Merge branch 'topic/core-cleanup' into for-linus
[safe/jmp/linux-2.6] / drivers / char / tty_io.c
index 7323168..d71f0fc 100644 (file)
@@ -49,7 +49,7 @@
  * implement CONFIG_VT and generalize console device interface.
  *     -- Marko Kohtala <Marko.Kohtala@hut.fi>, March 97
  *
- * Rewrote init_dev and release_dev to eliminate races.
+ * Rewrote tty_init_dev and tty_release_dev to eliminate races.
  *     -- Bill Hawes <whawes@star.net>, June 97
  *
  * Added devfs support.
@@ -136,20 +136,12 @@ LIST_HEAD(tty_drivers);                   /* linked list of tty drivers */
 DEFINE_MUTEX(tty_mutex);
 EXPORT_SYMBOL(tty_mutex);
 
-#ifdef CONFIG_UNIX98_PTYS
-extern struct tty_driver *ptm_driver;  /* Unix98 pty masters; for /dev/ptmx */
-static int ptmx_open(struct inode *, struct file *);
-#endif
-
-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 *,
                                                        size_t, loff_t *);
 static unsigned int tty_poll(struct file *, poll_table *);
 static int tty_open(struct inode *, struct file *);
-static int tty_release(struct inode *, struct file *);
 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
 #ifdef CONFIG_COMPAT
 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
@@ -171,7 +163,7 @@ 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);
 }
@@ -185,7 +177,7 @@ 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);
@@ -281,7 +273,7 @@ static struct tty_driver *get_tty_driver(dev_t device, int *index)
                if (device < base || device >= base + p->num)
                        continue;
                *index = device - base;
-               return p;
+               return tty_driver_kref_get(p);
        }
        return NULL;
 }
@@ -302,7 +294,7 @@ struct tty_driver *tty_find_polling_driver(char *name, int *line)
        struct tty_driver *p, *res = NULL;
        int tty_line = 0;
        int len;
-       char *str;
+       char *str, *stp;
 
        for (str = name; *str; str++)
                if ((*str >= '0' && *str <= '9') || *str == ',')
@@ -318,14 +310,15 @@ struct tty_driver *tty_find_polling_driver(char *name, int *line)
        list_for_each_entry(p, &tty_drivers, tty_drivers) {
                if (strncmp(name, p->name, len) != 0)
                        continue;
-               if (*str == ',')
-                       str++;
-               if (*str == '\0')
-                       str = NULL;
+               stp = str;
+               if (*stp == ',')
+                       stp++;
+               if (*stp == '\0')
+                       stp = NULL;
 
                if (tty_line >= 0 && tty_line <= p->num && p->ops &&
-                   p->ops->poll_init && !p->ops->poll_init(p, tty_line, str)) {
-                       res = p;
+                   p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) {
+                       res = tty_driver_kref_get(p);
                        *line = tty_line;
                        break;
                }
@@ -425,20 +418,6 @@ static const struct file_operations tty_fops = {
        .fasync         = tty_fasync,
 };
 
-#ifdef CONFIG_UNIX98_PTYS
-static const struct file_operations ptmx_fops = {
-       .llseek         = no_llseek,
-       .read           = tty_read,
-       .write          = tty_write,
-       .poll           = tty_poll,
-       .unlocked_ioctl = tty_ioctl,
-       .compat_ioctl   = tty_compat_ioctl,
-       .open           = ptmx_open,
-       .release        = tty_release,
-       .fasync         = tty_fasync,
-};
-#endif
-
 static const struct file_operations console_fops = {
        .llseek         = no_llseek,
        .read           = tty_read,
@@ -485,49 +464,12 @@ void tty_wakeup(struct tty_struct *tty)
                        tty_ldisc_deref(ld);
                }
        }
-       wake_up_interruptible(&tty->write_wait);
+       wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
 }
 
 EXPORT_SYMBOL_GPL(tty_wakeup);
 
