From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: [PATCH 4/5] PCI: don't touch enable_cnt in pci_device_shutdown() To: linux-kernel@vger.kernel.org From: Konstantin Khlebnikov Cc: e1000-devel@lists.sourceforge.net, linux-pci@vger.kernel.org, Bjorn Helgaas , Khalid Aziz Date: Fri, 18 Jan 2013 15:42:26 +0400 Message-ID: <20130118114225.6698.42016.stgit@zurg> In-Reply-To: <20130118113019.6698.25941.stgit@zurg> References: <20130118113019.6698.25941.stgit@zurg> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: 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 Cc: linux-pci@vger.kernel.org Cc: Bjorn Helgaas Cc: Khalid Aziz --- 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