[PATCH 54/76] tty: extract the pty init time special cases

Alan Cox
2008-10-05T16:24:38Z

The majority of the remaining init_dev code is pty special cases. We
refactor this code into the driver->install method.

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

drivers/char/pty.c | 126 ++++++++++++++++++++++++++++---
drivers/char/tty_io.c | 198 +++++++++++++++++--------------------------------
include/linux/tty.h | 5 +
3 files changed, 187 insertions(+), 142 deletions(-)

diff --git a/drivers/char/pty.c b/drivers/char/pty.c
index c984500..c5a192d 100644
--- a/drivers/char/pty.c
+++ b/drivers/char/pty.c
@@ -227,7 +227,58 @@ static void pty_set_termios(struct tty_struct *tty, struct ktermios *old_termios
tty->termios->c_cflag |= (CS8 | CREAD);
}

+static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
+{
+ struct tty_struct *o_tty;
+ int idx = tty->index;
+ int retval;
+
+ o_tty = alloc_tty_struct();
+ if (!o_tty)
+ return -ENOMEM;
+ if (!try_module_get(driver->other->owner)) {
+ /* This cannot in fact currently happen */
+ free_tty_struct(o_tty);
+ return -ENOMEM;
+ }
+ initialize_tty_struct(o_tty, driver->other, idx);
+
+ /* We always use new tty termios data so we can do this
+ the easy way .. */
+ retval = tty_init_termios(tty);
+ if (retval)
+ goto free_mem_out;
+
+ retval = tty_init_termios(o_tty);
+ if (retval) {
+ tty_free_termios(tty);
+ goto free_mem_out;
+ }
+
+ /*
+ * Everything allocated ... set up the o_tty structure.
+ */
+ driver->other->ttys[idx] = o_tty;
+ tty_driver_kref_get(driver->other);
+ if (driver->subtype == PTY_TYPE_MASTER)
+ o_tty->count++;
+ /* Establish the links in both directions */
+ tty->link = o_tty;
+ o_tty->link = tty;
+
+ tty_driver_kref_get(driver);
+ tty->count++;
+ driver->ttys[idx] = tty;
+ return 0;
+free_mem_out:
+ module_put(o_tty->driver->owner);
+ free_tty_struct(o_tty);
+ return -ENOMEM;
+}
+
+
static const struct tty_operations pty_ops = {
+ .install = pty_install,
.open = pty_open,
.close = pty_close,
.write = pty_write,
@@ -332,6 +383,7 @@ static inline void legacy_pty_init(void) { }
int pty_limit = NR_UNIX98_PTY_DEFAULT;
static int pty_limit_min = 0;
static int pty_limit_max = NR_UNIX98_PTY_MAX;
+static int pty_count = 0;

static struct cdev ptmx_cdev;

@@ -351,6 +403,7 @@ static struct ctl_table pty_table[] = {
.procname = "nr",
.maxlen = sizeof(int),
.mode = 0444,
+ .data = &pty_count,
.proc_handler = &proc_dointvec,
}, {
.ctl_name = 0
@@ -426,7 +479,7 @@ static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver, int idx)
return tty;
}