 /**
- *     tty_ldisc_flush -       flush line discipline queue
- *     @tty: tty
- *
- *     Flush the line discipline queue (if any) for this tty. If there
- *     is no line discipline active this is a no-op.
- */
-
-void tty_ldisc_flush(struct tty_struct *tty)
-{
-       struct tty_ldisc *ld = tty_ldisc_ref(tty);
-       if (ld) {
-               if (ld->ops->flush_buffer)
-                       ld->ops->flush_buffer(tty);
-               tty_ldisc_deref(ld);
-       }
-       tty_buffer_flush(tty);
-}
-
-EXPORT_SYMBOL_GPL(tty_ldisc_flush);
-
-/**
- *     tty_reset_termios       -       reset terminal state
- *     @tty: tty to reset
- *
- *     Restore a terminal to the driver default state
- */
-
-static void tty_reset_termios(struct tty_struct *tty)
-{
-       mutex_lock(&tty->termios_mutex);
-       *tty->termios = tty->driver->init_termios;
-       tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
-       tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
-       mutex_unlock(&tty->termios_mutex);
-}
-
-/**
  *     do_tty_hangup           -       actual handler for hangup events
  *     @work: tty device
  *
@@ -556,15 +498,13 @@ static void do_tty_hangup(struct work_struct *work)
        struct file *cons_filp = NULL;
        struct file *filp, *f = NULL;
        struct task_struct *p;
-       struct tty_ldisc *ld;
        int    closecount = 0, n;
        unsigned long flags;
+       int refs = 0;
 
        if (!tty)
                return;
 
-       /* inuse_filps is protected by the single kernel lock */
-       lock_kernel();
 
        spin_lock(&redirect_lock);
        if (redirect && redirect->private_data == tty) {
@@ -573,7 +513,10 @@ static void do_tty_hangup(struct work_struct *work)
        }
        spin_unlock(&redirect_lock);
 
+       /* inuse_filps is protected by the single kernel lock */
+       lock_kernel();
        check_tty_count(tty, "do_tty_hangup");
+
        file_list_lock();
        /* This breaks for file handles being sent over AF_UNIX sockets ? */
        list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) {
@@ -586,47 +529,19 @@ static void do_tty_hangup(struct work_struct *work)
                filp->f_op = &hung_up_tty_fops;
        }
        file_list_unlock();
-       /*
-        * FIXME! What are the locking issues here? This may me overdoing
-        * things... This question is especially important now that we've
-        * removed the irqlock.
-        */
-       ld = tty_ldisc_ref(tty);
-       if (ld != NULL) {
-               /* We may have no line discipline at this point */
-               if (ld->ops->flush_buffer)
-                       ld->ops->flush_buffer(tty);
-               tty_driver_flush_buffer(tty);
-               if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) &&
-                   ld->ops->write_wakeup)
-                       ld->ops->write_wakeup(tty);
-               if (ld->ops->hangup)
-                       ld->ops->hangup(tty);
-       }
-       /*
-        * FIXME: Once we trust the LDISC code better we can wait here for
-        * ldisc completion and fix the driver call race
-        */
-       wake_up_interruptible(&tty->write_wait);
-       wake_up_interruptible(&tty->read_wait);
-       /*
-        * Shutdown the current line discipline, and reset it to
-        * N_TTY.
-        */
-       if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
-               tty_reset_termios(tty);
-       /* Defer ldisc switch */
-       /* tty_deferred_ldisc_switch(N_TTY);
 
-         This should get done automatically when the port closes and
-         tty_release is called */
+       tty_ldisc_hangup(tty);
 
        read_lock(&tasklist_lock);
        if (tty->session) {
                do_each_pid_task(tty->session, PIDTYPE_SID, p) {
                        spin_lock_irq(&p->sighand->siglock);
-                       if (p->signal->tty == tty)
+                       if (p->signal->tty == tty) {
                                p->signal->tty = NULL;
+                               /* We defer the dereferences outside fo
+                                  the tasklist lock */
+                               refs++;
+                       }
                        if (!p->signal->leader) {
                                spin_unlock_irq(&p->sighand->siglock);
                                continue;
@@ -644,14 +559,21 @@ static void do_tty_hangup(struct work_struct *work)
        read_unlock(&tasklist_lock);
 
        spin_lock_irqsave(&tty->ctrl_lock, flags);
-       tty->flags = 0;
+       clear_bit(TTY_THROTTLED, &tty->flags);
+       clear_bit(TTY_PUSH, &tty->flags);
+       clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
        put_pid(tty->session);
        put_pid(tty->pgrp);
        tty->session = NULL;
        tty->pgrp = NULL;
        tty->ctrl_status = 0;
+       set_bit(TTY_HUPPED, &tty->flags);
        spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 
+       /* Account for the p->signal references we killed */
+       while (refs--)
+               tty_kref_put(tty);
+
        /*
         * If one of the devices matches a console pointer, we
         * cannot just call hangup() because that will cause
@@ -671,10 +593,7 @@ static void do_tty_hangup(struct work_struct *work)
         * can't yet guarantee all that.
         */
        set_bit(TTY_HUPPED, &tty->flags);
-       if (ld) {
-               tty_ldisc_enable(tty);
-               tty_ldisc_deref(ld);
-       }
+       tty_ldisc_enable(tty);
        unlock_kernel();
        if (f)
                fput(f);
@@ -721,6 +640,23 @@ void tty_vhangup(struct tty_struct *tty)
 EXPORT_SYMBOL(tty_vhangup);
 
