blob: 8f18d314a96a49a1e9fc6c4cf1c5bead5c96a787 [file] [log] [blame]
Jens Axboeb86ff9812006-03-23 19:56:55 +01001/*
2 * Public API and common code for kernel->userspace relay file support.
3 *
Jesper Juhlc9b3feb2007-07-31 00:39:18 -07004 * See Documentation/filesystems/relay.txt for an overview.
Jens Axboeb86ff9812006-03-23 19:56:55 +01005 *
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.
Mathieu Desnoyers23c88752007-02-10 01:45:05 -080010 * November 2006 - CPU hotplug support by Mathieu Desnoyers
11 * (mathieu.desnoyers@polymtl.ca)
Jens Axboeb86ff9812006-03-23 19:56:55 +010012 *
13 * This file is released under the GPL.
14 */
15#include <linux/errno.h>
16#include <linux/stddef.h>
17#include <linux/slab.h>
Paul Gortmaker9984de12011-05-23 14:51:41 -040018#include <linux/export.h>
Jens Axboeb86ff9812006-03-23 19:56:55 +010019#include <linux/string.h>
20#include <linux/relay.h>
21#include <linux/vmalloc.h>
22#include <linux/mm.h>
Mathieu Desnoyers23c88752007-02-10 01:45:05 -080023#include <linux/cpu.h>
Jens Axboed6b29d72007-06-04 09:59:47 +020024#include <linux/splice.h>
Mathieu Desnoyers23c88752007-02-10 01:45:05 -080025
26/* list of open channels, for cpu hotplug */
27static DEFINE_MUTEX(relay_channels_mutex);
28static LIST_HEAD(relay_channels);
Jens Axboeb86ff9812006-03-23 19:56:55 +010029
30/*
31 * close() vm_op implementation for relay file mapping.
32 */
33static void relay_file_mmap_close(struct vm_area_struct *vma)
34{
35 struct rchan_buf *buf = vma->vm_private_data;
36 buf->chan->cb->buf_unmapped(buf, vma->vm_file);
37}
38
39/*
Nick Piggina1e09612008-02-06 01:37:34 -080040 * fault() vm_op implementation for relay file mapping.
Jens Axboeb86ff9812006-03-23 19:56:55 +010041 */
Nick Piggina1e09612008-02-06 01:37:34 -080042static int relay_buf_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
Jens Axboeb86ff9812006-03-23 19:56:55 +010043{
44 struct page *page;
45 struct rchan_buf *buf = vma->vm_private_data;
Nick Piggina1e09612008-02-06 01:37:34 -080046 pgoff_t pgoff = vmf->pgoff;
Jens Axboeb86ff9812006-03-23 19:56:55 +010047
Jens Axboeb86ff9812006-03-23 19:56:55 +010048 if (!buf)
Nick Piggina1e09612008-02-06 01:37:34 -080049 return VM_FAULT_OOM;
Jens Axboeb86ff9812006-03-23 19:56:55 +010050
Nick Piggina1e09612008-02-06 01:37:34 -080051 page = vmalloc_to_page(buf->start + (pgoff << PAGE_SHIFT));
Jens Axboeb86ff9812006-03-23 19:56:55 +010052 if (!page)
Nick Piggina1e09612008-02-06 01:37:34 -080053 return VM_FAULT_SIGBUS;
Jens Axboeb86ff9812006-03-23 19:56:55 +010054 get_page(page);
Nick Piggina1e09612008-02-06 01:37:34 -080055 vmf->page = page;
Jens Axboeb86ff9812006-03-23 19:56:55 +010056
Nick Piggina1e09612008-02-06 01:37:34 -080057 return 0;
Jens Axboeb86ff9812006-03-23 19:56:55 +010058}
59
60/*
61 * vm_ops for relay file mappings.
62 */
Alexey Dobriyanf0f37e22009-09-27 22:29:37 +040063static const struct vm_operations_struct relay_file_mmap_ops = {
Nick Piggina1e09612008-02-06 01:37:34 -080064 .fault = relay_buf_fault,
Jens Axboeb86ff9812006-03-23 19:56:55 +010065 .close = relay_file_mmap_close,
66};
67
Masami Hiramatsu68ab3d82008-04-29 01:03:46 -070068/*
69 * allocate an array of pointers of struct page
70 */
71static struct page **relay_alloc_page_array(unsigned int n_pages)
72{
Jesper Juhl408af872010-11-04 21:44:41 +010073 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);
Masami Hiramatsu68ab3d82008-04-29 01:03:46 -070077}
78
79/*
80 * free an array of pointers of struct page
81 */
82static void relay_free_page_array(struct page **array)
83{
Pekka Enberg200f1ce2015-06-30 14:59:06 -070084 kvfree(array);
Masami Hiramatsu68ab3d82008-04-29 01:03:46 -070085}
86
Jens Axboeb86ff9812006-03-23 19:56:55 +010087/**
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 */
Adrian Bunk01c55ed2007-07-19 01:48:32 -070096static int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma)
Jens Axboeb86ff9812006-03-23 19:56:55 +010097{
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;
Nick Piggin2f987352008-02-02 03:08:53 +0100108 vma->vm_flags |= VM_DONTEXPAND;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100109 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 *
Randy Dunlap4c78a662006-09-29 01:59:10 -0700120 * Returns a pointer to the resulting buffer, %NULL if unsuccessful. The
Jens Axboe221415d2006-03-23 19:57:55 +0100121 * passed in size will get page aligned, if it isn't already.
Jens Axboeb86ff9812006-03-23 19:56:55 +0100122 */
Jens Axboe221415d2006-03-23 19:57:55 +0100123static void *relay_alloc_buf(struct rchan_buf *buf, size_t *size)
Jens Axboeb86ff9812006-03-23 19:56:55 +0100124{
125 void *mem;
126 unsigned int i, j, n_pages;
127
Jens Axboe221415d2006-03-23 19:57:55 +0100128 *size = PAGE_ALIGN(*size);
129 n_pages = *size >> PAGE_SHIFT;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100130
Masami Hiramatsu68ab3d82008-04-29 01:03:46 -0700131 buf->page_array = relay_alloc_page_array(n_pages);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100132 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;
Tom Zanussiebf99092007-06-04 09:12:05 +0200139 set_page_private(buf->page_array[i], (unsigned long)buf);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100140 }
141 mem = vmap(buf->page_array, n_pages, VM_MAP, PAGE_KERNEL);
142 if (!mem)
143 goto depopulate;
144
Jens Axboe221415d2006-03-23 19:57:55 +0100145 memset(mem, 0, *size);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100146 buf->page_count = n_pages;
147 return mem;
148
149depopulate:
150 for (j = 0; j < i; j++)
151 __free_page(buf->page_array[j]);
Masami Hiramatsu68ab3d82008-04-29 01:03:46 -0700152 relay_free_page_array(buf->page_array);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100153 return NULL;
154}
155
156/**
157 * relay_create_buf - allocate and initialize a channel buffer
Randy Dunlap4c78a662006-09-29 01:59:10 -0700158 * @chan: the relay channel
Jens Axboeb86ff9812006-03-23 19:56:55 +0100159 *
Randy Dunlap4c78a662006-09-29 01:59:10 -0700160 * Returns channel buffer if successful, %NULL otherwise.
