm_area_struct *vma) |
892 | { |
893 | struct rchan_buf *buf = filp->private_data; |
894 | return relay_mmap_buf(buf, vma); |
895 | } |
896 | |
897 | /** |
898 | * relay_file_poll - poll file op for relay files |
899 | * @filp: the file |
900 | * @wait: poll table |
901 | * |
902 | * Poll implemention. |
903 | */ |
904 | static unsigned int relay_file_poll(struct file *filp, poll_table *wait) |
905 | { |
906 | unsigned int mask = 0; |
907 | struct rchan_buf *buf = filp->private_data; |
908 | |
909 | if (buf->finalized) |
910 | return POLLERR; |
911 | |
912 | if (filp->f_mode & FMODE_READ) { |
913 | poll_wait(filp, &buf->read_wait, wait); |
914 | if (!relay_buf_empty(buf)) |
915 | mask |= POLLIN | POLLRDNORM; |
916 | } |
917 | |
918 | return mask; |
919 | } |
920 | |
921 | /** |
922 | * relay_file_release - release file op for relay files |
923 | * @inode: the inode |
924 | * @filp: the file |
925 | * |
926 | * Decrements the channel refcount, as the filesystem is |
927 | * no longer using it. |
928 | */ |
929 | static int relay_file_release(struct inode *inode, struct file *filp) |
930 | { |
931 | struct rchan_buf *buf = filp->private_data; |
932 | kref_put(&buf->kref, relay_remove_buf); |
933 | |
934 | return 0; |
935 | } |
936 | |
937 | /* |
938 | * relay_file_read_consume - update the consumed count for the buffer |
939 | */ |
940 | static void relay_file_read_consume(struct rchan_buf *buf, |
941 | size_t read_pos, |
942 | size_t bytes_consumed) |
943 | { |
944 | size_t subbuf_size = buf->chan->subbuf_size; |
945 | size_t n_subbufs = buf->chan->n_subbufs; |
946 | size_t read_subbuf; |
947 | |
948 | if (buf->subbufs_produced == buf->subbufs_consumed && |
949 | buf->offset == buf->bytes_consumed) |
950 | return; |
951 | |
952 | if (buf->bytes_consumed + bytes_consumed > subbuf_size) { |
953 | relay_subbufs_consumed(buf->chan, buf->cpu, 1); |
954 | buf->bytes_consumed = 0; |
955 | } |
956 | |
957 | buf->bytes_consumed += bytes_consumed; |
958 | if (!read_pos) |
959 | read_subbuf = buf->subbufs_consumed % n_subbufs; |
960 | else |
961 | read_subbuf = read_pos / buf->chan->subbuf_size; |
962 | if (buf->bytes_consumed + buf->padding[read_subbuf] == subbuf_size) { |
963 | if ((read_subbuf == buf->subbufs_produced % n_subbufs) && |
964 | (buf->offset == subbuf_size)) |
965 | return; |
966 | relay_subbufs_consumed(buf->chan, buf->cpu, 1); |
967 | buf->bytes_consumed = 0; |
968 | } |
969 | } |
970 | |
971 | /* |
972 | * relay_file_read_avail - boolean, are there unconsumed bytes available? |
973 | */ |
974 | static int relay_file_read_avail(struct rchan_buf *buf, size_t read_pos) |
975 | { |
976 | size_t subbuf_size = buf->chan->subbuf_size; |
977 | size_t n_subbufs = buf->chan->n_subbufs; |
978 | size_t produced = buf->subbufs_produced; |
979 | size_t consumed = buf->subbufs_consumed; |
980 | |
981 | relay_file_read_consume(buf, read_pos, 0); |
982 | |
983 | consumed = buf->subbufs_consumed; |
984 | |
985 | if (unlikely(buf->offset > subbuf_size)) { |
986 | if (produced == consumed) |
987 | return 0; |
988 | return 1; |
989 | } |
990 | |
991 | if (unlikely(produced - consumed >= n_subbufs)) { |
992 | consumed = produced - n_subbufs + 1; |
993 | buf->subbufs_consumed = consumed; |
994 | buf->bytes_consumed = 0; |
995 | } |
996 | |
997 | produced = (produced % n_subbufs) * subbuf_size + buf->offset; |
998 | consumed = (consumed % n_subbufs) * subbuf_size + buf->bytes_consumed; |
999 | |
1000 | if (consumed > produced) |
1001 | produced += n_subbufs * subbuf_size; |
1002 | |
1003 | if (consumed == produced) { |
1004 | if (buf->offset == subbuf_size && |
1005 | buf->subbufs_produced > buf->subbufs_consumed) |
1006 | return 1; |
1007 | return 0; |
1008 | } |
1009 | |
1010 | return 1; |
