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Subject: Re: [PATCH] vrf: Fix possible NULL pointer oops when delete nic
To:     David Ahern <dsahern@gmail.com>, <dsahern@kernel.org>,
        <shrijeet@gmail.com>, <davem@davemloft.net>
CC:     <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <hujunwei4@huawei.com>, <xuhanbing@huawei.com>
References: <60e827cb-2bba-2b7e-55dc-651103e9905f@huawei.com>
 <7fe948a8-debd-e336-9584-e66153e90701@gmail.com>
From:   "wangxiaogang (F)" <wangxiaogang3@huawei.com>
Message-ID: <bead86fd-ae33-219f-0601-d80b57695d3c@huawei.com>
Date:   Mon, 18 Nov 2019 11:16:31 +0800
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On 2019/11/16 0:59, David Ahern wrote:
> On 11/14/19 11:22 PM, wangxiaogang (F) wrote:
>> diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c
>> index b8228f5..86c4b8c 100644
>> --- a/drivers/net/vrf.c
>> +++ b/drivers/net/vrf.c
>> @@ -1427,6 +1427,9 @@ static int vrf_device_event(struct notifier_block *unused,
>>  			goto out;
>>
>>  		vrf_dev = netdev_master_upper_dev_get(dev);
>> +		if (!vrf_dev)
>> +			goto out;
>> +
>>  		vrf_del_slave(vrf_dev, dev);
>>  	}
>>  out:
> 
> BTW, I believe this is the wrong fix. A device can not be a VRF slave
> AND not have an upper device. Something is fundamentally wrong.
> 
> 

this problem occurs when our testers deleted the NIC and vrf in parallel.
I will try to recurring this problem later.