Re: [PATCH] net: fix problem in dequeuing from input_pkt_queue

[Changli Gao <xiaosuo@gmail.com>]

On Thu, May 20, 2010 at 7:58 AM, Tom Herbert <therbert@google.com> wrote:
>>>        napi->weight = weight_p;
>>> -       local_irq_disable();
>>>        while (work < quota) {
>>>                struct sk_buff *skb;
>>>                unsigned int qlen;
>>>
>>>                while ((skb = __skb_dequeue(&sd->process_queue))) {
>>> -                       local_irq_enable();
>>
>> we need to keep local irq disabled. If not, flush_backlog may be
>> called, and it will access sd->process_queue.
>>
>
> It should be okay?  process_backlog only runs in softirq so bottom
> halves are already disabled, and I don't think flush_backlog runs out
> of an interrupt.
>

Oh no. It is an IRQ handler.

  on_each_cpu(flush_backlog, dev, 1);
...
int on_each_cpu(void (*func) (void *info), void *info, int wait)
{
        int ret = 0;

        preempt_disable();
        ret = smp_call_function(func, info, wait);
        local_irq_disable();
        func(info);
        local_irq_enable();
        preempt_enable();
        return ret;
}

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