Jens Axboeb86ff9812006-03-23 19:56:55 +0100161 */
Adrian Bunk01c55ed2007-07-19 01:48:32 -0700162static struct rchan_buf *relay_create_buf(struct rchan *chan)
Jens Axboeb86ff9812006-03-23 19:56:55 +0100163{
Dan Carpenterf6302f12012-02-10 09:03:58 +0100164 struct rchan_buf *buf;
165
166 if (chan->n_subbufs > UINT_MAX / sizeof(size_t *))
Jens Axboeb86ff9812006-03-23 19:56:55 +0100167 return NULL;
168
Dan Carpenterf6302f12012-02-10 09:03:58 +0100169 buf = kzalloc(sizeof(struct rchan_buf), GFP_KERNEL);
170 if (!buf)
171 return NULL;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100172 buf->padding = kmalloc(chan->n_subbufs * sizeof(size_t *), GFP_KERNEL);
173 if (!buf->padding)
174 goto free_buf;
175
Jens Axboe221415d2006-03-23 19:57:55 +0100176 buf->start = relay_alloc_buf(buf, &chan->alloc_size);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100177 if (!buf->start)
178 goto free_buf;
179
180 buf->chan = chan;
181 kref_get(&buf->chan->kref);
182 return buf;
183
184free_buf:
185 kfree(buf->padding);
186 kfree(buf);
187 return NULL;
188}
189
190/**
191 * relay_destroy_channel - free the channel struct
Randy Dunlap4c78a662006-09-29 01:59:10 -0700192 * @kref: target kernel reference that contains the relay channel
Jens Axboeb86ff9812006-03-23 19:56:55 +0100193 *
194 * Should only be called from kref_put().
195 */
Adrian Bunk01c55ed2007-07-19 01:48:32 -0700196static void relay_destroy_channel(struct kref *kref)
Jens Axboeb86ff9812006-03-23 19:56:55 +0100197{
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 */
Adrian Bunk01c55ed2007-07-19 01:48:32 -0700206static void relay_destroy_buf(struct rchan_buf *buf)
Jens Axboeb86ff9812006-03-23 19:56:55 +0100207{
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]);
Masami Hiramatsu68ab3d82008-04-29 01:03:46 -0700215 relay_free_page_array(buf->page_array);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100216 }
Akash Goel017c59c2016-09-02 21:47:38 +0200217 *per_cpu_ptr(chan->buf, buf->cpu) = NULL;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100218 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
Randy Dunlap4c78a662006-09-29 01:59:10 -0700225 * @kref: target kernel reference that contains the relay buffer
Jens Axboeb86ff9812006-03-23 19:56:55 +0100226 *
Masanari Iidae2278672014-02-18 22:54:36 +0900227 * Removes the file from the filesystem, which also frees the
Jens Axboeb86ff9812006-03-23 19:56:55 +0100228 * rchan_buf_struct and the channel buffer. Should only be called from
229 * kref_put().
230 */
Adrian Bunk01c55ed2007-07-19 01:48:32 -0700231static void relay_remove_buf(struct kref *kref)
Jens Axboeb86ff9812006-03-23 19:56:55 +0100232{
233 struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100234 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 */
Adrian Bunk01c55ed2007-07-19 01:48:32 -0700243static int relay_buf_empty(struct rchan_buf *buf)
Jens Axboeb86ff9812006-03-23 19:56:55 +0100244{
245 return (buf->subbufs_produced - buf->subbufs_consumed) ? 0 : 1;
246}
Jens Axboeb86ff9812006-03-23 19:56:55 +0100247
248/**
249 * relay_buf_full - boolean, is the channel buffer full?
250 * @buf: channel buffer
251 *
252 * Returns 1 if the buffer is full, 0 otherwise.
253 */
254int relay_buf_full(struct rchan_buf *buf)
255{
256 size_t ready = buf->subbufs_produced - buf->subbufs_consumed;
257 return (ready >= buf->chan->n_subbufs) ? 1 : 0;
258}
259EXPORT_SYMBOL_GPL(relay_buf_full);
260
261/*
262 * High-level relay kernel API and associated functions.
263 */
264
265/*
266 * rchan_callback implementations defining default channel behavior. Used
267 * in place of corresponding NULL values in client callback struct.
268 */
269
270/*
271 * subbuf_start() default callback. Does nothing.
272 */
273static int subbuf_start_default_callback (struct rchan_buf *buf,
274 void *subbuf,
275 void *prev_subbuf,
276 size_t prev_padding)
277{
278 if (relay_buf_full(buf))
279 return 0;
280
281 return 1;
282}
283
284/*
285 * buf_mapped() default callback. Does nothing.
286 */
287static void buf_mapped_default_callback(struct rchan_buf *buf,
288 struct file *filp)
289{
290}
291
292/*
293 * buf_unmapped() default callback. Does nothing.
294 */
295static void buf_unmapped_default_callback(struct rchan_buf *buf,
296 struct file *filp)
297{
298}
299
300/*
301 * create_buf_file_create() default callback. Does nothing.
302 */
303static struct dentry *create_buf_file_default_callback(const char *filename,
304 struct dentry *parent,
Al Virof4ae40a2011-07-24 04:33:43 -0400305 umode_t mode,
Jens Axboeb86ff9812006-03-23 19:56:55 +0100306 struct rchan_buf *buf,
307 int *is_global)
308{
309 return NULL;
310}
311
312/*
313 * remove_buf_file() default callback. Does nothing.
314 */
315static int remove_buf_file_default_callback(struct dentry *dentry)
316{
317 return -EINVAL;
318}
319
320/* relay channel default callbacks */
321static struct rchan_callbacks default_channel_callbacks = {
322 .subbuf_start = subbuf_start_default_callback,
323 .buf_mapped = buf_mapped_default_callback,
324 .buf_unmapped = buf_unmapped_default_callback,
325 .create_buf_file = create_buf_file_default_callback,
326 .remove_buf_file = remove_buf_file_default_callback,
327};
328
329/**
330 * wakeup_readers - wake up readers waiting on a channel
Peter Zijlstra26b56792016-10-11 13:54:33 -0700331 * @work: contains the channel buffer
Jens Axboeb86ff9812006-03-23 19:56:55 +0100332 *
Peter Zijlstra26b56792016-10-11 13:54:33 -0700333 * This is the function used to defer reader waking
Jens Axboeb86ff9812006-03-23 19:56:55 +0100334 */
Peter Zijlstra26b56792016-10-11 13:54:33 -0700335static void wakeup_readers(struct irq_work *work)
Jens Axboeb86ff9812006-03-23 19:56:55 +0100336{
Peter Zijlstra26b56792016-10-11 13:54:33 -0700337 struct rchan_buf *buf;
338
339 buf = container_of(work, struct rchan_buf, wakeup_work);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100340 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 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800348 * See relay_reset() for description of effect.
Jens Axboeb86ff9812006-03-23 19:56:55 +0100349 */
Andrew Morton192636a2006-12-22 01:11:30 -0800350static void __relay_reset(struct rchan_buf *buf, unsigned int init)
Jens Axboeb86ff9812006-03-23 19:56:55 +0100351{
352 size_t i;
353
354 if (init) {
355 init_waitqueue_head(&buf->read_wait);
356 kref_init(&buf->kref);
Peter Zijlstra26b56792016-10-11 13:54:33 -0700357 init_irq_work(&buf->wakeup_work, wakeup_readers);
358 } else {
359 irq_work_sync(&buf->wakeup_work);
360 }
Jens Axboeb86ff9812006-03-23 19:56:55 +0100361
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 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800383 * NOTE. Care should be taken that the channel isn't actually
Jens Axboeb86ff9812006-03-23 19:56:55 +0100384 * being used by anything when this call is made.
