[PATCH 1/2] eeh: Fixing a bug when pci structure is null

leitao at linux.vnet.ibm.com leitao at linux.vnet.ibm.com
Thu Jan 28 05:43:04 EST 2010


During a EEH recover, the pci_dev structure can be null, and currently
the kernel is crashing when pci_dev is null, 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 at linux.vnet.ibm.com>
Signed-off-by: Linas Vepstas <linasvepstas at gmail.com>
---
 arch/powerpc/include/asm/eeh.h              |    1 +
 arch/powerpc/platforms/pseries/eeh.c        |    4 ++--
 arch/powerpc/platforms/pseries/eeh_driver.c |   11 +++++++++--
 arch/powerpc/platforms/pseries/eeh_event.c  |    2 +-
 4 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/include/asm/eeh.h b/arch/powerpc/include/asm/eeh.h
index 66ea9b8..f860f56 100644
--- a/arch/powerpc/include/asm/eeh.h
+++ b/arch/powerpc/include/asm/eeh.h
@@ -49,6 +49,7 @@ unsigned long eeh_check_failure(const volatile void __iomem *token,
 				unsigned long val);
 int eeh_dn_check_failure(struct device_node *dn, struct pci_dev *dev);
 void __init pci_addr_cache_build(void);
+const char *eeh_pci_name(struct pci_dev *pdev);
 
 /**
  * eeh_add_device_early
diff --git a/arch/powerpc/platforms/pseries/eeh.c b/arch/powerpc/platforms/pseries/eeh.c
index ccd8dd0..f9360fe 100644
--- 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_node *dn, struct pci_dev *dev)
 	    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_node *dn, struct pci_dev *dev)
 			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();
diff --git a/arch/powerpc/platforms/pseries/eeh_driver.c b/arch/powerpc/platforms/pseries/eeh_driver.c
index ef8e454..afdddf6 100644
--- a/arch/powerpc/platforms/pseries/eeh_driver.c
+++ b/arch/powerpc/platforms/pseries/eeh_driver.c
@@ -41,6 +41,13 @@ static inline const char * pcid_name (struct pci_dev *pdev)
 	return "";
 }
 
+inline const char *eeh_pci_name(struct pci_dev *pdev)
+{
+        if (NULL==pdev)
+                return "<null>";
+        return pci_name(pdev);
+}
+
 #if 0
 static void print_device_node_tree(struct pci_dn *pdn, int dent)
 {
@@ -337,7 +344,7 @@ struct pci_dn * handle_eeh_events (struct eeh_event *event)
 		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;
 	}
 
@@ -368,7 +375,7 @@ struct pci_dn * handle_eeh_events (struct eeh_event *event)
 		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);
 	}
 	
diff --git a/arch/powerpc/platforms/pseries/eeh_event.c b/arch/powerpc/platforms/pseries/eeh_event.c
index ddb80f5..ec5df8f 100644
--- 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 * dummy)
 	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);
 
-- 
1.6.0.2



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