Hello,
Currently a css's (cgroup_subsys_state) lifetime is tied to that of
the cgroup it's attached to. css's are created when the cgroup is
created and destroyed together. The access rules depend on it too -
e.g. css's can be dereferenced while holding RCU read lock because
cgroup is protected with RCU.
With the planned unified hierarchy, we'll be dynamically creating and
destroying css's through the lifetime of a cgroup, so we can no longer
hitch css lifetime management onto cgroup's. This patchset separates
out css lifetime management from that of cgroup. After the patchset,
each css is individually RCU protected.
This patchset contains the following 14 patches.
0001-cgroup-always-use-cgroup_css.patch
0002-cgroup-rename-cgroup_subsys_state-dput_work-and-its-.patch
0003-cgroup-add-cgroup_subsys_state-parent.patch
0004-cgroup-cgroup_css_from_dir-now-should-be-called-with.patch
0005-cgroup-make-cgroup_file_open-rcu_read_lock-around-cg.patch
0006-cgroup-add-__rcu-modifier-to-cgroup-subsys.patch
0007-cgroup-reorganize-css-init-exit-paths.patch
0008-cgroup-move-cgroup-subsys-assignment-to-online_css.patch
0009-cgroup-bounce-cgroup_subsys_state-ref-kill-confirmat.patch
0010-cgroup-replace-cgroup-css_kill_cnt-with-nr_css.patch
0011-cgroup-decouple-cgroup_subsys_state-destruction-from.patch
0012-cgroup-factor-out-kill_css.patch
0013-cgroup-move-subsys-file-removal-to-kill_css.patch
0014-cgroup-RCU-protect-each-cgroup_subsys_state-release.patch
The patchset is on top of
cgroup/for-3.12 61584e3f4 ("cgroup: Merge branch 'for-3.11-fixes' into for-3.12")
+ [1] cgroup: use cgroup_subsys_state as the primary subsystem interface handle
+ [2] cgroup: cgroup: make css_for_each_descendant() and friends include the origin css in the iteration
and available in the following branch.
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git review-rcufy-css
diffstat follows.
include/linux/cgroup.h | 24 +-
kernel/cgroup.c | 423 +++++++++++++++++++++++++++++--------------------
kernel/events/core.c | 3
3 files changed, 268 insertions(+), 182 deletions(-)
Thanks.
--
tejun
[1] https://lkml.org/lkml/2013/8/1/722
[2] https://lkml.org/lkml/2013/8/4/130
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