385 */
386void relay_reset(struct rchan *chan)
387{
Akash Goel017c59c2016-09-02 21:47:38 +0200388 struct rchan_buf *buf;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100389 unsigned int i;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100390
391 if (!chan)
392 return;
393
Akash Goel017c59c2016-09-02 21:47:38 +0200394 if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0))) {
395 __relay_reset(buf, 0);
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800396 return;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100397 }
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800398
399 mutex_lock(&relay_channels_mutex);
Lai Jiangshan98ba4032008-11-14 10:44:59 +0100400 for_each_possible_cpu(i)
Akash Goel017c59c2016-09-02 21:47:38 +0200401 if ((buf = *per_cpu_ptr(chan->buf, i)))
402 __relay_reset(buf, 0);
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800403 mutex_unlock(&relay_channels_mutex);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100404}
405EXPORT_SYMBOL_GPL(relay_reset);
406
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700407static inline void relay_set_buf_dentry(struct rchan_buf *buf,
408 struct dentry *dentry)
409{
410 buf->dentry = dentry;
David Howells7682c912015-03-17 22:26:16 +0000411 d_inode(buf->dentry)->i_size = buf->early_bytes;
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700412}
413
414static struct dentry *relay_create_buf_file(struct rchan *chan,
415 struct rchan_buf *buf,
416 unsigned int cpu)
417{
418 struct dentry *dentry;
419 char *tmpname;
420
421 tmpname = kzalloc(NAME_MAX + 1, GFP_KERNEL);
422 if (!tmpname)
423 return NULL;
424 snprintf(tmpname, NAME_MAX, "%s%d", chan->base_filename, cpu);
425
426 /* Create file in fs */
427 dentry = chan->cb->create_buf_file(tmpname, chan->parent,
428 S_IRUSR, buf,
429 &chan->is_global);
430
431 kfree(tmpname);
432
433 return dentry;
434}
435
Randy Dunlap4c78a662006-09-29 01:59:10 -0700436/*
Jens Axboeb86ff9812006-03-23 19:56:55 +0100437 * relay_open_buf - create a new relay channel buffer
438 *
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800439 * used by relay_open() and CPU hotplug.
Jens Axboeb86ff9812006-03-23 19:56:55 +0100440 */
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800441static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu)
Jens Axboeb86ff9812006-03-23 19:56:55 +0100442{
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800443 struct rchan_buf *buf = NULL;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100444 struct dentry *dentry;
445
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800446 if (chan->is_global)
Akash Goel017c59c2016-09-02 21:47:38 +0200447 return *per_cpu_ptr(chan->buf, 0);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100448
449 buf = relay_create_buf(chan);
450 if (!buf)
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700451 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);
Akash Goel59dbb2a2016-08-02 14:07:18 -0700458 } 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;
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700465 }
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800466
467 buf->cpu = cpu;
468 __relay_reset(buf, 1);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100469
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800470 if(chan->is_global) {
Akash Goel017c59c2016-09-02 21:47:38 +0200471 *per_cpu_ptr(chan->buf, 0) = buf;
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800472 buf->cpu = 0;
473 }
474
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700475 return buf;
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800476
477free_buf:
478 relay_destroy_buf(buf);
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700479 return NULL;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100480}
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 */
Andrew Morton192636a2006-12-22 01:11:30 -0800490static void relay_close_buf(struct rchan_buf *buf)
Jens Axboeb86ff9812006-03-23 19:56:55 +0100491{
492 buf->finalized = 1;
Peter Zijlstra26b56792016-10-11 13:54:33 -0700493 irq_work_sync(&buf->wakeup_work);
Dmitry Monakhovb8d4a5b2013-04-22 11:41:41 +0400494 buf->chan->cb->remove_buf_file(buf->dentry);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100495 kref_put(&buf->kref, relay_remove_buf);
496}
497
Andrew Morton192636a2006-12-22 01:11:30 -0800498static void setup_callbacks(struct rchan *chan,
Jens Axboeb86ff9812006-03-23 19:56:55 +0100499 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
Richard Weinbergere6d49892016-08-18 14:57:17 +0200519int relay_prepare_cpu(unsigned int cpu)
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800520{
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800521 struct rchan *chan;
Akash Goel017c59c2016-09-02 21:47:38 +0200522 struct rchan_buf *buf;
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800523
Richard Weinbergere6d49892016-08-18 14:57:17 +0200524 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;
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800533 }
Richard Weinbergere6d49892016-08-18 14:57:17 +0200534 *per_cpu_ptr(chan->buf, cpu) = buf;
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800535 }
Richard Weinbergere6d49892016-08-18 14:57:17 +0200536 mutex_unlock(&relay_channels_mutex);
537 return 0;
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800538}
539
540/**
Jens Axboeb86ff9812006-03-23 19:56:55 +0100541 * relay_open - create a new relay channel
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700542 * @base_filename: base name of files to create, %NULL for buffering only
543 * @parent: dentry of parent directory, %NULL for root directory or buffer
Jens Axboeb86ff9812006-03-23 19:56:55 +0100544 * @subbuf_size: size of sub-buffers
545 * @n_subbufs: number of sub-buffers
546 * @cb: client callback functions
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800547 * @private_data: user-defined data
Jens Axboeb86ff9812006-03-23 19:56:55 +0100548 *
Randy Dunlap4c78a662006-09-29 01:59:10 -0700549 * Returns channel pointer if successful, %NULL otherwise.
Jens Axboeb86ff9812006-03-23 19:56:55 +0100550 *
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
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800554 * permissions will be %S_IRUSR.
Akash Goel59dbb2a2016-08-02 14:07:18 -0700555 *
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.
