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From: Greg KH on 11 Aug 2010 20:10
2.6.32-stable review patch. If anyone has any objections, please let us know.

------------------

From: Breno Leitao <leitao(a)linux.vnet.ibm.com>

commit 8d3d50bf1913561ef3b1f5b53115c5a481ba9b1e upstream.

During a EEH recover, the pci_dev structure can be null, mainly if an
eeh event is detected during cpi config operation. In this case, the
pci_dev will not be known (and will be null) the kernel will crash
with the following message:

Unable to handle kernel paging request for data at address 0x000000a0
Faulting instruction address: 0xc00000000006b8b4
Oops: Kernel access of bad area, sig: 11 [#1]

NIP [c00000000006b8b4] .eeh_event_handler+0x10c/0x1a0
LR [c00000000006b8a8] .eeh_event_handler+0x100/0x1a0
Call Trace:
[c0000003a80dff00] [c00000000006b8a8] .eeh_event_handler+0x100/0x1a0
[c0000003a80dff90] [c000000000031f1c] .kernel_thread+0x54/0x70

The bug occurs because pci_name() tries to access a null pointer.
This patch just guarantee that pci_name() is not called on Null pointers.

Signed-off-by: Breno Leitao <leitao(a)linux.vnet.ibm.com>
Signed-off-by: Linas Vepstas <linasvepstas(a)gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh(a)kernel.crashing.org>
Acked-by: Jeff Mahoney <jeffm(a)suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de>

---
arch/powerpc/include/asm/ppc-pci.h | 5 +++++
arch/powerpc/platforms/pseries/eeh.c | 4 ++--
arch/powerpc/platforms/pseries/eeh_driver.c | 4 ++--
arch/powerpc/platforms/pseries/eeh_event.c | 2 +-
4 files changed, 10 insertions(+), 5 deletions(-)

--- a/arch/powerpc/include/asm/ppc-pci.h
+++ b/arch/powerpc/include/asm/ppc-pci.h
@@ -137,6 +137,11 @@ struct device_node * find_device_pe(stru
void eeh_sysfs_add_device(struct pci_dev *pdev);
void eeh_sysfs_remove_device(struct pci_dev *pdev);

+static inline const char *eeh_pci_name(struct pci_dev *pdev)
+{
+ return pdev ? pci_name(pdev) : "<null>";
+}
+
#endif /* CONFIG_EEH */

#else /* CONFIG_PCI */
--- a/arch/powerpc/platforms/pseries/eeh.c
+++ b/arch/powerpc/platforms/pseries/eeh.c
@@ -491,7 +491,7 @@ int eeh_dn_check_failure(struct device_n
pdn->eeh_mode & EEH_MODE_NOCHECK) {
ignored_check++;
pr_debug("EEH: Ignored check (%x) for %s %s\n",
- pdn->eeh_mode, pci_name (dev), dn->full_name);
+ pdn->eeh_mode, eeh_pci_name(dev), dn->full_name);
return 0;
}

@@ -515,7 +515,7 @@ int eeh_dn_check_failure(struct device_n
printk (KERN_ERR "EEH: %d reads ignored for recovering device at "
"location=%s driver=%s pci addr=%s\n",
pdn->eeh_check_count, location,
- dev->driver->name, pci_name(dev));
+ dev->driver->name, eeh_pci_name(dev));
printk (KERN_ERR "EEH: Might be infinite loop in %s driver\n",
dev->driver->name);
dump_stack();
--- a/arch/powerpc/platforms/pseries/eeh_driver.c
+++ b/arch/powerpc/platforms/pseries/eeh_driver.c
@@ -353,7 +353,7 @@ struct pci_dn * handle_eeh_events (struc
location = location ? location : "unknown";
printk(KERN_ERR "EEH: Error: Cannot find partition endpoint "
"for location=%s pci addr=%s\n",
- location, pci_name(event->dev));
+ location, eeh_pci_name(event->dev));
return NULL;
}

@@ -384,7 +384,7 @@ struct pci_dn * handle_eeh_events (struc
pci_str = pci_name (frozen_pdn->pcidev);
drv_str = pcid_name (frozen_pdn->pcidev);
} else {
- pci_str = pci_name (event->dev);
+ pci_str = eeh_pci_name(event->dev);
drv_str = pcid_name (event->dev);
}

--- a/arch/powerpc/platforms/pseries/eeh_event.c
+++ b/arch/powerpc/platforms/pseries/eeh_event.c
@@ -80,7 +80,7 @@ static int eeh_event_handler(void * dumm
eeh_mark_slot(event->dn, EEH_MODE_RECOVERING);

printk(KERN_INFO "EEH: Detected PCI bus error on device %s\n",
- pci_name(event->dev));
+ eeh_pci_name(event->dev));

pdn = handle_eeh_events(event);



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