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

JIRA: https://issues.redhat.com/browse/RHEL-86682

commit 0a8bb68
Author: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Date:   Mon Mar 10 15:14:09 2025 +0900

    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: 57a7e6d ("tracing/fprobe: Support raw tracepoints on future loaded modules")
    Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Signed-off-by: Jerome Marchand <jmarchan@redhat.com>

Author: jeromemarchand

kernel/trace/trace_fprobe.c

@@ -977,10 +977,13 @@ 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);