X-Git-Url: http://git.lttng.org./?a=blobdiff_plain;f=libringbuffer%2Ffrontend_api.h;h=96f79554b3764bb3cb40d140e34b5ebcebcc725e;hb=7489fcb466935b3eeb36e99afbbb87188278cb91;hp=b5406b0ef9d3678d44f706b23d66117b5659fd9e;hpb=019fbcb65ec7eec2c86019ad1afce8fa47dc1269;p=lttng-ust.git diff --git a/libringbuffer/frontend_api.h b/libringbuffer/frontend_api.h index b5406b0e..96f79554 100644 --- a/libringbuffer/frontend_api.h +++ b/libringbuffer/frontend_api.h @@ -1,46 +1,28 @@ -#ifndef _LTTNG_RING_BUFFER_FRONTEND_API_H -#define _LTTNG_RING_BUFFER_FRONTEND_API_H - /* - * libringbuffer/frontend_api.h + * SPDX-License-Identifier: LGPL-2.1-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 - * - * Ring Buffer Library Synchronization Header (buffer write API). - * - * Author: - * Mathieu Desnoyers - * * See ring_buffer_frontend.c for more information on wait-free * algorithms. * See frontend.h for channel allocation and read-side API. */ -#include "frontend.h" -#include +#ifndef _LTTNG_RING_BUFFER_FRONTEND_API_H +#define _LTTNG_RING_BUFFER_FRONTEND_API_H + +#include + #include +#include "frontend.h" + /** - * lib_ring_buffer_get_cpu - Precedes ring buffer reserve/commit. + * lib_ring_buffer_nesting_inc - Ring buffer recursive use protection. * - * Grabs RCU read-side lock and keeps a ring buffer nesting count as - * supplementary safety net to ensure tracer client code will never - * trigger an endless recursion. Returns the processor ID on success, - * -EPERM on failure (nesting count too high). + * The rint buffer buffer nesting count is a safety net to ensure tracer + * client code will never trigger an endless recursion. + * Returns 0 on success, -EPERM on failure (nesting count too high). * * asm volatile and "memory" clobber prevent the compiler from moving * instructions out of the ring buffer nesting count. This is required to ensure @@ -49,33 +31,25 @@ * section. */ static inline -int lib_ring_buffer_get_cpu(const struct lttng_ust_lib_ring_buffer_config *config) +int lib_ring_buffer_nesting_inc(const struct lttng_ust_lib_ring_buffer_config *config) { - int cpu, nesting; + int nesting; - rcu_read_lock(); - cpu = lttng_ust_get_cpu(); nesting = ++URCU_TLS(lib_ring_buffer_nesting); cmm_barrier(); - if (caa_unlikely(nesting > 4)) { WARN_ON_ONCE(1); URCU_TLS(lib_ring_buffer_nesting)--; - rcu_read_unlock(); return -EPERM; - } else - return cpu; + } + return 0; } -/** - * lib_ring_buffer_put_cpu - Follows ring buffer reserve/commit. - */ static inline -void lib_ring_buffer_put_cpu(const struct lttng_ust_lib_ring_buffer_config *config) +void lib_ring_buffer_nesting_dec(const struct lttng_ust_lib_ring_buffer_config *config) { cmm_barrier(); URCU_TLS(lib_ring_buffer_nesting)--; /* TLS */ - rcu_read_unlock(); } /* @@ -87,10 +61,11 @@ void lib_ring_buffer_put_cpu(const struct lttng_ust_lib_ring_buffer_config *conf static inline int lib_ring_buffer_try_reserve(const struct lttng_ust_lib_ring_buffer_config *config, struct lttng_ust_lib_ring_buffer_ctx *ctx, + void *client_ctx, unsigned long *o_begin, unsigned long *o_end, unsigned long *o_old, size_t *before_hdr_pad) { - struct channel *chan = ctx->chan; + struct lttng_ust_lib_ring_buffer_channel *chan = ctx->chan; struct lttng_ust_lib_ring_buffer *buf = ctx->buf; *o_begin = v_read(config, &buf->offset); *o_old = *o_begin; @@ -113,7 +88,7 @@ int lib_ring_buffer_try_reserve(const struct lttng_ust_lib_ring_buffer_config *c return 1; ctx->slot_size = record_header_size(config, chan, *o_begin, - before_hdr_pad, ctx); + before_hdr_pad, ctx, client_ctx); ctx->slot_size += lib_ring_buffer_align(*o_begin + ctx->slot_size, ctx->largest_align) + ctx->data_size; @@ -126,6 +101,14 @@ int lib_ring_buffer_try_reserve(const struct lttng_ust_lib_ring_buffer_config *c * boundary. It's safe to write. */ *o_end = *o_begin + ctx->slot_size; + + if (caa_unlikely((subbuf_offset(*o_end, chan)) == 0)) + /* + * The offset_end will fall at the very beginning of the next + * subbuffer. + */ + return 1; + return 0; } @@ -147,29 +130,34 @@ int lib_ring_buffer_try_reserve(const struct lttng_ust_lib_ring_buffer_config *c static inline int lib_ring_buffer_reserve(const struct