[Devel] [PATCH RHEL7 COMMIT] Revert "pty: split Unix98 init routines"

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-229.7.2-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-229.7.2.vz7.6.3
------>
commit ee5a5380520330fedde1a323d5ca3cb5cad20b4f
Author: Vladimir Davydov <vdavydov at parallels.com>
Date:   Fri Aug 28 18:32:03 2015 +0400

    Revert "pty: split Unix98 init routines"
    
    Patchset description:
    
    Zap Unix98 pty virtualization
    
    Unix98 ptys are already
    virtualized on the VFS layer, nothing needs to be done on the driver's
    side. We don't even have this in PCS6.
    
    The patch set makes ptmx device system-wide while its class, tty_class, is
    still virtualized. Since it's now system-wide, we have to add its sysfs entry
    to ve.default_sysfs_permissions, but since its class is virtualized, we won't
    be able to do it (see sysfs_perms_set -> sysfs_find_dirent).
    
    As a result, if the container relies on sysfs while creating devnodes,
    it will not find ptmx and therefore fallback to legacy ptys, which we
    are going to drop.
    The last patch (ve/pty: create ptmx device per ve namespace) addresses this.
    
    ===
    This patch description:
    
    This reverts commit 3aec66abd43440bc7dd4c6bbe84734adb6d82851.
    
    Signed-off-by: Vladimir Davydov <vdavydov at parallels.com>
---
 drivers/tty/pty.c | 100 ++++++++----------------------------------------------
 1 file changed, 15 insertions(+), 85 deletions(-)

diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index 56c0a21..bd17a45 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -820,62 +820,25 @@ err_file:
 
 static struct file_operations ptmx_fops;
 
-static void __unix98_unregister_ptmx(void)
-{
-	unregister_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1);
-	cdev_del(&ptmx_cdev);
-}
-
-static int __unix98_register_ptmx(void)
- {
-	int err;
-
-	cdev_init(&ptmx_cdev, &ptmx_fops);
-	err = cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1);
-	if (err) {
-		printk(KERN_ERR "Couldn't add /dev/ptmx device");
-		return err;
-	}
-	err = register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx");
-	if (err < 0) {
-		printk(KERN_ERR "Couldn't register /dev/ptmx driver");
-		goto err_ptmx_register;
-	}
-	return 0;
-
-err_ptmx_register:
-	cdev_del(&ptmx_cdev);
-	return err;
-}
-
-static int __unix98_pty_init(struct tty_driver **ptm_driver_p,
-					struct tty_driver **pts_driver_p)
+static void __init unix98_pty_init(void)
 {
-	struct tty_driver *ptm_driver, *pts_driver;
-	int err;
-	struct device *dev;
-
 	ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
 			TTY_DRIVER_RESET_TERMIOS |
 			TTY_DRIVER_REAL_RAW |
 			TTY_DRIVER_DYNAMIC_DEV |
 			TTY_DRIVER_DEVPTS_MEM |
 			TTY_DRIVER_DYNAMIC_ALLOC);
-	if (IS_ERR(ptm_driver)) {
-		printk(KERN_ERR "Couldn't allocate Unix98 ptm driver");
-		return PTR_ERR(ptm_driver);
-	}
+	if (IS_ERR(ptm_driver))
+		panic("Couldn't allocate Unix98 ptm driver");
 	pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
 			TTY_DRIVER_RESET_TERMIOS |
 			TTY_DRIVER_REAL_RAW |
 			TTY_DRIVER_DYNAMIC_DEV |
 			TTY_DRIVER_DEVPTS_MEM |
 			TTY_DRIVER_DYNAMIC_ALLOC);
-	if (IS_ERR(pts_driver)) {
-		printk(KERN_ERR "Couldn't allocate Unix98 pts driver");
-		err = PTR_ERR(pts_driver);
-		goto err_pts_alloc;
-	}
+	if (IS_ERR(pts_driver))
+		panic("Couldn't allocate Unix98 pts driver");
+
 	ptm_driver->driver_name = "pty_master";
 	ptm_driver->name = "ptm";
 	ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
@@ -905,53 +868,20 @@ static int __unix98_pty_init(struct tty_driver **ptm_driver_p,
 	pts_driver->other = ptm_driver;
 	tty_set_operations(pts_driver, &pty_unix98_ops);
 
-	err = tty_register_driver(ptm_driver);
-	if (err) {
-		printk(KERN_ERR "Couldn't register Unix98 ptm driver");
-		goto err_ptm_register;
-	}
-	err = tty_register_driver(pts_driver);
-	if (err) {
-		printk(KERN_ERR "Couldn't register Unix98 pts driver");
-		goto err_pts_register;
-	}
+	if (tty_register_driver(ptm_driver))
+		panic("Couldn't register Unix98 ptm driver");
+	if (tty_register_driver(pts_driver))
+		panic("Couldn't register Unix98 pts driver");
 
 	/* Now create the /dev/ptmx special device */
 	tty_default_fops(&ptmx_fops);
 	ptmx_fops.open = ptmx_open;
 
-	err = __unix98_register_ptmx();
-	if (err)
-		goto err_ptmx_register;
-
-	dev = device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
-	if (IS_ERR(dev)) {
-		err = PTR_ERR(dev);
-		goto err_ptmx_create;
-	}
-
-	*ptm_driver_p = ptm_driver;
-	*pts_driver_p = pts_driver;
-
-	return 0;
-
-err_ptmx_create:
-	__unix98_unregister_ptmx();
-err_ptmx_register:
-	tty_unregister_driver(pts_driver);
-err_pts_register:
-	tty_unregister_driver(ptm_driver);
-err_ptm_register:
-	put_tty_driver(pts_driver);
-err_pts_alloc:
-	put_tty_driver(ptm_driver);
-	return err;
-}
-
-static void __init unix98_pty_init(void)
-{
-       if (__unix98_pty_init(&ptm_driver, &pts_driver))
-               panic("Failed to init legacy ptys");
+	cdev_init(&ptmx_cdev, &ptmx_fops);
+	if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
+	    register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
+		panic("Couldn't register /dev/ptmx driver");
+	device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
 }
 
 #else