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Subject: Re: [PATCH] selftests/ftrace: Do not trace do_softirq because of
 PREEMPT_RT
To:     Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>, Shuah Khan <shuah@kernel.org>,
        linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-rt-users@vger.kernel.org, joseph.salisbury@canonical.com,
        Shuah Khan <skhan@linuxfoundation.org>
References: <20220209162430.286578-1-krzysztof.kozlowski@canonical.com>
From:   Shuah Khan <skhan@linuxfoundation.org>
Message-ID: <aa0833ac-154e-9a66-c3f5-7c3b98f15f19@linuxfoundation.org>
Date:   Wed, 9 Feb 2022 12:26:40 -0700
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On 2/9/22 9:24 AM, Krzysztof Kozlowski wrote:
> The PREEMPT_RT patchset does not use soft IRQs thus trying to filter for
> do_softirq fails for such kernel:
> 
>    echo do_softirq
>    ftracetest: 81: echo: echo: I/O error
> 
> Choose some other externally visible function for the test.
> 
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
> 
> ---
> 
> I understand that the failure does not exist on mainline kernel (only
> with PREEMPT_RT patchset) but the change does not harm it.
> 
> If it is not suitable alone, please consider it for RT patchset.
> ---
>   .../selftests/ftrace/test.d/ftrace/func_set_ftrace_file.tc      | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/ftrace/test.d/ftrace/func_set_ftrace_file.tc b/tools/testing/selftests/ftrace/test.d/ftrace/func_set_ftrace_file.tc
> index e96e279e0533..1d0c7601865f 100644
> --- a/tools/testing/selftests/ftrace/test.d/ftrace/func_set_ftrace_file.tc
> +++ b/tools/testing/selftests/ftrace/test.d/ftrace/func_set_ftrace_file.tc
> @@ -19,7 +19,7 @@ fail() { # mesg
>   
>   FILTER=set_ftrace_filter
>   FUNC1="schedule"
> -FUNC2="do_softirq"
> +FUNC2="_printk"
>   
>   ALL_FUNCS="#### all functions enabled ####"
>   
> 

Change looks good to me.

Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>

thanks,
-- Shuah