Patch "PCI: hv: Lock PCI bus on device eject" has been added to the 4.9-stable tree

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;a=summary

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 <[email protected]> know about it.

From: Long Li <[email protected]>
Date: Thu, 23 Mar 2017 14:58:32 -0700
Subject: PCI: hv: Lock PCI bus on device eject

From: Long Li <[email protected]>

[ 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 <[email protected]> for pointing out the race condition in create_root_hv_pci_bus().

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

@@ -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 [email protected] are

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