md: extend spinlock protection in register_md_cluster_operations

This code looks racy. The only possible race is if two modules try to register at the same time and that won't happen. But make the code look safe anyway. Signed-off-by: NeilBrown <[email protected]>
nkskjames · Aug 31, 2015 · 6022e75 · 6022e75
1 parent abb9b22
commit 6022e75
Showing 1 changed file with 10 additions and 6 deletions.
diff --git a/drivers/md/md.c b/drivers/md/md.c
@@ -7427,15 +7427,19 @@ int unregister_md_personality(struct md_personality *p)
 }
 EXPORT_SYMBOL(unregister_md_personality);
 
-int register_md_cluster_operations(struct md_cluster_operations *ops, struct module *module)
+int register_md_cluster_operations(struct md_cluster_operations *ops,
+				   struct module *module)
 {
-	if (md_cluster_ops != NULL)
-		return -EALREADY;
+	int ret = 0;
 	spin_lock(&pers_lock);
-	md_cluster_ops = ops;
-	md_cluster_mod = module;
+	if (md_cluster_ops != NULL)
+		ret = -EALREADY;
+	else {
+		md_cluster_ops = ops;
+		md_cluster_mod = module;
+	}
 	spin_unlock(&pers_lock);
-	return 0;
+	return ret;
 }
 EXPORT_SYMBOL(register_md_cluster_operations);