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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Message-ID: <20061129224400.GC18057@electric-eye.fr.zoreil.com>
Date:	Wed, 29 Nov 2006 23:44:00 +0100
From:	Francois Romieu <romieu@...zoreil.com>
To:	Stephen Hemminger <shemminger@...l.org>
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

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:
[...]

	rtl8139_tx_clear (tp);

	rtl8139_hw_start (dev);
	netif_wake_queue (dev);
   
	netif_poll_enable(dev);
	spin_unlock_irq(&tp->lock);
}

Otherwise the patch is cool.

-- 
Ueimor
-
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