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    Subject[PATCH 04/16] cgroup: factor out cgroup_create() out of cgroup_mkdir()
    Date
    We're in the process of refactoring cgroup and css management paths to
    separate them out to eventually allow cgroups which aren't visible
    through cgroup fs. This patch factors out cgroup_create() out of
    cgroup_mkdir(). cgroup_create() contains all internal object creation
    and initialization. cgroup_mkdir() uses cgroup_create() to create the
    internal cgroup and adds interface directory and file creation.

    This patch doesn't cause any behavior differences.

    Signed-off-by: Tejun Heo <tj@kernel.org>
    ---
    kernel/cgroup.c | 72 ++++++++++++++++++++++++++++++++++-----------------------
    1 file changed, 43 insertions(+), 29 deletions(-)

    diff --git a/kernel/cgroup.c b/kernel/cgroup.c
    index 204f78a..070c078 100644
    --- a/kernel/cgroup.c
    +++ b/kernel/cgroup.c
    @@ -4884,33 +4884,19 @@ static struct cgroup_subsys_state *css_create(struct cgroup *cgrp,
    return ERR_PTR(err);
    }

    -static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
    - umode_t mode)
    +static struct cgroup *cgroup_create(struct cgroup *parent)
    {
    - struct cgroup *parent, *cgrp, *tcgrp;
    - struct cgroup_root *root;
    + struct cgroup_root *root = parent->root;
    struct cgroup_subsys *ss;
    - struct kernfs_node *kn;
    - int level, ssid, ret;
    -
    - /* Do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable.
    - */
    - if (strchr(name, '\n'))
    - return -EINVAL;
    -
    - parent = cgroup_kn_lock_live(parent_kn);
    - if (!parent)
    - return -ENODEV;
    - root = parent->root;
    - level = parent->level + 1;
    + struct cgroup *cgrp, *tcgrp;
    + int level = parent->level + 1;
    + int ssid, ret;

    /* allocate the cgroup and its ID, 0 is reserved for the root */
    cgrp = kzalloc(sizeof(*cgrp) +
    sizeof(cgrp->ancestor_ids[0]) * (level + 1), GFP_KERNEL);
    - if (!cgrp) {
    - ret = -ENOMEM;
    - goto out_unlock;
    - }
    + if (!cgrp)
    + return ERR_PTR(-ENOMEM);

    ret = percpu_ref_init(&cgrp->self.refcnt, css_release, 0, GFP_KERNEL);
    if (ret)
    @@ -4974,6 +4960,40 @@ static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
    cgroup_refresh_subtree_ss_mask(cgrp);
    }

    + return cgrp;
    +
    +out_cancel_ref:
    + percpu_ref_exit(&cgrp->self.refcnt);
    +out_free_cgrp:
    + kfree(cgrp);
    + return ERR_PTR(ret);
    +out_destroy:
    + cgroup_destroy_locked(cgrp);
    + return ERR_PTR(ret);
    +}
    +
    +static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
    + umode_t mode)
    +{
    + struct cgroup *parent, *cgrp;
    + struct cgroup_subsys *ss;
    + struct kernfs_node *kn;
    + int ssid, ret;
    +
    + /* do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable */
    + if (strchr(name, '\n'))
    + return -EINVAL;
    +
    + parent = cgroup_kn_lock_live(parent_kn);
    + if (!parent)
    + return -ENODEV;
    +
    + cgrp = cgroup_create(parent);
    + if (IS_ERR(cgrp)) {
    + ret = PTR_ERR(cgrp);
    + goto out_unlock;
    + }
    +
    /* create the directory */
    kn = kernfs_create_dir(parent->kn, name, mode, cgrp);
    if (IS_ERR(kn)) {
    @@ -5008,17 +5028,11 @@ static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
    ret = 0;
    goto out_unlock;

    -out_cancel_ref:
    - percpu_ref_exit(&cgrp->self.refcnt);
    -out_free_cgrp:
    - kfree(cgrp);
    +out_destroy:
    + cgroup_destroy_locked(cgrp);
    out_unlock:
    cgroup_kn_unlock(parent_kn);
    return ret;
    -
    -out_destroy:
    - cgroup_destroy_locked(cgrp);
    - goto out_unlock;
    }

    /*
    --
    2.5.0
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