1011 | } |
1012 | |
1013 | /** |
1014 | * relay_file_read_subbuf_avail - return bytes available in sub-buffer |
1015 | * @read_pos: file read position |
1016 | * @buf: relay channel buffer |
1017 | */ |
1018 | static size_t relay_file_read_subbuf_avail(size_t read_pos, |
1019 | struct rchan_buf *buf) |
1020 | { |
1021 | size_t padding, avail = 0; |
1022 | size_t read_subbuf, read_offset, write_subbuf, write_offset; |
1023 | size_t subbuf_size = buf->chan->subbuf_size; |
1024 | |
1025 | write_subbuf = (buf->data - buf->start) / subbuf_size; |
1026 | write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset; |
1027 | read_subbuf = read_pos / subbuf_size; |
1028 | read_offset = read_pos % subbuf_size; |
1029 | padding = buf->padding[read_subbuf]; |
1030 | |
1031 | if (read_subbuf == write_subbuf) { |
1032 | if (read_offset + padding < write_offset) |
1033 | avail = write_offset - (read_offset + padding); |
1034 | } else |
1035 | avail = (subbuf_size - padding) - read_offset; |
1036 | |
1037 | return avail; |
1038 | } |
1039 | |
1040 | /** |
1041 | * relay_file_read_start_pos - find the first available byte to read |
1042 | * @read_pos: file read position |
1043 | * @buf: relay channel buffer |
1044 | * |
1045 | * If the @read_pos is in the middle of padding, return the |
1046 | * position of the first actually available byte, otherwise |
1047 | * return the original value. |
1048 | */ |
1049 | static size_t relay_file_read_start_pos(size_t read_pos, |
1050 | struct rchan_buf *buf) |
1051 | { |
1052 | size_t read_subbuf, padding, padding_start, padding_end; |
1053 | size_t subbuf_size = buf->chan->subbuf_size; |
1054 | size_t n_subbufs = buf->chan->n_subbufs; |
1055 | size_t consumed = buf->subbufs_consumed % n_subbufs; |
1056 | |
1057 | if (!read_pos) |
1058 | read_pos = consumed * subbuf_size + buf->bytes_consumed; |
1059 | read_subbuf = read_pos / subbuf_size; |
1060 | padding = buf->padding[read_subbuf]; |
1061 | padding_start = (read_subbuf + 1) * subbuf_size - padding; |
1062 | padding_end = (read_subbuf + 1) * subbuf_size; |
1063 | if (read_pos >= padding_start && read_pos < padding_end) { |
1064 | read_subbuf = (read_subbuf + 1) % n_subbufs; |
1065 | read_pos = read_subbuf * subbuf_size; |
1066 | } |
1067 | |
1068 | return read_pos; |
1069 | } |
1070 | |
1071 | /** |
1072 | * relay_file_read_end_pos - return the new read position |
1073 | * @read_pos: file read position |
1074 | * @buf: relay channel buffer |
1075 | * @count: number of bytes to be read |
1076 | */ |
1077 | static size_t relay_file_read_end_pos(struct rchan_buf *buf, |
1078 | size_t read_pos, |
1079 | size_t count) |
1080 | { |
1081 | size_t read_subbuf, padding, end_pos; |
1082 | size_t subbuf_size = buf->chan->subbuf_size; |
1083 | size_t n_subbufs = buf->chan->n_subbufs; |
1084 | |
1085 | read_subbuf = read_pos / subbuf_size; |
1086 | padding = buf->padding[read_subbuf]; |
1087 | if (read_pos % subbuf_size + count + padding == subbuf_size) |
1088 | end_pos = (read_subbuf + 1) * subbuf_size; |
1089 | else |
1090 | end_pos = read_pos + count; |
1091 | if (end_pos >= subbuf_size * n_subbufs) |
1092 | end_pos = 0; |
1093 | |
1094 | return end_pos; |
1095 | } |
1096 | |
1097 | /* |
1098 | * subbuf_read_actor - read up to one subbuf's worth of data |
1099 | */ |
1100 | static int subbuf_read_actor(size_t read_start, |
1101 | struct rchan_buf *buf, |
1102 | size_t avail, |
1103 | read_descriptor_t *desc, |
1104 | read_actor_t actor) |
1105 | { |
1106 | void *from; |
1107 | int ret = 0; |
1108 | |
1109 | from = buf->start + read_start; |
1110 | ret = avail; |
1111 | if (copy_to_user(desc->arg.buf, from, avail)) { |
1112 | desc->error = -EFAULT; |
1113 | ret = 0; |
1114 | } |
1115 | desc->arg.data += ret; |
