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#ifndef _LTTNG_RING_BUFFER_BACKEND_INTERNAL_H
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#define _LTTNG_RING_BUFFER_BACKEND_INTERNAL_H
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/*
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* libringbuffer/backend_internal.h
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*
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* Ring buffer backend (internal helpers).
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*
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* Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; only
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* version 2.1 of the License.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <unistd.h>
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#include <urcu/compiler.h>
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#include <lttng/ringbuffer-config.h>
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#include "backend_types.h"
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#include "frontend_types.h"
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#include "shm.h"
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/* Ring buffer backend API presented to the frontend */
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/* Ring buffer and channel backend create/free */
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int lib_ring_buffer_backend_create(struct lttng_ust_lib_ring_buffer_backend *bufb,
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struct channel_backend *chan, int cpu,
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struct lttng_ust_shm_handle *handle,
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struct shm_object *shmobj);
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void channel_backend_unregister_notifiers(struct channel_backend *chanb);
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void lib_ring_buffer_backend_free(struct lttng_ust_lib_ring_buffer_backend *bufb);
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int channel_backend_init(struct channel_backend *chanb,
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const char *name,
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const struct lttng_ust_lib_ring_buffer_config *config,
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size_t subbuf_size,
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size_t num_subbuf, struct lttng_ust_shm_handle *handle,
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const int *stream_fds);
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void channel_backend_free(struct channel_backend *chanb,
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struct lttng_ust_shm_handle *handle);
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void lib_ring_buffer_backend_reset(struct lttng_ust_lib_ring_buffer_backend *bufb,
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struct lttng_ust_shm_handle *handle);
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void channel_backend_reset(struct channel_backend *chanb);
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int lib_ring_buffer_backend_init(void);
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void lib_ring_buffer_backend_exit(void);
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extern void _lib_ring_buffer_write(struct lttng_ust_lib_ring_buffer_backend *bufb,
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size_t offset, const void *src, size_t len,
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ssize_t pagecpy);
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/*
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* Subbuffer ID bits for overwrite mode. Need to fit within a single word to be
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* exchanged atomically.
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*
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* Top half word, except lowest bit, belongs to "offset", which is used to keep
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* to count the produced buffers. For overwrite mode, this provides the
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* consumer with the capacity to read subbuffers in order, handling the
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* situation where producers would write up to 2^15 buffers (or 2^31 for 64-bit
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* systems) concurrently with a single execution of get_subbuf (between offset
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* sampling and subbuffer ID exchange).
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*/
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#define HALF_ULONG_BITS (CAA_BITS_PER_LONG >> 1)
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#define SB_ID_OFFSET_SHIFT (HALF_ULONG_BITS + 1)
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#define SB_ID_OFFSET_COUNT (1UL << SB_ID_OFFSET_SHIFT)
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#define SB_ID_OFFSET_MASK (~(SB_ID_OFFSET_COUNT - 1))
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/*
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* Lowest bit of top word half belongs to noref. Used only for overwrite mode.
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*/
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#define SB_ID_NOREF_SHIFT (SB_ID_OFFSET_SHIFT - 1)
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#define SB_ID_NOREF_COUNT (1UL << SB_ID_NOREF_SHIFT)
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#define SB_ID_NOREF_MASK SB_ID_NOREF_COUNT
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/*
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* In overwrite mode: lowest half of word is used for index.
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* Limit of 2^16 subbuffers per buffer on 32-bit, 2^32 on 64-bit.
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* In producer-consumer mode: whole word used for index.
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*/
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#define SB_ID_INDEX_SHIFT 0
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#define SB_ID_INDEX_COUNT (1UL << SB_ID_INDEX_SHIFT)
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#define SB_ID_INDEX_MASK (SB_ID_NOREF_COUNT - 1)
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/*
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* Construct the subbuffer id from offset, index and noref. Use only the index
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* for producer-consumer mode (offset and noref are only used in overwrite
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* mode).
