[PATCH bpf-next v5 1/5] cgroup: Add bpf prog revisions to struct cgroup_bpf

[Yonghong Song <yonghong.song@linux.dev>]

One of key items in mprog API is revision for prog list. The revision
number will be increased if the prog list changed, e.g., attach, detach
or replace.

Add 'revisions' field to struct cgroup_bpf, representing revisions for
all cgroup related attachment types. The initial revision value is
set to 1, the same as kernel mprog implementations.

Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
---
 include/linux/bpf-cgroup-defs.h | 1 +
 kernel/cgroup/cgroup.c          | 5 +++++
 2 files changed, 6 insertions(+)

diff --git a/include/linux/bpf-cgroup-defs.h b/include/linux/bpf-cgroup-defs.h
index 0985221d5478..c9e6b26abab6 100644
--- a/include/linux/bpf-cgroup-defs.h
+++ b/include/linux/bpf-cgroup-defs.h
@@ -63,6 +63,7 @@ struct cgroup_bpf {
 	 */
 	struct hlist_head progs[MAX_CGROUP_BPF_ATTACH_TYPE];
 	u8 flags[MAX_CGROUP_BPF_ATTACH_TYPE];
+	u64 revisions[MAX_CGROUP_BPF_ATTACH_TYPE];
 
 	/* list of cgroup shared storages */
 	struct list_head storages;
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index a723b7dc6e4e..312c6a8b55bb 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -2074,6 +2074,11 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp)
 	for_each_subsys(ss, ssid)
 		INIT_LIST_HEAD(&cgrp->e_csets[ssid]);
 
+#ifdef CONFIG_CGROUP_BPF
+	for (int i = 0; i < ARRAY_SIZE(cgrp->bpf.revisions); i++)
+		cgrp->bpf.revisions[i] = 1;
+#endif
+
 	init_waitqueue_head(&cgrp->offline_waitq);
 	INIT_WORK(&cgrp->release_agent_work, cgroup1_release_agent);
 }
-- 
2.47.1