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authorTejun Heo <tj@kernel.org>2014-07-15 11:05:10 -0400
committerTejun Heo <tj@kernel.org>2014-07-15 11:05:10 -0400
commita8ddc8215e1a4cd9dc5d6210811cfc381a489ec2 (patch)
tree647056238f18f982969e1aad6d2f564e99d99d65 /kernel
parent2cf669a58dc08fa065a8bd0dca866c0e6cb358cc (diff)
cgroup: distinguish the default and legacy hierarchies when handling cftypes
Until now, cftype arrays carried files for both the default and legacy hierarchies and the files which needed to be used on only one of them were flagged with either CFTYPE_ONLY_ON_DFL or CFTYPE_INSANE. This gets confusing very quickly and we may end up exposing interface files to the default hierarchy without thinking it through. This patch makes cgroup core provide separate sets of interfaces for cftype handling so that the cftypes for the default and legacy hierarchies are clearly distinguished. The previous two patches renamed the existing ones so that they clearly indicate that they're for the legacy hierarchies. This patch adds the interface for the default hierarchy and apply them selectively depending on the hierarchy type. * cftypes added through cgroup_subsys->dfl_cftypes and cgroup_add_dfl_cftypes() only show up on the default hierarchy. * cftypes added through cgroup_subsys->legacy_cftypes and cgroup_add_legacy_cftypes() only show up on the legacy hierarchies. * cgroup_subsys->dfl_cftypes and ->legacy_cftypes can point to the same array for the cases where the interface files are identical on both types of hierarchies. * This makes all the existing subsystem interface files legacy-only by default and all subsystems will have no interface file created when enabled on the default hierarchy. Each subsystem should explicitly review and compose the interface for the default hierarchy. * A boot param "cgroup__DEVEL__legacy_files_on_dfl" is added which makes subsystems which haven't decided the interface files for the default hierarchy to present the legacy files on the default hierarchy so that its behavior on the default hierarchy can be tested. As the awkward name suggests, this is for development only. * memcg's CFTYPE_INSANE on "use_hierarchy" is noop now as the whole array isn't used on the default hierarchy. The flag is removed. v2: Updated documentation for cgroup__DEVEL__legacy_files_on_dfl. v3: Clear CFTYPE_ONLY_ON_DFL and CFTYPE_INSANE when cfts are removed as suggested by Li. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Aristeu Rozanski <aris@redhat.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cgroup.c62
1 files changed, 59 insertions, 3 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index c275aa439a6f..374ebdf74f35 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -149,6 +149,12 @@ struct cgroup_root cgrp_dfl_root;
*/
static bool cgrp_dfl_root_visible;
+/*
+ * Set by the boot param of the same name and makes subsystems with NULL
+ * ->dfl_files to use ->legacy_files on the default hierarchy.
+ */
+static bool cgroup_legacy_files_on_dfl;
+
/* some controllers are not supported in the default hierarchy */
static const unsigned int cgrp_dfl_root_inhibit_ss_mask = 0
#ifdef CONFIG_CGROUP_DEBUG
@@ -3085,6 +3091,9 @@ static void cgroup_exit_cftypes(struct cftype *cfts)
kfree(cft->kf_ops);
cft->kf_ops = NULL;
cft->ss = NULL;
+
+ /* revert flags set by cgroup core while adding @cfts */
+ cft->flags &= ~(CFTYPE_ONLY_ON_DFL | CFTYPE_INSANE);
}
}
@@ -3195,8 +3204,37 @@ static int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
return ret;
}
+/**
+ * cgroup_add_dfl_cftypes - add an array of cftypes for default hierarchy
+ * @ss: target cgroup subsystem
+ * @cfts: zero-length name terminated array of cftypes
+ *
+ * Similar to cgroup_add_cftypes() but the added files are only used for
+ * the default hierarchy.
+ */
+int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
+{
+ struct cftype *cft;
+
+ for (cft = cfts; cft && cft->name[0] != '\0'; cft++)
+ cft->flags |= CFTYPE_ONLY_ON_DFL;
+ return cgroup_add_cftypes(ss, cfts);
+}
+
+/**
+ * cgroup_add_legacy_cftypes - add an array of cftypes for legacy hierarchies
+ * @ss: target cgroup subsystem
+ * @cfts: zero-length name terminated array of cftypes
+ *
+ * Similar to cgroup_add_cftypes() but the added files are only used for
+ * the legacy hierarchies.
+ */
int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
{
+ struct cftype *cft;
+
+ for (cft = cfts; cft && cft->name[0] != '\0'; cft++)
+ cft->flags |= CFTYPE_INSANE;
return cgroup_add_cftypes(ss, cfts);
}
@@ -4893,9 +4931,19 @@ int __init cgroup_init(void)
* disabled flag and cftype registration needs kmalloc,
* both of which aren't available during early_init.
*/
- if (!ss->disabled) {
- cgrp_dfl_root.subsys_mask |= 1 << ss->id;
- WARN_ON(cgroup_add_cftypes(ss, ss->legacy_cftypes));
+ if (ss->disabled)
+ continue;
+
+ cgrp_dfl_root.subsys_mask |= 1 << ss->id;
+
+ if (cgroup_legacy_files_on_dfl && !ss->dfl_cftypes)
+ ss->dfl_cftypes = ss->legacy_cftypes;
+
+ if (ss->dfl_cftypes == ss->legacy_cftypes) {
+ WARN_ON(cgroup_add_cftypes(ss, ss->dfl_cftypes));
+ } else {
+ WARN_ON(cgroup_add_dfl_cftypes(ss, ss->dfl_cftypes));
+ WARN_ON(cgroup_add_legacy_cftypes(ss, ss->legacy_cftypes));
}
}
@@ -5291,6 +5339,14 @@ static int __init cgroup_disable(char *str)
}
__setup("cgroup_disable=", cgroup_disable);
+static int __init cgroup_set_legacy_files_on_dfl(char *str)
+{
+ printk("cgroup: using legacy files on the default hierarchy\n");
+ cgroup_legacy_files_on_dfl = true;
+ return 0;
+}
+__setup("cgroup__DEVEL__legacy_files_on_dfl", cgroup_set_legacy_files_on_dfl);
+
/**
* css_tryget_online_from_dir - get corresponding css from a cgroup dentry
* @dentry: directory dentry of interest