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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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