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    SubjectRe: [PATCH 1/2] ftrace: disable preemption on the testing of recursion
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    On 2021/10/12 下午8:17, Steven Rostedt wrote:
    > On Tue, 12 Oct 2021 13:40:08 +0800
    > 王贇 <yun.wang@linux.alibaba.com> wrote:
    >
    >> @@ -52,11 +52,6 @@ static void notrace klp_ftrace_handler(unsigned long ip,
    >> bit = ftrace_test_recursion_trylock(ip, parent_ip);
    >> if (WARN_ON_ONCE(bit < 0))
    >> return;
    >> - /*
    >> - * A variant of synchronize_rcu() is used to allow patching functions
    >> - * where RCU is not watching, see klp_synchronize_transition().
    >> - */
    >
    > I have to take a deeper look at this patch set, but do not remove this
    > comment, as it explains the protection here, that is not obvious with the
    > changes you made.

    Will keep that in v2.

    Regards,
    Michael Wang

    >
    > -- Steve
    >
    >
    >> - preempt_disable_notrace();
    >>
    >> func = list_first_or_null_rcu(&ops->func_stack, struct klp_func,
    >> stack_node);

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