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    Subject[PATCH 16/24] PTY: add tty_port
    Date
    This has *no* function in the PTY driver yet. However as the tty
    buffers will move to the tty_port structure, we will need tty_port for
    all TTYs in the system, PTY inclusive.

    For PTYs this is ensured by allocating 2 tty_port's in pty_install,
    i.e. where the tty->link is allocated. Both tty_port's are properly
    assigned to each end of the tty.

    Freeing is done at the same place where tty is freed, i.e. in
    tty->ops->cleanup.

    This means BTW that tty_port does not outlive TTY in PTY. This might
    be a subject to change in the future if we see some problems.

    Signed-off-by: Jiri Slaby <jslaby@suse.cz>
    ---
    drivers/tty/pty.c | 25 +++++++++++++++++++++----
    1 file changed, 21 insertions(+), 4 deletions(-)

    diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
    index 881888f..b50fc1c 100644
    --- a/drivers/tty/pty.c
    +++ b/drivers/tty/pty.c
    @@ -286,12 +286,15 @@ static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
    bool legacy)
    {
    struct tty_struct *o_tty;
    + struct tty_port *ports[2];
    int idx = tty->index;
    int retval = -ENOMEM;

    o_tty = alloc_tty_struct();
    - if (!o_tty)
    - goto err;
    + ports[0] = kmalloc(sizeof **ports, GFP_KERNEL);
    + ports[1] = kmalloc(sizeof **ports, GFP_KERNEL);
    + if (!o_tty || !ports[0] || !ports[1])
    + goto err_free_tty;
    if (!try_module_get(driver->other->owner)) {
    /* This cannot in fact currently happen */
    goto err_free_tty;
    @@ -335,6 +338,10 @@ static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
    /* Establish the links in both directions */
    tty->link = o_tty;
    o_tty->link = tty;
    + tty_port_init(ports[0]);
    + tty_port_init(ports[1]);
    + o_tty->port = ports[0];
    + tty->port = ports[1];

    tty_driver_kref_get(driver);
    tty->count++;
    @@ -348,11 +355,17 @@ err_deinit_tty:
    deinitialize_tty_struct(o_tty);
    module_put(o_tty->driver->owner);
    err_free_tty:
    + kfree(ports[0]);
    + kfree(ports[1]);
    free_tty_struct(o_tty);
    -err:
    return retval;
    }

    +static void pty_cleanup(struct tty_struct *tty)
    +{
    + kfree(tty->port);
    +}
    +
    /* Traditional BSD devices */
    #ifdef CONFIG_LEGACY_PTYS

    @@ -391,6 +404,7 @@ static const struct tty_operations master_pty_ops_bsd = {
    .unthrottle = pty_unthrottle,
    .set_termios = pty_set_termios,
    .ioctl = pty_bsd_ioctl,
    + .cleanup = pty_cleanup,
    .resize = pty_resize
    };

    @@ -404,6 +418,7 @@ static const struct tty_operations slave_pty_ops_bsd = {
    .chars_in_buffer = pty_chars_in_buffer,
    .unthrottle = pty_unthrottle,
    .set_termios = pty_set_termios,
    + .cleanup = pty_cleanup,
    .resize = pty_resize
    };

    @@ -555,6 +570,7 @@ static const struct tty_operations ptm_unix98_ops = {
    .set_termios = pty_set_termios,
    .ioctl = pty_unix98_ioctl,
    .shutdown = pty_unix98_shutdown,
    + .cleanup = pty_cleanup,
    .resize = pty_resize
    };

    @@ -570,7 +586,8 @@ static const struct tty_operations pty_unix98_ops = {
    .chars_in_buffer = pty_chars_in_buffer,
    .unthrottle = pty_unthrottle,
    .set_termios = pty_set_termios,
    - .shutdown = pty_unix98_shutdown
    + .shutdown = pty_unix98_shutdown,
    + .cleanup = pty_cleanup,
    };

    /**
    --
    1.7.10.3



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