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tty: Simplify tty_release() state checks 

The local o_tty variable in tty_release() is now accessed only
when closing the pty master.

Set o_tty to slave pty when closing pty master, otherwise NULL;
use o_tty != NULL as replacement for pty_master.

Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Hurley 2014-11-05 12:13:00 -05:00 committed by Greg Kroah-Hartman
parent 359b9fb5c4
commit 7ffb6da93c
1 changed files with 9 additions and 10 deletions
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19
drivers/tty/tty_io.c
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@ -1759,8 +1759,8 @@ static int tty_release_checks(struct tty_struct *tty, int idx)
int tty_release(struct inode *inode, struct file *filp)
{
struct tty_struct *tty = file_tty(filp);
struct tty_struct *o_tty;
int pty_master, do_sleep, final;
struct tty_struct *o_tty = NULL;
int do_sleep, final;
int idx;
char buf[64];
@ -1773,10 +1773,9 @@ int tty_release(struct inode *inode, struct file *filp)
__tty_fasync(-1, filp, 0);
idx = tty->index;
pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER);
/* Review: parallel close */
o_tty = tty->link;
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER)
o_tty = tty->link;
if (tty_release_checks(tty, idx)) {
tty_unlock(tty);
@ -1820,7 +1819,7 @@ int tty_release(struct inode *inode, struct file *filp)
do_sleep++;
}
}
if (pty_master && o_tty->count <= 1) {
if (o_tty && o_tty->count <= 1) {
if (waitqueue_active(&o_tty->read_wait)) {
wake_up_poll(&o_tty->read_wait, POLLIN);
do_sleep++;
@ -1838,7 +1837,7 @@ int tty_release(struct inode *inode, struct file *filp)
schedule();
}
if (pty_master) {
if (o_tty) {
if (--o_tty->count < 0) {
printk(KERN_WARNING "%s: bad pty slave count (%d) for %s\n",
__func__, o_tty->count, tty_name(o_tty, buf));
@ -1872,13 +1871,13 @@ int tty_release(struct inode *inode, struct file *filp)
if (!tty->count) {
read_lock(&tasklist_lock);
session_clear_tty(tty->session);
if (pty_master)
if (o_tty)
session_clear_tty(o_tty->session);
read_unlock(&tasklist_lock);
}
/* check whether both sides are closing ... */
final = !tty->count && !(pty_master && o_tty->count);
final = !tty->count && !(o_tty && o_tty->count);
tty_unlock_pair(tty, o_tty);
/* At this point, the tty->count == 0 should ensure a dead tty