1 /* SPDX-License-Identifier: (GPL-2.0-only OR LGPL-2.1-only)
3 * ring_buffer_backend.c
5 * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
8 #include <linux/stddef.h>
9 #include <linux/module.h>
10 #include <linux/string.h>
11 #include <linux/bitops.h>
12 #include <linux/delay.h>
13 #include <linux/errno.h>
14 #include <linux/slab.h>
15 #include <linux/cpu.h>
17 #include <linux/vmalloc.h>
19 #include <wrapper/mm.h>
20 #include <wrapper/vmalloc.h> /* for wrapper_vmalloc_sync_mappings() */
21 #include <ringbuffer/config.h>
22 #include <ringbuffer/backend.h>
23 #include <ringbuffer/frontend.h>
26 * lib_ring_buffer_backend_allocate - allocate a channel buffer
27 * @config: ring buffer instance configuration
28 * @buf: the buffer struct
29 * @size: total size of the buffer
30 * @num_subbuf: number of subbuffers
31 * @extra_reader_sb: need extra subbuffer for reader
34 int lib_ring_buffer_backend_allocate(const struct lttng_kernel_ring_buffer_config
*config
,
35 struct lttng_kernel_ring_buffer_backend
*bufb
,
36 size_t size
, size_t num_subbuf
,
39 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
40 unsigned long j
, num_pages
, num_pages_per_subbuf
, page_idx
= 0;
41 unsigned long subbuf_size
, mmap_offset
= 0;
42 unsigned long num_subbuf_alloc
;
46 num_pages
= size
>> PAGE_SHIFT
;
49 * Verify that there is enough free pages available on the system for
50 * the current allocation request.
51 * wrapper_check_enough_free_pages uses si_mem_available() if available
52 * and returns if there should be enough free pages based on the
55 if (!wrapper_check_enough_free_pages(num_pages
))
56 goto not_enough_pages
;
59 * Set the current user thread as the first target of the OOM killer.
60 * If the estimate received by si_mem_available() was off, and we do
61 * end up running out of memory because of this buffer allocation, we
62 * want to kill the offending app first.
64 wrapper_set_current_oom_origin();
66 num_pages_per_subbuf
= num_pages
>> get_count_order(num_subbuf
);
67 subbuf_size
= chanb
->subbuf_size
;
68 num_subbuf_alloc
= num_subbuf
;
70 if (extra_reader_sb
) {
71 num_pages
+= num_pages_per_subbuf
; /* Add pages for reader */
75 pages
= vmalloc_node(ALIGN(sizeof(*pages
) * num_pages
,
76 1 << INTERNODE_CACHE_SHIFT
),
77 cpu_to_node(max(bufb
->cpu
, 0)));
81 bufb
->array
= lttng_kvmalloc_node(ALIGN(sizeof(*bufb
->array
)
83 1 << INTERNODE_CACHE_SHIFT
),
84 GFP_KERNEL
| __GFP_NOWARN
,
85 cpu_to_node(max(bufb
->cpu
, 0)));
86 if (unlikely(!bufb
->array
))
89 for (i
= 0; i
< num_pages
; i
++) {
90 pages
[i
] = alloc_pages_node(cpu_to_node(max(bufb
->cpu
, 0)),
91 GFP_KERNEL
| __GFP_NOWARN
| __GFP_ZERO
, 0);
92 if (unlikely(!pages
[i
]))
95 bufb
->num_pages_per_subbuf
= num_pages_per_subbuf
;
97 /* Allocate backend pages array elements */
98 for (i
= 0; i
< num_subbuf_alloc
; i
++) {
100 lttng_kvzalloc_node(ALIGN(
101 sizeof(struct lttng_kernel_ring_buffer_backend_pages
) +
102 sizeof(struct lttng_kernel_ring_buffer_backend_page
)
103 * num_pages_per_subbuf
,
104 1 << INTERNODE_CACHE_SHIFT
),
105 GFP_KERNEL
| __GFP_NOWARN
,
106 cpu_to_node(max(bufb
->cpu
, 0)));
111 /* Allocate write-side subbuffer table */
112 bufb
->buf_wsb
= lttng_kvzalloc_node(ALIGN(
113 sizeof(struct lttng_kernel_ring_buffer_backend_subbuffer
)
115 1 << INTERNODE_CACHE_SHIFT
),
116 GFP_KERNEL
| __GFP_NOWARN
,
117 cpu_to_node(max(bufb
->cpu
, 0)));
118 if (unlikely(!bufb
->buf_wsb
))
121 for (i
= 0; i
< num_subbuf
; i
++)
122 bufb
->buf_wsb
[i
].id
= subbuffer_id(config
, 0, 1, i
);
124 /* Assign read-side subbuffer table */
126 bufb
->buf_rsb
.id
= subbuffer_id(config
, 0, 1,
127 num_subbuf_alloc
- 1);
129 bufb
->buf_rsb
.id
= subbuffer_id(config
, 0, 1, 0);
131 /* Allocate subbuffer packet counter table */
132 bufb
->buf_cnt
= lttng_kvzalloc_node(ALIGN(
133 sizeof(struct lttng_kernel_ring_buffer_backend_counts
)
135 1 << INTERNODE_CACHE_SHIFT
),
136 GFP_KERNEL
| __GFP_NOWARN
,
137 cpu_to_node(max(bufb
