linux-kernel - Re: [PCI] BUG: unable to handle kernel

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Date:	Mon, 9 Mar 2015 10:17:47 -0400
From:	Murali Karicheri <m-karicheri2@...com>
To:	Guenter Roeck <linux@...ck-us.net>,
	Bjorn Helgaas <bhelgaas@...gle.com>
CC:	Fengguang Wu <fengguang.wu@...el.com>, LKP <lkp@...org>,
	<linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PCI] BUG: unable to handle kernel

On 03/06/2015 12:58 PM, Murali Karicheri wrote:
> 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@...com>
>>> 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@...com>
>>> ---
>>> 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
>>>
>>
>
BJorn,

Any chance of applying the attached debug patch to see if this fixes and 
provide some additional information on this BUG? Not sure who will pick 
this one and apply.

-- 
Murali Karicheri
Linux Kernel, Texas Instruments
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