* [PATCH] iommu: WARN_ON when removing a device with no iommu_group associated
@ 2013-08-23 1:55 Wei Yang
2013-08-23 3:33 ` Alex Williamson
0 siblings, 1 reply; 3+ messages in thread
From: Wei Yang @ 2013-08-23 1:55 UTC (permalink / raw)
To: alex.williamson, linux-kernel, linuxppc-dev; +Cc: aik, paulus, benh, Wei Yang
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 <weiyang@linux.vnet.ibm.com>
---
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
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] iommu: WARN_ON when removing a device with no iommu_group associated
2013-08-23 1:55 [PATCH] iommu: WARN_ON when removing a device with no iommu_group associated Wei Yang
@ 2013-08-23 3:33 ` Alex Williamson
2013-09-03 3:15 ` Wei Yang
0 siblings, 1 reply; 3+ messages in thread
From: Alex Williamson @ 2013-08-23 3:33 UTC (permalink / raw)
To: Wei Yang; +Cc: benh, aik, linux-kernel, iommu, paulus, linuxppc-dev
[+cc iommu]
On Fri, 2013-08-23 at 09:55 +0800, Wei Yang wrote:
> 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 <weiyang@linux.vnet.ibm.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
> ---
> 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);
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] iommu: WARN_ON when removing a device with no iommu_group associated
2013-08-23 3:33 ` Alex Williamson
@ 2013-09-03 3:15 ` Wei Yang
0 siblings, 0 replies; 3+ messages in thread
From: Wei Yang @ 2013-09-03 3:15 UTC (permalink / raw)
To: Alex Williamson
Cc: Wei Yang, benh, aik, linux-kernel, iommu, paulus, linuxppc-dev
Any more comments? Or this one is not proper?
On Thu, Aug 22, 2013 at 09:33:27PM -0600, Alex Williamson wrote:
>[+cc iommu]
>
>On Fri, 2013-08-23 at 09:55 +0800, Wei Yang wrote:
>> 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 <weiyang@linux.vnet.ibm.com>
>
>Acked-by: Alex Williamson <alex.williamson@redhat.com>
>
>> ---
>> 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);
>
>
--
Richard Yang
Help you, Help me
^ permalink raw reply [flat|nested] 3+ messages in thread
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