Simplify devpts_pty_kill

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From: Linux Kernel Mailing List
Date: Monday, October 13, 2008 - 11:03 am

Gitweb:     http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=a6f37d...
Commit:     a6f37daa8b892fd29dd71be0de61460a478cb122
Parent:     89a52e109e2e2fe8bbd4e316cdb910774519c029
Author:     Sukadev Bhattiprolu <sukadev@us.ibm.com>
AuthorDate: Mon Oct 13 10:43:27 2008 +0100
Committer:  Linus Torvalds <torvalds@linux-foundation.org>
CommitDate: Mon Oct 13 09:51:43 2008 -0700

    Simplify devpts_pty_kill
    
    When creating a new pty, save the pty's inode in the tty->driver_data.
    Use this inode in pty_kill() to identify the devpts instance. Since
    we now have the inode for the pty, we can skip get_node() lookup and
    remove the unused get_node().
    
    TODO:
    	- check if the mutex_lock is needed in pty_kill().
    
    Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
    Signed-off-by: Alan Cox <alan@redhat.com>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 fs/devpts/inode.c |   29 ++++++++++++-----------------
 1 files changed, 12 insertions(+), 17 deletions(-)

diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index 50e885f..a70d5d0 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -170,14 +170,6 @@ static struct file_system_type devpts_fs_type = {
  * to the System V naming convention
  */
 
-static struct dentry *get_node(int num)
-{
-	char s[12];
-	struct dentry *root = devpts_root;
-	mutex_lock(&root->d_inode->i_mutex);
-	return lookup_one_len(s, root, sprintf(s, "%d", num));
-}
-
 int devpts_new_index(struct inode *ptmx_inode)
 {
 	int index;
@@ -235,6 +227,7 @@ int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty)
 	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 	init_special_inode(inode, S_IFCHR|config.mode, device);
 	inode->i_private = tty;
+	tty->driver_data = inode;
 
 	sprintf(s, "%d", number);
 
@@ -262,18 +255,20 @@ struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number)
 
 void devpts_pty_kill(struct tty_struct *tty)
 {
-	int number = tty->index;
-	struct dentry *dentry = get_node(number);
+	struct inode *inode = tty->driver_data;
+	struct dentry *dentry;
 
-	if (!IS_ERR(dentry)) {
-		struct inode *inode = dentry->d_inode;
-		if (inode) {
-			inode->i_nlink--;
-			d_delete(dentry);
-			dput(dentry);
-		}
+	BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
+
+	mutex_lock(&devpts_root->d_inode->i_mutex);
+
+	dentry = d_find_alias(inode);
+	if (dentry && !IS_ERR(dentry)) {
+		inode->i_nlink--;
+		d_delete(dentry);
 		dput(dentry);
 	}
+
 	mutex_unlock(&devpts_root->d_inode->i_mutex);
 }
 
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Simplify devpts_pty_kill, Linux Kernel Mailing ..., (Mon Oct 13, 11:03 am)