Hi! Thanks for review.

On ²â, äÕÒ 5, 2019 at 6:42 PM, Vladislav Shpilevoy 
<v.shpilevoy@tarantool.org> wrote:
> Hi! Thanks for the patch! See 5 comments below.

> 1. Instead of duplicating commit title, it is usually
> better to describe here a reason why the bug existed.
Done.

> 
> 2. Please, put branch and issue links after '---'.
> 
>> ---
Sorry.

> 4. Instead of checking for modules != NULL in each public func.h 
> function,
> it is better to move module_init() call from box_cfg_xc() to 
> box_init(). Then
> main() will create modules hash.
diff --git a/src/box/box.cc b/src/box/box.cc
index 8892d0f0e..6494a0f44 100644
--- a/src/box/box.cc
+++ b/src/box/box.cc
@@ -2053,6 +2053,9 @@ box_init(void)
 	 */
 	session_init();

+	if (module_init() != 0)
+		diag_raise();
+
 	if (tuple_init(lua_hash) != 0)
 		diag_raise();

@@ -2080,8 +2083,6 @@ box_cfg_xc(void)

 	gc_init();
 	engine_init();
-	if (module_init() != 0)
-		diag_raise();
 	schema_init();
 	replication_init();
 	port_init();

> 5. Not-tap tests are always run with already called box.cfg(),
> so these lines here will work regardless of your patch. Please,
> move it to a tap test, in app-tap directory. Now I do not see
> there any existing and suitable file for this test, so you
> should create a new one. For example, app-tap/func.test.lua.
diff --git a/test/app-tap/func.test.lua b/test/app-tap/func.test.lua
new file mode 100755
index 000000000..11bc01f1d
--- /dev/null
+++ b/test/app-tap/func.test.lua
@@ -0,0 +1,14 @@
+#!/usr/bin/env tarantool
+
+local tap = require('tap')
+
+local test = tap.test("func")
+
+test:plan(2)
+
+-- gh-3770 Check no segfault with module_reload() without box.cfg{}.
+
+test:ok(not pcall(box.internal.module_reload, ''),
+        'expected error: no module')
+test:ok(not pcall(box.internal.module_reload, 'xxx'),
+        'expected error: no module')


commit afd765d8bc86188c33cba3f06478853ec76bcaea
Author: Roman Khabibov <roman.habibov@tarantool.org>
Date:   Tue Feb 5 03:04:33 2019 +0300

    box: fix bug with module_reload() without box.cfg{}

    A bug existed because module_init was called during a call to 
box_cfg{}.
    Modules were not initialized before calling box.cfg{}.

    Closes #3770

diff --git a/src/box/box.cc b/src/box/box.cc
index 8892d0f0e..6494a0f44 100644
--- a/src/box/box.cc
+++ b/src/box/box.cc
@@ -2053,6 +2053,9 @@ box_init(void)
 	 */
 	session_init();

+	if (module_init() != 0)
+		diag_raise();
+
 	if (tuple_init(lua_hash) != 0)
 		diag_raise();

@@ -2080,8 +2083,6 @@ box_cfg_xc(void)

 	gc_init();
 	engine_init();
-	if (module_init() != 0)
-		diag_raise();
 	schema_init();
 	replication_init();
 	port_init();
diff --git a/test/app-tap/func.test.lua b/test/app-tap/func.test.lua
new file mode 100755
index 000000000..11bc01f1d
--- /dev/null
+++ b/test/app-tap/func.test.lua
@@ -0,0 +1,14 @@
+#!/usr/bin/env tarantool
+
+local tap = require('tap')
+
+local test = tap.test("func")
+
+test:plan(2)
+
+-- gh-3770 Check no segfault with module_reload() without box.cfg{}.
+
+test:ok(not pcall(box.internal.module_reload, ''),
+        'expected error: no module')
+test:ok(not pcall(box.internal.module_reload, 'xxx'),
+        'expected error: no module')