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Date: Tue, 23 May 2023 10:10:41 -0400
From: Steven Rostedt <rostedt@goodmis.org>
To: Ze Gao <zegao2021@gmail.com>
Cc: Jiri Olsa <olsajiri@gmail.com>, Yonghong Song <yhs@meta.com>, Alexei
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Subject: Re: kprobes and rcu_is_watching()
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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