 /**
+ *     tty_vhangup_self        -       process vhangup for own ctty
+ *
+ *     Perform a vhangup on the current controlling tty
+ */
+
+void tty_vhangup_self(void)
+{
+       struct tty_struct *tty;
+
+       tty = get_current_tty();
+       if (tty) {
+               tty_vhangup(tty);
+               tty_kref_put(tty);
+       }
+}
+
+/**
  *     tty_hung_up_p           -       was tty hung up
  *     @filp: file pointer of tty
  *
@@ -772,17 +708,17 @@ void disassociate_ctty(int on_exit)
        struct tty_struct *tty;
        struct pid *tty_pgrp = NULL;
 
+       if (!current->signal->leader)
+               return;
 
-       mutex_lock(&tty_mutex);
        tty = get_current_tty();
        if (tty) {
                tty_pgrp = get_pid(tty->pgrp);
                lock_kernel();
-               mutex_unlock(&tty_mutex);
-               /* XXX: here we race, there is nothing protecting tty */
                if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)
                        tty_vhangup(tty);
                unlock_kernel();
+               tty_kref_put(tty);
        } else if (on_exit) {
                struct pid *old_pgrp;
                spin_lock_irq(&current->sighand->siglock);
@@ -794,7 +730,6 @@ void disassociate_ctty(int on_exit)
                        kill_pgrp(old_pgrp, SIGCONT, on_exit);
                        put_pid(old_pgrp);
                }
-               mutex_unlock(&tty_mutex);
                return;
        }
        if (tty_pgrp) {
@@ -809,8 +744,6 @@ void disassociate_ctty(int on_exit)
        current->signal->tty_old_pgrp = NULL;
        spin_unlock_irq(&current->sighand->siglock);
 
-       mutex_lock(&tty_mutex);
-       /* It is possible that do_tty_hangup has free'd this tty */
        tty = get_current_tty();
        if (tty) {
                unsigned long flags;
@@ -820,13 +753,13 @@ void disassociate_ctty(int on_exit)
                tty->session = NULL;
                tty->pgrp = NULL;
                spin_unlock_irqrestore(&tty->ctrl_lock, flags);
+               tty_kref_put(tty);
        } else {
 #ifdef TTY_DEBUG_HANGUP
                printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
                       " = NULL", tty);
 #endif
        }
-       mutex_unlock(&tty_mutex);
 
        /* Now clear signal->tty under the lock */
        read_lock(&tasklist_lock);
@@ -842,8 +775,7 @@ void no_tty(void)
 {
        struct task_struct *tsk = current;
        lock_kernel();
-       if (tsk->signal->leader)
-               disassociate_ctty(0);
+       disassociate_ctty(0);
        unlock_kernel();
        proc_clear_tty(tsk);
 }
@@ -879,7 +811,7 @@ void stop_tty(struct tty_struct *tty)
        if (tty->link && tty->link->packet) {
                tty->ctrl_status &= ~TIOCPKT_START;
                tty->ctrl_status |= TIOCPKT_STOP;
-               wake_up_interruptible(&tty->link->read_wait);
+               wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
        }
        spin_unlock_irqrestore(&tty->ctrl_lock, flags);
        if (tty->ops->stop)
@@ -913,7 +845,7 @@ void start_tty(struct tty_struct *tty)
        if (tty->link && tty->link->packet) {
                tty->ctrl_status &= ~TIOCPKT_STOP;
                tty->ctrl_status |= TIOCPKT_START;
-               wake_up_interruptible(&tty->link->read_wait);
+               wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
        }
        spin_unlock_irqrestore(&tty->ctrl_lock, flags);
        if (tty->ops->start)
@@ -970,7 +902,7 @@ static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
 void tty_write_unlock(struct tty_struct *tty)
 {
        mutex_unlock(&tty->atomic_write_lock);
-       wake_up_interruptible(&tty->write_wait);
+       wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
 }
 
 int tty_write_lock(struct tty_struct *tty, int ndelay)
@@ -1026,19 +958,19 @@ static inline ssize_t do_tty_write(
 
        /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
        if (tty->write_cnt < chunk) {
-               unsigned char *buf;
+               unsigned char *buf_chunk;
 
                if (chunk < 1024)
                        chunk = 1024;
 