1116 | desc->written += ret; |
1117 | desc->count -= ret; |
1118 | |
1119 | return ret; |
1120 | } |
1121 | |
1122 | typedef int (*subbuf_actor_t) (size_t read_start, |
1123 | struct rchan_buf *buf, |
1124 | size_t avail, |
1125 | read_descriptor_t *desc, |
1126 | read_actor_t actor); |
1127 | |
1128 | /* |
1129 | * relay_file_read_subbufs - read count bytes, bridging subbuf boundaries |
1130 | */ |
1131 | static ssize_t relay_file_read_subbufs(struct file *filp, loff_t *ppos, |
1132 | subbuf_actor_t subbuf_actor, |
1133 | read_actor_t actor, |
1134 | read_descriptor_t *desc) |
1135 | { |
1136 | struct rchan_buf *buf = filp->private_data; |
1137 | size_t read_start, avail; |
1138 | int ret; |
1139 | |
1140 | if (!desc->count) |
1141 | return 0; |
1142 | |
1143 | mutex_lock(&filp->f_path.dentry->d_inode->i_mutex); |
1144 | do { |
1145 | if (!relay_file_read_avail(buf, *ppos)) |
1146 | break; |
1147 | |
1148 | read_start = relay_file_read_start_pos(*ppos, buf); |
1149 | avail = relay_file_read_subbuf_avail(read_start, buf); |
1150 | if (!avail) |
1151 | break; |
1152 | |
1153 | avail = min(desc->count, avail); |
1154 | ret = subbuf_actor(read_start, buf, avail, desc, actor); |
1155 | if (desc->error < 0) |
1156 | break; |
1157 | |
1158 | if (ret) { |
1159 | relay_file_read_consume(buf, read_start, ret); |
1160 | *ppos = relay_file_read_end_pos(buf, read_start, ret); |
1161 | } |
1162 | } while (desc->count && ret); |
1163 | mutex_unlock(&filp->f_path.dentry->d_inode->i_mutex); |
1164 | |
1165 | return desc->written; |
1166 | } |
1167 | |
1168 | static ssize_t relay_file_read(struct file *filp, |
1169 | char __user *buffer, |
1170 | size_t count, |
1171 | loff_t *ppos) |
1172 | { |
1173 | read_descriptor_t desc; |
1174 | desc.written = 0; |
1175 | desc.count = count; |
1176 | desc.arg.buf = buffer; |
1177 | desc.error = 0; |
1178 | return relay_file_read_subbufs(filp, ppos, subbuf_read_actor, |
1179 | NULL, &desc); |
1180 | } |
1181 | |
1182 | static void relay_consume_bytes(struct rchan_buf *rbuf, int bytes_consumed) |
1183 | { |
1184 | rbuf->bytes_consumed += bytes_consumed; |
1185 | |
1186 | if (rbuf->bytes_consumed >= rbuf->chan->subbuf_size) { |
1187 | relay_subbufs_consumed(rbuf->chan, rbuf->cpu, 1); |
1188 | rbuf->bytes_consumed %= rbuf->chan->subbuf_size; |
1189 | } |
1190 | } |
1191 | |
1192 | static void relay_pipe_buf_release(struct pipe_inode_info *pipe, |
1193 | struct pipe_buffer *buf) |
1194 | { |
1195 | struct rchan_buf *rbuf; |
1196 | |
1197 | rbuf = (struct rchan_buf *)page_private(buf->page); |
1198 | relay_consume_bytes(rbuf, buf->private); |
1199 | } |
1200 | |
1201 | static const struct pipe_buf_operations relay_pipe_buf_ops = { |
1202 | .can_merge = 0, |
1203 | .map = generic_pipe_buf_map, |
1204 | .unmap = generic_pipe_buf_unmap, |
1205 | .confirm = generic_pipe_buf_confirm, |
1206 | .release = relay_pipe_buf_release, |
1207 | .steal = generic_pipe_buf_steal, |
1208 | .get = generic_pipe_buf_get, |
1209 | }; |
1210 | |
1211 | static void relay_page_release(struct splice_pipe_desc *spd, unsigned int i) |
1212 | { |
1213 | } |
1214 | |
1215 | /* |
1216 | * subbuf_splice_actor - splice up to one subbuf's worth of data |
1217 | */ |
1218 | static ssize_t subbuf_splice_actor(struct file *in, |
1219 | loff_t *ppos, |
1220 | struct pipe_inode_info *pipe, |
1221 | size_t len, |
1222 | unsigned int flags, |
1223 | int *nonpad_ret) |
1224 | { |
1225 | unsigned int pidx, poff, total_len, subbuf_pages, nr_pages; |
1226 | struct rchan_buf *rbuf = in->private_data; |
1227 | unsigned int subbuf_size = rbuf->chan->subbuf_size; |
1228 | uint64_t pos = (uint64_t) *ppos; |
1229 | uint32_t alloc_size = (uint32_t) rbuf->chan->alloc_size; |
1230 | size_t read_start = (size_t) do_div(pos, alloc_size); |
