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Subject: Re: [PATCH 07/10] staging: erofs: separate into init_once / always
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CC:     <devel@driverdev.osuosl.org>, <linux-erofs@lists.ozlabs.org>,
        Chao Yu <yuchao0@huawei.com>,
        LKML <linux-kernel@vger.kernel.org>, <weidu.du@huawei.com>,
        Miao Xie <miaoxie@huawei.com>
References: <20181120143425.43637-1-gaoxiang25@huawei.com>
 <20181120143425.43637-8-gaoxiang25@huawei.com>
 <20181122102339.GG3189@kroah.com>
From:   Gao Xiang <gaoxiang25@huawei.com>
Message-ID: <66b90226-5d0e-7344-5220-908aa243b014@huawei.com>
Date:   Thu, 22 Nov 2018 18:34:10 +0800
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Hi Greg,

On 2018/11/22 18:23, Greg Kroah-Hartman wrote:
>> +
>> +	DBG_BUGON(work->nr_pages);
>> +	DBG_BUGON(work->vcnt);
> How can these ever be triggered?  I understand the need for debugging
> code when you are writing code, but at this point it shouldn't be needed
> anymore, right?

I need to avoid some fields is not 0 when the new workgroup is created (because
work->nr_pages and work->vcnt == 0 usually after the previous workgroup is freed).
But that is not obvious, it is promised by the current logic.

In order to not introduce such a issue in the future, or there are some potential
race (work->nr_pages and work->vcnt != 0 when the previous workgroup == 0), it need
to be noticed to developpers as early as possible.

Thanks,
Gao Xiang

> 
> thanks,
> 
> greg k-h