[PATCH 6/7] netprio_cgroup: implement netprio[_set]_prio() helpers

Tejun Heo
2012-11-20T07:06:55Z

Introduce two helpers - netprio_prio() and netprio_set_prio() - which
hide the details of priomap access and expansion. This will help
implementing hierarchy support.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
---
net/core/netprio_cgroup.c | 72 ++++++++++++++++++++++++++++++++---------------
1 file changed, 50 insertions(+), 22 deletions(-)

diff --git a/net/core/netprio_cgroup.c b/net/core/netprio_cgroup.c
index 9409cdf..b2af0d0 100644
--- a/net/core/netprio_cgroup.c
+++ b/net/core/netprio_cgroup.c
@@ -87,6 +87,51 @@ static int extend_netdev_table(struct net_device *dev, u32 target_idx)
return 0;
}

+/**
+ * netprio_prio - return the effective netprio of a cgroup-net_device pair
+ * @cgrp: cgroup part of the target pair
+ * @dev: net_device part of the target pair
+ *
+ * Should be called under RCU read or rtnl lock.
+ */
+static u32 netprio_prio(struct cgroup *cgrp, struct net_device *dev)
+{
+ struct netprio_map *map = rcu_dereference_rtnl(dev->priomap);
+
+ if (map && cgrp->id < map->priomap_len)
+ return map->priomap[cgrp->id];
+ return 0;
+}
+
+/**
+ * netprio_set_prio - set netprio on a cgroup-net_device pair
+ * @cgrp: cgroup part of the target pair
+ * @dev: net_device part of the target pair
+ * @prio: prio to set
+ *
+ * Set netprio to @prio on @cgrp-@dev pair. Should be called under rtnl
+ * lock and may fail under memory pressure for non-zero @prio.
+ */
+static int netprio_set_prio(struct cgroup *cgrp, struct net_device *dev,
+ u32 prio)
+{
+ struct netprio_map *map;
+ int ret;
+
+ /* avoid extending priomap for zero writes */
+ map = rtnl_dereference(dev->priomap);
+ if (!prio && (!map || map->priomap_len <= cgrp->id))
+ return 0;
+
+ ret = extend_netdev_table(dev, cgrp->id);
+ if (ret)
+ return ret;
+
+ map = rtnl_dereference(dev->priomap);
+ map->priomap[cgrp->id] = prio;
+ return 0;
+}
+
static struct cgroup_subsys_state *cgrp_css_alloc(struct cgroup *cgrp)
{
struct cgroup_netprio_state *cs;
@@ -105,14 +150,10 @@ static void cgrp_css_free(struct cgroup *cgrp)
{
struct cgroup_netprio_state *cs = cgrp_netprio_state(cgrp);
struct net_device *dev;
- struct netprio_map *map;

rtnl_lock();
- for_each_netdev(&init_net, dev) {
- map = rtnl_dereference(dev->priomap);
- if (map && cgrp->id < map->priomap_len)
- map->priomap[cgrp->id] = 0;
- }
+ for_each_netdev(&init_net, dev)
+ WARN_ON_ONCE(netprio_set_prio(cgrp, dev, 0));
rtnl_unlock();
kfree(cs);
}
@@ -126,16 +167,10 @@ static int read_priomap(struct cgroup *cont, struct cftype *cft,
struct cgroup_map_cb *cb)
{
struct net_device *dev;
- u32 id = cont->id;
- u32 priority;
- struct netprio_map *map;

rcu_read_lock();
- for_each_netdev_rcu(&init_net, dev) {
- map = rcu_dereference(dev->priomap);
- priority = (map && id < map->priomap_len) ? map->priomap[id] : 0;
- cb->fill(cb, dev->name, priority);
- }
+ for_each_netdev_rcu(&init_net, dev)
+ cb->fill(cb, dev->name, netprio_prio(cont, dev));
rcu_read_unlock();
return 0;
}
@@ -145,7 +180,6 @@ static int write_priomap(struct cgroup *cgrp, struct cftype *cft,
{
char devname[IFNAMSIZ + 1];
struct net_device *dev;
- struct netprio_map *map;
u32 prio;
int ret;

@@ -158,14 +192,8 @@ static int write_priomap(struct cgroup *cgrp, struct cftype *cft,

rtnl_lock();

- ret = extend_netdev_table(dev, cgrp->id);
- if (ret)
- goto out_unlock;
+ ret = netprio_set_prio(cgrp, dev, prio);

- map = rtnl_dereference(dev->priomap);
- if (map)
- map->priomap[cgrp->id] = prio;
-out_unlock:
rtnl_unlock();
dev_put(dev);
return ret;
--
1.7.11.7