linux-kernel - Re: [PATCH -next 1/6] cpuset: add assert_cpuset_lock

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Message-ID: <c9168f74-3e24-4902-bb06-c512a5e96669@huaweicloud.com>
Date: Thu, 18 Dec 2025 08:37:59 +0800
From: Chen Ridong <chenridong@...weicloud.com>
To: Waiman Long <llong@...hat.com>, tj@...nel.org, hannes@...xchg.org,
 mkoutny@...e.com
Cc: cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
 lujialin4@...wei.com
Subject: Re: [PATCH -next 1/6] cpuset: add assert_cpuset_lock_held helper



On 2025/12/18 1:02, Waiman Long wrote:
> On 12/17/25 3:49 AM, Chen Ridong wrote:
>> From: Chen Ridong <chenridong@...wei.com>
>>
>> Add assert_cpuset_lock_held() to allow other subsystems to verify that
>> cpuset_mutex is held.
> 
> Sorry, I should have added the "lockdep_" prefix when I mentioned adding this helper function to be
> consistent with the others. Could you update the patch to add that?
> 

Thank you.

I was tangled on whether to add the lockdep_ prefix, since lockdep_assert_cpus_held has it. But I
named it as you suggested originally. I'll update the patch accordingly.

> 
>>
>> Suggested-by: Waiman Long <longman@...hat.com>
>> Signed-off-by: Chen Ridong <chenridong@...wei.com>
>> ---
>>   include/linux/cpuset.h | 2 ++
>>   kernel/cgroup/cpuset.c | 5 +++++
>>   2 files changed, 7 insertions(+)
>>
>> diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
>> index a98d3330385c..af0e76d10476 100644
>> --- a/include/linux/cpuset.h
>> +++ b/include/linux/cpuset.h
>> @@ -74,6 +74,7 @@ extern void inc_dl_tasks_cs(struct task_struct *task);
>>   extern void dec_dl_tasks_cs(struct task_struct *task);
>>   extern void cpuset_lock(void);
>>   extern void cpuset_unlock(void);
>> +extern void assert_cpuset_lock_held(void);
>>   extern void cpuset_cpus_allowed_locked(struct task_struct *p, struct cpumask *mask);
>>   extern void cpuset_cpus_allowed(struct task_struct *p, struct cpumask *mask);
>>   extern bool cpuset_cpus_allowed_fallback(struct task_struct *p);
>> @@ -195,6 +196,7 @@ static inline void inc_dl_tasks_cs(struct task_struct *task) { }
>>   static inline void dec_dl_tasks_cs(struct task_struct *task) { }
>>   static inline void cpuset_lock(void) { }
>>   static inline void cpuset_unlock(void) { }
>> +static inline void assert_cpuset_lock_held(void) { }
>>     static inline void cpuset_cpus_allowed_locked(struct task_struct *p,
>>                       struct cpumask *mask)
>> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
>> index fea577b4016a..a5ad124ea1cf 100644
>> --- a/kernel/cgroup/cpuset.c
>> +++ b/kernel/cgroup/cpuset.c
>> @@ -271,6 +271,11 @@ void cpuset_unlock(void)
>>       mutex_unlock(&cpuset_mutex);
>>   }
>>   +void assert_cpuset_lock_held(void)
>> +{
>> +    lockdep_assert_held(&cpuset_mutex);
>> +}
>> +
>>   /**
>>    * cpuset_full_lock - Acquire full protection for cpuset modification
>>    *
> 

-- 
Best regards,
Ridong