On Monday 25 May 2009 06:08:03 pm Kenji Kaneshige wrote:
> Fix wrong struct pci_dev reference counter 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().
I don't like this ACPI/PCI bind thing in general because having the
extra .bind and .unbind methods is ugly and somewhat non-obvious, and
I'm nervous about object lifetime issues like this one.
But I don't have a better alternative to offer, and there's definitely
a problem here, so thanks for fixing and testing it. I do have one
question below about whether the comment in the existing code, which
seems to be an excuse for doing the hand-made pci_find_slot(), is
still relevant, or should just be removed.
Bjorn
> [ 206.427004] BUG: unable to handle kernel NULL pointer dereference at 00000000000000e8
> [ 206.427076] IP: [<ffffffff803f0e9b>] acpi_pci_unbind+0xb1/0xdd
> [ 206.427076] PGD 8225ad067 PUD 82258b067 PMD 0
> [ 206.427076] Oops: 0000 [#1] SMP
> [ 206.427076] last sysfs file: /sys/bus/pci/slots/1/power
> [ 206.427076] CPU 2
> [ 206.427076] Modules linked in: acpiphp ipv6 autofs4 hidp rfcomm l2cap bluetooth sunrpc dm_mirror dm_region_hash dm_log dm_multipath scsi_dh dm_mod sbs sbshc pci_slot battery ac parport_pc lp parport sg mptspi mptscsih mptbase scsi_transport_spi sr_mod cdrom e1000e serio_raw button i2c_i801 i2c_core shpchp pcspkr ata_piix libata megaraid_sas sd_mod scsi_mod crc_t10dif ext3 jbd uhci_hcd ohci_hcd ehci_hcd [last unloaded: microcode]
> [ 206.427076] Pid: 10367, comm: bash Not tainted 2.6.30-rc4-kk #10 PRIMERGY
> [ 206.427076] RIP: 0010:[<ffffffff803f0e9b>] [<ffffffff803f0e9b>] acpi_pci_unbind+0xb1/0xdd
> [ 206.427076] RSP: 0018:ffff8808225a9d68 EFLAGS: 00010206
> [ 206.427076] RAX: 0000000000000000 RBX: ffff88083c547800 RCX: 0000000000000006
> [ 206.427076] RDX: ffff88083ce36ca0 RSI: ffff880822508768 RDI: 0000000000000000
> [ 206.427076] RBP: ffff8808225a9d98 R08: 0000000000000000 R09: 0000000000000000
> [ 206.427076] R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000001
> [ 206.427076] R13: 0000000000000000 R14: 0000000000000001 R15: ffff8808225a9e28
> [ 206.427076] FS: 00007f376c4ee6e0(0000) GS:ffff880054636000(0000) knlGS:0000000000000000
> [ 206.427076] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> [ 206.427076] CR2: 00000000000000e8 CR3: 0000000822590000 CR4: 00000000000006e0
> [ 206.427076] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [ 206.427076] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> [ 206.427076] Process bash (pid: 10367, threadinfo ffff8808225a8000, task ffff880822508000)
> [ 206.427076] Stack:
> [ 206.427076] 000000000000001f ffff88083addd5a0 ffff8808225a9d98 ffff88083ce36ca0
> [ 206.427076] ffff88083c547800 ffff88083c547800 ffff8808225a9db8 ffffffff803ecee4
> [ 206.427076] ffff88083c547800 ffff88083c547000 ffff8808225a9e08 ffffffff803ecf6d
> [ 206.427076] Call Trace:
> [ 206.427076] [<ffffffff803ecee4>] acpi_bus_remove+0x54/0x68
> [ 206.427076] [<ffffffff803ecf6d>] acpi_bus_trim+0x75/0xe3
> [ 206.427076] [<ffffffffa0345ddd>] acpiphp_disable_slot+0x16d/0x1e0 [acpiphp]
> [ 206.427076] [<ffffffffa03441f0>] disable_slot+0x20/0x60 [acpiphp]
> [ 206.427076] [<ffffffff803cfc18>] power_write_file+0xc8/0x110
> [ 206.427076] [<ffffffff803c6a54>] pci_slot_attr_store+0x24/0x30
> [ 206.427076] [<ffffffff803469ce>] sysfs_write_file+0xce/0x140
> [ 206.427076] [<ffffffff802e94e7>] vfs_write+0xc7/0x170
> [ 206.427076] [<ffffffff802e9aa0>] sys_write+0x50/0x90
> [ 206.427076] [<ffffffff8020bd6b>] system_call_fastpath+0x16/0x1b
> [ 206.427076] Code: be 2b 01 00 00 48 c7 c7 d0 c6 5a 80 31 c0 e8 c3 8f 01 00 eb 36 48 8b 55 e8 48 8b 42 10 48 83 78 18 00 74 13 48 8b 42 08 0f b7 3a <0f> b6 b0 e8 00 00 00 e8 ab f8 ff ff 48 8b 7d e8 e8 30 cf ee ff
> [ 206.427076] RIP [<ffffffff803f0e9b>] acpi_pci_unbind+0xb1/0xdd
> [ 206.427076] RSP <ffff8808225a9d68>
> [ 206.427076] CR2: 00000000000000e8
> [ 206.440158] ---[ end trace 1ca3974fa717e665 ]---
>
> Signed-off-by: Kenji Kaneshige <kaneshige.kenji@xxxxxxxxxxxxxx>
>
> drivers/acpi/pci_bind.c | 21 ++++++---------------
> 1 file changed, 6 insertions(+), 15 deletions(-)
>
> Index: 20090521/drivers/acpi/pci_bind.c
> ===================================================================
> --- 20090521.orig/drivers/acpi/pci_bind.c
> +++ 20090521/drivers/acpi/pci_bind.c
> @@ -116,9 +116,6 @@ int acpi_pci_bind(struct acpi_device *de
> 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;
> @@ -180,16 +177,8 @@ int acpi_pci_bind(struct acpi_device *de
> * PCI devices are added to the global pci list when the root
> * bridge start ops are run, which may not have happened yet.
Please update or remove this comment, which claims that "we cannot
simply search the global pci device list." I don't know whether the
comment (a) explains why we can't use pci_get_slot(), (b) explains
why we can't use pci_find_slot() or some other interface, (c) refers
to an ordering problem that doesn't exist on your system, or (d) is
just no longer applicable at all.
> */
> - 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 +248,10 @@ int acpi_pci_bind(struct acpi_device *de
>
> end:
> kfree(buffer.pointer);
> - if (result)
> + if (result) {
> + pci_dev_put(data->dev);
> kfree(data);
> -
> + }
> return result;
> }
>
> @@ -303,6 +293,7 @@ static int acpi_pci_unbind(struct acpi_d
> if (data->dev->subordinate) {
> acpi_pci_irq_del_prt(data->id.segment, data->bus->number);
> }
> + pci_dev_put(data->dev);
> kfree(data);
>
> end:
--
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