Em Thu, 5 May 2022 23:35:29 +0200
Andi Shyti [off-list ref] escreveu:

Hi Mauro,

[...]

quoted

+static int ref_module_dependency(struct module *mod, struct module *this)
+{
+	int ret;
+
+	if (!this || !this->name)
+		return -EINVAL;
+
+	if (mod == this)
+		return 0;
+
+	mutex_lock(&module_mutex);
+
+	ret = ref_module(this, mod);
+
+#ifdef CONFIG_MODULE_UNLOAD
+	if (ret)
+		goto ret;
+
+	ret = sysfs_create_link(mod->holders_dir,
+				&this->mkobj.kobj, this->name);
+#endif
+
+ret:
+	mutex_unlock(&module_mutex);
+	return ret;
+}
+
 /* Clear the unload stuff of the module. */
 static void module_unload_free(struct module *mod)
 {

@@ -841,24 +886,16 @@ void __module_get(struct module *module)
 }
 EXPORT_SYMBOL(__module_get);
 
-bool try_module_get(struct module *module)
+bool try_module_get_owner(struct module *module, struct module *this)
 {
-	bool ret = true;
+	int ret = __try_module_get(module);
 
-	if (module) {
-		preempt_disable();
-		/* Note: here, we can fail to get a reference */
-		if (likely(module_is_live(module) &&
-			   atomic_inc_not_zero(&module->refcnt) != 0))
-			trace_module_get(module, _RET_IP_);
-		else
-			ret = false;
+	if (ret)
+		ref_module_dependency(module, this);  

do we care about the return value here?

I don't think it should care about the return value, as a failure to
create a sysfs node for the holder or to add it to the holders list
is not fatal: modules can still continue working without that.

Also, I opted to be conservative here: currently, not creating these
doesn't cause try_module_get() to fail. I'm not sure what would be the
impact if this starts to fail.

So, right now, I'm opting to just ignore the return value. Perhaps
in the future this could a warning (similarly to what sysfs create
link does).

Regards,
Mauro

Andi

quoted

 
-		preempt_enable();
-	}
 	return ret;
 }
-EXPORT_SYMBOL(try_module_get);
+EXPORT_SYMBOL(try_module_get_owner);
 
 void module_put(struct module *module)
 {
-- 
2.35.1  

Thanks,
Mauro