[PATCH -next 17/27] tty: Simplify tty_release() state checks

Peter Hurley
2014-10-16T20:50:15Z

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.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
---
drivers/tty/tty_io.c | 19 +++++++++----------
1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 8fedd22..fb043b9 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1758,8 +1758,8 @@ 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];
long timeout = 0;
@@ -1774,10 +1774,9 @@ 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);
@@ -1821,7 +1820,7 @@ 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++;
@@ -1846,7 +1845,7 @@ int tty_release(struct inode *inode, struct file *filp)
timeout = MAX_SCHEDULE_TIMEOUT;
}

- 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));
@@ -1880,13 +1879,13 @@ 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
--
2.1.1