1 files changed, 777 insertions, 0 deletions

diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
new file mode 100644
index 000000000000..923a48585501
--- /dev/null
+++ b/drivers/tty/pty.c
@@ -0,0 +1,777 @@
+/*
+ *  linux/drivers/char/pty.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *
+ *  Added support for a Unix98-style ptmx device.
+ *    -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
+ *
+ *  When reading this code see also fs/devpts. In particular note that the
+ *  driver_data field is used by the devpts side as a binding to the devpts
+ *  inode.
+ */
+
+#include <linux/module.h>
+
+#include <linux/errno.h>
+#include <linux/interrupt.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/fcntl.h>
+#include <linux/sched.h>
+#include <linux/string.h>
+#include <linux/major.h>
+#include <linux/mm.h>
+#include <linux/init.h>
+#include <linux/smp_lock.h>
+#include <linux/sysctl.h>
+#include <linux/device.h>
+#include <linux/uaccess.h>
+#include <linux/bitops.h>
+#include <linux/devpts_fs.h>
+#include <linux/slab.h>
+
+#include <asm/system.h>
+
+#ifdef CONFIG_UNIX98_PTYS
+static struct tty_driver *ptm_driver;
+static struct tty_driver *pts_driver;
+#endif
+
+static void pty_close(struct tty_struct *tty, struct file *filp)
+{
+        BUG_ON(!tty);
+        if (tty->driver->subtype == PTY_TYPE_MASTER)
+                WARN_ON(tty->count > 1);
+        else {
+                if (tty->count > 2)
+                        return;
+        }
+        wake_up_interruptible(&tty->read_wait);
+        wake_up_interruptible(&tty->write_wait);
+        tty->packet = 0;
+        if (!tty->link)
+                return;
+        tty->link->packet = 0;
+        set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
+        wake_up_interruptible(&tty->link->read_wait);
+        wake_up_interruptible(&tty->link->write_wait);
+        if (tty->driver->subtype == PTY_TYPE_MASTER) {
+                set_bit(TTY_OTHER_CLOSED, &tty->flags);
+#ifdef CONFIG_UNIX98_PTYS
+                if (tty->driver == ptm_driver)
+                        devpts_pty_kill(tty->link);
+#endif
+                tty_unlock();
+                tty_vhangup(tty->link);
+                tty_lock();
+        }
+}
+
+/*
+ * The unthrottle routine is called by the line discipline to signal
+ * that it can receive more characters.  For PTY's, the TTY_THROTTLED
+ * flag is always set, to force the line discipline to always call the
+ * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
+ * characters in the queue.  This is necessary since each time this
+ * happens, we need to wake up any sleeping processes that could be
+ * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
+ * for the pty buffer to be drained.
+ */
+static void pty_unthrottle(struct tty_struct *tty)
+{
+        tty_wakeup(tty->link);
+        set_bit(TTY_THROTTLED, &tty->flags);
+}
+
+/**
+ *      pty_space       -       report space left for writing
+ *      @to: tty we are writing into
+ *
+ *      The tty buffers allow 64K but we sneak a peak and clip at 8K this
+ *      allows a lot of overspill room for echo and other fun messes to
+ *      be handled properly
+ */
+
+static int pty_space(struct tty_struct *to)
+{
+        int n = 8192 - to->buf.memory_used;
+        if (n < 0)
+                return 0;
+        return n;
+}
+
+/**
+ *      pty_write               -       write to a pty
+ *      @tty: the tty we write from
+ *      @buf: kernel buffer of data
+ *      @count: bytes to write
+ *
+ *      Our "hardware" write method. Data is coming from the ldisc which
+ *      may be in a non sleeping state. We simply throw this at the other
+ *      end of the link as if we were an IRQ handler receiving stuff for
+ *      the other side of the pty/tty pair.
