2 * ring_buffer_backend.c
4 * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; only
9 * version 2.1 of the License.
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 #include <linux/stddef.h>
22 #include <linux/module.h>
23 #include <linux/string.h>
24 #include <linux/bitops.h>
25 #include <linux/delay.h>
26 #include <linux/errno.h>
27 #include <linux/slab.h>
28 #include <linux/cpu.h>
31 #include "../../wrapper/vmalloc.h" /* for wrapper_vmalloc_sync_all() */
32 #include "../../wrapper/ringbuffer/config.h"
33 #include "../../wrapper/ringbuffer/backend.h"
34 #include "../../wrapper/ringbuffer/frontend.h"
37 * lib_ring_buffer_backend_allocate - allocate a channel buffer
38 * @config: ring buffer instance configuration
39 * @buf: the buffer struct
40 * @size: total size of the buffer
41 * @num_subbuf: number of subbuffers
42 * @extra_reader_sb: need extra subbuffer for reader
45 int lib_ring_buffer_backend_allocate(const struct lib_ring_buffer_config
*config
,
46 struct lib_ring_buffer_backend
*bufb
,
47 size_t size
, size_t num_subbuf
,
50 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
51 unsigned long j
, num_pages
, num_pages_per_subbuf
, page_idx
= 0;
52 unsigned long subbuf_size
, mmap_offset
= 0;
53 unsigned long num_subbuf_alloc
;
58 num_pages
= size
>> PAGE_SHIFT
;
59 num_pages_per_subbuf
= num_pages
>> get_count_order(num_subbuf
);
60 subbuf_size
= chanb
->subbuf_size
;
61 num_subbuf_alloc
= num_subbuf
;
63 if (extra_reader_sb
) {
64 num_pages
+= num_pages_per_subbuf
; /* Add pages for reader */
68 pages
= kmalloc_node(ALIGN(sizeof(*pages
) * num_pages
,
69 1 << INTERNODE_CACHE_SHIFT
),
70 GFP_KERNEL
, cpu_to_node(max(bufb
->cpu
, 0)));
74 virt
= kmalloc_node(ALIGN(sizeof(*virt
) * num_pages
,
75 1 << INTERNODE_CACHE_SHIFT
),
76 GFP_KERNEL
, cpu_to_node(max(bufb
->cpu
, 0)));
80 bufb
->array
= kmalloc_node(ALIGN(sizeof(*bufb
->array
)
82 1 << INTERNODE_CACHE_SHIFT
),
83 GFP_KERNEL
, cpu_to_node(max(bufb
->cpu
, 0)));
84 if (unlikely(!bufb
->array
))
87 for (i
= 0; i
< num_pages
; i
++) {
88 pages
[i
] = alloc_pages_node(cpu_to_node(max(bufb
->cpu
, 0)),
89 GFP_KERNEL
| __GFP_ZERO
, 0);
90 if (unlikely(!pages
[i
]))
92 virt
[i
] = page_address(pages
[i
]);
94 bufb
->num_pages_per_subbuf
= num_pages_per_subbuf
;
96 /* Allocate backend pages array elements */
97 for (i
= 0; i
< num_subbuf_alloc
; i
++) {
100 sizeof(struct lib_ring_buffer_backend_pages
) +
101 sizeof(struct lib_ring_buffer_backend_page
)
102 * num_pages_per_subbuf
,
103 1 << INTERNODE_CACHE_SHIFT
),
104 GFP_KERNEL
, cpu_to_node(max(bufb
->cpu
, 0)));
109 /* Allocate write-side subbuffer table */
110 bufb
->buf_wsb
= kzalloc_node(ALIGN(
111 sizeof(struct lib_ring_buffer_backend_subbuffer
)
113 1 << INTERNODE_CACHE_SHIFT
),
114 GFP_KERNEL
, cpu_to_node(max(bufb
->cpu
, 0)));
115 if (unlikely(!bufb
->buf_wsb
))
118 for (i
= 0; i
< num_subbuf
; i
++)
119 bufb
->buf_wsb
[i
].id
= subbuffer_id(config
, 0, 1, i
);
121 /* Assign read-side subbuffer table */
123 bufb
->buf_rsb
.id
= subbuffer_id(config
, 0, 1,
124 num_subbuf_alloc
- 1);
126 bufb
->buf_rsb
.id
= subbuffer_id(config
