From 6ed0106667d76589cb648c27edb4f4ffbf9d59ca Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Thu, 16 May 2013 20:48:49 +0900 Subject: [PATCH] tracing: Return -EBUSY when event_enable_func() fails to get module Since try_module_get() returns false( = 0) when it fails to pindown a module, event_enable_func() returns 0 which means "succeed". This can cause a kernel panic when the entry is removed, because the event is already released. This fixes the bug by returning -EBUSY, because the reason why it fails is that the module is being removed at that time. Link: http://lkml.kernel.org/r/20130516114848.13508.97899.stgit@mhiramat-M0-7522 Cc: Srikar Dronamraju Cc: Oleg Nesterov Cc: Tom Zanussi Cc: Frederic Weisbecker Cc: Ingo Molnar Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt --- kernel/trace/trace_events.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 7a0cf68027cc..27963e2bf4bf 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -2072,8 +2072,10 @@ event_enable_func(struct ftrace_hash *hash, out_reg: /* Don't let event modules unload while probe registered */ ret = try_module_get(file->event_call->mod); - if (!ret) + if (!ret) { + ret = -EBUSY; goto out_free; + } ret = __ftrace_event_enable_disable(file, 1, 1); if (ret < 0)