From: Andrew Morton <akpm@linux-foundation.org>

Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/devpts/inode.c |   15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff -puN fs/devpts/inode.c~devpts-factor-out-pty-index-allocation-fix fs/devpts/inode.c
--- a/fs/devpts/inode.c~devpts-factor-out-pty-index-allocation-fix
+++ a/fs/devpts/inode.c
@@ -17,6 +17,7 @@
 #include <linux/namei.h>
 #include <linux/mount.h>
 #include <linux/tty.h>
+#include <linux/mutex.h>
 #include <linux/idr.h>
 #include <linux/devpts_fs.h>
 #include <linux/parser.h>
@@ -29,7 +30,7 @@
 
 extern int pty_limit;			/* Config limit on Unix98 ptys */
 static DEFINE_IDR(allocated_ptys);
-static DECLARE_MUTEX(allocated_ptys_lock);
+static DEFINE_MUTEX(allocated_ptys_lock);
 
 static struct vfsmount *devpts_mnt;
 static struct dentry *devpts_root;
@@ -186,10 +187,10 @@ retry:
 		return -ENOMEM;
 	}
 
-	down(&allocated_ptys_lock);
+	mutex_lock(&allocated_ptys_lock);
 	idr_ret = idr_get_new(&allocated_ptys, NULL, &index);
 	if (idr_ret < 0) {
-		up(&allocated_ptys_lock);
+		mutex_unlock(&allocated_ptys_lock);
 		if (idr_ret == -EAGAIN)
 			goto retry;
 		return -EIO;
@@ -197,18 +198,18 @@ retry:
 
 	if (index >= pty_limit) {
 		idr_remove(&allocated_ptys, index);
-		up(&allocated_ptys_lock);
+		mutex_unlock(&allocated_ptys_lock);
 		return -EIO;
 	}
-	up(&allocated_ptys_lock);
+	mutex_unlock(&allocated_ptys_lock);
 	return index;
 }
 
 void devpts_kill_index(int idx)
 {
-	down(&allocated_ptys_lock);
+	mutex_lock(&allocated_ptys_lock);
 	idr_remove(&allocated_ptys, idx);
-	up(&allocated_ptys_lock);
+	mutex_unlock(&allocated_ptys_lock);
 }
 
 int devpts_pty_new(struct tty_struct *tty)
_