Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753041Ab3HWBzX (ORCPT ); Thu, 22 Aug 2013 21:55:23 -0400 Received: from e28smtp08.in.ibm.com ([122.248.162.8]:59522 "EHLO e28smtp08.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752038Ab3HWBzW (ORCPT ); Thu, 22 Aug 2013 21:55:22 -0400 From: Wei Yang To: alex.williamson@redhat.com, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Cc: aik@ozlabs.ru, paulus@au1.ibm.com, benh@au1.ibm.com, Wei Yang Subject: [PATCH] iommu: WARN_ON when removing a device with no iommu_group associated Date: Fri, 23 Aug 2013 09:55:11 +0800 Message-Id: <1377222911-12144-1-git-send-email-weiyang@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.5.4 X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13082301-2000-0000-0000-00000D6CC83D Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1615 Lines: 40 When removing a device from the system, iommu_group driver will try to disconnect it from its group. While in some cases, one device may not associated with any iommu_group. For example, not enough DMA address space. In the generic bus notification, it will check dev->iommu_group before calling iommu_group_remove_device(). While in some cases, developers may call iommu_group_remove_device() in a different code path and without check. For those devices with dev->iommu_group set to NULL, kernel will crash. This patch gives a warning and return when trying to remove a device from an iommu_group with dev->iommu_group set to NULL. This helps to indicate some bad behavior and also guard the kernel. Signed-off-by: Wei Yang --- drivers/iommu/iommu.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index fbe9ca7..43396f0 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -379,6 +379,9 @@ void iommu_group_remove_device(struct device *dev) struct iommu_group *group = dev->iommu_group; struct iommu_device *tmp_device, *device = NULL; + if (WARN_ON(!group)) + return; + /* Pre-notify listeners that a device is being removed. */ blocking_notifier_call_chain(&group->notifier, IOMMU_GROUP_NOTIFY_DEL_DEVICE, dev); -- 1.7.5.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/