->cpu
, 0)));
138 if (unlikely(!bufb
->buf_cnt
))
141 /* Assign pages to page index */
142 for (i
= 0; i
< num_subbuf_alloc
; i
++) {
143 for (j
= 0; j
< num_pages_per_subbuf
; j
++) {
144 CHAN_WARN_ON(chanb
, page_idx
> num_pages
);
145 bufb
->array
[i
]->p
[j
].virt
= page_address(pages
[page_idx
]);
146 bufb
->array
[i
]->p
[j
].pfn
= page_to_pfn(pages
[page_idx
]);
149 if (config
->output
== RING_BUFFER_MMAP
) {
150 bufb
->array
[i
]->mmap_offset
= mmap_offset
;
151 mmap_offset
+= subbuf_size
;
156 * If kmalloc ever uses vmalloc underneath, make sure the buffer pages
159 wrapper_vmalloc_sync_mappings();
160 wrapper_clear_current_oom_origin();
165 lttng_kvfree(bufb
->buf_wsb
);
167 for (i
= 0; (i
< num_subbuf_alloc
&& bufb
->array
[i
]); i
++)
168 lttng_kvfree(bufb
->array
[i
]);
170 /* Free all allocated pages */
171 for (i
= 0; (i
< num_pages
&& pages
[i
]); i
++)
172 __free_page(pages
[i
]);
173 lttng_kvfree(bufb
->array
);
177 wrapper_clear_current_oom_origin();
182 int lib_ring_buffer_backend_create(struct lttng_kernel_ring_buffer_backend
*bufb
,
183 struct channel_backend
*chanb
, int cpu
)
185 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
187 bufb
->chan
= container_of(chanb
, struct lttng_kernel_ring_buffer_channel
, backend
);
190 return lib_ring_buffer_backend_allocate(config
, bufb
, chanb
->buf_size
,
192 chanb
->extra_reader_sb
);
195 void lib_ring_buffer_backend_free(struct lttng_kernel_ring_buffer_backend
*bufb
)
197 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
198 unsigned long i
, j
, num_subbuf_alloc
;
200 num_subbuf_alloc
= chanb
->num_subbuf
;
201 if (chanb
->extra_reader_sb
)
204 lttng_kvfree(bufb
->buf_wsb
);
205 lttng_kvfree(bufb
->buf_cnt
);
206 for (i
= 0; i
< num_subbuf_alloc
; i
++) {
207 for (j
= 0; j
< bufb
->num_pages_per_subbuf
; j
++)
208 __free_page(pfn_to_page(bufb
->array
[i
]->p
[j
].pfn
));
209 lttng_kvfree(bufb
->array
[i
]);
211 lttng_kvfree(bufb
->array
);
215 void lib_ring_buffer_backend_reset(struct lttng_kernel_ring_buffer_backend
*bufb
)
217 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
218 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
219 unsigned long num_subbuf_alloc
;
222 num_subbuf_alloc
= chanb
->num_subbuf
;
223 if (chanb
->extra_reader_sb
)
226 for (i
= 0; i
< chanb
->num_subbuf
; i
++)
227 bufb
->buf_wsb
[i
].id
= subbuffer_id(config
, 0, 1, i
);
228 if (chanb
->extra_reader_sb
)
229 bufb
->buf_rsb
.id
= subbuffer_id(config
, 0, 1,
230 num_subbuf_alloc
- 1);
232 bufb
->buf_rsb
.id
= subbuffer_id(config
, 0, 1, 0);
234 for (i
= 0; i
< num_subbuf_alloc
; i
++) {
235 /* Don't reset mmap_offset */
236 v_set(config
, &bufb
->array
[i
]->records_commit
, 0);
237 v_set(config
, &bufb
->array
[i
]->records_unread
, 0);
238 bufb
->array
[i
]->data_size
= 0;
239 /* Don't reset backend page and virt addresses */
241 /* Don't reset num_pages_per_subbuf, cpu, allocated */
242 v_set(config
, &bufb
->records_read
, 0);
246 * The frontend is responsible for also calling ring_buffer_backend_reset for
247 * each buffer when calling channel_backend_reset.
249 void channel_backend_reset(struct channel_backend
*chanb
)
251 struct lttng_kernel_ring_buffer_channel
*chan
= container_of(chanb
, struct lttng_kernel_ring_buffer_channel
, backend
);
252 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
255 * Don't reset buf_size, subbuf_size, subbuf_size_order,
256 * num_subbuf_order, buf_size_order, extra_reader_sb, num_subbuf,
257 * priv, notifiers, config, cpumask and name.
259 chanb
->start_tsc
= config
->cb
.ring_buffer_clock_read(chan
);
262 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0))
265 * No need to implement a "dead" callback to do a buffer switch here,
266 * because it will happen when tracing is stopped, or will be done by
267 * switch timer CPU DEAD callback.
268 * We don't free buffers when CPU go away, because it would make trace
269 * data vanish, which is unwanted.
