Re: [PATCH v3 2/6] cgroup: add support for eBPF programs
flat view
From: Alexei Starovoitov <hidden>
Date: 2016-08-27 00:03:32
On Fri, Aug 26, 2016 at 09:58:48PM +0200, Daniel Mack wrote:
This patch adds two sets of eBPF program pointers to struct cgroup.
One for such that are directly pinned to a cgroup, and one for such
that are effective for it.
To illustrate the logic behind that, assume the following example
cgroup hierarchy.
A - B - C
\ D - E
If only B has a program attached, it will be effective for B, C, D
and E. If D then attaches a program itself, that will be effective for
both D and E, and the program in B will only affect B and C. Only one
program of a given type is effective for a cgroup.
Attaching and detaching programs will be done through the bpf(2)
syscall. For now, ingress and egress inet socket filtering are the
only supported use-cases.
Signed-off-by: Daniel Mack <daniel@zonque.org>...
quoted hunk ↗ jump to hunk
+ css_for_each_descendant_pre(pos, &cgrp->self) { + struct cgroup *desc = container_of(pos, struct cgroup, self); + + /* skip the subtree if the descendant has its own program */ + if (desc->bpf.prog[type] && desc != cgrp)
is desc != cgrp really needed? I thought css_for_each_descendant_pre() shouldn't walk itself or I'm missing how it works.
quoted hunk ↗ jump to hunk
+ pos = css_rightmost_descendant(pos); + else + rcu_assign_pointer(desc->bpf.effective[type], + effective); + } +} +