Jens Axboeb86ff9812006-03-23 19:56:55 +0100559 */
560struct rchan *relay_open(const char *base_filename,
561 struct dentry *parent,
562 size_t subbuf_size,
563 size_t n_subbufs,
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800564 struct rchan_callbacks *cb,
565 void *private_data)
Jens Axboeb86ff9812006-03-23 19:56:55 +0100566{
567 unsigned int i;
568 struct rchan *chan;
Akash Goel017c59c2016-09-02 21:47:38 +0200569 struct rchan_buf *buf;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100570
571 if (!(subbuf_size && n_subbufs))
572 return NULL;
Dan Carpenterf6302f12012-02-10 09:03:58 +0100573 if (subbuf_size > UINT_MAX / n_subbufs)
574 return NULL;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100575
Robert P. J. Daycd861282006-12-13 00:34:52 -0800576 chan = kzalloc(sizeof(struct rchan), GFP_KERNEL);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100577 if (!chan)
578 return NULL;
579
Akash Goel017c59c2016-09-02 21:47:38 +0200580 chan->buf = alloc_percpu(struct rchan_buf *);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100581 chan->version = RELAYFS_CHANNEL_VERSION;
582 chan->n_subbufs = n_subbufs;
583 chan->subbuf_size = subbuf_size;
zhangwei(Jovi)a05342cb2013-04-30 15:28:41 -0700584 chan->alloc_size = PAGE_ALIGN(subbuf_size * n_subbufs);
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800585 chan->parent = parent;
586 chan->private_data = private_data;
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700587 if (base_filename) {
588 chan->has_base_filename = 1;
589 strlcpy(chan->base_filename, base_filename, NAME_MAX);
590 }
Jens Axboeb86ff9812006-03-23 19:56:55 +0100591 setup_callbacks(chan, cb);
592 kref_init(&chan->kref);
593
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800594 mutex_lock(&relay_channels_mutex);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100595 for_each_online_cpu(i) {
Akash Goel017c59c2016-09-02 21:47:38 +0200596 buf = relay_open_buf(chan, i);
597 if (!buf)
Jens Axboeb86ff9812006-03-23 19:56:55 +0100598 goto free_bufs;
Akash Goel017c59c2016-09-02 21:47:38 +0200599 *per_cpu_ptr(chan->buf, i) = buf;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100600 }
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800601 list_add(&chan->list, &relay_channels);
602 mutex_unlock(&relay_channels_mutex);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100603
Jens Axboeb86ff9812006-03-23 19:56:55 +0100604 return chan;
605
606free_bufs:
Lai Jiangshan98ba4032008-11-14 10:44:59 +0100607 for_each_possible_cpu(i) {
Akash Goel017c59c2016-09-02 21:47:38 +0200608 if ((buf = *per_cpu_ptr(chan->buf, i)))
609 relay_close_buf(buf);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100610 }
Jens Axboeb86ff9812006-03-23 19:56:55 +0100611
Jens Axboeb86ff9812006-03-23 19:56:55 +0100612 kref_put(&chan->kref, relay_destroy_channel);
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800613 mutex_unlock(&relay_channels_mutex);
Zhouyi Zhouba62baf2016-06-08 15:33:53 -0700614 kfree(chan);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100615 return NULL;
616}
617EXPORT_SYMBOL_GPL(relay_open);
618
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700619struct rchan_percpu_buf_dispatcher {
620 struct rchan_buf *buf;
621 struct dentry *dentry;
622};
623
624/* Called in atomic context. */
625static void __relay_set_buf_dentry(void *info)
626{
627 struct rchan_percpu_buf_dispatcher *p = info;
628
629 relay_set_buf_dentry(p->buf, p->dentry);
630}
631
632/**
633 * relay_late_setup_files - triggers file creation
634 * @chan: channel to operate on
635 * @base_filename: base name of files to create
636 * @parent: dentry of parent directory, %NULL for root directory
637 *
638 * Returns 0 if successful, non-zero otherwise.
639 *
Akash Goel59dbb2a2016-08-02 14:07:18 -0700640 * Use to setup files for a previously buffer-only channel created
641 * by relay_open() with a NULL parent dentry.
642 *
643 * For example, this is useful for perfomring early tracing in kernel,
644 * before VFS is up and then exposing the early results once the dentry
645 * is available.
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700646 */
647int relay_late_setup_files(struct rchan *chan,
648 const char *base_filename,
649 struct dentry *parent)
650{
651 int err = 0;
652 unsigned int i, curr_cpu;
653 unsigned long flags;
654 struct dentry *dentry;
Akash Goel017c59c2016-09-02 21:47:38 +0200655 struct rchan_buf *buf;
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700656 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? */
Jiri Slabyb786c6a2009-01-17 12:04:36 +0100665 if (unlikely(chan->has_base_filename)) {
666 mutex_unlock(&relay_channels_mutex);
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700667 return -EEXIST;
Jiri Slabyb786c6a2009-01-17 12:04:36 +0100668 }
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700669 chan->has_base_filename = 1;
670 chan->parent = parent;
Akash Goel59dbb2a2016-08-02 14:07:18 -0700671
672 if (chan->is_global) {
673 err = -EINVAL;
Akash Goel017c59c2016-09-02 21:47:38 +0200674 buf = *per_cpu_ptr(chan->buf, 0);
675 if (!WARN_ON_ONCE(!buf)) {
676 dentry = relay_create_buf_file(chan, buf, 0);
Akash Goel59dbb2a2016-08-02 14:07:18 -0700677 if (dentry && !WARN_ON_ONCE(!chan->is_global)) {
Akash Goel017c59c2016-09-02 21:47:38 +0200678 relay_set_buf_dentry(buf, dentry);
Akash Goel59dbb2a2016-08-02 14:07:18 -0700679 err = 0;
680 }
681 }
682 mutex_unlock(&relay_channels_mutex);
683 return err;
684 }
685
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700686 curr_cpu = get_cpu();
687 /*
688 * The CPU hotplug notifier ran before us and created buffers with
689 * no files associated. So it's safe to call relay_setup_buf_file()
690 * on all currently online CPUs.
691 */
692 for_each_online_cpu(i) {
Akash Goel017c59c2016-09-02 21:47:38 +0200693 buf = *per_cpu_ptr(chan->buf, i);
694 if (unlikely(!buf)) {
Ingo Molnar7a51cff2008-12-29 16:03:40 +0100695 WARN_ONCE(1, KERN_ERR "CPU has no buffer!\n");
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700696 err = -EINVAL;
697 break;
698 }
699
Akash Goel017c59c2016-09-02 21:47:38 +0200700 dentry = relay_create_buf_file(chan, buf, i);
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700701 if (unlikely(!dentry)) {
702 err = -EINVAL;
703 break;
704 }
705
706 if (curr_cpu == i) {
707 local_irq_save(flags);
Akash Goel017c59c2016-09-02 21:47:38 +0200708 relay_set_buf_dentry(buf, dentry);
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700709 local_irq_restore(flags);
710 } else {
Akash Goel017c59c2016-09-02 21:47:38 +0200711 disp.buf = buf;
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700712 disp.dentry = dentry;
713 smp_mb();
714 /* relay_channels_mutex must be held, so wait. */
715 err = smp_call_function_single(i,
716 __relay_set_buf_dentry,
717 &disp, 1);
718 }
719 if (unlikely(err))
720 break;
721 }
722 put_cpu();
723 mutex_unlock(&relay_channels_mutex);
724
725 return err;
726}
Akash Goel59dbb2a2016-08-02 14:07:18 -0700727EXPORT_SYMBOL_GPL(relay_late_setup_files);
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700728
Jens Axboeb86ff9812006-03-23 19:56:55 +0100729/**
730 * relay_switch_subbuf - switch to a new sub-buffer
731 * @buf: channel buffer
732 * @length: size of current event
733 *
734 * Returns either the length passed in or 0 if full.
735 *
736 * Performs sub-buffer-switch tasks such as invoking callbacks,
737 * updating padding counts, waking up readers, etc.
