From b854ac0024db08361c361249bdd1cc5f82719c27 Mon Sep 17 00:00:00 2001 From: Tomas Glozar Date: Thu, 16 Jan 2025 15:49:28 +0100 Subject: [PATCH] rtla/timerlat_hist: Stop timerlat tracer on signal commit c73cab9dbed04d8f65ca69177b4b21ed3e09dfa7 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 Cc: Luis Goncalves Cc: Gabriele Monaco Link: https://lore.kernel.org/20250116144931.649593-3-tglozar@redhat.com Fixes: 1eeb6328e8b3 ("rtla/timerlat: Add timerlat hist mode") Signed-off-by: Tomas Glozar Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman --- tools/tracing/rtla/src/timerlat_hist.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/tools/tracing/rtla/src/timerlat_hist.c b/tools/tracing/rtla/src/timerlat_hist.c index ed08295bfa12..83cc7ef3d36b 100644 --- a/tools/tracing/rtla/src/timerlat_hist.c +++ b/tools/tracing/rtla/src/timerlat_hist.c @@ -783,9 +783,12 @@ out_err: } static int stop_tracing; +static struct trace_instance *hist_inst = NULL; static void stop_hist(int sig) { stop_tracing = 1; + if (hist_inst) + trace_instance_stop(hist_inst); } /* @@ -828,6 +831,12 @@ int timerlat_hist_main(int argc, char *argv[]) } trace = &tool->trace; + /* + * Save trace instance into global variable so that SIGINT can stop + * the timerlat tracer. + * Otherwise, rtla could loop indefinitely when overloaded. + */ + hist_inst = trace; retval = enable_timerlat(trace); if (retval) { @@ -894,7 +903,7 @@ int timerlat_hist_main(int argc, char *argv[]) return_value = 0; - if (trace_is_off(&tool->trace, &record->trace)) { + if (trace_is_off(&tool->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);