X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=libringbuffer%2Ffrontend_internal.h;h=4ad921ec0ec8263086cddbf1c11044110dc672f6;hb=HEAD;hp=6e9d8be2f1c988362de1e21200a8968d462f7005;hpb=0466ac28c41336fd6d373cc8b0b26ef132225b9f;p=lttng-ust.git diff --git a/libringbuffer/frontend_internal.h b/libringbuffer/frontend_internal.h deleted file mode 100644 index 6e9d8be2..00000000 --- a/libringbuffer/frontend_internal.h +++ /dev/null @@ -1,365 +0,0 @@ -/* - * SPDX-License-Identifier: (LGPL-2.1-only or GPL-2.0-only) - * - * Copyright (C) 2005-2012 Mathieu Desnoyers - * - * Ring Buffer Library Synchronization Header (internal helpers). - * - * See ring_buffer_frontend.c for more information on wait-free algorithms. - */ - -#ifndef _LTTNG_RING_BUFFER_FRONTEND_INTERNAL_H -#define _LTTNG_RING_BUFFER_FRONTEND_INTERNAL_H - -#include -#include -#include -#include -#include - -#include -#include "ringbuffer-config.h" -#include "backend_types.h" -#include "frontend_types.h" -#include "shm.h" - -/* Buffer offset macros */ - -/* buf_trunc mask selects only the buffer number. */ -static inline -unsigned long buf_trunc(unsigned long offset, - struct lttng_ust_lib_ring_buffer_channel *chan) -{ - return offset & ~(chan->backend.buf_size - 1); - -} - -/* Select the buffer number value (counter). */ -static inline -unsigned long buf_trunc_val(unsigned long offset, - struct lttng_ust_lib_ring_buffer_channel *chan) -{ - return buf_trunc(offset, chan) >> chan->backend.buf_size_order; -} - -/* buf_offset mask selects only the offset within the current buffer. */ -static inline -unsigned long buf_offset(unsigned long offset, - struct lttng_ust_lib_ring_buffer_channel *chan) -{ - return offset & (chan->backend.buf_size - 1); -} - -/* subbuf_offset mask selects the offset within the current subbuffer. */ -static inline -unsigned long subbuf_offset(unsigned long offset, - struct lttng_ust_lib_ring_buffer_channel *chan) -{ - return offset & (chan->backend.subbuf_size - 1); -} - -/* subbuf_trunc mask selects the subbuffer number. */ -static inline -unsigned long subbuf_trunc(unsigned long offset, - struct lttng_ust_lib_ring_buffer_channel *chan) -{ - return offset & ~(chan->backend.subbuf_size - 1); -} - -/* subbuf_align aligns the offset to the next subbuffer. */ -static inline -unsigned long subbuf_align(unsigned long offset, - struct lttng_ust_lib_ring_buffer_channel *chan) -{ - return (offset + chan->backend.subbuf_size) - & ~(chan->backend.subbuf_size - 1); -} - -/* subbuf_index returns the index of the current subbuffer within the buffer. */ -static inline -unsigned long subbuf_index(unsigned long offset, - struct lttng_ust_lib_ring_buffer_channel *chan) -{ - return buf_offset(offset, chan) >> chan->backend.subbuf_size_order; -} - -/* - * Last TSC comparison functions. Check if the current TSC overflows tsc_bits - * bits from the last TSC read. When overflows are detected, the full 64-bit - * timestamp counter should be written in the record header. Reads and writes - * last_tsc atomically. - */ - -#if (CAA_BITS_PER_LONG == 32) -static inline -void save_last_tsc(const struct lttng_ust_lib_ring_buffer_config *config, - struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc) -{ - if (config->tsc_bits == 0 || config->tsc_bits == 64) - return; - - /* - * Ensure the compiler performs this update in a single instruction. - */ - v_set(config, &buf->last_tsc, (unsigned long)(tsc >> config->tsc_bits)); -} - -static inline -int last_tsc_overflow(const struct lttng_ust_lib_ring_buffer_config *config, - struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc) -{ - unsigned long tsc_shifted; - - if (config->tsc_bits == 0 || config->tsc_bits == 64) - return 0; - - tsc_shifted = (unsigned long)(tsc >> config->tsc_bits); - if (caa_unlikely(tsc_shifted - - (unsigned long)v_read(config, &buf->last_tsc))) - return 1; - else - return 0; -} -#else -static inline -void save_last_tsc(const struct lttng_ust_lib_ring_buffer_config *config, - struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc) -{ - if (config->tsc_bits == 0 || config->tsc_bits == 64) - return; - - v_set(config, &buf->last_tsc, (unsigned long)tsc); -} - -static inline -int last_tsc_overflow(const struct lttng_ust_lib_ring_buffer_config *config, - struct lttng_ust_lib_ring_buffer *buf, uint64_t tsc) -{ - if (config->tsc_bits == 0 || config->tsc_bits == 64) - return 0; - - if (caa_unlikely((tsc - v_read(config, &buf->last_tsc)) - >> config->tsc_bits)) - return 1; - else - return 0; -} -#endif - -__attribute__((visibility("hidden"))) -extern -int lib_ring_buffer_reserve_slow(struct lttng_ust_lib_ring_buffer_ctx *ctx, - void *client_ctx); - -__attribute__((visibility("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); - -__attribute__((visibility("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 lttng_ust_lib_ring_buffer_channel *chan, - unsigned long offset, - unsigned long commit_count, - unsigned long idx, - struct lttng_ust_shm_handle *handle, - uint64_t tsc); - -/* Buffer write helpers */ - -static inline -void lib_ring_buffer_reserve_push_reader(struct lttng_ust_lib_ring_buffer *buf, - struct lttng_ust_lib_ring_buffer_channel *chan, - unsigned long offset) -{ - unsigned long consumed_old, consumed_new; - - do { - consumed_old = uatomic_read(&buf->consumed); - /* - * If buffer is in overwrite mode, push the reader consumed - * count if the write position