iommu: Move lock from iommu_change_dev_def_domain() to its caller

The intention is to make it possible to put group ownership check and
default domain change in a same critical region protected by the group's
mutex lock. No intentional functional change.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20230322064956.263419-5-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 419d565..32c51e6 100644 (file)
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2889,7 +2889,7 @@ static int iommu_change_dev_def_domain(struct iommu_group *group,
        int ret, dev_def_dom;
        struct device *dev;
 
-       mutex_lock(&group->mutex);
+       lockdep_assert_held(&group->mutex);
 
        if (group->default_domain != group->domain) {
                dev_err_ratelimited(prev_dev, "Group not assigned to default domain\n");
@@ -2978,28 +2978,15 @@ static int iommu_change_dev_def_domain(struct iommu_group *group,
                goto free_new_domain;
 
        group->domain = group->default_domain;
-
-       /*
-        * Release the mutex here because ops->probe_finalize() call-back of
-        * some vendor IOMMU drivers calls arm_iommu_attach_device() which
-        * in-turn might call back into IOMMU core code, where it tries to take
-        * group->mutex, resulting in a deadlock.
-        */
-       mutex_unlock(&group->mutex);
-
-       /* Make sure dma_ops is appropriatley set */
-       iommu_group_do_probe_finalize(dev, group->default_domain);
        iommu_domain_free(prev_dom);
+
        return 0;
 
 free_new_domain:
        iommu_domain_free(group->default_domain);
        group->default_domain = prev_dom;
        group->domain = prev_dom;
-
 out:
-       mutex_unlock(&group->mutex);
-
        return ret;
 }
 
@@ -3089,7 +3076,19 @@ static ssize_t iommu_group_store_type(struct iommu_group *group,
                goto out;
        }
 
+       mutex_lock(&group->mutex);
        ret = iommu_change_dev_def_domain(group, dev, req_type);
+       /*
+        * Release the mutex here because ops->probe_finalize() call-back of
+        * some vendor IOMMU drivers calls arm_iommu_attach_device() which
+        * in-turn might call back into IOMMU core code, where it tries to take
+        * group->mutex, resulting in a deadlock.
+        */
+       mutex_unlock(&group->mutex);
+
+       /* Make sure dma_ops is appropriatley set */
+       if (!ret)
+               iommu_group_do_probe_finalize(dev, group->default_domain);
        ret = ret ?: count;
 
 out: