cgroup: fix harmless bugs in cgroup_load_subsys() fail path and cgroup_unload_subsys() (02ae7486) · Commits · 戴 / test

* 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>

kernel/cgroup.c

+14 −1

Original line number	Diff line number	Diff line
		@@ -4420,9 +4420,10 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
		if (ss->use_id) {
		int ret = cgroup_init_idr(ss, css);
		if (ret) {
		dummytop->subsys[ss->subsys_id] = NULL;
		ss->destroy(dummytop);
		dummytop->subsys[ss->subsys_id] = NULL;
		subsys[ss->subsys_id] = NULL;
		list_del_init(&ss->sibling);
		mutex_unlock(&cgroup_mutex);
		return ret;
		}
		@@ -4490,7 +4491,19 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss)
		*/
		BUG_ON(ss->root != &rootnode);

		/* ->pre_destroy() should be called outside cgroup_mutex for now */
		if (ss->pre_destroy)
		ss->pre_destroy(dummytop);

		mutex_lock(&cgroup_mutex);

		ss->active = 0;

		if (ss->use_id) {
		idr_remove_all(&ss->idr);
		idr_destroy(&ss->idr);
		}

		/* deassign the subsys_id */
		subsys[ss->subsys_id] = NULL;

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