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

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>

diff --git a/drivers/accessibility/speakup/spk_ttyio.c b/drivers/accessibility/speakup/spk_ttyio.c
index 6284aff434a1af562c53781f2b2684a0b7bf9dbe..835d17455fcdb1a57e77f861c80a2033b6874122 100644 (file)
--- a/drivers/accessibility/speakup/spk_ttyio.c
+++ b/drivers/accessibility/speakup/spk_ttyio.c
@@ -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);
 

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 8034489337d75241b1a42d781839679446e83d82..62ccd021102da7ec69a09319052453f62ab30efa 100644 (file)
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -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 @@ out:
        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 c873f475f0a762da8205c7cb4be684d5a1cd5677..df707a5abface2377da7e96897b3549af2c6183d 100644 (file)
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -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)
 { }