-               buf = kmalloc(chunk, GFP_KERNEL);
-               if (!buf) {
+               buf_chunk = kmalloc(chunk, GFP_KERNEL);
+               if (!buf_chunk) {
                        ret = -ENOMEM;
                        goto out;
                }
                kfree(tty->write_buf);
                tty->write_cnt = chunk;
-               tty->write_buf = buf;
+               tty->write_buf = buf_chunk;
        }
 
        /* Do the write .. */
@@ -1072,6 +1004,33 @@ out:
        return ret;
 }
 
+/**
+ * tty_write_message - write a message to a certain tty, not just the console.
+ * @tty: the destination tty_struct
+ * @msg: the message to write
+ *
+ * This is used for messages that need to be redirected to a specific tty.
+ * We don't put it into the syslog queue right now maybe in the future if
+ * really needed.
+ *
+ * We must still hold the BKL and test the CLOSING flag for the moment.
+ */
+
+void tty_write_message(struct tty_struct *tty, char *msg)
+{
+       if (tty) {
+               mutex_lock(&tty->atomic_write_lock);
+               lock_kernel();
+               if (tty->ops->write && !test_bit(TTY_CLOSING, &tty->flags)) {
+                       unlock_kernel();
+                       tty->ops->write(tty, msg, strlen(msg));
+               } else
+                       unlock_kernel();
+               tty_write_unlock(tty);
+       }
+       return;
+}
+
 
 /**
  *     tty_write               -       write method for tty device file
@@ -1086,9 +1045,7 @@ out:
  *             Locks the line discipline as required
  *             Writes to the tty driver are serialized by the atomic_write_lock
  *     and are then processed in chunks to the device. The line discipline
- *     write method will not be involked in parallel for each device
- *             The line discipline write method is called under the big
- *     kernel lock for historical reasons. New code should not rely on this.
+ *     write method will not be invoked in parallel for each device.
  */
 
 static ssize_t tty_write(struct file *file, const char __user *buf,
@@ -1162,7 +1119,7 @@ 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
@@ -1178,10 +1135,158 @@ static void tty_line_name(struct tty_driver *driver, int index, char *p)
 }
 
 /**
- *     init_dev                -       initialise a tty device
+ *     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.
+ *
+ *     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
+ */
+static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
+               struct inode *inode, int idx)
+{
+       struct tty_struct *tty;
+
+       if (driver->ops->lookup)
+               return driver->ops->lookup(driver, inode, idx);
+
+       tty = driver->ttys[idx];
+       return tty;
+}
+
+/**
+ *     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;
+       int idx = tty->index;
+
+       tp = tty->driver->termios[idx];
+       if (tp == NULL) {
+               tp = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
+               if (tp == NULL)
+                       return -ENOMEM;
+               memcpy(tp, &tty->driver->init_termios,
+                                               sizeof(struct ktermios));
+               tty->driver->termios[idx] = tp;
+       }
+       tty->termios = tp;
+       tty->termios_locked = tp + 1;
+
+       /* 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;
+}
+EXPORT_SYMBOL_GPL(tty_init_termios);
+
+/**
+ *     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. 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;
+       int ret;
+
+       if (driver->ops->install) {
+               lock_kernel();
+               ret = driver->ops->install(driver, tty);
+               unlock_kernel();
+               return ret;
+       }
+
+       if (tty_init_termios(tty) == 0) {
+               lock_kernel();
+               tty_driver_kref_get(driver);
+               tty->count++;
+               driver->ttys[idx] = tty;
+               unlock_kernel();
+               return 0;
+       }
+       return -ENOMEM;
+}
+
+/**
+ *     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.
+ *
+ *     Locking: tty_mutex must be held from the time the tty was found
+ *              till this open completes.
+ */
+static int tty_reopen(struct tty_struct *tty)
+{
+       struct tty_driver *driver = tty->driver;
+
+       if (test_bit(TTY_CLOSING, &tty->flags))
+               return -EIO;
+
+       if (driver->type == TTY_DRIVER_TYPE_PTY &&
+           driver->subtype == PTY_TYPE_MASTER) {
+               /*
+                * special case for PTY masters: only one open permitted,
+                * and the slave side open count is incremented as well.
+                */
+               if (tty->count)
+                       return -EIO;
+
+               tty->link->count++;
+       }
+       tty->count++;
+       tty->driver = driver; /* N.B. why do this every time?? */
+
+       mutex_lock(&tty->ldisc_mutex);
+       WARN_ON(!test_bit(TTY_LDISC, &tty->flags));
+       mutex_unlock(&tty->ldisc_mutex);
+
+       return 0;
+}
+
+/**
+ *     tty_init_dev            -       initialise a tty device
  *     @driver: tty driver we are opening a device on
  *     @idx: device index
- *     @tty: returned tty structure
+ *     @ret_tty: returned tty structure
+ *     @first_ok: ok to open a new device (used by ptmx)
  *
  *     Prepare a tty device. This may not be a "new" clean device but
  *     could also be an active device. The pty drivers require special
@@ -1201,37 +1306,20 @@ static void tty_line_name(struct tty_driver *driver, int index, char *p)
  * relaxed for the (most common) case of reopening a tty.
  */
 
