ust-fd: Add close_range declaration
[lttng-ust.git] / libringbuffer / backend_internal.h
diff --git a/libringbuffer/backend_internal.h b/libringbuffer/backend_internal.h
deleted file mode 100644 (file)
index fe8f6eb..0000000
+++ /dev/null
@@ -1,686 +0,0 @@
-#ifndef _LTTNG_RING_BUFFER_BACKEND_INTERNAL_H
-#define _LTTNG_RING_BUFFER_BACKEND_INTERNAL_H
-
-/*
- * libringbuffer/backend_internal.h
- *
- * Ring buffer backend (internal helpers).
- *
- * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
- * 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
- */
-
-#include <stddef.h>
-#include <stdint.h>
-#include <unistd.h>
-#include <urcu/compiler.h>
-
-#include <lttng/ringbuffer-config.h>
-#include "backend_types.h"
-#include "frontend_types.h"
-#include "shm.h"
-
-/* Ring buffer backend API presented to the frontend */
-
-/* Ring buffer and channel backend create/free */
-
-int lib_ring_buffer_backend_create(struct lttng_ust_lib_ring_buffer_backend *bufb,
-                                  struct channel_backend *chan, int cpu,
-                                  struct lttng_ust_shm_handle *handle,
-                                  struct shm_object *shmobj);
-void channel_backend_unregister_notifiers(struct channel_backend *chanb);
-void lib_ring_buffer_backend_free(struct lttng_ust_lib_ring_buffer_backend *bufb);
-int channel_backend_init(struct channel_backend *chanb,
-                        const char *name,
-                        const struct lttng_ust_lib_ring_buffer_config *config,
-                        size_t subbuf_size,
-                        size_t num_subbuf, struct lttng_ust_shm_handle *handle,
-                        const int *stream_fds);
-void channel_backend_free(struct channel_backend *chanb,
-                         struct lttng_ust_shm_handle *handle);
-
-void lib_ring_buffer_backend_reset(struct lttng_ust_lib_ring_buffer_backend *bufb,
-                                  struct lttng_ust_shm_handle *handle);
-void channel_backend_reset(struct channel_backend *chanb);
-
-int lib_ring_buffer_backend_init(void);
-void lib_ring_buffer_backend_exit(void);
-
-extern void _lib_ring_buffer_write(struct lttng_ust_lib_ring_buffer_backend *bufb,
-                                  size_t offset, const void *src, size_t len,
-                                  ssize_t pagecpy);
-
-/*
- * Subbuffer ID bits for overwrite mode. Need to fit within a single word to be
- * exchanged atomically.
- *
- * Top half word, except lowest bit, belongs to "offset", which is used to keep
- * to count the produced buffers.  For overwrite mode, this provides the
- * consumer with the capacity to read subbuffers in order, handling the
- * situation where producers would write up to 2^15 buffers (or 2^31 for 64-bit
- * systems) concurrently with a single execution of get_subbuf (between offset
- * sampling and subbuffer ID exchange).
- */
-
-#define HALF_ULONG_BITS                (CAA_BITS_PER_LONG >> 1)
-
-#define SB_ID_OFFSET_SHIFT     (HALF_ULONG_BITS + 1)
-#define SB_ID_OFFSET_COUNT     (1UL << SB_ID_OFFSET_SHIFT)
-#define SB_ID_OFFSET_MASK      (~(SB_ID_OFFSET_COUNT - 1))
-/*
- * Lowest bit of top word half belongs to noref. Used only for overwrite mode.
- */
-#define SB_ID_NOREF_SHIFT      (SB_ID_OFFSET_SHIFT - 1)
-#define SB_ID_NOREF_COUNT      (1UL << SB_ID_NOREF_SHIFT)
-#define SB_ID_NOREF_MASK       SB_ID_NOREF_COUNT
-/*
- * In overwrite mode: lowest half of word is used for index.
- * Limit of 2^16 subbuffers per buffer on 32-bit, 2^32 on 64-bit.
- * In producer-consumer mode: whole word used for index.
- */
-#define SB_ID_INDEX_SHIFT      0
-#define SB_ID_INDEX_COUNT      (1UL << SB_ID_INDEX_SHIFT)
-#define SB_ID_INDEX_MASK       (SB_ID_NOREF_COUNT - 1)
-
-/*
- * Construct the subbuffer id from offset, index and noref. Use only the index
- * for producer-consumer mode (offset and noref are only used in overwrite
- * mode).
- */
-static inline
-unsigned long subbuffer_id(const struct lttng_ust_lib_ring_buffer_config *config,
-                          unsigned long offset, unsigned long noref,
-                          unsigned long index)
-{
-       if (config->mode == RING_BUFFER_OVERWRITE)
-               return (offset << SB_ID_OFFSET_SHIFT)
-                      | (noref << SB_ID_NOREF_SHIFT)
-                      | index;
-       else
-               return index;
-}
-
-/*
- * Compare offset with the offset contained within id. Return 1 if the offset
- * bits are identical, else 0.
- */
-static inline
-int subbuffer_id_compare_offset(const struct lttng_ust_lib_ring_buffer_config *config,
-                               unsigned long id, unsigned long offset)
-{
-       return (id & SB_ID_OFFSET_MASK) == (offset << SB_ID_OFFSET_SHIFT);
-}
-
-static inline
-unsigned long subbuffer_id_get_index(const struct lttng_ust_lib_ring_buffer_config *config,
-                                    unsigned long id)
-{
-       if (config->mode == RING_BUFFER_OVERWRITE)
-               return id & SB_ID_INDEX_MASK;
-       else
-               return id;
-}
-
-static inline
-unsigned long subbuffer_id_is_noref(const struct lttng_ust_lib_ring_buffer_config *config,
-                                   unsigned long id)
-{
-       if (config->mode == RING_BUFFER_OVERWRITE)
-               return !!(id & SB_ID_NOREF_MASK);
-       else
-               return 1;
-}
-
-/*
- * Only used by reader on subbuffer ID it has exclusive access to. No volatile
- * needed.
- */
-static inline
-void subbuffer_id_set_noref(const struct lttng_ust_lib_ring_buffer_config *config,
-                           unsigned long *id)
-{
-       if (config->mode == RING_BUFFER_OVERWRITE)
-               *id |= SB_ID_NOREF_MASK;
-}
-
-static inline
-void subbuffer_id_set_noref_offset(const struct lttng_ust_lib_ring_buffer_config *config,
-                                  unsigned long *id, unsigned long offset)
-{
-       unsigned long tmp;
-
-       if (config->mode == RING_BUFFER_OVERWRITE) {
-               tmp = *id;
-               tmp &= ~SB_ID_OFFSET_MASK;
-               tmp |= offset << SB_ID_OFFSET_SHIFT;
-               tmp |= SB_ID_NOREF_MASK;
-               /* Volatile store, read concurrently by readers. */
-               CMM_ACCESS_ONCE(*id) = tmp;
-       }
-}
-
-/* No volatile access, since already used locally */
-static inline
-void subbuffer_id_clear_noref(const struct lttng_ust_lib_ring_buffer_config *config,
-                             unsigned long *id)
-{
-       if (config->mode == RING_BUFFER_OVERWRITE)
-               *id &= ~SB_ID_NOREF_MASK;
-}
-
-/*
- * For overwrite mode, cap the number of subbuffers per buffer to:
- * 2^16 on 32-bit architectures
- * 2^32 on 64-bit architectures
- * This is required to fit in the index part of the ID. Return 0 on success,
- * -EPERM on failure.
- */
-static inline
-int subbuffer_id_check_index(const struct lttng_ust_lib_ring_buffer_config *config,
-                            unsigned long num_subbuf)
-{
-       if (config->mode == RING_BUFFER_OVERWRITE)
-               return (num_subbuf > (1UL << HALF_ULONG_BITS)) ? -EPERM : 0;
-       else
-               return 0;
-}
-
-static inline
-int lib_ring_buffer_backend_get_pages(const struct lttng_ust_lib_ring_buffer_config *config,
-                       struct lttng_ust_lib_ring_buffer_ctx *ctx,
-                       struct lttng_ust_lib_ring_buffer_backend_pages **backend_pages)
-{
-       struct lttng_ust_lib_ring_buffer_backend *bufb = &ctx->buf->backend;
-       struct channel_backend *chanb = &ctx->chan->backend;
-       struct lttng_ust_shm_handle *handle = ctx->handle;
-       size_t sbidx;
-       size_t offset = ctx->buf_offset;
-       struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb;
-       struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
-       unsigned long sb_bindex, id;
-       struct lttng_ust_lib_ring_buffer_backend_pages *_backend_pages;
-
-       offset &= chanb->buf_size - 1;
-       sbidx = offset >> chanb->subbuf_size_order;
-       wsb = shmp_index(handle, bufb->buf_wsb, sbidx);
-       if (caa_unlikely(!wsb))
-               return -1;
-       id = wsb->id;
-       sb_bindex = subbuffer_id_get_index(config, id);
-       rpages = shmp_index(handle, bufb->array, sb_bindex);
-       if (caa_unlikely(!rpages))
-               return -1;
-       CHAN_WARN_ON(ctx->chan,
-                    config->mode == RING_BUFFER_OVERWRITE
-                    && subbuffer_id_is_noref(config, id));
-       _backend_pages = shmp(handle, rpages->shmp);
-       if (caa_unlikely(!_backend_pages))
-               return -1;
-       *backend_pages = _backend_pages;
-       return 0;
-}
-
-/* Get backend pages from cache. */
-static inline
-struct lttng_ust_lib_ring_buffer_backend_pages *
-       lib_ring_buffer_get_backend_pages_from_ctx(const struct lttng_ust_lib_ring_buffer_config *config,
-               struct lttng_ust_lib_ring_buffer_ctx *ctx)
-{
-       if (caa_unlikely(ctx->ctx_len
-                       < sizeof(struct lttng_ust_lib_ring_buffer_ctx)))
-               return NULL;
-       return ctx->backend_pages;
-}
-
-/*
- * The ring buffer can count events recorded and overwritten per buffer,
- * but it is disabled by default due to its performance overhead.
- */
-#ifdef LTTNG_RING_BUFFER_COUNT_EVENTS
-static inline
-void subbuffer_count_record(const struct lttng_ust_lib_ring_buffer_config *config,
-                           const struct lttng_ust_lib_ring_buffer_ctx *ctx,
-                           struct lttng_ust_lib_ring_buffer_backend *bufb,
-                           unsigned long idx, struct lttng_ust_shm_handle *handle)
-{
-       struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
-
-       backend_pages = lib_ring_buffer_get_backend_pages_from_ctx(config, ctx);
-       if (caa_unlikely(!backend_pages)) {
-               if (lib_ring_buffer_backend_get_pages(config, ctx, &backend_pages))
-                       return;
-       }
-       v_inc(config, &backend_pages->records_commit);
-}
-#else /* LTTNG_RING_BUFFER_COUNT_EVENTS */
-static inline
-void subbuffer_count_record(const struct lttng_ust_lib_ring_buffer_config *config,
-                           const struct lttng_ust_lib_ring_buffer_ctx *ctx,
-                           struct lttng_ust_lib_ring_buffer_backend *bufb,
-                           unsigned long idx, struct lttng_ust_shm_handle *handle)
-{
-}
-#endif /* #else LTTNG_RING_BUFFER_COUNT_EVENTS */
-
-/*
- * Reader has exclusive subbuffer access for record consumption. No need to
- * perform the decrement atomically.
- */
-static inline
-void subbuffer_consume_record(const struct lttng_ust_lib_ring_buffer_config *config,
-                             struct lttng_ust_lib_ring_buffer_backend *bufb,
-                             struct lttng_ust_shm_handle *handle)
-{
-       unsigned long sb_bindex;
-       struct channel *chan;
-       struct lttng_ust_lib_ring_buffer_backend_pages_shmp *pages_shmp;
-       struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
-
-       sb_bindex = subbuffer_id_get_index(config, bufb->buf_rsb.id);
-       chan = shmp(handle, bufb->chan);
-       if (!chan)
-               return;
-       pages_shmp = shmp_index(handle, bufb->array, sb_bindex);
-       if (!pages_shmp)
-               return;
-       backend_pages = shmp(handle, pages_shmp->shmp);
-       if (!backend_pages)
-               return;
-       CHAN_WARN_ON(chan, !v_read(config, &backend_pages->records_unread));
-       /* Non-atomic decrement protected by exclusive subbuffer access */
-       _v_dec(config, &backend_pages->records_unread);
-       v_inc(config, &bufb->records_read);
-}
-
-static inline
-unsigned long subbuffer_get_records_count(
-                               const struct lttng_ust_lib_ring_buffer_config *config,
-                               struct lttng_ust_lib_ring_buffer_backend *bufb,
-                               unsigned long idx,
-                               struct lttng_ust_shm_handle *handle)
-{
-       unsigned long sb_bindex;
-       struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb;
-       struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
-       struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
-
-       wsb = shmp_index(handle, bufb->buf_wsb, idx);
-       if (!wsb)
-               return 0;
-       sb_bindex = subbuffer_id_get_index(config, wsb->id);
-       rpages = shmp_index(handle, bufb->array, sb_bindex);
-       if (!rpages)
-               return 0;
-       backend_pages = shmp(handle, rpages->shmp);
-       if (!backend_pages)
-               return 0;
-       return v_read(config, &backend_pages->records_commit);
-}
-
-/*
- * Must be executed at subbuffer delivery when the writer has _exclusive_
- * subbuffer access. See lib_ring_buffer_check_deliver() for details.
