linux-kernel - Re: [paulmck-rcu:dev.2024.06.18a 20/34] kernel/time/clocksource.c:136:25: error: 'CONFIG_CLOCKSOURCE_WATCHDOG_MAX_SKEW

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Date: Wed, 19 Jun 2024 22:03:32 -0700
From: "Paul E. McKenney" <paulmck@...nel.org>
To: kernel test robot <lkp@...el.com>
Cc: oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [paulmck-rcu:dev.2024.06.18a 20/34]
 kernel/time/clocksource.c:136:25: error:
 'CONFIG_CLOCKSOURCE_WATCHDOG_MAX_SKEW_US' undeclared

On Thu, Jun 20, 2024 at 11:16:36AM +0800, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2024.06.18a
> head:   f29bcafffef0ecc8a5d2cdc1bbef9a6889225263
> commit: 5800c05045dbfeb8c9e571c6b47e8d7dd0d0691d [20/34] clocksource: Take advantage of always-defined CLOCKSOURCE_WATCHDOG_MAX_SKEW_US
> config: arc-randconfig-002-20240620 (https://download.01.org/0day-ci/archive/20240620/202406201116.d69O9imA-lkp@intel.com/config)
> compiler: arc-elf-gcc (GCC) 13.2.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240620/202406201116.d69O9imA-lkp@intel.com/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@...el.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202406201116.d69O9imA-lkp@intel.com/
> 
> All errors (new ones prefixed by >>):
> 
>    kernel/time/clocksource.c: In function '__clocksource_update_freq_scale':
> >> kernel/time/clocksource.c:136:25: error: 'CONFIG_CLOCKSOURCE_WATCHDOG_MAX_SKEW_US' undeclared (first use in this function)
>      136 | #define MAX_SKEW_USEC   CONFIG_CLOCKSOURCE_WATCHDOG_MAX_SKEW_US
>          |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>    kernel/time/clocksource.c:137:28: note: in expansion of macro 'MAX_SKEW_USEC'
>      137 | #define WATCHDOG_MAX_SKEW (MAX_SKEW_USEC * NSEC_PER_USEC)
>          |                            ^~~~~~~~~~~~~
>    kernel/time/clocksource.c:1167:50: note: in expansion of macro 'WATCHDOG_MAX_SKEW'
>     1167 |                 if (cs->uncertainty_margin < 2 * WATCHDOG_MAX_SKEW)
>          |                                                  ^~~~~~~~~~~~~~~~~
>    kernel/time/clocksource.c:136:25: note: each undeclared identifier is reported only once for each function it appears in
>      136 | #define MAX_SKEW_USEC   CONFIG_CLOCKSOURCE_WATCHDOG_MAX_SKEW_US
>          |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>    kernel/time/clocksource.c:137:28: note: in expansion of macro 'MAX_SKEW_USEC'
>      137 | #define WATCHDOG_MAX_SKEW (MAX_SKEW_USEC * NSEC_PER_USEC)
>          |                            ^~~~~~~~~~~~~
>    kernel/time/clocksource.c:1167:50: note: in expansion of macro 'WATCHDOG_MAX_SKEW'
>     1167 |                 if (cs->uncertainty_margin < 2 * WATCHDOG_MAX_SKEW)
>          |                                                  ^~~~~~~~~~~~~~~~~
> 

I have dropped this patch, and thank you for your testing!

								Thanx, Paul

> vim +/CONFIG_CLOCKSOURCE_WATCHDOG_MAX_SKEW_US +136 kernel/time/clocksource.c
> 
> 2e27e793e280ff1 Paul E. McKenney 2021-05-27  119  
> 2e27e793e280ff1 Paul E. McKenney 2021-05-27  120  /*
> 2e27e793e280ff1 Paul E. McKenney 2021-05-27  121   * Maximum permissible delay between two readouts of the watchdog
> 2e27e793e280ff1 Paul E. McKenney 2021-05-27  122   * clocksource surrounding a read of the clocksource being validated.
> 2e27e793e280ff1 Paul E. McKenney 2021-05-27  123   * This delay could be due to SMIs, NMIs, or to VCPU preemptions.  Used as
> 2e27e793e280ff1 Paul E. McKenney 2021-05-27  124   * a lower bound for cs->uncertainty_margin values when registering clocks.
> c37e85c135cead4 Paul E. McKenney 2022-12-06  125   *
> c37e85c135cead4 Paul E. McKenney 2022-12-06  126   * The default of 500 parts per million is based on NTP's limits.
> c37e85c135cead4 Paul E. McKenney 2022-12-06  127   * If a clocksource is good enough for NTP, it is good enough for us!
> ababe5f6bfbf3eb Borislav Petkov  2024-06-12  128   *
> ababe5f6bfbf3eb Borislav Petkov  2024-06-12  129   * In other words, by default, even if a clocksource is extremely
> ababe5f6bfbf3eb Borislav Petkov  2024-06-12  130   * precise (for example, with a sub-nanosecond period), the maximum
> ababe5f6bfbf3eb Borislav Petkov  2024-06-12  131   * permissible skew between the clocksource watchdog and the clocksource
> ababe5f6bfbf3eb Borislav Petkov  2024-06-12  132   * under test is not permitted to go below the 500ppm minimum defined
> ababe5f6bfbf3eb Borislav Petkov  2024-06-12  133   * by MAX_SKEW_USEC.  This 500ppm minimum may be overridden using the
> ababe5f6bfbf3eb Borislav Petkov  2024-06-12  134   * CLOCKSOURCE_WATCHDOG_MAX_SKEW_US Kconfig option.
> 2e27e793e280ff1 Paul E. McKenney 2021-05-27  135   */
> fc153c1c58cb8c3 Waiman Long      2021-12-05 @136  #define MAX_SKEW_USEC	CONFIG_CLOCKSOURCE_WATCHDOG_MAX_SKEW_US
> fc153c1c58cb8c3 Waiman Long      2021-12-05  137  #define WATCHDOG_MAX_SKEW (MAX_SKEW_USEC * NSEC_PER_USEC)
> 2e27e793e280ff1 Paul E. McKenney 2021-05-27  138  
> 
> :::::: The code at line 136 was first introduced by commit
> :::::: fc153c1c58cb8c3bb3b443b4d7dc3211ff5f65fc clocksource: Add a Kconfig option for WATCHDOG_MAX_SKEW
> 
> :::::: TO: Waiman Long <longman@...hat.com>
> :::::: CC: Paul E. McKenney <paulmck@...nel.org>
> 
> -- 
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki