On Thu, Sep 05, 2024 at 01:41:28PM GMT, Chen Ridong <chenridong@xxxxxxxxxx> wrote:
> Whether a cgroup is frozen is determined solely by whether it is set to
> to be frozen and whether its parent is frozen. Currently, when is cgroup
> is frozen or unfrozen, it iterates through the entire subtree to freeze
> or unfreeze its descentdants.
It's more to maintain the numeric freeze "layers".
> However, this is unesessary for a cgroup that does not change its
> effective frozen status.
True.
> +static inline void cgroup_update_efreeze(struct cgroup *cgrp)
> +{
> + struct cgroup *parent = cgroup_parent(cgrp);
> + bool p_e = false;
> +
> + if (parent)
> + p_e = parent->freezer.e_freeze;
> +
> + cgrp->freezer.e_freeze = cgrp->freezer.freeze | p_e;
Better be || on bools
I'd open code this inside the loop of cgroup_freeze since it is not
context-less function and it relies on top-down processing.
Root cgrp cannot be frozen. You can bail out early in the beginning of
cgroup_freeze() (possibly with a WARN_ON) and then assume parent is
always valid when iterating.
I think maintaining the e_freeze in this "saturated arithmetic" form is
a sensible change.
Thanks,
Michal
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