+ */
+
+static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
+{
+        struct tty_struct *to = tty->link;
+
+        if (tty->stopped)
+                return 0;
+
+        if (c > 0) {
+                /* Stuff the data into the input queue of the other end */
+                c = tty_insert_flip_string(to, buf, c);
+                /* And shovel */
+                if (c) {
+                        tty_flip_buffer_push(to);
+                        tty_wakeup(tty);
+                }
+        }
+        return c;
+}
+
+/**
+ *      pty_write_room  -       write space
+ *      @tty: tty we are writing from
+ *
+ *      Report how many bytes the ldisc can send into the queue for
+ *      the other device.
+ */
+
+static int pty_write_room(struct tty_struct *tty)
+{
+        if (tty->stopped)
+                return 0;
+        return pty_space(tty->link);
+}
+
+/**
+ *      pty_chars_in_buffer     -       characters currently in our tx queue
+ *      @tty: our tty
+ *
+ *      Report how much we have in the transmit queue. As everything is
+ *      instantly at the other end this is easy to implement.
+ */
+
+static int pty_chars_in_buffer(struct tty_struct *tty)
+{
+        return 0;
+}
+
+/* Set the lock flag on a pty */
+static int pty_set_lock(struct tty_struct *tty, int __user *arg)
+{
+        int val;
+        if (get_user(val, arg))
+                return -EFAULT;
+        if (val)
+                set_bit(TTY_PTY_LOCK, &tty->flags);
+        else
+                clear_bit(TTY_PTY_LOCK, &tty->flags);
+        return 0;
+}
+
+/* Send a signal to the slave */
+static int pty_signal(struct tty_struct *tty, int sig)
+{
+        unsigned long flags;
+        struct pid *pgrp;
+
+        if (tty->link) {
+                spin_lock_irqsave(&tty->link->ctrl_lock, flags);
+                pgrp = get_pid(tty->link->pgrp);
+                spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
+
+                kill_pgrp(pgrp, sig, 1);
+                put_pid(pgrp);
+        }
+        return 0;
+}
+
+static void pty_flush_buffer(struct tty_struct *tty)
+{
+        struct tty_struct *to = tty->link;
+        unsigned long flags;
+
+        if (!to)
+                return;
+        /* tty_buffer_flush(to); FIXME */
+        if (to->packet) {
+                spin_lock_irqsave(&tty->ctrl_lock, flags);
+                tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
+                wake_up_interruptible(&to->read_wait);
+                spin_unlock_irqrestore(&tty->ctrl_lock, flags);
+        }
+}
+
+static int pty_open(struct tty_struct *tty, struct file *filp)
+{
+        int     retval = -ENODEV;
+
+        if (!tty || !tty->link)
+                goto out;
+
+        retval = -EIO;
+        if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
+                goto out;
+        if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
+                goto out;
+        if (tty->link->count != 1)
+                goto out;
+
+        clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
+        set_bit(TTY_THROTTLED, &tty->flags);
+        retval = 0;
+out:
+        return retval;
+}
+
+static void pty_set_termios(struct tty_struct *tty,
+                                        struct ktermios *old_termios)
+{
+        tty->termios->c_cflag &= ~(CSIZE | PARENB);
+        tty->termios->c_cflag |= (CS8 | CREAD);
+}
+
+/**
+ *      pty_do_resize           -       resize event
+ *      @tty: tty being resized
+ *      @ws: window size being set.
+ *
+ *      Update the termios variables and send the necessary signals to
+ *      peform a terminal resize correctly
+ */
+
+int pty_resize(struct tty_struct *tty,  struct winsize *ws)
+{
+        struct pid *pgrp, *rpgrp;
+        unsigned long flags;
+        struct tty_struct *pty = tty->link;
+
+        /* For a PTY we need to lock the tty side */
+        mutex_lock(&tty->termios_mutex);
+        if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
+                goto done;
+
+        /* Get the PID values and reference them so we can
+           avoid holding the tty ctrl lock while sending signals.
