(2013/04/08 17:20), Li Zefan wrote: > This will be used as a replacement for css_lookup(). > > Signed-off-by: Li Zefan <[email protected]> > --- > include/linux/cgroup.h | 1 + > kernel/cgroup.c | 31 +++++++++++++++++++++++++------ > 2 files changed, 26 insertions(+), 6 deletions(-) > > diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h > index 96072e4..6ae8ae1 100644 > --- a/include/linux/cgroup.h > +++ b/include/linux/cgroup.h > @@ -732,6 +732,7 @@ unsigned short css_depth(struct cgroup_subsys_state *css); > struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id); > > bool cgroup_is_ancestor(struct cgroup *child, struct cgroup *root); > +struct cgroup *cgroup_from_id(struct cgroup_subsys *ss, int id); > > #else /* !CONFIG_CGROUPS */ > > diff --git a/kernel/cgroup.c b/kernel/cgroup.c > index e87872c..5ae1e87 100644 > --- a/kernel/cgroup.c > +++ b/kernel/cgroup.c > @@ -139,7 +139,7 @@ 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]; > @@ -908,7 +908,7 @@ static void cgroup_free_fn(struct work_struct *work) > > simple_xattrs_free(&cgrp->xattrs); > > - ida_simple_remove(&cgrp->root->cgroup_ida, cgrp->id); > + idr_remove(&cgrp->root->cgroup_idr, cgrp->id); > kfree(rcu_dereference_raw(cgrp->name)); > kfree(cgrp); > } > @@ -1512,7 +1512,8 @@ 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); > + idr_init(&root->cgroup_idr); > + > if (opts->release_agent) > strcpy(root->release_agent_path, opts->release_agent); > if (opts->name) > @@ -1531,7 +1532,7 @@ static void cgroup_drop_root(struct cgroupfs_root *root) > spin_lock(&hierarchy_id_lock); > ida_remove(&hierarchy_ida, root->hierarchy_id); > spin_unlock(&hierarchy_id_lock); > - ida_destroy(&root->cgroup_ida); > + idr_destroy(&root->cgroup_idr); > kfree(root); > } > > @@ -1645,6 +1646,11 @@ 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, 0, GFP_KERNEL); > + if (root_cgrp->id < 0) > + goto unlock_drop; > + > /* Check for name clashes with existing mounts */ > ret = -EBUSY; > if (strlen(root->name)) > @@ -4104,7 +4110,7 @@ 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); > + cgrp->id = idr_alloc(&root->cgroup_idr, cgrp, 1, 0, GFP_KERNEL); > if (cgrp->id < 0) > goto err_free_name; > > @@ -4215,7 +4221,7 @@ 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: > @@ -5320,6 +5326,19 @@ bool cgroup_is_ancestor(struct cgroup *child, struct > cgroup *root) > return (child == root); > } > > +/** > + * cgroup_from_id - lookup cgroup by id > + * @ss: cgroup subsys to be looked into. > + * @id: the id > + * > + * Returns pointer to cgroup if there is valid one with id. > + * NULL if not. Should be called under rcu_read_lock() > + */ > +struct cgroup *cgroup_from_id(struct cgroup_subsys *ss, int id) > +{ > + return idr_find(&ss->root->cgroup_idr, id); > +} > +
How about checking cgroup_populated_dir() have been called once ? If not, returning NULL. Thanks, -Kame -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
