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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 Starovoitov <ast@kernel.org>,
        Andrii Nakryiko <andrii@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Hao Luo <haoluo@google.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>,
        Martin KaFai Lau <martin.lau@linux.dev>,
        Masami Hiramatsu <mhiramat@kernel.org>,
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        Ze Gao <zegao@tencent.com>
Subject: Re: kprobes and rcu_is_watching()
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[ 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