-static void pty_shutdown(struct tty_struct *tty)
+static void pty_unix98_shutdown(struct tty_struct *tty)
{
/* We have our own method as we don't use the tty index */
kfree(tty->termios);
@@ -436,19 +489,71 @@ static void pty_shutdown(struct tty_struct *tty)
/* 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)
+static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
{
+ struct tty_struct *o_tty;
+ int idx = tty->index;
+
+ o_tty = alloc_tty_struct();
+ if (!o_tty)
+ return -ENOMEM;
+ if (!try_module_get(driver->other->owner)) {
+ /* This cannot in fact currently happen */
+ free_tty_struct(o_tty);
+ return -ENOMEM;
+ }
+ initialize_tty_struct(o_tty, driver->other, idx);
+
+ tty->termios = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
+ if (tty->termios == NULL)
+ goto free_mem_out;
+ *tty->termios = driver->init_termios;
+ tty->termios_locked = kzalloc(sizeof(struct ktermios), GFP_KERNEL);
+ if (tty->termios_locked == NULL)
+ goto free_mem_out;
+ o_tty->termios = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
+ if (o_tty->termios == NULL)
+ goto free_mem_out;
+ *o_tty->termios = driver->other->init_termios;
+ o_tty->termios_locked = kzalloc(sizeof(struct ktermios), GFP_KERNEL);
+ if (o_tty->termios_locked == NULL)
+ goto free_mem_out;
+
+ tty_driver_kref_get(driver->other);
+ if (driver->subtype == PTY_TYPE_MASTER)
+ o_tty->count++;
+ /* Establish the links in both directions */
+ tty->link = o_tty;
+ o_tty->link = tty;
+ /*
+ * 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.
+ */
+ tty_driver_kref_get(driver);
+ tty->count++;
+ pty_count++;
return 0;
+free_mem_out:
+ kfree(o_tty->termios);
+ module_put(o_tty->driver->owner);
+ free_tty_struct(o_tty);
+ kfree(tty->termios_locked);
+ kfree(tty->termios);
+ free_tty_struct(tty);
+ module_put(driver->owner);
+ return -ENOMEM;
}

-static void pty_remove(struct tty_driver *driver, struct tty_struct *tty)
+static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
{
+ pty_count--;
}

static const struct tty_operations ptm_unix98_ops = {
.lookup = ptm_unix98_lookup,
- .install = pty_install,
- .remove = pty_remove,
+ .install = pty_unix98_install,
+ .remove = pty_unix98_remove,
.open = pty_open,
.close = pty_close,
.write = pty_write,
@@ -458,13 +563,13 @@ static const struct tty_operations ptm_unix98_ops = {
.unthrottle = pty_unthrottle,
.set_termios = pty_set_termios,
.ioctl = pty_unix98_ioctl,
- .shutdown = pty_shutdown
+ .shutdown = pty_unix98_shutdown
};

static const struct tty_operations pty_unix98_ops = {
.lookup = pts_unix98_lookup,
- .install = pty_install,
- .remove = pty_remove,
+ .install = pty_unix98_install,
+ .remove = pty_unix98_remove,
.open = pty_open,
.close = pty_close,
.write = pty_write,
@@ -473,6 +578,7 @@ static const struct tty_operations pty_unix98_ops = {
.chars_in_buffer = pty_chars_in_buffer,
.unthrottle = pty_unthrottle,
.set_termios = pty_set_termios,
+ .shutdown = pty_unix98_shutdown
};

/**
@@ -589,10 +695,6 @@ static void __init unix98_pty_init(void)
if (tty_register_driver(pts_driver))
panic("Couldn't register Unix98 pts driver");

- /* FIXME: WTF */
-#if 0
- pty_table[1].data = &ptm_driver->refcount;
-#endif
register_sysctl_table(pty_root_table);

/* Now create the /dev/ptmx special device */
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index b0ad488..e881e9e 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -136,8 +136,6 @@ LIST_HEAD(tty_drivers); /* linked list of tty drivers */
DEFINE_MUTEX(tty_mutex);
EXPORT_SYMBOL(tty_mutex);

-static void initialize_tty_struct(struct tty_struct *tty);
-
static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
ssize_t redirected_tty_write(struct file *, const char __user *,
@@ -166,7 +164,7 @@ static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
* Locking: none
*/

-static struct tty_struct *alloc_tty_struct(void)
+struct tty_struct *alloc_tty_struct(void)
{
return kzalloc(sizeof(struct tty_struct), GFP_KERNEL);
}
@@ -180,7 +178,7 @@ static struct tty_struct *alloc_tty_struct(void)
* Locking: none. Must be called after tty is definitely unused
*/

-static inline void free_tty_struct(struct tty_struct *tty)
+void free_tty_struct(struct tty_struct *tty)
{
kfree(tty->write_buf);
tty_buffer_free_all(tty);
@@ -1227,22 +1225,70 @@ struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver, int idx)
}

