X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=libringbuffer%2Ffrontend_api.h;h=7cbad40fe543e540a23197a6b1895147a1fb4956;hb=50d2bb48d09d5b6ae23185e8f916152e2371d04a;hp=df9d56ff5e55b25510cea1323aa31ed2583881e3;hpb=38fae1d354502ffb37f471fbd0fef03412606cc0;p=lttng-ust.git diff --git a/libringbuffer/frontend_api.h b/libringbuffer/frontend_api.h index df9d56ff..7cbad40f 100644 --- a/libringbuffer/frontend_api.h +++ b/libringbuffer/frontend_api.h @@ -1,34 +1,28 @@ -#ifndef _LINUX_RING_BUFFER_FRONTEND_API_H -#define _LINUX_RING_BUFFER_FRONTEND_API_H - /* - * linux/ringbuffer/frontend_api.h - * - * (C) Copyright 2005-2010 - Mathieu Desnoyers - * - * Ring Buffer Library Synchronization Header (buffer write API). - * - * Author: - * Mathieu Desnoyers + * SPDX-License-Identifier: LGPL-2.1-only * - * See ring_buffer_frontend.c for more information on wait-free algorithms. - * See linux/ringbuffer/frontend.h for channel allocation and read-side API. + * Copyright (C) 2005-2012 Mathieu Desnoyers * - * Dual LGPL v2.1/GPL v2 license. + * 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 "ust/core.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 @@ -37,33 +31,25 @@ * section. */ static inline -int lib_ring_buffer_get_cpu(const struct 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 = ust_get_cpu(); - nesting = ++lib_ring_buffer_nesting; /* TLS */ + nesting = ++URCU_TLS(lib_ring_buffer_nesting); cmm_barrier(); - - if (unlikely(nesting > 4)) { + if (caa_unlikely(nesting > 4)) { WARN_ON_ONCE(1); - lib_ring_buffer_nesting--; /* TLS */ - rcu_read_unlock(); + URCU_TLS(lib_ring_buffer_nesting)--; 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 lib_ring_buffer_config *config) +void lib_ring_buffer_nesting_dec(const struct lttng_ust_lib_ring_buffer_config *config) { cmm_barrier(); - lib_ring_buffer_nesting--; /* TLS */ - rcu_read_unlock(); + URCU_TLS(lib_ring_buffer_nesting)--; /* TLS */ } /* @@ -73,13 +59,14 @@ void lib_ring_buffer_put_cpu(const struct lib_ring_buffer_config *config) * returns 0 if reserve ok, or 1 if the slow path must be taken. */ static inline -int lib_ring_buffer_try_reserve(const struct lib_ring_buffer_config *config, - struct lib_ring_buffer_ctx *ctx, +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 lib_ring_buffer *buf = ctx->buf; + 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; @@ -97,15 +84,15 @@ int lib_ring_buffer_try_reserve(const struct lib_ring_buffer_config *config, if (last_tsc_overflow(config, buf, ctx->tsc)) ctx->rflags |= RING_BUFFER_RFLAG_FULL_TSC; - if (unlikely(subbuf_offset(*o_begin, chan) == 0)) + if (caa_unlikely(subbuf_offset(*o_begin, chan) == 0)) 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; - if (unlikely((subbuf_offset(*o_begin, chan) + ctx->slot_size) + if (caa_unlikely((subbuf_offset(*o_begin, chan) + ctx->slot_size) > chan->backend.subbuf_size)) return 1; @@ -115,7 +102,7 @@ int lib_ring_buffer_try_reserve(const struct lib_ring_buffer_config *config, */ *o_end = *o_begin + ctx->slot_size; - if (unlikely((subbuf_offset(*o_end, chan)) == 0)) + if (caa_unlikely((subbuf_offset(*o_end, chan)) == 0)) /* * The offset_end will fall at the very beginning of the next * subbuffer. @@ -142,34 +129,39 @@ int lib_ring_buffer_try_reserve(const struct lib_ring_buffer_config *config, */ static inline -int lib_ring_buffer_reserve(const struct lib_ring_buffer_config *config, - struct lib_ring_buffer_ctx *ctx) +int lib_ring_buffer_reserve(const struct lttng_ust_lib_ring_buffer_config *config, + struct lttng_ust_lib_ring_buffer_ctx *ctx, + void *client_ctx) { - struct channel *chan = ctx->chan; - struct lttng_ust_shm_handle *handle = ctx->handle; - struct lib_ring_buffer *buf; + struct lttng_ust_lib_ring_buffer_channel *chan = ctx->chan; + struct lttng_ust_shm_handle *handle = ctx->chan->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 (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; - if (unlikely(v_cmpxchg(config, &ctx->buf->offset, o_old, o_end) + if (caa_unlikely(v_cmpxchg(config, &ctx->buf->offset, o_old, o_end) != o_old)) goto slow_path; @@ -196,7 +188,7 @@ int lib_ring_buffer_reserve(const struct lib_ring_buffer_config *config, 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); } /** @@ -214,8 +206,8 @@ slow_path: * disabled, for RING_BUFFER_SYNC_PER_CPU configuration. */ static inline -void lib_ring_buffer_switch(const struct lib_ring_buffer_config *config, - struct lib_ring_buffer *buf, enum switch_mode mode, +void lib_ring_buffer_switch(const struct lttng_ust_lib_ring_buffer_config *config, + struct lttng_ust_lib_ring_buffer *buf, enum switch_mode mode, struct lttng_ust_shm_handle *handle) { lib_ring_buffer_switch_slow(buf, mode, handle); @@ -232,20 +224,25 @@ void lib_ring_buffer_switch(const struct lib_ring_buffer_config *config, * specified sub-buffer, and delivers it if necessary. */ static inline -void lib_ring_buffer_commit(const struct lib_ring_buffer_config *config, - const struct lib_ring_buffer_ctx *ctx) +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_shm_handle *handle = ctx->handle; - struct lib_ring_buffer *buf = ctx->buf; + struct lttng_ust_lib_ring_buffer_channel *chan = ctx->chan; + struct lttng_ust_shm_handle *handle = ctx->chan->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 @@ -253,7 +250,7 @@ void lib_ring_buffer_commit(const struct lib_ring_buffer_config *config, */ 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. @@ -273,17 +270,16 @@ void lib_ring_buffer_commit(const struct lib_ring_buffer_config *config, * 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); } /** @@ -297,10 +293,10 @@ void lib_ring_buffer_commit(const struct lib_ring_buffer_config *config, * Returns 0 upon success, -EPERM if the record cannot be discarded. */ static inline -int lib_ring_buffer_try_discard_reserve(const struct lib_ring_buffer_config *config, - const struct lib_ring_buffer_ctx *ctx) +int lib_ring_buffer_try_discard_reserve(const struct lttng_ust_lib_ring_buffer_config *config, + const struct lttng_ust_lib_ring_buffer_ctx *ctx) { - struct lib_ring_buffer *buf = ctx->buf; + struct lttng_ust_lib_ring_buffer *buf = ctx->buf; unsigned long end_offset = ctx->pre_offset + ctx->slot_size; /* @@ -317,7 +313,7 @@ int lib_ring_buffer_try_discard_reserve(const struct lib_ring_buffer_config *con */ save_last_tsc(config, buf, 0ULL); - if (likely(v_cmpxchg(config, &buf->offset, end_offset, ctx->pre_offset) + if (caa_likely(v_cmpxchg(config, &buf->offset, end_offset, ctx->pre_offset) != end_offset)) return -EPERM; else @@ -325,31 +321,31 @@ int lib_ring_buffer_try_discard_reserve(const struct lib_ring_buffer_config *con } static inline -void channel_record_disable(const struct lib_ring_buffer_config *config, - struct channel *chan) +void channel_record_disable(const struct lttng_ust_lib_ring_buffer_config *config, + struct lttng_ust_lib_ring_buffer_channel *chan) { uatomic_inc(&chan->record_disabled); } static inline -void channel_record_enable(const struct lib_ring_buffer_config *config, - struct channel *chan) +void channel_record_enable(const struct lttng_ust_lib_ring_buffer_config *config, + struct lttng_ust_lib_ring_buffer_channel *chan) { uatomic_dec(&chan->record_disabled); } static inline -void lib_ring_buffer_record_disable(const struct lib_ring_buffer_config *config, - struct lib_ring_buffer *buf) +void lib_ring_buffer_record_disable(const struct lttng_ust_lib_ring_buffer_config *config, + struct lttng_ust_lib_ring_buffer *buf) { uatomic_inc(&buf->record_disabled); } static inline -void lib_ring_buffer_record_enable(const struct lib_ring_buffer_config *config, - struct lib_ring_buffer *buf) +void lib_ring_buffer_record_enable(const struct lttng_ust_lib_ring_buffer_config *config, + struct lttng_ust_lib_ring_buffer *buf) { uatomic_dec(&buf->record_disabled); } -#endif /* _LINUX_RING_BUFFER_FRONTEND_API_H */ +#endif /* _LTTNG_RING_BUFFER_FRONTEND_API_H */