linux-kernel - Re: [PATCH] uacce: unmap remaining mmapping from user space

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Message-ID: <cf1f7ec2-7181-63fd-598d-b74d5a3efa15@linaro.org>
Date:   Tue, 25 Feb 2020 16:33:37 +0800
From:   zhangfei <zhangfei.gao@...aro.org>
To:     Xu Zaibo <xuzaibo@...wei.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Arnd Bergmann <arnd@...db.de>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        jonathan.cameron@...wei.com, dave.jiang@...el.com,
        grant.likely@....com, jean-philippe <jean-philippe@...aro.org>,
        Jerome Glisse <jglisse@...hat.com>,
        ilias.apalodimas@...aro.org, francois.ozog@...aro.org,
        kenneth-lee-2012@...mail.com, Wangzhou <wangzhou1@...ilicon.com>,
        "haojian . zhuang" <haojian.zhuang@...aro.org>,
        guodong.xu@...aro.org
Cc:     iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        linux-accelerators@...ts.ozlabs.org, linux-crypto@...r.kernel.org
Subject: Re: [PATCH] uacce: unmap remaining mmapping from user space

Hi, Zaibo

On 2020/2/24 下午3:17, Xu Zaibo wrote:
>>   @@ -585,6 +595,13 @@ void uacce_remove(struct uacce_device *uacce)
>>           cdev_device_del(uacce->cdev, &uacce->dev);
>>       xa_erase(&uacce_xa, uacce->dev_id);
>>       put_device(&uacce->dev);
>> +
>> +    /*
>> +     * unmap remainning mapping from user space, preventing user still
>> +     * access the mmaped area while parent device is already removed
>> +     */
>> +    if (uacce->inode)
>> +        unmap_mapping_range(uacce->inode->i_mapping, 0, 0, 1);
> Should we unmap them at the first of 'uacce_remove',  and before 
> 'uacce_put_queue'?
>
We can do this,
Though it does not matter, since user space can not interrupt kernel 
function uacce_remove.

Thanks