Every cgroup knows all its ancestors through its ->ancestor_ids[]. While all the existing users only need the IDs, there's no advantage to remembering the IDs instead of the pointers directly. Let's replace cgroup->ancestor_ids[] with ->ancestors[] so that it's easy to access non-ID ancestor fields. This patch shouldn't cause any behavior differences. Signed-off-by: Tejun Heo <tj@xxxxxxxxxx> --- Namhyung, I think the change in bperf_cgroup is correct but couldn't figure out how to test it (normal perf build wouldn't compile it). Can you please see whether it's correct? Thanks. include/linux/cgroup-defs.h | 10 +++++----- include/linux/cgroup.h | 2 +- kernel/cgroup/cgroup.c | 7 +++---- net/netfilter/nft_socket.c | 5 +++-- tools/perf/util/bpf_skel/bperf_cgroup.bpf.c | 2 +- 5 files changed, 13 insertions(+), 13 deletions(-) diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h index 63bf43c7ca3b..51fa744c2e9d 100644 --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -379,7 +379,7 @@ struct cgroup { /* * The depth this cgroup is at. The root is at depth zero and each * step down the hierarchy increments the level. This along with - * ancestor_ids[] can determine whether a given cgroup is a + * ancestors[] can determine whether a given cgroup is a * descendant of another without traversing the hierarchy. */ int level; @@ -499,8 +499,8 @@ struct cgroup { /* Used to store internal freezer state */ struct cgroup_freezer_state freezer; - /* ids of the ancestors at each level including self */ - u64 ancestor_ids[]; + /* All ancestors including self */ + struct cgroup *ancestors[]; }; /* @@ -520,8 +520,8 @@ struct cgroup_root { /* The root cgroup. Root is destroyed on its release. */ struct cgroup cgrp; - /* for cgrp->ancestor_ids[0] */ - u64 cgrp_ancestor_id_storage; + /* for cgrp->ancestors[0] */ + u64 cgrp_ancestor_storage; /* Number of cgroups in the hierarchy, used only for /proc/cgroups */ atomic_t nr_cgrps; diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index ed53bfe7c46c..5334b6134399 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; } /** diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 85fa4c8587a8..ce587fe43dab 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -2047,7 +2047,7 @@ int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask) } root_cgrp->kn = kernfs_root_to_node(root->kf_root); WARN_ON_ONCE(cgroup_ino(root_cgrp) != 1); - root_cgrp->ancestor_ids[0] = cgroup_id(root_cgrp); + root_cgrp->ancestors[0] = root_cgrp; ret = css_populate_dir(&root_cgrp->self); if (ret) @@ -5391,8 +5391,7 @@ static struct cgroup *cgroup_create(struct cgroup *parent, const char *name, int ret; /* allocate the cgroup and its ID, 0 is reserved for the root */ - cgrp = kzalloc(struct_size(cgrp, ancestor_ids, (level + 1)), - GFP_KERNEL); + cgrp = kzalloc(struct_size(cgrp, ancestors, (level + 1)), GFP_KERNEL); if (!cgrp) return ERR_PTR(-ENOMEM); @@ -5444,7 +5443,7 @@ static struct cgroup *cgroup_create(struct cgroup *parent, const char *name, spin_lock_irq(&css_set_lock); for (tcgrp = cgrp; tcgrp; tcgrp = cgroup_parent(tcgrp)) { - cgrp->ancestor_ids[tcgrp->level] = cgroup_id(tcgrp); + cgrp->ancestors[tcgrp->level] = tcgrp; if (tcgrp != cgrp) { tcgrp->nr_descendants++; diff --git a/net/netfilter/nft_socket.c b/net/netfilter/nft_socket.c index 05ae5a338b6f..d64784d4bd02 100644 --- a/net/netfilter/nft_socket.c +++ b/net/netfilter/nft_socket.c @@ -40,6 +40,7 @@ static noinline bool nft_sock_get_eval_cgroupv2(u32 *dest, struct sock *sk, const struct nft_pktinfo *pkt, u32 level) { struct cgroup *cgrp; + u64 cgid; if (!sk_fullsock(sk)) return false; @@ -48,8 +49,8 @@ nft_sock_get_eval_cgroupv2(u32 *dest, struct sock *sk, const struct nft_pktinfo if (level > cgrp->level) return false; - memcpy(dest, &cgrp->ancestor_ids[level], sizeof(u64)); - + cgid = cgroup_id(cgrp->ancestors[level]); + memcpy(dest, &cgid, sizeof(u64)); return true; } #endif diff --git a/tools/perf/util/bpf_skel/bperf_cgroup.bpf.c b/tools/perf/util/bpf_skel/bperf_cgroup.bpf.c index 292c430768b5..bd6a420acc8f 100644 --- a/tools/perf/util/bpf_skel/bperf_cgroup.bpf.c +++ b/tools/perf/util/bpf_skel/bperf_cgroup.bpf.c @@ -68,7 +68,7 @@ static inline int get_cgroup_v1_idx(__u32 *cgrps, int size) break; // convert cgroup-id to a map index - cgrp_id = BPF_CORE_READ(cgrp, ancestor_ids[i]); + cgrp_id = BPF_CORE_READ(cgrp, ancestors[i], kn, id); elem = bpf_map_lookup_elem(&cgrp_idx, &cgrp_id); if (!elem) continue;