lkml.org 
[lkml]   [2019]   [Dec]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH v4 1/3] tty: rename tty_kopen() and add new function tty_kopen_shared()
    Date
    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>
    ---
    drivers/staging/speakup/spk_ttyio.c | 2 +-
    drivers/tty/tty_io.c | 58 ++++++++++++++++++++---------
    include/linux/tty.h | 5 ++-
    3 files changed, 44 insertions(+), 21 deletions(-)

    diff --git a/drivers/staging/speakup/spk_ttyio.c b/drivers/staging/speakup/spk_ttyio.c
    index 5a9eff08cb96..e9db06eae875 100644
    --- a/drivers/staging/speakup/spk_ttyio.c
    +++ b/drivers/staging/speakup/spk_ttyio.c
    @@ -147,7 +147,7 @@ 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 a1453fe10862..b718666ce73c 100644
    --- 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 +1908,44 @@ 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
    + * rnel. Performs the driver lookup,
    + * makes sure it's not already opened and performs the first-time
    + * tty initialization.
    + *
    + * 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 bfa4e2ee94a9..d0bcf3226fb2 100644
    --- a/include/linux/tty.h
    +++ b/include/linux/tty.h
    @@ -411,7 +411,8 @@ 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);
    @@ -436,7 +437,7 @@ 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)
    { }
    --
    2.24.0
    \
     
     \ /
      Last update: 2019-12-17 17:59    [W:5.716 / U:0.192 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site