diff options
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 23 |
1 files changed, 17 insertions, 6 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index dbc84f7d23b..3ef677d314b 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -189,9 +189,13 @@ struct cgroup_event { static LIST_HEAD(roots); static int root_count; +/* + * Hierarchy ID allocation and mapping. It follows the same exclusion + * rules as other root ops - both cgroup_mutex and cgroup_root_mutex for + * writes, either for reads. + */ static DEFINE_IDA(hierarchy_ida); static int next_hierarchy_id; -static DEFINE_SPINLOCK(hierarchy_id_lock); /* dummytop is a shorthand for the dummy hierarchy's top cgroup */ #define dummytop (&rootnode.top_cgroup) @@ -1430,10 +1434,12 @@ static int cgroup_init_root_id(struct cgroupfs_root *root) { int ret; + lockdep_assert_held(&cgroup_mutex); + lockdep_assert_held(&cgroup_root_mutex); + do { if (!ida_pre_get(&hierarchy_ida, GFP_KERNEL)) return -ENOMEM; - spin_lock(&hierarchy_id_lock); /* Try to allocate the next unused ID */ ret = ida_get_new_above(&hierarchy_ida, next_hierarchy_id, &root->hierarchy_id); @@ -1446,18 +1452,17 @@ static int cgroup_init_root_id(struct cgroupfs_root *root) /* Can only get here if the 31-bit IDR is full ... */ BUG_ON(ret); } - spin_unlock(&hierarchy_id_lock); } while (ret); return 0; } static void cgroup_exit_root_id(struct cgroupfs_root *root) { + lockdep_assert_held(&cgroup_mutex); + lockdep_assert_held(&cgroup_root_mutex); + if (root->hierarchy_id) { - spin_lock(&hierarchy_id_lock); ida_remove(&hierarchy_ida, root->hierarchy_id); - spin_unlock(&hierarchy_id_lock); - root->hierarchy_id = 0; } } @@ -4656,8 +4661,14 @@ int __init cgroup_init(void) hash_add(css_set_table, &init_css_set.hlist, key); /* allocate id for the dummy hierarchy */ + mutex_lock(&cgroup_mutex); + mutex_lock(&cgroup_root_mutex); + BUG_ON(cgroup_init_root_id(&rootnode)); + mutex_unlock(&cgroup_root_mutex); + mutex_unlock(&cgroup_mutex); + cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj); if (!cgroup_kobj) { err = -ENOMEM; |