[PATCH bugfix 3.9] PCI: Don't try to disable Bus Master on disconnected PCI devices
khlebnikov at openvz.org
Mon Apr 1 04:00:01 EDT 2013
BUMP. This is degradation from 3.8, so this patch must be in 3.9.
I still don't like this forced clearing bus-master bit. But this hack
definitely fixes problems in kexec, so there is reason to keep it here.
Konstantin Khlebnikov wrote:
> This is fix for commit 7897e6022761ace7377f0f784fca059da55f5d71 from v3.9-rc1
> ("PCI: Disable Bus Master unconditionally in pci_device_shutdown()")
> in turn that was fix for b566a22c23327f18ce941ffad0ca907e50a53d41 from v3.5-rc1
> ("PCI: disable Bus Master on PCI device shutdown")
> Unfortunately fixing one bug uncovers another:
> ->shutdown() callback might switch device to deep sleep state.
> PCI config space no longer available after that.
> Link: https://lkml.org/lkml/2013/3/12/529
> Signed-off-by: Konstantin Khlebnikov<khlebnikov at openvz.org>
> Reported-and-Tested-by: Vivek Goyal<vgoyal at redhat.com>
> Cc: Bjorn Helgaas<bhelgaas at google.com>
> Cc: Rafael J. Wysocki<rafael.j.wysocki at intel.com>
> drivers/pci/pci-driver.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
> index 1fa1e48..79277fb 100644
> --- a/drivers/pci/pci-driver.c
> +++ b/drivers/pci/pci-driver.c
> @@ -390,9 +390,10 @@ static void pci_device_shutdown(struct device *dev)
> * Turn off Bus Master bit on the device to tell it to not
> - * continue to do DMA
> + * continue to do DMA. Don't touch devices in D3cold or unknown states.
> - pci_clear_master(pci_dev);
> + if (pci_dev->current_state <= PCI_D3hot)
> + pci_clear_master(pci_dev);
> #ifdef CONFIG_PM
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