Thread (50 messages) 50 messages, 5 authors, 2021-02-02

Re: [PATCH v6 07/33] iommu: Avoid reallocate default domain for a group

From: Yong Wu <yong.wu@mediatek.com>
Date: 2021-01-27 09:42:50
Also in: linux-arm-kernel, linux-iommu, linux-mediatek, lkml

On Tue, 2021-01-26 at 22:23 +0000, Will Deacon wrote:
On Mon, Jan 11, 2021 at 07:18:48PM +0800, Yong Wu wrote:
quoted
If group->default_domain exists, avoid reallocate it.

In some iommu drivers, there may be several devices share a group. Avoid
realloc the default domain for this case.

Signed-off-by: Yong Wu <yong.wu@mediatek.com>
---
 drivers/iommu/iommu.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 3d099a31ddca..f4b87e6abe80 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -266,7 +266,8 @@ int iommu_probe_device(struct device *dev)
 	 * support default domains, so the return value is not yet
 	 * checked.
 	 */
-	iommu_alloc_default_domain(group, dev);
+	if (!group->default_domain)
+		iommu_alloc_default_domain(group, dev);
I don't really get what this achieves, since iommu_alloc_default_domain()
looks like this:

static int iommu_alloc_default_domain(struct iommu_group *group,
				      struct device *dev)
{
	unsigned int type;

	if (group->default_domain)
		return 0;

	...

in which case, it should be fine?
oh. sorry, I overlooked this. the current code is enough.
I will remove this patch. and send the next version in this week.
Thanks very much.
Will
  
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