Domain is getting created more than once during asynchronous multiple
display heads(devices) probe. All the display heads share same SID and
are expected to be in same domain. As iommu_alloc_default_domain() call
is not protected, the group->default_domain and group->domain are ending
up with different domains and leading to subsequent IOMMU faults.
Fix this by protecting iommu_alloc_default_domain() call with group->mutex.

Signed-off-by: Ashish Mhetre <amhe...@nvidia.com>
---
 drivers/iommu/iommu.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 808ab70..2700500 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -273,7 +273,9 @@ int iommu_probe_device(struct device *dev)
         * support default domains, so the return value is not yet
         * checked.
         */
+       mutex_lock(&group->mutex);
        iommu_alloc_default_domain(group, dev);
+       mutex_unlock(&group->mutex);
 
        if (group->default_domain) {
                ret = __iommu_attach_device(group->default_domain, dev);
-- 
2.7.4

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