netdev - Re: Realtek 8139 driver (8139too.c) TX Timeout doesn't allow interrupt handler to disable receive interrupts at high bi-directional traffic

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Date:	Wed, 29 Nov 2006 14:50:54 -0800
From:	Stephen Hemminger <shemminger@...l.org>
To:	Francois Romieu <romieu@...zoreil.com>
Cc:	"Basheer, Mansoor Ahamed" <mansoor.ahamed@...com>,
	netdev@...r.kernel.org
Subject: Re: Realtek 8139 driver (8139too.c) TX Timeout doesn't allow
 interrupt handler to disable receive interrupts at high bi-directional
 traffic

On Wed, 29 Nov 2006 23:44:00 +0100
Francois Romieu <romieu@...zoreil.com> wrote:

> Stephen Hemminger <shemminger@...l.org> :
> [...]
> > @@ -1682,12 +1685,11 @@ static void rtl8139_tx_timeout_task (voi
> >  	rtl8139_tx_clear (tp);
> >  	spin_unlock_irq(&tp->lock);
> >  
> > +	netif_poll_enable();
>                           ^ -> dev
> > +
> >  	/* ...and finally, reset everything */
> > -	if (netif_running(dev)) {
> > -		rtl8139_hw_start (dev);
> > -		netif_wake_queue (dev);
> > -	}
> > -	spin_unlock_bh(&tp->rx_lock);
> > +	rtl8139_hw_start (dev);
> > +	netif_wake_queue (dev);
> >  }
> 
> rtl8139_hw_start() may mess with cur_rx, whence a race with rtl8139_rx()
> if an in-flight interruption enables it a bit too fast. I'd rather go
> with:

but rt8139_rx is not possible here because we have blocked the poll
routine from starting.  Basically it uses the NAPI rx scheduler bit
to replace the rx_lock.

It is totally, untested.  

-- 
Stephen Hemminger <shemminger@...l.org>
-
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