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*/
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static inline
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unsigned long subbuffer_id(const struct lttng_ust_lib_ring_buffer_config *config,
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unsigned long offset, unsigned long noref,
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unsigned long index)
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{
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if (config->mode == RING_BUFFER_OVERWRITE)
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return (offset << SB_ID_OFFSET_SHIFT)
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| (noref << SB_ID_NOREF_SHIFT)
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| index;
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else
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return index;
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}
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/*
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* Compare offset with the offset contained within id. Return 1 if the offset
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* bits are identical, else 0.
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*/
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static inline
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int subbuffer_id_compare_offset(const struct lttng_ust_lib_ring_buffer_config *config,
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unsigned long id, unsigned long offset)
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{
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return (id & SB_ID_OFFSET_MASK) == (offset << SB_ID_OFFSET_SHIFT);
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}
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static inline
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unsigned long subbuffer_id_get_index(const struct lttng_ust_lib_ring_buffer_config *config,
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unsigned long id)
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{
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if (config->mode == RING_BUFFER_OVERWRITE)
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return id & SB_ID_INDEX_MASK;
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else
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return id;
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}
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static inline
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unsigned long subbuffer_id_is_noref(const struct lttng_ust_lib_ring_buffer_config *config,
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unsigned long id)
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{
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if (config->mode == RING_BUFFER_OVERWRITE)
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return !!(id & SB_ID_NOREF_MASK);
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else
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return 1;
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}
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/*
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* Only used by reader on subbuffer ID it has exclusive access to. No volatile
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* needed.
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*/
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static inline
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void subbuffer_id_set_noref(const struct lttng_ust_lib_ring_buffer_config *config,
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unsigned long *id)
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{
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if (config->mode == RING_BUFFER_OVERWRITE)
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*id |= SB_ID_NOREF_MASK;
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}
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static inline
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void subbuffer_id_set_noref_offset(const struct lttng_ust_lib_ring_buffer_config *config,
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unsigned long *id, unsigned long offset)
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{
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unsigned long tmp;
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if (config->mode == RING_BUFFER_OVERWRITE) {
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tmp = *id;
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tmp &= ~SB_ID_OFFSET_MASK;
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tmp |= offset << SB_ID_OFFSET_SHIFT;
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tmp |= SB_ID_NOREF_MASK;
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/* Volatile store, read concurrently by readers. */
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CMM_ACCESS_ONCE(*id) = tmp;
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}
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}
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/* No volatile access, since already used locally */
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static inline
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void subbuffer_id_clear_noref(const struct lttng_ust_lib_ring_buffer_config *config,
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unsigned long *id)
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{
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if (config->mode == RING_BUFFER_OVERWRITE)
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*id &= ~SB_ID_NOREF_MASK;
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}
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/*
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* For overwrite mode, cap the number of subbuffers per buffer to:
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* 2^16 on 32-bit architectures
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* 2^32 on 64-bit architectures
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* This is required to fit in the index part of the ID. Return 0 on success,
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* -EPERM on failure.
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*/
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static inline
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int subbuffer_id_check_index(const struct lttng_ust_lib_ring_buffer_config *config,
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unsigned long num_subbuf)
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{
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if (config->mode == RING_BUFFER_OVERWRITE)
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return (num_subbuf > (1UL << HALF_ULONG_BITS)) ? -EPERM : 0;
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else
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return 0;
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}
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static inline
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void subbuffer_count_record(const struct lttng_ust_lib_ring_buffer_config *config,
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struct lttng_ust_lib_ring_buffer_backend *bufb,
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unsigned long idx, struct lttng_ust_shm_handle *handle)
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{
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unsigned long sb_bindex;
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sb_bindex = subbuffer_id_get_index(config, shmp_index(handle, bufb->buf_wsb, idx)->id);
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v_inc(config, &shmp(handle, shmp_index(handle, bufb->array, sb_bindex)->shmp)->records_commit);
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}
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/*
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* Reader has exclusive subbuffer access for record consumption. No need to
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* perform the decrement atomically.
