Re: [gpio kself-test & bisect] gpio-mockup.sh kslef-test failed in v6.3-rc5

[Pengfei Xu <pengfei.xu@xxxxxxxxx>]

Hi Andy,

On 2023-04-06 at 13:26:36 +0300, Andy Shevchenko wrote:
> On Thu, Apr 6, 2023 at 12:15 PM Pengfei Xu <pengfei.xu@xxxxxxxxx> wrote:
> >
> > Hi Christophe Leroy and gpio experts,
> >
> > Greeting!
> >
> > Platform: Tigerlake-H and so on x86 platforms
> >
> > All detailed info is in link: https://github.com/xupengfe/syzkaller_logs/tree/main/issue_bisect/230406_gpio-mockup_kselftest_failed_bisect_v63rc5
> > Bisect info: https://github.com/xupengfe/syzkaller_logs/blob/main/issue_bisect/230406_gpio-mockup_kselftest_failed_bisect_v63rc5/bisect_info.txt
> >
> > gpio-mockup.sh kslef-test failed in v6.3-rc5 kernel.
> > gpio-mockup.sh(gpio overflow test) in kself-test could reproduce this issue:
> > cd linux/tools/testing/selftests
> >  1.  ./kselftest_install.sh
> >  2.  cd  linux/tools/testing/selftests/kselftest_install/gpio
> >  # ./gpio-mockup.sh
> >  1.  Module load tests
> >  1.1.  dynamic allocation of gpio
> >  2.  Module load error tests
> >  2.1 gpio overflow
> >  test failed: unexpected chip - gpiochip1
> >  GPIO gpio-mockup test FAIL
> >
> > And the simplified steps to reproduce this issue are as follow:
> > "
> > # Load gpio_mockup with overflow ranges -1,1024:
> > modprobe -q gpio_mockup gpio_mockup_ranges="-1,1024"
> >
> > # Check is there some Call Trace generated in dmesg
> > dmesg | grep -C 5 Call
> >
> > # Should not generate any gpiochip folder like /sys/kernel/debug/gpio-mockup/gpiochip1
> > # Because load gpio_mockup with overflow ranges -1,1024
> > find "/sys/kernel/debug/gpio-mockup/" -name gpiochip* -type d | sort
> >
> > # Unload the gpio_mockup module
> > modprobe -r gpio_mockup
> > # Check is there "Call Trace" generated in dmesg
> > dmesg | grep -C 5 Call
> > "
> >
> > Actually the judgement "gpio-mockup.sh" test/bisect judgement point is that:
> > Should not generate any gpiochip folder like
> > /sys/kernel/debug/gpio-mockup/gpiochip1 after load gpio_mockup with overflow
> > ranges -1,1024.
> >
> > I met gpio-mockup.sh test failed but there is no any "Call Trace" dmesg info
> > sometimes.
> >
> > So the shortest check steps are as follow:
> > "
> > 1. modprobe -q gpio_mockup gpio_mockup_ranges="-1,1024"
> > After above gpio_mockup module loaded with overflow range "-1,1024":
> > Correct behavior as previous v6.1 or older kernel:"gpio should not load "gpiochip1" due to overflow range -1,1024";
> > Wrong behavior in v6.3-rc5 kernel: "gpio *load* "gpiochip1" with overflow range -1,1024 and "gpiochip1" should not be loaded".
> > The underlying problem was already buried here.
> >
> > 2. Could use below command to check if "gpiochip1" generated:
> > As before v6.1,  there was no "/sys/kernel/debug/gpio-mockup/gpiochip1" sysfs folder due to overflow range -1,1024";
> > Wrong behavior in v6.3-rc5 kernel: "/sys/kernel/debug/gpio-mockup/gpiochip1" sysfs folder generated as follow command check:
> > # find "/sys/kernel/debug/gpio-mockup/" -name gpiochip* -type d | sort
> > /sys/kernel/debug/gpio-mockup/gpiochip1
> > If there is gpiochip* generated, gpio-mockup.sh kself-test would be failed also.
> > "
> >
> > Bisected and found the bad commit was:
> > "
> > 7b61212f2a07a5afd213c8876e52b5c9946441e2
> > gpiolib: Get rid of ARCH_NR_GPIOS
> > "
> > And after reverted the above commit on top of v6.3-rc5 kernel, above
> > gpio-mockup.sh kself-test could pass and this issue was gone.
> >
> > Now gpio-mockup.sh kself-test is failed on almost all x86 platform from
> > v6.2 cycle mainline kernel.
> >
> > I hope above info is helpful to solve the "gpio-mockup.sh kself-test failed"
> > problem.
> 
> Thank you for the report and full analysis of the root cause. I think
> we may fix the test script however the gpio-mockup is obsoleted and
> should be actually replaced with tests again gpio-sim.
> 
  Thanks for your info! So we should ignore the gpio-mockup module related
  test next time and the gpio-mockup kself-test is not necessary.
  My colleague "Lai Yi" also found this issue.
https://lore.kernel.org/lkml/ZCvusEIauvO8BLM5@xxxxxxxxxxxxxxxx/

  If there is a patch update please add:
  "Reported-by: Pengfei Xu <pengfei.xu@xxxxxxxxx>
   Reported-by: Yi Lai <yi1.lai@xxxxxxxxx>
  "

  Thanks!
  BR.
  -Pengfei
> -- 
> With Best Regards,
> Andy Shevchenko