Re: [PATCH] Updated 8139too with NAPI

[OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>]

Jeff Garzik <jgarzik@xxxxxxxxx> writes:

> I'd like to apply this to net-drivers-2.[45]-exp, but it doesn't apply
> cleanly.  Can you wait a bit, for my posting of those queues, and then
> resend?

Probably more tester/reviewer is always welcome, so I think it's good.


Stephen Hemminger <shemminger@xxxxxxxx> writes:

> +     /* Receive packets are processed by poll routine.
> +        If not running start it now. */
> +     if (status & RxAckBits){
> +             if (netif_rx_schedule_prep(dev)) {
> +                     RTL_W16_F (IntrMask, rtl8139_norx_intr_mask);
> +                     __netif_rx_schedule (dev);
>               }

I think that this style is common issues of NIC drivers for "NAPI
support and intr-mask" handling. Looks like __netif_poll_disable()
also has the following problem.

For example,

        in ISR
                [...]
                if (status & RxAckBits){
                        if (netif_rx_schedule_prep(dev)) {
                                RTL_W16_F (IntrMask, rtl8139_norx_intr_mask);
                                __netif_rx_schedule (dev);
                        }
                }
                [...]

        in dev_close()
                [...]
                while (test_bit(__LINK_STATE_RX_SCHED, &dev->state)) {
                        /* No hurry. */
                        current->state = TASK_INTERRUPTIBLE;
                        schedule_timeout(1);
                }
                  --------- (*)
                if (dev->stop)
                        dev->stop(dev);
                [...]

If Rx interrupt happen on (*) point, ISR can't ack or disable.
Then it will start busy Rx interrupt loop. So if this happen, it's
seriously problem on UP system.
-- 
OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>