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    Subject[PATCH 56/80] tty: Clean up the tty_init_dev changes further
    Date
    From: Alan Cox <alan@redhat.com>

    Fix up the naming, style and extract some bits of code into the driver
    specific code

    Signed-off-by: Alan Cox <alan@redhat.com>
    ---

    drivers/char/pty.c | 49 +++++++++++++++++++++++++++++++++-
    drivers/char/tty_io.c | 64 +++++++++++++++++---------------------------
    include/linux/tty_driver.h | 9 ++++++
    3 files changed, 81 insertions(+), 41 deletions(-)


    diff --git a/drivers/char/pty.c b/drivers/char/pty.c
    index 328e8ac..6e148ad 100644
    --- a/drivers/char/pty.c
    +++ b/drivers/char/pty.c
    @@ -391,6 +391,41 @@ static int pty_unix98_ioctl(struct tty_struct *tty, struct file *file,
    return -ENOIOCTLCMD;
    }

    +/**
    + * ptm_unix98_lookup - find a pty master
    + * @driver: ptm driver
    + * @idx: tty index
    + *
    + * Look up a pty master device. Called under the tty_mutex for now.
    + * This provides our locking.
    + */
    +
    +static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver, int idx)
    +{
    + struct tty_struct *tty = devpts_get_tty(idx);
    + if (tty)
    + tty = tty->link;
    + return tty;
    +}
    +
    +/**
    + * pts_unix98_lookup - find a pty slave
    + * @driver: pts driver
    + * @idx: tty index
    + *
    + * Look up a pty master device. Called under the tty_mutex for now.
    + * This provides our locking.
    + */
    +
    +static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver, int idx)
    +{
    + struct tty_struct *tty = devpts_get_tty(idx);
    + /* Master must be open before slave */
    + if (!tty)
    + return ERR_PTR(-EIO);
    + return tty;
    +}
    +
    static void pty_shutdown(struct tty_struct *tty)
    {
    /* We have our own method as we don't use the tty index */
    @@ -399,6 +434,7 @@ static void pty_shutdown(struct tty_struct *tty)
    }

    static const struct tty_operations ptm_unix98_ops = {
    + .lookup = ptm_unix98_lookup,
    .open = pty_open,
    .close = pty_close,
    .write = pty_write,
    @@ -411,6 +447,17 @@ static const struct tty_operations ptm_unix98_ops = {
    .shutdown = pty_shutdown
    };

    +static const struct tty_operations pty_unix98_ops = {
    + .lookup = pts_unix98_lookup,
    + .open = pty_open,
    + .close = pty_close,
    + .write = pty_write,
    + .write_room = pty_write_room,
    + .flush_buffer = pty_flush_buffer,
    + .chars_in_buffer = pty_chars_in_buffer,
    + .unthrottle = pty_unthrottle,
    + .set_termios = pty_set_termios,
    +};

    /**
    * ptmx_open - open a unix 98 pty master
    @@ -517,7 +564,7 @@ static void __init unix98_pty_init(void)
    pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
    TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
    pts_driver->other = ptm_driver;
    - tty_set_operations(pts_driver, &pty_ops);
    + tty_set_operations(pts_driver, &pty_unix98_ops);

    if (tty_register_driver(ptm_driver))
    panic("Couldn't register Unix98 ptm driver");
    diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
    index a540849..ac41af8 100644
    --- a/drivers/char/tty_io.c
    +++ b/drivers/char/tty_io.c
    @@ -1204,53 +1204,38 @@ static void tty_line_name(struct tty_driver *driver, int index, char *p)
    sprintf(p, "%s%d", driver->name, index + driver->name_base);
    }

    -/*
    - * find_tty() - find an existing tty, if any
    - * @driver: the driver for the tty
    - * @idx: the minor number
    +/**
    + * tty_driver_lookup_tty() - find an existing tty, if any
    + * @driver: the driver for the tty
    + * @idx: the minor number
    *
    - * Return the tty, if found or ERR_PTR() otherwise.
    + * Return the tty, if found or ERR_PTR() otherwise.
    *
    - * Locking: tty_mutex must be held. If tty is found, the mutex must
    - * be held until the 'fast-open' is also done.
    + * Locking: tty_mutex must be held. If tty is found, the mutex must
    + * be held until the 'fast-open' is also done. Will change once we
    + * have refcounting in the driver and per driver locking
    */
    -struct tty_struct *find_tty(struct tty_driver *driver, int idx)
    +struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver, int idx)
    {
    struct tty_struct *tty;

