TEST SUITE:

The directory cgroup_xattr contains the tests related to extended
attributes in cgroup filesystem.

WARNING:

This test can cause a kernel panic due to a bug in kernels prior to 3.8.
It was fixed by kernel upstream commit
712317ad97f41e738e1a19aa0a6392a78a84094e:

"We should store file xattrs in struct cfent instead of struct cftype,
because cftype is a type while cfent is object instance of cftype."

TESTS AIM:

The aim of the tests is to check the extended attributes in cgroup
filesystem. This feature was added in Linux 3.7 to allow attaching runtime
meta information to cgroups and everything they model (services, apps, vms)
and can easily be shared among applications.

Test mounts as many subsystems as possible (cpu, cpuset, ...) in the
cgroup tmp directory and creates one more hierarchy. Then sets extended
attributes to all files in cgroup fs and subsequently reads the file's
extended attributes back, checking values during the process.
