linux-kernel - [PATCH 1/2] kobject: don't delay to cleanup module kobject

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Date:   Fri,  5 Nov 2021 14:37:09 +0800
From:   Ming Lei <ming.lei@...hat.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Petr Mladek <pmladek@...e.com>, linux-kernel@...r.kernel.org,
        Luis Chamberlain <mcgrof@...nel.org>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        Ming Lei <ming.lei@...hat.com>
Subject: [PATCH 1/2] kobject: don't delay to cleanup module kobject

CONFIG_DEBUG_KOBJECT_RELEASE is used for debugging kobject release/cleanup
issue. The module kobject is released after module_exit() returns. If
this kobject is delayed too much, and may cause other kobject's
cleaned up a bit earlier before freeing module, then real issue is
hidden.

So don't delay module kobject's cleanup, meantime module kobject is
always cleaned up synchronously, and we needn't module kobject's
cleanup.

Signed-off-by: Ming Lei <ming.lei@...hat.com>
---
 lib/kobject.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lib/kobject.c b/lib/kobject.c
index ea53b30cf483..4c0dbe11be3d 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -16,6 +16,7 @@
 #include <linux/stat.h>
 #include <linux/slab.h>
 #include <linux/random.h>
+#include <linux/module.h>
 
 /**
  * kobject_namespace() - Return @kobj's namespace tag.
@@ -727,6 +728,10 @@ static void kobject_release(struct kref *kref)
 	struct kobject *kobj = container_of(kref, struct kobject, kref);
 #ifdef CONFIG_DEBUG_KOBJECT_RELEASE
 	unsigned long delay = HZ + HZ * (get_random_int() & 0x3);
+
+	if (kobj->ktype == &module_ktype)
+		delay = 0;
+
 	pr_info("kobject: '%s' (%p): %s, parent %p (delayed %ld)\n",
 		 kobject_name(kobj), kobj, __func__, kobj->parent, delay);
 	INIT_DELAYED_WORK(&kobj->release, kobject_delayed_cleanup);
-- 
2.31.1