X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=libringbuffer%2Ffrontend_internal.h;h=c8a54e96a83cd52ed1f29877c1b98cd1871ced4e;hb=071dec4386ff4c89d8b0f92ab1a8dbf079abd50c;hp=4ad921ec0ec8263086cddbf1c11044110dc672f6;hpb=beca55a1aa4ff272188d7c37c19eb0540f811c8b;p=lttng-ust.git diff --git a/libringbuffer/frontend_internal.h b/libringbuffer/frontend_internal.h index 4ad921ec..c8a54e96 100644 --- a/libringbuffer/frontend_internal.h +++ b/libringbuffer/frontend_internal.h @@ -1,45 +1,27 @@ -#ifndef _LTTNG_RING_BUFFER_FRONTEND_INTERNAL_H -#define _LTTNG_RING_BUFFER_FRONTEND_INTERNAL_H - /* - * libringbuffer/frontend_internal.h - * - * Ring Buffer Library Synchronization Header (internal helpers). + * SPDX-License-Identifier: (LGPL-2.1-only or GPL-2.0-only) * * Copyright (C) 2005-2012 Mathieu Desnoyers * - * 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 - * - * - * Author: - * Mathieu Desnoyers + * Ring Buffer Library Synchronization Header (internal helpers). * * See ring_buffer_frontend.c for more information on wait-free algorithms. - * - * Dual LGPL v2.1/GPL v2 license. */ +#ifndef _LTTNG_RING_BUFFER_FRONTEND_INTERNAL_H +#define _LTTNG_RING_BUFFER_FRONTEND_INTERNAL_H + #include #include #include +#include #include #include #include "backend_types.h" #include "frontend_types.h" #include "shm.h" +#include "ust-helper.h" /* Buffer offset macros */ @@ -157,15 +139,18 @@ int last_tsc_overflow(const struct lttng_ust_lib_ring_buffer_config *config, } #endif +LTTNG_HIDDEN extern int lib_ring_buffer_reserve_slow(struct lttng_ust_lib_ring_buffer_ctx *ctx, void *client_ctx); +LTTNG_HIDDEN extern void lib_ring_buffer_switch_slow(struct lttng_ust_lib_ring_buffer *buf, enum switch_mode mode, struct lttng_ust_shm_handle *handle); +LTTNG_HIDDEN void lib_ring_buffer_check_deliver_slow(const struct lttng_ust_lib_ring_buffer_config *config, struct lttng_ust_lib_ring_buffer *buf, struct channel *chan, @@ -205,6 +190,15 @@ void lib_ring_buffer_reserve_push_reader(struct lttng_ust_lib_ring_buffer *buf, consumed_new) != consumed_old)); } +/* + * Move consumed position to the beginning of subbuffer in which the + * write offset is. Should only be used on ring buffers that are not + * actively being written into, because clear_reader does not take into + * account the commit counters when moving the consumed position, which + * can make concurrent trace producers or consumers observe consumed + * position further than the write offset, which breaks ring buffer + * algorithm guarantees. + */ static inline void lib_ring_buffer_clear_reader(struct lttng_ust_lib_ring_buffer *buf, struct lttng_ust_shm_handle *handle) @@ -221,12 +215,10 @@ void lib_ring_buffer_clear_reader(struct lttng_ust_lib_ring_buffer *buf, do { offset = v_read(config, &buf->offset); consumed_old = uatomic_read(&buf->consumed); - if (caa_unlikely(subbuf_trunc(offset, chan) - - subbuf_trunc(consumed_old, chan) - > 0)) - consumed_new = subbuf_trunc(offset, chan); - else - return; + CHAN_WARN_ON(chan, (long) (subbuf_trunc(offset, chan) + - subbuf_trunc(consumed_old, chan)) + < 0); + consumed_new = subbuf_trunc(offset, chan); } while (caa_unlikely(uatomic_cmpxchg(&buf->consumed, consumed_old, consumed_new) != consumed_old)); } @@ -260,14 +252,11 @@ int lib_ring_buffer_reserve_committed(const struct lttng_ust_lib_ring_buffer_con struct lttng_ust_shm_handle *handle) { unsigned long offset, idx, commit_count; - struct commit_counters_hot *cc_hot = shmp_index(handle, buf->commit_hot, idx); + struct commit_counters_hot *cc_hot; CHAN_WARN_ON(chan, config->alloc != RING_BUFFER_ALLOC_PER_CPU); CHAN_WARN_ON(chan, config->sync != RING_BUFFER_SYNC_PER_CPU); - if (caa_unlikely(!cc_hot)) - return 0; - /* * Read offset and commit count in a loop so they are both read * atomically wrt interrupts. By deal with interrupt concurrency by @@ -279,6 +268,9 @@ int lib_ring_buffer_reserve_committed(const struct lttng_ust_lib_ring_buffer_con do { offset = v_read(config, &buf->offset); idx = subbuf_index(offset, chan); + cc_hot = shmp_index(handle, buf->commit_hot, idx); + if (caa_unlikely(!cc_hot)) + return 0; commit_count = v_read(config, &cc_hot->cc); } while (offset != v_read(config, &buf->offset)); @@ -349,14 +341,17 @@ void lib_ring_buffer_write_commit_counter(const struct lttng_ust_lib_ring_buffer v_set(config, &cc_hot->seq, commit_count); } +LTTNG_HIDDEN extern int lib_ring_buffer_create(struct lttng_ust_lib_ring_buffer *buf, struct channel_backend *chanb, int cpu, struct lttng_ust_shm_handle *handle, struct shm_object *shmobj); +LTTNG_HIDDEN extern void lib_ring_buffer_free(struct lttng_ust_lib_ring_buffer *buf, struct lttng_ust_shm_handle *handle); /* Keep track of trap nesting inside ring buffer code */ +LTTNG_HIDDEN extern DECLARE_URCU_TLS(unsigned int, lib_ring_buffer_nesting); #endif /* _LTTNG_RING_BUFFER_FRONTEND_INTERNAL_H */