, 0, 1, 0);
128 /* Assign pages to page index */
129 for (i
= 0; i
< num_subbuf_alloc
; i
++) {
130 for (j
= 0; j
< num_pages_per_subbuf
; j
++) {
131 CHAN_WARN_ON(chanb
, page_idx
> num_pages
);
132 bufb
->array
[i
]->p
[j
].virt
= virt
[page_idx
];
133 bufb
->array
[i
]->p
[j
].page
= pages
[page_idx
];
136 if (config
->output
== RING_BUFFER_MMAP
) {
137 bufb
->array
[i
]->mmap_offset
= mmap_offset
;
138 mmap_offset
+= subbuf_size
;
143 * If kmalloc ever uses vmalloc underneath, make sure the buffer pages
146 wrapper_vmalloc_sync_all();
152 for (i
= 0; (i
< num_subbuf_alloc
&& bufb
->array
[i
]); i
++)
153 kfree(bufb
->array
[i
]);
155 /* Free all allocated pages */
156 for (i
= 0; (i
< num_pages
&& pages
[i
]); i
++)
157 __free_page(pages
[i
]);
167 int lib_ring_buffer_backend_create(struct lib_ring_buffer_backend
*bufb
,
168 struct channel_backend
*chanb
, int cpu
)
170 const struct lib_ring_buffer_config
*config
= &chanb
->config
;
172 bufb
->chan
= container_of(chanb
, struct channel
, backend
);
175 return lib_ring_buffer_backend_allocate(config
, bufb
, chanb
->buf_size
,
177 chanb
->extra_reader_sb
);
180 void lib_ring_buffer_backend_free(struct lib_ring_buffer_backend
*bufb
)
182 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
183 unsigned long i
, j
, num_subbuf_alloc
;
185 num_subbuf_alloc
= chanb
->num_subbuf
;
186 if (chanb
->extra_reader_sb
)
189 kfree(bufb
->buf_wsb
);
190 for (i
= 0; i
< num_subbuf_alloc
; i
++) {
191 for (j
= 0; j
< bufb
->num_pages_per_subbuf
; j
++)
192 __free_page(bufb
->array
[i
]->p
[j
].page
);
193 kfree(bufb
->array
[i
]);
199 void lib_ring_buffer_backend_reset(struct lib_ring_buffer_backend
*bufb
)
201 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
202 const struct lib_ring_buffer_config
*config
= &chanb
->config
;
203 unsigned long num_subbuf_alloc
;
206 num_subbuf_alloc
= chanb
->num_subbuf
;
207 if (chanb
->extra_reader_sb
)
210 for (i
= 0; i
< chanb
->num_subbuf
; i
++)
211 bufb
->buf_wsb
[i
].id
= subbuffer_id(config
, 0, 1, i
);
212 if (chanb
->extra_reader_sb
)
213 bufb
->buf_rsb
.id
= subbuffer_id(config
, 0, 1,
214 num_subbuf_alloc
- 1);
216 bufb
->buf_rsb
.id
= subbuffer_id(config
, 0, 1, 0);
218 for (i
= 0; i
< num_subbuf_alloc
; i
++) {
219 /* Don't reset mmap_offset */
220 v_set(config
, &bufb
->array
[i
]->records_commit
, 0);
221 v_set(config
, &bufb
->array
[i
]->records_unread
, 0);
222 bufb
->array
[i
]->data_size
= 0;
223 /* Don't reset backend page and virt addresses */
225 /* Don't reset num_pages_per_subbuf, cpu, allocated */
226 v_set(config
, &bufb
->records_read
, 0);
230 * The frontend is responsible for also calling ring_buffer_backend_reset for
231 * each buffer when calling channel_backend_reset.
233 void channel_backend_reset(struct channel_backend
*chanb
)
235 struct channel
*chan
= container_of(chanb
, struct channel
, backend
);
236 const struct lib_ring_buffer_config
*config
= &chanb
->config
;
239 * Don't reset buf_size, subbuf_size, subbuf_size_order,
240 * num_subbuf_order, buf_size_order, extra_reader_sb, num_subbuf,
241 * priv, notifiers, config, cpumask and name.
