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tty: rename tty_kopen() and add new function tty_kopen_shared()

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Introduce a new function tty_kopen_shared() that yields a struct
tty_struct. The semantic difference to tty_kopen() is that the tty is
expected to be used already. So rename tty_kopen() to
tty_kopen_exclusive() for clearness, adapt the single user and put the
common code in a new static helper function.

tty_kopen_shared is to be used to implement an LED trigger for tty
devices in one of the next patches.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20201218104246.591315-2-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Uwe Kleine-König 2020-12-18 11:42:44 +01:00 committed by Greg Kroah-Hartman
parent 5c8fe583cc
commit 4ea3cd65e0
3 changed files with 42 additions and 21 deletions
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2
drivers/accessibility/speakup/spk_ttyio.c
View file

@ -152,7 +152,7 @@ static int spk_ttyio_initialise_ldisc(struct spk_synth *synth)
if (ret)
return ret;
tty = tty_kopen(dev);
tty = tty_kopen_exclusive(dev);
if (IS_ERR(tty))
return PTR_ERR(tty);

56
drivers/tty/tty_io.c
View file

@ -1875,22 +1875,7 @@ static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
return driver;
}
/**
* tty_kopen - open a tty device for kernel
* @device: dev_t of device to open
*
* Opens tty exclusively for kernel. Performs the driver lookup,
* makes sure it's not already opened and performs the first-time
* tty initialization.
*
* Returns the locked initialized &tty_struct
*
* Claims the global tty_mutex to serialize:
* - concurrent first-time tty initialization
* - concurrent tty driver removal w/ lookup
* - concurrent tty removal from driver table
*/
struct tty_struct *tty_kopen(dev_t device)
static struct tty_struct *tty_kopen(dev_t device, int shared)
{
struct tty_struct *tty;
struct tty_driver *driver;
@ -1905,7 +1890,7 @@ struct tty_struct *tty_kopen(dev_t device)
/* check whether we're reopening an existing tty */
tty = tty_driver_lookup_tty(driver, NULL, index);
if (IS_ERR(tty))
if (IS_ERR(tty) || shared)
goto out;
if (tty) {
@ -1923,7 +1908,42 @@ struct tty_struct *tty_kopen(dev_t device)
tty_driver_kref_put(driver);
return tty;
}
EXPORT_SYMBOL_GPL(tty_kopen);
/**
* tty_kopen_exclusive - open a tty device for kernel
* @device: dev_t of device to open
*
* Opens tty exclusively for kernel. Performs the driver lookup,
* makes sure it's not already opened and performs the first-time
* tty initialization.
*
* Returns the locked initialized &tty_struct
*
* Claims the global tty_mutex to serialize:
* - concurrent first-time tty initialization
* - concurrent tty driver removal w/ lookup
* - concurrent tty removal from driver table
*/
struct tty_struct *tty_kopen_exclusive(dev_t device)
{
return tty_kopen(device, 0);
}
EXPORT_SYMBOL_GPL(tty_kopen_exclusive);
/**
* tty_kopen_shared - open a tty device for shared in-kernel use
* @device: dev_t of device to open
*
* Opens an already existing tty for in-kernel use. Compared to
* tty_kopen_exclusive() above it doesn't ensure to be the only user.
*
* Locking is identical to tty_kopen() above.
*/
struct tty_struct *tty_kopen_shared(dev_t device)
{
return tty_kopen(device, 1);
}
EXPORT_SYMBOL_GPL(tty_kopen_shared);
/**
* tty_open_by_driver - open a tty device

5
include/linux/tty.h
View file

@ -416,7 +416,8 @@ extern struct tty_struct *get_current_tty(void);
/* tty_io.c */
extern int __init tty_init(void);
extern const char *tty_name(const struct tty_struct *tty);
extern struct tty_struct *tty_kopen(dev_t device);
extern struct tty_struct *tty_kopen_exclusive(dev_t device);
extern struct tty_struct *tty_kopen_shared(dev_t device);
extern void tty_kclose(struct tty_struct *tty);
extern int tty_dev_name_to_number(const char *name, dev_t *number);
extern int tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout);
@ -441,7 +442,7 @@ static inline int __init tty_init(void)
{ return 0; }
static inline const char *tty_name(const struct tty_struct *tty)
{ return "(none)"; }
static inline struct tty_struct *tty_kopen(dev_t device)
static inline struct tty_struct *tty_kopen_exclusive(dev_t device)
{ return ERR_PTR(-ENODEV); }
static inline void tty_kclose(struct tty_struct *tty)
{ }