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    Subject[PATCH -next v2 17/26] tty: Simplify tty_release() state checks
    Date
    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>
    ---
    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 c765260..bbc940d 100644
    --- a/drivers/tty/tty_io.c
    +++ b/drivers/tty/tty_io.c
    @@ -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];
    long timeout = 0;
    @@ -1775,10 +1775,9 @@ 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);
    @@ -1822,7 +1821,7 @@ 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++;
    @@ -1847,7 +1846,7 @@ 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));
    @@ -1881,13 +1880,13 @@ 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
    --
    2.1.3


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