From 32c33e822cb5539b286ec71895e3669228fe706a Mon Sep 17 00:00:00 2001
From: Tomas Glozar <tglozar@redhat.com>
Date: Thu, 16 Jan 2025 15:49:29 +0100
Subject: [PATCH] rtla/timerlat_top: Stop timerlat tracer on signal
commit a4dfce7559d75430c464294ddee554be2a413c4a upstream.
Currently, when either SIGINT from the user or SIGALRM from the duration
timer is caught by rtla-timerlat, stop_tracing is set to break out of
the main loop. This is not sufficient for cases where the timerlat
tracer is producing more data than rtla can consume, since in that case,
rtla is looping indefinitely inside tracefs_iterate_raw_events, never
reaches the check of stop_tracing and hangs.
In addition to setting stop_tracing, also stop the timerlat tracer on
received signal (SIGINT or SIGALRM). This will stop new samples so that
the existing samples may be processed and tracefs_iterate_raw_events
eventually exits.
Cc: stable@vger.kernel.org
Cc: John Kacur <jkacur@redhat.com>
Cc: Luis Goncalves <lgoncalv@redhat.com>
Cc: Gabriele Monaco <gmonaco@redhat.com>
Link: https://lore.kernel.org/20250116144931.649593-4-tglozar@redhat.com
Fixes: a828cd18bc4a ("rtla: Add timerlat tool and timelart top mode")
Signed-off-by: Tomas Glozar <tglozar@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
tools/tracing/rtla/src/timerlat_top.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/tools/tracing/rtla/src/timerlat_top.c b/tools/tracing/rtla/src/timerlat_top.c
index 8fc0f6aa19dad..08e940ecdc966 100644
--- a/tools/tracing/rtla/src/timerlat_top.c
+++ b/tools/tracing/rtla/src/timerlat_top.c
@@ -575,9 +575,12 @@ static struct osnoise_tool
}
static int stop_tracing;
+static struct trace_instance *top_inst = NULL;
static void stop_top(int sig)
{
stop_tracing = 1;
+ if (top_inst)
+ trace_instance_stop(top_inst);
}
/*
@@ -620,6 +623,13 @@ int timerlat_top_main(int argc, char *argv[])
}
trace = &top->trace;
+ /*
+ * Save trace instance into global variable so that SIGINT can stop
+ * the timerlat tracer.
+ * Otherwise, rtla could loop indefinitely when overloaded.
+ */
+ top_inst = trace;
+
retval = enable_timerlat(trace);
if (retval) {
@@ -690,7 +700,7 @@ int timerlat_top_main(int argc, char *argv[])
return_value = 0;
- if (trace_is_off(&top->trace, &record->trace)) {
+ if (trace_is_off(&top->trace, &record->trace) && !stop_tracing) {
printf("rtla timerlat hit stop tracing\n");
if (params->trace_output) {
printf(" Saving trace to %s\n", params->trace_output);
--
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