Merge branch 'irq-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'irq-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  genirq: Move two IRQ functions from .init.text to .text
  genirq: Protect access to irq_desc->action in can_request_irq()
  genirq: Prevent oneshot irq thread race

2 files changed, 46 insertions, 11 deletions

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 42ec11b2af8a..b7091d5ca2f8 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -359,6 +359,23 @@ static inline void mask_ack_irq(struct irq_desc *desc, int irq)
                 if (desc->chip->ack)
                         desc->chip->ack(irq);
         }
+        desc->status |= IRQ_MASKED;
+}
+
+static inline void mask_irq(struct irq_desc *desc, int irq)
+{
+        if (desc->chip->mask) {
+                desc->chip->mask(irq);
+                desc->status |= IRQ_MASKED;
+        }
+}
+
+static inline void unmask_irq(struct irq_desc *desc, int irq)
+{
+        if (desc->chip->unmask) {
+                desc->chip->unmask(irq);
+                desc->status &= ~IRQ_MASKED;
+        }
 }
 
 /*
@@ -484,10 +501,8 @@ handle_level_irq(unsigned int irq, struct irq_desc *desc)
         raw_spin_lock(&desc->lock);
         desc->status &= ~IRQ_INPROGRESS;
 
-        if (unlikely(desc->status & IRQ_ONESHOT))
-                desc->status |= IRQ_MASKED;
-        else if (!(desc->status & IRQ_DISABLED) && desc->chip->unmask)
-                desc->chip->unmask(irq);
+        if (!(desc->status & (IRQ_DISABLED | IRQ_ONESHOT)))
+                unmask_irq(desc, irq);
 out_unlock:
         raw_spin_unlock(&desc->lock);
 }
@@ -524,8 +539,7 @@ handle_fasteoi_irq(unsigned int irq, struct irq_desc *desc)
         action = desc->action;
         if (unlikely(!action || (desc->status & IRQ_DISABLED))) {
                 desc->status |= IRQ_PENDING;
-                if (desc->chip->mask)
-                        desc->chip->mask(irq);
+                mask_irq(desc, irq);
                 goto out;
         }
 
@@ -593,7 +607,7 @@ handle_edge_irq(unsigned int irq, struct irq_desc *desc)
                 irqreturn_t action_ret;
 
                 if (unlikely(!action)) {
-                        desc->chip->mask(irq);
+                        mask_irq(desc, irq);
                         goto out_unlock;
                 }
 
@@ -605,8 +619,7 @@ handle_edge_irq(unsigned int irq, struct irq_desc *desc)
                 if (unlikely((desc->status &
                                (IRQ_PENDING | IRQ_MASKED | IRQ_DISABLED)) ==
                               (IRQ_PENDING | IRQ_MASKED))) {
-                        desc->chip->unmask(irq);
-                        desc->status &= ~IRQ_MASKED;
+                        unmask_irq(desc, irq);
                 }
 
                 desc->status &= ~IRQ_PENDING;
@@ -716,7 +729,7 @@ set_irq_chip_and_handler_name(unsigned int irq, struct irq_chip *chip,
         __set_irq_handler(irq, handle, 0, name);
 }
 
-void __init set_irq_noprobe(unsigned int irq)
+void set_irq_noprobe(unsigned int irq)
 {
         struct irq_desc *desc = irq_to_desc(irq);
         unsigned long flags;
@@ -731,7 +744,7 @@ void __init set_irq_noprobe(unsigned int irq)
         raw_spin_unlock_irqrestore(&desc->lock, flags);
 }
 
-void __init set_irq_probe(unsigned int irq)
+void set_irq_probe(unsigned int irq)
 {
         struct irq_desc *desc = irq_to_desc(irq);
         unsigned long flags;
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);