From 1e38b7140185e384da216aff66a711df09b5afc9 Mon Sep 17 00:00:00 2001 From: Gavin Shan Date: Mon, 17 Sep 2012 04:34:28 +0000 Subject: [PATCH] powerpc/eeh: Fix crash on converting OF node to edev The kernel crash was reported by Alexy. He was testing some feature with private kernel, in which Alexy added some code in pci_pm_reset() to read the CSR after writting it. The bug could be reproduced on Fiber Channel card (Fibre Channel: Emulex Corporation Saturn-X: LightPulse Fibre Channel Host Adapter (rev 03)) by the following commands. # echo 1 > /sys/devices/pci0004:01/0004:01:00.0/reset # rmmod lpfc # modprobe lpfc The history behind the test case is that those additional config space reading operations in pci_pm_reset() would cause EEH error, but we didn't detect EEH error until "modprobe lpfc". For the case, all the PCI devices on PCI bus (0004:01) were removed and added after PE reset. Then the EEH devices would be figured out again based on the OF nodes. Unfortunately, there were some child OF nodes under PCI device (0004:01:00.0), but they didn't have attached PCI_DN since they're invisible from PCI domain. However, we were still trying to convert OF node to EEH device without checking on the attached PCI_DN. Eventually, it caused the kernel crash as follows: Unable to handle kernel paging request for data at address 0x00000030 Faulting instruction address: 0xc00000000004d888 cpu 0x0: Vector: 300 (Data Access) at [c000000fc797b950] pc: c00000000004d888: .eeh_add_device_tree_early+0x78/0x140 lr: c00000000004d880: .eeh_add_device_tree_early+0x70/0x140 sp: c000000fc797bbd0 msr: 8000000000009032 dar: 30 dsisr: 40000000 current = 0xc000000fc78d9f70 paca = 0xc00000000edb0000 softe: 0 irq_happened: 0x00 pid = 2951, comm = eehd enter ? for help [c000000fc797bc50] c00000000004d848 .eeh_add_device_tree_early+0x38/0x140 [c000000fc797bcd0] c00000000004d848 .eeh_add_device_tree_early+0x38/0x140 [c000000fc797bd50] c000000000051b54 .pcibios_add_pci_devices+0x34/0x190 [c000000fc797bde0] c00000000004fb10 .eeh_reset_device+0x100/0x160 [c000000fc797be70] c0000000000502dc .eeh_handle_event+0x19c/0x300 [c000000fc797bf00] c000000000050570 .eeh_event_handler+0x130/0x1a0 [c000000fc797bf90] c000000000020138 .kernel_thread+0x54/0x70 The patch changes of_node_to_eeh_dev() and just returns NULL if the passed OF node doesn't have attached PCI_DN. Cc: stable@vger.kernel.org Reported-by: Alexey Kardashevskiy Signed-off-by: Gavin Shan Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/include/asm/pci-bridge.h | 8 ++++++++ arch/powerpc/platforms/pseries/eeh.c | 2 +- 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/include/asm/pci-bridge.h b/arch/powerpc/include/asm/pci-bridge.h index a059cb94952b..025a130729bc 100644 --- a/arch/powerpc/include/asm/pci-bridge.h +++ b/arch/powerpc/include/asm/pci-bridge.h @@ -182,6 +182,14 @@ static inline int pci_device_from_OF_node(struct device_node *np, #if defined(CONFIG_EEH) static inline struct eeh_dev *of_node_to_eeh_dev(struct device_node *dn) { + /* + * For those OF nodes whose parent isn't PCI bridge, they + * don't have PCI_DN actually. So we have to skip them for + * any EEH operations. + */ + if (!dn || !PCI_DN(dn)) + return NULL; + return PCI_DN(dn)->edev; } #else diff --git a/arch/powerpc/platforms/pseries/eeh.c b/arch/powerpc/platforms/pseries/eeh.c index 43f6ed415564..9a04322b1736 100644 --- a/arch/powerpc/platforms/pseries/eeh.c +++ b/arch/powerpc/platforms/pseries/eeh.c @@ -728,7 +728,7 @@ static void eeh_add_device_early(struct device_node *dn) { struct pci_controller *phb; - if (!dn || !of_node_to_eeh_dev(dn)) + if (!of_node_to_eeh_dev(dn)) return; phb = of_node_to_eeh_dev(dn)->phb;