This is a note to let you know that I've just added the patch titled

PCI: hv: Lock PCI bus on device eject

to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: pci-hv-lock-pci-bus-on-device-eject.patch and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Sun Mar 18 16:55:33 CET 2018

From: Long Li longli@microsoft.com Date: Thu, 23 Mar 2017 14:58:32 -0700 Subject: PCI: hv: Lock PCI bus on device eject

From: Long Li longli@microsoft.com

[ 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@microsoft.com for pointing out the race condition in create_root_hv_pci_bus().

Reported-by: Xiaofeng Wang xiaofwan@redhat.com Signed-off-by: Long Li longli@microsoft.com Signed-off-by: Bjorn Helgaas bhelgaas@google.com Acked-by: K. Y. Srinivasan kys@microsoft.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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));

Patches currently in stable-queue which might be from longli@microsoft.com are

queue-4.9/pci-hv-lock-pci-bus-on-device-eject.patch queue-4.9/pci-hv-properly-handle-pci-bus-remove.patch