[XEN][RFC PATCH v4 08/16] xen/iommu: protect iommu_add_dt_device() with dtdevs_lock

[Vikram Garhwal <vikram.garhwal@xxxxxxx>]

Protect iommu_add_dt_device() with dtdevs_lock to prevent concurrent access add.

Signed-off-by: Vikram Garhwal <vikram.garhwal@xxxxxxx>
Reviewed-by: Luca Fancellu <luca.fancellu@xxxxxxx>
---
 xen/drivers/passthrough/device_tree.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/xen/drivers/passthrough/device_tree.c 
b/xen/drivers/passthrough/device_tree.c
index bb4cf7784d..457df333a0 100644
--- a/xen/drivers/passthrough/device_tree.c
+++ b/xen/drivers/passthrough/device_tree.c
@@ -146,6 +146,8 @@ int iommu_add_dt_device(struct dt_device_node *np)
     if ( dev_iommu_fwspec_get(dev) )
         return 0;
 
+    spin_lock(&dtdevs_lock);
+
     /*
      * According to the Documentation/devicetree/bindings/iommu/iommu.txt
      * from Linux.
@@ -158,7 +160,10 @@ int iommu_add_dt_device(struct dt_device_node *np)
          * these callback implemented.
          */
         if ( !ops->add_device || !ops->dt_xlate )
-            return -EINVAL;
+        {
+            rc = -EINVAL;
+            goto fail;
+        }
 
         if ( !dt_device_is_available(iommu_spec.np) )
             break;
@@ -189,6 +194,8 @@ int iommu_add_dt_device(struct dt_device_node *np)
     if ( rc < 0 )
         iommu_fwspec_free(dev);
 
+fail:
+    spin_unlock(&dtdevs_lock);
     return rc;
 }
 
-- 
2.17.1