243 chanb
->start_tsc
= config
->cb
.ring_buffer_clock_read(chan
);
246 #ifdef CONFIG_HOTPLUG_CPU
248 * lib_ring_buffer_cpu_hp_callback - CPU hotplug callback
249 * @nb: notifier block
250 * @action: hotplug action to take
253 * Returns the success/failure of the operation. (%NOTIFY_OK, %NOTIFY_BAD)
256 int __cpuinit
lib_ring_buffer_cpu_hp_callback(struct notifier_block
*nb
,
257 unsigned long action
,
260 unsigned int cpu
= (unsigned long)hcpu
;
261 struct channel_backend
*chanb
= container_of(nb
, struct channel_backend
,
263 const struct lib_ring_buffer_config
*config
= &chanb
->config
;
264 struct lib_ring_buffer
*buf
;
267 CHAN_WARN_ON(chanb
, config
->alloc
== RING_BUFFER_ALLOC_GLOBAL
);
271 case CPU_UP_PREPARE_FROZEN
:
272 buf
= per_cpu_ptr(chanb
->buf
, cpu
);
273 ret
= lib_ring_buffer_create(buf
, chanb
, cpu
);
276 "ring_buffer_cpu_hp_callback: cpu %d "
277 "buffer creation failed\n", cpu
);
282 case CPU_DEAD_FROZEN
:
283 /* No need to do a buffer switch here, because it will happen
284 * when tracing is stopped, or will be done by switch timer CPU
293 * channel_backend_init - initialize a channel backend
294 * @chanb: channel backend
295 * @name: channel name
296 * @config: client ring buffer configuration
297 * @priv: client private data
298 * @parent: dentry of parent directory, %NULL for root directory
299 * @subbuf_size: size of sub-buffers (> PAGE_SIZE, power of 2)
300 * @num_subbuf: number of sub-buffers (power of 2)
302 * Returns channel pointer if successful, %NULL otherwise.
304 * Creates per-cpu channel buffers using the sizes and attributes
305 * specified. The created channel buffer files will be named
306 * name_0...name_N-1. File permissions will be %S_IRUSR.
308 * Called with CPU hotplug disabled.
310 int channel_backend_init(struct channel_backend
*chanb
,
312 const struct lib_ring_buffer_config
*config
,
313 void *priv
, size_t subbuf_size
, size_t num_subbuf
)
315 struct channel
*chan
= container_of(chanb
, struct channel
, backend
);
322 /* Check that the subbuffer size is larger than a page. */
323 if (subbuf_size
< PAGE_SIZE
)
327 * Make sure the number of subbuffers and subbuffer size are
328 * power of 2 and nonzero.
330 if (!subbuf_size
|| (subbuf_size
& (subbuf_size
- 1)))
332 if (!num_subbuf
|| (num_subbuf
& (num_subbuf
- 1)))
335 ret
= subbuffer_id_check_index(config
, num_subbuf
);
340 chanb
->buf_size
= num_subbuf
* subbuf_size
;
341 chanb
->subbuf_size
= subbuf_size
;
342 chanb
->buf_size_order
= get_count_order(chanb
->buf_size
);
343 chanb
->subbuf_size_order
= get_count_order(subbuf_size
);
344 chanb
->num_subbuf_order
= get_count_order(num_subbuf
);
345 chanb
->extra_reader_sb
=
346 (config
->mode
== RING_BUFFER_OVERWRITE
) ? 1 : 0;
347 chanb
->num_subbuf
= num_subbuf
;
348 strlcpy(chanb
->name
, name
, NAME_MAX
);
349 memcpy(&chanb
->config
, config
, sizeof(chanb
->config
));
351 if (config
->alloc
== RING_BUFFER_ALLOC_PER_CPU
) {
352 if (!zalloc_cpumask_var(&chanb
->cpumask
, GFP_KERNEL
))
356 if (config
->alloc
== RING_BUFFER_ALLOC_PER_CPU
) {
357 /* Allocating the buffer per-cpu structures */
358 chanb
->buf
= alloc_percpu(struct lib_ring_buffer
);
363 * In case of non-hotplug cpu, if the ring-buffer is allocated
364 * in early initcall, it will not be notified of secondary cpus.
