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/* SPDX-License-Identifier: (GPL-2.0-only OR LGPL-2.1-only)
*
* ringbuffer/vatomic.h
*
* Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
*/
#ifndef _LIB_RING_BUFFER_VATOMIC_H
#define _LIB_RING_BUFFER_VATOMIC_H
#include <asm/atomic.h>
#include <asm/local.h>
/*
* Same data type (long) accessed differently depending on configuration.
* v field is for non-atomic access (protected by mutual exclusion).
* In the fast-path, the ring_buffer_config structure is constant, so the
* compiler can statically select the appropriate branch.
* local_t is used for per-cpu and per-thread buffers.
* atomic_long_t is used for per-channel shared buffers.
*/
union v_atomic {
local_t l;
atomic_long_t a;
long v;
};
static inline
long v_read(const struct lttng_kernel_ring_buffer_config *config, union v_atomic *v_a)
{
if (config->sync == RING_BUFFER_SYNC_PER_CPU)
return local_read(&v_a->l);
else
return atomic_long_read(&v_a->a);
}
static inline
void v_set(const struct lttng_kernel_ring_buffer_config *config, union v_atomic *v_a,
long v)
{
if (config->sync == RING_BUFFER_SYNC_PER_CPU)
local_set(&v_a->l, v);
else
atomic_long_set(&v_a->a, v);
}
static inline
void v_add(const struct lttng_kernel_ring_buffer_config *config, long v, union v_atomic *v_a)
{
if (config->sync == RING_BUFFER_SYNC_PER_CPU)
local_add(v, &v_a->l);
else
atomic_long_add(v, &v_a->a);
}
static inline
void v_inc(const struct lttng_kernel_ring_buffer_config *config, union v_atomic *v_a)
{
if (config->sync == RING_BUFFER_SYNC_PER_CPU)
local_inc(&v_a->l);
else
atomic_long_inc(&v_a->a);
}
/*
* Non-atomic decrement. Only used by reader, apply to reader-owned subbuffer.
*/
static inline
void _v_dec(const struct lttng_kernel_ring_buffer_config *config, union v_atomic *v_a)
{
--v_a->v;
}
static inline
long v_cmpxchg(const struct lttng_kernel_ring_buffer_config *config, union v_atomic *v_a,
long old, long _new)
{
if (config->sync == RING_BUFFER_SYNC_PER_CPU)
return local_cmpxchg(&v_a->l, old, _new);
else
return atomic_long_cmpxchg(&v_a->a, old, _new);
}
#endif /* _LIB_RING_BUFFER_VATOMIC_H */
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