+Device controller
+-----------------
+
+Device controller manages access to device files. It includes both
+creation of new device files (using mknod), and access to the
+existing device files.
+
+Cgroup v2 device controller has no interface files and is implemented
+on top of cgroup BPF. To control access to device files, a user may
+create bpf programs of the BPF_CGROUP_DEVICE type and attach them
+to cgroups. On an attempt to access a device file, corresponding
+BPF programs will be executed, and depending on the return value
+the attempt will succeed or fail with -EPERM.
+
+A BPF_CGROUP_DEVICE program takes a pointer to the bpf_cgroup_dev_ctx
+structure, which describes the device access attempt: access type
+(mknod/read/write) and device (type, major and minor numbers).
+If the program returns 0, the attempt fails with -EPERM, otherwise
+it succeeds.
+
+An example of BPF_CGROUP_DEVICE program may be found in the kernel
+source tree in the tools/testing/selftests/bpf/dev_cgroup.c file.
+
+