Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH] net: 8390: Fix possible data races in __ei_get_stats
To:     Eric Dumazet <eric.dumazet@gmail.com>, davem@davemloft.net,
        fthain@telegraphics.com.au, joe@perches.com
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20180507140809.28847-1-baijiaju1990@gmail.com>
 <e48345b4-fe9f-d267-777b-6a51baba0307@gmail.com>
 <d4de4f6c-c697-fde5-9d31-d8792621bfb5@gmail.com>
 <c336fdb9-4865-4729-d34b-84dd0bfc9af5@gmail.com>
 <6fe51782-2169-53c8-9bac-1715262e716d@gmail.com>
 <dddbec3f-4b63-3e70-d857-4980135d6f31@gmail.com>
From:   Jia-Ju Bai <baijiaju1990@gmail.com>
Message-ID: <bde101fd-2bd1-ddc8-ebeb-4145963e95d1@gmail.com>
Date:   Tue, 8 May 2018 14:47:38 +0800
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101
 Thunderbird/52.2.0
MIME-Version: 1.0
In-Reply-To: <dddbec3f-4b63-3e70-d857-4980135d6f31@gmail.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Content-Language: en-US
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


On 2018/5/8 13:04, Eric Dumazet wrote:
>
> On 05/07/2018 07:16 PM, Jia-Ju Bai wrote:
>
>> Yes, "&dev->stats" will not change, because it is a fixed address.
>> But the field data in "dev->stats" is changed (rx_frame_errors, rx_crc_errors and rx_missed_errors).
>> So if the driver returns "&dev->stats" without lock protection (like on line 858), the field data value of this return value can be the changed field data value or unchanged field data value.
>
> We do not care.
>
> This function can be called by multiple cpus at the same time.
>
> As soon as one cpu returns from it, another cpu can happily modify dev->stats.ANYFIELD.
>
> Your patch fixes nothing at all.
>

Okay, thanks.
I also find that my patch does not work...


Best wishes,
Jia-Ju Bai