Re: [PCI] BUG: unable to handle kernel

From: Murali Karicheri
Date: Fri Mar 06 2015 - 12:58:17 EST


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