tracing: add protection around module events unload
When reading the trace buffer, there is a race that when a module
is unloaded it removes events that is stilled referenced in the buffers.
This patch adds the protection around the unloading of the events
from modules and the reading of the trace buffers.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 6c81f9c..aa08be6 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1050,12 +1050,13 @@
struct ftrace_event_call *call, *p;
bool found = false;
+ down_write(&trace_event_mutex);
list_for_each_entry_safe(call, p, &ftrace_events, list) {
if (call->mod == mod) {
found = true;
ftrace_event_enable_disable(call, 0);
if (call->event)
- unregister_ftrace_event(call->event);
+ __unregister_ftrace_event(call->event);
debugfs_remove_recursive(call->dir);
list_del(&call->list);
trace_destroy_fields(call);
@@ -1079,6 +1080,7 @@
*/
if (found)
tracing_reset_current_online_cpus();
+ up_write(&trace_event_mutex);
}
static int trace_module_notify(struct notifier_block *self,