4 files changed, 85 insertions, 64 deletions

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 7de11bd64dfe..55d526c0eefd 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -290,7 +290,8 @@ static inline void mask_ack_irq(struct irq_desc *desc, int irq)
                 desc->chip->mask_ack(irq);
         else {
                 desc->chip->mask(irq);
-                desc->chip->ack(irq);
+                if (desc->chip->ack)
+                        desc->chip->ack(irq);
         }
 }
 
@@ -476,7 +477,8 @@ handle_edge_irq(unsigned int irq, struct irq_desc *desc)
         kstat_incr_irqs_this_cpu(irq, desc);
 
         /* Start handling the irq */
-        desc->chip->ack(irq);
+        if (desc->chip->ack)
+                desc->chip->ack(irq);
         desc = irq_remap_to_desc(irq, desc);
 
         /* Mark the IRQ currently in progress.*/
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index 3aba8d12f328..a2ee682bca2e 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -328,6 +328,8 @@ 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();
 
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 291f03664552..52ee17135092 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -389,9 +389,9 @@ int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
  * allocate special interrupts that are part of the architecture.
  */
 static int
-__setup_irq(unsigned int irq, struct irq_desc * desc, struct irqaction *new)
+__setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 {
-        struct irqaction *old, **p;
+        struct irqaction *old, **old_ptr;
         const char *old_name = NULL;
         unsigned long flags;
         int shared = 0;
@@ -423,8 +423,8 @@ __setup_irq(unsigned int irq, struct irq_desc * desc, struct irqaction *new)
          * The following block of code has to be executed atomically
          */
         spin_lock_irqsave(&desc->lock, flags);
-        p = &desc->action;
-        old = *p;
+        old_ptr = &desc->action;
+        old = *old_ptr;
         if (old) {
                 /*
                  * Can't share interrupts unless both agree to and are
@@ -447,8 +447,8 @@ __setup_irq(unsigned int irq, struct irq_desc * desc, struct irqaction *new)
 
                 /* add new interrupt at end of irq queue */
                 do {
-                        p = &old->next;
-                        old = *p;
+                        old_ptr = &old->next;
+                        old = *old_ptr;
                 } while (old);
                 shared = 1;
         }
@@ -499,7 +499,7 @@ __setup_irq(unsigned int irq, struct irq_desc * desc, struct irqaction *new)
                                 (int)(new->flags & IRQF_TRIGGER_MASK));
         }
 
-        *p = new;
+        *old_ptr = new;
 
         /* Reset broken irq detection when installing new handler */
         desc->irq_count = 0;
@@ -567,72 +567,76 @@ int setup_irq(unsigned int irq, struct irqaction *act)
 void free_irq(unsigned int irq, void *dev_id)
 {
         struct irq_desc *desc = irq_to_desc(irq);
-        struct irqaction **p;
+        struct irqaction *action, **action_ptr;
         unsigned long flags;
 
-        WARN_ON(in_interrupt());
+        WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
 
         if (!desc)
                 return;
 
         spin_lock_irqsave(&desc->lock, flags);
-        p = &desc->action;
+
+        /*
+         * There can be multiple actions per IRQ descriptor, find the right
+         * one based on the dev_id:
+         */
+        action_ptr = &desc->action;
         for (;;) {
-                struct irqaction *action = *p;
+                action = *action_ptr;
+
+                if (!action) {
+                        WARN(1, "Trying to free already-free IRQ %d\n", irq);
+                        spin_unlock_irqrestore(&desc->lock, flags);
 
-                if (action) {
-                        struct irqaction **pp = p;
+                        return;
+                }
 
-                        p = &action->next;
-                        if (action->dev_id != dev_id)
-                                continue;
+                if (action->dev_id == dev_id)
+                        break;
+                action_ptr = &action->next;
+        }
 
-                        /* Found it - now remove it from the list of entries */
-                        *pp = action->next;
+        /* Found it - now remove it from the list of entries: */
+        *action_ptr = action->next;
 
-                        /* Currently used only by UML, might disappear one day.*/
+        /* Currently used only by UML, might disappear one day: */
 #ifdef CONFIG_IRQ_RELEASE_METHOD
-                        if (desc->chip->release)
-                                desc->chip->release(irq, dev_id);
+        if (desc->chip->release)
+                desc->chip->release(irq, dev_id);
 #endif
 
