tty: Make vt's have a tty_port

The vt layer isn't safely handling reference counts to tty object on the input
side. Add a tty port structure to the vt layer in order to implement this using
the standard helpers.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/char/vt.c

@@ -783,6 +783,7 @@ int vc_allocate(unsigned int currcons)	/* return 0 on success */
 	    if (!vc)
 		return -ENOMEM;
 	    vc_cons[currcons].d = vc;
+	    tty_port_init(&vc->port);
 	    INIT_WORK(&vc_cons[currcons].SAK_work, vc_SAK);
 	    visual_init(vc, currcons, 1);
 	    if (!*vc->vc_uni_pagedir_loc)
@@ -2921,6 +2922,7 @@ static int __init con_init(void)
 	for (currcons = 0; currcons < MIN_NR_CONSOLES; currcons++) {
 		vc_cons[currcons].d = vc = kzalloc(sizeof(struct vc_data), GFP_NOWAIT);
 		INIT_WORK(&vc_cons[currcons].SAK_work, vc_SAK);
+		tty_port_init(&vc->port);
 		visual_init(vc, currcons, 1);
 		vc->vc_screenbuf = kzalloc(vc->vc_screenbuf_size, GFP_NOWAIT);
 		vc_init(vc, vc->vc_rows, vc->vc_cols,

include/linux/console_struct.h

@@ -21,6 +21,8 @@ struct vt_struct;
 #define NPAR 16
 
 struct vc_data {
+	struct tty_port port;			/* Upper level data */
+
 	unsigned short	vc_num;			/* Console number */
 	unsigned int	vc_cols;		/* [#] Console size */
 	unsigned int	vc_rows;