cgroup: convert to idr_alloc()

Convert to the much saner new idr interface.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 19 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 888fba457bb3..40e0df6c2a2f 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -5320,7 +5320,7 @@ EXPORT_SYMBOL_GPL(free_css_id);
 static struct css_id *get_new_cssid(struct cgroup_subsys *ss, int depth)
 {
         struct css_id *newid;
-        int myid, error, size;
+        int ret, size;
 
         BUG_ON(!ss->use_id);
 
@@ -5328,35 +5328,24 @@ static struct css_id *get_new_cssid(struct cgroup_subsys *ss, int depth)
         newid = kzalloc(size, GFP_KERNEL);
         if (!newid)
                 return ERR_PTR(-ENOMEM);
-        /* get id */
-        if (unlikely(!idr_pre_get(&ss->idr, GFP_KERNEL))) {
-                error = -ENOMEM;
-                goto err_out;
-        }
+
+        idr_preload(GFP_KERNEL);
         spin_lock(&ss->id_lock);
         /* Don't use 0. allocates an ID of 1-65535 */
-        error = idr_get_new_above(&ss->idr, newid, 1, &myid);
+        ret = idr_alloc(&ss->idr, newid, 1, CSS_ID_MAX + 1, GFP_NOWAIT);
         spin_unlock(&ss->id_lock);
+        idr_preload_end();
 
         /* Returns error when there are no free spaces for new ID.*/
-        if (error) {
-                error = -ENOSPC;
+        if (ret < 0)
                 goto err_out;
-        }
-        if (myid > CSS_ID_MAX)
-                goto remove_idr;
 
-        newid->id = myid;
+        newid->id = ret;
         newid->depth = depth;
         return newid;
-remove_idr:
-        error = -ENOSPC;
-        spin_lock(&ss->id_lock);
-        idr_remove(&ss->idr, myid);
-        spin_unlock(&ss->id_lock);
 err_out:
         kfree(newid);
-        return ERR_PTR(error);
+        return ERR_PTR(ret);
 
 }