/*
* ring_buffer_backend.c
*
* Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; only
* version 2.1 of the License.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#define _GNU_SOURCE
#include <unistd.h>
#include <urcu/arch.h>
#include <limits.h>
#include <lttng/ringbuffer-config.h>
#include "vatomic.h"
#include "backend.h"
#include "frontend.h"
#include "smp.h"
#include "shm.h"
/**
* lib_ring_buffer_backend_allocate - allocate a channel buffer
* @config: ring buffer instance configuration
* @buf: the buffer struct
* @size: total size of the buffer
* @num_subbuf: number of subbuffers
* @extra_reader_sb: need extra subbuffer for reader
*/
static
int lib_ring_buffer_backend_allocate(const struct lttng_ust_lib_ring_buffer_config *config,
struct lttng_ust_lib_ring_buffer_backend *bufb,
size_t size, size_t num_subbuf,
int extra_reader_sb,
struct lttng_ust_shm_handle *handle,
struct shm_object *shmobj)
{
struct channel_backend *chanb;
unsigned long subbuf_size, mmap_offset = 0;
unsigned long num_subbuf_alloc;
unsigned long i;
long page_size;
chanb = &shmp(handle, bufb->chan)->backend;
if (!chanb)
return -EINVAL;
subbuf_size = chanb->subbuf_size;
num_subbuf_alloc = num_subbuf;
if (extra_reader_sb)
num_subbuf_alloc++;
page_size = sysconf(_SC_PAGE_SIZE);
if (page_size <= 0) {
goto page_size_error;
}
align_shm(shmobj, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages_shmp));
set_shmp(bufb->array, zalloc_shm(shmobj,
sizeof(struct lttng_ust_lib_ring_buffer_backend_pages_shmp) * num_subbuf_alloc));
if (caa_unlikely(!shmp(handle, bufb->array)))
goto array_error;
/*
* This is the largest element (the buffer pages) which needs to
* be aligned on page size.
*/
align_shm(shmobj, page_size);
set_shmp(bufb->memory_map, zalloc_shm(shmobj,
subbuf_size * num_subbuf_alloc));
if (caa_unlikely(!shmp(handle, bufb->memory_map)))
goto memory_map_error;
/* Allocate backend pages array elements */
for (i = 0; i < num_subbuf_alloc; i++) {
align_shm(shmobj, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages));
set_shmp(shmp_index(handle, bufb->array, i)->shmp,
zalloc_shm(shmobj,
sizeof(struct lttng_ust_lib_ring_buffer_backend_pages)));
if (!shmp(handle, shmp_index(handle, bufb->array, i)->shmp))
goto free_array;
}
/* Allocate write-side subbuffer table */
align_shm(shmobj, __alignof__(struct lttng_ust_lib_ring_buffer_backend_subbuffer));
set_shmp(bufb->buf_wsb, zalloc_shm(shmobj,
sizeof(struct lttng_ust_lib_ring_buffer_backend_subbuffer)
* num_subbuf));
if (caa_unlikely(!shmp(handle, bufb->buf_wsb)))
goto free_array;
for (i = 0; i < num_subbuf; i++) {
struct lttng_ust_lib_ring_buffer_backend_subbuffer *sb;
sb = shmp_index(handle, bufb->buf_wsb, i);
if (!sb)
goto free_array;
sb->id = subbuffer_id(config, 0, 1, i);
}
/* Assign read-side subbuffer table */
if (extra_reader_sb)
bufb->buf_rsb.id = subbuffer_id(config, 0, 1,
num_subbuf_alloc - 1);
else
bufb->buf_rsb.id = subbuffer_id(config, 0, 1, 0);
/* Allocate subbuffer packet counter table */
align_shm(shmobj, __alignof__(struct lttng_ust_lib_ring_buffer_backend_subbuffer));
set_shmp(bufb->buf_cnt, zalloc_shm(shmobj,
sizeof(struct lttng_ust_lib_ring_buffer_backend_counts)
* num_subbuf));