/**
+ * tty_init_termios - helper for termios setup
+ * @tty: the tty to set up
+ *
+ * Initialise the termios structures for this tty. Thus runs under
+ * the tty_mutex currently so we can be relaxed about ordering.
+ */
+
+int tty_init_termios(struct tty_struct *tty)
+{
+ struct ktermios *tp, *ltp;
+ int idx = tty->index;
+
+ tp = tty->driver->termios[idx];
+ ltp = tty->driver->termios_locked[idx];
+ if (tp == NULL) {
+ WARN_ON(ltp != NULL);
+ tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
+ ltp = kzalloc(sizeof(struct ktermios), GFP_KERNEL);
+ if (tp == NULL || ltp == NULL) {
+ kfree(tp);
+ kfree(ltp);
+ return -ENOMEM;
+ }
+ memcpy(tp, &tty->driver->init_termios,
+ sizeof(struct ktermios));
+ tty->driver->termios[idx] = tp;
+ tty->driver->termios_locked[idx] = ltp;
+ }
+ tty->termios = tp;
+ tty->termios_locked = ltp;
+
+ /* Compatibility until drivers always set this */
+ tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
+ tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
+ return 0;
+}
+
+/**
* 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.
+ * will be set by the time this is called. This method is responsible
+ * for ensuring any need additional structures are allocated and
+ * configured.
*
* Locking: tty_mutex for now
*/
static int tty_driver_install_tty(struct tty_driver *driver,
struct tty_struct *tty)
{
+ int idx = tty->index;
+
if (driver->ops->install)
return driver->ops->install(driver, tty);
- driver->ttys[tty->index] = tty;
- return 0;
+
+ if (tty_init_termios(tty) == 0) {
+ tty_driver_kref_get(driver);
+ tty->count++;
+ driver->ttys[idx] = tty;
+ return 0;
+ }
+ return -ENOMEM;
}

/**
@@ -1327,9 +1373,7 @@ static int tty_reopen(struct tty_struct *tty)
struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
int first_ok)
{
- struct tty_struct *tty, *o_tty;
- struct ktermios *tp, **tp_loc, *o_tp, **o_tp_loc;
- struct ktermios *ltp, **ltp_loc, *o_ltp, **o_ltp_loc;
+ struct tty_struct *tty;
int retval;

/* check whether we're reopening an existing tty */
@@ -1361,118 +1405,17 @@ struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
if (!try_module_get(driver->owner))
return ERR_PTR(-ENODEV);

- o_tty = NULL;
- tp = o_tp = NULL;
- ltp = o_ltp = NULL;
-
tty = alloc_tty_struct();
if (!tty)
goto fail_no_mem;
- initialize_tty_struct(tty);
- tty->driver = driver;
- tty->ops = driver->ops;
- tty->index = idx;
- tty_line_name(driver, idx, tty->name);
-
- if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
- tp_loc = &tty->termios;
- ltp_loc = &tty->termios_locked;
- } else {
- tp_loc = &driver->termios[idx];
- ltp_loc = &driver->termios_locked[idx];
- }
-
- if (!*tp_loc) {
- tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
- if (!tp)
- goto free_mem_out;
- *tp = driver->init_termios;
- }
-
- if (!*ltp_loc) {
- ltp = kzalloc(sizeof(struct ktermios), GFP_KERNEL);
- if (!ltp)
- goto free_mem_out;
- }
-
- if (driver->type == TTY_DRIVER_TYPE_PTY) {
- o_tty = alloc_tty_struct();
- if (!o_tty)
- goto free_mem_out;
- if (!try_module_get(driver->other->owner)) {
- /* This cannot in fact currently happen */
- free_tty_struct(o_tty);
- o_tty = NULL;
- goto free_mem_out;
- }
- initialize_tty_struct(o_tty);
- o_tty->driver = driver->other;
- o_tty->ops = driver->ops;
- o_tty->index = idx;
- tty_line_name(driver->other, idx, o_tty->name);
-
- if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
- o_tp_loc = &o_tty->termios;
- o_ltp_loc = &o_tty->termios_locked;
- } else {
- o_tp_loc = &driver->other->termios[idx];
- o_ltp_loc = &driver->other->termios_locked[idx];
- }
-
- if (!*o_tp_loc) {
- o_tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
- if (!o_tp)
- goto free_mem_out;
- *o_tp = driver->other->init_termios;
- }
-
- if (!*o_ltp_loc) {
- o_ltp = kzalloc(sizeof(struct ktermios), GFP_KERNEL);
- if (!o_ltp)
- goto free_mem_out;
- }
-
- /*
- * Everything allocated ... set up the o_tty structure.
- */
- if (!(driver->other->flags & TTY_DRIVER_DEVPTS_MEM))
- driver->other->ttys[idx] = o_tty;
- if (!*o_tp_loc)
- *o_tp_loc = o_tp;
- if (!*o_ltp_loc)
- *o_ltp_loc = o_ltp;
- o_tty->termios = *o_tp_loc;
- o_tty->termios_locked = *o_ltp_loc;
- tty_driver_kref_get(driver->other);
- if (driver->subtype == PTY_TYPE_MASTER)
- o_tty->count++;
-
- /* Establish the links in both directions */
- tty->link = o_tty;
- o_tty->link = tty;
- }
-
- /*
- * 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.
- */
-
- if (!*tp_loc)
- *tp_loc = tp;
- if (!*ltp_loc)
- *ltp_loc = ltp;
- tty->termios = *tp_loc;
- tty->termios_locked = *ltp_loc;
- /* Compatibility until drivers always set this */
- tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
- tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
- tty_driver_kref_get(driver);
- tty->count++;
+ initialize_tty_struct(tty, driver, idx);