738 */
739size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length)
740{
741 void *old, *new;
742 size_t old_subbuf, new_subbuf;
743
744 if (unlikely(length > buf->chan->subbuf_size))
745 goto toobig;
746
747 if (buf->offset != buf->chan->subbuf_size + 1) {
748 buf->prev_padding = buf->chan->subbuf_size - buf->offset;
749 old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs;
750 buf->padding[old_subbuf] = buf->prev_padding;
751 buf->subbufs_produced++;
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700752 if (buf->dentry)
David Howells7682c912015-03-17 22:26:16 +0000753 d_inode(buf->dentry)->i_size +=
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700754 buf->chan->subbuf_size -
755 buf->padding[old_subbuf];
756 else
757 buf->early_bytes += buf->chan->subbuf_size -
758 buf->padding[old_subbuf];
Jens Axboe221415d2006-03-23 19:57:55 +0100759 smp_mb();
Peter Zijlstra26b56792016-10-11 13:54:33 -0700760 if (waitqueue_active(&buf->read_wait)) {
Tom Zanussi7c9cb382007-05-09 02:34:01 -0700761 /*
762 * Calling wake_up_interruptible() from here
763 * will deadlock if we happen to be logging
764 * from the scheduler (trying to re-grab
765 * rq->lock), so defer it.
766 */
Peter Zijlstra26b56792016-10-11 13:54:33 -0700767 irq_work_queue(&buf->wakeup_work);
768 }
Jens Axboeb86ff9812006-03-23 19:56:55 +0100769 }
770
771 old = buf->data;
772 new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs;
773 new = buf->start + new_subbuf * buf->chan->subbuf_size;
774 buf->offset = 0;
775 if (!buf->chan->cb->subbuf_start(buf, new, old, buf->prev_padding)) {
776 buf->offset = buf->chan->subbuf_size + 1;
777 return 0;
778 }
779 buf->data = new;
780 buf->padding[new_subbuf] = 0;
781
782 if (unlikely(length + buf->offset > buf->chan->subbuf_size))
783 goto toobig;
784
785 return length;
786
787toobig:
788 buf->chan->last_toobig = length;
789 return 0;
790}
791EXPORT_SYMBOL_GPL(relay_switch_subbuf);
792
793/**
794 * relay_subbufs_consumed - update the buffer's sub-buffers-consumed count
795 * @chan: the channel
796 * @cpu: the cpu associated with the channel buffer to update
797 * @subbufs_consumed: number of sub-buffers to add to current buf's count
798 *
799 * Adds to the channel buffer's consumed sub-buffer count.
800 * subbufs_consumed should be the number of sub-buffers newly consumed,
801 * not the total consumed.
802 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800803 * NOTE. Kernel clients don't need to call this function if the channel
Jens Axboeb86ff9812006-03-23 19:56:55 +0100804 * mode is 'overwrite'.
805 */
806void relay_subbufs_consumed(struct rchan *chan,
807 unsigned int cpu,
808 size_t subbufs_consumed)
809{
810 struct rchan_buf *buf;
811
Dan Carpenterc4c11b42016-12-14 15:05:38 -0800812 if (!chan || cpu >= NR_CPUS)
Jens Axboeb86ff9812006-03-23 19:56:55 +0100813 return;
814
Akash Goel017c59c2016-09-02 21:47:38 +0200815 buf = *per_cpu_ptr(chan->buf, cpu);
Dan Carpenterc4c11b42016-12-14 15:05:38 -0800816 if (!buf || subbufs_consumed > chan->n_subbufs)
Jens Axboeb86ff9812006-03-23 19:56:55 +0100817 return;
818
Aravind Srinivasan2c53d912009-04-02 16:58:59 -0700819 if (subbufs_consumed > buf->subbufs_produced - buf->subbufs_consumed)
Jens Axboeb86ff9812006-03-23 19:56:55 +0100820 buf->subbufs_consumed = buf->subbufs_produced;
Aravind Srinivasan2c53d912009-04-02 16:58:59 -0700821 else
822 buf->subbufs_consumed += subbufs_consumed;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100823}
824EXPORT_SYMBOL_GPL(relay_subbufs_consumed);
825
826/**
827 * relay_close - close the channel
828 * @chan: the channel
829 *
830 * Closes all channel buffers and frees the channel.
831 */
832void relay_close(struct rchan *chan)
833{
Akash Goel017c59c2016-09-02 21:47:38 +0200834 struct rchan_buf *buf;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100835 unsigned int i;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100836
837 if (!chan)
838 return;
839
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800840 mutex_lock(&relay_channels_mutex);
Akash Goel017c59c2016-09-02 21:47:38 +0200841 if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0)))
842 relay_close_buf(buf);
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800843 else
844 for_each_possible_cpu(i)
Akash Goel017c59c2016-09-02 21:47:38 +0200845 if ((buf = *per_cpu_ptr(chan->buf, i)))
846 relay_close_buf(buf);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100847
848 if (chan->last_toobig)
849 printk(KERN_WARNING "relay: one or more items not logged "
850 "[item size (%Zd) > sub-buffer size (%Zd)]\n",
851 chan->last_toobig, chan->subbuf_size);
852
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800853 list_del(&chan->list);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100854 kref_put(&chan->kref, relay_destroy_channel);
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800855 mutex_unlock(&relay_channels_mutex);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100856}
857EXPORT_SYMBOL_GPL(relay_close);
858
859/**
860 * relay_flush - close the channel
861 * @chan: the channel
862 *
Randy Dunlap4c78a662006-09-29 01:59:10 -0700863 * Flushes all channel buffers, i.e. forces buffer switch.
Jens Axboeb86ff9812006-03-23 19:56:55 +0100864 */
865void relay_flush(struct rchan *chan)
866{
Akash Goel017c59c2016-09-02 21:47:38 +0200867 struct rchan_buf *buf;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100868 unsigned int i;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100869
870 if (!chan)
871 return;
872
Akash Goel017c59c2016-09-02 21:47:38 +0200873 if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0))) {
874 relay_switch_subbuf(buf, 0);
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800875 return;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100876 }
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800877
878 mutex_lock(&relay_channels_mutex);
879 for_each_possible_cpu(i)
Akash Goel017c59c2016-09-02 21:47:38 +0200880 if ((buf = *per_cpu_ptr(chan->buf, i)))
881 relay_switch_subbuf(buf, 0);
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800882 mutex_unlock(&relay_channels_mutex);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100883}
884EXPORT_SYMBOL_GPL(relay_flush);
885
886/**
887 * relay_file_open - open file op for relay files
888 * @inode: the inode
889 * @filp: the file
890 *
891 * Increments the channel buffer refcount.
892 */
893static int relay_file_open(struct inode *inode, struct file *filp)
894{
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700895 struct rchan_buf *buf = inode->i_private;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100896 kref_get(&buf->kref);
897 filp->private_data = buf;
898
Lai Jiangshan37529fe2008-03-26 12:01:28 +0100899 return nonseekable_open(inode, filp);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100900}
901
902/**
903 * relay_file_mmap - mmap file op for relay files
904 * @filp: the file
905 * @vma: the vma describing what to map
906 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800907 * Calls upon relay_mmap_buf() to map the file into user space.
Jens Axboeb86ff9812006-03-23 19:56:55 +0100908 */
909static int relay_file_mmap(struct file *filp, struct vm_area_struct *vma)
910{
911 struct rchan_buf *buf = filp->private_data;
912 return relay_mmap_buf(buf, vma);
913}
914
915/**
916 * relay_file_poll - poll file op for relay files
917 * @filp: the file
918 * @wait: poll table
919 *
920 * Poll implemention.
