Introduce netcls_mutex to synchronize modifications to
cgroup_cls_state. New cgrp now inherits classid from ->css_online()
and write_classid() updates classid while holdin netcls_mutex.
As write_classid() doesn't propagate new configuration downwards, this
currently doesn't make any userland-visible difference, but will help
implementing proper hierarchy support.
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
---
net/sched/cls_cgroup.c | 21 ++++++++++++++++++---
1 file changed, 18 insertions(+), 3 deletions(-)
diff --git a/net/sched/cls_cgroup.c b/net/sched/cls_cgroup.c
index 8cdc18e..80a80c4 100644
--- a/net/sched/cls_cgroup.c
+++ b/net/sched/cls_cgroup.c
@@ -17,11 +17,14 @@
#include <linux/skbuff.h>
#include <linux/cgroup.h>
#include <linux/rcupdate.h>
+#include <linux/mutex.h>
#include <net/rtnetlink.h>
#include <net/pkt_cls.h>
#include <net/sock.h>
#include <net/cls_cgroup.h>
+static DEFINE_MUTEX(netcls_mutex);
+
static inline struct cgroup_cls_state *cgrp_cls_state(struct cgroup *cgrp)
{
return container_of(cgroup_subsys_state(cgrp, net_cls_subsys_id),
@@ -42,12 +45,21 @@ static struct cgroup_subsys_state *cgrp_css_alloc(struct cgroup *cgrp)
if (!cs)
return ERR_PTR(-ENOMEM);
- if (cgrp->parent)
- cs->classid = cgrp_cls_state(cgrp->parent)->classid;
-
return &cs->css;
}
+/* @cgrp coming online, inherit the parent's classid */
+static int cgrp_css_online(struct cgroup *cgrp)
+{
+ if (!cgrp->parent)
+ return 0;
+
+ mutex_lock(&netcls_mutex);
+ cgrp_cls_state(cgrp)->classid = cgrp_cls_state(cgrp->parent)->classid;
+ mutex_unlock(&netcls_mutex);
+ return 0;
+}
+
static void cgrp_css_free(struct cgroup *cgrp)
{
kfree(cgrp_cls_state(cgrp));
@@ -60,7 +72,9 @@ static u64 read_classid(struct cgroup *cgrp, struct cftype *cft)
static int write_classid(struct cgroup *cgrp, struct cftype *cft, u64 value)
{
+ mutex_lock(&netcls_mutex);
cgrp_cls_state(cgrp)->classid = (u32) value;
+ mutex_unlock(&netcls_mutex);
return 0;
}
@@ -76,6 +90,7 @@ static struct cftype ss_files[] = {
struct cgroup_subsys net_cls_subsys = {
.name = "net_cls",
.css_alloc = cgrp_css_alloc,
+ .css_online = cgrp_css_online,
.css_free = cgrp_css_free,
.subsys_id = net_cls_subsys_id,
.base_cftypes = ss_files,
--
1.7.11.7
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