lkml.org 
[lkml]   [2013]   [Jul]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[PATCH v4 1/8] cgroup: convert cgroup_ida to cgroup_idr
    This enables us to lookup a cgroup by its id.

    v4:
    - add a comment for idr_remove() in cgroup_offline_fn().

    v3:
    - on success, idr_alloc() returns the id but not 0, so fix the BUG_ON()
    in cgroup_init().
    - pass the right value to idr_alloc() so that the id for dummy cgroup is 0.

    Signed-off-by: Li Zefan <lizefan@huawei.com>
    Reviewed-by: Michal Hocko <mhocko@suse.cz>
    ---
    include/linux/cgroup.h | 4 ++--
    kernel/cgroup.c | 33 +++++++++++++++++++++++++++------
    2 files changed, 29 insertions(+), 8 deletions(-)

    diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
    index 297462b..2bd052d 100644
    --- a/include/linux/cgroup.h
    +++ b/include/linux/cgroup.h
    @@ -161,7 +161,7 @@ struct cgroup_name {
    struct cgroup {
    unsigned long flags; /* "unsigned long" so bitops work */

    - int id; /* ida allocated in-hierarchy ID */
    + int id; /* idr allocated in-hierarchy ID */

    /*
    * We link our 'sibling' struct into our parent's 'children'.
    @@ -322,7 +322,7 @@ struct cgroupfs_root {
    unsigned long flags;

    /* IDs for cgroups in this hierarchy */
    - struct ida cgroup_ida;
    + struct idr cgroup_idr;

    /* The path to use for release notifications. */
    char release_agent_path[PATH_MAX];
    diff --git a/kernel/cgroup.c b/kernel/cgroup.c
    index 345fac8..a26e083 100644
    --- a/kernel/cgroup.c
    +++ b/kernel/cgroup.c
    @@ -866,8 +866,6 @@ static void cgroup_free_fn(struct work_struct *work)
    */
    dput(cgrp->parent->dentry);

    - ida_simple_remove(&cgrp->root->cgroup_ida, cgrp->id);
    -
    /*
    * Drop the active superblock reference that we took when we
    * created the cgroup. This will free cgrp->root, if we are
    @@ -1379,6 +1377,7 @@ static void init_cgroup_root(struct cgroupfs_root *root)
    cgrp->root = root;
    RCU_INIT_POINTER(cgrp->name, &root_cgroup_name);
    init_cgroup_housekeeping(cgrp);
    + idr_init(&root->cgroup_idr);
    }

    static int cgroup_init_root_id(struct cgroupfs_root *root, int start, int end)
    @@ -1451,7 +1450,6 @@ static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts)
    */
    root->subsys_mask = opts->subsys_mask;
    root->flags = opts->flags;
    - ida_init(&root->cgroup_ida);
    if (opts->release_agent)
    strcpy(root->release_agent_path, opts->release_agent);
    if (opts->name)
    @@ -1467,7 +1465,7 @@ static void cgroup_free_root(struct cgroupfs_root *root)
    /* hierarhcy ID shoulid already have been released */
    WARN_ON_ONCE(root->hierarchy_id);

    - ida_destroy(&root->cgroup_ida);
    + idr_destroy(&root->cgroup_idr);
    kfree(root);
    }
    }
    @@ -1582,6 +1580,11 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
    mutex_lock(&cgroup_mutex);
    mutex_lock(&cgroup_root_mutex);

    + root_cgrp->id = idr_alloc(&root->cgroup_idr, root_cgrp,
    + 0, 1, GFP_KERNEL);
    + if (root_cgrp->id < 0)
    + goto unlock_drop;
    +
    /* Check for name clashes with existing mounts */
    ret = -EBUSY;
    if (strlen(root->name))
    @@ -4273,7 +4276,11 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
    goto err_free_cgrp;
    rcu_assign_pointer(cgrp->name, name);

    - cgrp->id = ida_simple_get(&root->cgroup_ida, 1, 0, GFP_KERNEL);
    + /*
    + * Temporarily set the pointer to NULL, so idr_find() won't return
    + * a half-baked cgroup.
    + */
    + cgrp->id = idr_alloc(&root->cgroup_idr, NULL, 1, 0, GFP_KERNEL);
    if (cgrp->id < 0)
    goto err_free_name;

    @@ -4371,6 +4378,8 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
    }
    }

    + idr_replace(&root->cgroup_idr, cgrp, cgrp->id);
    +
    err = cgroup_addrm_files(cgrp, NULL, cgroup_base_files, true);
    if (err)
    goto err_destroy;
    @@ -4397,7 +4406,7 @@ err_free_all:
    /* Release the reference count that we took on the superblock */
    deactivate_super(sb);
    err_free_id:
    - ida_simple_remove(&root->cgroup_ida, cgrp->id);
    + idr_remove(&root->cgroup_idr, cgrp->id);
    err_free_name:
    kfree(rcu_dereference_raw(cgrp->name));
    err_free_cgrp:
    @@ -4590,6 +4599,14 @@ static void cgroup_offline_fn(struct work_struct *work)
    /* delete this cgroup from parent->children */
    list_del_rcu(&cgrp->sibling);

    + /*
    + * We should remove the cgroup object from idr before its grace
    + * period starts, so we won't be looking up a cgroup while the
    + * cgroup is being freed.
    + */
    + idr_remove(&cgrp->root->cgroup_idr, cgrp->id);
    + cgrp->id = -1;
    +
    dput(d);

    set_bit(CGRP_RELEASABLE, &parent->flags);
    @@ -4915,6 +4932,10 @@ int __init cgroup_init(void)

    BUG_ON(cgroup_init_root_id(&cgroup_dummy_root, 0, 1));

    + err = idr_alloc(&cgroup_dummy_root.cgroup_idr, cgroup_dummy_top,
    + 0, 1, GFP_KERNEL);
    + BUG_ON(err < 0);
    +
    mutex_unlock(&cgroup_root_mutex);
    mutex_unlock(&cgroup_mutex);

    --
    1.8.0.2

    \
     
     \ /
      Last update: 2013-07-31 04:21    [W:4.695 / U:0.000 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site