-static int init_dev(struct tty_driver *driver, int idx,
-       struct tty_struct **ret_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;
-       int retval = 0;
+       struct tty_struct *tty;
+       int retval;
 
-       /* 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) {
-                       retval = -EIO;
-                       goto end_init;
-               }
-               /*
-                * It's safe from now on because init_dev() is called with
-                * tty_mutex held and release_dev() won't change tty->count
-                * or tty->flags without having to grab tty_mutex
-                */
-               if (tty && driver->subtype == PTY_TYPE_MASTER)
-                       tty = tty->link;
-       } else {
-               tty = driver->ttys[idx];
+       lock_kernel();
+       /* Check if pty master is being opened multiple times */
+       if (driver->subtype == PTY_TYPE_MASTER &&
+               (driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) {
+               unlock_kernel();
+               return ERR_PTR(-EIO);
        }
-       if (tty) goto fast_track;
+       unlock_kernel();
 
        /*
         * First time open is complex, especially for PTY devices.
@@ -1241,189 +1329,70 @@ static int init_dev(struct tty_driver *driver, int idx,
         * and locked termios may be retained.)
         */
 
-       if (!try_module_get(driver->owner)) {
-               retval = -ENODEV;
-               goto end_init;
-       }
-
-       o_tty = NULL;
-       tp = o_tp = NULL;
-       ltp = o_ltp = NULL;
+       if (!try_module_get(driver->owner))
+               return ERR_PTR(-ENODEV);
 
        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;
-       }
+       initialize_tty_struct(tty, driver, idx);
 
-       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;
-               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;
-               driver->other->refcount++;
-               if (driver->subtype == PTY_TYPE_MASTER)
-                       o_tty->count++;
-
-               /* Establish the links in both directions */
-               tty->link   = o_tty;
-               o_tty->link = tty;
+       retval = tty_driver_install_tty(driver, tty);
+       if (retval < 0) {
+               free_tty_struct(tty);
+               module_put(driver->owner);
+               return ERR_PTR(retval);
        }
 
        /*
-        * 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 (!(driver->flags & TTY_DRIVER_DEVPTS_MEM))
-               driver->ttys[idx] = tty;
-
-       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);
-       driver->refcount++;
-       tty->count++;
-
-       /*
         * Structures all installed ... call the ldisc open routines.
         * If we fail here just call release_tty to clean up.  No need
         * 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;
-        goto success;
-
-       /*
-        * This fast open can be used if the tty is already open.
-        * No memory is allocated, and the only failures are from
-        * attempting to open a closing tty or attempting multiple
-        * opens on a pty master.
-        */
-fast_track:
-       if (test_bit(TTY_CLOSING, &tty->flags)) {
-               retval = -EIO;
-               goto end_init;
-       }
-       if (driver->type == TTY_DRIVER_TYPE_PTY &&
-           driver->subtype == PTY_TYPE_MASTER) {
-               /*
-                * special case for PTY masters: only one open permitted,
-                * and the slave side open count is incremented as well.
-                */
-               if (tty->count) {
-                       retval = -EIO;
-                       goto end_init;
-               }
-               tty->link->count++;
-       }
-       tty->count++;
-       tty->driver = driver; /* N.B. why do this every time?? */
-
-       /* FIXME */
-       if (!test_bit(TTY_LDISC, &tty->flags))
-               printk(KERN_ERR "init_dev but no ldisc\n");
-success:
-       *ret_tty = tty;
-
-       /* All paths come through here to release the mutex */
-end_init:
-       return retval;
-
-       /* Release locally allocated memory ... nothing placed in slots */
-free_mem_out:
-       kfree(o_tp);
-       if (o_tty)
-               free_tty_struct(o_tty);
-       kfree(ltp);
-       kfree(tp);
-       free_tty_struct(tty);
+       return tty;
 
 fail_no_mem:
        module_put(driver->owner);
-       retval = -ENOMEM;
-       goto end_init;
+       return ERR_PTR(-ENOMEM);
 
