PCI: hv: Fix a race condition when removing the device

[ Upstream commit 94d22763207ac6633612b8d8e0ca4fba0f7aa139 ]

On removing the device, any work item (hv_pci_devices_present() or
hv_pci_eject_device()) scheduled on workqueue hbus->wq may still be running
and race with hv_pci_remove().

This can happen because the host may send PCI_EJECT or PCI_BUS_RELATIONS(2)
and decide to rescind the channel immediately after that.

Fix this by flushing/destroying the workqueue of hbus before doing hbus remove.

Link: https://lore.kernel.org/r/1620806800-30983-1-git-send-email-longli@linuxonhyperv.com
Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
1 file changed