if (caa_unlikely(!shmp(handle, bufb->buf_cnt)))
goto free_wsb;
/* Assign pages to page index */
for (i = 0; i < num_subbuf_alloc; i++) {
struct lttng_ust_lib_ring_buffer_backend_pages_shmp *sbp;
struct lttng_ust_lib_ring_buffer_backend_pages *pages;
struct shm_ref ref;
ref.index = bufb->memory_map._ref.index;
ref.offset = bufb->memory_map._ref.offset;
ref.offset += i * subbuf_size;
sbp = shmp_index(handle, bufb->array, i);
if (!sbp)
goto free_array;
pages = shmp(handle, sbp->shmp);
if (!pages)
goto free_array;
set_shmp(pages->p, ref);
if (config->output == RING_BUFFER_MMAP) {
pages->mmap_offset = mmap_offset;
mmap_offset += subbuf_size;
}
}
return 0;
free_wsb:
/* bufb->buf_wsb will be freed by shm teardown */
free_array:
/* bufb->array[i] will be freed by shm teardown */
memory_map_error:
/* bufb->array will be freed by shm teardown */
array_error:
page_size_error:
return -ENOMEM;
}
int lib_ring_buffer_backend_create(struct lttng_ust_lib_ring_buffer_backend *bufb,
struct channel_backend *chanb, int cpu,
struct lttng_ust_shm_handle *handle,
struct shm_object *shmobj)
{
const struct lttng_ust_lib_ring_buffer_config *config = &chanb->config;
set_shmp(bufb->chan, handle->chan._ref);
bufb->cpu = cpu;
return lib_ring_buffer_backend_allocate(config, bufb, chanb->buf_size,
chanb->num_subbuf,
chanb->extra_reader_sb,
handle, shmobj);
}
void lib_ring_buffer_backend_reset(struct lttng_ust_lib_ring_buffer_backend *bufb,
struct lttng_ust_shm_handle *handle)
{
struct channel_backend *chanb;
const struct lttng_ust_lib_ring_buffer_config *config;
unsigned long num_subbuf_alloc;
unsigned int i;
chanb = &shmp(handle, bufb->chan)->backend;
if (!chanb)
abort();
config = &chanb->config;
num_subbuf_alloc = chanb->num_subbuf;
if (chanb->extra_reader_sb)
num_subbuf_alloc++;
for (i = 0; i < chanb->num_subbuf; i++) {
struct lttng_ust_lib_ring_buffer_backend_subbuffer *sb;
sb = shmp_index(handle, bufb->buf_wsb, i);
if (!sb)
abort();
sb->id = subbuffer_id(config, 0, 1, i);
}
if (chanb->extra_reader_sb)
bufb->buf_rsb.id = subbuffer_id(config, 0, 1,
num_subbuf_alloc - 1);
else
bufb->buf_rsb.id = subbuffer_id(config, 0, 1, 0);
for (i = 0; i < num_subbuf_alloc; i++) {
struct lttng_ust_lib_ring_buffer_backend_pages_shmp *sbp;
struct lttng_ust_lib_ring_buffer_backend_pages *pages;
sbp = shmp_index(handle, bufb->array, i);
if (!sbp)
abort();
pages = shmp(handle, sbp->shmp);
if (!pages)
abort();
/* Don't reset mmap_offset */
v_set(config, &pages->records_commit, 0);
v_set(config, &pages->records_unread, 0);
pages->data_size = 0;
/* Don't reset backend page and virt addresses */
}
/* Don't reset num_pages_per_subbuf, cpu, allocated */
v_set(config, &bufb->records_read, 0);
}
/*
* The frontend is responsible for also calling ring_buffer_backend_reset for
* each buffer when calling channel_backend_reset.
*/
void channel_backend_reset(struct channel_backend *chanb)
{
struct channel *chan = caa_container_of(chanb, struct channel, backend);
const struct lttng_ust_lib_ring_buffer_config *config = &chanb->config;
/*
* Don't reset buf_size, subbuf_size, subbuf_size_order,
* num_subbuf_order, buf_size_order, extra_reader_sb, num_subbuf,
* priv, notifiers, config, cpumask and name.