        /* call the tty release_tty routine to clean out this slot */
 release_mem_out:
        if (printk_ratelimit())
-               printk(KERN_INFO "init_dev: ldisc open failed, "
+               printk(KERN_INFO "tty_init_dev: ldisc open failed, "
                                 "clearing slot %d\n", idx);
+       lock_kernel();
        release_tty(tty, idx);
-       goto end_init;
+       unlock_kernel();
+       return ERR_PTR(retval);
 }
 
+void tty_free_termios(struct tty_struct *tty)
+{
+       struct ktermios *tp;
+       int idx = tty->index;
+       /* Kill this flag and push into drivers for locking etc */
+       if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
+               /* FIXME: Locking on ->termios array */
+               tp = tty->termios;
+               tty->driver->termios[idx] = NULL;
+               kfree(tp);
+       }
+}
+EXPORT_SYMBOL(tty_free_termios);
+
+void tty_shutdown(struct tty_struct *tty)
+{
+       tty_driver_remove_tty(tty->driver, tty);
+       tty_free_termios(tty);
+}
+EXPORT_SYMBOL(tty_shutdown);
+
 /**
  *     release_one_tty         -       release tty structure memory
+ *     @kref: kref of tty we are obliterating
  *
  *     Releases memory associated with a tty structure, and clears out the
  *     driver table slots. This function is called when a device is no longer
@@ -1433,39 +1402,62 @@ release_mem_out:
  *             tty_mutex - sometimes only
  *             takes the file list lock internally when working on the list
  *     of ttys that the driver keeps.
- *             FIXME: should we require tty_mutex is held here ??
+ *
+ *     This method gets called from a work queue so that the driver private
+ *     cleanup ops can sleep (needed for USB at least)
  */
-static void release_one_tty(struct tty_struct *tty, int idx)
+static void release_one_tty(struct work_struct *work)
 {
-       int devpts = tty->driver->flags & TTY_DRIVER_DEVPTS_MEM;
-       struct ktermios *tp;
-
-       if (!devpts)
-               tty->driver->ttys[idx] = NULL;
-
-       if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
-               tp = tty->termios;
-               if (!devpts)
-                       tty->driver->termios[idx] = NULL;
-               kfree(tp);
-
-               tp = tty->termios_locked;
-               if (!devpts)
-                       tty->driver->termios_locked[idx] = NULL;
-               kfree(tp);
-       }
+       struct tty_struct *tty =
+               container_of(work, struct tty_struct, hangup_work);
+       struct tty_driver *driver = tty->driver;
 
+       if (tty->ops->cleanup)
+               tty->ops->cleanup(tty);
 
        tty->magic = 0;
-       tty->driver->refcount--;
+       tty_driver_kref_put(driver);
+       module_put(driver->owner);
 
        file_list_lock();
        list_del_init(&tty->tty_files);
        file_list_unlock();
 
+       put_pid(tty->pgrp);
+       put_pid(tty->session);
        free_tty_struct(tty);
 }
 
+static void queue_release_one_tty(struct kref *kref)
+{
+       struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
+
+       if (tty->ops->shutdown)
+               tty->ops->shutdown(tty);
+       else
+               tty_shutdown(tty);
+
+       /* The hangup queue is now free so we can reuse it rather than
+          waste a chunk of memory for each port */
+       INIT_WORK(&tty->hangup_work, release_one_tty);
+       schedule_work(&tty->hangup_work);
+}
+
+/**
+ *     tty_kref_put            -       release a tty kref
+ *     @tty: tty device
+ *
+ *     Release a reference to a tty device and if need be let the kref
+ *     layer destruct the object for us
+ */
+
+void tty_kref_put(struct tty_struct *tty)
+{
+       if (tty)
+               kref_put(&tty->kref, queue_release_one_tty);
+}
+EXPORT_SYMBOL(tty_kref_put);
+
 /**
  *     release_tty             -       release tty structure memory
  *
@@ -1477,18 +1469,29 @@ static void release_one_tty(struct tty_struct *tty, int idx)
  *             takes the file list lock internally when working on the list
  *     of ttys that the driver keeps.
  *             FIXME: should we require tty_mutex is held here ??
+ *
  */
 static void release_tty(struct tty_struct *tty, int idx)
 {
-       struct tty_driver *driver = tty->driver;
+       /* This should always be true but check for the moment */
+       WARN_ON(tty->index != idx);
 
        if (tty->link)
-               release_one_tty(tty->link, idx);
-       release_one_tty(tty, idx);
-       module_put(driver->owner);
+               tty_kref_put(tty->link);
+       tty_kref_put(tty);
 }
 