retval = tty_driver_install_tty(driver, tty);
- if (retval < 0)
- goto release_mem_out;
+ if (retval < 0) {
+ free_tty_struct(tty);
+ module_put(driver->owner);
+ return ERR_PTR(retval);
+ }

/*
* Structures all installed ... call the ldisc open routines.
@@ -1480,22 +1423,11 @@ struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
* to decrement the use counts, as release_tty doesn't care.
*/

- retval = tty_ldisc_setup(tty, o_tty);
+ retval = tty_ldisc_setup(tty, tty->link);
if (retval)
goto release_mem_out;
return tty;

- /* Release locally allocated memory ... nothing placed in slots */
-free_mem_out:
- kfree(o_tp);
- if (o_tty) {
- module_put(o_tty->driver->owner);
- free_tty_struct(o_tty);
- }
- kfree(ltp);
- kfree(tp);
- free_tty_struct(tty);
-
fail_no_mem:
module_put(driver->owner);
return ERR_PTR(-ENOMEM);
@@ -2852,7 +2784,8 @@ EXPORT_SYMBOL(do_SAK);
* Locking: none - tty in question must not be exposed at this point
*/

-static void initialize_tty_struct(struct tty_struct *tty)
+void initialize_tty_struct(struct tty_struct *tty,
+ struct tty_driver *driver, int idx)
{
memset(tty, 0, sizeof(struct tty_struct));
kref_init(&tty->kref);
@@ -2873,6 +2806,11 @@ static void initialize_tty_struct(struct tty_struct *tty)
spin_lock_init(&tty->ctrl_lock);
INIT_LIST_HEAD(&tty->tty_files);
INIT_WORK(&tty->SAK_work, do_SAK_work);
+
+ tty->driver = driver;
+ tty->ops = driver->ops;
+ tty->index = idx;
+ tty_line_name(driver, idx, tty->name);
}

/**
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 54523a3..3c7c757 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -401,9 +401,14 @@ extern dev_t tty_devnum(struct tty_struct *tty);
extern void proc_clear_tty(struct task_struct *p);
extern struct tty_struct *get_current_tty(void);
extern void tty_default_fops(struct file_operations *fops);
+extern struct tty_struct *alloc_tty_struct(void);
+extern void free_tty_struct(struct tty_struct *tty);
+extern void initialize_tty_struct(struct tty_struct *tty,
+ struct tty_driver *driver, int idx);
extern struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
int first_ok);
extern void tty_release_dev(struct file *filp);
+extern int tty_init_termios(struct tty_struct *tty);

extern struct mutex tty_mutex;