From 9403b3d7a39ea80f95ae71f386d6949f52284426 Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Thu, 20 Dec 2018 17:31:55 +0100
Subject: [PATCH] Modules shared API: prevent unloading of used modules.

---
 src/module.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/module.c b/src/module.c
index eafdd81f6..4f0e5b126 100644
--- a/src/module.c
+++ b/src/module.c
@@ -4896,11 +4896,12 @@ int moduleUnload(sds name) {
     if (module == NULL) {
         errno = ENOENT;
         return REDISMODULE_ERR;
-    }
-
-    if (listLength(module->types)) {
+    } else if (listLength(module->types)) {
         errno = EBUSY;
         return REDISMODULE_ERR;
+    } else if (listLength(module->usedby)) {
+        errno = EPERM;
+        return REDISMODULE_ERR;
     }
 
     moduleUnregisterCommands(module);
@@ -4966,7 +4967,12 @@ NULL
                 errmsg = "no such module with that name";
                 break;
             case EBUSY:
-                errmsg = "the module exports one or more module-side data types, can't unload";
+                errmsg = "the module exports one or more module-side data "
+                         "types, can't unload";
+                break;
+            case EPERM:
+                errmsg = "the module exports APIs used by other modules. "
+                         "Please unload them first and try again";
                 break;
             default:
                 errmsg = "operation not possible.";