-/*
+/**
+ *     tty_release             -       vfs callback for close
+ *     @inode: inode of tty
+ *     @filp: file pointer for handle to tty
+ *
+ *     Called the last time each file handle is closed that references
+ *     this tty. There may however be several such references.
+ *
+ *     Locking:
+ *             Takes bkl. See tty_release_dev
+ *
  * Even releasing the tty structures is a tricky business.. We have
  * to be very careful that the structures are all released at the
  * same time, as interrupts might otherwise get the wrong pointers.
@@ -1496,7 +1499,8 @@ static void release_tty(struct tty_struct *tty, int idx)
  * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
  * lead to double frees or releasing memory still in use.
  */
-static void release_dev(struct file *filp)
+
+int tty_release(struct inode *inode, struct file *filp)
 {
        struct tty_struct *tty, *o_tty;
        int     pty_master, tty_closing, o_tty_closing, do_sleep;
@@ -1505,11 +1509,11 @@ static void release_dev(struct file *filp)
        char    buf[64];
 
        tty = (struct tty_struct *)filp->private_data;
-       if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode,
-                                                       "release_dev"))
-               return;
+       if (tty_paranoia_check(tty, inode, "tty_release_dev"))
+               return 0;
 
-       check_tty_count(tty, "release_dev");
+       lock_kernel();
+       check_tty_count(tty, "tty_release_dev");
 
        tty_fasync(-1, filp, 0);
 
@@ -1521,33 +1525,30 @@ static void release_dev(struct file *filp)
 
 #ifdef TTY_PARANOIA_CHECK
        if (idx < 0 || idx >= tty->driver->num) {
-               printk(KERN_DEBUG "release_dev: bad idx when trying to "
+               printk(KERN_DEBUG "tty_release_dev: bad idx when trying to "
                                  "free (%s)\n", tty->name);
-               return;
+               unlock_kernel();
+               return 0;
        }
-       if (!(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
+       if (!devpts) {
                if (tty != tty->driver->ttys[idx]) {
-                       printk(KERN_DEBUG "release_dev: driver.table[%d] not tty "
+                       unlock_kernel();
+                       printk(KERN_DEBUG "tty_release_dev: driver.table[%d] not tty "
                               "for (%s)\n", idx, tty->name);
-                       return;
+                       return 0;
                }
                if (tty->termios != tty->driver->termios[idx]) {
-                       printk(KERN_DEBUG "release_dev: driver.termios[%d] not termios "
+                       unlock_kernel();
+                       printk(KERN_DEBUG "tty_release_dev: driver.termios[%d] not termios "
                               "for (%s)\n",
                               idx, tty->name);
-                       return;
-               }
-               if (tty->termios_locked != tty->driver->termios_locked[idx]) {
-                       printk(KERN_DEBUG "release_dev: driver.termios_locked[%d] not "
-                              "termios_locked for (%s)\n",
-                              idx, tty->name);
-                       return;
+                       return 0;
                }
        }
 #endif
 
 #ifdef TTY_DEBUG_HANGUP
-       printk(KERN_DEBUG "release_dev of %s (tty count=%d)...",
+       printk(KERN_DEBUG "tty_release_dev of %s (tty count=%d)...",
               tty_name(tty, buf), tty->count);
 #endif
 
@@ -1555,33 +1556,30 @@ static void release_dev(struct file *filp)
        if (tty->driver->other &&
             !(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
                if (o_tty != tty->driver->other->ttys[idx]) {
-                       printk(KERN_DEBUG "release_dev: other->table[%d] "
+                       unlock_kernel();
+                       printk(KERN_DEBUG "tty_release_dev: other->table[%d] "
                                          "not o_tty for (%s)\n",
                               idx, tty->name);
-                       return;
+                       return 0 ;
                }
                if (o_tty->termios != tty->driver->other->termios[idx]) {
-                       printk(KERN_DEBUG "release_dev: other->termios[%d] "
+                       unlock_kernel();
+                       printk(KERN_DEBUG "tty_release_dev: other->termios[%d] "
                                          "not o_termios for (%s)\n",
                               idx, tty->name);
-                       return;
-               }
-               if (o_tty->termios_locked !=
-                     tty->driver->other->termios_locked[idx]) {
-                       printk(KERN_DEBUG "release_dev: other->termios_locked["
-                                         "%d] not o_termios_locked for (%s)\n",
-                              idx, tty->name);
-                       return;
+                       return 0;
                }
                if (o_tty->link != tty) {
-                       printk(KERN_DEBUG "release_dev: bad pty pointers\n");
-                       return;
+                       unlock_kernel();
+                       printk(KERN_DEBUG "tty_release_dev: bad pty pointers\n");
+                       return 0;
                }
        }
 #endif
        if (tty->ops->close)
                tty->ops->close(tty, filp);
 
