--- /dev/null
+/*
+ * SPDX-License-Identifier: LGPL-2.1-only
+ *
+ * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ */
+
+#define _LGPL_SOURCE
+#include <stddef.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <urcu/arch.h>
+#include <limits.h>
+
+#include <lttng/ust-utils.h>
+#include <lttng/ringbuffer-context.h>
+
+#include "ringbuffer-config.h"
+#include "vatomic.h"
+#include "backend.h"
+#include "frontend.h"
+#include "smp.h"
+#include "shm.h"
+#include "common/align.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 __attribute__((unused)), 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 = LTTNG_UST_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_counts));
+ 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)
+ return;
+ 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)
+ return;
+ 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)
+ return;
+ pages = shmp(handle, sbp->shmp);
+ if (!pages)
+ return;
+ /* 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 lttng_ust_lib_ring_buffer_channel *chan = caa_container_of(chanb,
+ struct lttng_ust_lib_ring_buffer_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 lttng_ust_lib_ring_buffer_channel *chan = caa_container_of(chanb,
+ struct lttng_ust_lib_ring_buffer_channel, backend);
+ unsigned int i;
+ int ret;
+ size_t shmsize = 0, num_subbuf_alloc;
+ long page_size;
+
+ if (!name)
+ return -EPERM;
+
+ page_size = LTTNG_UST_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 = lttng_ust_offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer));
+ shmsize += sizeof(struct lttng_ust_lib_ring_buffer);
+ shmsize += lttng_ust_offset_align(shmsize, __alignof__(struct commit_counters_hot));
+ shmsize += sizeof(struct commit_counters_hot) * num_subbuf;
+ shmsize += lttng_ust_offset_align(shmsize, __alignof__(struct commit_counters_cold));
+ shmsize += sizeof(struct commit_counters_cold) * num_subbuf;
+ /* Sampled timestamp end */
+ shmsize += lttng_ust_offset_align(shmsize, __alignof__(uint64_t));
+ shmsize += sizeof(uint64_t) * num_subbuf;
+
+ /* Per-cpu buffer size: backend */
+ /* num_subbuf + 1 is the worse case */
+ num_subbuf_alloc = num_subbuf + 1;
+ shmsize += lttng_ust_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 += lttng_ust_offset_align(shmsize, page_size);
+ shmsize += subbuf_size * num_subbuf_alloc;
+ shmsize += lttng_ust_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 += lttng_ust_offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer_backend_subbuffer));
+ shmsize += sizeof(struct lttng_ust_lib_ring_buffer_backend_subbuffer) * num_subbuf;
+ shmsize += lttng_ust_offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer_backend_counts));
+ shmsize += sizeof(struct lttng_ust_lib_ring_buffer_backend_counts) * 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], 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], -1);
+ 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 __attribute__((unused)),
+ struct lttng_ust_shm_handle *handle __attribute__((unused)))
+{
+ /* 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;
+ struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
+ 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);
+ if (!rpages)
+ return 0;
+ /*
+ * 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));
+ backend_pages = shmp(handle, rpages->shmp);
+ if (!backend_pages)
+ return 0;
+ src = shmp_index(handle, backend_pages->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;
+ struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
+ 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);
+ if (!rpages)
+ return -EINVAL;
+ /*
+ * 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));
+ backend_pages = shmp(handle, rpages->shmp);
+ if (!backend_pages)
+ return -EINVAL;
+ str = shmp_index(handle, backend_pages->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 lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
+ 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);
+ if (!rpages)
+ return NULL;
+ CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE
+ && subbuffer_id_is_noref(config, id));
+ backend_pages = shmp(handle, rpages->shmp);
+ if (!backend_pages)
+ return NULL;
+ return shmp_index(handle, backend_pages->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 lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
+ 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);
+ if (!rpages)
+ return NULL;
+ CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE
+ && subbuffer_id_is_noref(config, id));
+ backend_pages = shmp(handle, rpages->shmp);
+ if (!backend_pages)
+ return NULL;
+ return shmp_index(handle, backend_pages->p, offset & (chanb->subbuf_size - 1));
+}
projects / lttng-ust.git / blobdiff