Re: [PATCH] PCI/ACPI: fix wrong ref count handling in acpi_pci_bind()

Kenji Kaneshige
2009-05-28T00:09:38Z

Thank you for updating the patch.
It looks good to me.

Thanks,
Kenji Kaneshige

Len Brown wrote:
>>From dacd2549ca61ddbdd1ed62a76ca95dea3f0e02c6 Mon Sep 17 00:00:00 2001
> From: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
> Date: Tue, 26 May 2009 09:08:03 +0900
> Subject: [PATCH] PCI/ACPI: fix wrong ref count handling in acpi_pci_bind()
>
> The 'dev' field of struct acpi_pci_data is having a pointer to struct
> pci_dev without incrementing the reference counter. Because of this, I
> got the following kernel oops when I was doing some pci hotplug
> operations. This patch fixes this bug by replacing wrong hand-made
> pci_find_slot() with pci_get_slot() in acpi_pci_bind().
>
> BUG: unable to handle kernel NULL pointer dereference at 00000000000000e8
> IP: [<ffffffff803f0e9b>] acpi_pci_unbind+0xb1/0xdd
>
> Call Trace:
> [<ffffffff803ecee4>] acpi_bus_remove+0x54/0x68
> [<ffffffff803ecf6d>] acpi_bus_trim+0x75/0xe3
> [<ffffffffa0345ddd>] acpiphp_disable_slot+0x16d/0x1e0 [acpiphp]
> [<ffffffffa03441f0>] disable_slot+0x20/0x60 [acpiphp]
> [<ffffffff803cfc18>] power_write_file+0xc8/0x110
> [<ffffffff803c6a54>] pci_slot_attr_store+0x24/0x30
> [<ffffffff803469ce>] sysfs_write_file+0xce/0x140
> [<ffffffff802e94e7>] vfs_write+0xc7/0x170
> [<ffffffff802e9aa0>] sys_write+0x50/0x90
> [<ffffffff8020bd6b>] system_call_fastpath+0x16/0x1b
>
> Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
> Reviewed-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
> Reviewed-by: Alex Chiang <achiang@hp.com>
> Tested-by: Alex Chiang <achiang@hp.com>
> Signed-off-by: Len Brown <len.brown@intel.com>
> ---
>
> as applied to the acpi tree...
>
> cheers,
> -Len
>
> drivers/acpi/pci_bind.c | 24 ++++++------------------
> 1 files changed, 6 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/acpi/pci_bind.c b/drivers/acpi/pci_bind.c
> index 95650f8..bc46de3 100644
> --- a/drivers/acpi/pci_bind.c
> +++ b/drivers/acpi/pci_bind.c
> @@ -116,9 +116,6 @@ int acpi_pci_bind(struct acpi_device *device)
> struct acpi_pci_data *pdata;
> struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
> acpi_handle handle;
> - struct pci_dev *dev;
> - struct pci_bus *bus;
> -
>
> if (!device || !device->parent)
> return -EINVAL;
> @@ -176,20 +173,9 @@ int acpi_pci_bind(struct acpi_device *device)
> * Locate matching device in PCI namespace. If it doesn't exist
> * this typically means that the device isn't currently inserted
> * (e.g. docking station, port replicator, etc.).
> - * We cannot simply search the global pci device list, since
> - * PCI devices are added to the global pci list when the root
> - * bridge start ops are run, which may not have happened yet.
> */
> - bus = pci_find_bus(data->id.segment, data->id.bus);
> - if (bus) {
> - list_for_each_entry(dev, &bus->devices, bus_list) {
> - if (dev->devfn == PCI_DEVFN(data->id.device,
> - data->id.function)) {
> - data->dev = dev;
> - break;
> - }
> - }
> - }
> + data->dev = pci_get_slot(pdata->bus,
> + PCI_DEVFN(data->id.device, data->id.function));
> if (!data->dev) {
> ACPI_DEBUG_PRINT((ACPI_DB_INFO,
> "Device %04x:%02x:%02x.%d not present in PCI namespace\n",
> @@ -259,9 +245,10 @@ int acpi_pci_bind(struct acpi_device *device)
>
> end:
> kfree(buffer.pointer);
> - if (result)
> + if (result) {
> + pci_dev_put(data->dev);
> kfree(data);
> -
> + }
> return result;
> }
>
> @@ -303,6 +290,7 @@ static int acpi_pci_unbind(struct acpi_device *device)
> if (data->dev->subordinate) {
> acpi_pci_irq_del_prt(data->id.segment, data->bus->number);
> }
> + pci_dev_put(data->dev);
> kfree(data);
>