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    Subject[PATCH 20/41] TTY: add support for unnumbered device nodes
    Date
    This allows drivers like ttyprintk to avoid hacks to create an
    unnumbered node in /dev. It used to set TTY_DRIVER_DYNAMIC_DEV in
    flags and call device_create on its own. That is incorrect, because
    TTY_DRIVER_DYNAMIC_DEV may be set only if tty_register_device is
    called explicitly.

    Signed-off-by: Jiri Slaby <jslaby@suse.cz>
    ---
    drivers/char/ttyprintk.c | 17 ++++-------------
    drivers/tty/tty_io.c | 7 +++++--
    include/linux/tty_driver.h | 6 ++++++
    3 files changed, 15 insertions(+), 15 deletions(-)

    diff --git a/drivers/char/ttyprintk.c b/drivers/char/ttyprintk.c
    index be1c3fb..9e6272f 100644
    --- a/drivers/char/ttyprintk.c
    +++ b/drivers/char/ttyprintk.c
    @@ -178,13 +178,15 @@ static struct tty_driver *ttyprintk_driver;
    static int __init ttyprintk_init(void)
    {
    int ret = -ENOMEM;
    - void *rp;

    tty_port_init(&tpk_port.port);
    tpk_port.port.ops = &null_ops;
    mutex_init(&tpk_port.port_write_mutex);

    - ttyprintk_driver = alloc_tty_driver(1);
    + ttyprintk_driver = tty_alloc_driver(1,
    + TTY_DRIVER_RESET_TERMIOS |
    + TTY_DRIVER_REAL_RAW |
    + TTY_DRIVER_UNNUMBERED_NODE);
    if (!ttyprintk_driver)
    return ret;

    @@ -195,8 +197,6 @@ static int __init ttyprintk_init(void)
    ttyprintk_driver->type = TTY_DRIVER_TYPE_CONSOLE;
    ttyprintk_driver->init_termios = tty_std_termios;
    ttyprintk_driver->init_termios.c_oflag = OPOST | OCRNL | ONOCR | ONLRET;
    - ttyprintk_driver->flags = TTY_DRIVER_RESET_TERMIOS |
    - TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
    tty_set_operations(ttyprintk_driver, &ttyprintk_ops);

    ret = tty_register_driver(ttyprintk_driver);
    @@ -205,15 +205,6 @@ static int __init ttyprintk_init(void)
    goto error;
    }

    - /* create our unnumbered device */
    - rp = device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 3), NULL,
    - ttyprintk_driver->name);
    - if (IS_ERR(rp)) {
    - printk(KERN_ERR "Couldn't create ttyprintk device\n");
    - ret = PTR_ERR(rp);
    - goto error;
    - }
    -
    return 0;

    error:
    diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
    index 8181cb5..135e0e4 100644
    --- a/drivers/tty/tty_io.c
    +++ b/drivers/tty/tty_io.c
    @@ -1213,7 +1213,10 @@ static void pty_line_name(struct tty_driver *driver, int index, char *p)
    */
    static void tty_line_name(struct tty_driver *driver, int index, char *p)
    {
    - sprintf(p, "%s%d", driver->name, index + driver->name_base);
    + if (driver->flags & TTY_DRIVER_UNNUMBERED_NODE)
    + strcpy(p, driver->name);
    + else
    + sprintf(p, "%s%d", driver->name, index + driver->name_base);
    }

    /**
    @@ -3061,7 +3064,7 @@ struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
    struct tty_driver *driver;
    int err;

    - if (!lines)
    + if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
    return ERR_PTR(-EINVAL);

    driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
    diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
    index bea95ca..ca8eb54 100644
    --- a/include/linux/tty_driver.h
    +++ b/include/linux/tty_driver.h
    @@ -394,6 +394,11 @@ static inline struct tty_driver *tty_driver_kref_get(struct tty_driver *d)
    * TTY_DRIVER_EXCESSIVE_LINES -- do not allocate structures which are
    * needed per line for this driver as it would waste memory.
    * Applicable only to pty.
    + *
    + * TTY_DRIVER_UNNUMBERED_NODE -- do not create numbered /dev nodes. In
    + * other words create /dev/ttyprintk and not /dev/ttyprintk0.
    + * Applicable only when a driver for a single tty device is
    + * being allocated.
    */
    #define TTY_DRIVER_INSTALLED 0x0001
    #define TTY_DRIVER_RESET_TERMIOS 0x0002
    @@ -402,6 +407,7 @@ static inline struct tty_driver *tty_driver_kref_get(struct tty_driver *d)
    #define TTY_DRIVER_DEVPTS_MEM 0x0010
    #define TTY_DRIVER_HARDWARE_BREAK 0x0020
    #define TTY_DRIVER_EXCESSIVE_LINES 0x0040
    +#define TTY_DRIVER_UNNUMBERED_NODE 0x0080

    /* tty driver types */
    #define TTY_DRIVER_TYPE_SYSTEM 0x0001
    --
    1.7.10.4



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