From d0ff14fdc987303aeeb7de6f1bd72c3749ae2a9b Mon Sep 17 00:00:00 2001

From: Michael Kelley <mikelley@microsoft.com>

Date: Thu, 1 Aug 2019 23:53:53 +0000

Subject: [PATCH] genirq: Properly pair kobject_del() with kobject_add()

Git-commit: d0ff14fdc987303aeeb7de6f1bd72c3749ae2a9b

Patch-mainline: v5.3-rc6

References: bsc#1051510

If alloc_descs() fails before irq_sysfs_init() has run, free_desc() in the

cleanup path will call kobject_del() even though the kobject has not been

added with kobject_add().

Fix this by making the call to kobject_del() conditional on whether

irq_sysfs_init() has run.

This problem surfaced because commit aa30f47cf666 ("kobject: Add support

for default attribute groups to kobj_type") makes kobject_del() stricter

about pairing with kobject_add(). If the pairing is incorrrect, a WARNING

and backtrace occur in sysfs_remove_group() because there is no parent.

[ tglx: Add a comment to the code and make it work with CONFIG_SYSFS=n ]

Fixes: ecb3f394c5db ("genirq: Expose interrupt information through sysfs")

Signed-off-by: Michael Kelley <mikelley@microsoft.com>

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Cc: stable@vger.kernel.org

Link: https://lkml.kernel.org/r/1564703564-4116-1-git-send-email-mikelley@microsoft.com

Acked-by: Takashi Iwai <tiwai@suse.de>

---

 kernel/irq/irqdesc.c | 15 ++++++++++++++-

 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c

index 9484e88dabc2..9be995fc3c5a 100644

--- a/kernel/irq/irqdesc.c

+++ b/kernel/irq/irqdesc.c

@@ -295,6 +295,18 @@ static void irq_sysfs_add(int irq, struct irq_desc *desc)

 	}

 }

+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.

+	 * kobject_del() complains about a object with no parent, so make

+	 * it conditional.

+	 */

+	if (irq_kobj_base)

+		kobject_del(&desc->kobj);

+}

+

 static int __init irq_sysfs_init(void)

 {

 	struct irq_desc *desc;

@@ -325,6 +337,7 @@ static struct kobj_type irq_kobj_type = {

 };

 static void irq_sysfs_add(int irq, struct irq_desc *desc) {}

+static void irq_sysfs_del(struct irq_desc *desc) {}

 #endif /* CONFIG_SYSFS */

@@ -438,7 +451,7 @@ static void free_desc(unsigned int irq)

 	 * The sysfs entry must be serialized against a concurrent

 	 * irq_sysfs_init() as well.

 	 */

-	kobject_del(&desc->kobj);

+	irq_sysfs_del(desc);

 	delete_irq_desc(irq);

 	/*

-- 

2.16.4