[PATCH 2/2] irqdomain: Support one-shot tear down of domain mappings.

[Paul Mundt <lethal@linux-sh.org>]

This implements a sledgehammer approach for batched domain unmapping
regardless of domain type. In the linear revmap case it's fairly easy to
track state and iterate over the IRQs disposing of them one at a time,
but it's not always so straightforward in the radix tree case.

A new irq_domain_dispose_mappings() is added to ensure all of the
mappings are appropriately discarded, and is to be used prior to domain
removal. Gang lookups are batched, presently 16 at a time, for no reason
other than it seemed like a good number at the time.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
---
 include/linux/irqdomain.h |    1 +
 kernel/irq/irqdomain.c    |   43 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 0 deletions(-)

diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
index 58defd5..6f27c55 100644
--- a/include/linux/irqdomain.h
+++ b/include/linux/irqdomain.h
@@ -149,6 +149,7 @@ static inline int irq_domain_associate(struct irq_domain *domain, unsigned int i
 extern unsigned int irq_create_mapping(struct irq_domain *host,
 				       irq_hw_number_t hwirq);
 extern void irq_dispose_mapping(unsigned int virq);
+extern void irq_domain_dispose_mappings(struct irq_domain *domain);
 extern unsigned int irq_find_mapping(struct irq_domain *host,
 				     irq_hw_number_t hwirq);
 extern unsigned int irq_create_direct_mapping(struct irq_domain *host);
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 8591cb6..40c9ba1 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -546,6 +546,49 @@ void irq_dispose_mapping(unsigned int virq)
 }
 EXPORT_SYMBOL_GPL(irq_dispose_mapping);
 
+#define IRQ_DOMAIN_BATCH_IRQS	16
+
+/**
+ * irq_domain_dispose_mappings() - Dispose of all mappings in a domain
+ * @domain: domain to tear down
+ */
+void irq_domain_dispose_mappings(struct irq_domain *domain)
+{
+	if (domain->revmap_type = IRQ_DOMAIN_MAP_NOMAP)
+		return;
+
+	if (domain->linear_size) {
+		int i;
+
+		for (i = 0; i < domain->linear_size; i++)
+			irq_dispose_mapping(domain->linear_revmap[i]);
+	} else {
+		struct irq_data *irq_data_batch[IRQ_DOMAIN_BATCH_IRQS];
+		unsigned int nr_found;
+		unsigned long index = 0;
+
+		rcu_read_lock();
+
+		for (;;) {
+			int i;
+
+			nr_found = radix_tree_gang_lookup(&domain->radix_tree,
+					(void **)irq_data_batch, index,
+					ARRAY_SIZE(irq_data_batch));
+			if (!nr_found)
+				break;
+
+			for (i = 0; i < nr_found; i++)
+				irq_dispose_mapping(irq_data_batch[i]->irq);
+
+			index += nr_found;
+		}
+
+		rcu_read_unlock();
+	}
+}
+EXPORT_SYMBOL_GPL(irq_domain_dispose_mappings);
+
 /**
  * irq_find_mapping() - Find a linux irq from an hw irq number.
  * @domain: domain owning this hardware interrupt
-- 
1.7.9.rc0.28.g0e1cf