bpf/cgroup: Replace rcu_swap_protected() with rcu_replace_pointer()

This commit replaces the use of rcu_swap_protected() with the more
intuitively appealing rcu_replace_pointer() as a step towards removing
rcu_swap_protected().

Link: https://lore.kernel.org/lkml/CAHk-=wiAsJLw1egFEE=Z7-GGtM6wcvtyytXZA1+BHqta4gg6Hw@mail.gmail.com/
Reported-by: Linus Torvalds <[email protected]>
[ paulmck: From rcu_replace() to rcu_replace_pointer() per Ingo Molnar. ]
Signed-off-by: Paul E. McKenney <[email protected]>
Acked-by: Andrii Nakryiko <[email protected]>
Acked-by: Song Liu <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Daniel Borkmann <[email protected]>
Cc: Martin KaFai Lau <[email protected]>
Cc: Yonghong Song <[email protected]>
Cc: <[email protected]>
Cc: <[email protected]>

Author: paulmckrcu

kernel/bpf/cgroup.c

@@ -180,8 +180,8 @@ static void activate_effective_progs(struct cgroup *cgrp,
 				     enum bpf_attach_type type,
 				     struct bpf_prog_array *old_array)
 {
-	rcu_swap_protected(cgrp->bpf.effective[type], old_array,
-			   lockdep_is_held(&cgroup_mutex));
+	old_array = rcu_replace_pointer(cgrp->bpf.effective[type], old_array,
+					lockdep_is_held(&cgroup_mutex));
 	/* free prog array after grace period, since __cgroup_bpf_run_*()
 	 * might be still walking the array
 	 */