921 */
922static unsigned int relay_file_poll(struct file *filp, poll_table *wait)
923{
924 unsigned int mask = 0;
925 struct rchan_buf *buf = filp->private_data;
926
927 if (buf->finalized)
928 return POLLERR;
929
930 if (filp->f_mode & FMODE_READ) {
931 poll_wait(filp, &buf->read_wait, wait);
932 if (!relay_buf_empty(buf))
933 mask |= POLLIN | POLLRDNORM;
934 }
935
936 return mask;
937}
938
939/**
940 * relay_file_release - release file op for relay files
941 * @inode: the inode
942 * @filp: the file
943 *
944 * Decrements the channel refcount, as the filesystem is
945 * no longer using it.
946 */
947static int relay_file_release(struct inode *inode, struct file *filp)
948{
949 struct rchan_buf *buf = filp->private_data;
950 kref_put(&buf->kref, relay_remove_buf);
951
952 return 0;
953}
954
Randy Dunlap4c78a662006-09-29 01:59:10 -0700955/*
Jens Axboeb86ff9812006-03-23 19:56:55 +0100956 * relay_file_read_consume - update the consumed count for the buffer
957 */
958static void relay_file_read_consume(struct rchan_buf *buf,
959 size_t read_pos,
960 size_t bytes_consumed)
961{
962 size_t subbuf_size = buf->chan->subbuf_size;
963 size_t n_subbufs = buf->chan->n_subbufs;
964 size_t read_subbuf;
965
Tom Zanussi32194452008-08-05 13:01:10 -0700966 if (buf->subbufs_produced == buf->subbufs_consumed &&
967 buf->offset == buf->bytes_consumed)
968 return;
969
Jens Axboeb86ff9812006-03-23 19:56:55 +0100970 if (buf->bytes_consumed + bytes_consumed > subbuf_size) {
971 relay_subbufs_consumed(buf->chan, buf->cpu, 1);
972 buf->bytes_consumed = 0;
973 }
974
975 buf->bytes_consumed += bytes_consumed;
Masami Hiramatsua66e3562007-06-27 14:10:04 -0700976 if (!read_pos)
977 read_subbuf = buf->subbufs_consumed % n_subbufs;
978 else
979 read_subbuf = read_pos / buf->chan->subbuf_size;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100980 if (buf->bytes_consumed + buf->padding[read_subbuf] == subbuf_size) {
981 if ((read_subbuf == buf->subbufs_produced % n_subbufs) &&
982 (buf->offset == subbuf_size))
983 return;
984 relay_subbufs_consumed(buf->chan, buf->cpu, 1);
985 buf->bytes_consumed = 0;
986 }
987}
988
Randy Dunlap4c78a662006-09-29 01:59:10 -0700989/*
Jens Axboeb86ff9812006-03-23 19:56:55 +0100990 * relay_file_read_avail - boolean, are there unconsumed bytes available?
991 */
992static int relay_file_read_avail(struct rchan_buf *buf, size_t read_pos)
993{
Jens Axboeb86ff9812006-03-23 19:56:55 +0100994 size_t subbuf_size = buf->chan->subbuf_size;
995 size_t n_subbufs = buf->chan->n_subbufs;
Jens Axboe221415d2006-03-23 19:57:55 +0100996 size_t produced = buf->subbufs_produced;
997 size_t consumed = buf->subbufs_consumed;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100998
999 relay_file_read_consume(buf, read_pos, 0);
1000
Tom Zanussi32194452008-08-05 13:01:10 -07001001 consumed = buf->subbufs_consumed;
1002
Jens Axboe221415d2006-03-23 19:57:55 +01001003 if (unlikely(buf->offset > subbuf_size)) {
1004 if (produced == consumed)
1005 return 0;
1006 return 1;
1007 }
1008
1009 if (unlikely(produced - consumed >= n_subbufs)) {
Masami Hiramatsua66e3562007-06-27 14:10:04 -07001010 consumed = produced - n_subbufs + 1;
Jens Axboe221415d2006-03-23 19:57:55 +01001011 buf->subbufs_consumed = consumed;
Masami Hiramatsua66e3562007-06-27 14:10:04 -07001012 buf->bytes_consumed = 0;
Jens Axboe221415d2006-03-23 19:57:55 +01001013 }
Daniel Walker1bfbc602007-10-18 03:06:05 -07001014
Jens Axboe221415d2006-03-23 19:57:55 +01001015 produced = (produced % n_subbufs) * subbuf_size + buf->offset;
1016 consumed = (consumed % n_subbufs) * subbuf_size + buf->bytes_consumed;
1017
1018 if (consumed > produced)
1019 produced += n_subbufs * subbuf_size;
Daniel Walker1bfbc602007-10-18 03:06:05 -07001020
Tom Zanussi32194452008-08-05 13:01:10 -07001021 if (consumed == produced) {
1022 if (buf->offset == subbuf_size &&
1023 buf->subbufs_produced > buf->subbufs_consumed)
1024 return 1;
Jens Axboe221415d2006-03-23 19:57:55 +01001025 return 0;
Tom Zanussi32194452008-08-05 13:01:10 -07001026 }
Jens Axboe221415d2006-03-23 19:57:55 +01001027
Jens Axboeb86ff9812006-03-23 19:56:55 +01001028 return 1;
1029}
1030
1031/**
1032 * relay_file_read_subbuf_avail - return bytes available in sub-buffer
Randy Dunlap4c78a662006-09-29 01:59:10 -07001033 * @read_pos: file read position
1034 * @buf: relay channel buffer
Jens Axboeb86ff9812006-03-23 19:56:55 +01001035 */
1036static size_t relay_file_read_subbuf_avail(size_t read_pos,
1037 struct rchan_buf *buf)
1038{
1039 size_t padding, avail = 0;
1040 size_t read_subbuf, read_offset, write_subbuf, write_offset;
1041 size_t subbuf_size = buf->chan->subbuf_size;
1042
1043 write_subbuf = (buf->data - buf->start) / subbuf_size;
1044 write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset;
1045 read_subbuf = read_pos / subbuf_size;
1046 read_offset = read_pos % subbuf_size;
1047 padding = buf->padding[read_subbuf];
1048
1049 if (read_subbuf == write_subbuf) {
1050 if (read_offset + padding < write_offset)
1051 avail = write_offset - (read_offset + padding);
1052 } else
1053 avail = (subbuf_size - padding) - read_offset;
1054
1055 return avail;
1056}
1057
1058/**
1059 * relay_file_read_start_pos - find the first available byte to read
Randy Dunlap4c78a662006-09-29 01:59:10 -07001060 * @read_pos: file read position
1061 * @buf: relay channel buffer
Jens Axboeb86ff9812006-03-23 19:56:55 +01001062 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -08001063 * If the @read_pos is in the middle of padding, return the
Jens Axboeb86ff9812006-03-23 19:56:55 +01001064 * position of the first actually available byte, otherwise
1065 * return the original value.
