[PATCH 4.14 04/43] tracing: Dump stacktrace trigger to the corresponding instance

[Greg Kroah-Hartman]

From: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>

commit ce33c845b030c9cf768370c951bc699470b09fa7 upstream.

The stacktrace event trigger is not dumping the stacktrace to the instance
where it was enabled, but to the global "instance."

Use the private_data, pointing to the trigger file, to figure out the
corresponding trace instance, and use it in the trigger action, like
snapshot_trigger does.

Link: https://lkml.kernel.org/r/afbb0b4f18ba92c276865bc97204d438473f4ebc.1645396236.git.bristot@xxxxxxxxxx

Cc: stable@xxxxxxxxxxxxxxx
Fixes: ae63b31e4d0e2 ("tracing: Separate out trace events from global variables")
Reviewed-by: Tom Zanussi <zanussi@xxxxxxxxxx>
Tested-by: Tom Zanussi <zanussi@xxxxxxxxxx>
Signed-off-by: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 kernel/trace/trace_events_trigger.c |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -1196,7 +1196,14 @@ static __init int register_trigger_snaps
 static void
 stacktrace_trigger(struct event_trigger_data *data, void *rec)
 {
-	trace_dump_stack(STACK_SKIP);
+	struct trace_event_file *file = data->private_data;
+	unsigned long flags;
+
+	if (file) {
+		local_save_flags(flags);
+		__trace_stack(file->tr, flags, STACK_SKIP, preempt_count());
+	} else
+		trace_dump_stack(STACK_SKIP);
 }
 
 static void