blob: c3029402f15c3367bdd3d59210eee471b6bb41c0 [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 */
Dave Jiang11bac802017-02-24 14:56:41 -080042static int relay_buf_fault(struct vm_fault *vmf)
Jens Axboeb86ff9812006-03-23 19:56:55 +010043{
44 struct page *page;
Dave Jiang11bac802017-02-24 14:56:41 -080045 struct rchan_buf *buf = vmf->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 Dobriyanf0f37e2f2009-09-27 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 Virof4ae40a62011-07-24 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);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100614 return NULL;
615}
616EXPORT_SYMBOL_GPL(relay_open);
617
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700618struct rchan_percpu_buf_dispatcher {
619 struct rchan_buf *buf;
620 struct dentry *dentry;
621};
622
623/* Called in atomic context. */
624static void __relay_set_buf_dentry(void *info)
625{
626 struct rchan_percpu_buf_dispatcher *p = info;
627
628 relay_set_buf_dentry(p->buf, p->dentry);
629}
630
631/**
632 * relay_late_setup_files - triggers file creation
633 * @chan: channel to operate on
634 * @base_filename: base name of files to create
635 * @parent: dentry of parent directory, %NULL for root directory
636 *
637 * Returns 0 if successful, non-zero otherwise.
638 *
Akash Goel59dbb2a2016-08-02 14:07:18 -0700639 * Use to setup files for a previously buffer-only channel created
640 * by relay_open() with a NULL parent dentry.
641 *
642 * For example, this is useful for perfomring early tracing in kernel,
643 * before VFS is up and then exposing the early results once the dentry
644 * is available.
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700645 */
646int relay_late_setup_files(struct rchan *chan,
647 const char *base_filename,
648 struct dentry *parent)
649{
650 int err = 0;
651 unsigned int i, curr_cpu;
652 unsigned long flags;
653 struct dentry *dentry;
Akash Goel017c59c2016-09-02 21:47:38 +0200654 struct rchan_buf *buf;
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700655 struct rchan_percpu_buf_dispatcher disp;
656
657 if (!chan || !base_filename)
658 return -EINVAL;
659
660 strlcpy(chan->base_filename, base_filename, NAME_MAX);
661
662 mutex_lock(&relay_channels_mutex);
663 /* Is chan already set up? */
Jiri Slabyb786c6a2009-01-17 12:04:36 +0100664 if (unlikely(chan->has_base_filename)) {
665 mutex_unlock(&relay_channels_mutex);
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700666 return -EEXIST;
Jiri Slabyb786c6a2009-01-17 12:04:36 +0100667 }
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700668 chan->has_base_filename = 1;
669 chan->parent = parent;
Akash Goel59dbb2a2016-08-02 14:07:18 -0700670
671 if (chan->is_global) {
672 err = -EINVAL;
Akash Goel017c59c2016-09-02 21:47:38 +0200673 buf = *per_cpu_ptr(chan->buf, 0);
674 if (!WARN_ON_ONCE(!buf)) {
675 dentry = relay_create_buf_file(chan, buf, 0);
Akash Goel59dbb2a2016-08-02 14:07:18 -0700676 if (dentry && !WARN_ON_ONCE(!chan->is_global)) {
Akash Goel017c59c2016-09-02 21:47:38 +0200677 relay_set_buf_dentry(buf, dentry);
Akash Goel59dbb2a2016-08-02 14:07:18 -0700678 err = 0;
679 }
680 }
681 mutex_unlock(&relay_channels_mutex);
682 return err;
683 }
684
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700685 curr_cpu = get_cpu();
686 /*
687 * The CPU hotplug notifier ran before us and created buffers with
688 * no files associated. So it's safe to call relay_setup_buf_file()
689 * on all currently online CPUs.