has reached it and we are not - * at the first iteration (don't push the reader farther than - * the writer). This operation can be done concurrently by many - * writers in the same buffer, the writer being at the farthest - * write position sub-buffer index in the buffer being the one - * which will win this loop. - */ - if (caa_unlikely(subbuf_trunc(offset, chan) - - subbuf_trunc(consumed_old, chan) - >= chan->backend.buf_size)) - consumed_new = subbuf_align(consumed_old, chan); - else - return; - } while (caa_unlikely(uatomic_cmpxchg(&buf->consumed, consumed_old, - 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) -{ - struct lttng_ust_lib_ring_buffer_channel *chan; - const struct lttng_ust_lib_ring_buffer_config *config; - unsigned long offset, consumed_old, consumed_new; - - chan = shmp(handle, buf->backend.chan); - if (!chan) - return; - config = &chan->backend.config; - - do { - offset = v_read(config, &buf->offset); - consumed_old = uatomic_read(&buf->consumed); - 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)); -} - -static inline -int lib_ring_buffer_pending_data(const struct lttng_ust_lib_ring_buffer_config *config, - struct lttng_ust_lib_ring_buffer *buf, - struct lttng_ust_lib_ring_buffer_channel *chan) -{ - return !!subbuf_offset(v_read(config, &buf->offset), chan); -} - -static inline -unsigned long lib_ring_buffer_get_data_size(const struct lttng_ust_lib_ring_buffer_config *config, - struct lttng_ust_lib_ring_buffer *buf, - unsigned long idx, - struct lttng_ust_shm_handle *handle) -{ - return subbuffer_get_data_size(config, &buf->backend, idx, handle); -} - -/* - * Check if all space reservation in a buffer have been committed. This helps - * knowing if an execution context is nested (for per-cpu buffers only). - * This is a very specific ftrace use-case, so we keep this as "internal" API. - */ -static inline -int lib_ring_buffer_reserve_committed(const struct lttng_ust_lib_ring_buffer_config *config, - struct lttng_ust_lib_ring_buffer *buf, - struct lttng_ust_lib_ring_buffer_channel *chan, - struct lttng_ust_shm_handle *handle) -{ - unsigned long offset, idx, commit_count; - 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); - - /* - * Read offset and commit count in a loop so they are both read - * atomically wrt interrupts. By deal with interrupt concurrency by - * restarting both reads if the offset has been pushed. Note that given - * we only have to deal with interrupt concurrency here, an interrupt - * modifying the commit count will also modify "offset", so it is safe - * to only check for offset modifications. - */ - 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)); - - return ((buf_trunc(offset, chan) >> chan->backend.num_subbuf_order) - - (commit_count & chan->commit_count_mask) == 0); -} - -/* - * Receive end of subbuffer TSC as parameter. It has been read in the - * space reservation loop of either reserve or switch, which ensures it - * progresses monotonically with event records in the buffer. Therefore, - * it ensures that the end timestamp of a subbuffer is <= begin - * timestamp of the following subbuffers. - */ -static inline -void lib_ring_buffer_check_deliver(const struct lttng_ust_lib_ring_buffer_config *config, - struct lttng_ust_lib_ring_buffer *buf, - struct lttng_ust_lib_ring_buffer_channel *chan, - unsigned long offset, - unsigned long commit_count, - unsigned long idx, - struct lttng_ust_shm_handle *handle, - uint64_t tsc) -{ - unsigned long old_commit_count = commit_count - - chan->backend.subbuf_size; - - /* Check if all commits have been done */ - if (caa_unlikely((buf_trunc(offset, chan) >> chan->backend.num_subbuf_order) - - (old_commit_count & chan->commit_count_mask) == 0)) - lib_ring_buffer_check_deliver_slow(config, buf, chan, offset, - commit_count, idx, handle, tsc); -} - -/* - * lib_ring_buffer_write_commit_counter - * - * For flight recording. must be called after commit. - * This function increments the subbuffer's commit_seq counter each time the - * commit count reaches back the reserve offset (modulo subbuffer size). It is - * useful for crash dump. - */ -static inline -void lib_ring_buffer_write_commit_counter(const struct lttng_ust_lib_ring_buffer_config *config, - struct lttng_ust_lib_ring_buffer *buf, - struct lttng_ust_lib_ring_buffer_channel *chan, - unsigned long buf_offset, - unsigned long commit_count, - struct lttng_ust_shm_handle *handle, - struct commit_counters_hot *cc_hot) -{ - unsigned long commit_seq_old; - - if (config->oops != RING_BUFFER_OOPS_CONSISTENCY) - return; - - /* - * subbuf_offset includes commit_count_mask. We can simply - * compare the offsets within the subbuffer without caring about - * buffer full/empty mismatch because offset is never zero here - * (subbuffer header and record headers have non-zero length). - */ - if (caa_unlikely(subbuf_offset(buf_offset - commit_count, chan))) - return; - - commit_seq_old = v_read(config, &cc_hot->seq); - if (caa_likely((long) (commit_seq_old - commit_count) < 0)) - v_set(config, &cc_hot->seq, commit_count); -} - -__attribute__((visibility("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); - -__attribute__((visibility("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 */ -__attribute__((visibility("hidden"))) -extern DECLARE_URCU_TLS(unsigned int, lib_ring_buffer_nesting); - -#endif /* _LTTNG_RING_BUFFER_FRONTEND_INTERNAL_H */