1 files changed, 17 insertions, 8 deletions

diff --git a/arch/x86/kernel/cpuid.c b/arch/x86/kernel/cpuid.c
index daff52a62248..71f1c2654bec 100644
--- a/arch/x86/kernel/cpuid.c
+++ b/arch/x86/kernel/cpuid.c
@@ -33,6 +33,7 @@
 #include <linux/init.h>
 #include <linux/poll.h>
 #include <linux/smp.h>
+#include <linux/smp_lock.h>
 #include <linux/major.h>
 #include <linux/fs.h>
 #include <linux/smp_lock.h>
@@ -107,15 +108,23 @@ static ssize_t cpuid_read(struct file *file, char __user *buf,
 
 static int cpuid_open(struct inode *inode, struct file *file)
 {
-        unsigned int cpu = iminor(file->f_path.dentry->d_inode);
-        struct cpuinfo_x86 *c = &cpu_data(cpu);
-
-        if (cpu >= NR_CPUS || !cpu_online(cpu))
-                return -ENXIO;  /* No such CPU */
+        unsigned int cpu;
+        struct cpuinfo_x86 *c;
+        int ret = 0;
+        
+        lock_kernel();
+
+        cpu = iminor(file->f_path.dentry->d_inode);
+        if (cpu >= NR_CPUS || !cpu_online(cpu)) {
+                ret = -ENXIO;   /* No such CPU */
+                goto out;
+        }
+        c = &cpu_data(cpu);
         if (c->cpuid_level < 0)
-                return -EIO;    /* CPUID not supported */
-
-        return 0;
+                ret = -EIO;     /* CPUID not supported */
+out:
+        unlock_kernel();
+        return ret;
 }
 
 /*