From 342d263173687df5085816d9be0423023cd44cf6 Mon Sep 17 00:00:00 2001
From: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
Date: Thu, 20 May 2010 10:24:20 -0400
Subject: [PATCH] Use mutex.

---
 hellochar.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/hellochar.c b/hellochar.c
index 628f53c..1b0c9f2 100644
--- a/hellochar.c
+++ b/hellochar.c
@@ -20,7 +20,7 @@
 #include <linux/fs.h>
 #include <linux/cdev.h>
 #include <linux/slab.h>
-#include <linux/semaphore.h>
+#include <linux/mutex.h>
 #include <asm/uaccess.h>
 
 MODULE_LICENSE("GPL");
@@ -35,11 +35,11 @@ struct hello_buffer {
 	char buffer[0];
 };
 static struct hello_buffer *hello;
-static DECLARE_MUTEX(hello_mtx);
+static DEFINE_MUTEX(hello_mtx);
 
 static int hello_open(struct inode *ino, struct file *fp)
 {
-	if (down_interruptible(&hello_mtx))
+	if (mutex_lock_interruptible(&hello_mtx))
 		return -ERESTARTSYS;
 	if (fp->f_flags & O_TRUNC) {
 		memset(hello->buffer, 0, MAXLEN);
@@ -47,7 +47,7 @@ static int hello_open(struct inode *ino, struct file *fp)
 	}
 	if (fp->f_flags & O_APPEND)
 		fp->f_pos = hello->len;
-	up(&hello_mtx);
+	mutex_unlock(&hello_mtx);
 	return 0;
 }
 
@@ -55,12 +55,12 @@ static ssize_t hello_read(struct file *fp, char __user *buf, size_t sz,
 	loff_t *pos)
 {
 	int r;
-	if (down_interruptible(&hello_mtx))
+	if (mutex_lock_interruptible(&hello_mtx))
 		return -ERESTARTSYS;
 	if (sz + *pos > hello->len)
 		sz = hello->len - *pos;
 	r = copy_to_user(buf, hello->buffer + *pos, sz);
-	up(&hello_mtx);
+	mutex_unlock(&hello_mtx);
 	if (r)
 		return -EFAULT;
 	*pos += sz;
@@ -71,19 +71,19 @@ static ssize_t hello_write(struct file *fp, const char __user *buf, size_t sz,
 	loff_t *pos)
 {
 	int r;
-	if (down_interruptible(&hello_mtx))
+	if (mutex_lock_interruptible(&hello_mtx))
 		return -ERESTARTSYS;
 	if (sz + *pos > MAXLEN)
 		sz = MAXLEN - *pos;
 	r = copy_from_user(hello->buffer + *pos, buf, sz);
 	if (r) {
-		up(&hello_mtx);
+		mutex_unlock(&hello_mtx);
 		return -EFAULT;
 	}
 	*pos += sz;
 	if (hello->len < *pos)
 		hello->len = *pos;
-	up(&hello_mtx);
+	mutex_unlock(&hello_mtx);
 	return sz;
 }
 
-- 
2.20.1