Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull irq updates from Thomas Gleixner:
 "The irq department provides:

   - Support for MSI to wire bridges and a first user of it

   - More ACPI support for ARM/GIC

   - A new TS-4800 interrupt controller driver

   - RCU based free of interrupt descriptors to support the upcoming
     Intel VMD technology without introducing a locking nightmare

   - The usual pile of fixes and updates to drivers and core code"

* 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (41 commits)
  irqchip/omap-intc: Add support for spurious irq handling
  irqchip/zevio: Use irq_data_get_chip_type() helper
  irqchip/omap-intc: Remove duplicate setup for IRQ chip type handler
  irqchip/ts4800: Add TS-4800 interrupt controller
  irqchip/ts4800: Add documentation for TS-4800 interrupt controller
  irq/platform-MSI: Increase the maximum MSIs the MSI framework can support
  irqchip/gicv2m: Miscellaneous fixes for v2m resources and SPI ranges
  irqchip/bcm2836: Make code more readable
  irqchip/bcm2836: Tolerate IRQs while no flag is set in ISR
  irqchip/bcm2836: Add SMP support for the 2836
  irqchip/bcm2836: Fix initialization of the LOCAL_IRQ_CNT timers
  irqchip/gic-v2m: acpi: Introducing GICv2m ACPI support
  irqchip/gic-v2m: Refactor to prepare for ACPI support
  irqdomain: Introduce is_fwnode_irqchip helper
  acpi: pci: Setup MSI domain for ACPI based pci devices
  genirq/msi: Export functions to allow MSI domains in modules
  irqchip/mbigen: Implement the mbigen irq chip operation functions
  irqchip/mbigen: Create irq domain for each mbigen device
  irqchip/mgigen: Add platform device driver for mbigen device
  dt-bindings: Documents the mbigen bindings
  ...

1 files changed, 16 insertions, 3 deletions

diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 239e2ae2c947..0409da0bcc33 100644
--- 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,