Re: [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@xxxxxxxxxx>
> > ---
> >   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