netdev - Re: [PATCH] check the return value of ndo_select

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Date:	Mon, 9 Nov 2009 19:29:00 +0800
From:	Changli Gao <xiaosuo@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH] check the return value of ndo_select_queue()

2009/11/9 Eric Dumazet <eric.dumazet@...il.com>:
> Eric Dumazet a écrit :
>>
>> Yes, but this is a _very_ unlikely condition (a bug IMHO), so you could use :
>>
>> if (unlikely(queue_index >= dev->real_num_tx_queues)) {
>>       ...
>> }
>>
>> (This unlikely() clause is implied in WARN... macros)
>>
>
> Also, you want to trigger this message only once, or ratelimit it at least
>
>

How about this version:

        u16 queue_index;
        u16 (*ndo_select_queue)(struct net_device*, struct sk_buff*);
        unsigned int real_num_tx_queues = dev->real_num_tx_queues;

        if (real_num_tx_queues == 1) {
                queue_index = 0;
        } else if ((ndo_select_queue = dev->netdev_ops->ndo_select_queue)) {
                queue_index = ndo_select_queue(dev, skb);
                if (unlikely(queue_index >= real_num_tx_queues)) {
                        if (net_ratelimit())
                                WARN(1, "%s selects TX queue %d, "
                                     "but real number of TX queues is %d\n",
                                     dev->name, queue_index,
                                     real_num_tx_queues);
                        queue_index = 0;
                }
        } else {
                queue_index = skb_tx_hash(dev, skb);
        }

        skb_set_queue_mapping(skb, queue_index);
        return netdev_get_tx_queue(dev, queue_index);


-- 
Regards，
Changli Gao(xiaosuo@...il.com)
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