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

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Message-ID: <3ea9ec53-8bcc-4c3d-b589-7d5922daabbb@huawei.com>
Date: Fri, 26 Jul 2024 09:00:03 +0800
From: chenridong <chenridong@...wei.com>
To: Waiman Long <longman@...hat.com>, Kamalesh Babulal
	<kamalesh.babulal@...cle.com>, <tj@...nel.org>, <lizefan.x@...edance.com>,
	<hannes@...xchg.org>, <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 2024/7/26 3:07, Waiman Long wrote:
> 
> On 7/25/24 07:40, chenridong wrote:
>>
>>
>> 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);
>>>> +}
>>>> +
> 
> I would suggested a dec_attach_in_progress_locked() and a 
> dec_attach_in_progress() helpers. The dec_attach_in_progress() helper 
> acquires the cpuset_mutex and call dec_attach_in_progress_locked(). 
> Inside the dec_attach_in_progress_locked(), you can either add a comment 
> about requiring cpuset_mutex held or add a 
> lockdep_assert_held(&cpuset_mutex).
> 
> Cheers,
> Longman
> 
> 
> 
Thanks, I will do that in v2.

Ridong