diff --git a/[refs] b/[refs]
index b8303d961b19..5357b5f1296c 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 6044c319d11051f3462dafd0e7a900ef121d7bc7
+refs/heads/master: b691750098f830b748540cd955f5ac56545bab25
diff --git a/trunk/arch/parisc/kernel/perf.c b/trunk/arch/parisc/kernel/perf.c
index 89d6d5ad44b5..f696f57faa15 100644
--- a/trunk/arch/parisc/kernel/perf.c
+++ b/trunk/arch/parisc/kernel/perf.c
@@ -46,6 +46,7 @@
 #include <linux/init.h>
 #include <linux/proc_fs.h>
 #include <linux/miscdevice.h>
+#include <linux/smp_lock.h>
 #include <linux/spinlock.h>
 
 #include <asm/uaccess.h>
@@ -260,13 +261,16 @@ printk("Preparing to start counters\n");
  */
 static int perf_open(struct inode *inode, struct file *file)
 {
+	lock_kernel();
 	spin_lock(&perf_lock);
 	if (perf_enabled) {
 		spin_unlock(&perf_lock);
+		unlock_kernel();
 		return -EBUSY;
 	}
 	perf_enabled = 1;
  	spin_unlock(&perf_lock);
+	unlock_kernel();
 
 	return 0;
 }