4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Long Li <longli@xxxxxxxxxxxxx>
[ Upstream commit 414428c5da1c71986727c2fa5cdf1ed071e398d7 ]
A PCI_EJECT message can arrive at the same time we are calling
pci_scan_child_bus() in the workqueue for the previous PCI_BUS_RELATIONS
message or in create_root_hv_pci_bus(). In this case we could potentially
modify the bus from multiple places.
Properly lock the bus access.
Thanks Dexuan Cui <decui@xxxxxxxxxxxxx> for pointing out the race condition
in create_root_hv_pci_bus().
Reported-by: Xiaofeng Wang <xiaofwan@xxxxxxxxxx>
Signed-off-by: Long Li <longli@xxxxxxxxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Acked-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/pci/host/pci-hyperv.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -1206,9 +1206,11 @@ static int create_root_hv_pci_bus(struct
hbus->pci_bus->msi = &hbus->msi_chip;
hbus->pci_bus->msi->dev = &hbus->hdev->device;
+ pci_lock_rescan_remove();
pci_scan_child_bus(hbus->pci_bus);
pci_bus_assign_resources(hbus->pci_bus);
pci_bus_add_devices(hbus->pci_bus);
+ pci_unlock_rescan_remove();
hbus->state = hv_pcibus_installed;
return 0;
}
@@ -1597,8 +1599,10 @@ static void hv_eject_device_work(struct
pdev = pci_get_domain_bus_and_slot(hpdev->hbus->sysdata.domain, 0,
wslot);
if (pdev) {
+ pci_lock_rescan_remove();
pci_stop_and_remove_bus_device(pdev);
pci_dev_put(pdev);
+ pci_unlock_rescan_remove();
}
memset(&ctxt, 0, sizeof(ctxt));