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Subject[PATCH kernel v4 4/8] genirq: Free IRQ descriptor via embedded kobject
Date
At the moment the IRQ descriptor is freed via the free_desc() helper.
We want to add reference counting to IRQ descriptors and there is already
kobj embedded into irq_desc which we want to reuse.

This shuffles free_desc()/etc to make it simply call kobject_put() and
moves all the cleanup into the kobject_release hook.

As a bonus, we do not need irq_sysfs_del() as kobj removes itself from
sysfs if it knows that it was added.

This should cause no behavioral change.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
kernel/irq/irqdesc.c | 42 ++++++++++++------------------------------
1 file changed, 12 insertions(+), 30 deletions(-)

diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 1a7723604399..75374b7944b5 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -295,18 +295,6 @@ 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;
@@ -337,7 +325,6 @@ 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 */

@@ -419,39 +406,34 @@ static struct irq_desc *alloc_desc(int irq, int node, unsigned int flags,
return NULL;
}

-static void irq_kobj_release(struct kobject *kobj)
-{
- struct irq_desc *desc = container_of(kobj, struct irq_desc, kobj);
-
- free_masks(desc);
- free_percpu(desc->kstat_irqs);
- kfree(desc);
-}
-
static void delayed_free_desc(struct rcu_head *rhp)
{
struct irq_desc *desc = container_of(rhp, struct irq_desc, rcu);

+ free_masks(desc);
+ free_percpu(desc->kstat_irqs);
+ kfree(desc);
+}
+
+static void free_desc(unsigned int irq)
+{
+ struct irq_desc *desc = irq_to_desc(irq);
+
kobject_put(&desc->kobj);
}

-static void free_desc(unsigned int irq)
+static void irq_kobj_release(struct kobject *kobj)
{
- struct irq_desc *desc = irq_to_desc(irq);
+ struct irq_desc *desc = container_of(kobj, struct irq_desc, kobj);
+ unsigned int irq = desc->irq_data.irq;

irq_remove_debugfs_entry(desc);
unregister_irq_proc(irq, desc);

/*
- * sparse_irq_lock protects also show_interrupts() and
- * kstat_irq_usr(). Once we deleted the descriptor from the
- * sparse tree we can free it. Access in proc will fail to
- * lookup the descriptor.
- *
* The sysfs entry must be serialized against a concurrent
* irq_sysfs_init() as well.
*/
- irq_sysfs_del(desc);
delete_irq_desc(irq);

/*
--
2.17.1
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