PCI: Disable Bus Master unconditionally in pci_device_shutdown()
Commit b566a22c ("PCI: disable Bus Master on PCI device shutdown") used pci_disable_device(), but that doesn't disable Bus Mastering unconditionally; we allow nested enable/disable calls, and only the last disable call actually does anything. This uses pci_clear_master() to unconditionally clear the Bus Master bit. Matthew Garrett and Alan Cox said (see LKML link below) that clearing Bus Master for all PCI devices may lead to unpredictable consequences: some devices ignores this bit and continue DMA, some of them hang after that or crash the whole system. But we're already trying to clear Bus Master in general because of b566a22c; this merely deals with the cases where drivers haven't shut down the device correctly. [bhelgaas: changelog] Link: https://lkml.org/lkml/2012/6/6/278Signed-off-by:Konstantin Khlebnikov <khlebnikov@openvz.org> Signed-off-by:
Bjorn Helgaas <bhelgaas@google.com> Acked-by:
Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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