Re: [PATCH v2 1/3] cgroup: fix mount failure in a corner case

From: Li Zefan
Date: Sun Jun 29 2014 - 21:41:36 EST


On 2014/6/28 19:58, Tejun Heo wrote:
> Hello, Li.
>
> On Fri, Jun 27, 2014 at 05:13:12PM +0800, Li Zefan wrote:
>> + for_each_subsys(ss, i) {
>> + if (!(opts.subsys_mask & (1 << i)) ||
>> + ss->root == &cgrp_dfl_root)
>> + continue;
>> +
>> + if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt)) {
>> + mutex_unlock(&cgroup_mutex);
>> + msleep(10);
>> + ret = restart_syscall();
>> + goto out_free;
>> + }
>
> Why not just put it immediately? We know that it's not gonna be
> destroyed while holding cgroup_mutex. It may look a bit weird but
> this is a pretty special case anyway and deferring put doesn't buy
> anything.
>

Yeah, this is better. :)

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