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authorTejun Heo <tj@kernel.org>2015-09-18 11:56:28 -0400
committerTejun Heo <tj@kernel.org>2015-09-18 11:56:28 -0400
commit49d1dc4b81797f88270832b11e9f73809e7e7209 (patch)
treeff6548a57a57834e533a4404ddabf30139060ece /kernel/cgroup.c
parentfa128fd735bd236b6b04d3fedfed7a784137c185 (diff)
downloadlinux-49d1dc4b81797f88270832b11e9f73809e7e7209.tar.bz2
cgroup: implement static_key based cgroup_subsys_enabled() and cgroup_subsys_on_dfl()
Whether a subsys is enabled and attached to the default hierarchy seldom changes and may be tested in the hot paths. This patch implements static_key based cgroup_subsys_enabled() and cgroup_subsys_on_dfl() tests. The following patches will update the users and remove duplicate mechanisms. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r--kernel/cgroup.c27
1 files changed, 26 insertions, 1 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 2cf0f79f1fc9..361938911bd1 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -139,6 +139,27 @@ static const char *cgroup_subsys_name[] = {
};
#undef SUBSYS
+/* array of static_keys for cgroup_subsys_enabled() and cgroup_subsys_on_dfl() */
+#define SUBSYS(_x) \
+ DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_enabled_key); \
+ DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_on_dfl_key); \
+ EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_enabled_key); \
+ EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_on_dfl_key);
+#include <linux/cgroup_subsys.h>
+#undef SUBSYS
+
+#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_enabled_key,
+static struct static_key_true *cgroup_subsys_enabled_key[] = {
+#include <linux/cgroup_subsys.h>
+};
+#undef SUBSYS
+
+#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_on_dfl_key,
+static struct static_key_true *cgroup_subsys_on_dfl_key[] = {
+#include <linux/cgroup_subsys.h>
+};
+#undef SUBSYS
+
/*
* The default hierarchy, reserved for the subsystems that are otherwise
* unattached - it never has more than a single cgroup, and all tasks are
@@ -1319,9 +1340,12 @@ static int rebind_subsystems(struct cgroup_root *dst_root,
/* default hierarchy doesn't enable controllers by default */
dst_root->subsys_mask |= 1 << ssid;
- if (dst_root != &cgrp_dfl_root) {
+ if (dst_root == &cgrp_dfl_root) {
+ static_branch_enable(cgroup_subsys_on_dfl_key[ssid]);
+ } else {
dst_root->cgrp.subtree_control |= 1 << ssid;
cgroup_refresh_child_subsys_mask(&dst_root->cgrp);
+ static_branch_disable(cgroup_subsys_on_dfl_key[ssid]);
}
if (ss->bind)
@@ -5483,6 +5507,7 @@ static int __init cgroup_disable(char *str)
strcmp(token, ss->legacy_name))
continue;
+ static_branch_disable(cgroup_subsys_enabled_key[i]);
ss->disabled = 1;
printk(KERN_INFO "Disabling %s control group subsystem\n",
ss->name);