X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=libringbuffer%2Ffrontend_api.h;h=8a32006139afed25204c1594408ecaae54b3f46d;hb=b4051ad8c170901d5297e1b3005b24e63cb0ab1e;hp=ebe5db493f71f220d1d05f9117a9f53bbcf036b6;hpb=b9b858b8e2527bc30a7ed8a09b0962eb93e5c940;p=lttng-ust.git diff --git a/libringbuffer/frontend_api.h b/libringbuffer/frontend_api.h index ebe5db49..8a320061 100644 --- a/libringbuffer/frontend_api.h +++ b/libringbuffer/frontend_api.h @@ -1,31 +1,49 @@ -#ifndef _LINUX_RING_BUFFER_FRONTEND_API_H -#define _LINUX_RING_BUFFER_FRONTEND_API_H +#ifndef _LTTNG_RING_BUFFER_FRONTEND_API_H +#define _LTTNG_RING_BUFFER_FRONTEND_API_H /* - * linux/ringbuffer/frontend_api.h + * libringbuffer/frontend_api.h * - * (C) Copyright 2005-2010 - Mathieu Desnoyers + * 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 + * Mathieu Desnoyers * - * See ring_buffer_frontend.c for more information on wait-free algorithms. - * See linux/ringbuffer/frontend.h for channel allocation and read-side API. - * - * 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 + +#include +#include + #include "frontend.h" /** * lib_ring_buffer_get_cpu - Precedes ring buffer reserve/commit. * - * Disables preemption (acts as a RCU read-side critical section) 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). + * 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). * * asm volatile and "memory" clobber prevent the compiler from moving * instructions out of the ring buffer nesting count. This is required to ensure @@ -34,19 +52,17 @@ * section. */ static inline -int lib_ring_buffer_get_cpu(const struct lib_ring_buffer_config *config) +int lib_ring_buffer_get_cpu(const struct lttng_ust_lib_ring_buffer_config *config) { int cpu, nesting; - rcu_read_lock_sched_notrace(); - cpu = smp_processor_id(); - nesting = ++lib_ring_buffer_nesting; /* TLS */ - barrier(); + cpu = lttng_ust_get_cpu(); + 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_sched_notrace(); + URCU_TLS(lib_ring_buffer_nesting)--; return -EPERM; } else return cpu; @@ -56,11 +72,10 @@ int lib_ring_buffer_get_cpu(const struct lib_ring_buffer_config *config) * 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_put_cpu(const struct lttng_ust_lib_ring_buffer_config *config) { - barrier(); - lib_ring_buffer_nesting--; /* TLS */ - rcu_read_unlock_sched_notrace(); + cmm_barrier(); + URCU_TLS(lib_ring_buffer_nesting)--; /* TLS */ } /* @@ -70,13 +85,14 @@ 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 *buf = ctx->buf; *o_begin = v_read(config, &buf->offset); *o_old = *o_begin; @@ -89,20 +105,20 @@ int lib_ring_buffer_try_reserve(const struct lib_ring_buffer_config *config, * commit counter to increment it and commit seq value to compare it to * the commit counter. */ - prefetch(&buf->commit_hot[subbuf_index(*o_begin, chan)]); + //prefetch(&buf->commit_hot[subbuf_index(*o_begin, chan)]); 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; @@ -112,7 +128,7 @@ 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. @@ -139,33 +155,37 @@ 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 lib_ring_buffer *buf; + 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 (atomic_read(&chan->record_disabled)) + if (caa_unlikely(uatomic_read(&chan->record_disabled))) return -EAGAIN; if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) - buf = per_cpu_ptr(chan->backend.buf, ctx->cpu); + buf = shmp(handle, chan->backend.buf[ctx->cpu].shmp); else - buf = chan->backend.buf; - if (atomic_read(&buf->record_disabled)) + buf = shmp(handle, chan->backend.buf[0].shmp); + 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; @@ -186,13 +206,13 @@ int lib_ring_buffer_reserve(const struct lib_ring_buffer_config *config, * Clear noref flag for this subbuffer. */ lib_ring_buffer_clear_noref(config, &ctx->buf->backend, - subbuf_index(o_end - 1, chan)); + subbuf_index(o_end - 1, chan), handle); ctx->pre_offset = o_begin; 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); } /** @@ -210,10 +230,11 @@ 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); + lib_ring_buffer_switch_slow(buf, mode, handle); } /* See ring_buffer_frontend_api.h for lib_ring_buffer_reserve(). */ @@ -227,35 +248,33 @@ 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 lib_ring_buffer *buf = ctx->buf; + 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); + subbuffer_count_record(config, ctx, &buf->backend, endidx, handle); /* * Order all writes to buffer before the commit count update that will * determine that the subbuffer is full. */ - if (config->ipi == RING_BUFFER_IPI_BARRIER) { - /* - * Must write slot data before incrementing commit count. This - * compiler barrier is upgraded into a smp_mb() by the IPI sent - * by get_subbuf(). - */ - barrier(); - } else - smp_wmb(); + cmm_smp_wmb(); - v_add(config, ctx->slot_size, &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. @@ -275,17 +294,16 @@ 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, &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); + 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); + lib_ring_buffer_write_commit_counter(config, buf, chan, + offset_end, commit_count, handle, cc_hot); } /** @@ -299,10 +317,10 @@ 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; /* @@ -319,7 +337,7 @@ 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 @@ -327,31 +345,31 @@ 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, +void channel_record_disable(const struct lttng_ust_lib_ring_buffer_config *config, struct channel *chan) { - atomic_inc(&chan->record_disabled); + uatomic_inc(&chan->record_disabled); } static inline -void channel_record_enable(const struct lib_ring_buffer_config *config, +void channel_record_enable(const struct lttng_ust_lib_ring_buffer_config *config, struct channel *chan) { - atomic_dec(&chan->record_disabled); + 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) { - atomic_inc(&buf->record_disabled); + 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) { - atomic_dec(&buf->record_disabled); + uatomic_dec(&buf->record_disabled); } -#endif /* _LINUX_RING_BUFFER_FRONTEND_API_H */ +#endif /* _LTTNG_RING_BUFFER_FRONTEND_API_H */