irq: add remove_irq() for freeing of setup_irq() irqs

Impact: add new API

This patch adds a remove_irq() function for releasing
interrupts requested with setup_irq().

Without this patch we have no way of releasing such
interrupts since free_irq() today tries to kfree()
the irqaction passed with setup_irq().

Signed-off-by: Magnus Damm <damm@igel.co.jp>
LKML-Reference: <20090312120542.2926.56609.sendpatchset@rx1.opensource.se>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 27 insertions, 13 deletions

diff --git a/include/linux/irq.h b/include/linux/irq.h
index f899b502f186..56f9988362ec 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -236,6 +236,7 @@ typedef struct irq_desc		irq_desc_t;
 #include <asm/hw_irq.h>
 
 extern int setup_irq(unsigned int irq, struct irqaction *new);
+extern struct irqaction *remove_irq(unsigned int irq, void *dev_id);
 
 #ifdef CONFIG_GENERIC_HARDIRQS
 
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 52ee17135092..8b069a7046e9 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -551,20 +551,14 @@ int setup_irq(unsigned int irq, struct irqaction *act)
 }
 
 /**
- *      free_irq - free an interrupt
+ *      remove_irq - free an interrupt
  *      @irq: Interrupt line to free
  *      @dev_id: Device identity to free
  *
- *      Remove an interrupt handler. The handler is removed and if the
- *      interrupt line is no longer in use by any driver it is disabled.
- *      On a shared IRQ the caller must ensure the interrupt is disabled
- *      on the card it drives before calling this function. The function
- *      does not return until any executing interrupts for this IRQ
- *      have completed.
- *
- *      This function must not be called from interrupt context.
+ * Used to remove interrupts statically setup by the early boot process.
  */
-void free_irq(unsigned int irq, void *dev_id)
+
+struct irqaction *remove_irq(unsigned int irq, void *dev_id)
 {
         struct irq_desc *desc = irq_to_desc(irq);
         struct irqaction *action, **action_ptr;
@@ -573,7 +567,7 @@ void free_irq(unsigned int irq, void *dev_id)
         WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
 
         if (!desc)
-                return;
+                return NULL;
 
         spin_lock_irqsave(&desc->lock, flags);
 
@@ -589,7 +583,7 @@ void free_irq(unsigned int irq, void *dev_id)
                         WARN(1, "Trying to free already-free IRQ %d\n", irq);
                         spin_unlock_irqrestore(&desc->lock, flags);
 
-                        return;
+                        return NULL;
                 }
 
                 if (action->dev_id == dev_id)
@@ -636,7 +630,26 @@ void free_irq(unsigned int irq, void *dev_id)
                 local_irq_restore(flags);
         }
 #endif
-        kfree(action);
+        return action;
+}
+
+/**
+ *      free_irq - free an interrupt allocated with request_irq
+ *      @irq: Interrupt line to free
+ *      @dev_id: Device identity to free
+ *
+ *      Remove an interrupt handler. The handler is removed and if the
+ *      interrupt line is no longer in use by any driver it is disabled.
+ *      On a shared IRQ the caller must ensure the interrupt is disabled
+ *      on the card it drives before calling this function. The function
+ *      does not return until any executing interrupts for this IRQ
+ *      have completed.
+ *
+ *      This function must not be called from interrupt context.
+ */
+void free_irq(unsigned int irq, void *dev_id)
+{
+        kfree(remove_irq(irq, dev_id));
 }
 EXPORT_SYMBOL(free_irq);