netdev - Re: [PATCH 1/2] tg3: 5701 DMA corruption fix

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Date:	Fri, 18 Apr 2008 10:45:35 -0700
From:	"Michael Chan" <mchan@...adcom.com>
To:	"David Miller" <davem@...emloft.net>
cc:	mcarlson@...adcom.com, netdev <netdev@...r.kernel.org>,
	andy@...yhouse.net, tonyb@...ernetics.com
Subject: Re: [PATCH 1/2] tg3: 5701 DMA corruption fix

On Thu, 2008-04-17 at 23:26 -0700, David Miller wrote:
> From: "Matt Carlson" <mcarlson@...adcom.com>
> Date: Wed, 16 Apr 2008 15:27:41 -0700
> 
> > +		while (pci_id->vendor != 0) {
> > +			bridge = pci_get_device(pci_id->vendor,
> > +						pci_id->device,
> > +						bridge);
> > +			if (!bridge) {
> > +				pci_id++;
> > +				continue;
> > +			}
> > +			if (bridge->subordinate &&
> > +			    (bridge->subordinate->number <=
> > +			     tp->pdev->bus->number) &&
> > +			    (bridge->subordinate->subordinate >=
> > +			     tp->pdev->bus->number)) {
> > +				tp->tg3_flags3 |= TG3_FLG3_5701_DMA_BUG;
> > +				pci_dev_put(bridge);
> > +				break;
> > +			}
> > +		}
> > +	}
> 
> This code block will leak bridge device objects when the table
> comparison check fails.

Do you mean having undecremented reference count on the bridge when it
doesn't match?

I think it is ok, because when we call pci_get_device() next time, we'll
pass in the old bridge so that it can find the next one.  pci_get_device
() will automatically decrement the reference count on the old bridge.

> 
> Probably the best thing to do is seperate the boolean check
> from the other operations:
> 
> 	bool match = false;
>  ...
> 	if (bridge->subordinate &&
> 	    (bridge->subordinate->number <=
> 	     tp->pdev->bus->number) &&
> 	    (bridge->subordinate->subordinate >=
> 	     tp->pdev->bus->number))
> 		match = true;
> 
> 	pci_dev_put_bridge(bridge);
> 
> 	if (match) {
> 		tp->tg3_flags |= TG3_FLG3_5701_DMA_BUG;
> 		pci_dev_put(bridge);
> 	}
> 
> Please fix this up, and combine the version bump into this patch.
> 
> Thank you!
> 

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