690 */
691 for_each_online_cpu(i) {
Akash Goel017c59c2016-09-02 21:47:38 +0200692 buf = *per_cpu_ptr(chan->buf, i);
693 if (unlikely(!buf)) {
Ingo Molnar7a51cff2008-12-29 16:03:40 +0100694 WARN_ONCE(1, KERN_ERR "CPU has no buffer!\n");
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700695 err = -EINVAL;
696 break;
697 }
698
Akash Goel017c59c2016-09-02 21:47:38 +0200699 dentry = relay_create_buf_file(chan, buf, i);
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700700 if (unlikely(!dentry)) {
701 err = -EINVAL;
702 break;
703 }
704
705 if (curr_cpu == i) {
706 local_irq_save(flags);
Akash Goel017c59c2016-09-02 21:47:38 +0200707 relay_set_buf_dentry(buf, dentry);
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700708 local_irq_restore(flags);
709 } else {
Akash Goel017c59c2016-09-02 21:47:38 +0200710 disp.buf = buf;
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700711 disp.dentry = dentry;
712 smp_mb();
713 /* relay_channels_mutex must be held, so wait. */
714 err = smp_call_function_single(i,
715 __relay_set_buf_dentry,
716 &disp, 1);
717 }
718 if (unlikely(err))
719 break;
720 }
721 put_cpu();
722 mutex_unlock(&relay_channels_mutex);
723
724 return err;
725}
Akash Goel59dbb2a2016-08-02 14:07:18 -0700726EXPORT_SYMBOL_GPL(relay_late_setup_files);
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700727
Jens Axboeb86ff9812006-03-23 19:56:55 +0100728/**
729 * relay_switch_subbuf - switch to a new sub-buffer
730 * @buf: channel buffer
731 * @length: size of current event
732 *
733 * Returns either the length passed in or 0 if full.
734 *
735 * Performs sub-buffer-switch tasks such as invoking callbacks,
736 * updating padding counts, waking up readers, etc.
737 */
738size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length)
739{
740 void *old, *new;
741 size_t old_subbuf, new_subbuf;
742
743 if (unlikely(length > buf->chan->subbuf_size))
744 goto toobig;
745
746 if (buf->offset != buf->chan->subbuf_size + 1) {
747 buf->prev_padding = buf->chan->subbuf_size - buf->offset;
748 old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs;
749 buf->padding[old_subbuf] = buf->prev_padding;
750 buf->subbufs_produced++;
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700751 if (buf->dentry)
David Howells7682c912015-03-17 22:26:16 +0000752 d_inode(buf->dentry)->i_size +=
Eduard - Gabriel Munteanu20d8b672008-07-25 19:45:12 -0700753 buf->chan->subbuf_size -
754 buf->padding[old_subbuf];
755 else
756 buf->early_bytes += buf->chan->subbuf_size -
757 buf->padding[old_subbuf];
Jens Axboe221415d2006-03-23 19:57:55 +0100758 smp_mb();
Peter Zijlstra26b56792016-10-11 13:54:33 -0700759 if (waitqueue_active(&buf->read_wait)) {
Tom Zanussi7c9cb382007-05-09 02:34:01 -0700760 /*
761 * Calling wake_up_interruptible() from here
762 * will deadlock if we happen to be logging
763 * from the scheduler (trying to re-grab
764 * rq->lock), so defer it.
765 */
Peter Zijlstra26b56792016-10-11 13:54:33 -0700766 irq_work_queue(&buf->wakeup_work);
767 }
Jens Axboeb86ff9812006-03-23 19:56:55 +0100768 }
769
770 old = buf->data;
771 new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs;
772 new = buf->start + new_subbuf * buf->chan->subbuf_size;
773 buf->offset = 0;
774 if (!buf->chan->cb->subbuf_start(buf, new, old, buf->prev_padding)) {
775 buf->offset = buf->chan->subbuf_size + 1;
776 return 0;
777 }
778 buf->data = new;
779 buf->padding[new_subbuf] = 0;
780
781 if (unlikely(length + buf->offset > buf->chan->subbuf_size))
782 goto toobig;
783
784 return length;
785
786toobig:
787 buf->chan->last_toobig = length;
788 return 0;
789}
790EXPORT_SYMBOL_GPL(relay_switch_subbuf);
791
792/**
793 * relay_subbufs_consumed - update the buffer's sub-buffers-consumed count
794 * @chan: the channel
795 * @cpu: the cpu associated with the channel buffer to update
796 * @subbufs_consumed: number of sub-buffers to add to current buf's count
797 *
798 * Adds to the channel buffer's consumed sub-buffer count.
799 * subbufs_consumed should be the number of sub-buffers newly consumed,
800 * not the total consumed.
801 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800802 * NOTE. Kernel clients don't need to call this function if the channel
Jens Axboeb86ff9812006-03-23 19:56:55 +0100803 * mode is 'overwrite'.
