cgroup: fix harmless bugs in cgroup_load_subsys() fail path and cgroup_unload_subsys()
* If idr init fails, cgroup_load_subsys() cleared dummytop->subsys[] before calilng ->destroy() making CSS inaccessible to the callback, and didn't unlink ss->sibling. As no modular controller uses ->use_id, this doesn't cause any actual problems. * cgroup_unload_subsys() was forgetting to free idr, call ->pre_destroy() and clear ->active. As there currently is no modular controller which uses ->use_id, ->pre_destroy() or ->active, this doesn't cause any actual problems. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
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@ -4420,9 +4420,10 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
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if (ss->use_id) {
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int ret = cgroup_init_idr(ss, css);
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if (ret) {
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dummytop->subsys[ss->subsys_id] = NULL;
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ss->destroy(dummytop);
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dummytop->subsys[ss->subsys_id] = NULL;
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subsys[ss->subsys_id] = NULL;
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list_del_init(&ss->sibling);
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mutex_unlock(&cgroup_mutex);
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return ret;
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}
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@ -4490,7 +4491,19 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss)
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*/
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BUG_ON(ss->root != &rootnode);
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/* ->pre_destroy() should be called outside cgroup_mutex for now */
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if (ss->pre_destroy)
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ss->pre_destroy(dummytop);
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mutex_lock(&cgroup_mutex);
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ss->active = 0;
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if (ss->use_id) {
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idr_remove_all(&ss->idr);
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idr_destroy(&ss->idr);
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}
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/* deassign the subsys_id */
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subsys[ss->subsys_id] = NULL;
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