netdev - Re: [net PATCH v2] 8139cp: Add dma_mapping

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Message-ID: <20130726212403.GA25674@electric-eye.fr.zoreil.com>
Date:	Fri, 26 Jul 2013 23:24:03 +0200
From:	Francois Romieu <romieu@...zoreil.com>
To:	Neil Horman <nhorman@...driver.com>
Cc:	netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>
Subject: Re: [net PATCH v2] 8139cp: Add dma_mapping_error checking

Neil Horman <nhorman@...driver.com> :
> On Fri, Jul 26, 2013 at 10:06:30PM +0200, Francois Romieu wrote:
> > Neil Horman <nhorman@...driver.com> :
[...]
> > > @@ -533,6 +533,11 @@ rx_status_loop:
> > >  
> > >  		mapping = dma_map_single(&cp->pdev->dev, new_skb->data, buflen,
> > >  					 PCI_DMA_FROMDEVICE);
> > > +		if (dma_mapping_error(&cp->pdev->dev, mapping)) {
> > > +			kfree_skb(skb);
> > 
> > 			dev->stats.rx_dropped++;
> > 
> > Sorry, I did not notice that skb contained newly received data :o/
> > 
> Yeah, this isn't needed.  The skb being mapped in is newly allocated, and
> contains no data.  We haven't dropped anything here, so theres no need for the
> stats bump.

Huh ?

[...error path...]
		kfree(skb);
[...normal path...]
	cp_rx_skb(cp, skb, desc);

Afaiks it's the same skb. We drop data and a stats bump is needed.

[...]
> Thoughts?

Nevermind. cp_start_xmit is a piece of it and it isn't your work to
turn it into something sensible.

-- 
Ueimor
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