Merge branch 'perf/urgent' into perf/core

Conflicts:
	arch/x86/kernel/cpu/perf_event.c

Merge reason: Resolve the conflict, pick up fixes

Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 22 insertions, 0 deletions

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index eb6078ca60c7..398fda155f6e 100644
--- 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);