cpuset: remove redundant CS_ONLINE flag

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The CS_ONLINE flag was introduced prior to the CSS_ONLINE flag in the
cpuset subsystem. Currently, the flag setting sequence is as follows:

1. cpuset_css_online() sets CS_ONLINE
2. css->flags gets CSS_ONLINE set
...
3. cgroup->kill_css sets CSS_DYING
4. cpuset_css_offline() clears CS_ONLINE
5. css->flags clears CSS_ONLINE

The is_cpuset_online() check currently occurs between steps 1 and 3.
However, it would be equally safe to perform this check between steps 2
and 3, as CSS_ONLINE provides the same synchronization guarantee as
CS_ONLINE.

Since CS_ONLINE is redundant with CSS_ONLINE and provides no additional
synchronization benefits, we can safely remove it to simplify the code.

Signed-off-by: Chen Ridong <chenridong@huawei.com>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

...

This commit is contained in:

Chen Ridong 2025-08-13 08:29:01 +00:00 • committed by Tejun Heo

parent 8a013ec9cb

commit 4c70fb2624

3 changed files with 7 additions and 5 deletions

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5

include/linux/cgroup.h

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3

kernel/cgroup/cpuset-internal.h

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4

kernel/cgroup/cpuset.c

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