Messages in this thread Patch in this message | | | Subject | [PATCH 4/5] PCI: don't touch enable_cnt in pci_device_shutdown() | From | Konstantin Khlebnikov <> | Date | Fri, 18 Jan 2013 15:42:26 +0400 |
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comment in commit b566a22c23327f18ce941ffad0ca907e50a53d41 ("PCI: disable Bus Master on PCI device shutdown") says:
| Disable Bus Master bit on the device in pci_device_shutdown() to ensure PCI | devices do not continue to DMA data after shutdown. This can cause memory | corruption in case of a kexec where the current kernel shuts down and | transfers control to a new kernel while a PCI device continues to DMA to | memory that does not belong to it any more in the new kernel.
Seems like pci_clear_master() must be used here instead of pci_disable_device(), because it disables Bus Muster unconditionally and doesn't changes enable_cnt.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: linux-pci@vger.kernel.org Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Khalid Aziz <khalid.aziz@hp.com> --- drivers/pci/pci-driver.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c index 030dbf0..853d605 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -392,7 +392,7 @@ 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 */ - pci_disable_device(pci_dev); + pci_clear_master(pci_dev); } #ifdef CONFIG_PM
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