linux-kernel - Re: [PATCH -next v5 3/3] cpuset: add helpers for cpus read and cpuset

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Message-ID: <312f3e07-0eb9-4bdf-b5bd-24c84ef5fcc1@redhat.com>
Date: Tue, 26 Aug 2025 10:43:35 -0400
From: Waiman Long <llong@...hat.com>
To: Michal Koutný <mkoutny@...e.com>,
 Chen Ridong <chenridong@...weicloud.com>
Cc: tj@...nel.org, hannes@...xchg.org, cgroups@...r.kernel.org,
 linux-kernel@...r.kernel.org, lujialin4@...wei.com, chenridong@...wei.com
Subject: Re: [PATCH -next v5 3/3] cpuset: add helpers for cpus read and
 cpuset_mutex locks


On 8/26/25 10:23 AM, Michal Koutný wrote:
> (I wrote this yesterday before merging but I'm still sending it to give
> my opinion ;-))
>
> On Mon, Aug 25, 2025 at 03:23:52AM +0000, Chen Ridong <chenridong@...weicloud.com> wrote:
>> From: Chen Ridong <chenridong@...wei.com>
>>
>> cpuset: add helpers for cpus_read_lock and cpuset_mutex locks.
>>
>> Replace repetitive locking patterns with new helpers:
>> - cpuset_full_lock()
>> - cpuset_full_unlock()
> I don't see many precedents elsewhere in the kernel for such naming
> (like _lock and _full_lock()). Wouldn't it be more illustrative to have
> cpuset_read_lock() and cpuset_write_lock()? (As I'm looking at current
> users and your accompanying comments which could be substituted with
> the more conventional naming.)
Good naming is always an issue. Using cpuset_read_lock/cpuset_write_lock 
will be more confusing as the current locking scheme is exclusive.
> (Also if you decide going this direction, please mention commit
> 111cd11bbc548 ("sched/cpuset: Bring back cpuset_mutex") in the message
> so that it doesn't tempt to do further changes.)
>
>
>> This makes the code cleaner and ensures consistent lock ordering.
> Lock guards anyone? (When you're touching this and seeking clean code.)

Yes, I guess we can use lock guards here. You are welcome to send a 
patch to do that.

Cheers,
Longman


>
> Thanks,
> Michal