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Commit 8d3d50bf authored by Breno Leitao's avatar Breno Leitao Committed by Benjamin Herrenschmidt
Browse files

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: default avatarBreno Leitao <leitao@linux.vnet.ibm.com>
Signed-off-by: default avatarLinas Vepstas <linasvepstas@gmail.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent e0508b15

arch/powerpc/include/asm/ppc-pci.h

+5 −0
Original line number Diff line number Diff line
@@ -137,6 +137,11 @@ struct device_node * find_device_pe(struct device_node *dn); 
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 */

arch/powerpc/platforms/pseries/eeh.c

+2 −2
Original line number Diff line number Diff line
@@ -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();

arch/powerpc/platforms/pseries/eeh_driver.c

+2 −2
Original line number Diff line number Diff line
@@ -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);

	}

arch/powerpc/platforms/pseries/eeh_event.c

+1 −1
Original line number Diff line number Diff line
@@ -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);