powerpc/eeh: Fix a bug when pci structure is null

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@linux.vnet.ibm.com>
Signed-off-by: Linas Vepstas <linasvepstas@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

3 files changed, 5 insertions, 5 deletions

diff --git a/arch/powerpc/platforms/pseries/eeh.c b/arch/powerpc/platforms/pseries/eeh.c
index ccd8dd03b8c9..3304f32fc7b8 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 0c252c3a5f9f..b8d70f5d9aa9 100644
--- a/arch/powerpc/platforms/pseries/eeh_driver.c
+++ b/arch/powerpc/platforms/pseries/eeh_driver.c
@@ -337,7 +337,7 @@ 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 +368,7 @@ 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 ddb80f5d850b..ec5df8f519c7 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);