X-Git-Url: https://git.lttng.org/?a=blobdiff_plain;f=src%2Flibringbuffer%2Fring_buffer_backend.c;fp=src%2Flibringbuffer%2Fring_buffer_backend.c;h=6ba0d8b1d44fe4fbb4dbe8989e773a355691c4d2;hb=9d4c8b2d907edb9ebc9bfde55602598e7ba0832e;hp=0000000000000000000000000000000000000000;hpb=6ba6fd60507f8e045bdc4f1be14e9d99c6a15f7f;p=lttng-ust.git diff --git a/src/libringbuffer/ring_buffer_backend.c b/src/libringbuffer/ring_buffer_backend.c new file mode 100644 index 00000000..6ba0d8b1 --- /dev/null +++ b/src/libringbuffer/ring_buffer_backend.c @@ -0,0 +1,593 @@ +/* + * SPDX-License-Identifier: LGPL-2.1-only + * + * Copyright (C) 2005-2012 Mathieu Desnoyers + */ + +#define _LGPL_SOURCE +#include +#include +#include +#include +#include + +#include +#include + +#include "ringbuffer-config.h" +#include "vatomic.h" +#include "backend.h" +#include "frontend.h" +#include "smp.h" +#include "shm.h" +#include "ust-compat.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)); +}