genirq: Wake up irq thread after action has been installed

The wake_up_process() of the new irq thread in __setup_irq() is too
early as the irqaction is not yet fully initialized especially
action->irq is not yet set. The interrupt thread might dereference the
wrong irq descriptor.

Move the wakeup after the action is installed and action->irq has been
set.

Reported-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Michael Buesch <mb@bu3sch.de>

1 files changed, 8 insertions, 2 deletions

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index d222515a5a0..0ec9ed83173 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -607,7 +607,6 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
                  */
                 get_task_struct(t);
                 new->thread = t;
-                wake_up_process(t);
         }
 
         /*
@@ -690,6 +689,7 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
                                 (int)(new->flags & IRQF_TRIGGER_MASK));
         }
 
+        new->irq = irq;
         *old_ptr = new;
 
         /* Reset broken irq detection when installing new handler */
@@ -707,7 +707,13 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 
         spin_unlock_irqrestore(&desc->lock, flags);
 
-        new->irq = irq;
+        /*
+         * Strictly no need to wake it up, but hung_task complains
+         * when no hard interrupt wakes the thread up.
+         */
+        if (new->thread)
+                wake_up_process(new->thread);
+
         register_irq_proc(irq, desc);
         new->dir = NULL;
         register_handler_proc(irq, new);