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

[Waiman Long]

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.

Cheers,
Longman