On Thu, 2013-05-16 at 20:48 +0900, Masami Hiramatsu wrote:
> 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 under removing module at that time.
>
Thanks, this looks to be something that needs to go in right away.
-- Steve
> Signed-off-by: Masami Hiramatsu <masami.hiramatsu...@hitachi.com>
> Cc: Steven Rostedt <rost...@goodmis.org>
> Cc: Frederic Weisbecker <fweis...@gmail.com>
> Cc: Ingo Molnar <mi...@redhat.com>
> ---
> 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 7a0cf68..27963e2 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)
--
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