vpp-83: fix double-unlock

Change-Id: I0b75b4f9bef62aba69e9cc163924f6b985a35455
Signed-off-by: Dave Barach <dave@barachs.net>
diff --git a/vlib-api/vlibmemory/memory_shared.c b/vlib-api/vlibmemory/memory_shared.c
index 1684acf..e4f5dd0 100644
--- a/vlib-api/vlibmemory/memory_shared.c
+++ b/vlib-api/vlibmemory/memory_shared.c
@@ -288,8 +288,9 @@
             pthread_mutex_lock (&root_rp->mutex);
             svm_client_scan_this_region_nolock (root_rp);
             pthread_mutex_unlock (&root_rp->mutex);
-        } 
-        pthread_mutex_unlock (&vlib_rp->mutex);
+        } else {
+            pthread_mutex_unlock (&vlib_rp->mutex);
+        }
         am->vlib_rp = vlib_rp;
         vec_add1(am->mapped_shmem_regions, vlib_rp);
         return 0;