*/
chanb->start_tsc = config->cb.ring_buffer_clock_read(chan);
}
/**
* channel_backend_init - initialize a channel backend
* @chanb: channel backend
* @name: channel name
* @config: client ring buffer configuration
* @parent: dentry of parent directory, %NULL for root directory
* @subbuf_size: size of sub-buffers (> page size, power of 2)
* @num_subbuf: number of sub-buffers (power of 2)
* @lttng_ust_shm_handle: shared memory handle
* @stream_fds: stream file descriptors.
*
* Returns channel pointer if successful, %NULL otherwise.
*
* Creates per-cpu channel buffers using the sizes and attributes
* specified. The created channel buffer files will be named
* name_0...name_N-1. File permissions will be %S_IRUSR.
*
* Called with CPU hotplug disabled.
*/
int channel_backend_init(struct channel_backend *chanb,
const char *name,
const struct lttng_ust_lib_ring_buffer_config *config,
size_t subbuf_size, size_t num_subbuf,
struct lttng_ust_shm_handle *handle,
const int *stream_fds)
{
struct channel *chan = caa_container_of(chanb, struct channel, backend);
unsigned int i;
int ret;
size_t shmsize = 0, num_subbuf_alloc;
long page_size;
if (!name)
return -EPERM;
page_size = sysconf(_SC_PAGE_SIZE);
if (page_size <= 0) {
return -ENOMEM;
}
/* Check that the subbuffer size is larger than a page. */
if (subbuf_size < page_size)
return -EINVAL;
/*
* Make sure the number of subbuffers and subbuffer size are
* power of 2, and nonzero.
*/
if (!subbuf_size || (subbuf_size & (subbuf_size - 1)))
return -EINVAL;
if (!num_subbuf || (num_subbuf & (num_subbuf - 1)))
return -EINVAL;
/*
* Overwrite mode buffers require at least 2 subbuffers per
* buffer.
*/
if (config->mode == RING_BUFFER_OVERWRITE && num_subbuf < 2)
return -EINVAL;
ret = subbuffer_id_check_index(config, num_subbuf);
if (ret)
return ret;
chanb->buf_size = num_subbuf * subbuf_size;
chanb->subbuf_size = subbuf_size;
chanb->buf_size_order = get_count_order(chanb->buf_size);
chanb->subbuf_size_order = get_count_order(subbuf_size);
chanb->num_subbuf_order = get_count_order(num_subbuf);
chanb->extra_reader_sb =
(config->mode == RING_BUFFER_OVERWRITE) ? 1 : 0;
chanb->num_subbuf = num_subbuf;
strncpy(chanb->name, name, NAME_MAX);
chanb->name[NAME_MAX - 1] = '\0';
memcpy(&chanb->config, config, sizeof(*config));
/* Per-cpu buffer size: control (prior to backend) */
shmsize = offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer));
shmsize += sizeof(struct lttng_ust_lib_ring_buffer);
/* Per-cpu buffer size: backend */
/* num_subbuf + 1 is the worse case */
num_subbuf_alloc = num_subbuf + 1;
shmsize += offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages_shmp));
shmsize += sizeof(struct lttng_ust_lib_ring_buffer_backend_pages_shmp) * num_subbuf_alloc;
shmsize += offset_align(shmsize, page_size);
shmsize += subbuf_size * num_subbuf_alloc;
shmsize += offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages));
shmsize += sizeof(struct lttng_ust_lib_ring_buffer_backend_pages) * num_subbuf_alloc;
shmsize += offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer_backend_subbuffer));
shmsize += sizeof(struct lttng_ust_lib_ring_buffer_backend_subbuffer) * num_subbuf;
/* Per-cpu buffer size: control (after backend) */
shmsize += offset_align(shmsize, __alignof__(struct commit_counters_hot));
shmsize += sizeof(struct commit_counters_hot) * num_subbuf;
shmsize += offset_align(shmsize, __alignof__(struct commit_counters_cold));
shmsize += sizeof(struct commit_counters_cold) * num_subbuf;
if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
struct lttng_ust_lib_ring_buffer *buf;
/*
* We need to allocate for all possible cpus.
