[PATCH RESEND] tracing/osnoise: Dump stack on timerlat uret threshold event

[PATCH RESEND] tracing/osnoise: Dump stack on timerlat uret threshold event

[Crystal Wood]

Dump the saved IRQ stack trace regardless of whether the event was
THREAD_CONTEXT or THREAD_URET.

In the uret case, the latency presumably had not yet crossed the
threshold at IRQ time (or else it would have dumped the stack at thread
wakeup time, unless we're racing with a change to the threshold), but it
may have at least contributed -- and this is possible with THREAD_CONTEXT
as well.

In any case, it helps with writing reliable rtla tests if we always get
a stack trace on a threshold event.

Signed-off-by: Crystal Wood <crwood@redhat.com>
---
Original: https://lore.kernel.org/all/20251112152529.956778-3-crwood@redhat.com/

 kernel/trace/trace_osnoise.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
index 75678053b21c..62c2667d97fa 100644
--- a/kernel/trace/trace_osnoise.c
+++ b/kernel/trace/trace_osnoise.c
@@ -2544,9 +2544,12 @@ timerlat_fd_read(struct file *file, char __user *ubuf, size_t count,
 		notify_new_max_latency(diff);
 
 		tlat->tracing_thread = false;
-		if (osnoise_data.stop_tracing_total)
-			if (time_to_us(diff) >= osnoise_data.stop_tracing_total)
+		if (osnoise_data.stop_tracing_total) {
+			if (time_to_us(diff) >= osnoise_data.stop_tracing_total) {
+				timerlat_dump_stack(time_to_us(diff));
 				osnoise_stop_tracing();
+			}
+		}
 	} else {
 		tlat->tracing_thread = false;
 		tlat->kthread = current;
-- 
2.54.0