Re: [PATCH v2 2/2] net: io_uring/zcrx: call netdev_queue_get_dma_dev() under instance lock

[David Wei <dw@davidwei.uk>]

On 2025-10-29 16:54, Jakub Kicinski wrote:
> On Wed, 29 Oct 2025 16:16:54 -0700 David Wei wrote:
>> +	ifq->netdev = netdev_get_by_index_lock(current->nsproxy->net_ns, reg.if_idx);
>>   	if (!ifq->netdev) {
>>   		ret = -ENODEV;
>> -		goto err;
>> +		goto netdev_unlock;
>>   	}
>>   
>>   	ifq->dev = netdev_queue_get_dma_dev(ifq->netdev, reg.if_rxq);
>>   	if (!ifq->dev) {
>>   		ret = -EOPNOTSUPP;
>> -		goto err;
>> +		goto netdev_unlock;
>>   	}
>> +	netdev_hold(ifq->netdev, &ifq->netdev_tracker, GFP_KERNEL);
>>   	get_device(ifq->dev);
>>   
>>   	ret = io_zcrx_create_area(ifq, &area);
>>   	if (ret)
>> -		goto err;
>> +		goto netdev_unlock;
> 
> Without looking at larger context this looks sus.
> You're jumping to the same label before and after you took the ref on
> the netdev..

Sorry you're right, and actually io_zcrx_ifq_free() does netdev_put()
unconditionally. I'll correct this in v3.