While enabling sriov for intel igb device got:
sca05-0a81fda5:~ # echo 7 > /sys/bus/pci/devices/0000\:09\:00.0/sriov_numvfs
[ 729.612191] pci 0000:0a:10.0: [8086:1520] type 00 class 0x020000
[ 729.619002] BUG: unable to handle kernel NULL pointer dereference at 00000000000000e8
[ 729.627767] IP: [<ffffffff815901cb>] pci_get_hp_params+0x5b/0x640
[ 729.634593] PGD 0
[ 729.636844] Oops: 0000 [#1] SMP
[ 729.640466] Modules linked in:
...
[ 729.795268] Call Trace:
[ 729.798007] [<ffffffff81ea0843>] ? pci_mmcfg_read+0x123/0x140
[ 729.804519] [<ffffffff81ea0770>] ? pci_mmcfg_read+0x50/0x140
[ 729.810942] [<ffffffff815692a3>] pci_configure_device+0x33/0x350
[ 729.817744] [<ffffffff8156aba4>] pci_device_add+0x24/0x160
[ 729.823965] [<ffffffff8158f3bb>] pci_enable_sriov+0x4db/0x7d0
[ 729.830486] [<ffffffff81b63f54>] ? igb_pci_enable_sriov+0xe4/0x200
[ 729.837481] [<ffffffff81b63f7f>] igb_pci_enable_sriov+0x10f/0x200
[ 729.844386] [<ffffffff8155129c>] ? _kstrtoull+0x2c/0x80
[ 729.850315] [<ffffffff81b640a5>] igb_pci_sriov_configure+0x35/0x40
[ 729.857318] [<ffffffff815752b5>] sriov_numvfs_store+0xe5/0x140
[ 729.863934] [<ffffffff817e1f88>] dev_attr_store+0x18/0x30
[ 729.870063] [<ffffffff812624d8>] sysfs_kf_write+0x48/0x60
[ 729.876186] [<ffffffff812617ef>] ? kernfs_fop_write+0xaf/0x170
[ 729.882797] [<ffffffff81261827>] kernfs_fop_write+0xe7/0x170
[ 729.889222] [<ffffffff811ef66b>] vfs_write+0xcb/0x1c0
[ 729.894958] [<ffffffff811f0019>] SyS_write+0x49/0xb0
...
[ 729.943531] ---[ end trace 7cf0cdb66637665a ]---
and pci_get_hp_params+0x5b point to
0xffffffff815901cb is in pci_get_hp_params (include/linux/device.h:815).
810 #include <linux/pm_wakeup.h>
811
812 static inline const char *dev_name(const struct device *dev)
813 {
814 /* Use the init name until the kobject becomes available */
815 if (dev->init_name)
816 return dev->init_name;
817
818 return kobject_name(&dev->kobj);
The root cause:
Now pci_configure_device/pci_get_hp_params will be called for every pci_dev,
including VF that is under virtual bus. But virtual bus does not have bridge
set. So we can not refer pbus->self->dev directly.
Add checking with pbus->slef and bail out early.
Fixing: commit 6cd33649fa83 ("PCI: Add pci_configure_device() during enumeration")
Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
---
include/linux/pci-acpi.h | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
Index: linux-2.6/include/linux/pci-acpi.h
===================================================================
--- linux-2.6.orig/include/linux/pci-acpi.h
+++ linux-2.6/include/linux/pci-acpi.h
@@ -44,8 +44,12 @@ static inline acpi_handle acpi_pci_get_b
if (pci_is_root_bus(pbus))
dev = pbus->bridge;
- else
+ else {
+ if (!pbus->self)
+ return NULL;
+
dev = &pbus->self->dev;
+ }
dev_printk(KERN_DEBUG, &pbus->dev, " bridge ACPI_HANDLE %p : %s\n",
ACPI_HANDLE(dev), dev_name(dev));
--
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