x86: sparse_irq needs spin_lock in allocations

Suresh Siddha noticed that we should have a spinlock around it.

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 12 insertions, 1 deletions

diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index 24c83a3cee4d..d638a911cbc1 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -107,6 +107,11 @@ static void init_kstat_irqs(struct irq_desc *desc, int nr_desc, int nr)
         }
 }
 
+/*
+ * Protect the sparse_irqs_free freelist:
+ */
+static DEFINE_SPINLOCK(sparse_irq_lock);
+
 #ifdef CONFIG_HAVE_SPARSE_IRQ
 static struct irq_desc *sparse_irqs_free;
 struct irq_desc *sparse_irqs;
@@ -166,11 +171,13 @@ struct irq_desc *irq_to_desc(unsigned int irq)
         }
         return NULL;
 }
+
 struct irq_desc *irq_to_desc_alloc(unsigned int irq)
 {
         struct irq_desc *desc, *desc_pri;
-        int i;
+        unsigned long flags;
         int count = 0;
+        int i;
 
         desc_pri = desc = sparse_irqs;
         while (desc) {
@@ -182,6 +189,7 @@ struct irq_desc *irq_to_desc_alloc(unsigned int irq)
                 count++;
         }
 
+        spin_lock_irqsave(&sparse_irq_lock, flags);
         /*
          *  we run out of pre-allocate ones, allocate more
          */
@@ -223,6 +231,9 @@ struct irq_desc *irq_to_desc_alloc(unsigned int irq)
         else
                 sparse_irqs = desc;
         desc->irq = irq;
+
+        spin_unlock_irqrestore(&sparse_irq_lock, flags);
+
         printk(KERN_DEBUG "found new irq_desc for irq %d\n", desc->irq);
 #ifdef CONFIG_HAVE_SPARSE_IRQ_DEBUG
         {