Merge branch 'merge' of git://git.secretlab.ca/git/linux-2.6

[linux-2.6-block.git] / kernel / irq / manage.c

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index eb6078ca60c7f548a052aa42c247dbb8b24d9620..398fda155f6e26dd72dd1fa00805b1383c156a5d 100644 (file)
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -382,6 +382,7 @@ int can_request_irq(unsigned int irq, unsigned long irqflags)
 {
        struct irq_desc *desc = irq_to_desc(irq);
        struct irqaction *action;
+       unsigned long flags;
 
        if (!desc)
                return 0;
@@ -389,11 +390,14 @@ int can_request_irq(unsigned int irq, unsigned long irqflags)
        if (desc->status & IRQ_NOREQUEST)
                return 0;
 
+       raw_spin_lock_irqsave(&desc->lock, flags);
        action = desc->action;
        if (action)
                if (irqflags & action->flags & IRQF_SHARED)
                        action = NULL;
 
+       raw_spin_unlock_irqrestore(&desc->lock, flags);
+
        return !action;
 }
 
@@ -483,8 +487,26 @@ static int irq_wait_for_interrupt(struct irqaction *action)
  */
 static void irq_finalize_oneshot(unsigned int irq, struct irq_desc *desc)
 {
+again:
        chip_bus_lock(irq, desc);
        raw_spin_lock_irq(&desc->lock);
+
+       /*
+        * Implausible though it may be we need to protect us against
+        * the following scenario:
+        *
+        * The thread is faster done than the hard interrupt handler
+        * on the other CPU. If we unmask the irq line then the
+        * interrupt can come in again and masks the line, leaves due
+        * to IRQ_INPROGRESS and the irq line is masked forever.
+        */
+       if (unlikely(desc->status & IRQ_INPROGRESS)) {
+               raw_spin_unlock_irq(&desc->lock);
+               chip_bus_sync_unlock(irq, desc);
+               cpu_relax();
+               goto again;
+       }
+
        if (!(desc->status & IRQ_DISABLED) && (desc->status & IRQ_MASKED)) {
                desc->status &= ~IRQ_MASKED;
                desc->chip->unmask(irq);