tracing/osnoise: Fix build when timerlat is not enabled

To fix some critical section races, the interface_lock was added to a few
locations. One of those locations was above where the interface_lock was
declared, so the declaration was moved up before that usage.
Unfortunately, where it was placed was inside a CONFIG_TIMERLAT_TRACER
ifdef block. As the interface_lock is used outside that config, this broke
the build when CONFIG_OSNOISE_TRACER was enabled but
CONFIG_TIMERLAT_TRACER was not.

Cc: Masami Hiramatsu <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: "Helena Anna" <[email protected]>
Cc: "Luis Claudio R. Goncalves" <[email protected]>
Cc: Tomas Glozar <[email protected]>
Link: https://lore.kernel.org/[email protected]
Fixes: e6a5348 ("tracing/timerlat: Only clear timer if a kthread exists")
Reported-by: "Bityutskiy, Artem" <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

Author: rostedt

kernel/trace/trace_osnoise.c

@@ -228,6 +228,11 @@ static inline struct osnoise_variables *this_cpu_osn_var(void)
 	return this_cpu_ptr(&per_cpu_osnoise_var);
 }
 
+/*
+ * Protect the interface.
+ */
+static struct mutex interface_lock;
+
 #ifdef CONFIG_TIMERLAT_TRACER
 /*
  * Runtime information for the timer mode.
@@ -252,11 +257,6 @@ static inline struct timerlat_variables *this_cpu_tmr_var(void)
 	return this_cpu_ptr(&per_cpu_timerlat_var);
 }
 
-/*
- * Protect the interface.
- */
-static struct mutex interface_lock;
-
 /*
  * tlat_var_reset - Reset the values of the given timerlat_variables
  */