804 */
805void relay_subbufs_consumed(struct rchan *chan,
806 unsigned int cpu,
807 size_t subbufs_consumed)
808{
809 struct rchan_buf *buf;
810
Dan Carpenter9a29d0f2016-12-14 15:05:38 -0800811 if (!chan || cpu >= NR_CPUS)
Jens Axboeb86ff9812006-03-23 19:56:55 +0100812 return;
813
Akash Goel017c59c2016-09-02 21:47:38 +0200814 buf = *per_cpu_ptr(chan->buf, cpu);
Dan Carpenter9a29d0f2016-12-14 15:05:38 -0800815 if (!buf || subbufs_consumed > chan->n_subbufs)
Jens Axboeb86ff9812006-03-23 19:56:55 +0100816 return;
817
Aravind Srinivasan2c53d912009-04-02 16:58:59 -0700818 if (subbufs_consumed > buf->subbufs_produced - buf->subbufs_consumed)
Jens Axboeb86ff9812006-03-23 19:56:55 +0100819 buf->subbufs_consumed = buf->subbufs_produced;
Aravind Srinivasan2c53d912009-04-02 16:58:59 -0700820 else
821 buf->subbufs_consumed += subbufs_consumed;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100822}
823EXPORT_SYMBOL_GPL(relay_subbufs_consumed);
824
825/**
826 * relay_close - close the channel
827 * @chan: the channel
828 *
829 * Closes all channel buffers and frees the channel.
830 */
831void relay_close(struct rchan *chan)
832{
Akash Goel017c59c2016-09-02 21:47:38 +0200833 struct rchan_buf *buf;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100834 unsigned int i;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100835
836 if (!chan)
837 return;
838
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800839 mutex_lock(&relay_channels_mutex);
Akash Goel017c59c2016-09-02 21:47:38 +0200840 if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0)))
841 relay_close_buf(buf);
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800842 else
843 for_each_possible_cpu(i)
Akash Goel017c59c2016-09-02 21:47:38 +0200844 if ((buf = *per_cpu_ptr(chan->buf, i)))
845 relay_close_buf(buf);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100846
847 if (chan->last_toobig)
848 printk(KERN_WARNING "relay: one or more items not logged "
Alexey Dobriyan5b5e0922017-02-27 14:30:02 -0800849 "[item size (%zd) > sub-buffer size (%zd)]\n",
Jens Axboeb86ff9812006-03-23 19:56:55 +0100850 chan->last_toobig, chan->subbuf_size);
851
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800852 list_del(&chan->list);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100853 kref_put(&chan->kref, relay_destroy_channel);
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800854 mutex_unlock(&relay_channels_mutex);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100855}
856EXPORT_SYMBOL_GPL(relay_close);
857
858/**
859 * relay_flush - close the channel
860 * @chan: the channel
861 *
Randy Dunlap4c78a662006-09-29 01:59:10 -0700862 * Flushes all channel buffers, i.e. forces buffer switch.
Jens Axboeb86ff9812006-03-23 19:56:55 +0100863 */
864void relay_flush(struct rchan *chan)
865{
Akash Goel017c59c2016-09-02 21:47:38 +0200866 struct rchan_buf *buf;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100867 unsigned int i;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100868
869 if (!chan)
870 return;
871
Akash Goel017c59c2016-09-02 21:47:38 +0200872 if (chan->is_global && (buf = *per_cpu_ptr(chan->buf, 0))) {
873 relay_switch_subbuf(buf, 0);
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800874 return;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100875 }
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800876
877 mutex_lock(&relay_channels_mutex);
878 for_each_possible_cpu(i)
Akash Goel017c59c2016-09-02 21:47:38 +0200879 if ((buf = *per_cpu_ptr(chan->buf, i)))
880 relay_switch_subbuf(buf, 0);
Mathieu Desnoyers23c88752007-02-10 01:45:05 -0800881 mutex_unlock(&relay_channels_mutex);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100882}
883EXPORT_SYMBOL_GPL(relay_flush);
884
885/**
886 * relay_file_open - open file op for relay files
887 * @inode: the inode
888 * @filp: the file
889 *
890 * Increments the channel buffer refcount.
891 */
892static int relay_file_open(struct inode *inode, struct file *filp)
893{
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700894 struct rchan_buf *buf = inode->i_private;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100895 kref_get(&buf->kref);
896 filp->private_data = buf;
897
Lai Jiangshan37529fe2008-03-26 12:01:28 +0100898 return nonseekable_open(inode, filp);
Jens Axboeb86ff9812006-03-23 19:56:55 +0100899}
900
901/**
902 * relay_file_mmap - mmap file op for relay files
903 * @filp: the file
904 * @vma: the vma describing what to map
905 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800906 * Calls upon relay_mmap_buf() to map the file into user space.
Jens Axboeb86ff9812006-03-23 19:56:55 +0100907 */
908static int relay_file_mmap(struct file *filp, struct vm_area_struct *vma)
909{
910 struct rchan_buf *buf = filp->private_data;
911 return relay_mmap_buf(buf, vma);
912}
913
914/**
915 * relay_file_poll - poll file op for relay files
916 * @filp: the file
917 * @wait: poll table
918 *
919 * Poll implemention.
