Messages in this thread | | | Date | Tue, 9 Nov 2021 11:02:37 -0500 | From | Steven Rostedt <> | Subject | Re: [PATCH] ftrace/direct: Fix lockup in modify_ftrace_direct_multi |
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On Tue, 9 Nov 2021 12:42:17 +0100 Jiri Olsa <jolsa@redhat.com> wrote:
> We can't call unregister_ftrace_function under ftrace_lock.
Ouch.
Do you have a sample module that triggers this?
I thought we had something that tested this code, but I don't see it in my tree.
-- Steve
> > Fixes: ed29271894aa ("ftrace/direct: Do not disable when switching direct callers") > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > --- > kernel/trace/ftrace.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index b4ed1a301232..fc49e8809a56 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -5602,10 +5602,11 @@ int modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr) > } > } > > + mutex_unlock(&ftrace_lock); > + > /* Removing the tmp_ops will add the updated direct callers to the functions */ > unregister_ftrace_function(&tmp_ops); > > - mutex_unlock(&ftrace_lock); > out_direct: > mutex_unlock(&direct_mutex); > return err;
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