rtla/timerlat_hist: Abort event processing on second signal

If either SIGINT is received twice, or after a SIGALRM (that is, after
timerlat was supposed to stop), abort processing events currently left
in the tracefs buffer and exit immediately.

This allows the user to exit rtla without waiting for processing all
events, should that take longer than wanted, at the cost of not
processing all samples.

Cc: John Kacur <[email protected]>
Cc: Luis Goncalves <[email protected]>
Cc: Gabriele Monaco <[email protected]>
Link: https://lore.kernel.org/[email protected]
Signed-off-by: Tomas Glozar <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

Author: lenticularis39

tools/tracing/rtla/src/timerlat_hist.c

@@ -1134,6 +1134,14 @@ static int stop_tracing;
 static struct trace_instance *hist_inst = NULL;
 static void stop_hist(int sig)
 {
+	if (stop_tracing) {
+		/*
+		 * Stop requested twice in a row; abort event processing and
+		 * exit immediately
+		 */
+		tracefs_iterate_stop(hist_inst->inst);
+		return;
+	}
 	stop_tracing = 1;
 	if (hist_inst)
 		trace_instance_stop(hist_inst);