genirq: Free irq_desc with rcu

[cascardo/linux.git] / kernel / irq / irqdesc.c

diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 239e2ae..0409da0 100644 (file)
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -159,6 +159,7 @@ static struct irq_desc *alloc_desc(int irq, int node, struct module *owner)
 
        raw_spin_lock_init(&desc->lock);
        lockdep_set_class(&desc->lock, &irq_desc_lock_class);
+       init_rcu_head(&desc->rcu);
 
        desc_set_defaults(irq, desc, node, owner);
 
@@ -171,6 +172,15 @@ err_desc:
        return NULL;
 }
 
+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);
@@ -187,9 +197,12 @@ static void free_desc(unsigned int irq)
        delete_irq_desc(irq);
        mutex_unlock(&sparse_irq_lock);
 
-       free_masks(desc);
-       free_percpu(desc->kstat_irqs);
-       kfree(desc);
+       /*
+        * We free the descriptor, masks and stat fields via RCU. That
+        * allows demultiplex interrupts to do rcu based management of
+        * the child interrupts.
+        */
+       call_rcu(&desc->rcu, delayed_free_desc);
 }
 
 static int alloc_descs(unsigned int start, unsigned int cnt, int node,