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authorAlex Chiang <achiang@hp.com>2009-05-21 16:21:15 -0600
committerJesse Barnes <jbarnes@virtuousgeek.org>2009-05-27 02:04:24 -0700
commit9d911d7903926a65ef49ec671bacd86bcee5eb51 (patch)
treeb41ef12ea20ae6a040fe1373a958befa07d434db /block
parentb3bad72e494fb2ff0c81be4ca2ddb94adf6a47c2 (diff)
PCI Hotplug: acpiphp: don't store a pci_dev in acpiphp_func
An oops can occur if a user attempts to use both PCI logical hotplug and the ACPI physical hotplug driver (acpiphp) in this sequence, where $slot/address == $device. In other words, if acpiphp has claimed a PCI device, and that device is logically removed, then acpiphp may oops when it attempts to access it again. # echo 1 > /sys/bus/pci/devices/$device/remove # echo 0 > /sys/bus/pci/slots/$slot/power Unable to handle kernel NULL pointer dereference (address 0000000000000000) Call Trace: [<a000000100016390>] show_stack+0x50/0xa0 [<a000000100016c60>] show_regs+0x820/0x860 [<a00000010003b390>] die+0x190/0x2a0 [<a000000100066a40>] ia64_do_page_fault+0x8e0/0xa40 [<a00000010000c7a0>] ia64_native_leave_kernel+0x0/0x270 [<a0000001003b2660>] pci_remove_bus_device+0x120/0x260 [<a0000002060549f0>] acpiphp_disable_slot+0x410/0x540 [acpiphp] [<a0000002060505c0>] disable_slot+0xc0/0x120 [acpiphp] [<a0000002040d21c0>] power_write_file+0x1e0/0x2a0 [pci_hotplug] [<a0000001003bb820>] pci_slot_attr_store+0x60/0xa0 [<a000000100240f70>] sysfs_write_file+0x230/0x2c0 [<a000000100195750>] vfs_write+0x190/0x2e0 [<a0000001001961a0>] sys_write+0x80/0x100 [<a00000010000c600>] ia64_ret_from_syscall+0x0/0x20 [<a000000000010720>] __kernel_syscall_via_break+0x0/0x20 The root cause of this oops is that the logical remove ("echo 1 > /sys/bus/pci/devices/$device/remove") destroyed the pci_dev. The pci_dev struct itself wasn't deallocated because acpiphp kept a reference, but some of its fields became invalid. acpiphp doesn't have any real reason to keep a pointer to a pci_dev around. It can always derive it using pci_get_slot(). If a logical remove destroys the pci_dev, acpiphp won't find it and is thus prevented from causing mischief. Reviewed-by: Matthew Wilcox <willy@linux.intel.com> Reviewed-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com> Tested-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com> Reported-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com> Acked-by: Bjorn Helgaas <bjorn.helgaas@hp.com> Signed-off-by: Alex Chiang <achiang@hp.com> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
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