TTY: add support for unnumbered device nodes

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>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/char/ttyprintk.c b/drivers/char/ttyprintk.c
index be1c3fb186c1bad4754394df80dae9e2a7258f08..9e6272f0b98c0052361658cb6764b635cf72800a 100644 (file)
--- 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 a67609b9f21b9fb96e05bbaccb788d71ab3848c2..4d9898c2b641d8981c505d150f19db89b5313de9 100644 (file)
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1216,7 +1216,10 @@ 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);
 }
 
 /**
@@ -3076,7 +3079,7 @@ 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 1a85f003d646086115235fdfc0d15e6fc919f097..44e05b75d57347d42b1c6fafd2e1f0c1783acfcd 100644 (file)
--- 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_DYNAMIC_ALLOC -- do not allocate structures which are
  *     needed per line for this driver as it would waste memory.
  *     The driver will take care.
+ *
+ * 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_DYNAMIC_ALLOC       0x0040
+#define TTY_DRIVER_UNNUMBERED_NODE     0x0080
 
 /* tty driver types */
 #define TTY_DRIVER_TYPE_SYSTEM         0x0001