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authorTejun Heo <tj@kernel.org>2022-07-29 13:10:16 -1000
committerTejun Heo <tj@kernel.org>2022-08-15 11:16:47 -1000
commit7f203bc89eb66d6afde7eae91347fc0352090cc3 (patch)
treea8a4f1fa1203a0200089982587709f334b0ff968 /include/linux/cgroup.h
parent568035b01cfb107af8d2e4bd2fb9aea22cf5b868 (diff)
cgroup: Replace cgroup->ancestor_ids[] with ->ancestors[]
Every cgroup knows all its ancestors through its ->ancestor_ids[]. There's no advantage to remembering the IDs instead of the pointers directly and this makes the array useless for finding an actual ancestor cgroup forcing cgroup_ancestor() to iteratively walk up the hierarchy instead. Let's replace cgroup->ancestor_ids[] with ->ancestors[] and remove the walking-up from cgroup_ancestor(). While at it, improve comments around cgroup_root->cgrp_ancestor_storage. This patch shouldn't cause user-visible behavior differences. v2: Update cgroup_ancestor() to use ->ancestors[]. v3: cgroup_root->cgrp_ancestor_storage's type is updated to match cgroup->ancestors[]. Better comments. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Namhyung Kim <namhyung@kernel.org>
Diffstat (limited to 'include/linux/cgroup.h')
-rw-r--r--include/linux/cgroup.h8
1 files changed, 3 insertions, 5 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index ed53bfe7c46c..4d143729b246 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -574,7 +574,7 @@ static inline bool cgroup_is_descendant(struct cgroup *cgrp,
{
if (cgrp->root != ancestor->root || cgrp->level < ancestor->level)
return false;
- return cgrp->ancestor_ids[ancestor->level] == cgroup_id(ancestor);
+ return cgrp->ancestors[ancestor->level] == ancestor;
}
/**
@@ -591,11 +591,9 @@ static inline bool cgroup_is_descendant(struct cgroup *cgrp,
static inline struct cgroup *cgroup_ancestor(struct cgroup *cgrp,
int ancestor_level)
{
- if (cgrp->level < ancestor_level)
+ if (ancestor_level < 0 || ancestor_level > cgrp->level)
return NULL;
- while (cgrp && cgrp->level > ancestor_level)
- cgrp = cgroup_parent(cgrp);
- return cgrp;
+ return cgrp->ancestors[ancestor_level];
}
/**