tracing: Make tracing_selftest_running global to the tracing subsystem

The file trace.c has become a catchall for most things tracing. Start
making it smaller by breaking out various aspects into their own files.

Make the variable tracing_selftest_running global so that it can be used
by other files in the tracing subsystem and trace.c can be split up.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://patch.msgid.link/20260208032449.648932796@kernel.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

kernel/trace/trace.c

@@ -67,7 +67,7 @@
  * insertions into the ring-buffer such as trace_printk could occurred
  * at the same time, giving false positive or negative results.
  */
-static bool __read_mostly tracing_selftest_running;
+bool __read_mostly tracing_selftest_running;
 
 /*
  * If boot-time tracing including tracers/events via kernel cmdline
@@ -83,7 +83,6 @@ void __init disable_tracing_selftest(const char *reason)
 	}
 }
 #else
-#define tracing_selftest_running	0
 #define tracing_selftest_disabled	0
 #endif
 

kernel/trace/trace.h

@@ -863,6 +863,7 @@ extern int trace_selftest_startup_nop(struct tracer *trace,
 					 struct trace_array *tr);
 extern int trace_selftest_startup_branch(struct tracer *trace,
 					 struct trace_array *tr);
+extern bool __read_mostly tracing_selftest_running;
 /*
  * Tracer data references selftest functions that only occur
  * on boot up. These can be __init functions. Thus, when selftests
@@ -875,6 +876,7 @@ static inline void __init disable_tracing_selftest(const char *reason)
 }
 /* Tracers are seldom changed. Optimize when selftests are disabled. */
 #define __tracer_data		__read_mostly
+#define tracing_selftest_running	0
 #endif /* CONFIG_FTRACE_STARTUP_TEST */
 
 extern void *head_page(struct trace_array_cpu *data);