tty: cleanup prohibition of direct opening for unix98 pty master

cleanup hack added in v2.6.27-3203-g15582d3

comment from that patch:

: pty: If the administrator creates a device for a ptmx slave we should not error
:
: The open path for ptmx slaves is via the ptmx device. Opening them any
: other way is not allowed. Vegard Nossum found that previously this was not
: the case and mknod foo c 128 42; cat foo would produce nasty diagnostics
:
: Signed-off-by: Alan Cox <alan@redhat.com>
: Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

devpts_get_tty() returns non-null only for inodes on devpts, but there is no
inodes for master-devices, /dev/ptmx (/dev/pts/ptmx) is the only way to open them.
Thus we can completely forbid lookup for master-devices and eliminate that hack in
tty_init_dev() because tty_open() will get EIO from tty_driver_lookup_tty().

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 1 insertions, 2 deletions

diff --git a/include/linux/tty.h b/include/linux/tty.h
index 5dbb3cb05a82..d3ebd765b548 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -480,8 +480,7 @@ extern void free_tty_struct(struct tty_struct *tty);
 extern void initialize_tty_struct(struct tty_struct *tty,
 		struct tty_driver *driver, int idx);
 extern void deinitialize_tty_struct(struct tty_struct *tty);
-extern struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
-								int first_ok);
+extern struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx);
 extern int tty_release(struct inode *inode, struct file *filp);
 extern int tty_init_termios(struct tty_struct *tty);