Subject: Re: [PATCH] virtio_net: zero is an invald queue_pairs number

From: Jason Wang <[email-masked]>
Date: Mon, 21 Apr 2014 14:45:25 +0800

On 04/21/2014 02:32 PM, Jason Wang wrote:
> On 04/18/2014 01:45 PM, Amos Kong wrote:
>> Execute "ethtool -L eth0 combined 0" in guest, if multiqueue
>> is enabled, virtnet_send_command() will return -EINVAL error,
>> there is a validation in QEMU.
>>
>> But if multiqueue is disabled, virtnet_set_queues() will just
>> return zero (success). We should return error for this situation.
>>
>> Signed-off-by: Amos Kong <[email-masked]>
>> ---
>>  drivers/net/virtio_net.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>> index 7b68746..8a852b5 100644
>> --- a/drivers/net/virtio_net.c
>> +++ b/drivers/net/virtio_net.c
>> @@ -1285,7 +1285,7 @@ static int virtnet_set_channels(struct net_device *dev,
>>  	if (channels->rx_count || channels->tx_count || channels->other_count)
>>  		return -EINVAL;
>>  
>> -	if (queue_pairs > vi->max_queue_pairs)
>> +	if (queue_pairs > vi->max_queue_pairs || queue_pairs == 0)
>>  		return -EINVAL;
>>  
>>  	get_online_cpus();
> Acked-by:  Jason Wang <[email-masked]>

Looking at virtnet_set_queues(), it will return success even if no cvq
and no mq support. This is wrong. We need return error in this case.
We'd better fix it and check the its return value in virtnet_restore().

With this fix, there's no need for us to check queue_pairs against zero
like what this patch does.