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>

3 files changed, 33 insertions, 15 deletions

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index dbf6a6fd116c..266a5f5f57cc 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -63,10 +63,12 @@
  * Bits used by threaded handlers:
  * IRQTF_RUNTHREAD - signals that the interrupt handler thread should run
  * IRQTF_DIED      - handler thread died
+ * IRQTF_WARNED    - warning "IRQ_WAKE_THREAD w/o thread_fn" has been printed
  */
 enum {
         IRQTF_RUNTHREAD,
         IRQTF_DIED,
+        IRQTF_WARNED,
 };
 
 typedef irqreturn_t (*irq_handler_t)(int, void *);
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;
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index a4c1ab86cd25..a3eb7baf1e46 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -407,20 +407,17 @@ int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
         return ret;
 }
 
-static inline int irq_thread_should_run(struct irqaction *action)
-{
-        return test_and_clear_bit(IRQTF_RUNTHREAD, &action->thread_flags);
-}
-
 static int irq_wait_for_interrupt(struct irqaction *action)
 {
         while (!kthread_should_stop()) {
                 set_current_state(TASK_INTERRUPTIBLE);
-                if (irq_thread_should_run(action)) {
+
+                if (test_and_clear_bit(IRQTF_RUNTHREAD,
+                                       &action->thread_flags)) {
                         __set_current_state(TASK_RUNNING);
                         return 0;
-                } else
-                        schedule();
+                }
+                schedule();
         }
         return -1;
 }
@@ -820,8 +817,8 @@ EXPORT_SYMBOL(free_irq);
  *      @irq: Interrupt line to allocate
  *      @handler: Function to be called when the IRQ occurs.
  *                Primary handler for threaded interrupts
- *      @thread_fn: Function called from the irq handler thread
- *                  If NULL, no irq thread is created
+ *      @thread_fn: Function called from the irq handler thread
+ *                  If NULL, no irq thread is created
  *      @irqflags: Interrupt type flags
  *      @devname: An ascii name for the claiming device
  *      @dev_id: A cookie passed back to the handler function