From: Tomas Glozar tglozar@redhat.com

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 --- 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 059b468981e4..d21a21053917 100644 --- a/tools/tracing/rtla/src/timerlat_top.c +++ b/tools/tracing/rtla/src/timerlat_top.c @@ -900,9 +900,12 @@ 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); }

/* @@ -950,6 +953,13 @@ 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) { @@ -1131,7 +1141,7 @@ 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->no_aa)