On 10/17/2011 10:16 AM, Bjorn Helgaas wrote:
On Sat, Oct 15, 2011 at 7:31 PM, Yinghai Lu<yinghai.lu@xxxxxxxxxx> wrote:
When hot remove pci express module, got
[ 5918.610127] pciehp 0000:80:02.2:pcie04: pcie_isr: intr_loc 1
[ 5918.615779] pciehp 0000:80:02.2:pcie04: Attention button interrupt received
[ 5918.622730] pciehp 0000:80:02.2:pcie04: Button pressed on Slot(3)
[ 5918.629002] pciehp 0000:80:02.2:pcie04: pciehp_get_power_status: SLOTCTRL a8 value read 1f9
[ 5918.637416] pciehp 0000:80:02.2:pcie04: PCI slot #3 - powering off due to button press.
[ 5918.647125] pciehp 0000:80:02.2:pcie04: pcie_isr: intr_loc 10
[ 5918.653039] pciehp 0000:80:02.2:pcie04: pciehp_green_led_blink: SLOTCTRL a8 write cmd 200
[ 5918.661229] pciehp 0000:80:02.2:pcie04: pciehp_set_attention_status: SLOTCTRL a8 write cmd c0
[ 5924.667627] pciehp 0000:80:02.2:pcie04: Disabling domain:bus:device=0000:b0:00
[ 5924.674909] pciehp 0000:80:02.2:pcie04: pciehp_get_power_status: SLOTCTRL a8 value read 2f9
[ 5924.683262] pciehp 0000:80:02.2:pcie04: pciehp_unconfigure_device: domain:bus:dev = 0000:b0:00
[ 5924.693976] libfcoe_device_notification: NETDEV_UNREGISTER eth6
[ 5924.764979] libfcoe_device_notification: NETDEV_UNREGISTER eth14
[ 5924.873539] libfcoe_device_notification: NETDEV_UNREGISTER eth15
[ 5924.995209] libfcoe_device_notification: NETDEV_UNREGISTER eth16
[ 5926.114407] sxge 0000:b2:00.0: PCI INT A disabled
[ 5926.119342] BUG: unable to handle kernel NULL pointer dereference at (null)
[ 5926.127189] IP: [<ffffffff81353a3b>] pci_stop_bus_device+0x33/0x83
[ 5926.133377] PGD 0
[ 5926.135402] Oops: 0000 [#1] SMP
[ 5926.138659] CPU 2
[ 5926.140499] Modules linked in:
...
[ 5926.143754]
[ 5926.275823] Call Trace:
[ 5926.278267] [<ffffffff81353a38>] pci_stop_bus_device+0x30/0x83
[ 5926.284180] [<ffffffff81353af4>] pci_remove_bus_device+0x1a/0xba
[ 5926.290264] [<ffffffff81366311>] pciehp_unconfigure_device+0x110/0x17b
[ 5926.296866] [<ffffffff81365dd9>] ? pciehp_disable_slot+0x188/0x188
[ 5926.303123] [<ffffffff81365d6f>] pciehp_disable_slot+0x11e/0x188
[ 5926.309206] [<ffffffff81365e68>] pciehp_power_thread+0x8f/0xe0
...
Root cause: when doing pci_stop_bus_device() with phys fn, it will stop virt fn and
remove the fn, so
list_for_each_safe(l, n,&bus->devices)
will have problem to refer freed n that is pointed to vf entry.
Solution is just call pci_stop_bus_device() with phys fn only. and before that need to
save phys fn aside and avoid to use bus->devices to loop.
Signed-off-by: Yinghai Lu<yinghai@xxxxxxxxxx>
---
drivers/pci/remove.c | 33 +++++++++++++++++++++++++++++++++
1 file changed, 33 insertions(+)
Index: linux-2.6/drivers/pci/remove.c
===================================================================
--- linux-2.6.orig/drivers/pci/remove.c
+++ linux-2.6/drivers/pci/remove.c
@@ -120,10 +120,43 @@ void pci_remove_behind_bridge(struct pci
pci_remove_bus_device(pci_dev_b(l));
}
+struct dev_list {
+ struct pci_dev *dev;
+ struct list_head list;
+};
+
static void pci_stop_bus_devices(struct pci_bus *bus)
{
struct list_head *l, *n;
+ struct dev_list *dl, *dn;
+ LIST_HEAD(physfn_list);
+
+ /* Save phys_fn aside at first */
+ list_for_each(l,&bus->devices) {
+ struct pci_dev *dev = pci_dev_b(l);
+
+ if (!dev->is_virtfn) {
+ dl = kmalloc(sizeof(*dl), GFP_KERNEL);
+ if (!dl)
+ continue;
+ dl->dev = dev;
+ list_add_tail(&dl->list,&physfn_list);
+ }
+ }
+
+ /*
+ * stop bus device for phys_fn at first
+ * it will stop and remove vf in driver remove action
+ */
+ list_for_each_entry_safe(dl, dn,&physfn_list, list) {
+ struct pci_dev *dev = dl->dev;
+
+ pci_stop_bus_device(dev);
+
+ kfree(dl);
+ }
+ /* Do it again for left over in case */
list_for_each_safe(l, n,&bus->devices) {
struct pci_dev *dev = pci_dev_b(l);
pci_stop_bus_device(dev);
Apparently it's a problem to stop a VF before its PF? Why is that?
Sounds like there's an important dependency here, but I can't figure
it out. I would have naively expected that you would *want* to stop a
VF first, since it depends on the PF.
when you stop the VF, that VF will not be removed.
when you stop the PF, the driver will be unloaded, it will *STOP* the VF
at first and *REMOVE* the VF there. So the bus->devices will be touch at
that time.
for example when you have three VFs. those VFs will be removed from
bus->devices, and n in the list_for_each_safe will have invalid pointer
to freed entry.
So stop the VF at first will *NOT* help.
Thanks
Yinghai
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