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.
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