[PATCH 63/80] Simplify devpts_get_tty()

Alan Cox
2008-10-13T09:58:22Z

From: Sukadev Bhattiprolu <sukadev@us.ibm.com>

As pointed out by H. Peter Anvin, since the inode for the pty is known,
we don't need to look it up.

Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: Alan Cox <alan@redhat.com>
---

fs/devpts/inode.c | 17 +++++------------
1 files changed, 5 insertions(+), 12 deletions(-)

diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index 638db9b..b292ed7 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -27,6 +27,7 @@
#define DEVPTS_SUPER_MAGIC 0x1cd1

#define DEVPTS_DEFAULT_MODE 0600
+#define PTMX_MINOR 2

extern int pty_limit; /* Config limit on Unix98 ptys */
static DEFINE_IDA(allocated_ptys);
@@ -247,19 +248,11 @@ int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty)

struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number)
{
- struct dentry *dentry = get_node(number);
- struct tty_struct *tty;
-
- tty = NULL;
- if (!IS_ERR(dentry)) {
- if (dentry->d_inode)
- tty = dentry->d_inode->i_private;
- dput(dentry);
- }
-
- mutex_unlock(&devpts_root->d_inode->i_mutex);
+ BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));

- return tty;
+ if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
+ return (struct tty_struct *)pts_inode->i_private;
+ return NULL;
}

void devpts_pty_kill(struct tty_struct *tty)