Wanlong Gao <gaowanl...@cn.fujitsu.com> writes:
>   */
>  static u16 virtnet_select_queue(struct net_device *dev, struct sk_buff *skb)
>  {
> -     int txq = skb_rx_queue_recorded(skb) ? skb_get_rx_queue(skb) :
> -               smp_processor_id();
> +     int txq = 0;
> +
> +     if (skb_rx_queue_recorded(skb))
> +             txq = skb_get_rx_queue(skb);
> +     else if ((txq = per_cpu(vq_index, smp_processor_id())) == -1)
> +             txq = 0;

You should use __get_cpu_var() instead of smp_processor_id() here, ie:

        else if ((txq = __get_cpu_var(vq_index)) == -1)

And AFAICT, no reason to initialize txq to 0 to start with.

So:

        int txq;

        if (skb_rx_queue_recorded(skb))
                txq = skb_get_rx_queue(skb);
        else {
                txq = __get_cpu_var(vq_index);
                if (txq == -1)
                        txq = 0;
        }

Now, just to confirm, I assume this can happen even if we use vq_index,
right, because of races with virtnet_set_channels?

        while (unlikely(txq >= dev->real_num_tx_queues))
                txq -= dev->real_num_tx_queues;


Thanks,
Rusty.
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