271 int lttng_cpuhp_rb_backend_prepare(unsigned int cpu
,
272 struct lttng_cpuhp_node
*node
)
274 struct channel_backend
*chanb
= container_of(node
,
275 struct channel_backend
, cpuhp_prepare
);
276 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
277 struct lttng_kernel_ring_buffer
*buf
;
280 CHAN_WARN_ON(chanb
, config
->alloc
== RING_BUFFER_ALLOC_GLOBAL
);
282 buf
= per_cpu_ptr(chanb
->buf
, cpu
);
283 ret
= lib_ring_buffer_create(buf
, chanb
, cpu
);
286 "LTTng: ring_buffer_cpu_hp_callback: cpu %d "
287 "buffer creation failed\n", cpu
);
292 EXPORT_SYMBOL_GPL(lttng_cpuhp_rb_backend_prepare
);
294 #else /* #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0)) */
296 #ifdef CONFIG_HOTPLUG_CPU
299 * lib_ring_buffer_cpu_hp_callback - CPU hotplug callback
300 * @nb: notifier block
301 * @action: hotplug action to take
304 * Returns the success/failure of the operation. (%NOTIFY_OK, %NOTIFY_BAD)
307 int lib_ring_buffer_cpu_hp_callback(struct notifier_block
*nb
,
308 unsigned long action
,
311 unsigned int cpu
= (unsigned long)hcpu
;
312 struct channel_backend
*chanb
= container_of(nb
, struct channel_backend
,
314 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
315 struct lttng_kernel_ring_buffer
*buf
;
318 CHAN_WARN_ON(chanb
, config
->alloc
== RING_BUFFER_ALLOC_GLOBAL
);
322 case CPU_UP_PREPARE_FROZEN
:
323 buf
= per_cpu_ptr(chanb
->buf
, cpu
);
324 ret
= lib_ring_buffer_create(buf
, chanb
, cpu
);
327 "LTTng: ring_buffer_cpu_hp_callback: cpu %d "
328 "buffer creation failed\n", cpu
);
333 case CPU_DEAD_FROZEN
:
334 /* No need to do a buffer switch here, because it will happen
335 * when tracing is stopped, or will be done by switch timer CPU
344 #endif /* #else #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0)) */
347 * channel_backend_init - initialize a channel backend
348 * @chanb: channel backend
349 * @name: channel name
350 * @config: client ring buffer configuration
351 * @priv: client private data
352 * @parent: dentry of parent directory, %NULL for root directory
353 * @subbuf_size: size of sub-buffers (> PAGE_SIZE, power of 2)
354 * @num_subbuf: number of sub-buffers (power of 2)
356 * Returns channel pointer if successful, %NULL otherwise.
358 * Creates per-cpu channel buffers using the sizes and attributes
359 * specified. The created channel buffer files will be named
360 * name_0...name_N-1. File permissions will be %S_IRUSR.
362 * Called with CPU hotplug disabled.
364 int channel_backend_init(struct channel_backend
*chanb
,
366 const struct lttng_kernel_ring_buffer_config
*config
,
367 void *priv
, size_t subbuf_size
, size_t num_subbuf
)
369 struct lttng_kernel_ring_buffer_channel
*chan
= container_of(chanb
, struct lttng_kernel_ring_buffer_channel
, backend
);
376 /* Check that the subbuffer size is larger than a page. */
377 if (subbuf_size
< PAGE_SIZE
)
381 * Make sure the number of subbuffers and subbuffer size are
382 * power of 2 and nonzero.
384 if (!subbuf_size
|| (subbuf_size
& (subbuf_size
- 1)))
386 if (!num_subbuf
|| (num_subbuf
& (num_subbuf
- 1)))
389 * Overwrite mode buffers require at least 2 subbuffers per
392 if (config
->mode
== RING_BUFFER_OVERWRITE
&& num_subbuf
< 2)
395 ret
= subbuffer_id_check_index(config
, num_subbuf
);
400 chanb
->buf_size
= num_subbuf
* subbuf_size
;
401 chanb
->subbuf_size
= subbuf_size
;
402 chanb
->buf_size_order
= get_count_order(chanb
->buf_size
);
403 chanb
->subbuf_size_order
= get_count_order(subbuf_size
);
404 chanb
->num_subbuf_order
= get_count_order(num_subbuf
);
405 chanb
->extra_reader_sb
=
406 (config
->mode
== RING_BUFFER_OVERWRITE
) ? 1 : 0;
407 chanb
->num_subbuf
= num_subbuf
;
408 strlcpy(chanb
->name
, name
, NAME_MAX
);
409 memcpy(&chanb
->config
, config
, sizeof(chanb
->config
));
411 if (config
->alloc
== RING_BUFFER_ALLOC_PER_CPU
) {
412 if (!zalloc_cpumask_var(&chanb
->cpumask
, GFP_KERNEL
))
416 if (config
->alloc
== RING_BUFFER_ALLOC_PER_CPU
) {
417 /* Allocating the buffer per-cpu structures */
418 chanb
->buf
= alloc_percpu(struct lttng_kernel_ring_buffer
);
422 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0))
423 chanb
->cpuhp_prepare
.component
= LTTNG_RING_BUFFER_BACKEND
;
424 ret
= cpuhp_state_add_instance(lttng_rb_hp_prepare
,
425 &chanb
->cpuhp_prepare
.node
);
428 #else /* #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0)) */
432 * In case of non-hotplug cpu, if the ring-buffer is allocated
433 * in early initcall, it will not be notified of secondary cpus.
434 * In that off case, we need to allocate for all possible cpus.
436 #ifdef CONFIG_HOTPLUG_CPU
438 * buf->backend.allocated test takes care of concurrent CPU
440 * Priority higher than frontend, so we create the ring buffer
441 * before we start the timer.
