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 <aik@ozlabs.ru> Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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@ -182,6 +182,14 @@ static inline int pci_device_from_OF_node(struct device_node *np,
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#if defined(CONFIG_EEH)
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#if defined(CONFIG_EEH)
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static inline struct eeh_dev *of_node_to_eeh_dev(struct device_node *dn)
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static inline struct eeh_dev *of_node_to_eeh_dev(struct device_node *dn)
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{
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{
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/*
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* For those OF nodes whose parent isn't PCI bridge, they
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* don't have PCI_DN actually. So we have to skip them for
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* any EEH operations.
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*/
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if (!dn || !PCI_DN(dn))
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return NULL;
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return PCI_DN(dn)->edev;
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return PCI_DN(dn)->edev;
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}
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}
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#else
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#else
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@ -728,7 +728,7 @@ static void eeh_add_device_early(struct device_node *dn)
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{
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{
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struct pci_controller *phb;
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struct pci_controller *phb;
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if (!dn || !of_node_to_eeh_dev(dn))
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if (!of_node_to_eeh_dev(dn))
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return;
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return;
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phb = of_node_to_eeh_dev(dn)->phb;
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phb = of_node_to_eeh_dev(dn)->phb;
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