1231 | size_t read_subbuf = read_start / subbuf_size; |
1232 | size_t padding = rbuf->padding[read_subbuf]; |
1233 | size_t nonpad_end = read_subbuf * subbuf_size + subbuf_size - padding; |
1234 | struct page *pages[PIPE_BUFFERS]; |
1235 | struct partial_page partial[PIPE_BUFFERS]; |
1236 | struct splice_pipe_desc spd = { |
1237 | .pages = pages, |
1238 | .nr_pages = 0, |
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 | |
1249 | /* |
1250 | * Adjust read len, if longer than what is available |
1251 | */ |
1252 | if (len > (subbuf_size - read_start % subbuf_size)) |
1253 | len = subbuf_size - read_start % subbuf_size; |
1254 | |
1255 | subbuf_pages = rbuf->chan->alloc_size >> PAGE_SHIFT; |
1256 | pidx = (read_start / PAGE_SIZE) % subbuf_pages; |
1257 | poff = read_start & ~PAGE_MASK; |
1258 | nr_pages = min_t(unsigned int, subbuf_pages, PIPE_BUFFERS); |
1259 | |
1260 | for (total_len = 0; spd.nr_pages < nr_pages; spd.nr_pages++) { |
1261 | unsigned int this_len, this_end, private; |
1262 | unsigned int cur_pos = read_start + total_len; |
1263 | |
1264 | if (!len) |
1265 | break; |
1266 | |
1267 | this_len = min_t(unsigned long, len, PAGE_SIZE - poff); |
1268 | private = this_len; |
1269 | |
1270 | spd.pages[spd.nr_pages] = rbuf->page_array[pidx]; |
1271 | spd.partial[spd.nr_pages].offset = poff; |
1272 | |
1273 | this_end = cur_pos + this_len; |
1274 | if (this_end >= nonpad_end) { |
1275 | this_len = nonpad_end - cur_pos; |
1276 | private = this_len + padding; |
1277 | } |
1278 | spd.partial[spd.nr_pages].len = this_len; |
1279 | spd.partial[spd.nr_pages].private = private; |
1280 | |
1281 | len -= this_len; |
1282 | total_len += this_len; |
1283 | poff = 0; |
1284 | pidx = (pidx + 1) % subbuf_pages; |
1285 | |
1286 | if (this_end >= nonpad_end) { |
1287 | spd.nr_pages++; |
1288 | break; |
1289 | } |
1290 | } |
1291 | |
1292 | if (!spd.nr_pages) |
1293 | return 0; |
1294 | |
1295 | ret = *nonpad_ret = splice_to_pipe(pipe, &spd); |
1296 | if (ret < 0 || ret < total_len) |
1297 | return ret; |
1298 | |
1299 | if (read_start + ret == nonpad_end) |
1300 | ret += padding; |
1301 | |
1302 | return ret; |
1303 | } |
1304 | |
1305 | static ssize_t relay_file_splice_read(struct file *in, |
1306 | loff_t *ppos, |
1307 | struct pipe_inode_info *pipe, |
1308 | size_t len, |
1309 | unsigned int flags) |
1310 | { |
1311 | ssize_t spliced; |
1312 | int ret; |
1313 | int nonpad_ret = 0; |
1314 | |
1315 | ret = 0; |
1316 | spliced = 0; |
1317 | |
1318 | while (len && !spliced) { |
1319 | ret = subbuf_splice_actor(in, ppos, pipe, len, flags, &nonpad_ret); |
1320 | if (ret < 0) |
1321 | break; |
1322 | else if (!ret) { |
1323 | if (flags & SPLICE_F_NONBLOCK) |
1324 | ret = -EAGAIN; |
1325 | break; |
1326 | } |
1327 | |
1328 | *ppos += ret; |
1329 | if (ret > len) |
1330 | len = 0; |
1331 | else |
1332 | len -= ret; |
1333 | spliced += nonpad_ret; |
1334 | nonpad_ret = 0; |
1335 | } |
1336 | |
1337 | if (spliced) |
1338 | return spliced; |
1339 | |
1340 | return ret; |
1341 | } |
1342 | |
1343 | const struct file_operations relay_file_operations = { |
1344 | .open = relay_file_open, |
1345 | .poll = relay_file_poll, |
1346 | .mmap = relay_file_mmap, |
1347 | .read = relay_file_read, |
1348 | .llseek = no_llseek, |
1349 | .release = relay_file_release, |
1350 | .splice_read = relay_file_splice_read, |
1351 | }; |
1352 | EXPORT_SYMBOL_GPL(relay_file_operations); |
1353 | |
1354 | static __init int relay_init(void) |
1355 | { |
1356 | |
1357 | hotcpu_notifier(relay_hotcpu_callback, 0); |
1358 | return 0; |
1359 | } |
1360 | |
1361 | early_initcall(relay_init); |
1362 |
Branches:
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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