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Subject[PATCH V2 1/2] kobject: don't delay to cleanup module kobject
Date
CONFIG_DEBUG_KOBJECT_RELEASE is used for debugging kobject release and
cleanup issue. The module kobject is released after module_exit() returns.
If this kobject is delayed too much, and may cause other kobjects 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 CONFIG_DEBUG_KOBJECT_RELEASE is
actually needless for module kobject.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
lib/kobject.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)

diff --git a/lib/kobject.c b/lib/kobject.c
index 4a56f519139d..b81319b0bd5a 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 +728,19 @@ 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);
+
+ /*
+ * Don't delay to release module kobject so that we can detect late
+ * kobject release more effectively because module unloading waits
+ * for completion of module kobject release, see mod_kobject_put.
+ *
+ * Meantime mod_kobject_put() always waits for completion of module
+ * kobject's release, CONFIG_DEBUG_KOBJECT_RELEASE is basically
+ * useless for debugging module kobject's release.
+ */
+ 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
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