443 chanb
->cpu_hp_notifier
.notifier_call
=
444 lib_ring_buffer_cpu_hp_callback
;
445 chanb
->cpu_hp_notifier
.priority
= 5;
446 register_hotcpu_notifier(&chanb
->cpu_hp_notifier
);
449 for_each_online_cpu(i
) {
450 ret
= lib_ring_buffer_create(per_cpu_ptr(chanb
->buf
, i
),
453 goto free_bufs
; /* cpu hotplug locked */
457 for_each_possible_cpu(i
) {
458 ret
= lib_ring_buffer_create(per_cpu_ptr(chanb
->buf
, i
),
465 #endif /* #else #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0)) */
467 chanb
->buf
= kzalloc(sizeof(struct lttng_kernel_ring_buffer
), GFP_KERNEL
);
470 ret
= lib_ring_buffer_create(chanb
->buf
, chanb
, -1);
474 chanb
->start_tsc
= config
->cb
.ring_buffer_clock_read(chan
);
479 if (config
->alloc
== RING_BUFFER_ALLOC_PER_CPU
) {
480 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0))
482 * Teardown of lttng_rb_hp_prepare instance
483 * on "add" error is handled within cpu hotplug,
484 * no teardown to do from the caller.
486 #else /* #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0)) */
487 #ifdef CONFIG_HOTPLUG_CPU
489 unregister_hotcpu_notifier(&chanb
->cpu_hp_notifier
);
491 #endif /* #else #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0)) */
492 for_each_possible_cpu(i
) {
493 struct lttng_kernel_ring_buffer
*buf
=
494 per_cpu_ptr(chanb
->buf
, i
);
496 if (!buf
->backend
.allocated
)
498 lib_ring_buffer_free(buf
);
500 free_percpu(chanb
->buf
);
504 if (config
->alloc
== RING_BUFFER_ALLOC_PER_CPU
)
505 free_cpumask_var(chanb
->cpumask
);
510 * channel_backend_unregister_notifiers - unregister notifiers
515 void channel_backend_unregister_notifiers(struct channel_backend
*chanb
)
517 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
519 if (config
->alloc
== RING_BUFFER_ALLOC_PER_CPU
) {
520 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0))
523 ret
= cpuhp_state_remove_instance(lttng_rb_hp_prepare
,
524 &chanb
->cpuhp_prepare
.node
);
526 #else /* #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0)) */
527 unregister_hotcpu_notifier(&chanb
->cpu_hp_notifier
);
528 #endif /* #else #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,10,0)) */
533 * channel_backend_free - destroy the channel
536 * Destroy all channel buffers and frees the channel.
538 void channel_backend_free(struct channel_backend
*chanb
)
540 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
543 if (config
->alloc
== RING_BUFFER_ALLOC_PER_CPU
) {
544 for_each_possible_cpu(i
) {
545 struct lttng_kernel_ring_buffer
*buf
= per_cpu_ptr(chanb
->buf
, i
);
547 if (!buf
->backend
.allocated
)
549 lib_ring_buffer_free(buf
);
551 free_cpumask_var(chanb
->cpumask
);
552 free_percpu(chanb
->buf
);
554 struct lttng_kernel_ring_buffer
*buf
= chanb
->buf
;
556 CHAN_WARN_ON(chanb
, !buf
->backend
.allocated
);
557 lib_ring_buffer_free(buf
);
563 * lib_ring_buffer_write - write data to a ring_buffer buffer.
564 * @bufb : buffer backend
565 * @offset : offset within the buffer
566 * @src : source address
567 * @len : length to write
569 void _lib_ring_buffer_write(struct lttng_kernel_ring_buffer_backend
*bufb
, size_t offset
,
570 const void *src
, size_t len
)
572 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
573 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
574 size_t sbidx
, index
, bytes_left_in_page
;
575 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
576 unsigned long sb_bindex
, id
;
579 sbidx
= offset
>> chanb
->subbuf_size_order
;
580 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
583 * Underlying layer should never ask for writes across
586 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
588 bytes_left_in_page
= min_t(size_t, len
, PAGE_SIZE
- (offset
& ~PAGE_MASK
));
589 id
= bufb
->buf_wsb
[sbidx
].id
;
590 sb_bindex
= subbuffer_id_get_index(config
, id
);
591 rpages
= bufb
->array
[sb_bindex
];
592 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
593 && subbuffer_id_is_noref(config
, id
));
594 lib_ring_buffer_do_copy(config
,
595 rpages
->p
[index
].virt
596 + (offset
& ~PAGE_MASK
),
597 src
, bytes_left_in_page
);
598 len
-= bytes_left_in_page
;
599 src
+= bytes_left_in_page
;
600 offset
+= bytes_left_in_page
;
601 } while (unlikely(len
));
603 EXPORT_SYMBOL_GPL(_lib_ring_buffer_write
);
606 * lib_ring_buffer_memset - write len bytes of c to a ring_buffer buffer.
607 * @bufb : buffer backend
608 * @offset : offset within the buffer
609 * @c : the byte to write
610 * @len : length to write
612 void _lib_ring_buffer_memset(struct lttng_kernel_ring_buffer_backend
*bufb
,
613 size_t offset
, int c
, size_t len
)
615 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
616 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
617 size_t sbidx
, index
, bytes_left_in_page
;
618 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
619 unsigned long sb_bindex
, id
;
622 sbidx
= offset
>> chanb
->subbuf_size_order
;
623 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
626 * Underlying layer should never ask for writes across
629 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
631 bytes_left_in_page
= min_t(size_t, len
, PAGE_SIZE
- (offset
& ~PAGE_MASK
));
632 id
= bufb
->buf_wsb
[sbidx
].id
;
633 sb_bindex
= subbuffer_id_get_index(config
, id
);
634 rpages
= bufb
->array
[sb_bindex
];
635 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
636 && subbuffer_id_is_noref(config
, id
));
637 lib_ring_buffer_do_memset(rpages
->p
[index
].virt
638 + (offset
& ~PAGE_MASK
),
639 c
, bytes_left_in_page
);
640 len
-= bytes_left_in_page
;
641 offset
+= bytes_left_in_page
;
642 } while (unlikely(len
));
644 EXPORT_SYMBOL_GPL(_lib_ring_buffer_memset
);
647 * lib_ring_buffer_strcpy - write string data to a ring_buffer buffer.
