From a2dd424750807f83632a2a70293961086fd8f870 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 19 Mar 2014 10:23:55 -0400 Subject: cgroup: make cgrp_dfl_root mountable cgrp_dfl_root will be used as the default unified hierarchy. This patch makes cgrp_dfl_root mountable by making the following changes. * cgroup_init_early() now initializes cgrp_dfl_root w/ CGRP_ROOT_SANE_BEHAVIOR. The default hierarchy is always sane. * parse_cgroupfs_options() and cgroup_mount() are updated such that cgrp_dfl_root is mounted if sane_behavior is specified w/o any subsystems. * rebind_subsystems() now populates the root directory of cgrp_dfl_root. Note that the function still guarantees success of rebinding subsystems to cgrp_dfl_root. If populating fails while rebinding to cgrp_dfl_root, it whines but ignores the error. * For backward compatibility, the default hierarchy shows up in /proc/$PID/cgroup only after it's explicitly mounted so that userland which doesn't make use of it doesn't see any change. * "current_css_set_cg_links" file of debug cgroup now treats the default hierarchy the same as other hierarchies. This is visible to userland. Given that it's for debug controller, this should be fine. * While at it, implement cgroup_on_dfl() which tests whether a give cgroup is on the default hierarchy or not. The above changes make cgrp_dfl_root mostly equivalent to other controllers but the actual unified hierarchy behaviors are not implemented yet. Let's plug child cgroup creation in cgrp_dfl_root from create_cgroup() for now. Signed-off-by: Tejun Heo Acked-by: Li Zefan --- include/linux/cgroup.h | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'include/linux') diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 79993ac066c5..7e9fa505b7bb 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -250,6 +250,9 @@ enum { * * - "cgroup.clone_children" is removed. * + * - If mount is requested with sane_behavior but without any + * subsystem, the default unified hierarchy is mounted. + * * - cpuset: tasks will be kept in empty cpusets when hotplug happens * and take masks of ancestors with non-empty cpus/mems, instead of * being moved to an ancestor. @@ -468,6 +471,13 @@ struct cftype { #endif }; +extern struct cgroup_root cgrp_dfl_root; + +static inline bool cgroup_on_dfl(const struct cgroup *cgrp) +{ + return cgrp->root == &cgrp_dfl_root; +} + /* * See the comment above CGRP_ROOT_SANE_BEHAVIOR for details. This * function can be called as long as @cgrp is accessible. -- cgit v1.2.3