[PATCH 4.9 111/223] PCI: hv: Delete the device earlier from hbus->children for hot-remove

Greg Kroah-Hartman
2019-08-02T09:45:00Z

From: Dexuan Cui <decui@microsoft.com>

commit e74d2ebdda33b3bdd1826b5b92e9aa45bdf92bb3 upstream.

After we send a PCI_EJECTION_COMPLETE message to the host, the host will
immediately send us a PCI_BUS_RELATIONS message with
relations->device_count == 0, so pci_devices_present_work(), running on
another thread, can find the being-ejected device, mark the
hpdev->reported_missing to true, and run list_move_tail()/list_del() for
the device -- this races hv_eject_device_work() -> list_del().

Move the list_del() in hv_eject_device_work() to an earlier place, i.e.,
before we send PCI_EJECTION_COMPLETE, so later the
pci_devices_present_work() can't see the device.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jake Oshins <jakeo@microsoft.com>
Acked-by: K. Y. Srinivasan <kys@microsoft.com>
CC: Haiyang Zhang <haiyangz@microsoft.com>
CC: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/pci/host/pci-hyperv.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -1607,6 +1607,10 @@ static void hv_eject_device_work(struct
pci_unlock_rescan_remove();
}

+ spin_lock_irqsave(&hpdev->hbus->device_list_lock, flags);
+ list_del(&hpdev->list_entry);
+ spin_unlock_irqrestore(&hpdev->hbus->device_list_lock, flags);
+
memset(&ctxt, 0, sizeof(ctxt));
ejct_pkt = (struct pci_eject_response *)&ctxt.pkt.message;
ejct_pkt->message_type.type = PCI_EJECTION_COMPLETE;
@@ -1615,10 +1619,6 @@ static void hv_eject_device_work(struct
sizeof(*ejct_pkt), (unsigned long)&ctxt.pkt,
VM_PKT_DATA_INBAND, 0);

- spin_lock_irqsave(&hpdev->hbus->device_list_lock, flags);
- list_del(&hpdev->list_entry);
- spin_unlock_irqrestore(&hpdev->hbus->device_list_lock, flags);
-
put_pcichild(hpdev, hv_pcidev_ref_childlist);
put_pcichild(hpdev, hv_pcidev_ref_initial);
put_pcichild(hpdev, hv_pcidev_ref_pnp);