365 * In that off case, we need to allocate for all possible cpus.
367 #ifdef CONFIG_HOTPLUG_CPU
369 * buf->backend.allocated test takes care of concurrent CPU
371 * Priority higher than frontend, so we create the ring buffer
372 * before we start the timer.
374 chanb
->cpu_hp_notifier
.notifier_call
=
375 lib_ring_buffer_cpu_hp_callback
;
376 chanb
->cpu_hp_notifier
.priority
= 5;
377 register_hotcpu_notifier(&chanb
->cpu_hp_notifier
);
380 for_each_online_cpu(i
) {
381 ret
= lib_ring_buffer_create(per_cpu_ptr(chanb
->buf
, i
),
384 goto free_bufs
; /* cpu hotplug locked */
388 for_each_possible_cpu(i
) {
389 ret
= lib_ring_buffer_create(per_cpu_ptr(chanb
->buf
, i
),
392 goto free_bufs
; /* cpu hotplug locked */
396 chanb
->buf
= kzalloc(sizeof(struct lib_ring_buffer
), GFP_KERNEL
);
399 ret
= lib_ring_buffer_create(chanb
->buf
, chanb
, -1);
403 chanb
->start_tsc
= config
->cb
.ring_buffer_clock_read(chan
);
408 if (config
->alloc
== RING_BUFFER_ALLOC_PER_CPU
) {
409 for_each_possible_cpu(i
) {
410 struct lib_ring_buffer
*buf
= per_cpu_ptr(chanb
->buf
, i
);
412 if (!buf
->backend
.allocated
)
414 lib_ring_buffer_free(buf
);
416 #ifdef CONFIG_HOTPLUG_CPU
419 free_percpu(chanb
->buf
);
423 if (config
->alloc
== RING_BUFFER_ALLOC_PER_CPU
)
424 free_cpumask_var(chanb
->cpumask
);
429 * channel_backend_unregister_notifiers - unregister notifiers
434 void channel_backend_unregister_notifiers(struct channel_backend
*chanb
)
436 const struct lib_ring_buffer_config
*config
= &chanb
->config
;
438 if (config
->alloc
== RING_BUFFER_ALLOC_PER_CPU
)
439 unregister_hotcpu_notifier(&chanb
->cpu_hp_notifier
);
443 * channel_backend_free - destroy the channel
446 * Destroy all channel buffers and frees the channel.
448 void channel_backend_free(struct channel_backend
*chanb
)
450 const struct lib_ring_buffer_config
*config
= &chanb
->config
;
453 if (config
->alloc
== RING_BUFFER_ALLOC_PER_CPU
) {
454 for_each_possible_cpu(i
) {
455 struct lib_ring_buffer
*buf
= per_cpu_ptr(chanb
->buf
, i
);
457 if (!buf
->backend
.allocated
)
459 lib_ring_buffer_free(buf
);
461 free_cpumask_var(chanb
->cpumask
);
462 free_percpu(chanb
->buf
);
464 struct lib_ring_buffer
*buf
= chanb
->buf
;
466 CHAN_WARN_ON(chanb
, !buf
->backend
.allocated
);
467 lib_ring_buffer_free(buf
);
473 * lib_ring_buffer_write - write data to a ring_buffer buffer.
