Re: [PATCH 2/8] cgroup: implement cgroup_from_id()

From: Tejun Heo
Date: Mon Apr 08 2013 - 11:49:03 EST

Oops, one more thing.

On Mon, Apr 08, 2013 at 04:20:59PM +0800, Li Zefan wrote:
> - cgrp->id = ida_simple_get(&root->cgroup_ida, 1, 0, GFP_KERNEL);
> + cgrp->id = idr_alloc(&root->cgroup_idr, cgrp, 1, 0, GFP_KERNEL);

This will allow lookups to return half-initialized cgroup, which
shouldn't happen. Either idr_alloc() should be moved to after
initialization of other fields are finished, or it should be called
with NULL @ptr with idr_replace() added at the end to install @cgrp.

Similarly, the removal path should guarantee that the object is
removed from idr *before* its grace period starts.


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