Re: [PATCH bpf-next v4 3/4] bpf: cgroup: properly use bpf_prog_array api

On Tue, May 28, 2019 at 02:14:43PM -0700, Stanislav Fomichev wrote:

Now that we don't have __rcu markers on the bpf_prog_array helpers,
let's use proper rcu_dereference_protected to obtain array pointer
under mutex.

We also don't need __rcu annotations on cgroup_bpf.inactive since
it's not read/updated concurrently.

v4:
* drop cgroup_rcu_xyz wrappers and use rcu APIs directly; presumably
  should be more clear to understand which mutex/refcount protects
  each particular place

v3:
* amend cgroup_rcu_dereference to include percpu_ref_is_dying;
  cgroup_bpf is now reference counted and we don't hold cgroup_mutex
  anymore in cgroup_bpf_release

v2:
* replace xchg with rcu_swap_protected

Cc: Roman Gushchin <redacted>
Signed-off-by: Stanislav Fomichev <redacted>

Yeah, the looks even better.

Acked-by: Roman Gushchin <redacted>

Thanks!