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

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Date:   Sat, 12 Nov 2022 17:39:39 +0800
From:   Liu Shixin <liushixin2@...wei.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Rafael J . Wysocki" <rafael@...nel.org>
CC:     <linux-kernel@...r.kernel.org>, Liu Shixin <liushixin2@...wei.com>
Subject: [PATCH] genirq/irqdesc: hide illegible sysfs warning of kobject_del()

If irq_sysfs_add() failed, system will report a warning but don't call
kobject_put() to release the descriptor. Then in irq_sysfs_del(), we
continue to call kobject_del(). In such situation, kobject_del() will
complains about a object with no parent 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
[...]

Use kobj->state_in_sysfs to check whether kobject is added succeed. And
if not, we should not call kobject_del().

Signed-off-by: Liu Shixin <liushixin2@...wei.com>
---
 kernel/irq/irqdesc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index a91f9001103c..a820d96210d4 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -300,10 +300,11 @@ static void irq_sysfs_del(struct irq_desc *desc)
 	/*
 	 * If irq_sysfs_init() has not yet been invoked (early boot), then
 	 * irq_kobj_base is NULL and the descriptor was never added.
+	 * And the descriptor may be added failed.
 	 * kobject_del() complains about a object with no parent, so make
 	 * it conditional.
 	 */
-	if (irq_kobj_base)
+	if (irq_kobj_base && desc->kobj.parent)
 		kobject_del(&desc->kobj);
 }
 
-- 
2.25.1