bpf: extend bpf_prog_array to store pointers to the cgroup storage

This patch converts bpf_prog_array from an array of prog pointers
to the array of struct bpf_prog_array_item elements.

This allows to save a cgroup storage pointer for each bpf program
efficiently attached to a cgroup.

Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

drivers/media/rc/bpf-lirc.c

@@ -195,14 +195,16 @@ void lirc_bpf_run(struct rc_dev *rcdev, u32 sample)
  */
 void lirc_bpf_free(struct rc_dev *rcdev)
 {
-	struct bpf_prog **progs;
+	struct bpf_prog_array_item *item;
 
 	if (!rcdev->raw->progs)
 		return;
 
-	progs = rcu_dereference(rcdev->raw->progs)->progs;
-	while (*progs)
-		bpf_prog_put(*progs++);
+	item = rcu_dereference(rcdev->raw->progs)->items;
+	while (item->prog) {
+		bpf_prog_put(item->prog);
+		item++;
+	}
 
 	bpf_prog_array_free(rcdev->raw->progs);
 }