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PCI Hotplug: acpiphp: don't store a pci_dev in acpiphp_func

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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>
This commit is contained in:
Alex Chiang 2009-05-21 16:21:15 -06:00 committed by Jesse Barnes
parent b3bad72e49
commit 9d911d7903
2 changed files with 26 additions and 38 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/pci/hotplug/acpiphp.h
View File

@ -129,7 +129,6 @@ struct acpiphp_func {
struct acpiphp_bridge *bridge; /* Ejectable PCI-to-PCI bridge */
struct list_head sibling;
struct pci_dev *pci_dev;
struct notifier_block nb;
acpi_handle handle;

63
drivers/pci/hotplug/acpiphp_glue.c
View File

@ -32,9 +32,6 @@
/*
* Lifetime rules for pci_dev:
* - The one in acpiphp_func has its refcount elevated by pci_get_slot()
* when the driver is loaded or when an insertion event occurs. It loses
* a refcount when its ejected or the driver unloads.
* - The one in acpiphp_bridge has its refcount elevated by pci_get_slot()
* when the bridge is scanned and it loses a refcount when the bridge
* is removed.
@ -130,6 +127,7 @@ register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
unsigned long long adr, sun;
int device, function, retval;
struct pci_bus *pbus = bridge->pci_bus;
struct pci_dev *pdev;
if (!acpi_pci_check_ejectable(pbus, handle) && !is_dock_device(handle))
return AE_OK;
@ -213,10 +211,10 @@ register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
newfunc->slot = slot;
list_add_tail(&newfunc->sibling, &slot->funcs);
/* associate corresponding pci_dev */
newfunc->pci_dev = pci_get_slot(pbus, PCI_DEVFN(device, function));
if (newfunc->pci_dev) {
pdev = pci_get_slot(pbus, PCI_DEVFN(device, function));
if (pdev) {
slot->flags |= (SLOT_ENABLED | SLOT_POWEREDON);
pci_dev_put(pdev);
}
if (is_dock_device(handle)) {
@ -617,7 +615,6 @@ static void cleanup_bridge(struct acpiphp_bridge *bridge)
if (ACPI_FAILURE(status))
err("failed to remove notify handler\n");
}
pci_dev_put(func->pci_dev);
list_del(list);
kfree(func);
}
@ -1101,22 +1098,24 @@ static int __ref enable_device(struct acpiphp_slot *slot)
pci_enable_bridges(bus);
pci_bus_add_devices(bus);
/* associate pci_dev to our representation */
list_for_each (l, &slot->funcs) {
func = list_entry(l, struct acpiphp_func, sibling);
func->pci_dev = pci_get_slot(bus, PCI_DEVFN(slot->device,
func->function));
if (!func->pci_dev)
dev = pci_get_slot(bus, PCI_DEVFN(slot->device,
func->function));
if (!dev)
continue;
if (func->pci_dev->hdr_type != PCI_HEADER_TYPE_BRIDGE &&
func->pci_dev->hdr_type != PCI_HEADER_TYPE_CARDBUS)
if (dev->hdr_type != PCI_HEADER_TYPE_BRIDGE &&
dev->hdr_type != PCI_HEADER_TYPE_CARDBUS) {
pci_dev_put(dev);
continue;
}
status = find_p2p_bridge(func->handle, (u32)1, bus, NULL);
if (ACPI_FAILURE(status))
warn("find_p2p_bridge failed (error code = 0x%x)\n",
status);
pci_dev_put(dev);
}
slot->flags |= SLOT_ENABLED;
@ -1142,17 +1141,14 @@ static void disable_bridges(struct pci_bus *bus)
*/
static int disable_device(struct acpiphp_slot *slot)
{
int retval = 0;
struct acpiphp_func *func;
struct list_head *l;
struct pci_dev *pdev;
/* is this slot already disabled? */
if (!(slot->flags & SLOT_ENABLED))
goto err_exit;
list_for_each (l, &slot->funcs) {
func = list_entry(l, struct acpiphp_func, sibling);
list_for_each_entry(func, &slot->funcs, sibling) {
if (func->bridge) {
/* cleanup p2p bridges under this P2P bridge */
cleanup_p2p_bridge(func->bridge->handle,
@ -1160,35 +1156,28 @@ static int disable_device(struct acpiphp_slot *slot)
func->bridge = NULL;
}
if (func->pci_dev) {
pci_stop_bus_device(func->pci_dev);
if (func->pci_dev->subordinate) {
disable_bridges(func->pci_dev->subordinate);
pci_disable_device(func->pci_dev);
pdev = pci_get_slot(slot->bridge->pci_bus,
PCI_DEVFN(slot->device, func->function));
if (pdev) {
pci_stop_bus_device(pdev);
if (pdev->subordinate) {
disable_bridges(pdev->subordinate);
pci_disable_device(pdev);
}
pci_remove_bus_device(pdev);
pci_dev_put(pdev);
}
}
list_for_each (l, &slot->funcs) {
func = list_entry(l, struct acpiphp_func, sibling);
list_for_each_entry(func, &slot->funcs, sibling) {
acpiphp_unconfigure_ioapics(func->handle);
acpiphp_bus_trim(func->handle);
/* try to remove anyway.
* acpiphp_bus_add might have been failed */
if (!func->pci_dev)
continue;
pci_remove_bus_device(func->pci_dev);
pci_dev_put(func->pci_dev);
func->pci_dev = NULL;
}
slot->flags &= (~SLOT_ENABLED);
err_exit:
return retval;
err_exit:
return 0;
}