920 */
Al Viro9dd95742017-07-03 00:42:43 -0400921static __poll_t relay_file_poll(struct file *filp, poll_table *wait)
Jens Axboeb86ff9812006-03-23 19:56:55 +0100922{
Al Viro9dd95742017-07-03 00:42:43 -0400923 __poll_t mask = 0;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100924 struct rchan_buf *buf = filp->private_data;
925
926 if (buf->finalized)
Linus Torvaldsa9a08842018-02-11 14:34:03 -0800927 return EPOLLERR;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100928
929 if (filp->f_mode & FMODE_READ) {
930 poll_wait(filp, &buf->read_wait, wait);
931 if (!relay_buf_empty(buf))
Linus Torvaldsa9a08842018-02-11 14:34:03 -0800932 mask |= EPOLLIN | EPOLLRDNORM;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100933 }
934
935 return mask;
936}
937
938/**
939 * relay_file_release - release file op for relay files
940 * @inode: the inode
941 * @filp: the file
942 *
943 * Decrements the channel refcount, as the filesystem is
944 * no longer using it.
945 */
946static int relay_file_release(struct inode *inode, struct file *filp)
947{
948 struct rchan_buf *buf = filp->private_data;
949 kref_put(&buf->kref, relay_remove_buf);
950
951 return 0;
952}
953
Randy Dunlap4c78a662006-09-29 01:59:10 -0700954/*
Jens Axboeb86ff9812006-03-23 19:56:55 +0100955 * relay_file_read_consume - update the consumed count for the buffer
956 */
957static void relay_file_read_consume(struct rchan_buf *buf,
958 size_t read_pos,
959 size_t bytes_consumed)
960{
961 size_t subbuf_size = buf->chan->subbuf_size;
962 size_t n_subbufs = buf->chan->n_subbufs;
963 size_t read_subbuf;
964
Tom Zanussi32194452008-08-05 13:01:10 -0700965 if (buf->subbufs_produced == buf->subbufs_consumed &&
966 buf->offset == buf->bytes_consumed)
967 return;
968
Jens Axboeb86ff9812006-03-23 19:56:55 +0100969 if (buf->bytes_consumed + bytes_consumed > subbuf_size) {
970 relay_subbufs_consumed(buf->chan, buf->cpu, 1);
971 buf->bytes_consumed = 0;
972 }
973
974 buf->bytes_consumed += bytes_consumed;
Masami Hiramatsua66e3562007-06-27 14:10:04 -0700975 if (!read_pos)
976 read_subbuf = buf->subbufs_consumed % n_subbufs;
977 else
978 read_subbuf = read_pos / buf->chan->subbuf_size;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100979 if (buf->bytes_consumed + buf->padding[read_subbuf] == subbuf_size) {
980 if ((read_subbuf == buf->subbufs_produced % n_subbufs) &&
981 (buf->offset == subbuf_size))
982 return;
983 relay_subbufs_consumed(buf->chan, buf->cpu, 1);
984 buf->bytes_consumed = 0;
985 }
986}
987
Randy Dunlap4c78a662006-09-29 01:59:10 -0700988/*
Jens Axboeb86ff9812006-03-23 19:56:55 +0100989 * relay_file_read_avail - boolean, are there unconsumed bytes available?