648 * @bufb : buffer backend
649 * @offset : offset within the buffer
650 * @src : source address
651 * @len : length to write
652 * @pad : character to use for padding
654 void _lib_ring_buffer_strcpy(struct lttng_kernel_ring_buffer_backend
*bufb
,
655 size_t offset
, const char *src
, size_t len
, int pad
)
657 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
658 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
659 size_t sbidx
, index
, bytes_left_in_page
;
660 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
661 unsigned long sb_bindex
, id
;
662 bool src_terminated
= false;
664 CHAN_WARN_ON(chanb
, !len
);
666 sbidx
= offset
>> chanb
->subbuf_size_order
;
667 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
670 * Underlying layer should never ask for writes across
673 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
675 bytes_left_in_page
= min_t(size_t, len
, PAGE_SIZE
- (offset
& ~PAGE_MASK
));
676 id
= bufb
->buf_wsb
[sbidx
].id
;
677 sb_bindex
= subbuffer_id_get_index(config
, id
);
678 rpages
= bufb
->array
[sb_bindex
];
679 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
680 && subbuffer_id_is_noref(config
, id
));
682 if (likely(!src_terminated
)) {
683 size_t count
, to_copy
;
685 to_copy
= bytes_left_in_page
;
686 if (bytes_left_in_page
== len
)
687 to_copy
--; /* Final '\0' */
688 count
= lib_ring_buffer_do_strcpy(config
,
689 rpages
->p
[index
].virt
690 + (offset
& ~PAGE_MASK
),
694 if (unlikely(count
< to_copy
)) {
695 size_t pad_len
= to_copy
- count
;
697 /* Next pages will have padding */
698 src_terminated
= true;
699 lib_ring_buffer_do_memset(rpages
->p
[index
].virt
700 + (offset
& ~PAGE_MASK
),
707 pad_len
= bytes_left_in_page
;
708 if (bytes_left_in_page
== len
)
709 pad_len
--; /* Final '\0' */
710 lib_ring_buffer_do_memset(rpages
->p
[index
].virt
711 + (offset
& ~PAGE_MASK
),
715 len
-= bytes_left_in_page
;
717 src
+= bytes_left_in_page
;
718 } while (unlikely(len
));
721 lib_ring_buffer_do_memset(rpages
->p
[index
].virt
+ (offset
& ~PAGE_MASK
),
724 EXPORT_SYMBOL_GPL(_lib_ring_buffer_strcpy
);
727 * _lib_ring_buffer_pstrcpy - write to a buffer backend P-string
728 * @bufb : buffer backend
729 * @src : source pointer to copy from
730 * @len : length of data to copy
731 * @pad : character to use for padding
733 * This function copies up to @len bytes of data from a source pointer
734 * to a Pascal String into the buffer backend. If a terminating '\0'
735 * character is found in @src before @len characters are copied, pad the
736 * buffer with @pad characters (e.g. '\0').
738 * The length of the pascal strings in the ring buffer is explicit: it
739 * is either the array or sequence length.
741 void _lib_ring_buffer_pstrcpy(struct lttng_kernel_ring_buffer_backend
*bufb
,
742 size_t offset
, const char *src
, size_t len
, int pad
)
744 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
745 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
746 size_t sbidx
, index
, bytes_left_in_page
;
747 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
748 unsigned long sb_bindex
, id
;
749 bool src_terminated
= false;
751 CHAN_WARN_ON(chanb
, !len
);
753 sbidx
= offset
>> chanb
->subbuf_size_order
;
754 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
757 * Underlying layer should never ask for writes across
760 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
762 bytes_left_in_page
= min_t(size_t, len
, PAGE_SIZE
- (offset
& ~PAGE_MASK
));
763 id
= bufb
->buf_wsb
[sbidx
].id
;
764 sb_bindex
= subbuffer_id_get_index(config
, id
);
765 rpages
= bufb
->array
[sb_bindex
];
766 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
767 && subbuffer_id_is_noref(config
, id
));
769 if (likely(!src_terminated
)) {
770 size_t count
, to_copy
;
772 to_copy
= bytes_left_in_page
;
773 count
= lib_ring_buffer_do_strcpy(config
,
774 rpages
->p
[index
].virt
775 + (offset
& ~PAGE_MASK
),
779 if (unlikely(count
< to_copy
)) {
780 size_t pad_len
= to_copy
- count
;
782 /* Next pages will have padding */
783 src_terminated
= true;
784 lib_ring_buffer_do_memset(rpages
->p
[index
].virt
785 + (offset
& ~PAGE_MASK
),
792 pad_len
= bytes_left_in_page
;
793 lib_ring_buffer_do_memset(rpages
->p
[index
].virt
794 + (offset
& ~PAGE_MASK
),
798 len
-= bytes_left_in_page
;
800 src
+= bytes_left_in_page
;
801 } while (unlikely(len
));
803 EXPORT_SYMBOL_GPL(_lib_ring_buffer_pstrcpy
);
806 * lib_ring_buffer_copy_from_user_inatomic - write user data to a ring_buffer buffer.
