Commit 42731def authored Aug 01, 2019 by Michael Kelley Committed by Greg Kroah-Hartman Aug 29, 2019

genirq: Properly pair kobject_del() with kobject_add()



commit d0ff14fdc987303aeeb7de6f1bd72c3749ae2a9b upstream.

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: ecb3f394 ("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


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

parent c14fe4e8

kernel/irq/irqdesc.c

+14 −1

Original line number	Diff line number	Diff line
		@@ -294,6 +294,18 @@ 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;
		@@ -324,6 +336,7 @@ 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 */

		@@ -437,7 +450,7 @@ 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);

		/*