Commit 7cb2e3ee authored by Steven Rostedt's avatar Steven Rostedt Committed by Steven Rostedt

tracing: add comments to explain TRACE_EVENT out of protection

The commit:
  commit 5ac35daa
  Author: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
  tracing/events: fix the include file dependencies

Moved the TRACE_EVENT out of the ifdef protection of tracepoints.h
but uses the define of TRACE_EVENT itself as protection. This patch
adds comments to explain why.
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 5ac35daa
......@@ -180,7 +180,15 @@ static inline void tracepoint_synchronize_unregister(void)
}
#define PARAMS(args...) args
#endif
#endif /* _LINUX_TRACEPOINT_H */
/*
* Note: we keep the TRACE_EVENT outside the include file ifdef protection.
* This is due to the way trace events work. If a file includes two
* trace event headers under one "CREATE_TRACE_POINTS" the first include
* will override the TRACE_EVENT and break the second include.
*/
#ifndef TRACE_EVENT
/*
......@@ -287,4 +295,5 @@ static inline void tracepoint_synchronize_unregister(void)
#define TRACE_EVENT(name, proto, args, struct, assign, print) \
DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
#endif
#endif /* ifdef TRACE_EVENT (see note above) */
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