Re: [PCI] BUG: unable to handle kernel

[Murali Karicheri]

On 03/06/2015 11:55 AM, Guenter Roeck wrote:
> On Fri, Mar 06, 2015 at 10:48:59AM -0500, Murali Karicheri wrote:
> [ ... ]
>
> > > From 098b4f5e4ab9407fbdbfcca3a91785c17e25cf03 Mon Sep 17 00:00:00 2001
> > From: Murali Karicheri<m-karicheri2@xxxxxx>
> > Date: Fri, 6 Mar 2015 10:23:08 -0500
> > Subject: [PATCH] pci: of : fix kernel crash
> >
> > This is a debug patch to root cause the kernel crash
> >
> > 	commit 0b2af171520e5d5e7d5b5f479b90a6a5014d9df6
> >
> > 	PCI: Update DMA configuration from DT
> >
> > Signed-off-by: Murali Karicheri<m-karicheri2@xxxxxx>
> > ---
> >   drivers/of/of_pci.c       |    8 ++++++++
> >   drivers/pci/host-bridge.c |    5 +++++
> >   2 files changed, 13 insertions(+)
> >
> > diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
> > index 86d3c38..5a59fb8 100644
> > --- a/drivers/of/of_pci.c
> > +++ b/drivers/of/of_pci.c
> > @@ -129,6 +129,14 @@ void of_pci_dma_configure(struct pci_dev *pci_dev)
> >   	struct device *dev =&pci_dev->dev;
> >   	struct device *bridge = pci_get_host_bridge_device(pci_dev);
> >
> > +	if (!bridge || !bridge->parent) {
> > +		if (!bridge)
> > +			pr_err("PCI bridge not found\n");
> > +		if (!bridge->parent)
> > +			pr_err("PCI bridge parent not found\n");
>
> You'll see a crash here if bridge is NULL. Maybe add an else before the second
> if statement ? Also, dev_err might be a bit more useful and would be available.
Fixed and attached.

Murali
> Thanks,
> Guenter
>
> > +		return;
> > +	}
> > +
> >   	of_dma_configure(dev, bridge->parent->of_node);
> >   	pci_put_host_bridge_device(bridge);
> >   }
> > diff --git a/drivers/pci/host-bridge.c b/drivers/pci/host-bridge.c
> > index 3e5bbf9..ef2ab51 100644
> > --- a/drivers/pci/host-bridge.c
> > +++ b/drivers/pci/host-bridge.c
> > @@ -28,6 +28,11 @@ struct device *pci_get_host_bridge_device(struct pci_dev *dev)
> >   	struct pci_bus *root_bus = find_pci_root_bus(dev->bus);
> >   	struct device *bridge = root_bus->bridge;
> >
> > +	if (!bridge) {
> > +		pr_err("PCI: bridge not found\n");
> > +		return NULL;
> > +	}
> > +
> >   	kobject_get(&bridge->kobj);
> >   	return bridge;
> >   }
> > --
> > 1.7.9.5


--
Murali Karicheri
Linux Kernel, Texas Instruments