[PATCH 56/80] tty: Clean up the tty_init_dev changes further

Alan Cox
2008-10-13T09:54:36Z

Fix up the naming, style and extract some bits of code into the driver
specific code

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

drivers/char/pty.c | 49 +++++++++++++++++++++++++++++++++-
drivers/char/tty_io.c | 64 +++++++++++++++++---------------------------
include/linux/tty_driver.h | 9 ++++++
3 files changed, 81 insertions(+), 41 deletions(-)

diff --git a/drivers/char/pty.c b/drivers/char/pty.c
index 328e8ac..6e148ad 100644
--- a/drivers/char/pty.c
+++ b/drivers/char/pty.c
@@ -391,6 +391,41 @@ static int pty_unix98_ioctl(struct tty_struct *tty, struct file *file,
return -ENOIOCTLCMD;
}

+/**
+ * ptm_unix98_lookup - find a pty master
+ * @driver: ptm driver
+ * @idx: tty index
+ *
+ * Look up a pty master device. Called under the tty_mutex for now.
+ * This provides our locking.
+ */
+
+static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver, int idx)
+{
+ struct tty_struct *tty = devpts_get_tty(idx);
+ if (tty)
+ tty = tty->link;
+ return tty;
+}
+
+/**
+ * pts_unix98_lookup - find a pty slave
+ * @driver: pts driver
+ * @idx: tty index
+ *
+ * Look up a pty master device. Called under the tty_mutex for now.
+ * This provides our locking.
+ */
+
+static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver, int idx)
+{
+ struct tty_struct *tty = devpts_get_tty(idx);
+ /* Master must be open before slave */
+ if (!tty)
+ return ERR_PTR(-EIO);
+ return tty;
+}
+
static void pty_shutdown(struct tty_struct *tty)
{
/* We have our own method as we don't use the tty index */
@@ -399,6 +434,7 @@ static void pty_shutdown(struct tty_struct *tty)
}

static const struct tty_operations ptm_unix98_ops = {
+ .lookup = ptm_unix98_lookup,
.open = pty_open,
.close = pty_close,
.write = pty_write,
@@ -411,6 +447,17 @@ static const struct tty_operations ptm_unix98_ops = {
.shutdown = pty_shutdown
};

+static const struct tty_operations pty_unix98_ops = {
+ .lookup = pts_unix98_lookup,
+ .open = pty_open,
+ .close = pty_close,
+ .write = pty_write,
+ .write_room = pty_write_room,
+ .flush_buffer = pty_flush_buffer,
+ .chars_in_buffer = pty_chars_in_buffer,
+ .unthrottle = pty_unthrottle,
+ .set_termios = pty_set_termios,
+};

/**
* ptmx_open - open a unix 98 pty master
@@ -517,7 +564,7 @@ static void __init unix98_pty_init(void)
pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
pts_driver->other = ptm_driver;
- tty_set_operations(pts_driver, &pty_ops);
+ tty_set_operations(pts_driver, &pty_unix98_ops);

if (tty_register_driver(ptm_driver))
panic("Couldn't register Unix98 ptm driver");
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index a540849..ac41af8 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -1204,53 +1204,38 @@ static void tty_line_name(struct tty_driver *driver, int index, char *p)
sprintf(p, "%s%d", driver->name, index + driver->name_base);
}

-/*
- * find_tty() - find an existing tty, if any
- * @driver: the driver for the tty
- * @idx: the minor number
+/**
+ * tty_driver_lookup_tty() - find an existing tty, if any
+ * @driver: the driver for the tty
+ * @idx: the minor number
*
- * Return the tty, if found or ERR_PTR() otherwise.
+ * Return the tty, if found or ERR_PTR() otherwise.
*
- * Locking: tty_mutex must be held. If tty is found, the mutex must
- * be held until the 'fast-open' is also done.
+ * Locking: tty_mutex must be held. If tty is found, the mutex must
+ * be held until the 'fast-open' is also done. Will change once we
+ * have refcounting in the driver and per driver locking
*/
-struct tty_struct *find_tty(struct tty_driver *driver, int idx)
+struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver, int idx)
{
struct tty_struct *tty;

- /* check whether we're reopening an existing tty */
- if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
- tty = devpts_get_tty(idx);
- /*
- * If we don't have a tty here on a slave open, it's because
- * the master already started the close process and there's
- * no relation between devpts file and tty anymore.
- */
- if (!tty && driver->subtype == PTY_TYPE_SLAVE)
- return ERR_PTR(-EIO);
+ if (driver->ops->lookup)
+ return driver->ops->lookup(driver, idx);

- /*
- * tty is safe on because we are called with tty_mutex held
- * and release_dev() won't change tty->count or tty->flags
- * without grabbing tty_mutex.
- */
- if (tty && driver->subtype == PTY_TYPE_MASTER)
- tty = tty->link;
- } else
tty = driver->ttys[idx];
return tty;
}

-/*
- * fast_tty_open() - fast re-open of an open tty
- * @tty - the tty to open
+/**
+ * tty_reopen() - fast re-open of an open tty
+ * @tty - the tty to open
*
- * Return 0 on success, -errno on error.
+ * Return 0 on success, -errno on error.
*
- * Locking: tty_mutex must be held from the time the tty was found
- * till this open completes.
+ * Locking: tty_mutex must be held from the time the tty was found
+ * till this open completes.
*/
-static int fast_tty_open(struct tty_struct *tty)
+static int tty_reopen(struct tty_struct *tty)
{
struct tty_driver *driver = tty->driver;

@@ -1271,9 +1256,7 @@ static int fast_tty_open(struct tty_struct *tty)
tty->count++;
tty->driver = driver; /* N.B. why do this every time?? */

- /* FIXME */
- if (!test_bit(TTY_LDISC, &tty->flags))
- printk(KERN_ERR "fast_tty_open: no ldisc\n");
+ WARN_ON(!test_bit(TTY_LDISC, &tty->flags));

return 0;
}
@@ -1312,14 +1295,14 @@ int tty_init_dev(struct tty_driver *driver, int idx,
int retval = 0;

/* check whether we're reopening an existing tty */
- tty = find_tty(driver, idx);
+ tty = tty_driver_lookup_tty(driver, idx);
if (IS_ERR(tty)) {
retval = PTR_ERR(tty);
goto end_init;
}

if (tty) {
- retval = fast_tty_open(tty);
+ retval = tty_reopen(tty);
if (retval)
return retval;
*ret_tty = tty;
@@ -1440,6 +1423,8 @@ 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;
@@ -1466,9 +1451,8 @@ int tty_init_dev(struct tty_driver *driver, int idx,

if (retval)
goto release_mem_out;
-success:
- *ret_tty = tty;

+ *ret_tty = tty;
/* All paths come through here to release the mutex */
end_init:
return retval;
diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
index 2322313..2c5c35c 100644
--- a/include/linux/tty_driver.h
+++ b/include/linux/tty_driver.h
@@ -7,6 +7,14 @@
* defined; unless noted otherwise, they are optional, and can be
* filled in with a null pointer.
*
+ * struct tty_struct * (*lookup)(struct tty_driver *self, int idx)
+ *
+ * Return the tty device corresponding to idx, NULL if there is not
+ * one currently in use and an ERR_PTR value on error. Called under
+ * tty_mutex (for now!)
+ *
+ * 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.
@@ -203,6 +211,7 @@ struct tty_struct;
struct tty_driver;

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