genirq: Warn if enable_irq is called before irq is set up

The recent changes in the genirq core unearthed a bug in arch/um which
called enable_irq() before the interrupt was set up.

Warn and return instead of crashing the machine with a NULL pointer
dereference.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Richard Weinberger <richard@nod.at>

1 files changed, 4 insertions, 0 deletions

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 644e8d5fa367..5f92acc5f952 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -324,6 +324,10 @@ void enable_irq(unsigned int irq)
         if (!desc)
                 return;
 
+        if (WARN(!desc->irq_data.chip || !desc->irq_data.chip->irq_enable,
+            KERN_ERR "enable_irq before setup/request_irq: irq %u\n", irq))
+                return;
+
         chip_bus_lock(desc);
         raw_spin_lock_irqsave(&desc->lock, flags);
         __enable_irq(desc, irq, false);