genirq: threaded irq handlers review fixups

Delta patch to address the review comments.

      - Implement warning when IRQ_WAKE_THREAD is requested and no
        thread handler installed
      - coding style fixes

Pointed-out-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 24 insertions, 5 deletions

diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index fe8f45374e86..38b49a9e508a 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -338,6 +338,15 @@ irqreturn_t no_action(int cpl, void *dev_id)
         return IRQ_NONE;
 }
 
+static void warn_no_thread(unsigned int irq, struct irqaction *action)
+{
+        if (test_and_set_bit(IRQTF_WARNED, &action->thread_flags))
+                return;
+
+        printk(KERN_WARNING "IRQ %d device %s returned IRQ_WAKE_THREAD "
+               "but no thread function available.", irq, action->name);
+}
+
 /**
  * handle_IRQ_event - irq action chain handler
  * @irq:        the interrupt number
@@ -361,6 +370,21 @@ irqreturn_t handle_IRQ_event(unsigned int irq, struct irqaction *action)
                 switch (ret) {
                 case IRQ_WAKE_THREAD:
                         /*
+                         * Set result to handled so the spurious check
+                         * does not trigger.
+                         */
+                        ret = IRQ_HANDLED;
+
+                        /*
+                         * Catch drivers which return WAKE_THREAD but
+                         * did not set up a thread function
+                         */
+                        if (unlikely(!action->thread_fn)) {
+                                warn_no_thread(irq, action);
+                                break;
+                        }
+
+                        /*
                          * Wake up the handler thread for this
                          * action. In case the thread crashed and was
                          * killed we just pretend that we handled the
@@ -374,11 +398,6 @@ irqreturn_t handle_IRQ_event(unsigned int irq, struct irqaction *action)
                                 wake_up_process(action->thread);
                         }
 
-                        /*
-                         * Set it to handled so the spurious check
-                         * does not trigger.
-                         */
-                        ret = IRQ_HANDLED;
                         /* Fall through to add to randomness */
                 case IRQ_HANDLED:
                         status |= action->flags;