[PATCH v2 5/6] iommu/qcom: Publish pgtbl_ops before releasing init_mutex

[Mukesh Ojha]

qcom_domain->pgtbl_ops was assigned after mutex_unlock(). Another thread
calling qcom_iommu_init_domain() would see qcom_domain->iommu already set
(domain fully initialized) and skip re-initialization under the mutex.
If it then called qcom_iommu_map() before the first thread set pgtbl_ops,
it would observe a NULL ops pointer and return -ENODEV for valid mappings.

Move the assignment to before mutex_unlock() so that once the mutex is
released the domain is fully visible to concurrent operations.

Reviewed-by: Konrad Dybcio <konrad.dybcio at oss.qualcomm.com>
Signed-off-by: Mukesh Ojha <mukesh.ojha at oss.qualcomm.com>
---
 drivers/iommu/arm/arm-smmu/qcom_iommu.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu/qcom_iommu.c b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
index 222bb7febd03..ecde5ca2d476 100644
--- a/drivers/iommu/arm/arm-smmu/qcom_iommu.c
+++ b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
@@ -306,13 +306,12 @@ static int qcom_iommu_init_domain(struct iommu_domain *domain,
 		ctx->domain = domain;
 	}
 
-	mutex_unlock(&qcom_domain->init_mutex);
-
 	/* Publish page table ops for map/unmap */
 	qcom_domain->pgtbl_ops = pgtbl_ops;
 
-	return 0;
+	mutex_unlock(&qcom_domain->init_mutex);
 
+	return 0;
 out_clear_iommu:
 	free_io_pgtable_ops(pgtbl_ops);
 	qcom_domain->iommu = NULL;
-- 
2.53.0