807 * @bufb : buffer backend
808 * @offset : offset within the buffer
809 * @src : source address
810 * @len : length to write
812 * This function deals with userspace pointers, it should never be called
813 * directly without having the src pointer checked with access_ok()
816 void _lib_ring_buffer_copy_from_user_inatomic(struct lttng_kernel_ring_buffer_backend
*bufb
,
817 size_t offset
, const void __user
*src
, size_t len
)
819 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
820 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
821 size_t sbidx
, index
, bytes_left_in_page
;
822 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
823 unsigned long sb_bindex
, id
;
827 sbidx
= offset
>> chanb
->subbuf_size_order
;
828 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
831 * Underlying layer should never ask for writes across
834 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
836 bytes_left_in_page
= min_t(size_t, len
, PAGE_SIZE
- (offset
& ~PAGE_MASK
));
837 id
= bufb
->buf_wsb
[sbidx
].id
;
838 sb_bindex
= subbuffer_id_get_index(config
, id
);
839 rpages
= bufb
->array
[sb_bindex
];
840 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
841 && subbuffer_id_is_noref(config
, id
));
842 ret
= lib_ring_buffer_do_copy_from_user_inatomic(rpages
->p
[index
].virt
843 + (offset
& ~PAGE_MASK
),
844 src
, bytes_left_in_page
) != 0;
847 _lib_ring_buffer_memset(bufb
, offset
, 0, len
);
848 break; /* stop copy */
850 len
-= bytes_left_in_page
;
851 src
+= bytes_left_in_page
;
852 offset
+= bytes_left_in_page
;
853 } while (unlikely(len
));
855 EXPORT_SYMBOL_GPL(_lib_ring_buffer_copy_from_user_inatomic
);
858 * lib_ring_buffer_strcpy_from_user_inatomic - write userspace string data to a ring_buffer buffer.
859 * @bufb : buffer backend
860 * @offset : offset within the buffer
861 * @src : source address
862 * @len : length to write
863 * @pad : character to use for padding
865 * This function deals with userspace pointers, it should never be called
866 * directly without having the src pointer checked with access_ok()
869 void _lib_ring_buffer_strcpy_from_user_inatomic(struct lttng_kernel_ring_buffer_backend
*bufb
,
870 size_t offset
, const char __user
*src
, size_t len
, int pad
)
872 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
873 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
874 size_t sbidx
, index
, bytes_left_in_page
;
875 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
876 unsigned long sb_bindex
, id
;
877 bool src_terminated
= false;
880 sbidx
= offset
>> chanb
->subbuf_size_order
;
881 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
884 * Underlying layer should never ask for writes across
887 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
889 bytes_left_in_page
= min_t(size_t, len
, PAGE_SIZE
- (offset
& ~PAGE_MASK
));
890 id
= bufb
->buf_wsb
[sbidx
].id
;
891 sb_bindex
= subbuffer_id_get_index(config
, id
);
892 rpages
= bufb
->array
[sb_bindex
];
893 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
894 && subbuffer_id_is_noref(config
, id
));
896 if (likely(!src_terminated
)) {
897 size_t count
, to_copy
;
899 to_copy
= bytes_left_in_page
;
900 if (bytes_left_in_page
== len
)
901 to_copy
--; /* Final '\0' */
902 count
= lib_ring_buffer_do_strcpy_from_user_inatomic(config
,
903 rpages
->p
[index
].virt
904 + (offset
& ~PAGE_MASK
),
908 if (unlikely(count
< to_copy
)) {
909 size_t pad_len
= to_copy
- count
;
911 /* Next pages will have padding */
912 src_terminated
= true;
913 lib_ring_buffer_do_memset(rpages
->p
[index
].virt
914 + (offset
& ~PAGE_MASK
),
921 pad_len
= bytes_left_in_page
;
922 if (bytes_left_in_page
== len
)
923 pad_len
--; /* Final '\0' */
924 lib_ring_buffer_do_memset(rpages
->p
[index
].virt
925 + (offset
& ~PAGE_MASK
),
929 len
-= bytes_left_in_page
;
931 src
+= bytes_left_in_page
;
932 } while (unlikely(len
));
935 lib_ring_buffer_do_memset(rpages
->p
[index
].virt
+ (offset
& ~PAGE_MASK
),
938 EXPORT_SYMBOL_GPL(_lib_ring_buffer_strcpy_from_user_inatomic
);
941 * _lib_ring_buffer_pstrcpy_from_user_inatomic - write userspace string to a buffer backend P-string
942 * @bufb : buffer backend
943 * @src : source pointer to copy from
944 * @len : length of data to copy
945 * @pad : character to use for padding
947 * This function copies up to @len bytes of data from a source pointer
948 * to a Pascal String into the buffer backend. If a terminating '\0'
949 * character is found in @src before @len characters are copied, pad the
950 * buffer with @pad characters (e.g. '\0').
952 * The length of the pascal strings in the ring buffer is explicit: it
953 * is either the array or sequence length.
