3 files changed, 35 insertions, 19 deletions

diff --git a/include/linux/irq.h b/include/linux/irq.h
index 1883a85625dd..552e0ec269c9 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -61,6 +61,7 @@ typedef	void (*irq_flow_handler_t)(unsigned int irq,
 #define IRQ_WAKEUP              0x00100000      /* IRQ triggers system wakeup */
 #define IRQ_MOVE_PENDING        0x00200000      /* need to re-target IRQ destination */
 #define IRQ_NO_BALANCING        0x00400000      /* IRQ is excluded from balancing */
+#define IRQ_SPURIOUS_DISABLED   0x00800000      /* IRQ was disabled by the spurious trap */
 
 #ifdef CONFIG_IRQ_PER_CPU
 # define CHECK_IRQ_PER_CPU(var) ((var) & IRQ_PER_CPU)
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 46e4ad1723f0..46d6611a33bb 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -150,6 +150,26 @@ void disable_irq(unsigned int irq)
 }
 EXPORT_SYMBOL(disable_irq);
 
+static void __enable_irq(struct irq_desc *desc, unsigned int irq)
+{
+        switch (desc->depth) {
+        case 0:
+                printk(KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
+                WARN_ON(1);
+                break;
+        case 1: {
+                unsigned int status = desc->status & ~IRQ_DISABLED;
+
+                /* Prevent probing on this irq: */
+                desc->status = status | IRQ_NOPROBE;
+                check_irq_resend(desc, irq);
+                /* fall-through */
+        }
+        default:
+                desc->depth--;
+        }
+}
+
 /**
  *      enable_irq - enable handling of an irq
  *      @irq: Interrupt to enable
@@ -169,22 +189,7 @@ void enable_irq(unsigned int irq)
                 return;
 
         spin_lock_irqsave(&desc->lock, flags);
-        switch (desc->depth) {
-        case 0:
-                printk(KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
-                WARN_ON(1);
-                break;
-        case 1: {
-                unsigned int status = desc->status & ~IRQ_DISABLED;
-
-                /* Prevent probing on this irq: */
-                desc->status = status | IRQ_NOPROBE;
-                check_irq_resend(desc, irq);
-                /* fall-through */
-        }
-        default:
-                desc->depth--;
-        }
+        __enable_irq(desc, irq);
         spin_unlock_irqrestore(&desc->lock, flags);
 }
 EXPORT_SYMBOL(enable_irq);
@@ -365,7 +370,7 @@ int setup_irq(unsigned int irq, struct irqaction *new)
                         compat_irq_chip_set_default_handler(desc);
 
                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
-                                  IRQ_INPROGRESS);
+                                  IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
 
                 if (!(desc->status & IRQ_NOAUTOEN)) {
                         desc->depth = 0;
@@ -381,6 +386,16 @@ int setup_irq(unsigned int irq, struct irqaction *new)
         /* Reset broken irq detection when installing new handler */
         desc->irq_count = 0;
         desc->irqs_unhandled = 0;
+
+        /*
+         * Check whether we disabled the irq via the spurious handler
+         * before. Reenable it and give it another chance.
+         */
+        if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
+                desc->status &= ~IRQ_SPURIOUS_DISABLED;
+                __enable_irq(desc, irq);
+        }
+
         spin_unlock_irqrestore(&desc->lock, flags);
 
         new->irq = irq;
diff --git a/kernel/irq/spurious.c b/kernel/irq/spurious.c
index 088dabbf2d6a..c66d3f10e853 100644
--- a/kernel/irq/spurious.c
+++ b/kernel/irq/spurious.c
@@ -209,8 +209,8 @@ void note_interrupt(unsigned int irq, struct irq_desc *desc,
                  * Now kill the IRQ
                  */
                 printk(KERN_EMERG "Disabling IRQ #%d\n", irq);
-                desc->status |= IRQ_DISABLED;
-                desc->depth = 1;
+                desc->status |= IRQ_DISABLED | IRQ_SPURIOUS_DISABLED;
+                desc->depth++;
                 desc->chip->disable(irq);
         }
         desc->irqs_unhandled = 0;