[PATCH v2] tracing: Free tracer resources on instance creation failure

[Baek Kyu, Kim]

Creating a tracefs instance can allocate private tracer nodes, copied
flags and option arrays before trace_array_create_dir() returns. If a
later allocation fails, trace_array_create_systems() frees the trace_array
without releasing those private allocations. The failed instance is never
registered, so normal removal cannot reclaim them.

Free the tracer nodes and option arrays when trace_array_create_dir()
fails, then continue through the existing trace_array cleanup. Share the
option array cleanup with normal instance removal. Earlier failures still
use out_free_tr because the tracer list is not yet initialized there.

Fixes: 428add559b69 ("tracing: Have tracer option be instance specific")
Signed-off-by: Baek Kyu, Kim <pocj8ur4in@xxxxxxxxx>
---
Changes in v2:
  - Add the Fixes tag requested by Masami Hiramatsu.
  - Share option array cleanup between failed creation and normal removal.

 kernel/trace/trace.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 97a058623f94..faa90323809c 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1456,6 +1456,13 @@ static void free_tracers(struct trace_array *tr)
 	}
 }
 
+static void free_tracer_options(struct trace_array *tr)
+{
+	for (int i = 0; i < tr->nr_topts; i++)
+		kfree(tr->topts[i].topts);
+	kfree(tr->topts);
+}
+
 /**
  * register_tracer - register a tracer with the ftrace system.
  * @type: the plugin for the tracer
@@ -8751,7 +8758,7 @@ trace_array_create_systems(const char *name, const char *systems,
 	if (trace_instance_dir) {
 		ret = trace_array_create_dir(tr);
 		if (ret)
-			goto out_free_tr;
+			goto out_free_tracers;
 	} else
 		__trace_early_add_events(tr);
 
@@ -8761,6 +8768,9 @@ trace_array_create_systems(const char *name, const char *systems,
 
 	return tr;
 
+ out_free_tracers:
+	free_tracers(tr);
+	free_tracer_options(tr);
  out_free_tr:
 	ftrace_free_ftrace_ops(tr);
 	free_trace_buffers(tr);
@@ -8914,10 +8924,7 @@ static int __remove_instance(struct trace_array *tr)
 	if (tr->flags & TRACE_ARRAY_FL_VMALLOC)
 		vfree((void *)tr->range_addr_start);
 
-	for (i = 0; i < tr->nr_topts; i++) {
-		kfree(tr->topts[i].topts);
-	}
-	kfree(tr->topts);
+	free_tracer_options(tr);
 
 	free_cpumask_var(tr->pipe_cpumask);
 	free_cpumask_var(tr->tracing_cpumask);