[PATCH v2] genirq/irqdesc: fix WARNING in irq_sysfs_del()

[Yang Yingliang]

I got the lots of WARNING report when doing fault injection test:

kernfs: can not remove 'chip_name', no directory
WARNING: CPU: 0 PID: 253 at fs/kernfs/dir.c:1616 kernfs_remove_by_name_ns+0xce/0xe0
RIP: 0010:kernfs_remove_by_name_ns+0xce/0xe0
Call Trace:
 <TASK>
 remove_files.isra.1+0x3f/0xb0
 sysfs_remove_group+0x68/0xe0
 sysfs_remove_groups+0x41/0x70
 __kobject_del+0x45/0xc0
 kobject_del+0x29/0x40
 free_desc+0x42/0x70
 irq_free_descs+0x5e/0x90

kernfs: can not remove 'hwirq', no directory
WARNING: CPU: 0 PID: 253 at fs/kernfs/dir.c:1616 kernfs_remove_by_name_ns+0xce/0xe0
RIP: 0010:kernfs_remove_by_name_ns+0xce/0xe0
Call Trace:
 <TASK>
 remove_files.isra.1+0x3f/0xb0
 sysfs_remove_group+0x68/0xe0
 sysfs_remove_groups+0x41/0x70
 __kobject_del+0x45/0xc0
 kobject_del+0x29/0x40
 free_desc+0x42/0x70
 irq_free_descs+0x5e/0x90

If irq_sysfs_add() fails in alloc_descs(), the directory of interrupt
informations is not added to sysfs, it causes the WARNINGs when removing
the information files. Add 'sysfs_added' field in struct irq_desc to
indicate if it is added, and check it before calling kobject_del() to
avoid these WARNINGs.

Fixes: ecb3f394c5db ("genirq: Expose interrupt information through sysfs")
Signed-off-by: Yang Yingliang <yangyingliang@xxxxxxxxxx>
---
v1 -> v2:
  Don't use state_in_sysfs, introduce 'sysfs_added' to indicate if it is added.
---
 include/linux/irqdesc.h | 1 +
 kernel/irq/irqdesc.c    | 7 +++++--
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index 844a8e30e6de..fec0f3946a34 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -97,6 +97,7 @@ struct irq_desc {
 #ifdef CONFIG_SPARSE_IRQ
 	struct rcu_head		rcu;
 	struct kobject		kobj;
+	bool			sysfs_added;
 #endif
 	struct mutex		request_mutex;
 	int			parent_irq;
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index a91f9001103c..9bf74d11bad5 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -292,6 +292,8 @@ static void irq_sysfs_add(int irq, struct irq_desc *desc)
 		 */
 		if (kobject_add(&desc->kobj, irq_kobj_base, "%d", irq))
 			pr_warn("Failed to add kobject for irq %d\n", irq);
+		else
+			desc->sysfs_added = true;
 	}
 }
 
@@ -299,11 +301,12 @@ 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.
+	 * irq_kobj_base is NULL or kobject_add() fails, the descriptor was
+	 * never added.
 	 * kobject_del() complains about a object with no parent, so make
 	 * it conditional.
 	 */
-	if (irq_kobj_base)
+	if (desc->sysfs_added)
 		kobject_del(&desc->kobj);
 }
 
-- 
2.25.1