474 * @bufb : buffer backend
475 * @offset : offset within the buffer
476 * @src : source address
477 * @len : length to write
478 * @pagecpy : page size copied so far
480 void _lib_ring_buffer_write(struct lib_ring_buffer_backend
*bufb
, size_t offset
,
481 const void *src
, size_t len
, ssize_t pagecpy
)
483 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
484 const struct lib_ring_buffer_config
*config
= &chanb
->config
;
486 struct lib_ring_buffer_backend_pages
*rpages
;
487 unsigned long sb_bindex
, id
;
493 sbidx
= offset
>> chanb
->subbuf_size_order
;
494 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
497 * Underlying layer should never ask for writes across
500 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
502 pagecpy
= min_t(size_t, len
, PAGE_SIZE
- (offset
& ~PAGE_MASK
));
503 id
= bufb
->buf_wsb
[sbidx
].id
;
504 sb_bindex
= subbuffer_id_get_index(config
, id
);
505 rpages
= bufb
->array
[sb_bindex
];
506 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
507 && subbuffer_id_is_noref(config
, id
));
508 lib_ring_buffer_do_copy(config
,
509 rpages
->p
[index
].virt
510 + (offset
& ~PAGE_MASK
),
512 } while (unlikely(len
!= pagecpy
));
514 EXPORT_SYMBOL_GPL(_lib_ring_buffer_write
);
518 * lib_ring_buffer_memset - write len bytes of c to a ring_buffer buffer.
519 * @bufb : buffer backend
520 * @offset : offset within the buffer
521 * @c : the byte to write
522 * @len : length to write
523 * @pagecpy : page size copied so far
525 void _lib_ring_buffer_memset(struct lib_ring_buffer_backend
*bufb
,
527 int c
, size_t len
, ssize_t pagecpy
)
529 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
530 const struct lib_ring_buffer_config
*config
= &chanb
->config
;
532 struct lib_ring_buffer_backend_pages
*rpages
;
533 unsigned long sb_bindex
, id
;
538 sbidx
= offset
>> chanb
->subbuf_size_order
;
539 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
542 * Underlying layer should never ask for writes across
545 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
547 pagecpy
= min_t(size_t, len
, PAGE_SIZE
- (offset
& ~PAGE_MASK
));
548 id
= bufb
->buf_wsb
[sbidx
].id
;
549 sb_bindex
= subbuffer_id_get_index(config
, id
);
550 rpages
= bufb
->array
[sb_bindex
];
551 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
552 && subbuffer_id_is_noref(config
, id
));
553 lib_ring_buffer_do_memset(rpages
->p
[index
].virt
554 + (offset
& ~PAGE_MASK
),
556 } while (unlikely(len
!= pagecpy
));
558 EXPORT_SYMBOL_GPL(_lib_ring_buffer_memset
);
562 * lib_ring_buffer_copy_from_user_inatomic - write user data to a ring_buffer buffer.
563 * @bufb : buffer backend
564 * @offset : offset within the buffer
565 * @src : source address
566 * @len : length to write
567 * @pagecpy : page size copied so far
569 * This function deals with userspace pointers, it should never be called
570 * directly without having the src pointer checked with access_ok()
573 void _lib_ring_buffer_copy_from_user_inatomic(struct lib_ring_buffer_backend
*bufb
,
575 const void __user
*src
, size_t len
,
578 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
579 const struct lib_ring_buffer_config
*config
= &chanb
->config
;
581 struct lib_ring_buffer_backend_pages
*rpages
;
582 unsigned long sb_bindex
, id
;
589 sbidx
= offset
>> chanb
->subbuf_size_order
;
590 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
593 * Underlying layer should never ask for writes across
596 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
598 pagecpy
= min_t(size_t, len
, PAGE_SIZE
- (offset
& ~PAGE_MASK
));
599 id
= bufb
->buf_wsb
[sbidx
].id
;
600 sb_bindex
= subbuffer_id_get_index(config
, id
);
601 rpages
= bufb
->array
[sb_bindex
];
602 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
603 && subbuffer_id_is_noref(config
, id
));
604 ret
= lib_ring_buffer_do_copy_from_user_inatomic(rpages
->p
[index
].virt
605 + (offset
& ~PAGE_MASK
),
608 offset
+= (pagecpy
- ret
);
609 len
-= (pagecpy
- ret
);
610 _lib_ring_buffer_memset(bufb
, offset
, 0, len
, 0);
611 break; /* stop copy */
613 } while (unlikely(len
!= pagecpy
));
615 EXPORT_SYMBOL_GPL(_lib_ring_buffer_copy_from_user_inatomic
);
618 * lib_ring_buffer_read - read data from ring_buffer_buffer.
