X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=include%2Flttng%2Fvatomic.h;fp=include%2Flttng%2Fvatomic.h;h=a477d4c95aef854935a9568d904547efb9a5713b;hb=4318ae1be57eb7983ab4857a7a8eeb4a030a8216;hp=0000000000000000000000000000000000000000;hpb=d4419b81b243bc3a6bdd4a09b3ca2216d044a1c7;p=ust.git

diff --git a/include/lttng/vatomic.h b/include/lttng/vatomic.h
new file mode 100644
index 0000000..a477d4c
--- /dev/null
+++ b/include/lttng/vatomic.h
@@ -0,0 +1,74 @@
+#ifndef _LINUX_RING_BUFFER_VATOMIC_H
+#define _LINUX_RING_BUFFER_VATOMIC_H
+
+/*
+ * linux/ringbuffer/vatomic.h
+ *
+ * Copyright (C) 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <assert.h>
+#include <urcu/uatomic.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 globally shared buffers.
+ */
+union v_atomic {
+	long a;	/* accessed through uatomic */
+	long v;
+};
+
+static inline
+long v_read(const struct lttng_ust_lib_ring_buffer_config *config, union v_atomic *v_a)
+{
+	assert(config->sync != RING_BUFFER_SYNC_PER_CPU);
+	return uatomic_read(&v_a->a);
+}
+
+static inline
+void v_set(const struct lttng_ust_lib_ring_buffer_config *config, union v_atomic *v_a,
+	   long v)
+{
+	assert(config->sync != RING_BUFFER_SYNC_PER_CPU);
+	uatomic_set(&v_a->a, v);
+}
+
+static inline
+void v_add(const struct lttng_ust_lib_ring_buffer_config *config, long v, union v_atomic *v_a)
+{
+	assert(config->sync != RING_BUFFER_SYNC_PER_CPU);
+	uatomic_add(&v_a->a, v);
+}
+
+static inline
+void v_inc(const struct lttng_ust_lib_ring_buffer_config *config, union v_atomic *v_a)
+{
+	assert(config->sync != RING_BUFFER_SYNC_PER_CPU);
+	uatomic_inc(&v_a->a);
+}
+
+/*
+ * Non-atomic decrement. Only used by reader, apply to reader-owned subbuffer.
+ */
+static inline
+void _v_dec(const struct lttng_ust_lib_ring_buffer_config *config, union v_atomic *v_a)
+{
+	--v_a->v;
+}
+
+static inline
+long v_cmpxchg(const struct lttng_ust_lib_ring_buffer_config *config, union v_atomic *v_a,
+	       long old, long _new)
+{
+	assert(config->sync != RING_BUFFER_SYNC_PER_CPU);
+	return uatomic_cmpxchg(&v_a->a, old, _new);
+}
+
+#endif /* _LINUX_RING_BUFFER_VATOMIC_H */