1066 */
1067static size_t relay_file_read_start_pos(size_t read_pos,
1068 struct rchan_buf *buf)
1069{
1070 size_t read_subbuf, padding, padding_start, padding_end;
1071 size_t subbuf_size = buf->chan->subbuf_size;
1072 size_t n_subbufs = buf->chan->n_subbufs;
David Wilder8d62fde2007-06-27 14:10:03 -07001073 size_t consumed = buf->subbufs_consumed % n_subbufs;
Jens Axboeb86ff9812006-03-23 19:56:55 +01001074
David Wilder8d62fde2007-06-27 14:10:03 -07001075 if (!read_pos)
1076 read_pos = consumed * subbuf_size + buf->bytes_consumed;
Jens Axboeb86ff9812006-03-23 19:56:55 +01001077 read_subbuf = read_pos / subbuf_size;
1078 padding = buf->padding[read_subbuf];
1079 padding_start = (read_subbuf + 1) * subbuf_size - padding;
1080 padding_end = (read_subbuf + 1) * subbuf_size;
1081 if (read_pos >= padding_start && read_pos < padding_end) {
1082 read_subbuf = (read_subbuf + 1) % n_subbufs;
1083 read_pos = read_subbuf * subbuf_size;
1084 }
1085
1086 return read_pos;
1087}
1088
1089/**
1090 * relay_file_read_end_pos - return the new read position
Randy Dunlap4c78a662006-09-29 01:59:10 -07001091 * @read_pos: file read position
1092 * @buf: relay channel buffer
1093 * @count: number of bytes to be read
Jens Axboeb86ff9812006-03-23 19:56:55 +01001094 */
1095static size_t relay_file_read_end_pos(struct rchan_buf *buf,
1096 size_t read_pos,
1097 size_t count)
1098{
1099 size_t read_subbuf, padding, end_pos;
1100 size_t subbuf_size = buf->chan->subbuf_size;
1101 size_t n_subbufs = buf->chan->n_subbufs;
1102
1103 read_subbuf = read_pos / subbuf_size;
1104 padding = buf->padding[read_subbuf];
1105 if (read_pos % subbuf_size + count + padding == subbuf_size)
1106 end_pos = (read_subbuf + 1) * subbuf_size;
1107 else
1108 end_pos = read_pos + count;
1109 if (end_pos >= subbuf_size * n_subbufs)
1110 end_pos = 0;
1111
1112 return end_pos;
1113}
1114
Al Viroa7c22422016-09-25 22:52:02 -04001115static ssize_t relay_file_read(struct file *filp,
1116 char __user *buffer,
1117 size_t count,
1118 loff_t *ppos)
Tom Zanussi6dac40a2006-03-23 19:58:45 +01001119{
1120 struct rchan_buf *buf = filp->private_data;
1121 size_t read_start, avail;
Al Viroa7c22422016-09-25 22:52:02 -04001122 size_t written = 0;
Tom Zanussi6dac40a2006-03-23 19:58:45 +01001123 int ret;
1124
Al Viroa7c22422016-09-25 22:52:02 -04001125 if (!count)
Jens Axboe221415d2006-03-23 19:57:55 +01001126 return 0;
1127
Al Viro59551022016-01-22 15:40:57 -05001128 inode_lock(file_inode(filp));
Tom Zanussi6dac40a2006-03-23 19:58:45 +01001129 do {
Al Viroa7c22422016-09-25 22:52:02 -04001130 void *from;
1131
Tom Zanussi6dac40a2006-03-23 19:58:45 +01001132 if (!relay_file_read_avail(buf, *ppos))
Jens Axboe221415d2006-03-23 19:57:55 +01001133 break;
Tom Zanussi6dac40a2006-03-23 19:58:45 +01001134
1135 read_start = relay_file_read_start_pos(*ppos, buf);
1136 avail = relay_file_read_subbuf_avail(read_start, buf);
1137 if (!avail)
1138 break;
1139
Al Viroa7c22422016-09-25 22:52:02 -04001140 avail = min(count, avail);
1141 from = buf->start + read_start;
1142 ret = avail;
1143 if (copy_to_user(buffer, from, avail))
Tom Zanussi6dac40a2006-03-23 19:58:45 +01001144 break;
1145
Al Viroa7c22422016-09-25 22:52:02 -04001146 buffer += ret;
1147 written += ret;
1148 count -= ret;
1149
1150 relay_file_read_consume(buf, read_start, ret);
1151 *ppos = relay_file_read_end_pos(buf, read_start, ret);
1152 } while (count);
Al Viro59551022016-01-22 15:40:57 -05001153 inode_unlock(file_inode(filp));
Jens Axboe221415d2006-03-23 19:57:55 +01001154
Al Viroa7c22422016-09-25 22:52:02 -04001155 return written;
Tom Zanussi6dac40a2006-03-23 19:58:45 +01001156}
1157
Jens Axboe1db60cf2007-06-12 08:43:46 +02001158static void relay_consume_bytes(struct rchan_buf *rbuf, int bytes_consumed)
1159{
1160 rbuf->bytes_consumed += bytes_consumed;
1161
1162 if (rbuf->bytes_consumed >= rbuf->chan->subbuf_size) {
1163 relay_subbufs_consumed(rbuf->chan, rbuf->cpu, 1);
1164 rbuf->bytes_consumed %= rbuf->chan->subbuf_size;
1165 }
1166}
1167
Tom Zanussiebf99092007-06-04 09:12:05 +02001168static void relay_pipe_buf_release(struct pipe_inode_info *pipe,
1169 struct pipe_buffer *buf)
Jens Axboe221415d2006-03-23 19:57:55 +01001170{
Tom Zanussiebf99092007-06-04 09:12:05 +02001171 struct rchan_buf *rbuf;
1172
1173 rbuf = (struct rchan_buf *)page_private(buf->page);
Jens Axboe1db60cf2007-06-12 08:43:46 +02001174 relay_consume_bytes(rbuf, buf->private);
Tom Zanussiebf99092007-06-04 09:12:05 +02001175}
1176
Alexey Dobriyan28dfef82009-12-15 16:46:48 -08001177static const struct pipe_buf_operations relay_pipe_buf_ops = {
Tom Zanussiebf99092007-06-04 09:12:05 +02001178 .can_merge = 0,
Jens Axboecac36bb02007-06-14 13:10:48 +02001179 .confirm = generic_pipe_buf_confirm,
Tom Zanussiebf99092007-06-04 09:12:05 +02001180 .release = relay_pipe_buf_release,
1181 .steal = generic_pipe_buf_steal,
1182 .get = generic_pipe_buf_get,
1183};
1184
Jens Axboe5eb7f9f2008-03-26 12:04:09 +01001185static void relay_page_release(struct splice_pipe_desc *spd, unsigned int i)
1186{
1187}
1188
Tom Zanussid3f35d92007-07-12 08:12:05 +02001189/*
Tom Zanussiebf99092007-06-04 09:12:05 +02001190 * subbuf_splice_actor - splice up to one subbuf's worth of data
1191 */
Dan Carpenter5f1664f2010-03-05 13:42:51 -08001192static ssize_t subbuf_splice_actor(struct file *in,
Tom Zanussiebf99092007-06-04 09:12:05 +02001193 loff_t *ppos,
1194 struct pipe_inode_info *pipe,
1195 size_t len,
1196 unsigned int flags,
1197 int *nonpad_ret)
1198{
Dan Carpenter5f1664f2010-03-05 13:42:51 -08001199 unsigned int pidx, poff, total_len, subbuf_pages, nr_pages;
