[PATCH 52/76] tty: More driver operations

Alan Cox
2008-10-05T16:23:52Z

We have the lookup operation abstracted which is nice for pty cleanup but
we really want to abstract the add/remove entries as well so that we can
pull the pty code out of the tty core and create a clear defined interface
for the tty driver table.

Signed-off-by: Alan Cox <alan@redhat.com>
---

drivers/char/pty.c | 16 ++++++++++++
drivers/char/tty_io.c | 57 ++++++++++++++++++++++++++++++++++++--------
include/linux/tty_driver.h | 16 ++++++++++++
3 files changed, 79 insertions(+), 10 deletions(-)

diff --git a/drivers/char/pty.c b/drivers/char/pty.c
index 0fdfa05..4e6490b 100644
--- a/drivers/char/pty.c
+++ b/drivers/char/pty.c
@@ -433,8 +433,22 @@ static void pty_shutdown(struct tty_struct *tty)
kfree(tty->termios_locked);
}

+/* We have no need to install and remove our tty objects as devpts does all
+ the work for us */
+
+static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
+{
+ return 0;
+}
+
+static void pty_remove(struct tty_driver *driver, struct tty_struct *tty)
+{
+}
+
static const struct tty_operations ptm_unix98_ops = {
.lookup = ptm_unix98_lookup,
+ .install = pty_install,
+ .remove = pty_remove,
.open = pty_open,
.close = pty_close,
.write = pty_write,
@@ -449,6 +463,8 @@ static const struct tty_operations ptm_unix98_ops = {

static const struct tty_operations pty_unix98_ops = {
.lookup = pts_unix98_lookup,
+ .install = pty_install,
+ .remove = pty_remove,
.open = pty_open,
.close = pty_close,
.write = pty_write,
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 47aa437..888380f 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -1189,7 +1189,7 @@ static void pty_line_name(struct tty_driver *driver, int index, char *p)
}

/**
- * pty_line_name - generate name for a tty
+ * tty_line_name - generate name for a tty
* @driver: the tty driver in use
* @index: the minor number
* @p: output buffer of at least 7 bytes
@@ -1222,13 +1222,51 @@ struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver, int idx)
if (driver->ops->lookup)
return driver->ops->lookup(driver, idx);

- tty = driver->ttys[idx];
+ tty = driver->ttys[idx];
return tty;
}

/**
- * tty_reopen() - fast re-open of an open tty
- * @tty - the tty to open
+ * tty_driver_install_tty() - install a tty entry in the driver
+ * @driver: the driver for the tty
+ * @tty: the tty
+ *
+ * Install a tty object into the driver tables. The tty->index field
+ * will be set by the time this is called.
+ *
+ * Locking: tty_mutex for now
+ */
+static int tty_driver_install_tty(struct tty_driver *driver,
+ struct tty_struct *tty)
+{
+ if (driver->ops->install)
+ return driver->ops->install(driver, tty);
+ driver->ttys[tty->index] = tty;
+ return 0;
+}
+
+/**
+ * tty_driver_remove_tty() - remove a tty from the driver tables
+ * @driver: the driver for the tty
+ * @idx: the minor number
+ *
+ * Remvoe a tty object from the driver tables. The tty->index field
+ * will be set by the time this is called.
+ *
+ * Locking: tty_mutex for now
+ */
+static void tty_driver_remove_tty(struct tty_driver *driver,
+ struct tty_struct *tty)
+{
+ if (driver->ops->remove)
+ driver->ops->remove(driver, tty);
+ else
+ driver->ttys[tty->index] = NULL;
+}
+
+/*
+ * tty_reopen() - fast re-open of an open tty
+ * @tty - the tty to open
*
* Return 0 on success, -errno on error.
*
@@ -1423,11 +1461,7 @@ int tty_init_dev(struct tty_driver *driver, int idx,
* All structures have been allocated, so now we install them.
* Failures after this point use release_tty to clean up, so
* there's no need to null out the local pointers.
- *
- * FIXME: We want a 'driver->install method ?
*/
- if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM))
- driver->ttys[idx] = tty;

if (!*tp_loc)
*tp_loc = tp;
@@ -1441,6 +1475,9 @@ int tty_init_dev(struct tty_driver *driver, int idx,
tty_driver_kref_get(driver);
tty->count++;

+ if (tty_driver_install_tty(driver, tty) < 0)
+ goto release_mem_out;
+
/*
* Structures all installed ... call the ldisc open routines.
* If we fail here just call release_tty to clean up. No need
@@ -1502,7 +1539,7 @@ EXPORT_SYMBOL(tty_free_termios);

void tty_shutdown(struct tty_struct *tty)
{
- tty->driver->ttys[tty->index] = NULL;
+ tty_driver_remove_tty(tty->driver, tty);
tty_free_termios(tty);
}
EXPORT_SYMBOL(tty_shutdown);
@@ -1615,7 +1652,7 @@ void tty_release_dev(struct file *filp)
"free (%s)\n", tty->name);
return;
}
- if (!(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
+ if (!devpts) {
if (tty != tty->driver->ttys[idx]) {
printk(KERN_DEBUG "tty_release_dev: driver.table[%d] not tty "
"for (%s)\n", idx, tty->name);
diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
index ba891dd..005d06a 100644
--- a/include/linux/tty_driver.h
+++ b/include/linux/tty_driver.h
@@ -15,6 +15,20 @@
*
* Optional method. Default behaviour is to use the ttys array
*
+ * int (*install)(struct tty_driver *self, struct tty_struct *tty)
+ *
+ * Install a new tty into the tty driver internal tables. Used in
+ * conjunction with lookup and remove methods.
+ *
+ * Optional method. Default behaviour is to use the ttys array
+ *
+ * void (*remove)(struct tty_driver *self, struct tty_struct *tty)
+ *
+ * Remove a closed tty from the tty driver internal tables. Used in
+ * conjunction with lookup and remove methods.
+ *
+ * Optional method. Default behaviour is to use the ttys array
+ *
* int (*open)(struct tty_struct * tty, struct file * filp);
*
* This routine is called when a particular tty device is opened.
@@ -212,6 +226,8 @@ struct tty_driver;

struct tty_operations {
struct tty_struct * (*lookup)(struct tty_driver *driver, int idx);
+ int (*install)(struct tty_driver *driver, struct tty_struct *tty);
+ void (*remove)(struct tty_driver *driver, struct tty_struct *tty);
int (*open)(struct tty_struct * tty, struct file * filp);
void (*close)(struct tty_struct * tty, struct file * filp);
void (*shutdown)(struct tty_struct *tty);