990 */
991static int relay_file_read_avail(struct rchan_buf *buf, size_t read_pos)
992{
Jens Axboeb86ff9812006-03-23 19:56:55 +0100993 size_t subbuf_size = buf->chan->subbuf_size;
994 size_t n_subbufs = buf->chan->n_subbufs;
Jens Axboe221415d2006-03-23 19:57:55 +0100995 size_t produced = buf->subbufs_produced;
996 size_t consumed = buf->subbufs_consumed;
Jens Axboeb86ff9812006-03-23 19:56:55 +0100997
998 relay_file_read_consume(buf, read_pos, 0);
999
Tom Zanussi32194452008-08-05 13:01:10 -07001000 consumed = buf->subbufs_consumed;
1001
Jens Axboe221415d2006-03-23 19:57:55 +01001002 if (unlikely(buf->offset > subbuf_size)) {
1003 if (produced == consumed)
1004 return 0;
1005 return 1;
1006 }
1007
1008 if (unlikely(produced - consumed >= n_subbufs)) {
Masami Hiramatsua66e3562007-06-27 14:10:04 -07001009 consumed = produced - n_subbufs + 1;
Jens Axboe221415d2006-03-23 19:57:55 +01001010 buf->subbufs_consumed = consumed;
Masami Hiramatsua66e3562007-06-27 14:10:04 -07001011 buf->bytes_consumed = 0;
Jens Axboe221415d2006-03-23 19:57:55 +01001012 }
Daniel Walker1bfbc602007-10-18 03:06:05 -07001013
Jens Axboe221415d2006-03-23 19:57:55 +01001014 produced = (produced % n_subbufs) * subbuf_size + buf->offset;
1015 consumed = (consumed % n_subbufs) * subbuf_size + buf->bytes_consumed;
1016
1017 if (consumed > produced)
1018 produced += n_subbufs * subbuf_size;
Daniel Walker1bfbc602007-10-18 03:06:05 -07001019
Tom Zanussi32194452008-08-05 13:01:10 -07001020 if (consumed == produced) {
1021 if (buf->offset == subbuf_size &&
1022 buf->subbufs_produced > buf->subbufs_consumed)
1023 return 1;
Jens Axboe221415d2006-03-23 19:57:55 +01001024 return 0;
Tom Zanussi32194452008-08-05 13:01:10 -07001025 }
Jens Axboe221415d2006-03-23 19:57:55 +01001026
Jens Axboeb86ff9812006-03-23 19:56:55 +01001027 return 1;
1028}
1029
1030/**
1031 * relay_file_read_subbuf_avail - return bytes available in sub-buffer
Randy Dunlap4c78a662006-09-29 01:59:10 -07001032 * @read_pos: file read position
1033 * @buf: relay channel buffer
Jens Axboeb86ff9812006-03-23 19:56:55 +01001034 */
1035static size_t relay_file_read_subbuf_avail(size_t read_pos,
1036 struct rchan_buf *buf)
1037{
1038 size_t padding, avail = 0;
1039 size_t read_subbuf, read_offset, write_subbuf, write_offset;
1040 size_t subbuf_size = buf->chan->subbuf_size;
1041
1042 write_subbuf = (buf->data - buf->start) / subbuf_size;
1043 write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset;
1044 read_subbuf = read_pos / subbuf_size;
1045 read_offset = read_pos % subbuf_size;
1046 padding = buf->padding[read_subbuf];
1047
1048 if (read_subbuf == write_subbuf) {
1049 if (read_offset + padding < write_offset)
1050 avail = write_offset - (read_offset + padding);
1051 } else
1052 avail = (subbuf_size - padding) - read_offset;
1053
1054 return avail;
1055}
1056
1057/**
1058 * relay_file_read_start_pos - find the first available byte to read
Randy Dunlap4c78a662006-09-29 01:59:10 -07001059 * @read_pos: file read position
1060 * @buf: relay channel buffer
Jens Axboeb86ff9812006-03-23 19:56:55 +01001061 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -08001062 * If the @read_pos is in the middle of padding, return the
Jens Axboeb86ff9812006-03-23 19:56:55 +01001063 * position of the first actually available byte, otherwise
1064 * return the original value.
1065 */
1066static size_t relay_file_read_start_pos(size_t read_pos,
1067 struct rchan_buf *buf)
1068{
1069 size_t read_subbuf, padding, padding_start, padding_end;
1070 size_t subbuf_size = buf->chan->subbuf_size;
1071 size_t n_subbufs = buf->chan->n_subbufs;
