We want to be able to lookup a hierarchy from its id and cyclic
allocation is a whole lot simpler with idr. Convert to idr and use
idr_alloc_cyclc().
Signed-off-by: Tejun Heo <t...@kernel.org>
---
kernel/cgroup.c | 28 ++++++++--------------------
1 file changed, 8 insertions(+), 20 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index e15bdb7..75d85e8 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -242,8 +242,7 @@ static int root_count;
* 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_IDR(cgroup_hierarchy_idr);
/* dummytop is a shorthand for the dummy hierarchy's top cgroup */
#define dummytop (&rootnode.top_cgroup)
@@ -1458,27 +1457,16 @@ static void init_cgroup_root(struct cgroupfs_root *root)
static int cgroup_init_root_id(struct cgroupfs_root *root)
{
- int ret;
+ int id;
lockdep_assert_held(&cgroup_mutex);
lockdep_assert_held(&cgroup_root_mutex);
- do {
- if (!ida_pre_get(&hierarchy_ida, GFP_KERNEL))
- return -ENOMEM;
- /* Try to allocate the next unused ID */
- ret = ida_get_new_above(&hierarchy_ida, next_hierarchy_id,
- &root->hierarchy_id);
- if (ret == -ENOSPC)
- /* Try again starting from 0 */
- ret = ida_get_new(&hierarchy_ida, &root->hierarchy_id);
- if (!ret) {
- next_hierarchy_id = root->hierarchy_id + 1;
- } else if (ret != -EAGAIN) {
- /* Can only get here if the 31-bit IDR is full ... */
- BUG_ON(ret);
- }
- } while (ret);
+ id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, 2, 0, GFP_KERNEL);
+ if (id < 0)
+ return id;
+
+ root->hierarchy_id = id;
return 0;
}
@@ -1488,7 +1476,7 @@ static void cgroup_exit_root_id(struct cgroupfs_root
*root)
lockdep_assert_held(&cgroup_root_mutex);
if (root->hierarchy_id) {
- ida_remove(&hierarchy_ida, root->hierarchy_id);
+ idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id);
root->hierarchy_id = 0;
}
}
--
1.8.1.4
--
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