genirq: Provide a lockdep helper

Some irq chips need to call genirq functions for nested chips from
their callbacks. That upsets lockdep. So they need to set a different
lock class for those nested chips. Provide a helper function to avoid
open access to irq_desc.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index 0b30662bc36ca4bc1dc134d20d1df6bddade8a18..1595f9176b43dc1e0f3d2c521cfb4f012d01c2dc 100644 (file)
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -191,6 +191,15 @@ static inline void __set_irq_handler_unlocked(int irq,
        desc->handle_irq = handler;
 }
 
+static inline void
+irq_set_lockdep_class(unsigned int irq, struct lock_class_key *class)
+{
+       struct irq_desc *desc = irq_to_desc(irq);
+
+       if (desc)
+               lockdep_set_class(&desc->lock, class);
+}
+
 #ifdef CONFIG_IRQ_PREFLOW_FASTEOI
 static inline void
 __irq_set_preflow_handler(unsigned int irq, irq_preflow_handler_t handler)