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*/
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static inline
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void subbuffer_consume_record(const struct lttng_ust_lib_ring_buffer_config *config,
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struct lttng_ust_lib_ring_buffer_backend *bufb,
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struct lttng_ust_shm_handle *handle)
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{
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unsigned long sb_bindex;
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sb_bindex = subbuffer_id_get_index(config, bufb->buf_rsb.id);
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CHAN_WARN_ON(shmp(handle, bufb->chan),
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!v_read(config, &shmp(handle, shmp_index(handle, bufb->array, sb_bindex)->shmp)->records_unread));
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/* Non-atomic decrement protected by exclusive subbuffer access */
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_v_dec(config, &shmp(handle, shmp_index(handle, bufb->array, sb_bindex)->shmp)->records_unread);
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v_inc(config, &bufb->records_read);
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}
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static inline
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unsigned long subbuffer_get_records_count(
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const struct lttng_ust_lib_ring_buffer_config *config,
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struct lttng_ust_lib_ring_buffer_backend *bufb,
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unsigned long idx,
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struct lttng_ust_shm_handle *handle)
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{
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unsigned long sb_bindex;
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sb_bindex = subbuffer_id_get_index(config, shmp_index(handle, bufb->buf_wsb, idx)->id);
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return v_read(config, &shmp(handle, shmp_index(handle, bufb->array, sb_bindex)->shmp)->records_commit);
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}
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/*
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* Must be executed at subbuffer delivery when the writer has _exclusive_
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* subbuffer access. See lib_ring_buffer_check_deliver() for details.
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* lib_ring_buffer_get_records_count() must be called to get the records
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* count before this function, because it resets the records_commit
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* count.
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*/
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static inline
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unsigned long subbuffer_count_records_overrun(
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const struct lttng_ust_lib_ring_buffer_config *config,
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struct lttng_ust_lib_ring_buffer_backend *bufb,
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unsigned long idx,
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struct lttng_ust_shm_handle *handle)
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{
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struct lttng_ust_lib_ring_buffer_backend_pages_shmp *pages;
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unsigned long overruns, sb_bindex;
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sb_bindex = subbuffer_id_get_index(config, shmp_index(handle, bufb->buf_wsb, idx)->id);
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pages = shmp_index(handle, bufb->array, sb_bindex);
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overruns = v_read(config, &shmp(handle, pages->shmp)->records_unread);
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v_set(config, &shmp(handle, pages->shmp)->records_unread,
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v_read(config, &shmp(handle, pages->shmp)->records_commit));
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v_set(config, &shmp(handle, pages->shmp)->records_commit, 0);
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return overruns;
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}
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static inline
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void subbuffer_set_data_size(const struct lttng_ust_lib_ring_buffer_config *config,
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struct lttng_ust_lib_ring_buffer_backend *bufb,
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unsigned long idx,
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unsigned long data_size,
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struct lttng_ust_shm_handle *handle)
|
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c04fcb |
{
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c04fcb |
struct lttng_ust_lib_ring_buffer_backend_pages_shmp *pages;
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c04fcb |
unsigned long sb_bindex;
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c04fcb |
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c04fcb |
sb_bindex = subbuffer_id_get_index(config, shmp_index(handle, bufb->buf_wsb, idx)->id);
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c04fcb |
pages = shmp_index(handle, bufb->array, sb_bindex);
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c04fcb |
shmp(handle, pages->shmp)->data_size = data_size;
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c04fcb |
}
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c04fcb |
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c04fcb |
static inline
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c04fcb |
unsigned long subbuffer_get_read_data_size(
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c04fcb |
