Messages in this thread | | | Date | Tue, 9 Nov 2021 19:04:59 +0100 | From | Jiri Olsa <> | Subject | Re: [PATCH] ftrace/direct: Fix lockup in modify_ftrace_direct_multi |
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On Tue, Nov 09, 2021 at 11:02:37AM -0500, Steven Rostedt wrote: > 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.
I triggered that with my bpf batch changes
there's not test for modify at the moment, just register/unregister I'll add one
jirka
> > -- 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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