diff --git a/drivers/char/nwflash.c b/drivers/char/nwflash.c
index 043a1c7..a12f524 100644
--- a/drivers/char/nwflash.c
+++ b/drivers/char/nwflash.c
@@ -25,7 +25,6 @@
 #include <linux/spinlock.h>
 #include <linux/rwsem.h>
 #include <linux/init.h>
-#include <linux/smp_lock.h>
 #include <linux/mutex.h>
 #include <linux/jiffies.h>
 
@@ -41,6 +40,7 @@
 
 #define	NWFLASH_VERSION "6.4"
 
+static DEFINE_MUTEX(flash_mutex);
 static void kick_open(void);
 static int get_flash_id(void);
 static int erase_block(int nBlock);
@@ -96,7 +96,7 @@
 
 static long flash_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
 {
-	lock_kernel();
+	mutex_lock(&flash_mutex);
 	switch (cmd) {
 	case CMD_WRITE_DISABLE:
 		gbWriteBase64Enable = 0;
@@ -114,10 +114,10 @@
 	default:
 		gbWriteBase64Enable = 0;
 		gbWriteEnable = 0;
-		unlock_kernel();
+		mutex_unlock(&flash_mutex);
 		return -EINVAL;
 	}
-	unlock_kernel();
+	mutex_unlock(&flash_mutex);
 	return 0;
 }
 
@@ -282,7 +282,7 @@
 {
 	loff_t ret;
 
-	lock_kernel();
+	mutex_lock(&flash_mutex);
 	if (flashdebug)
 		printk(KERN_DEBUG "flash_llseek: offset=0x%X, orig=0x%X.\n",
 		       (unsigned int) offset, orig);
@@ -317,7 +317,7 @@
 	default:
 		ret = -EINVAL;
 	}
-	unlock_kernel();
+	mutex_unlock(&flash_mutex);
 	return ret;
 }