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Quote:>      /* disable interrupts here is necessary!
>          * We need to ensure Rx/RxNobuf ints are disabled if in poll
>          * flag is set. If interrupt comes bw* netif_rx_complete
>          * and enable_rx_and_rxnobuf_ints, the following will happen:
>          *         netif_rx_complete --> clear RX_SCHED flag
>          *           -> ints(e.g. TxDone)
>          *                  speedo_interrupt
>          *                       if (netif_rx_schedule_prep(dev))
>          *                          disable_rx_and_rxnobuf_ints
>          *                  return
>          *           <-
>          *         enable_rx_and_rxnobuf_ints
>          *  then we will have Rx&RxNoBuf ints enable while in polling!
>          *  it may lead to endless interrupts and effective lockup of
>          *  the whole machine.
>          */
>         spin_lock_irqsave(&sp->lock,flags);
>         netif_rx_complete(dev);
>         enable_rx_and_rxnobuf_ints(dev);
>         spin_unlock_irqrestore(&sp->lock,flags);

You must ACK irq in interrupt handler in some way.
Tulip really does trick with deferring ack to poll routine,
but it pays for this _masking_ irq each interrupt instead, which also
drops irq line. See?

Alexey
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Quote:Zhang Fuxin writes:

 > will meet it,so it is listed here.
 >      /* disable interrupts here is necessary!
 >          * We need to ensure Rx/RxNobuf ints are disabled if in poll
 >          * flag is set. If interrupt comes bw* netif_rx_complete
 >          * and enable_rx_and_rxnobuf_ints, the following will happen:
 >          *         netif_rx_complete --> clear RX_SCHED flag
 >          *           -> ints(e.g. TxDone)
 >          *                  speedo_interrupt
 >          *                       if (netif_rx_schedule_prep(dev))
 >          *                          disable_rx_and_rxnobuf_ints
 >          *                  return
 >          *           <-
 >          *         enable_rx_and_rxnobuf_ints
 >          *  then we will have Rx&RxNoBuf ints enable while in polling!
 >          *  it may lead to endless interrupts and effective lockup of
 >          *  the whole machine.
 >          */
 >         spin_lock_irqsave(&sp->lock,flags);
 >         netif_rx_complete(dev);
 >         enable_rx_and_rxnobuf_ints(dev);
 >         spin_unlock_irqrestore(&sp->lock,flags);

 Thanks!

 Yes as far as I see this correct... and this race and others is mentioned
 in NAPI_HOWTO.txt and yes the spinlock can help for the drivers that uses
 this type interrupt acking. And tulip is a candidate for this as well. Let
 see if it solves Paul's problem to start with.

 Cheers.
                                                --ro

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Quote:>     By disabling irq in speedo_poll,we can be sure this won't happen.
...
>  could you find a flaw?

Alexey
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