-                        if (!desc->action) {
-                                desc->status |= IRQ_DISABLED;
-                                if (desc->chip->shutdown)
-                                        desc->chip->shutdown(irq);
-                                else
-                                        desc->chip->disable(irq);
-                        }
-                        spin_unlock_irqrestore(&desc->lock, flags);
-                        unregister_handler_proc(irq, action);
+        /* If this was the last handler, shut down the IRQ line: */
+        if (!desc->action) {
+                desc->status |= IRQ_DISABLED;
+                if (desc->chip->shutdown)
+                        desc->chip->shutdown(irq);
+                else
+                        desc->chip->disable(irq);
+        }
+        spin_unlock_irqrestore(&desc->lock, flags);
+
+        unregister_handler_proc(irq, action);
+
+        /* Make sure it's not being used on another CPU: */
+        synchronize_irq(irq);
 
-                        /* Make sure it's not being used on another CPU */
-                        synchronize_irq(irq);
-#ifdef CONFIG_DEBUG_SHIRQ
-                        /*
-                         * It's a shared IRQ -- the driver ought to be
-                         * prepared for it to happen even now it's
-                         * being freed, so let's make sure....  We do
-                         * this after actually deregistering it, to
-                         * make sure that a 'real' IRQ doesn't run in
-                         * parallel with our fake
-                         */
-                        if (action->flags & IRQF_SHARED) {
-                                local_irq_save(flags);
-                                action->handler(irq, dev_id);
-                                local_irq_restore(flags);
-                        }
-#endif
-                        kfree(action);
-                        return;
-                }
-                printk(KERN_ERR "Trying to free already-free IRQ %d\n", irq);
 #ifdef CONFIG_DEBUG_SHIRQ
-                dump_stack();
-#endif
-                spin_unlock_irqrestore(&desc->lock, flags);
-                return;
+        /*
+         * It's a shared IRQ -- the driver ought to be prepared for an IRQ
+         * event to happen even now it's being freed, so let's make sure that
+         * is so by doing an extra call to the handler ....
+         *
+         * ( We do this after actually deregistering it, to make sure that a
+         *   'real' IRQ doesn't run in * parallel with our fake. )
+         */
+        if (action->flags & IRQF_SHARED) {
+                local_irq_save(flags);
+                action->handler(irq, dev_id);
+                local_irq_restore(flags);
         }
+#endif
+        kfree(action);
 }
 EXPORT_SYMBOL(free_irq);
 
@@ -679,11 +683,12 @@ int request_irq(unsigned int irq, irq_handler_t handler,
          * the behavior is classified as "will not fix" so we need to
          * start nudging drivers away from using that idiom.
          */
-        if ((irqflags & (IRQF_SHARED|IRQF_DISABLED))
-                        == (IRQF_SHARED|IRQF_DISABLED))
-                pr_warning("IRQ %d/%s: IRQF_DISABLED is not "
-                                "guaranteed on shared IRQs\n",
-                                irq, devname);
+        if ((irqflags & (IRQF_SHARED|IRQF_DISABLED)) ==
+                                        (IRQF_SHARED|IRQF_DISABLED)) {
+                pr_warning(
+                  "IRQ %d/%s: IRQF_DISABLED is not guaranteed on shared IRQs\n",
+                        irq, devname);
+        }
 
 #ifdef CONFIG_LOCKDEP
         /*
@@ -709,7 +714,7 @@ int request_irq(unsigned int irq, irq_handler_t handler,
         if (!handler)
                 return -EINVAL;
 
-        action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
+        action = kmalloc(sizeof(struct irqaction), GFP_KERNEL);
         if (!action)
                 return -ENOMEM;
 
diff --git a/kernel/irq/spurious.c b/kernel/irq/spurious.c
index dd364c11e56e..4d568294de3e 100644
--- a/kernel/irq/spurious.c
+++ b/kernel/irq/spurious.c
@@ -104,7 +104,7 @@ static int misrouted_irq(int irq)
         return ok;
 }
 
-static void poll_spurious_irqs(unsigned long dummy)
+static void poll_all_shared_irqs(void)
 {
         struct irq_desc *desc;
         int i;
@@ -123,11 +123,23 @@ static void poll_spurious_irqs(unsigned long dummy)
 
                 try_one_irq(i, desc);
         }
+}
+
+static void poll_spurious_irqs(unsigned long dummy)
+{
+        poll_all_shared_irqs();
 
         mod_timer(&poll_spurious_irq_timer,
                   jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
 }
 
+#ifdef CONFIG_DEBUG_SHIRQ
+void debug_poll_all_shared_irqs(void)
+{
+        poll_all_shared_irqs();
+}
+#endif
+
 /*
  * If 99,900 of the previous 100,000 interrupts have not been handled
  * then assume that the IRQ is stuck in some manner. Drop a diagnostic