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SubjectRe: [PATCH v2] locking/rwsem: Add DEBUG_RWSEMS to look for lock/unlock mismatches
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On 03/27/2018 02:06 AM, Ingo Molnar wrote:
> * Waiman Long <longman@redhat.com> wrote:
>
>> For a rwsem, locking can either be exclusive or shared. The corresponding
>> exclusive or shared unlock must be used. Otherwise, the protected data
>> structures may get corrupted or the lock may be in an inconsistent state.
>>
>> In order to detect such anomaly, a new configuration option DEBUG_RWSEMS
>> is added which can be enabled to look for such mismatches and print
>> warnings that that happens.
>> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
>> index 64155e3..0958192 100644
>> --- a/lib/Kconfig.debug
>> +++ b/lib/Kconfig.debug
>> @@ -1075,6 +1075,13 @@ config DEBUG_WW_MUTEX_SLOWPATH
>> even a debug kernel. If you are a driver writer, enable it. If
>> you are a distro, do not.
>>
>> +config DEBUG_RWSEMS
>> + bool "RW Semaphore debugging: basic checks"
>> + depends on DEBUG_KERNEL && RWSEM_SPIN_ON_OWNER
>> + help
>> + This feature allows mismatched rw semaphore locks and unlocks
>> + to be detected and reported.
>> +
> Makes sense - but this should also be integrated into the rest of lock debugging
> Kconfig hierarchy similar to DEBUG_MUTEXES: i.e. DEBUG_LOCK_ALLOC, PROVE_LOCKING,
> etc. should select this new lock debugging option as well.
>
> People generally are not supposed to know and configure the finer details,
> CONFIG_LOCK_DEBUGGING=y is a one-stop-shop in this regard.

I can add a patch to rework lock debugging configuration code. Do you
want to hide the individual config options but still allow them to be
enabled manually? Alternatively we can also just add a master lock
debugging option to select them all.

Cheers,
Longman



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