- * lib_ring_buffer_get_records_count() must be called to get the records
- * count before this function, because it resets the records_commit
- * count.
- */
-static inline
-unsigned long subbuffer_count_records_overrun(
-                               const struct lttng_ust_lib_ring_buffer_config *config,
-                               struct lttng_ust_lib_ring_buffer_backend *bufb,
-                               unsigned long idx,
-                               struct lttng_ust_shm_handle *handle)
-{
-       unsigned long overruns, sb_bindex;
-       struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb;
-       struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
-       struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
-
-       wsb = shmp_index(handle, bufb->buf_wsb, idx);
-       if (!wsb)
-               return 0;
-       sb_bindex = subbuffer_id_get_index(config, wsb->id);
-       rpages = shmp_index(handle, bufb->array, sb_bindex);
-       if (!rpages)
-               return 0;
-       backend_pages = shmp(handle, rpages->shmp);
-       if (!backend_pages)
-               return 0;
-       overruns = v_read(config, &backend_pages->records_unread);
-       v_set(config, &backend_pages->records_unread,
-             v_read(config, &backend_pages->records_commit));
-       v_set(config, &backend_pages->records_commit, 0);
-
-       return overruns;
-}
-
-static inline
-void subbuffer_set_data_size(const struct lttng_ust_lib_ring_buffer_config *config,
-                            struct lttng_ust_lib_ring_buffer_backend *bufb,
-                            unsigned long idx,
-                            unsigned long data_size,
-                            struct lttng_ust_shm_handle *handle)
-{
-       unsigned long sb_bindex;
-       struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb;
-       struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
-       struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
-
-       wsb = shmp_index(handle, bufb->buf_wsb, idx);
-       if (!wsb)
-               return;
-       sb_bindex = subbuffer_id_get_index(config, wsb->id);
-       rpages = shmp_index(handle, bufb->array, sb_bindex);
-       if (!rpages)
-               return;
-       backend_pages = shmp(handle, rpages->shmp);
-       if (!backend_pages)
-               return;
-       backend_pages->data_size = data_size;
-}
-
-static inline
-unsigned long subbuffer_get_read_data_size(
-                               const struct lttng_ust_lib_ring_buffer_config *config,
-                               struct lttng_ust_lib_ring_buffer_backend *bufb,
-                               struct lttng_ust_shm_handle *handle)
-{
-       unsigned long sb_bindex;
-       struct lttng_ust_lib_ring_buffer_backend_pages_shmp *pages_shmp;
-       struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
-
-       sb_bindex = subbuffer_id_get_index(config, bufb->buf_rsb.id);
-       pages_shmp = shmp_index(handle, bufb->array, sb_bindex);
-       if (!pages_shmp)
-               return 0;
-       backend_pages = shmp(handle, pages_shmp->shmp);
-       if (!backend_pages)
-               return 0;
-       return backend_pages->data_size;
-}
-
-static inline
-unsigned long subbuffer_get_data_size(
-                               const struct lttng_ust_lib_ring_buffer_config *config,
-                               struct lttng_ust_lib_ring_buffer_backend *bufb,
-                               unsigned long idx,
-                               struct lttng_ust_shm_handle *handle)
-{
-       unsigned long sb_bindex;
-       struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb;
-       struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
-       struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
-
-       wsb = shmp_index(handle, bufb->buf_wsb, idx);
-       if (!wsb)
-               return 0;
-       sb_bindex = subbuffer_id_get_index(config, wsb->id);
-       rpages = shmp_index(handle, bufb->array, sb_bindex);
-       if (!rpages)
-               return 0;
-       backend_pages = shmp(handle, rpages->shmp);
-       if (!backend_pages)
-               return 0;
-       return backend_pages->data_size;
-}
-
-static inline
-void subbuffer_inc_packet_count(const struct lttng_ust_lib_ring_buffer_config *config,
-               struct lttng_ust_lib_ring_buffer_backend *bufb,
-               unsigned long idx, struct lttng_ust_shm_handle *handle)
-{
-       struct lttng_ust_lib_ring_buffer_backend_counts *counts;
-
-       counts = shmp_index(handle, bufb->buf_cnt, idx);
-       if (!counts)
-               return;
-       counts->seq_cnt++;
-}
-
-/**
- * lib_ring_buffer_clear_noref - Clear the noref subbuffer flag, called by
- *                               writer.