619 * @bufb : buffer backend
620 * @offset : offset within the buffer
621 * @dest : destination address
622 * @len : length to copy to destination
624 * Should be protected by get_subbuf/put_subbuf.
625 * Returns the length copied.
627 size_t lib_ring_buffer_read(struct lib_ring_buffer_backend
*bufb
, size_t offset
,
628 void *dest
, size_t len
)
630 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
631 const struct lib_ring_buffer_config
*config
= &chanb
->config
;
633 ssize_t pagecpy
, orig_len
;
634 struct lib_ring_buffer_backend_pages
*rpages
;
635 unsigned long sb_bindex
, id
;
638 offset
&= chanb
->buf_size
- 1;
639 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
643 pagecpy
= min_t(size_t, len
, PAGE_SIZE
- (offset
& ~PAGE_MASK
));
644 id
= bufb
->buf_rsb
.id
;
645 sb_bindex
= subbuffer_id_get_index(config
, id
);
646 rpages
= bufb
->array
[sb_bindex
];
647 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
648 && subbuffer_id_is_noref(config
, id
));
649 memcpy(dest
, rpages
->p
[index
].virt
+ (offset
& ~PAGE_MASK
),
656 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
658 * Underlying layer should never ask for reads across
661 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
665 EXPORT_SYMBOL_GPL(lib_ring_buffer_read
);
668 * __lib_ring_buffer_copy_to_user - read data from ring_buffer to userspace
669 * @bufb : buffer backend
670 * @offset : offset within the buffer
671 * @dest : destination userspace address
672 * @len : length to copy to destination
674 * Should be protected by get_subbuf/put_subbuf.
675 * access_ok() must have been performed on dest addresses prior to call this
677 * Returns -EFAULT on error, 0 if ok.
679 int __lib_ring_buffer_copy_to_user(struct lib_ring_buffer_backend
*bufb
,
680 size_t offset
, void __user
*dest
, size_t len
)
682 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
683 const struct lib_ring_buffer_config
*config
= &chanb
->config
;
686 struct lib_ring_buffer_backend_pages
*rpages
;
687 unsigned long sb_bindex
, id
;
689 offset
&= chanb
->buf_size
- 1;
690 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
694 pagecpy
= min_t(size_t, len
, PAGE_SIZE
- (offset
& ~PAGE_MASK
));
695 id
= bufb
->buf_rsb
.id
;
696 sb_bindex
= subbuffer_id_get_index(config
, id
);
697 rpages
= bufb
->array
[sb_bindex
];
698 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
699 && subbuffer_id_is_noref(config
, id
));
700 if (__copy_to_user(dest
,
701 rpages
->p
[index
].virt
+ (offset
& ~PAGE_MASK
),
709 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
711 * Underlying layer should never ask for reads across
714 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
718 EXPORT_SYMBOL_GPL(__lib_ring_buffer_copy_to_user
);
721 * lib_ring_buffer_read_cstr - read a C-style string from ring_buffer.
722 * @bufb : buffer backend
723 * @offset : offset within the buffer
724 * @dest : destination address
725 * @len : destination's length
727 * return string's length
728 * Should be protected by get_subbuf/put_subbuf.
730 int lib_ring_buffer_read_cstr(struct lib_ring_buffer_backend
*bufb
, size_t offset
,
731 void *dest
, size_t len
)
733 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
734 const struct lib_ring_buffer_config
*config
= &chanb
->config
;
736 ssize_t pagecpy
, pagelen
, strpagelen
, orig_offset
;
738 struct lib_ring_buffer_backend_pages
*rpages
;
739 unsigned long sb_bindex
, id
;
741 offset
&= chanb
->buf_size
- 1;
742 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
743 orig_offset
= offset
;
745 id
= bufb
->buf_rsb
.id
;
746 sb_bindex
= subbuffer_id_get_index(config
, id
);
747 rpages
= bufb
->array
[sb_bindex
];
748 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
749 && subbuffer_id_is_noref(config
, id
));
750 str
= (char *)rpages
->p
[index
].virt
+ (offset
& ~PAGE_MASK
);
751 pagelen
= PAGE_SIZE
- (offset
& ~PAGE_MASK
);
752 strpagelen
= strnlen(str
, pagelen
);
754 pagecpy
= min_t(size_t, len
, strpagelen
);
756 memcpy(dest
, str
, pagecpy
);
761 offset
+= strpagelen
;
762 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
763 if (strpagelen
< pagelen
)
766 * Underlying layer should never ask for reads across
769 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
772 ((char *)dest
)[0] = 0;
773 return offset
- orig_offset
;
775 EXPORT_SYMBOL_GPL(lib_ring_buffer_read_cstr
);
778 * lib_ring_buffer_read_get_page - Get a whole page to read from
779 * @bufb : buffer backend
780 * @offset : offset within the buffer
781 * @virt : pointer to page address (output)
783 * Should be protected by get_subbuf/put_subbuf.