+           We need to lock these individually however. */
+
+        spin_lock_irqsave(&tty->ctrl_lock, flags);
+        pgrp = get_pid(tty->pgrp);
+        spin_unlock_irqrestore(&tty->ctrl_lock, flags);
+
+        spin_lock_irqsave(&pty->ctrl_lock, flags);
+        rpgrp = get_pid(pty->pgrp);
+        spin_unlock_irqrestore(&pty->ctrl_lock, flags);
+
+        if (pgrp)
+                kill_pgrp(pgrp, SIGWINCH, 1);
+        if (rpgrp != pgrp && rpgrp)
+                kill_pgrp(rpgrp, SIGWINCH, 1);
+
+        put_pid(pgrp);
+        put_pid(rpgrp);
+
+        tty->winsize = *ws;
+        pty->winsize = *ws;     /* Never used so will go away soon */
+done:
+        mutex_unlock(&tty->termios_mutex);
+        return 0;
+}
+
+/* Traditional BSD devices */
+#ifdef CONFIG_LEGACY_PTYS
+
+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 int pty_bsd_ioctl(struct tty_struct *tty, struct file *file,
+                         unsigned int cmd, unsigned long arg)
+{
+        switch (cmd) {
+        case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
+                return pty_set_lock(tty, (int __user *) arg);
+        case TIOCSIG:    /* Send signal to other side of pty */
+                return pty_signal(tty, (int) arg);
+        }
+        return -ENOIOCTLCMD;
+}
+
+static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
+module_param(legacy_count, int, 0);
+
+/*
+ * The master side of a pty can do TIOCSPTLCK and thus
+ * has pty_bsd_ioctl.
+ */
+static const struct tty_operations master_pty_ops_bsd = {
+        .install = pty_install,
+        .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,
+        .ioctl = pty_bsd_ioctl,
+        .resize = pty_resize
+};
+
+static const struct tty_operations slave_pty_ops_bsd = {
+        .install = pty_install,
+        .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,
+        .resize = pty_resize
+};
+
+static void __init legacy_pty_init(void)
+{
+        struct tty_driver *pty_driver, *pty_slave_driver;
+
+        if (legacy_count <= 0)
+                return;
+
+        pty_driver = alloc_tty_driver(legacy_count);
+        if (!pty_driver)
+                panic("Couldn't allocate pty driver");
+
+        pty_slave_driver = alloc_tty_driver(legacy_count);
+        if (!pty_slave_driver)
+                panic("Couldn't allocate pty slave driver");
+
+        pty_driver->owner = THIS_MODULE;
+        pty_driver->driver_name = "pty_master";
+        pty_driver->name = "pty";
+        pty_driver->major = PTY_MASTER_MAJOR;
+        pty_driver->minor_start = 0;
+        pty_driver->type = TTY_DRIVER_TYPE_PTY;
+        pty_driver->subtype = PTY_TYPE_MASTER;
+        pty_driver->init_termios = tty_std_termios;
+        pty_driver->init_termios.c_iflag = 0;
+        pty_driver->init_termios.c_oflag = 0;
+        pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
+        pty_driver->init_termios.c_lflag = 0;
+        pty_driver->init_termios.c_ispeed = 38400;
+        pty_driver->init_termios.c_ospeed = 38400;
+        pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
+        pty_driver->other = pty_slave_driver;
+        tty_set_operations(pty_driver, &master_pty_ops_bsd);
+
+        pty_slave_driver->owner = THIS_MODULE;
+        pty_slave_driver->driver_name = "pty_slave";
+        pty_slave_driver->name = "ttyp";
+        pty_slave_driver->major = PTY_SLAVE_MAJOR;
+        pty_slave_driver->minor_start = 0;
+        pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
+        pty_slave_driver->subtype = PTY_TYPE_SLAVE;
+        pty_slave_driver->init_termios = tty_std_termios;
+        pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
+        pty_slave_driver->init_termios.c_ispeed = 38400;
+        pty_slave_driver->init_termios.c_ospeed = 38400;
+        pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS |
+                                        TTY_DRIVER_REAL_RAW;
+        pty_slave_driver->other = pty_driver;
+        tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
+
+        if (tty_register_driver(pty_driver))
+                panic("Couldn't register pty driver");
+        if (tty_register_driver(pty_slave_driver))
+                panic("Couldn't register pty slave driver");
+}
+#else
+static inline void legacy_pty_init(void) { }
+#endif
+
+/* Unix98 devices */
+#ifdef CONFIG_UNIX98_PTYS
+/*
+ * sysctl support for setting limits on the number of Unix98 ptys allocated.
+ * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
+ */
+int pty_limit = NR_UNIX98_PTY_DEFAULT;
+static int pty_limit_min;
+static int pty_limit_max = NR_UNIX98_PTY_MAX;
+static int pty_count;
+
+static struct cdev ptmx_cdev;
+
+static struct ctl_table pty_table[] = {
+        {
+                .procname       = "max",
+                .maxlen         = sizeof(int),
+                .mode           = 0644,
+                .data           = &pty_limit,
+                .proc_handler   = proc_dointvec_minmax,
+                .extra1         = &pty_limit_min,
+                .extra2         = &pty_limit_max,
+        }, {
+                .procname       = "nr",
+                .maxlen         = sizeof(int),
+                .mode           = 0444,
+                .data           = &pty_count,
+                .proc_handler   = proc_dointvec,
+        }, 
+        {}
+};
+
+static struct ctl_table pty_kern_table[] = {
+        {
+                .procname       = "pty",
+                .mode           = 0555,
+                .child          = pty_table,
+        },
+        {}
+};
+
+static struct ctl_table pty_root_table[] = {
+        {
+                .procname       = "kernel",
+                .mode           = 0555,
+                .child          = pty_kern_table,
+        },
+        {}
+};
+
+
+static int pty_unix98_ioctl(struct tty_struct *tty, struct file *file,
+                            unsigned int cmd, unsigned long arg)
+{
+        switch (cmd) {
+        case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
+                return pty_set_lock(tty, (int __user *)arg);
+        case TIOCGPTN: /* Get PT Number */
+                return put_user(tty->index, (unsigned int __user *)arg);
+        case TIOCSIG:    /* Send signal to other side of pty */
+                return pty_signal(tty, (int) arg);
+        }
+
+        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,
+                struct inode *ptm_inode, int idx)
+{
+        struct tty_struct *tty = devpts_get_tty(ptm_inode, 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,
+                struct inode *pts_inode, int idx)
+{
+        struct tty_struct *tty = devpts_get_tty(pts_inode, idx);
+        /* Master must be open before slave */
+        if (!tty)
+                return ERR_PTR(-EIO);
+        return 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);
+}
+
+/* We have no need to install and remove our tty objects as devpts does all
+   the work for us */
+
+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 = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
+        if (tty->termios == NULL)
+                goto free_mem_out;
+        *tty->termios = driver->init_termios;
+        tty->termios_locked = tty->termios + 1;
+
+        o_tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
+        if (o_tty->termios == NULL)
+                goto free_mem_out;
+        *o_tty->termios = driver->other->init_termios;
+        o_tty->termios_locked = o_tty->termios + 1;
+
+        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);
+        return -ENOMEM;
+}
+
+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_unix98_install,
+        .remove = pty_unix98_remove,
+        .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,
+        .ioctl = pty_unix98_ioctl,
+        .shutdown = pty_unix98_shutdown,
+        .resize = pty_resize
+};
+
+static const struct tty_operations pty_unix98_ops = {
+        .lookup = pts_unix98_lookup,
+        .install = pty_unix98_install,
+        .remove = pty_unix98_remove,
+        .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,
+        .shutdown = pty_unix98_shutdown
+};
+
+/**
+ *      ptmx_open               -       open a unix 98 pty master
+ *      @inode: inode of device file
+ *      @filp: file pointer to tty
+ *
+ *      Allocate a unix98 pty master device from the ptmx driver.
+ *
+ *      Locking: tty_mutex protects the init_dev work. tty->count should
+ *              protect the rest.