955 * This function deals with userspace pointers, it should never be called
956 * directly without having the src pointer checked with access_ok()
959 void _lib_ring_buffer_pstrcpy_from_user_inatomic(struct lttng_kernel_ring_buffer_backend
*bufb
,
960 size_t offset
, const char __user
*src
, size_t len
, int pad
)
962 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
963 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
964 size_t sbidx
, index
, bytes_left_in_page
;
965 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
966 unsigned long sb_bindex
, id
;
967 bool src_terminated
= false;
969 CHAN_WARN_ON(chanb
, !len
);
971 sbidx
= offset
>> chanb
->subbuf_size_order
;
972 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
975 * Underlying layer should never ask for writes across
978 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
980 bytes_left_in_page
= min_t(size_t, len
, PAGE_SIZE
- (offset
& ~PAGE_MASK
));
981 id
= bufb
->buf_wsb
[sbidx
].id
;
982 sb_bindex
= subbuffer_id_get_index(config
, id
);
983 rpages
= bufb
->array
[sb_bindex
];
984 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
985 && subbuffer_id_is_noref(config
, id
));
987 if (likely(!src_terminated
)) {
988 size_t count
, to_copy
;
990 to_copy
= bytes_left_in_page
;
991 count
= lib_ring_buffer_do_strcpy_from_user_inatomic(config
,
992 rpages
->p
[index
].virt
993 + (offset
& ~PAGE_MASK
),
997 if (unlikely(count
< to_copy
)) {
998 size_t pad_len
= to_copy
- count
;
1000 /* Next pages will have padding */
1001 src_terminated
= true;
1002 lib_ring_buffer_do_memset(rpages
->p
[index
].virt
1003 + (offset
& ~PAGE_MASK
),
1010 pad_len
= bytes_left_in_page
;
1011 lib_ring_buffer_do_memset(rpages
->p
[index
].virt
1012 + (offset
& ~PAGE_MASK
),
1016 len
-= bytes_left_in_page
;
1017 if (!src_terminated
)
1018 src
+= bytes_left_in_page
;
1019 } while (unlikely(len
));
1021 EXPORT_SYMBOL_GPL(_lib_ring_buffer_pstrcpy_from_user_inatomic
);
1024 * lib_ring_buffer_read - read data from ring_buffer_buffer.
1025 * @bufb : buffer backend
1026 * @offset : offset within the buffer
1027 * @dest : destination address
1028 * @len : length to copy to destination
1030 * Should be protected by get_subbuf/put_subbuf.
1031 * Returns the length copied.
1033 size_t lib_ring_buffer_read(struct lttng_kernel_ring_buffer_backend
*bufb
, size_t offset
,
1034 void *dest
, size_t len
)
1036 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
1037 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
1038 size_t index
, bytes_left_in_page
, orig_len
;
1039 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
1040 unsigned long sb_bindex
, id
;
1043 offset
&= chanb
->buf_size
- 1;
1044 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
1048 bytes_left_in_page
= min_t(size_t, len
, PAGE_SIZE
- (offset
& ~PAGE_MASK
));
1049 id
= bufb
->buf_rsb
.id
;
1050 sb_bindex
= subbuffer_id_get_index(config
, id
);
1051 rpages
= bufb
->array
[sb_bindex
];
1052 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
1053 && subbuffer_id_is_noref(config
, id
));
1054 memcpy(dest
, rpages
->p
[index
].virt
+ (offset
& ~PAGE_MASK
),
1055 bytes_left_in_page
);
1056 len
-= bytes_left_in_page
;
1059 dest
+= bytes_left_in_page
;
1060 offset
+= bytes_left_in_page
;
1061 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
1063 * Underlying layer should never ask for reads across
1066 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
1070 EXPORT_SYMBOL_GPL(lib_ring_buffer_read
);
1073 * __lib_ring_buffer_copy_to_user - read data from ring_buffer to userspace
1074 * @bufb : buffer backend
1075 * @offset : offset within the buffer
1076 * @dest : destination userspace address
1077 * @len : length to copy to destination
1079 * Should be protected by get_subbuf/put_subbuf.
1080 * access_ok() must have been performed on dest addresses prior to call this
1082 * Returns -EFAULT on error, 0 if ok.
1084 int __lib_ring_buffer_copy_to_user(struct lttng_kernel_ring_buffer_backend
*bufb
,
1085 size_t offset
, void __user
*dest
, size_t len
)
1087 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
1088 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
1090 ssize_t bytes_left_in_page
;
1091 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
1092 unsigned long sb_bindex
, id
;
1094 offset
&= chanb
->buf_size
- 1;
1095 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
1099 bytes_left_in_page
= min_t(size_t, len
, PAGE_SIZE
- (offset
& ~PAGE_MASK
));
1100 id
= bufb
->buf_rsb
.id
;
1101 sb_bindex
= subbuffer_id_get_index(config
, id
);
1102 rpages
= bufb
->array
[sb_bindex
];
1103 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
1104 && subbuffer_id_is_noref(config
, id
));
1105 if (__copy_to_user(dest
,
1106 rpages
->p
[index
].virt
+ (offset
& ~PAGE_MASK
),
1107 bytes_left_in_page
))
1109 len
-= bytes_left_in_page
;
1112 dest
+= bytes_left_in_page
;
1113 offset
+= bytes_left_in_page
;
1114 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
1116 * Underlying layer should never ask for reads across
1119 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
1123 EXPORT_SYMBOL_GPL(__lib_ring_buffer_copy_to_user
);
1126 * lib_ring_buffer_read_cstr - read a C-style string from ring_buffer.
1127 * @bufb : buffer backend
1128 * @offset : offset within the buffer
1129 * @dest : destination address
1130 * @len : destination's length
1132 * Return string's length, or -EINVAL on error.
1133 * Should be protected by get_subbuf/put_subbuf.
1134 * Destination length should be at least 1 to hold '\0'.