    - /* check whether we're reopening an existing tty */
    - if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
    - tty = devpts_get_tty(idx);
    - /*
    - * If we don't have a tty here on a slave open, it's because
    - * the master already started the close process and there's
    - * no relation between devpts file and tty anymore.
    - */
    - if (!tty && driver->subtype == PTY_TYPE_SLAVE)
    - return ERR_PTR(-EIO);
    + if (driver->ops->lookup)
    + return driver->ops->lookup(driver, idx);

    - /*
    - * tty is safe on because we are called with tty_mutex held
    - * and release_dev() won't change tty->count or tty->flags
    - * without grabbing tty_mutex.
    - */
    - if (tty && driver->subtype == PTY_TYPE_MASTER)
    - tty = tty->link;
    - } else
    tty = driver->ttys[idx];
    return tty;
    }

    -/*
    - * fast_tty_open() - fast re-open of an open tty
    - * @tty - the tty to open
    +/**
    + * tty_reopen() - fast re-open of an open tty
    + * @tty - the tty to open
    *
    - * Return 0 on success, -errno on error.
    + * Return 0 on success, -errno on error.
    *
    - * Locking: tty_mutex must be held from the time the tty was found
    - * till this open completes.
    + * Locking: tty_mutex must be held from the time the tty was found
    + * till this open completes.
    */
    -static int fast_tty_open(struct tty_struct *tty)
    +static int tty_reopen(struct tty_struct *tty)
    {
    struct tty_driver *driver = tty->driver;

    @@ -1271,9 +1256,7 @@ static int fast_tty_open(struct tty_struct *tty)
    tty->count++;
    tty->driver = driver; /* N.B. why do this every time?? */

    - /* FIXME */
    - if (!test_bit(TTY_LDISC, &tty->flags))
    - printk(KERN_ERR "fast_tty_open: no ldisc\n");
    + WARN_ON(!test_bit(TTY_LDISC, &tty->flags));

    return 0;
    }
    @@ -1312,14 +1295,14 @@ int tty_init_dev(struct tty_driver *driver, int idx,
    int retval = 0;

    /* check whether we're reopening an existing tty */
    - tty = find_tty(driver, idx);
    + tty = tty_driver_lookup_tty(driver, idx);
    if (IS_ERR(tty)) {
    retval = PTR_ERR(tty);
    goto end_init;
    }

    if (tty) {
    - retval = fast_tty_open(tty);
    + retval = tty_reopen(tty);
    if (retval)
    return retval;
    *ret_tty = tty;
    @@ -1440,6 +1423,8 @@ int tty_init_dev(struct tty_driver *driver, int idx,
    * All structures have been allocated, so now we install them.
    * Failures after this point use release_tty to clean up, so
    * there's no need to null out the local pointers.
    + *
    + * FIXME: We want a 'driver->install method ?
    */
    if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM))
    driver->ttys[idx] = tty;
    @@ -1466,9 +1451,8 @@ int tty_init_dev(struct tty_driver *driver, int idx,

    if (retval)
    goto release_mem_out;
    -success:
    - *ret_tty = tty;

    + *ret_tty = tty;
    /* All paths come through here to release the mutex */
    end_init:
    return retval;
    diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
    index 2322313..2c5c35c 100644
    --- a/include/linux/tty_driver.h
    +++ b/include/linux/tty_driver.h
    @@ -7,6 +7,14 @@
    * defined; unless noted otherwise, they are optional, and can be
    * filled in with a null pointer.
    *
    + * struct tty_struct * (*lookup)(struct tty_driver *self, int idx)
    + *
    + * Return the tty device corresponding to idx, NULL if there is not
    + * one currently in use and an ERR_PTR value on error. Called under
    + * tty_mutex (for now!)
    + *
    + * Optional method. Default behaviour is to use the ttys array
    + *
    * int (*open)(struct tty_struct * tty, struct file * filp);
    *
    * This routine is called when a particular tty device is opened.
    @@ -203,6 +211,7 @@ struct tty_struct;
    struct tty_driver;

    struct tty_operations {
    + struct tty_struct * (*lookup)(struct tty_driver *driver, int idx);
    int (*open)(struct tty_struct * tty, struct file * filp);
    void (*close)(struct tty_struct * tty, struct file * filp);
    void (*shutdown)(struct tty_struct *tty);


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