*/
for_each_possible_cpu(i) {
struct shm_object *shmobj;
shmobj = shm_object_table_alloc(handle->table, shmsize,
SHM_OBJECT_SHM, stream_fds[i]);
if (!shmobj)
goto end;
align_shm(shmobj, __alignof__(struct lttng_ust_lib_ring_buffer));
set_shmp(chanb->buf[i].shmp, zalloc_shm(shmobj, sizeof(struct lttng_ust_lib_ring_buffer)));
buf = shmp(handle, chanb->buf[i].shmp);
if (!buf)
goto end;
set_shmp(buf->self, chanb->buf[i].shmp._ref);
ret = lib_ring_buffer_create(buf, chanb, i,
handle, shmobj);
if (ret)
goto free_bufs; /* cpu hotplug locked */
}
} else {
struct shm_object *shmobj;
struct lttng_ust_lib_ring_buffer *buf;
shmobj = shm_object_table_alloc(handle->table, shmsize,
SHM_OBJECT_SHM, stream_fds[0]);
if (!shmobj)
goto end;
align_shm(shmobj, __alignof__(struct lttng_ust_lib_ring_buffer));
set_shmp(chanb->buf[0].shmp, zalloc_shm(shmobj, sizeof(struct lttng_ust_lib_ring_buffer)));
buf = shmp(handle, chanb->buf[0].shmp);
if (!buf)
goto end;
set_shmp(buf->self, chanb->buf[0].shmp._ref);
ret = lib_ring_buffer_create(buf, chanb, -1,
handle, shmobj);
if (ret)
goto free_bufs;
}
chanb->start_tsc = config->cb.ring_buffer_clock_read(chan);
return 0;
free_bufs:
/* We only free the buffer data upon shm teardown */
end:
return -ENOMEM;
}
/**
* channel_backend_free - destroy the channel
* @chan: the channel
*
* Destroy all channel buffers and frees the channel.
*/
void channel_backend_free(struct channel_backend *chanb,
struct lttng_ust_shm_handle *handle)
{
/* SHM teardown takes care of everything */
}
/**
* lib_ring_buffer_read - read data from ring_buffer_buffer.
* @bufb : buffer backend
* @offset : offset within the buffer
* @dest : destination address
* @len : length to copy to destination
*
* Should be protected by get_subbuf/put_subbuf.
* Returns the length copied.
*/
size_t lib_ring_buffer_read(struct lttng_ust_lib_ring_buffer_backend *bufb, size_t offset,
void *dest, size_t len, struct lttng_ust_shm_handle *handle)
{
struct channel_backend *chanb;
const struct lttng_ust_lib_ring_buffer_config *config;
ssize_t orig_len;
struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
unsigned long sb_bindex, id;
void *src;
chanb = &shmp(handle, bufb->chan)->backend;
if (!chanb)
return 0;
config = &chanb->config;
orig_len = len;
offset &= chanb->buf_size - 1;
if (caa_unlikely(!len))
return 0;
id = bufb->buf_rsb.id;
sb_bindex = subbuffer_id_get_index(config, id);
rpages = shmp_index(handle, bufb->array, sb_bindex);
/*
* Underlying layer should never ask for reads across
* subbuffers.
*/
CHAN_WARN_ON(chanb, offset >= chanb->buf_size);
CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE
&& subbuffer_id_is_noref(config, id));
src = shmp_index(handle, shmp(handle, rpages->shmp)->p,
offset & (chanb->subbuf_size - 1));
if (caa_unlikely(!src))
return 0;
memcpy(dest, src, len);
return orig_len;
}
/**
* lib_ring_buffer_read_cstr - read a C-style string from ring_buffer.
* @bufb : buffer backend
* @offset : offset within the buffer
* @dest : destination address
* @len : destination's length
*
* Return string's length, or -EINVAL on error.
* Should be protected by get_subbuf/put_subbuf.
* Destination length should be at least 1 to hold '\0'.
