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@xxxxxxxxxxxxxx>
---
drivers/accessibility/speakup/spk_ttyio.c | 2 +-
drivers/tty/tty_io.c | 56 +++++++++++++++--------
include/linux/tty.h | 5 +-
3 files changed, 42 insertions(+), 21 deletions(-)
diff --git a/drivers/accessibility/speakup/spk_ttyio.c b/drivers/accessibility/speakup/spk_ttyio.c
index a831ff64f8ba..991b21017a01 100644
--- a/drivers/accessibility/speakup/spk_ttyio.c
+++ b/drivers/accessibility/speakup/spk_ttyio.c
@@ -149,7 +149,7 @@ 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);
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index ceed72c9a88f..8aede3d2c1e0 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1871,22 +1871,7 @@ 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;
@@ -1901,7 +1886,7 @@ 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) {
@@ -1919,7 +1904,42 @@ 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
diff --git a/include/linux/tty.h b/include/linux/tty.h
index a99e9b8e4e31..c867d6fe67c4 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -413,7 +413,8 @@ 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);
@@ -438,7 +439,7 @@ 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)
{ }
--
2.28.0