+ *              allocated_ptys_lock handles the list of free pty numbers
+ */
+
+static int ptmx_open(struct inode *inode, struct file *filp)
+{
+        struct tty_struct *tty;
+        int retval;
+        int index;
+
+        nonseekable_open(inode, filp);
+
+        /* find a device that is not in use. */
+        tty_lock();
+        index = devpts_new_index(inode);
+        tty_unlock();
+        if (index < 0)
+                return index;
+
+        mutex_lock(&tty_mutex);
+        tty_lock();
+        tty = tty_init_dev(ptm_driver, index, 1);
+        mutex_unlock(&tty_mutex);
+
+        if (IS_ERR(tty)) {
+                retval = PTR_ERR(tty);
+                goto out;
+        }
+
+        set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
+
+        retval = tty_add_file(tty, filp);
+        if (retval)
+                goto out;
+
+        retval = devpts_pty_new(inode, tty->link);
+        if (retval)
+                goto out1;
+
+        retval = ptm_driver->ops->open(tty, filp);
+        if (retval)
+                goto out2;
+out1:
+        tty_unlock();
+        return retval;
+out2:
+        tty_unlock();
+        tty_release(inode, filp);
+        return retval;
+out:
+        devpts_kill_index(inode, index);
+        tty_unlock();
+        return retval;
+}
+
+static struct file_operations ptmx_fops;
+
+static void __init unix98_pty_init(void)
+{
+        ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
+        if (!ptm_driver)
+                panic("Couldn't allocate Unix98 ptm driver");
+        pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
+        if (!pts_driver)
+                panic("Couldn't allocate Unix98 pts driver");
+
+        ptm_driver->owner = THIS_MODULE;
+        ptm_driver->driver_name = "pty_master";
+        ptm_driver->name = "ptm";
+        ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
+        ptm_driver->minor_start = 0;
+        ptm_driver->type = TTY_DRIVER_TYPE_PTY;
+        ptm_driver->subtype = PTY_TYPE_MASTER;
+        ptm_driver->init_termios = tty_std_termios;
+        ptm_driver->init_termios.c_iflag = 0;
+        ptm_driver->init_termios.c_oflag = 0;
+        ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
+        ptm_driver->init_termios.c_lflag = 0;
+        ptm_driver->init_termios.c_ispeed = 38400;
+        ptm_driver->init_termios.c_ospeed = 38400;
+        ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
+                TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
+        ptm_driver->other = pts_driver;
+        tty_set_operations(ptm_driver, &ptm_unix98_ops);
+
+        pts_driver->owner = THIS_MODULE;
+        pts_driver->driver_name = "pty_slave";
+        pts_driver->name = "pts";
+        pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
+        pts_driver->minor_start = 0;
+        pts_driver->type = TTY_DRIVER_TYPE_PTY;
+        pts_driver->subtype = PTY_TYPE_SLAVE;
+        pts_driver->init_termios = tty_std_termios;
+        pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
+        pts_driver->init_termios.c_ispeed = 38400;
+        pts_driver->init_termios.c_ospeed = 38400;
+        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_unix98_ops);
+
+        if (tty_register_driver(ptm_driver))
+                panic("Couldn't register Unix98 ptm driver");
+        if (tty_register_driver(pts_driver))
+                panic("Couldn't register Unix98 pts driver");
+
+        register_sysctl_table(pty_root_table);
+
+        /* Now create the /dev/ptmx special device */
+        tty_default_fops(&ptmx_fops);
+        ptmx_fops.open = ptmx_open;
+
+        cdev_init(&ptmx_cdev, &ptmx_fops);
+        if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
+            register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
+                panic("Couldn't register /dev/ptmx driver\n");
+        device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
+}
+
+#else
+static inline void unix98_pty_init(void) { }
+#endif
+
+static int __init pty_init(void)
+{
+        legacy_pty_init();
+        unix98_pty_init();
+        return 0;
+}
+module_init(pty_init);