Re: kprobes and rcu_is_watching()

Steven Rostedt
2023-05-23T14:10:44Z

[ Added a subject, as I always want to delete these emails as spam! ]

On Mon, 22 May 2023 10:07:42 +0800
Ze Gao <zegao2021@gmail.com> wrote:

> Oops, I missed that. Thanks for pointing that out, which I thought is
> conditional use of rcu_is_watching before.
>
> One last point, I think we should double check on this
> "fentry does not filter with !rcu_is_watching"
> as quoted from Yonghong and argue whether it needs
> the same check for fentry as well.
>

Note that trace_test_and_set_recursion() (which is used by
ftrace_test_recursion_trylock()) checks for rcu_is_watching() and
returns false if it isn't (and the trylock will fail).

-- Steve