1136 int lib_ring_buffer_read_cstr(struct lttng_kernel_ring_buffer_backend
*bufb
, size_t offset
,
1137 void *dest
, size_t len
)
1139 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
1140 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
1142 ssize_t bytes_left_in_page
, pagelen
, strpagelen
, orig_offset
;
1144 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
1145 unsigned long sb_bindex
, id
;
1147 offset
&= chanb
->buf_size
- 1;
1148 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
1149 orig_offset
= offset
;
1153 id
= bufb
->buf_rsb
.id
;
1154 sb_bindex
= subbuffer_id_get_index(config
, id
);
1155 rpages
= bufb
->array
[sb_bindex
];
1156 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
1157 && subbuffer_id_is_noref(config
, id
));
1158 str
= (char *)rpages
->p
[index
].virt
+ (offset
& ~PAGE_MASK
);
1159 pagelen
= PAGE_SIZE
- (offset
& ~PAGE_MASK
);
1160 strpagelen
= strnlen(str
, pagelen
);
1162 bytes_left_in_page
= min_t(size_t, len
, strpagelen
);
1164 memcpy(dest
, str
, bytes_left_in_page
);
1165 dest
+= bytes_left_in_page
;
1167 len
-= bytes_left_in_page
;
1169 offset
+= strpagelen
;
1170 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
1171 if (strpagelen
< pagelen
)
1174 * Underlying layer should never ask for reads across
1177 CHAN_WARN_ON(chanb
, offset
>= chanb
->buf_size
);
1180 ((char *)dest
)[0] = 0;
1181 return offset
- orig_offset
;
1183 EXPORT_SYMBOL_GPL(lib_ring_buffer_read_cstr
);
1186 * lib_ring_buffer_read_get_pfn - Get a page frame number to read from
1187 * @bufb : buffer backend
1188 * @offset : offset within the buffer
1189 * @virt : pointer to page address (output)
1191 * Should be protected by get_subbuf/put_subbuf.
1192 * Returns the pointer to the page frame number unsigned long.
1194 unsigned long *lib_ring_buffer_read_get_pfn(struct lttng_kernel_ring_buffer_backend
*bufb
,
1195 size_t offset
, void ***virt
)
1198 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
1199 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
1200 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
1201 unsigned long sb_bindex
, id
;
1203 offset
&= chanb
->buf_size
- 1;
1204 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
1205 id
= bufb
->buf_rsb
.id
;
1206 sb_bindex
= subbuffer_id_get_index(config
, id
);
1207 rpages
= bufb
->array
[sb_bindex
];
1208 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
1209 && subbuffer_id_is_noref(config
, id
));
1210 *virt
= &rpages
->p
[index
].virt
;
1211 return &rpages
->p
[index
].pfn
;
1213 EXPORT_SYMBOL_GPL(lib_ring_buffer_read_get_pfn
);
1216 * lib_ring_buffer_read_offset_address - get address of a buffer location
1217 * @bufb : buffer backend
1218 * @offset : offset within the buffer.
1220 * Return the address where a given offset is located (for read).
1221 * Should be used to get the current subbuffer header pointer. Given we know
1222 * it's never on a page boundary, it's safe to read/write directly
1223 * from/to this address, as long as the read/write is never bigger than a
1226 void *lib_ring_buffer_read_offset_address(struct lttng_kernel_ring_buffer_backend
*bufb
,
1230 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
1231 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
1232 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
1233 unsigned long sb_bindex
, id
;
1235 offset
&= chanb
->buf_size
- 1;
1236 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
1237 id
= bufb
->buf_rsb
.id
;
1238 sb_bindex
= subbuffer_id_get_index(config
, id
);
1239 rpages
= bufb
->array
[sb_bindex
];
1240 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
1241 && subbuffer_id_is_noref(config
, id
));
1242 return rpages
->p
[index
].virt
+ (offset
& ~PAGE_MASK
);
1244 EXPORT_SYMBOL_GPL(lib_ring_buffer_read_offset_address
);
1247 * lib_ring_buffer_offset_address - get address of a location within the buffer
1248 * @bufb : buffer backend
1249 * @offset : offset within the buffer.
1251 * Return the address where a given offset is located.
1252 * Should be used to get the current subbuffer header pointer. Given we know
1253 * it's always at the beginning of a page, it's safe to write directly to this
1254 * address, as long as the write is never bigger than a page size.
1256 void *lib_ring_buffer_offset_address(struct lttng_kernel_ring_buffer_backend
*bufb
,
1259 size_t sbidx
, index
;
1260 struct lttng_kernel_ring_buffer_backend_pages
*rpages
;
1261 struct channel_backend
*chanb
= &bufb
->chan
->backend
;
1262 const struct lttng_kernel_ring_buffer_config
*config
= &chanb
->config
;
1263 unsigned long sb_bindex
, id
;
1265 offset
&= chanb
->buf_size
- 1;
1266 sbidx
= offset
>> chanb
->subbuf_size_order
;
1267 index
= (offset
& (chanb
->subbuf_size
- 1)) >> PAGE_SHIFT
;
1268 id
= bufb
->buf_wsb
[sbidx
].id
;
1269 sb_bindex
= subbuffer_id_get_index(config
, id
);
1270 rpages
= bufb
->array
[sb_bindex
];
1271 CHAN_WARN_ON(chanb
, config
->mode
== RING_BUFFER_OVERWRITE
1272 && subbuffer_id_is_noref(config
, id
));
1273 return rpages
->p
[index
].virt
+ (offset
& ~PAGE_MASK
);
1275 EXPORT_SYMBOL_GPL(lib_ring_buffer_offset_address
);