*/
int lib_ring_buffer_read_cstr(struct lttng_ust_lib_ring_buffer_backend *bufb, size_t offset,
void *dest, size_t len, struct lttng_ust_shm_handle *handle)
{
struct channel_backend *chanb;
const struct lttng_ust_lib_ring_buffer_config *config;
ssize_t string_len, orig_offset;
char *str;
struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
unsigned long sb_bindex, id;
chanb = &shmp(handle, bufb->chan)->backend;
if (!chanb)
return -EINVAL;
config = &chanb->config;
if (caa_unlikely(!len))
return -EINVAL;
offset &= chanb->buf_size - 1;
orig_offset = offset;
id = bufb->buf_rsb.id;
sb_bindex = subbuffer_id_get_index(config, id);
rpages = shmp_index(handle, bufb->array, sb_bindex);
/*
* Underlying layer should never ask for reads across
* subbuffers.
*/
CHAN_WARN_ON(chanb, offset >= chanb->buf_size);
CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE
&& subbuffer_id_is_noref(config, id));
str = shmp_index(handle, shmp(handle, rpages->shmp)->p, offset & (chanb->subbuf_size - 1));
if (caa_unlikely(!str))
return -EINVAL;
string_len = strnlen(str, len);
if (dest && len) {
memcpy(dest, str, string_len);
((char *)dest)[0] = 0;
}
return offset - orig_offset;
}
/**
* lib_ring_buffer_read_offset_address - get address of a buffer location
* @bufb : buffer backend
* @offset : offset within the buffer.
*
* Return the address where a given offset is located (for read).
* Should be used to get the current subbuffer header pointer. Given we know
* it's never on a page boundary, it's safe to read/write directly
* from/to this address, as long as the read/write is never bigger than
* a page size.
*/
void *lib_ring_buffer_read_offset_address(struct lttng_ust_lib_ring_buffer_backend *bufb,
size_t offset,
struct lttng_ust_shm_handle *handle)
{
struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
struct channel_backend *chanb;
const struct lttng_ust_lib_ring_buffer_config *config;
unsigned long sb_bindex, id;
chanb = &shmp(handle, bufb->chan)->backend;
if (!chanb)
return NULL;
config = &chanb->config;
offset &= chanb->buf_size - 1;
id = bufb->buf_rsb.id;
sb_bindex = subbuffer_id_get_index(config, id);
rpages = shmp_index(handle, bufb->array, sb_bindex);
CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE
&& subbuffer_id_is_noref(config, id));
return shmp_index(handle, shmp(handle, rpages->shmp)->p, offset & (chanb->subbuf_size - 1));
}
/**
* lib_ring_buffer_offset_address - get address of a location within the buffer
* @bufb : buffer backend
* @offset : offset within the buffer.
*
* Return the address where a given offset is located.
* Should be used to get the current subbuffer header pointer. Given we know
* it's always at the beginning of a page, it's safe to write directly to this
* address, as long as the write is never bigger than a page size.
*/
void *lib_ring_buffer_offset_address(struct lttng_ust_lib_ring_buffer_backend *bufb,
size_t offset,
struct lttng_ust_shm_handle *handle)
{
size_t sbidx;
struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
struct channel_backend *chanb;
const struct lttng_ust_lib_ring_buffer_config *config;
unsigned long sb_bindex, id;
struct lttng_ust_lib_ring_buffer_backend_subbuffer *sb;
chanb = &shmp(handle, bufb->chan)->backend;
if (!chanb)
return NULL;
config = &chanb->config;
offset &= chanb->buf_size - 1;
sbidx = offset >> chanb->subbuf_size_order;
sb = shmp_index(handle, bufb->buf_wsb, sbidx);
if (!sb)
return NULL;
id = sb->id;
sb_bindex = subbuffer_id_get_index(config, id);
rpages = shmp_index(handle, bufb->array, sb_bindex);
CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE
&& subbuffer_id_is_noref(config, id));
return shmp_index(handle, shmp(handle, rpages->shmp)->p, offset & (chanb->subbuf_size - 1));
}