vfio: put off the allocation of "minor" in vfio_create_group

The next code fragment "list_for_each_entry" is not depend on "minor". With this
patch, the free of "minor" in "list_for_each_entry" can be reduced, and there is
no functional change.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 23ba12afe01fccf472be8a4d82635cb2c11350c4..86aac7e4a05017c9b2ff8f8b737e2c843073d1e3 100644 (file)
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -234,22 +234,21 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group)
 
        mutex_lock(&vfio.group_lock);
 
-       minor = vfio_alloc_group_minor(group);
-       if (minor < 0) {
-               vfio_group_unlock_and_free(group);
-               return ERR_PTR(minor);
-       }
-
        /* Did we race creating this group? */
        list_for_each_entry(tmp, &vfio.group_list, vfio_next) {
                if (tmp->iommu_group == iommu_group) {
                        vfio_group_get(tmp);
-                       vfio_free_group_minor(minor);
                        vfio_group_unlock_and_free(group);
                        return tmp;
                }
        }
 
+       minor = vfio_alloc_group_minor(group);
+       if (minor < 0) {
+               vfio_group_unlock_and_free(group);
+               return ERR_PTR(minor);
+       }
+
        dev = device_create(vfio.class, NULL,
                            MKDEV(MAJOR(vfio.group_devt), minor),
                            group, "%d", iommu_group_id(iommu_group));