On Mon, Jan 13, 2014 at 09:01:49AM +0100, Jan Kaluza wrote:

Server-like processes in many cases need credentials and other
metadata of the peer, to decide if the calling process is allowed to
request a specific action, or the server just wants to log away this
type of information for auditing tasks.

The current practice to retrieve such process metadata is to look that
information up in procfs with the $PID received over SCM_CREDENTIALS.
This is sufficient for long-running tasks, but introduces a race which
cannot be worked around for short-living processes; the calling
process and all the information in /proc/$PID/ is gone before the
receiver of the socket message can look it up.

This introduces a new SCM type called SCM_CGROUP to allow the direct
attaching of "cgroup_path" to SCM, which is significantly more
efficient and will reliably avoid the race with the round-trip over
procfs.

Signed-off-by: Jan Kaluza <redacted>

For cgroup related part:

 Acked-by: Tejun Heo [off-list ref]

Thanks.

-- 
tejun