Tom Zanussiebf99092007-06-04 09:12:05 +02001200 struct rchan_buf *rbuf = in->private_data;
1201 unsigned int subbuf_size = rbuf->chan->subbuf_size;
Tom Zanussi24da24d2007-07-12 08:12:04 +02001202 uint64_t pos = (uint64_t) *ppos;
1203 uint32_t alloc_size = (uint32_t) rbuf->chan->alloc_size;
1204 size_t read_start = (size_t) do_div(pos, alloc_size);
Tom Zanussiebf99092007-06-04 09:12:05 +02001205 size_t read_subbuf = read_start / subbuf_size;
1206 size_t padding = rbuf->padding[read_subbuf];
1207 size_t nonpad_end = read_subbuf * subbuf_size + subbuf_size - padding;
Jens Axboe35f3d142010-05-20 10:43:18 +02001208 struct page *pages[PIPE_DEF_BUFFERS];
1209 struct partial_page partial[PIPE_DEF_BUFFERS];
Jens Axboe1db60cf2007-06-12 08:43:46 +02001210 struct splice_pipe_desc spd = {
1211 .pages = pages,
1212 .nr_pages = 0,
Eric Dumazet047fe362012-06-12 15:24:40 +02001213 .nr_pages_max = PIPE_DEF_BUFFERS,
Jens Axboe1db60cf2007-06-12 08:43:46 +02001214 .partial = partial,
1215 .flags = flags,
1216 .ops = &relay_pipe_buf_ops,
Jens Axboe5eb7f9f2008-03-26 12:04:09 +01001217 .spd_release = relay_page_release,
Jens Axboe1db60cf2007-06-12 08:43:46 +02001218 };
Dan Carpenter5f1664f2010-03-05 13:42:51 -08001219 ssize_t ret;
Tom Zanussiebf99092007-06-04 09:12:05 +02001220
1221 if (rbuf->subbufs_produced == rbuf->subbufs_consumed)
1222 return 0;
Jens Axboe35f3d142010-05-20 10:43:18 +02001223 if (splice_grow_spd(pipe, &spd))
1224 return -ENOMEM;
Tom Zanussiebf99092007-06-04 09:12:05 +02001225
Jens Axboe1db60cf2007-06-12 08:43:46 +02001226 /*
1227 * Adjust read len, if longer than what is available
1228 */
1229 if (len > (subbuf_size - read_start % subbuf_size))
1230 len = subbuf_size - read_start % subbuf_size;
Tom Zanussiebf99092007-06-04 09:12:05 +02001231
1232 subbuf_pages = rbuf->chan->alloc_size >> PAGE_SHIFT;
1233 pidx = (read_start / PAGE_SIZE) % subbuf_pages;
1234 poff = read_start & ~PAGE_MASK;
Al Viroa786c062014-04-11 12:01:03 -04001235 nr_pages = min_t(unsigned int, subbuf_pages, spd.nr_pages_max);
Tom Zanussiebf99092007-06-04 09:12:05 +02001236
Jens Axboe16d54662008-03-17 09:04:59 +01001237 for (total_len = 0; spd.nr_pages < nr_pages; spd.nr_pages++) {
Jens Axboe1db60cf2007-06-12 08:43:46 +02001238 unsigned int this_len, this_end, private;
1239 unsigned int cur_pos = read_start + total_len;
Tom Zanussiebf99092007-06-04 09:12:05 +02001240
Jens Axboe1db60cf2007-06-12 08:43:46 +02001241 if (!len)
1242 break;
1243
1244 this_len = min_t(unsigned long, len, PAGE_SIZE - poff);
1245 private = this_len;
1246
1247 spd.pages[spd.nr_pages] = rbuf->page_array[pidx];
1248 spd.partial[spd.nr_pages].offset = poff;
1249
1250 this_end = cur_pos + this_len;
1251 if (this_end >= nonpad_end) {
1252 this_len = nonpad_end - cur_pos;
1253 private = this_len + padding;
1254 }
1255 spd.partial[spd.nr_pages].len = this_len;
1256 spd.partial[spd.nr_pages].private = private;
1257
1258 len -= this_len;
1259 total_len += this_len;
1260 poff = 0;
1261 pidx = (pidx + 1) % subbuf_pages;
1262
1263 if (this_end >= nonpad_end) {
1264 spd.nr_pages++;
Tom Zanussiebf99092007-06-04 09:12:05 +02001265 break;
1266 }
Tom Zanussiebf99092007-06-04 09:12:05 +02001267 }
1268
Jens Axboe35f3d142010-05-20 10:43:18 +02001269 ret = 0;
Jens Axboe1db60cf2007-06-12 08:43:46 +02001270 if (!spd.nr_pages)
Jens Axboe35f3d142010-05-20 10:43:18 +02001271 goto out;
Tom Zanussiebf99092007-06-04 09:12:05 +02001272
Jens Axboe1db60cf2007-06-12 08:43:46 +02001273 ret = *nonpad_ret = splice_to_pipe(pipe, &spd);
1274 if (ret < 0 || ret < total_len)
Jens Axboe35f3d142010-05-20 10:43:18 +02001275 goto out;
Tom Zanussiebf99092007-06-04 09:12:05 +02001276
Jens Axboe1db60cf2007-06-12 08:43:46 +02001277 if (read_start + ret == nonpad_end)
1278 ret += padding;
1279
Jens Axboe35f3d142010-05-20 10:43:18 +02001280out:
Eric Dumazet047fe362012-06-12 15:24:40 +02001281 splice_shrink_spd(&spd);
1282 return ret;
Tom Zanussiebf99092007-06-04 09:12:05 +02001283}
1284
1285static ssize_t relay_file_splice_read(struct file *in,
1286 loff_t *ppos,
1287 struct pipe_inode_info *pipe,
1288 size_t len,
1289 unsigned int flags)
1290{
1291 ssize_t spliced;
1292 int ret;
1293 int nonpad_ret = 0;
1294
1295 ret = 0;
1296 spliced = 0;
1297
Tom Zanussia82c53a2008-05-09 13:28:36 +02001298 while (len && !spliced) {
Tom Zanussiebf99092007-06-04 09:12:05 +02001299 ret = subbuf_splice_actor(in, ppos, pipe, len, flags, &nonpad_ret);
1300 if (ret < 0)
1301 break;
1302 else if (!ret) {
Tom Zanussifbb5b7a2008-12-09 13:14:10 -08001303 if (flags & SPLICE_F_NONBLOCK)
Tom Zanussiebf99092007-06-04 09:12:05 +02001304 ret = -EAGAIN;
Tom Zanussifbb5b7a2008-12-09 13:14:10 -08001305 break;
Tom Zanussiebf99092007-06-04 09:12:05 +02001306 }
1307
1308 *ppos += ret;
1309 if (ret > len)
1310 len = 0;
1311 else
1312 len -= ret;
1313 spliced += nonpad_ret;
1314 nonpad_ret = 0;
1315 }
1316
1317 if (spliced)
1318 return spliced;
1319
1320 return ret;
Jens Axboe221415d2006-03-23 19:57:55 +01001321}
1322
Helge Deller15ad7cd2006-12-06 20:40:36 -08001323const struct file_operations relay_file_operations = {
Jens Axboeb86ff9812006-03-23 19:56:55 +01001324 .open = relay_file_open,
1325 .poll = relay_file_poll,
1326 .mmap = relay_file_mmap,
1327 .read = relay_file_read,
1328 .llseek = no_llseek,
1329 .release = relay_file_release,
Tom Zanussiebf99092007-06-04 09:12:05 +02001330 .splice_read = relay_file_splice_read,
Jens Axboeb86ff9812006-03-23 19:56:55 +01001331};
1332EXPORT_SYMBOL_GPL(relay_file_operations);