tracing: tprobe-events: Fix to clean up tprobe correctly when module unload

When unloading module, the tprobe events are not correctly cleaned
up. Thus it becomes `fprobe-event` and never be enabled again even
if loading the same module again.

For example;

 # cd /sys/kernel/tracing
 # modprobe trace_events_sample
 # echo 't:my_tprobe foo_bar' >> dynamic_events
 # cat dynamic_events
t:tracepoints/my_tprobe foo_bar
 # rmmod trace_events_sample
 # cat dynamic_events
f:tracepoints/my_tprobe foo_bar

As you can see, the second time my_tprobe starts with 'f' instead
of 't'.

This unregisters the fprobe and tracepoint callback when module is
unloaded but marks the fprobe-event is tprobe-event.

Link: https://lore.kernel.org/all/174158724946.189309.15826571379395619524.stgit@mhiramat.tok.corp.google.com/
Fixes: 57a7e6de9e30 ("tracing/fprobe: Support raw tracepoints on future loaded modules")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c
index e27305d31fc57c167fd2ab62a8eb5bb34ae59bd8..88a80953ae5ea54a285c61d51db9b3bd979855cd 100644 (file)
--- a/kernel/trace/trace_fprobe.c
+++ b/kernel/trace/trace_fprobe.c
@@ -1008,10 +1008,13 @@ static int __tracepoint_probe_module_cb(struct notifier_block *self,
                                        reenable_trace_fprobe(tf);
                        }
                } else if (val == MODULE_STATE_GOING && tp_mod->mod == tf->mod) {
-                       tracepoint_probe_unregister(tf->tpoint,
+                       unregister_fprobe(&tf->fp);
+                       if (trace_fprobe_is_tracepoint(tf)) {
+                               tracepoint_probe_unregister(tf->tpoint,
                                        tf->tpoint->probestub, NULL);
-                       tf->tpoint = NULL;
-                       tf->mod = NULL;
+                               tf->tpoint = TRACEPOINT_STUB;
+                               tf->mod = NULL;
+                       }
                }
        }
        mutex_unlock(&event_mutex);