1 files changed, 17 insertions, 2 deletions

diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index e3a8c9577ba6..a50ddc9417ff 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -12,6 +12,7 @@
 #include <linux/seq_file.h>
 #include <linux/interrupt.h>
 #include <linux/kernel_stat.h>
+#include <linux/mutex.h>
 
 #include "internals.h"
 
@@ -323,18 +324,29 @@ void register_handler_proc(unsigned int irq, struct irqaction *action)
 
 void register_irq_proc(unsigned int irq, struct irq_desc *desc)
 {
+        static DEFINE_MUTEX(register_lock);
         char name [MAX_NAMELEN];
 
-        if (!root_irq_dir || (desc->irq_data.chip == &no_irq_chip) || desc->dir)
+        if (!root_irq_dir || (desc->irq_data.chip == &no_irq_chip))
                 return;
 
+        /*
+         * irq directories are registered only when a handler is
+         * added, not when the descriptor is created, so multiple
+         * tasks might try to register at the same time.
+         */
+        mutex_lock(&register_lock);
+
+        if (desc->dir)
+                goto out_unlock;
+
         memset(name, 0, MAX_NAMELEN);
         sprintf(name, "%d", irq);
 
         /* create /proc/irq/1234 */
         desc->dir = proc_mkdir(name, root_irq_dir);
         if (!desc->dir)
-                return;
+                goto out_unlock;
 
 #ifdef CONFIG_SMP
         /* create /proc/irq/<irq>/smp_affinity */
@@ -355,6 +367,9 @@ void register_irq_proc(unsigned int irq, struct irq_desc *desc)
 
         proc_create_data("spurious", 0444, desc->dir,
                          &irq_spurious_proc_fops, (void *)(long)irq);
+
+out_unlock:
+        mutex_unlock(&register_lock);
 }
 
 void unregister_irq_proc(unsigned int irq, struct irq_desc *desc)