Subject: Re: [RFT PATCH] 8139cp: properly support change of MTU values [v2]

From: John Greene <[email-masked]>
Date: Thu, 13 Dec 2012 14:56:41 -0500

On 12/03/2012 03:46 PM, Francois Romieu wrote:
> David Miller <[email-masked]> :
> [...]
>> I've applied this to net-next, if it triggers any problems we have
>> some time to work it out before 3.8 is released.
>
> I have bounced the messages to David Woodhouse since he authored the
> last 8139cp changes in net-next and owns the hardware to notice
> regressions.
>
> My message of two days ago was wrong : it is not possible for the irq
> handler to process a Tx event after the rings have been freed. Things
> still look racy wrt netpoll though.
>
> Any objection against the patch below ?
>
> (I did not gotoize the dev == NULL test: it is really unlikely and
> should go away).
>
> diff --git a/drivers/net/ethernet/realtek/8139cp.c b/drivers/net/ethernet/realtek/8139cp.c
> index 0da3f5e..57cd542 100644
> --- a/drivers/net/ethernet/realtek/8139cp.c
> +++ b/drivers/net/ethernet/realtek/8139cp.c
> @@ -577,28 +577,30 @@ static irqreturn_t cp_interrupt (int irq, void *dev_instance)
>   {
>   	struct net_device *dev = dev_instance;
>   	struct cp_private *cp;
> +	int handled = 0;
>   	u16 status;
>
>   	if (unlikely(dev == NULL))
>   		return IRQ_NONE;
>   	cp = netdev_priv(dev);
>
> +	spin_lock(&cp->lock);
> +
>   	status = cpr16(IntrStatus);
>   	if (!status || (status == 0xFFFF))
> -		return IRQ_NONE;
> +		goto out_unlock;
> +
> +	handled = 1;
>
>   	netif_dbg(cp, intr, dev, "intr, status %04x cmd %02x cpcmd %04x\n",
>   		  status, cpr8(Cmd), cpr16(CpCmd));
>
>   	cpw16(IntrStatus, status & ~cp_rx_intr_mask);
>
> -	spin_lock(&cp->lock);
> -
>   	/* close possible race's with dev_close */
>   	if (unlikely(!netif_running(dev))) {
>   		cpw16(IntrMask, 0);
> -		spin_unlock(&cp->lock);
> -		return IRQ_HANDLED;
> +		goto out_unlock;
>   	}
>
>   	if (status & (RxOK | RxErr | RxEmpty | RxFIFOOvr))
> @@ -612,8 +614,6 @@ static irqreturn_t cp_interrupt (int irq, void *dev_instance)
>   	if (status & LinkChg)
>   		mii_check_media(&cp->mii_if, netif_msg_link(cp), false);
>
> -	spin_unlock(&cp->lock);
> -
>   	if (status & PciErr) {
>   		u16 pci_status;
>
> @@ -625,7 +625,10 @@ static irqreturn_t cp_interrupt (int irq, void *dev_instance)
>   		/* TODO: reset hardware */
>   	}
>
> -	return IRQ_HANDLED;
> +out_unlock:
> +	spin_unlock(&cp->lock);
> +
> +	return IRQ_RETVAL(handled);
>   }
>
>   #ifdef CONFIG_NET_POLL_CONTROLLER
> --
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Francois,

Have incorporated this and test it on virtual hardware with on top of
  cb64edb6b89491edfdbae52ba7db9a8b8391d339 (my original work now 
upstream).  I plan to submit your work herein upstream as well, with 
attribution to you, if that's ok?

-- 
John Greene
[email-masked]