[PATCH 7/7] netprio_cgroup: allow nesting and inherit config on cgroup creation

Tejun Heo
2012-11-20T08:30:44Z

Inherit netprio configuration from ->css_online(), allow nesting and
remove .broken_hierarchy marking. This makes netprio_cgroup's
behavior match netcls_cgroup's.

Note that this patch changes userland-visible behavior. Nesting is
allowed and the first level cgroups below the root cgroup behave
differently - they inherit priorities from the root cgroup on creation
instead of starting with 0. This is unfortunate but not doing so is
much crazier.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
Documentation/cgroups/net_prio.txt | 2 ++
net/core/netprio_cgroup.c | 42 ++++++++++++++++++++++----------------
2 files changed, 26 insertions(+), 18 deletions(-)

diff --git a/Documentation/cgroups/net_prio.txt b/Documentation/cgroups/net_prio.txt
index 01b3226..a82cbd2 100644
--- a/Documentation/cgroups/net_prio.txt
+++ b/Documentation/cgroups/net_prio.txt
@@ -51,3 +51,5 @@ One usage for the net_prio cgroup is with mqprio qdisc allowing application
traffic to be steered to hardware/driver based traffic classes. These mappings
can then be managed by administrators or other networking protocols such as
DCBX.
+
+A new net_prio cgroup inherits the parent's configuration.
diff --git a/net/core/netprio_cgroup.c b/net/core/netprio_cgroup.c
index b2af0d0..bde53da 100644
--- a/net/core/netprio_cgroup.c
+++ b/net/core/netprio_cgroup.c
@@ -136,9 +136,6 @@ static struct cgroup_subsys_state *cgrp_css_alloc(struct cgroup *cgrp)
{
struct cgroup_netprio_state *cs;

- if (cgrp->parent && cgrp->parent->id)
- return ERR_PTR(-EINVAL);
-
cs = kzalloc(sizeof(*cs), GFP_KERNEL);
if (!cs)
return ERR_PTR(-ENOMEM);
@@ -146,16 +143,34 @@ static struct cgroup_subsys_state *cgrp_css_alloc(struct cgroup *cgrp)
return &cs->css;
}

-static void cgrp_css_free(struct cgroup *cgrp)
+static int cgrp_css_online(struct cgroup *cgrp)
{
- struct cgroup_netprio_state *cs = cgrp_netprio_state(cgrp);
+ struct cgroup *parent = cgrp->parent;
struct net_device *dev;
+ int ret = 0;
+
+ if (!parent)
+ return 0;

rtnl_lock();
- for_each_netdev(&init_net, dev)
- WARN_ON_ONCE(netprio_set_prio(cgrp, dev, 0));
+ /*
+ * Inherit prios from the parent. As all prios are set during
+ * onlining, there is no need to clear them on offline.
+ */
+ for_each_netdev(&init_net, dev) {
+ u32 prio = netprio_prio(parent, dev);
+
+ ret = netprio_set_prio(cgrp, dev, prio);
+ if (ret)
+ break;
+ }
rtnl_unlock();
- kfree(cs);
+ return ret;
+}
+
+static void cgrp_css_free(struct cgroup *cgrp)
+{
+ kfree(cgrp_netprio_state(cgrp));
}

static u64 read_prioidx(struct cgroup *cgrp, struct cftype *cft)
@@ -237,21 +252,12 @@ static struct cftype ss_files[] = {
struct cgroup_subsys net_prio_subsys = {
.name = "net_prio",
.css_alloc = cgrp_css_alloc,
+ .css_online = cgrp_css_online,
.css_free = cgrp_css_free,
.attach = net_prio_attach,
.subsys_id = net_prio_subsys_id,
.base_cftypes = ss_files,
.module = THIS_MODULE,
-
- /*
- * net_prio has artificial limit on the number of cgroups and
- * disallows nesting making it impossible to co-mount it with other
- * hierarchical subsystems. Remove the artificially low PRIOIDX_SZ
- * limit and properly nest configuration such that children follow
- * their parents' configurations by default and are allowed to
- * override and remove the following.
- */
- .broken_hierarchy = true,
};

static int netprio_device_event(struct notifier_block *unused,
--
1.7.11.7