[PATCH] iommu: Fix iommu_sva_bind_device to the same domain

[Zhangfei Gao]

The accelerator dev can provide multi-queue and bind to
the same domain in multi-thread for better performance,
and domain refcount takes care of it.

'commit 092edaddb660 ("iommu: Support mm PASID 1:n with sva domains")'
removes the possibility, so fix it

Fixs: '092edaddb660 ("iommu: Support mm PASID 1:n with sva domains")'
Signed-off-by: Zhangfei Gao <zhangfei.gao@xxxxxxxxxx>
---
 drivers/iommu/iommu-sva.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
index c3fc9201d0be..a95c8f3a5407 100644
--- a/drivers/iommu/iommu-sva.c
+++ b/drivers/iommu/iommu-sva.c
@@ -91,7 +91,7 @@ struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm
 	/* Search for an existing domain. */
 	list_for_each_entry(domain, &mm->iommu_mm->sva_domains, next) {
 		ret = iommu_attach_device_pasid(domain, dev, iommu_mm->pasid);
-		if (!ret) {
+		if (!ret || ret == -EBUSY) {
 			domain->users++;
 			goto out;
 		}
@@ -141,8 +141,8 @@ void iommu_sva_unbind_device(struct iommu_sva *handle)
 	struct device *dev = handle->dev;
 
 	mutex_lock(&iommu_sva_lock);
-	iommu_detach_device_pasid(domain, dev, iommu_mm->pasid);
 	if (--domain->users == 0) {
+		iommu_detach_device_pasid(domain, dev, iommu_mm->pasid);
 		list_del(&domain->next);
 		iommu_domain_free(domain);
 	}
-- 
2.34.1