David Wilder8d62fde2007-06-27 14:10:03 -07001072 size_t consumed = buf->subbufs_consumed % n_subbufs;
Jens Axboeb86ff9812006-03-23 19:56:55 +01001073
David Wilder8d62fde2007-06-27 14:10:03 -07001074 if (!read_pos)
1075 read_pos = consumed * subbuf_size + buf->bytes_consumed;
Jens Axboeb86ff9812006-03-23 19:56:55 +01001076 read_subbuf = read_pos / subbuf_size;
1077 padding = buf->padding[read_subbuf];
1078 padding_start = (read_subbuf + 1) * subbuf_size - padding;
1079 padding_end = (read_subbuf + 1) * subbuf_size;
1080 if (read_pos >= padding_start && read_pos < padding_end) {
1081 read_subbuf = (read_subbuf + 1) % n_subbufs;
1082 read_pos = read_subbuf * subbuf_size;
1083 }
1084
1085 return read_pos;
1086}
1087
1088/**
1089 * relay_file_read_end_pos - return the new read position
Randy Dunlap4c78a662006-09-29 01:59:10 -07001090 * @read_pos: file read position
1091 * @buf: relay channel buffer
1092 * @count: number of bytes to be read
Jens Axboeb86ff9812006-03-23 19:56:55 +01001093 */
1094static size_t relay_file_read_end_pos(struct rchan_buf *buf,
1095 size_t read_pos,
1096 size_t count)
1097{
1098 size_t read_subbuf, padding, end_pos;
1099 size_t subbuf_size = buf->chan->subbuf_size;
1100 size_t n_subbufs = buf->chan->n_subbufs;
1101
1102 read_subbuf = read_pos / subbuf_size;
1103 padding = buf->padding[read_subbuf];
1104 if (read_pos % subbuf_size + count + padding == subbuf_size)
1105 end_pos = (read_subbuf + 1) * subbuf_size;
1106 else
1107 end_pos = read_pos + count;
1108 if (end_pos >= subbuf_size * n_subbufs)
1109 end_pos = 0;
1110
1111 return end_pos;
1112}
1113
Al Viroa7c22422016-09-25 22:52:02 -04001114static ssize_t relay_file_read(struct file *filp,
1115 char __user *buffer,
1116 size_t count,
1117 loff_t *ppos)
Tom Zanussi6dac40a2006-03-23 19:58:45 +01001118{
1119 struct rchan_buf *buf = filp->private_data;
1120 size_t read_start, avail;
Al Viroa7c22422016-09-25 22:52:02 -04001121 size_t written = 0;
Tom Zanussi6dac40a2006-03-23 19:58:45 +01001122 int ret;
1123
Al Viroa7c22422016-09-25 22:52:02 -04001124 if (!count)
Jens Axboe221415d2006-03-23 19:57:55 +01001125 return 0;
1126
Al Viro59551022016-01-22 15:40:57 -05001127 inode_lock(file_inode(filp));
Tom Zanussi6dac40a2006-03-23 19:58:45 +01001128 do {
Al Viroa7c22422016-09-25 22:52:02 -04001129 void *from;
1130
Tom Zanussi6dac40a2006-03-23 19:58:45 +01001131 if (!relay_file_read_avail(buf, *ppos))
Jens Axboe221415d2006-03-23 19:57:55 +01001132 break;
Tom Zanussi6dac40a2006-03-23 19:58:45 +01001133
1134 read_start = relay_file_read_start_pos(*ppos, buf);
1135 avail = relay_file_read_subbuf_avail(read_start, buf);
1136 if (!avail)
1137 break;
1138
Al Viroa7c22422016-09-25 22:52:02 -04001139 avail = min(count, avail);
1140 from = buf->start + read_start;
1141 ret = avail;
1142 if (copy_to_user(buffer, from, avail))
Tom Zanussi6dac40a2006-03-23 19:58:45 +01001143 break;
1144
Al Viroa7c22422016-09-25 22:52:02 -04001145 buffer += ret;
1146 written += ret;
1147 count -= ret;
1148
1149 relay_file_read_consume(buf, read_start, ret);
1150 *ppos = relay_file_read_end_pos(buf, read_start, ret);
1151 } while (count);
Al Viro59551022016-01-22 15:40:57 -05001152 inode_unlock(file_inode(filp));
Jens Axboe221415d2006-03-23 19:57:55 +01001153
Al Viroa7c22422016-09-25 22:52:02 -04001154 return written;
Tom Zanussi6dac40a2006-03-23 19:58:45 +01001155}
1156
Jens Axboe1db60cf2007-06-12 08:43:46 +02001157static void relay_consume_bytes(struct rchan_buf *rbuf, int bytes_consumed)
1158{
1159 rbuf->bytes_consumed += bytes_consumed;
1160
1161 if (rbuf->bytes_consumed >= rbuf->chan->subbuf_size) {