const struct lttng_ust_lib_ring_buffer_config *config,
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c04fcb |
struct lttng_ust_lib_ring_buffer_backend *bufb,
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c04fcb |
struct lttng_ust_shm_handle *handle)
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c04fcb |
{
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c04fcb |
struct lttng_ust_lib_ring_buffer_backend_pages_shmp *pages;
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c04fcb |
unsigned long sb_bindex;
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c04fcb |
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c04fcb |
sb_bindex = subbuffer_id_get_index(config, bufb->buf_rsb.id);
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c04fcb |
pages = shmp_index(handle, bufb->array, sb_bindex);
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c04fcb |
return shmp(handle, pages->shmp)->data_size;
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c04fcb |
}
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c04fcb |
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c04fcb |
static inline
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c04fcb |
unsigned long subbuffer_get_data_size(
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c04fcb |
const struct lttng_ust_lib_ring_buffer_config *config,
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c04fcb |
struct lttng_ust_lib_ring_buffer_backend *bufb,
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c04fcb |
unsigned long idx,
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c04fcb |
struct lttng_ust_shm_handle *handle)
|
|
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c04fcb |
{
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|
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c04fcb |
struct lttng_ust_lib_ring_buffer_backend_pages_shmp *pages;
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|
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c04fcb |
unsigned long sb_bindex;
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|
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c04fcb |
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c04fcb |
sb_bindex = subbuffer_id_get_index(config, shmp_index(handle, bufb->buf_wsb, idx)->id);
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|
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c04fcb |
pages = shmp_index(handle, bufb->array, sb_bindex);
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c04fcb |
return shmp(handle, pages->shmp)->data_size;
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c04fcb |
}
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c04fcb |
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c04fcb |
static inline
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c04fcb |
void subbuffer_inc_packet_count(const struct lttng_ust_lib_ring_buffer_config *config,
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c04fcb |
struct lttng_ust_lib_ring_buffer_backend *bufb,
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c04fcb |
unsigned long idx, struct lttng_ust_shm_handle *handle)
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|
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c04fcb |
{
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c04fcb |
shmp_index(handle, bufb->buf_cnt, idx)->seq_cnt++;
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c04fcb |
}
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c04fcb |
|
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c04fcb |
/**
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c04fcb |
* lib_ring_buffer_clear_noref - Clear the noref subbuffer flag, called by
|
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c04fcb |
* writer.
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|
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c04fcb |
*/
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c04fcb |
static inline
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c04fcb |
void lib_ring_buffer_clear_noref(const struct lttng_ust_lib_ring_buffer_config *config,
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c04fcb |
struct lttng_ust_lib_ring_buffer_backend *bufb,
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|
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c04fcb |
unsigned long idx,
|
|
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c04fcb |
struct lttng_ust_shm_handle *handle)
|
|
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c04fcb |
{
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|
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c04fcb |
unsigned long id, new_id;
|
|
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c04fcb |
|
|
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c04fcb |
if (config->mode != RING_BUFFER_OVERWRITE)
|
|
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c04fcb |
return;
|
|
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c04fcb |
|
|
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c04fcb |
/*
|
|
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c04fcb |
* Performing a volatile access to read the sb_pages, because we want to
|
|
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c04fcb |
* read a coherent version of the pointer and the associated noref flag.
|
|
Packit |
c04fcb |
*/
|
|
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c04fcb |
id = CMM_ACCESS_ONCE(shmp_index(handle, bufb->buf_wsb, idx)->id);
|
|
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c04fcb |
for (;;) {
|
|
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c04fcb |
/* This check is called on the fast path for each record. */
|
|
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c04fcb |
if (caa_likely(!subbuffer_id_is_noref(config, id))) {
|
|
Packit |
c04fcb |
/*
|
|
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c04fcb |
* Store after load dependency ordering the writes to
|
|
Packit |
c04fcb |
* the subbuffer after load and test of the noref flag
|
|
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c04fcb |
* matches the memory barrier implied by the cmpxchg()
|
|
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c04fcb |
* in update_read_sb_index().
