[PATCH] use mutex instead of semaphore in virtual console driver

[Matthias Kaehlcke <matthias.kaehlcke@gmail.com>]

the virtual console driver uses a semaphore as mutex. use the mutex
API instead of the (binary) semaphore

Signed-off-by: Matthias Kaehlcke <matthias.kaehlcke@gmail.com>

--
diff --git a/drivers/char/vc_screen.c b/drivers/char/vc_screen.c
index 7919303..032d4f1 100644
--- a/drivers/char/vc_screen.c
+++ b/drivers/char/vc_screen.c
@@ -70,11 +70,11 @@ static loff_t vcs_lseek(struct file *file, loff_t offset, int orig)
 {
 	int size;
 
-	down(&con_buf_sem);
+	mutex_lock(&con_buf_mtx);
 	size = vcs_size(file->f_path.dentry->d_inode);
 	switch (orig) {
 		default:
-			up(&con_buf_sem);
+			mutex_unlock(&con_buf_mtx);
 			return -EINVAL;
 		case 2:
 			offset += size;
@@ -85,11 +85,11 @@ static loff_t vcs_lseek(struct file *file, loff_t offset, int orig)
 			break;
 	}
 	if (offset < 0 || offset > size) {
-		up(&con_buf_sem);
+		mutex_unlock(&con_buf_mtx);
 		return -EINVAL;
 	}
 	file->f_pos = offset;
-	up(&con_buf_sem);
+	mutex_unlock(&con_buf_mtx);
 	return file->f_pos;
 }
 
@@ -106,7 +106,7 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 	unsigned short *org = NULL;
 	ssize_t ret;
 
-	down(&con_buf_sem);
+	mutex_lock(&con_buf_mtx);
 
 	pos = *ppos;
 
@@ -263,7 +263,7 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 		ret = read;
 unlock_out:
 	release_console_sem();
-	up(&con_buf_sem);
+	mutex_unlock(&con_buf_mtx);
 	return ret;
 }
 
@@ -280,7 +280,7 @@ vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 	u16 *org0 = NULL, *org = NULL;
 	size_t ret;
 
-	down(&con_buf_sem);
+	mutex_lock(&con_buf_mtx);
 
 	pos = *ppos;
 
@@ -450,7 +450,7 @@ vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 unlock_out:
 	release_console_sem();
 
-	up(&con_buf_sem);
+	mutex_unlock(&con_buf_mtx);
 
 	return ret;
 }
diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index 1bbb45b..497d24c 100644
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -1930,7 +1930,7 @@ static void do_con_trol(struct tty_struct *tty, struct vc_data *vc, int c)
  * kernel memory allocation is available.
  */
 char con_buf[CON_BUF_SIZE];
-DECLARE_MUTEX(con_buf_sem);
+DEFINE_MUTEX(con_buf_mtx);
 
 /* acquires console_sem */
 static int do_con_write(struct tty_struct *tty, const unsigned char *buf, int count)
@@ -1983,7 +1983,7 @@ static int do_con_write(struct tty_struct *tty, const unsigned char *buf, int co
 
 	/* At this point 'buf' is guaranteed to be a kernel buffer
 	 * and therefore no access to userspace (and therefore sleeping)
-	 * will be needed.  The con_buf_sem serializes all tty based
+	 * will be needed.  The con_buf_mtx serializes all tty based
 	 * console rendering and vcs write/read operations.  We hold
 	 * the console spinlock during the entire write.
 	 */
diff --git a/include/linux/vt_kern.h b/include/linux/vt_kern.h
index e0db669..146dbca 100644
--- a/include/linux/vt_kern.h
+++ b/include/linux/vt_kern.h
@@ -82,7 +82,7 @@ void reset_vc(struct vc_data *vc);
 
 #define CON_BUF_SIZE (CONFIG_BASE_SMALL ? 256 : PAGE_SIZE)
 extern char con_buf[CON_BUF_SIZE];
-extern struct semaphore con_buf_sem;
+extern struct mutex con_buf_mtx;
 extern char vt_dont_switch;
 
 struct vt_spawn_console {

-- 
Matthias Kaehlcke
Linux Application Developer
Barcelona

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    ne me demande que je suis, d'où je viens et ce que je fais
                              (B. Traven)
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