[v3] selftests/ftrace: Do not trace do_softirq because of PREEMPT_RT

Commit Message

Krzysztof Kozlowski Feb. 14, 2022, 8:36 a.m. UTC

The PREEMPT_RT patchset does not use do_softirq() function thus trying
to filter for do_softirq fails for such kernel:

  echo do_softirq
  ftracetest: 81: echo: echo: I/O error

Choose some other visible function for the test.  The function does not
have to be actually executed during the test, because it is only testing
filter API interface.

Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Reviewed-by: Shuah Khan <[e-mail]>
Reviewed-by: Steven Rostedt (VMware) <[e-mail]>

---

Changes since v2:
1. Rephrase commit msg, after comments from Sebastian.
2. Add review tag.

Changes since v1:
1. Use scheduler_tick.
2. Add review tag.

Notes:
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(-)

Comments

Sebastian Andrzej Siewior Feb. 14, 2022, 11:19 a.m. UTC | #1

On 2022-02-14 09:36:57 [+0100], Krzysztof Kozlowski wrote:
> The PREEMPT_RT patchset does not use do_softirq() function thus trying
> to filter for do_softirq fails for such kernel:
> 
>   echo do_softirq
>   ftracetest: 81: echo: echo: I/O error
> 
> Choose some other visible function for the test.  The function does not
> have to be actually executed during the test, because it is only testing
> filter API interface.
> 
> Signed-off-by: Krzysztof Kozlowski <[e-mail]>
> Reviewed-by: Shuah Khan <[e-mail]>
> Reviewed-by: Steven Rostedt (VMware) <[e-mail]>

Acked-by: Sebastian Andrzej Siewior <[e-mail]>

> Notes:
> I understand that the failure does not exist on mainline kernel (only
> with PREEMPT_RT patchset) but the change does not harm it.

Yes, and now it does not sound (to me) like duct tape. Thank you.

> If it is not suitable alone, please consider it for RT patchset.

We trying to get it merged so…

Sebastian

Shuah Khan Feb. 14, 2022, 6:33 p.m. UTC | #2

On 2/14/22 4:19 AM, Sebastian Andrzej Siewior wrote:
> On 2022-02-14 09:36:57 [+0100], Krzysztof Kozlowski wrote:
>> The PREEMPT_RT patchset does not use do_softirq() function thus trying
>> to filter for do_softirq fails for such kernel:
>>
>>    echo do_softirq
>>    ftracetest: 81: echo: echo: I/O error
>>
>> Choose some other visible function for the test.  The function does not
>> have to be actually executed during the test, because it is only testing
>> filter API interface.
>>
>> Signed-off-by: Krzysztof Kozlowski <[e-mail]>
>> Reviewed-by: Shuah Khan <[e-mail]>
>> Reviewed-by: Steven Rostedt (VMware) <[e-mail]>
> 
> Acked-by: Sebastian Andrzej Siewior <[e-mail]>
> 
>> Notes:
>> I understand that the failure does not exist on mainline kernel (only
>> with PREEMPT_RT patchset) but the change does not harm it.
> 

Steve,

Would you like me to take this through linux-kselftest next for 5.18-rc1

I am guessing there is no urgency on this - of not I can take this in for
rc5.

thanks,
-- Shuah

Steven Rostedt Feb. 14, 2022, 6:39 p.m. UTC | #3

On Mon, 14 Feb 2022 11:33:18 -0700
Shuah Khan <[e-mail]> wrote:

> Steve,
> 
> Would you like me to take this through linux-kselftest next for 5.18-rc1
> 
> I am guessing there is no urgency on this - of not I can take this in for
> rc5.

Hi Shuah,

Feel free to take it through your tree in any urgent level you like.

Reviewed-by: Steven Rostedt (Google) <[e-mail]>

-- Steve

Patch

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..25432b8cd5bd 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="scheduler_tick"
 
 ALL_FUNCS="#### all functions enabled ####"