|
|
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c04fcb |
*/
|
|
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c04fcb |
return; /* Already writing to this buffer */
|
|
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c04fcb |
}
|
|
Packit |
c04fcb |
new_id = id;
|
|
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c04fcb |
subbuffer_id_clear_noref(config, &new_id);
|
|
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c04fcb |
new_id = uatomic_cmpxchg(&shmp_index(handle, bufb->buf_wsb, idx)->id, id, new_id);
|
|
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c04fcb |
if (caa_likely(new_id == id))
|
|
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c04fcb |
break;
|
|
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c04fcb |
id = new_id;
|
|
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c04fcb |
}
|
|
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c04fcb |
}
|
|
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c04fcb |
|
|
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c04fcb |
/**
|
|
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c04fcb |
* lib_ring_buffer_set_noref_offset - Set the noref subbuffer flag and offset,
|
|
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c04fcb |
* called by writer.
|
|
Packit |
c04fcb |
*/
|
|
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c04fcb |
static inline
|
|
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c04fcb |
void lib_ring_buffer_set_noref_offset(const struct lttng_ust_lib_ring_buffer_config *config,
|
|
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c04fcb |
struct lttng_ust_lib_ring_buffer_backend *bufb,
|
|
Packit |
c04fcb |
unsigned long idx, unsigned long offset,
|
|
Packit |
c04fcb |
struct lttng_ust_shm_handle *handle)
|
|
Packit |
c04fcb |
{
|
|
Packit |
c04fcb |
if (config->mode != RING_BUFFER_OVERWRITE)
|
|
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c04fcb |
return;
|
|
Packit |
c04fcb |
|
|
Packit |
c04fcb |
/*
|
|
Packit |
c04fcb |
* Because ring_buffer_set_noref() is only called by a single thread
|
|
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c04fcb |
* (the one which updated the cc_sb value), there are no concurrent
|
|
Packit |
c04fcb |
* updates to take care of: other writers have not updated cc_sb, so
|
|
Packit |
c04fcb |
* they cannot set the noref flag, and concurrent readers cannot modify
|
|
Packit |
c04fcb |
* the pointer because the noref flag is not set yet.
|
|
Packit |
c04fcb |
* The smp_wmb() in ring_buffer_commit() takes care of ordering writes
|
|
Packit |
c04fcb |
* to the subbuffer before this set noref operation.
|
|
Packit |
c04fcb |
* subbuffer_set_noref() uses a volatile store to deal with concurrent
|
|
Packit |
c04fcb |
* readers of the noref flag.
|
|
Packit |
c04fcb |
*/
|
|
Packit |
c04fcb |
CHAN_WARN_ON(shmp(handle, bufb->chan),
|
|
Packit |
c04fcb |
subbuffer_id_is_noref(config, shmp_index(handle, bufb->buf_wsb, idx)->id));
|
|
Packit |
c04fcb |
/*
|
|
Packit |
c04fcb |
* Memory barrier that ensures counter stores are ordered before set
|
|
Packit |
c04fcb |
* noref and offset.
|
|
Packit |
c04fcb |
*/
|
|
Packit |
c04fcb |
cmm_smp_mb();
|
|
Packit |
c04fcb |
subbuffer_id_set_noref_offset(config, &shmp_index(handle, bufb->buf_wsb, idx)->id, offset);
|
|
Packit |
c04fcb |
}
|
|
Packit |
c04fcb |
|
|
Packit |
c04fcb |
/**
|
|
Packit |
c04fcb |
* update_read_sb_index - Read-side subbuffer index update.