- */
-static inline
-void lib_ring_buffer_clear_noref(const struct lttng_ust_lib_ring_buffer_config *config,
-                                struct lttng_ust_lib_ring_buffer_backend *bufb,
-                                unsigned long idx,
-                                struct lttng_ust_shm_handle *handle)
-{
-       unsigned long id, new_id;
-       struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb;
-
-       if (config->mode != RING_BUFFER_OVERWRITE)
-               return;
-
-       /*
-        * Performing a volatile access to read the sb_pages, because we want to
-        * read a coherent version of the pointer and the associated noref flag.
-        */
-       wsb = shmp_index(handle, bufb->buf_wsb, idx);
-       if (!wsb)
-               return;
-       id = CMM_ACCESS_ONCE(wsb->id);
-       for (;;) {
-               /* This check is called on the fast path for each record. */
-               if (caa_likely(!subbuffer_id_is_noref(config, id))) {
-                       /*
-                        * Store after load dependency ordering the writes to
-                        * the subbuffer after load and test of the noref flag
-                        * matches the memory barrier implied by the cmpxchg()
-                        * in update_read_sb_index().
-                        */
-                       return; /* Already writing to this buffer */
-               }
-               new_id = id;
-               subbuffer_id_clear_noref(config, &new_id);
-               new_id = uatomic_cmpxchg(&wsb->id, id, new_id);
-               if (caa_likely(new_id == id))
-                       break;
-               id = new_id;
-       }
-}
-
-/**
- * lib_ring_buffer_set_noref_offset - Set the noref subbuffer flag and offset,
- *                                    called by writer.
- */
-static inline
-void lib_ring_buffer_set_noref_offset(const struct lttng_ust_lib_ring_buffer_config *config,
-                                     struct lttng_ust_lib_ring_buffer_backend *bufb,
-                                     unsigned long idx, unsigned long offset,
-                                     struct lttng_ust_shm_handle *handle)
-{
-       struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb;
-       struct channel *chan;
-
-       if (config->mode != RING_BUFFER_OVERWRITE)
-               return;
-
-       wsb = shmp_index(handle, bufb->buf_wsb, idx);
-       if (!wsb)
-               return;
-       /*
-        * Because ring_buffer_set_noref() is only called by a single thread
-        * (the one which updated the cc_sb value), there are no concurrent
-        * updates to take care of: other writers have not updated cc_sb, so
-        * they cannot set the noref flag, and concurrent readers cannot modify
-        * the pointer because the noref flag is not set yet.
-        * The smp_wmb() in ring_buffer_commit() takes care of ordering writes
-        * to the subbuffer before this set noref operation.
-        * subbuffer_set_noref() uses a volatile store to deal with concurrent
-        * readers of the noref flag.
-        */
-       chan = shmp(handle, bufb->chan);
-       if (!chan)
-               return;
-       CHAN_WARN_ON(chan, subbuffer_id_is_noref(config, wsb->id));
-       /*
-        * Memory barrier that ensures counter stores are ordered before set
-        * noref and offset.
-        */
-       cmm_smp_mb();
-       subbuffer_id_set_noref_offset(config, &wsb->id, offset);
-}
-
-/**
- * update_read_sb_index - Read-side subbuffer index update.
