1 files changed, 67 insertions, 0 deletions
diff --git a/lib/trace.h b/lib/trace.h
new file mode 100644
index 0000000..a30f53c
--- /dev/null
+++ b/lib/trace.h
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+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Tracing macros
+ *
+ * Wraps tracepoint macros for different tracing systems to allow switching
+ * between them at compile time.
+ *
+ * This should not be included directly by source files wishing to provide
+ * tracepoints. Instead, write a header that defines LTTng tracepoints and
+ * which includes this header, and include your new header in your source. USDT
+ * probes do not need tracepoint definitions, but are less capable than LTTng
+ * tracepoints.
+ *
+ * Copyright (C) 2020  NVIDIA Corporation
+ * Quentin Young
+ */
+
+#ifndef _TRACE_H_
+#define _TRACE_H_
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif /* HAVE_CONFIG_H */
+
+/*
+ * Provided here:
+ * - frrtrace(n, provider, name, ...args...)
+ * - frrtrace_enabled(provider, name)
+ * - frrtracelog(level, msg, ...)
+ *
+ * Use frrtrace() to define tracepoints. n is the number of arguments; this is
+ * needed because USDT probe definitions use DTRACE_PROBEn macros, so the
+ * number of args must be passed in order to expand the correct macro.
+ *
+ * frrtrace_enabled() maps to tracepoint_enabled() under LTTng and is always
+ * true when using USDT. In the future it could be mapped to USDT semaphores
+ * but this is not implemented at present.
+ *
+ * frrtracelog() maps to tracelog() under LTTng and should only be used in zlog
+ * core code, to propagate zlog messages to LTTng. It expands to nothing
+ * otherwise.
+ */
+
+#if defined(HAVE_LTTNG)
+
+#define frrtrace(nargs, provider, name, ...) \
+	tracepoint(provider, name, ## __VA_ARGS__)
+#define frrtrace_enabled(...) tracepoint_enabled(__VA_ARGS__)
+#define frrtracelog(...) tracelog(__VA_ARGS__)
+
+#elif defined(HAVE_USDT)
+
+#include "sys/sdt.h"
+
+#define frrtrace(nargs, provider, name, ...) \
+	DTRACE_PROBE##nargs(provider, name, ## __VA_ARGS__)
+#define frrtrace_enabled(...) true
+#define frrtracelog(...)
+
+#else
+
+#define frrtrace(nargs, provider, name, ...) (void)0
+#define frrtrace_enabled(...) false
+#define frrtracelog(...) (void)0
+
+#endif
+
+#endif /* _TRACE_H_ */