Re: [PATCH -next] cgroup/cpuset: add dec_attach_in_progress helper

[chenridong]

On 2024/7/25 19:01, Kamalesh Babulal wrote:
> On 7/25/24 7:25 AM, Chen Ridong wrote:
> > There are several functions to decrease attach_in_progress, and they
> > will wake up cpuset_attach_wq when attach_in_progress is zero. So,
> > add a helper to make it concise.
> >
> > Signed-off-by: Chen Ridong <chenridong@xxxxxxxxxx>
> > ---
> >   kernel/cgroup/cpuset.c | 28 +++++++++++++++-------------
> >   1 file changed, 15 insertions(+), 13 deletions(-)
> >
> > diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> > index d4322619e59a..c241845694ac 100644
> > --- a/kernel/cgroup/cpuset.c
> > +++ b/kernel/cgroup/cpuset.c
> > @@ -490,6 +490,17 @@ static inline void check_insane_mems_config(nodemask_t *nodes)
> >   	}
> >   }
> >   
> > +/*
> > + * decrease cs->attach_in_progress.
> > + * wake_up cpuset_attach_wq if cs->attach_in_progress==0.
>
> In the description, adding locking constraint of cpuset_mutex would be helpful.
> Something like "cpuset_mutex must be held by the caller."
Thank you, I will to that.
> > + */
> > +static inline void dec_attach_in_progress(struct cpuset *cs)
> > +{
> > +	cs->attach_in_progress--;
> > +	if (!cs->attach_in_progress)
> > +		wake_up(&cpuset_attach_wq);
> > +}
> > +
> >   /*
> >    * Cgroup v2 behavior is used on the "cpus" and "mems" control files when
> >    * on default hierarchy or when the cpuset_v2_mode flag is set by mounting
> > @@ -3421,9 +3432,7 @@ static void cpuset_cancel_attach(struct cgroup_taskset *tset)
> >   	cs = css_cs(css);
> >   
> >   	mutex_lock(&cpuset_mutex);
> > -	cs->attach_in_progress--;
> > -	if (!cs->attach_in_progress)
> > -		wake_up(&cpuset_attach_wq);
> > +	dec_attach_in_progress(cs);
> >   
> >   	if (cs->nr_migrate_dl_tasks) {
> >   		int cpu = cpumask_any(cs->effective_cpus);
> > @@ -3538,9 +3547,7 @@ static void cpuset_attach(struct cgroup_taskset *tset)
> >   		reset_migrate_dl_data(cs);
> >   	}
> >   
> > -	cs->attach_in_progress--;
> > -	if (!cs->attach_in_progress)
> > -		wake_up(&cpuset_attach_wq);
> > +	dec_attach_in_progress(cs);
> >   
> >   	mutex_unlock(&cpuset_mutex);
> >   }
> > @@ -4284,9 +4291,7 @@ static void cpuset_cancel_fork(struct task_struct *task, struct css_set *cset)
> >   		return;
> >   
> >   	mutex_lock(&cpuset_mutex);
> > -	cs->attach_in_progress--;
> > -	if (!cs->attach_in_progress)
> > -		wake_up(&cpuset_attach_wq);
> > +	dec_attach_in_progress(cs);
> >   	mutex_unlock(&cpuset_mutex);
> >   }
> >   
> > @@ -4319,10 +4324,7 @@ static void cpuset_fork(struct task_struct *task)
> >   	guarantee_online_mems(cs, &cpuset_attach_nodemask_to);
> >   	cpuset_attach_task(cs, task);
> >   
> > -	cs->attach_in_progress--;
> > -	if (!cs->attach_in_progress)
> > -		wake_up(&cpuset_attach_wq);
> > -
> > +	dec_attach_in_progress(cs);
> >   	mutex_unlock(&cpuset_mutex);
> >   }
> >