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

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Message-ID: <198cec94-6d2c-46c0-a46a-9ab810deb7e0@redhat.com>
Date: Wed, 17 Dec 2025 12:02:55 -0500
From: Waiman Long <llong@...hat.com>
To: Chen Ridong <chenridong@...weicloud.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 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?

Thanks,
Longman

>
> 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
>    *