linux-kernel - [PATCH] kobject: hide illegible sysfs warning of kobject

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Date:   Fri, 11 Nov 2022 14:58:07 +0800
From:   Liu Shixin <liushixin2@...wei.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>
CC:     <linux-kernel@...r.kernel.org>, Liu Shixin <liushixin2@...wei.com>
Subject: [PATCH] kobject: hide illegible sysfs warning of kobject_del()

Some consumers do not care whether kobject_add() succeed or failed such as
irqdesc. They call kobject_del() all the time even if kobject_add() failed.
Then kernel will report some illegible sysfs warning like this:

 kernfs: can not remove 'actions', no directory
 WARNING: CPU: 0 PID: 277 at fs/kernfs/dir.c:1615 kernfs_remove_by_name_ns+0xd5/0xe0
[...]
 Call Trace:
  <TASK>
  remove_files.isra.0+0x3f/0xb0
  sysfs_remove_group+0x68/0xe0
  sysfs_remove_groups+0x41/0x70
  __kobject_del+0x45/0xc0
  kobject_del+0x2a/0x40
  free_desc+0x44/0x70
  irq_free_descs+0x5d/0x90
[...]

Check whether kobject is added successfully by using kobj->state_in_sysfs
in kobject_del() and skip deleting it if not added at all.

Signed-off-by: Liu Shixin <liushixin2@...wei.com>
---
 lib/kobject.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/kobject.c b/lib/kobject.c
index a0b2dbfcfa23..f6163a3a41c2 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -604,7 +604,7 @@ void kobject_del(struct kobject *kobj)
 {
 	struct kobject *parent;
 
-	if (!kobj)
+	if (!kobj || !kobj->state_in_sysfs)
 		return;
 
 	parent = kobj->parent;
-- 
2.25.1