- */
-static inline
-int update_read_sb_index(const struct lttng_ust_lib_ring_buffer_config *config,
-                        struct lttng_ust_lib_ring_buffer_backend *bufb,
-                        struct channel_backend *chanb,
-                        unsigned long consumed_idx,
-                        unsigned long consumed_count,
-                        struct lttng_ust_shm_handle *handle)
-{
-       struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb;
-       unsigned long old_id, new_id;
-
-       wsb = shmp_index(handle, bufb->buf_wsb, consumed_idx);
-       if (caa_unlikely(!wsb))
-               return -EPERM;
-
-       if (config->mode == RING_BUFFER_OVERWRITE) {
-               struct channel *chan;
-
-               /*
-                * Exchange the target writer subbuffer with our own unused
-                * subbuffer. No need to use CMM_ACCESS_ONCE() here to read the
-                * old_wpage, because the value read will be confirmed by the
-                * following cmpxchg().
-                */
-               old_id = wsb->id;
-               if (caa_unlikely(!subbuffer_id_is_noref(config, old_id)))
-                       return -EAGAIN;
-               /*
-                * Make sure the offset count we are expecting matches the one
-                * indicated by the writer.
-                */
-               if (caa_unlikely(!subbuffer_id_compare_offset(config, old_id,
-                                                         consumed_count)))
-                       return -EAGAIN;
-               chan = shmp(handle, bufb->chan);
-               if (caa_unlikely(!chan))
-                       return -EPERM;
-               CHAN_WARN_ON(chan, !subbuffer_id_is_noref(config, bufb->buf_rsb.id));
-               subbuffer_id_set_noref_offset(config, &bufb->buf_rsb.id,
-                                             consumed_count);
-               new_id = uatomic_cmpxchg(&wsb->id, old_id, bufb->buf_rsb.id);
-               if (caa_unlikely(old_id != new_id))
-                       return -EAGAIN;
-               bufb->buf_rsb.id = new_id;
-       } else {
-               /* No page exchange, use the writer page directly */
-               bufb->buf_rsb.id = wsb->id;
-       }
-       return 0;
-}
-
-#ifndef inline_memcpy
-#define inline_memcpy(dest, src, n)    memcpy(dest, src, n)
-#endif
-
-static inline __attribute__((always_inline))
-void lttng_inline_memcpy(void *dest, const void *src,
-               unsigned long len)
-{
-       switch (len) {
-       case 1:
-               *(uint8_t *) dest = *(const uint8_t *) src;
-               break;
-       case 2:
-               *(uint16_t *) dest = *(const uint16_t *) src;
-               break;
-       case 4:
-               *(uint32_t *) dest = *(const uint32_t *) src;
-               break;
-       case 8:
-               *(uint64_t *) dest = *(const uint64_t *) src;
-               break;
-       default:
-               inline_memcpy(dest, src, len);
-       }
-}
-
-/*
- * Use the architecture-specific memcpy implementation for constant-sized
- * inputs, but rely on an inline memcpy for length statically unknown.
- * The function call to memcpy is just way too expensive for a fast path.
- */
-#define lib_ring_buffer_do_copy(config, dest, src, len)                \
-do {                                                           \
-       size_t __len = (len);                                   \
-       if (__builtin_constant_p(len))                          \
-               memcpy(dest, src, __len);                       \
-       else                                                    \
-               lttng_inline_memcpy(dest, src, __len);          \
-} while (0)
-
-/*
- * write len bytes to dest with c
- */
-static inline
-void lib_ring_buffer_do_memset(char *dest, int c, unsigned long len)
-{
-       unsigned long i;
-
-       for (i = 0; i < len; i++)
-               dest[i] = c;
-}
-
-/* arch-agnostic implementation */
-
-static inline int lttng_ust_fls(unsigned int x)
-{
-       int r = 32;
-
-       if (!x)
-               return 0;
-       if (!(x & 0xFFFF0000U)) {
-               x <<= 16;
-               r -= 16;
-       }
-       if (!(x & 0xFF000000U)) {
-               x <<= 8;
-               r -= 8;
-       }
-       if (!(x & 0xF0000000U)) {
-               x <<= 4;
-               r -= 4;
-       }
-       if (!(x & 0xC0000000U)) {
-               x <<= 2;
-               r -= 2;
-       }
-       if (!(x & 0x80000000U)) {
-               /* No need to bit shift on last operation */
-               r -= 1;
-       }
-       return r;
-}
-
-static inline int get_count_order(unsigned int count)
-{
-       int order;
-
-       order = lttng_ust_fls(count) - 1;
-       if (count & (count - 1))
-               order++;
-       return order;
-}
-
-#endif /* _LTTNG_RING_BUFFER_BACKEND_INTERNAL_H */
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