[PATCH 12/33] cpuset: Provide lockdep check for cpuset lock held

[Waiman Long]

On 1/11/26 8:43 PM, Waiman Long wrote:
> On 1/1/26 5:13 PM, Frederic Weisbecker wrote:
>> cpuset modifies partitions, including isolated, while holding the cpuset
>> mutex.
>>
>> This means that holding the cpuset mutex is safe to synchronize against
>> housekeeping cpumask changes.
>>
>> Provide a lockdep check to validate that.
>>
>> Signed-off-by: Frederic Weisbecker <frederic at kernel.org>
>> ---
>>   include/linux/cpuset.h | 2 ++
>>   kernel/cgroup/cpuset.c | 7 +++++++
>>   2 files changed, 9 insertions(+)
>>
>> diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
>> index a98d3330385c..1c49ffd2ca9b 100644
>> --- a/include/linux/cpuset.h
>> +++ b/include/linux/cpuset.h
>> @@ -18,6 +18,8 @@
>>   #include <linux/mmu_context.h>
>>   #include <linux/jump_label.h>
>>   +extern bool lockdep_is_cpuset_held(void);
>> +
>>   #ifdef CONFIG_CPUSETS
>>     /*
>> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
>> index 3afa72f8d579..5e2e3514c22e 100644
>> --- a/kernel/cgroup/cpuset.c
>> +++ b/kernel/cgroup/cpuset.c
>> @@ -283,6 +283,13 @@ void cpuset_full_unlock(void)
>>       cpus_read_unlock();
>>   }
>>   +#ifdef CONFIG_LOCKDEP
>> +bool lockdep_is_cpuset_held(void)
>> +{
>> +    return lockdep_is_held(&cpuset_mutex);
>> +}
>> +#endif
>> +
>>   static DEFINE_SPINLOCK(callback_lock);
>>     void cpuset_callback_lock_irq(void)
>
> The cgroup/for-next tree already have a similar 
> lockdep_assert_cpuset_lock_held() defined. So you can drop this patch 
> if this series won't land in the next merge window. 

Sorry, the other new lockdep API isn't exactly the same as what you 
propose here. So it is not a replacement for your use case. Sorry for 
the noise.

Cheers,
Longman