|
|
Packit |
c04fcb |
*/
|
|
Packit |
c04fcb |
static inline
|
|
Packit |
c04fcb |
int update_read_sb_index(const struct lttng_ust_lib_ring_buffer_config *config,
|
|
Packit |
c04fcb |
struct lttng_ust_lib_ring_buffer_backend *bufb,
|
|
Packit |
c04fcb |
struct channel_backend *chanb,
|
|
Packit |
c04fcb |
unsigned long consumed_idx,
|
|
Packit |
c04fcb |
unsigned long consumed_count,
|
|
Packit |
c04fcb |
struct lttng_ust_shm_handle *handle)
|
|
Packit |
c04fcb |
{
|
|
Packit |
c04fcb |
unsigned long old_id, new_id;
|
|
Packit |
c04fcb |
|
|
Packit |
c04fcb |
if (config->mode == RING_BUFFER_OVERWRITE) {
|
|
Packit |
c04fcb |
/*
|
|
Packit |
c04fcb |
* Exchange the target writer subbuffer with our own unused
|
|
Packit |
c04fcb |
* subbuffer. No need to use CMM_ACCESS_ONCE() here to read the
|
|
Packit |
c04fcb |
* old_wpage, because the value read will be confirmed by the
|
|
Packit |
c04fcb |
* following cmpxchg().
|
|
Packit |
c04fcb |
*/
|
|
Packit |
c04fcb |
old_id = shmp_index(handle, bufb->buf_wsb, consumed_idx)->id;
|
|
Packit |
c04fcb |
if (caa_unlikely(!subbuffer_id_is_noref(config, old_id)))
|
|
Packit |
c04fcb |
return -EAGAIN;
|
|
Packit |
c04fcb |
/*
|
|
Packit |
c04fcb |
* Make sure the offset count we are expecting matches the one
|
|
Packit |
c04fcb |
* indicated by the writer.
|
|
Packit |
c04fcb |
*/
|
|
Packit |
c04fcb |
if (caa_unlikely(!subbuffer_id_compare_offset(config, old_id,
|
|
Packit |
c04fcb |
consumed_count)))
|
|
Packit |
c04fcb |
return -EAGAIN;
|
|
Packit |
c04fcb |
CHAN_WARN_ON(shmp(handle, bufb->chan),
|
|
Packit |
c04fcb |
!subbuffer_id_is_noref(config, bufb->buf_rsb.id));
|
|
Packit |
c04fcb |
subbuffer_id_set_noref_offset(config, &bufb->buf_rsb.id,
|
|
Packit |
c04fcb |
consumed_count);
|
|
Packit |
c04fcb |
new_id = uatomic_cmpxchg(&shmp_index(handle, bufb->buf_wsb, consumed_idx)->id, old_id,
|
|
Packit |
c04fcb |
bufb->buf_rsb.id);
|
|
Packit |
c04fcb |
if (caa_unlikely(old_id != new_id))
|
|
Packit |
c04fcb |
return -EAGAIN;
|
|
Packit |
c04fcb |
bufb->buf_rsb.id = new_id;
|
|
Packit |
c04fcb |
} else {
|
|
Packit |
c04fcb |
/* No page exchange, use the writer page directly */
|
|
Packit |
c04fcb |
bufb->buf_rsb.id = shmp_index(handle, bufb->buf_wsb, consumed_idx)->id;
|
|
Packit |
c04fcb |
}
|
|
Packit |
c04fcb |
return 0;
|
|
Packit |
c04fcb |
}
|
|
Packit |
c04fcb |
|
|
Packit |
c04fcb |
#ifndef inline_memcpy
|
|
Packit |
c04fcb |
#define inline_memcpy(dest, src, n) memcpy(dest, src, n)
|
|
Packit |
c04fcb |
#endif
|
|
Packit |
c04fcb |
|
|
Packit |
c04fcb |
/*
|
|
Packit |
c04fcb |
* Use the architecture-specific memcpy implementation for constant-sized
|
|
Packit |
c04fcb |
* inputs, but rely on an inline memcpy for length statically unknown.
|
|
Packit |
c04fcb |
* The function call to memcpy is just way too expensive for a fast path.
|
|
Packit |
c04fcb |
*/
|
|
Packit |
c04fcb |
#define lib_ring_buffer_do_copy(config, dest, src, len) \
|
|
Packit |
c04fcb |
do { \
|
|
Packit |
c04fcb |
size_t __len = (len); \
|
|
Packit |
c04fcb |
if (__builtin_constant_p(len)) \
|
|
Packit |
c04fcb |
memcpy(dest, src, __len); \
|
|
Packit |
c04fcb |
else \
|
|
Packit |
c04fcb |
inline_memcpy(dest, src, __len); \
|
|
Packit |
c04fcb |
} while (0)
|
|
Packit |
c04fcb |
|
|
Packit |
c04fcb |
/*
|
|
Packit |
c04fcb |
* write len bytes to dest with c
|
|
Packit |
c04fcb |
*/
|
|
Packit |
c04fcb |
static inline
|
|
Packit |
c04fcb |
void lib_ring_buffer_do_memset(char *dest, int c, unsigned long len)
|
|
Packit |
c04fcb |
{
|
|
Packit |
c04fcb |
unsigned long i;
|
|
Packit |
c04fcb |
|
|
Packit |
c04fcb |
for (i = 0; i < len; i++)
|
|
Packit |
c04fcb |
dest[i] = c;
|
|
Packit |
c04fcb |
}
|
|
Packit |
c04fcb |
|
|
Packit |
c04fcb |
/* arch-agnostic implementation */
|
|
Packit |
c04fcb |
|
|
Packit |
c04fcb |
static inline int lttng_ust_fls(unsigned int x)
|
|
Packit |
c04fcb |
{
|
|
Packit |
c04fcb |
int r = 32;
|
|
Packit |
c04fcb |
|
|
Packit |
c04fcb |
if (!x)
|
|
Packit |
c04fcb |
return 0;
|
|
Packit |
c04fcb |
if (!(x & 0xFFFF0000U)) {
|
|
Packit |
c04fcb |
x <<= 16;
|
|
Packit |
c04fcb |
r -= 16;
|
|
Packit |
c04fcb |
}
|
|
Packit |
c04fcb |
if (!(x & 0xFF000000U)) {
|
|
Packit |
c04fcb |
x <<= 8;
|
|
Packit |
c04fcb |
r -= 8;
|
|
Packit |
c04fcb |
}
|
|
Packit |
c04fcb |
if (!(x & 0xF0000000U)) {
|
|
Packit |
c04fcb |
x <<= 4;
|
|
Packit |
c04fcb |
r -= 4;
|
|
Packit |
c04fcb |
}
|
|
Packit |
c04fcb |
if (!(x & 0xC0000000U)) {
|
|
Packit |
c04fcb |
x <<= 2;
|
|
Packit |
c04fcb |
r -= 2;
|
|
Packit |
c04fcb |
}
|
|
Packit |
c04fcb |
if (!(x & 0x80000000U)) {
|
|
Packit |
c04fcb |
/* No need to bit shift on last operation */
|
|
Packit |
c04fcb |
r -= 1;
|
|
Packit |
c04fcb |
}
|
|
Packit |
c04fcb |
return r;
|
|
Packit |
c04fcb |
}
|
|
Packit |
c04fcb |
|
|
Packit |
c04fcb |
static inline int get_count_order(unsigned int count)
|
|
Packit |
c04fcb |
{
|
|
Packit |
c04fcb |
int order;
|
|
Packit |
c04fcb |
|
|
Packit |
c04fcb |
order = lttng_ust_fls(count) - 1;
|
|
Packit |
c04fcb |
if (count & (count - 1))
|
|
Packit |
c04fcb |
order++;
|
|
Packit |
c04fcb |
return order;
|
|
Packit |
c04fcb |
}
|
|
Packit |
c04fcb |
|
|
Packit |
c04fcb |
#endif /* _LTTNG_RING_BUFFER_BACKEND_INTERNAL_H */
|