[PATCH for-4.5 7/8] xen/irq: Handle multiple action per IRQ

[Julien Grall <julien.grall@linaro.org>]

On ARM, it may happen (eg ARM SMMU) to setup multiple handler for the same
interrupt.

Signed-off-by: Julien Grall <julien.grall@linaro.org>
CC: Keir Fraser <keir@xen.org>
---
 xen/arch/arm/gic.c    |   48 ++++++++++++++++++++++++++++++++++++++++--------
 xen/arch/arm/irq.c    |    6 +++++-
 xen/include/xen/irq.h |    1 +
 3 files changed, 46 insertions(+), 9 deletions(-)

diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
index ebd2b5f..8ba1de3 100644
--- a/xen/arch/arm/gic.c
+++ b/xen/arch/arm/gic.c
@@ -534,32 +534,64 @@ void release_dt_irq(const struct dt_irq *irq, const void *dev_id)
 {
     struct irq_desc *desc;
     unsigned long flags;
-   struct irqaction *action;
+    struct irqaction *action, **action_ptr;
 
     desc = irq_to_desc(irq->irq);
 
     spin_lock_irqsave(&desc->lock,flags);
     desc->handler->shutdown(desc);
     action = desc->action;
-    desc->action  = NULL;
-    desc->status &= ~IRQ_GUEST;
+
+    action_ptr = &desc->action;
+    for ( ;; )
+    {
+        action = *action_ptr;
+
+        if ( !action )
+        {
+            printk(XENLOG_WARNING "Trying to free already-free IRQ %u\n",
+                   irq->irq);
+            return;
+        }
+
+        if ( action->dev_id == dev_id )
+            break;
+
+        action_ptr = &action->next;
+    }
+
+    /* Found it - remove it from the action list */
+    *action_ptr = action->next;
+
+    /* If this was the list action, shut down the IRQ */
+    if ( !desc->action )
+    {
+        desc->handler->shutdown(desc);
+        desc->status &= ~IRQ_GUEST;
+    }
 
     spin_unlock_irqrestore(&desc->lock,flags);
 
     /* Wait to make sure it's not being used on another CPU */
     do { smp_mb(); } while ( desc->status & IRQ_INPROGRESS );
 
-    if (action && action->free_on_release)
+    if ( action && action->free_on_release )
         xfree(action);
 }
 
 static int __setup_irq(struct irq_desc *desc, unsigned int irq,
                        struct irqaction *new)
 {
-    if ( desc->action != NULL )
-        return -EBUSY;
+    struct irqaction *action = desc->action;
+
+    ASSERT(new != NULL);
+
+    /* Check that dev_id is correctly filled if we have multiple action */
+    if ( action != NULL && ( action->dev_id == NULL || new->dev_id == NULL ) )
+        return -EINVAL;
 
-    desc->action  = new;
+    new->next = desc->action;
+    desc->action = new;
     dsb();
 
     return 0;
@@ -610,7 +642,7 @@ int __init setup_dt_irq(const struct dt_irq *irq, struct irqaction *new)
 
     rc = __setup_irq(desc, irq->irq, new);
 
-    if ( !rc )
+    if ( !rc && disabled )
         desc->handler->startup(desc);
 
     spin_unlock_irqrestore(&desc->lock, flags);
diff --git a/xen/arch/arm/irq.c b/xen/arch/arm/irq.c
index 3e326b0..edf0404 100644
--- a/xen/arch/arm/irq.c
+++ b/xen/arch/arm/irq.c
@@ -179,7 +179,11 @@ void do_IRQ(struct cpu_user_regs *regs, unsigned int irq, int is_fiq)
     {
         desc->status &= ~IRQ_PENDING;
         spin_unlock_irq(&desc->lock);
-        action->handler(irq, action->dev_id, regs);
+        do
+        {
+            action->handler(irq, action->dev_id, regs);
+            action = action->next;
+        } while ( action );
         spin_lock_irq(&desc->lock);
     }
 
diff --git a/xen/include/xen/irq.h b/xen/include/xen/irq.h
index f2e6215..54314b8 100644
--- a/xen/include/xen/irq.h
+++ b/xen/include/xen/irq.h
@@ -11,6 +11,7 @@
 
 struct irqaction {
     void (*handler)(int, void *, struct cpu_user_regs *);
+    struct irqaction *next;
     const char *name;
     void *dev_id;
     bool_t free_on_release;
-- 
1.7.10.4