rtla: Fix double free

Avoid double free by making trace_instance_destroy indempotent.  When
trace_instance_init fails, it calls trace_instance_destroy, but its only
caller osnoise_destroy_tool calls it again.

Link: https://lkml.kernel.org/r/mvmilnlkyzx.fsf_-_@suse.de

Fixes: 0605bf0 ("rtla: Add osnoise tool")
Signed-off-by: Andreas Schwab <schwab@suse.de>
Acked-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Author: andreas-schwab

tools/tracing/rtla/src/trace.c

@@ -134,13 +134,18 @@ void trace_instance_destroy(struct trace_instance *trace)
 	if (trace->inst) {
 		disable_tracer(trace->inst);
 		destroy_instance(trace->inst);
+		trace->inst = NULL;
 	}
 
-	if (trace->seq)
+	if (trace->seq) {
 		free(trace->seq);
+		trace->seq = NULL;
+	}
 
-	if (trace->tep)
+	if (trace->tep) {
 		tep_free(trace->tep);
+		trace->tep = NULL;
+	}
 }
 
 /*