lkml.org 
[lkml]   [2013]   [Aug]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCHSET cgroup/for-3.12] cgroup: use cgroup_subsys_state as the primary subsystem interface handle
    On 2013/8/2 5:49, Tejun Heo wrote:
    > Hello,
    >
    > Currently, struct cgroup * is used as the main interface handle
    > between cgroup core and its subsystems, which works but is a bit
    > clunky because subsystems usually care much more about css's
    > (cgroup_subsys_state) a lot more than cgroups, which is natural as a
    > css is the intersection between a cgroup and a subsystem.
    >
    > In addition to being a bit clunky, dealing with cgroups directly pose
    > a bit of trouble for the planned unified hierarchy support on two
    > fronts. First, most iterations become subsystem dependent as task
    > membership is affected by which subtree has the specific subsystem
    > enabled and thus require specifying which subsystem the iteration is
    > for, which is automatically achieved if the interfaces deal with css's
    > instead of cgroups.
    >
    > Second, as css's may be created, attached, detached and destroyed
    > dynamically multiple times across the lifetime of a given cgroup as
    > they're enabled and disabled, which makes cgroup -> css mapping much
    > more difficult to synchronize. Giving out cgroup to subsystems and
    > then requiring them to take the extra steps to deal with their css's
    > coming and going dynamically is a lot more fragile than cgroup core
    > proper handling it internally and giving out the resulting css's to
    > subsystems.
    >
    > So, this patchset converts all cgroup subsystem APIs to deal with
    > css's instead of cgroups. The patchset is fairly large but most of
    > the conversions, while being tedious, aren't complex. At the end of
    > series, subsystems no longer make cgroup -> css mapping themselves and
    > cgroup_css() - formerly cgroup_subsys_state() - is made internal to
    > cgroup core proper.
    >
    > This is a rather large update to the interface and likely to play as a
    > barrier when porting commits, which is inconvenient but also provides
    > an opportunity to clean up the API where we can as doing so won't
    > significantly raise the level of inconvenience. As such, this
    > patchset contains some API cleanups and I'll probably follow up with
    > further API updates that I've been meaning to do and, if you have some
    > good idea to clean up cgroup internal API, this probably is a good
    > time to submit it.
    >
    > This patchset contains the following 23 patches.
    >
    > 0001-cgroup-s-cgroup_subsys_state-cgroup_css-s-task_subsy.patch
    > 0002-cpuset-drop-const-qualifiers-from-struct-cpuset-inst.patch
    > 0003-netprio_cgroup-pass-around-css-instead-of-cgroup-and.patch
    > 0004-hugetlb_cgroup-pass-around-hugetlb_cgroup-instead-of.patch
    > 0005-cgroup-add-subsystem-pointer-to-cgroup_subsys_state.patch
    > 0006-cgroup-add-update-accessors-which-obtain-subsys-spec.patch
    > 0007-cgroup-add-css_parent.patch
    > 0008-cgroup-pass-around-cgroup_subsys_state-instead-of-cg.patch
    > 0009-cgroup-add-subsys-backlink-pointer-to-cftype.patch
    > 0010-cgroup-pin-cgroup_subsys_state-when-opening-a-cgroup.patch
    > 0011-cgroup-add-cgroup-dummy_css.patch
    > 0012-cgroup-pass-around-cgroup_subsys_state-instead-of-cg.patch
    > 0013-cgroup-convert-cgroup_next_sibling-to-cgroup_next_ch.patch
    > 0014-cgroup-always-use-cgroup_next_child-to-walk-the-chil.patch
    > 0015-cgroup-make-hierarchy-iterators-deal-with-cgroup_sub.patch
    > 0016-cgroup-relocate-cgroup_advance_iter.patch
    > 0017-cgroup-rename-cgroup_iter-to-cgroup_task_iter.patch
    > 0018-cgroup-make-cgroup_task_iter-remember-the-cgroup-bei.patch
    > 0019-cgroup-remove-struct-cgroup_scanner.patch
    > 0020-cgroup-make-task-iterators-deal-with-cgroup_subsys_s.patch
    > 0021-cgroup-make-cftype-un-register_event-deal-with-cgrou.patch
    > 0022-cgroup-make-cgroup_taskset-deal-with-cgroup_subsys_s.patch
    > 0023-cgroup-unexport-cgroup_css.patch
    >

    Looks good to me!

    Acked-by: Li Zefan <lizefan@huawei.com>



    \
     
     \ /
      Last update: 2013-08-02 05:41    [W:4.074 / U:0.352 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site