1 files changed, 55 insertions, 3 deletions

diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index 9ebf77968871..26e08754744f 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -17,6 +17,7 @@
 #include <linux/kernel_stat.h>
 #include <linux/rculist.h>
 #include <linux/hash.h>
+#include <trace/irq.h>
 #include <linux/bootmem.h>
 
 #include "internals.h"
@@ -338,6 +339,18 @@ 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);
+}
+
+DEFINE_TRACE(irq_handler_entry);
+DEFINE_TRACE(irq_handler_exit);
+
 /**
  * handle_IRQ_event - irq action chain handler
  * @irq:        the interrupt number
@@ -350,15 +363,54 @@ irqreturn_t handle_IRQ_event(unsigned int irq, struct irqaction *action)
         irqreturn_t ret, retval = IRQ_NONE;
         unsigned int status = 0;
 
-        WARN_ONCE(!in_irq(), "BUG: IRQ handler called from non-hardirq context!");
-
         if (!(action->flags & IRQF_DISABLED))
                 local_irq_enable_in_hardirq();
 
         do {
+                trace_irq_handler_entry(irq, action);
                 ret = action->handler(irq, action->dev_id);
-                if (ret == IRQ_HANDLED)
+                trace_irq_handler_exit(irq, action, ret);
+
+                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
+                         * interrupt. The hardirq handler above has
+                         * disabled the device interrupt, so no irq
+                         * storm is lurking.
+                         */
+                        if (likely(!test_bit(IRQTF_DIED,
+                                             &action->thread_flags))) {
+                                set_bit(IRQTF_RUNTHREAD, &action->thread_flags);
+                                wake_up_process(action->thread);
+                        }
+
+                        /* Fall through to add to randomness */
+                case IRQ_HANDLED:
                         status |= action->flags;
+                        break;
+
+                default:
+                        break;
+                }
+
                 retval |= ret;
                 action = action->next;
         } while (action);