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>

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 888fba457bb3bda8a3cf7a7cfea5b3ce80056497..40e0df6c2a2f57ff9a4b152acdd79a5deed003af 100644 (file)
--- 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);
 
 }