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Date:   Tue, 19 Nov 2019 09:13:04 -0500
From:   Steven Rostedt <rostedt@goodmis.org>
To:     Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc:     bpf <bpf@vger.kernel.org>,
        Network Development <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Ingo Molnar <mingo@kernel.org>
Subject: Re: [RFC][PATCH 1/2] ftrace: Add modify_ftrace_direct()
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On Mon, 18 Nov 2019 22:04:28 -0800
Alexei Starovoitov <alexei.starovoitov@gmail.com> wrote:

> I took your for-next without the extra patch and used it from bpf trampoline.
> It's looking good so far. Passed basic testing. Will add more stress tests.
> 
> Do you mind doing:
> diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
> index 73eb2e93593f..6ddb203ca550 100644
> --- a/include/linux/ftrace.h
> +++ b/include/linux/ftrace.h
> @@ -256,16 +256,16 @@ struct ftrace_direct_func
> *ftrace_find_direct_func(unsigned long addr);
>  # define ftrace_direct_func_count 0
>  static inline int register_ftrace_direct(unsigned long ip, unsigned long addr)
>  {
> -       return -ENODEV;
> +       return -ENOTSUPP;
>  }
>  static inline int unregister_ftrace_direct(unsigned long ip, unsigned
> long addr)
>  {
> -       return -ENODEV;
> +       return -ENOTSUPP;
>  }
>  static inline int modify_ftrace_direct(unsigned long ip,
>                                        unsigned long old_addr,
> unsigned long new_addr)
>  {
> -       return -ENODEV;
> +       return -ENOTSUPP;
>  }
> 
> otherwise ENODEV is a valid error when ip is incorrect which is
> indistinguishable from ftrace not compiled in.

Sure I can add this. Want to add a Signed-off-by to it, and I'll just
pull it in directly? I can write up the change log.

-- Steve