1 files changed, 12 insertions, 1 deletions

diff --git a/arch/x86/kernel/io_apic.c b/arch/x86/kernel/io_apic.c
index 34c74cf5c244..7ca556690474 100644
--- a/arch/x86/kernel/io_apic.c
+++ b/arch/x86/kernel/io_apic.c
@@ -146,6 +146,12 @@ static void init_one_irq_cfg(struct irq_cfg *cfg)
 }
 
 static struct irq_cfg *irq_cfgx;
+
+/*
+ * Protect the irq_cfgx_free freelist:
+ */
+static DEFINE_SPINLOCK(irq_cfg_lock);
+
 #ifdef CONFIG_HAVE_SPARSE_IRQ
 static struct irq_cfg *irq_cfgx_free;
 #endif
@@ -213,8 +219,9 @@ static struct irq_cfg *irq_cfg(unsigned int irq)
 static struct irq_cfg *irq_cfg_alloc(unsigned int irq)
 {
         struct irq_cfg *cfg, *cfg_pri;
-        int i;
+        unsigned long flags;
         int count = 0;
+        int i;
 
         cfg_pri = cfg = irq_cfgx;
         while (cfg) {
@@ -226,6 +233,7 @@ static struct irq_cfg *irq_cfg_alloc(unsigned int irq)
                 count++;
         }
 
+        spin_lock_irqsave(&irq_cfg_lock, flags);
         if (!irq_cfgx_free) {
                 unsigned long phys;
                 unsigned long total_bytes;
@@ -263,6 +271,9 @@ static struct irq_cfg *irq_cfg_alloc(unsigned int irq)
         else
                 irq_cfgx = cfg;
         cfg->irq = irq;
+
+        spin_unlock_irqrestore(&irq_cfg_lock, flags);
+
         printk(KERN_DEBUG "found new irq_cfg for irq %d\n", cfg->irq);
 #ifdef CONFIG_HAVE_SPARSE_IRQ_DEBUG
         {