[PATCH bugfix 3.9] PCI: Don't try to disable Bus Master on disconnected PCI devices
bhelgaas at google.com
Wed Apr 3 12:15:09 EDT 2013
On Mon, Apr 1, 2013 at 2:00 AM, Konstantin Khlebnikov
<khlebnikov at openvz.org> wrote:
> 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.
Applied to for-linus for v3.9, thanks!
> Konstantin Khlebnikov wrote:
>> This is fix for commit 7897e6022761ace7377f0f784fca059da55f5d71 from
>> ("PCI: Disable Bus Master unconditionally in pci_device_shutdown()")
>> in turn that was fix for b566a22c23327f18ce941ffad0ca907e50a53d41 from
>> ("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
>> - pci_clear_master(pci_dev);
>> + if (pci_dev->current_state <= PCI_D3hot)
>> + pci_clear_master(pci_dev);
>> #ifdef CONFIG_PM
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