784 * Returns the pointer to the page struct pointer.
786 struct page
**lib_ring_buffer_read_get_page(struct lib_ring_buffer_backend
*bufb
,
787 size_t offset
, void ***virt
)
790 struct lib_ring_buffer_backend_pages
*rpages
;
791 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
792 const struct lib_ring_buffer_config
*config
= &chanb
->config
;
793 unsigned long sb_bindex
, id
;
795 offset
&= chanb
->buf_size
- 1;
796 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
797 id
= bufb
->buf_rsb
.id
;
798 sb_bindex
= subbuffer_id_get_index(config
, id
);
799 rpages
= bufb
->array
[sb_bindex
];
800 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
801 && subbuffer_id_is_noref(config
, id
));
802 *virt
= &rpages
->p
[index
].virt
;
803 return &rpages
->p
[index
].page
;
805 EXPORT_SYMBOL_GPL(lib_ring_buffer_read_get_page
);
808 * lib_ring_buffer_read_offset_address - get address of a buffer location
809 * @bufb : buffer backend
810 * @offset : offset within the buffer.
812 * Return the address where a given offset is located (for read).
813 * Should be used to get the current subbuffer header pointer. Given we know
814 * it's never on a page boundary, it's safe to write directly to this address,
815 * as long as the write is never bigger than a page size.
817 void *lib_ring_buffer_read_offset_address(struct lib_ring_buffer_backend
*bufb
,
821 struct lib_ring_buffer_backend_pages
*rpages
;
822 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
823 const struct lib_ring_buffer_config
*config
= &chanb
->config
;
824 unsigned long sb_bindex
, id
;
826 offset
&= chanb
->buf_size
- 1;
827 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
828 id
= bufb
->buf_rsb
.id
;
829 sb_bindex
= subbuffer_id_get_index(config
, id
);
830 rpages
= bufb
->array
[sb_bindex
];
831 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
832 && subbuffer_id_is_noref(config
, id
));
833 return rpages
->p
[index
].virt
+ (offset
& ~PAGE_MASK
);
835 EXPORT_SYMBOL_GPL(lib_ring_buffer_read_offset_address
);
838 * lib_ring_buffer_offset_address - get address of a location within the buffer
839 * @bufb : buffer backend
840 * @offset : offset within the buffer.
842 * Return the address where a given offset is located.
843 * Should be used to get the current subbuffer header pointer. Given we know
844 * it's always at the beginning of a page, it's safe to write directly to this
845 * address, as long as the write is never bigger than a page size.
847 void *lib_ring_buffer_offset_address(struct lib_ring_buffer_backend
*bufb
,
851 struct lib_ring_buffer_backend_pages
*rpages
;
852 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
853 const struct lib_ring_buffer_config
*config
= &chanb
->config
;
854 unsigned long sb_bindex
, id
;
856 offset
&= chanb
->buf_size
- 1;
857 sbidx
= offset
>> chanb
->subbuf_size_order
;
858 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
859 id
= bufb
->buf_wsb
[sbidx
].id
;
860 sb_bindex
= subbuffer_id_get_index(config
, id
);
861 rpages
= bufb
->array
[sb_bindex
];
862 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
863 && subbuffer_id_is_noref(config
, id
));
864 return rpages
->p
[index
].virt
+ (offset
& ~PAGE_MASK
);
866 EXPORT_SYMBOL_GPL(lib_ring_buffer_offset_address
);