lttng_ust_lib_ring_buffer_config *config, - struct lttng_ust_lib_ring_buffer_ctx *ctx) + struct lttng_ust_lib_ring_buffer_ctx *ctx, + void *client_ctx) { - struct channel *chan = ctx->chan; + struct lttng_ust_lib_ring_buffer_channel *chan = ctx->chan; struct lttng_ust_shm_handle *handle = ctx->handle; struct lttng_ust_lib_ring_buffer *buf; unsigned long o_begin, o_end, o_old; size_t before_hdr_pad = 0; - if (uatomic_read(&chan->record_disabled)) + if (caa_unlikely(uatomic_read(&chan->record_disabled))) return -EAGAIN; - if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) - buf = shmp(handle, chan->backend.buf[ctx->cpu].shmp); - else + if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) { + ctx->reserve_cpu = lttng_ust_get_cpu(); + buf = shmp(handle, chan->backend.buf[ctx->reserve_cpu].shmp); + } else { buf = shmp(handle, chan->backend.buf[0].shmp); - if (uatomic_read(&buf->record_disabled)) + } + if (caa_unlikely(!buf)) + return -EIO; + if (caa_unlikely(uatomic_read(&buf->record_disabled))) return -EAGAIN; ctx->buf = buf; /* * Perform retryable operations. */ - if (caa_unlikely(lib_ring_buffer_try_reserve(config, ctx, &o_begin, + if (caa_unlikely(lib_ring_buffer_try_reserve(config, ctx, client_ctx, &o_begin, &o_end, &o_old, &before_hdr_pad))) goto slow_path; @@ -200,7 +188,7 @@ int lib_ring_buffer_reserve(const struct lttng_ust_lib_ring_buffer_config *confi ctx->buf_offset = o_begin + before_hdr_pad; return 0; slow_path: - return lib_ring_buffer_reserve_slow(ctx); + return lib_ring_buffer_reserve_slow(ctx, client_ctx); } /** @@ -239,17 +227,22 @@ static inline void lib_ring_buffer_commit(const struct lttng_ust_lib_ring_buffer_config *config, const struct lttng_ust_lib_ring_buffer_ctx *ctx) { - struct channel *chan = ctx->chan; + struct lttng_ust_lib_ring_buffer_channel *chan = ctx->chan; struct lttng_ust_shm_handle *handle = ctx->handle; struct lttng_ust_lib_ring_buffer *buf = ctx->buf; unsigned long offset_end = ctx->buf_offset; unsigned long endidx = subbuf_index(offset_end - 1, chan); unsigned long commit_count; + struct commit_counters_hot *cc_hot = shmp_index(handle, + buf->commit_hot, endidx); + + if (caa_unlikely(!cc_hot)) + return; /* * Must count record before incrementing the commit count. */ - subbuffer_count_record(config, &buf->backend, endidx, handle); + subbuffer_count_record(config, ctx, &buf->backend, endidx, handle); /* * Order all writes to buffer before the commit count update that will @@ -257,7 +250,7 @@ void lib_ring_buffer_commit(const struct lttng_ust_lib_ring_buffer_config *confi */ cmm_smp_wmb(); - v_add(config, ctx->slot_size, &shmp_index(handle, buf->commit_hot, endidx)->cc); + v_add(config, ctx->slot_size, &cc_hot->cc); /* * commit count read can race with concurrent OOO commit count updates. @@ -277,17 +270,16 @@ void lib_ring_buffer_commit(const struct lttng_ust_lib_ring_buffer_config *confi * count reaches back the reserve offset for a specific sub-buffer, * which is completely independent of the order. */ - commit_count = v_read(config, &shmp_index(handle, buf->commit_hot, endidx)->cc); + commit_count = v_read(config, &cc_hot->cc); lib_ring_buffer_check_deliver(config, buf, chan, offset_end - 1, - commit_count, endidx, handle); + commit_count, endidx, handle, ctx->tsc); /* * Update used size at each commit. It's needed only for extracting * ring_buffer buffers from vmcore, after crash. */ - lib_ring_buffer_write_commit_counter(config, buf, chan, endidx, - ctx->buf_offset, commit_count, - ctx->slot_size, handle); + lib_ring_buffer_write_commit_counter(config, buf, chan, + offset_end, commit_count, handle, cc_hot); } /** @@ -330,14 +322,14 @@ int lib_ring_buffer_try_discard_reserve(const struct lttng_ust_lib_ring_buffer_c static inline void channel_record_disable(const struct lttng_ust_lib_ring_buffer_config *config, - struct channel *chan) + struct lttng_ust_lib_ring_buffer_channel *chan) { uatomic_inc(&chan->record_disabled); } static inline void channel_record_enable(const struct lttng_ust_lib_ring_buffer_config *config, - struct channel *chan) + struct lttng_ust_lib_ring_buffer_channel *chan) { uatomic_dec(&chan->record_disabled); }