1162 relay_subbufs_consumed(rbuf->chan, rbuf->cpu, 1);
1163 rbuf->bytes_consumed %= rbuf->chan->subbuf_size;
1164 }
1165}
1166
Tom Zanussiebf99092007-06-04 09:12:05 +02001167static void relay_pipe_buf_release(struct pipe_inode_info *pipe,
1168 struct pipe_buffer *buf)
Jens Axboe221415d2006-03-23 19:57:55 +01001169{
Tom Zanussiebf99092007-06-04 09:12:05 +02001170 struct rchan_buf *rbuf;
1171
1172 rbuf = (struct rchan_buf *)page_private(buf->page);
Jens Axboe1db60cf2007-06-12 08:43:46 +02001173 relay_consume_bytes(rbuf, buf->private);
Tom Zanussiebf99092007-06-04 09:12:05 +02001174}
1175
Alexey Dobriyan28dfef82009-12-15 16:46:48 -08001176static const struct pipe_buf_operations relay_pipe_buf_ops = {
Tom Zanussiebf99092007-06-04 09:12:05 +02001177 .can_merge = 0,
Jens Axboecac36bb02007-06-14 13:10:48 +02001178 .confirm = generic_pipe_buf_confirm,
Tom Zanussiebf99092007-06-04 09:12:05 +02001179 .release = relay_pipe_buf_release,
1180 .steal = generic_pipe_buf_steal,
1181 .get = generic_pipe_buf_get,
1182};
1183
Jens Axboe5eb7f9f2008-03-26 12:04:09 +01001184static void relay_page_release(struct splice_pipe_desc *spd, unsigned int i)
1185{
1186}
1187
Tom Zanussid3f35d982007-07-12 08:12:05 +02001188/*
Tom Zanussiebf99092007-06-04 09:12:05 +02001189 * subbuf_splice_actor - splice up to one subbuf's worth of data
1190 */
Dan Carpenter5f1664f2010-03-05 13:42:51 -08001191static ssize_t subbuf_splice_actor(struct file *in,
Tom Zanussiebf99092007-06-04 09:12:05 +02001192 loff_t *ppos,
1193 struct pipe_inode_info *pipe,
1194 size_t len,
1195 unsigned int flags,
1196 int *nonpad_ret)
1197{
Dan Carpenter5f1664f2010-03-05 13:42:51 -08001198 unsigned int pidx, poff, total_len, subbuf_pages, nr_pages;
Tom Zanussiebf99092007-06-04 09:12:05 +02001199 struct rchan_buf *rbuf = in->private_data;
1200 unsigned int subbuf_size = rbuf->chan->subbuf_size;
Tom Zanussi24da24d2007-07-12 08:12:04 +02001201 uint64_t pos = (uint64_t) *ppos;
1202 uint32_t alloc_size = (uint32_t) rbuf->chan->alloc_size;
1203 size_t read_start = (size_t) do_div(pos, alloc_size);
Tom Zanussiebf99092007-06-04 09:12:05 +02001204 size_t read_subbuf = read_start / subbuf_size;
1205 size_t padding = rbuf->padding[read_subbuf];
1206 size_t nonpad_end = read_subbuf * subbuf_size + subbuf_size - padding;
Jens Axboe35f3d142010-05-20 10:43:18 +02001207 struct page *pages[PIPE_DEF_BUFFERS];
1208 struct partial_page partial[PIPE_DEF_BUFFERS];
Jens Axboe1db60cf2007-06-12 08:43:46 +02001209 struct splice_pipe_desc spd = {
1210 .pages = pages,
1211 .nr_pages = 0,
Eric Dumazet047fe362012-06-12 15:24:40 +02001212 .nr_pages_max = PIPE_DEF_BUFFERS,
Jens Axboe1db60cf2007-06-12 08:43:46 +02001213 .partial = partial,
Jens Axboe1db60cf2007-06-12 08:43:46 +02001214 .ops = &relay_pipe_buf_ops,
Jens Axboe5eb7f9f2008-03-26 12:04:09 +01001215 .spd_release = relay_page_release,
Jens Axboe1db60cf2007-06-12 08:43:46 +02001216 };
Dan Carpenter5f1664f2010-03-05 13:42:51 -08001217 ssize_t ret;
Tom Zanussiebf99092007-06-04 09:12:05 +02001218
1219 if (rbuf->subbufs_produced == rbuf->subbufs_consumed)
1220 return 0;
Jens Axboe35f3d142010-05-20 10:43:18 +02001221 if (splice_grow_spd(pipe, &spd))
1222 return -ENOMEM;
Tom Zanussiebf99092007-06-04 09:12:05 +02001223
Jens Axboe1db60cf2007-06-12 08:43:46 +02001224 /*
1225 * Adjust read len, if longer than what is available
1226 */
1227 if (len > (subbuf_size - read_start % subbuf_size))
1228 len = subbuf_size - read_start % subbuf_size;
Tom Zanussiebf99092007-06-04 09:12:05 +02001229
1230 subbuf_pages = rbuf->chan->alloc_size >> PAGE_SHIFT;
1231 pidx = (read_start / PAGE_SIZE) % subbuf_pages;
