linux-kernel - Re: [PATCH -next] cgroup/cpuset: add dec_attach_in

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Message-ID: <de6958aa-27f8-4baa-b76d-88266d009f81@huawei.com>
Date: Thu, 25 Jul 2024 19:40:15 +0800
From: chenridong <chenridong@...wei.com>
To: Kamalesh Babulal <kamalesh.babulal@...cle.com>, <tj@...nel.org>,
	<lizefan.x@...edance.com>, <hannes@...xchg.org>, <longman@...hat.com>,
	<adityakali@...gle.com>, <sergeh@...nel.org>, <mkoutny@...e.com>
CC: <cgroups@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH -next] cgroup/cpuset: add dec_attach_in_progress helper



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@...wei.com>
>> ---
>>   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);
>>   }
>>   
>