1232 poff = read_start & ~PAGE_MASK;
Al Viroa786c062014-04-11 12:01:03 -04001233 nr_pages = min_t(unsigned int, subbuf_pages, spd.nr_pages_max);
Tom Zanussiebf99092007-06-04 09:12:05 +02001234
Jens Axboe16d546692008-03-17 09:04:59 +01001235 for (total_len = 0; spd.nr_pages < nr_pages; spd.nr_pages++) {
Jens Axboe1db60cf2007-06-12 08:43:46 +02001236 unsigned int this_len, this_end, private;
1237 unsigned int cur_pos = read_start + total_len;
Tom Zanussiebf99092007-06-04 09:12:05 +02001238
Jens Axboe1db60cf2007-06-12 08:43:46 +02001239 if (!len)
1240 break;
1241
1242 this_len = min_t(unsigned long, len, PAGE_SIZE - poff);
1243 private = this_len;
1244
1245 spd.pages[spd.nr_pages] = rbuf->page_array[pidx];
1246 spd.partial[spd.nr_pages].offset = poff;
1247
1248 this_end = cur_pos + this_len;
1249 if (this_end >= nonpad_end) {
1250 this_len = nonpad_end - cur_pos;
1251 private = this_len + padding;
1252 }
1253 spd.partial[spd.nr_pages].len = this_len;
1254 spd.partial[spd.nr_pages].private = private;
1255
1256 len -= this_len;
1257 total_len += this_len;
1258 poff = 0;
1259 pidx = (pidx + 1) % subbuf_pages;
1260
1261 if (this_end >= nonpad_end) {
1262 spd.nr_pages++;
Tom Zanussiebf99092007-06-04 09:12:05 +02001263 break;
1264 }
Tom Zanussiebf99092007-06-04 09:12:05 +02001265 }
1266
Jens Axboe35f3d142010-05-20 10:43:18 +02001267 ret = 0;
Jens Axboe1db60cf2007-06-12 08:43:46 +02001268 if (!spd.nr_pages)
Jens Axboe35f3d142010-05-20 10:43:18 +02001269 goto out;
Tom Zanussiebf99092007-06-04 09:12:05 +02001270
Jens Axboe1db60cf2007-06-12 08:43:46 +02001271 ret = *nonpad_ret = splice_to_pipe(pipe, &spd);
1272 if (ret < 0 || ret < total_len)
Jens Axboe35f3d142010-05-20 10:43:18 +02001273 goto out;
Tom Zanussiebf99092007-06-04 09:12:05 +02001274
Jens Axboe1db60cf2007-06-12 08:43:46 +02001275 if (read_start + ret == nonpad_end)
1276 ret += padding;
1277
Jens Axboe35f3d142010-05-20 10:43:18 +02001278out:
Eric Dumazet047fe362012-06-12 15:24:40 +02001279 splice_shrink_spd(&spd);
1280 return ret;
Tom Zanussiebf99092007-06-04 09:12:05 +02001281}
1282
1283static ssize_t relay_file_splice_read(struct file *in,
1284 loff_t *ppos,
1285 struct pipe_inode_info *pipe,
1286 size_t len,
1287 unsigned int flags)
1288{
1289 ssize_t spliced;
1290 int ret;
1291 int nonpad_ret = 0;
1292
1293 ret = 0;
1294 spliced = 0;
1295
Tom Zanussia82c53a2008-05-09 13:28:36 +02001296 while (len && !spliced) {
Tom Zanussiebf99092007-06-04 09:12:05 +02001297 ret = subbuf_splice_actor(in, ppos, pipe, len, flags, &nonpad_ret);
1298 if (ret < 0)
1299 break;
1300 else if (!ret) {
Tom Zanussifbb5b7a2008-12-09 13:14:10 -08001301 if (flags & SPLICE_F_NONBLOCK)
Tom Zanussiebf99092007-06-04 09:12:05 +02001302 ret = -EAGAIN;
Tom Zanussifbb5b7a2008-12-09 13:14:10 -08001303 break;
Tom Zanussiebf99092007-06-04 09:12:05 +02001304 }
1305
1306 *ppos += ret;
1307 if (ret > len)
1308 len = 0;
1309 else
1310 len -= ret;
1311 spliced += nonpad_ret;
1312 nonpad_ret = 0;
1313 }
1314
1315 if (spliced)
1316 return spliced;
1317
1318 return ret;
Jens Axboe221415d2006-03-23 19:57:55 +01001319}
1320
Helge Deller15ad7cd2006-12-06 20:40:36 -08001321const struct file_operations relay_file_operations = {
Jens Axboeb86ff9812006-03-23 19:56:55 +01001322 .open = relay_file_open,
1323 .poll = relay_file_poll,
1324 .mmap = relay_file_mmap,
1325 .read = relay_file_read,
1326 .llseek = no_llseek,
1327 .release = relay_file_release,
Tom Zanussiebf99092007-06-04 09:12:05 +02001328 .splice_read = relay_file_splice_read,
Jens Axboeb86ff9812006-03-23 19:56:55 +01001329};
1330EXPORT_SYMBOL_GPL(relay_file_operations);