+       unlock_kernel();
        /*
         * Sanity check: if tty->count is going to zero, there shouldn't be
         * any waiters on tty->read_wait or tty->write_wait.  We test the
@@ -1604,6 +1602,7 @@ static void release_dev(struct file *filp)
                   opens on /dev/tty */
 
                mutex_lock(&tty_mutex);
+               lock_kernel();
                tty_closing = tty->count <= 1;
                o_tty_closing = o_tty &&
                        (o_tty->count <= (pty_master ? 1 : 0));
@@ -1611,29 +1610,30 @@ static void release_dev(struct file *filp)
 
                if (tty_closing) {
                        if (waitqueue_active(&tty->read_wait)) {
-                               wake_up(&tty->read_wait);
+                               wake_up_poll(&tty->read_wait, POLLIN);
                                do_sleep++;
                        }
                        if (waitqueue_active(&tty->write_wait)) {
-                               wake_up(&tty->write_wait);
+                               wake_up_poll(&tty->write_wait, POLLOUT);
                                do_sleep++;
                        }
                }
                if (o_tty_closing) {
                        if (waitqueue_active(&o_tty->read_wait)) {
-                               wake_up(&o_tty->read_wait);
+                               wake_up_poll(&o_tty->read_wait, POLLIN);
                                do_sleep++;
                        }
                        if (waitqueue_active(&o_tty->write_wait)) {
-                               wake_up(&o_tty->write_wait);
+                               wake_up_poll(&o_tty->write_wait, POLLOUT);
                                do_sleep++;
                        }
                }
                if (!do_sleep)
                        break;
 
-               printk(KERN_WARNING "release_dev: %s: read/write wait queue "
+               printk(KERN_WARNING "tty_release_dev: %s: read/write wait queue "
                                    "active!\n", tty_name(tty, buf));
+               unlock_kernel();
                mutex_unlock(&tty_mutex);
                schedule();
        }
@@ -1645,14 +1645,14 @@ static void release_dev(struct file *filp)
         */
        if (pty_master) {
                if (--o_tty->count < 0) {
-                       printk(KERN_WARNING "release_dev: bad pty slave count "
+                       printk(KERN_WARNING "tty_release_dev: bad pty slave count "
                                            "(%d) for %s\n",
                               o_tty->count, tty_name(o_tty, buf));
                        o_tty->count = 0;
                }
        }
        if (--tty->count < 0) {
-               printk(KERN_WARNING "release_dev: bad tty->count (%d) for %s\n",
+               printk(KERN_WARNING "tty_release_dev: bad tty->count (%d) for %s\n",
                       tty->count, tty_name(tty, buf));
                tty->count = 0;
        }
@@ -1697,8 +1697,10 @@ static void release_dev(struct file *filp)
        mutex_unlock(&tty_mutex);
 
        /* check whether both sides are closing ... */
-       if (!tty_closing || (o_tty && !o_tty_closing))
-               return;
+       if (!tty_closing || (o_tty && !o_tty_closing)) {
+               unlock_kernel();
+               return 0;
+       }
 
 #ifdef TTY_DEBUG_HANGUP
        printk(KERN_DEBUG "freeing tty structure...");
@@ -1715,7 +1717,9 @@ static void release_dev(struct file *filp)
 
        /* Make this pty number available for reallocation */
        if (devpts)
-               devpts_kill_index(idx);
+               devpts_kill_index(inode, idx);
+       unlock_kernel();
+       return 0;
 }
 
 /**
@@ -1734,19 +1738,19 @@ static void release_dev(struct file *filp)
  *     The termios state of a pty is reset on first open so that
  *     settings don't persist across reuse.
  *
- *     Locking: tty_mutex protects tty, get_tty_driver and init_dev work.
+ *     Locking: tty_mutex protects tty, get_tty_driver and tty_init_dev work.
  *              tty->count should protect the rest.
  *              ->siglock protects ->signal/->sighand
  */
 
-static int __tty_open(struct inode *inode, struct file *filp)
+static int tty_open(struct inode *inode, struct file *filp)
 {
-       struct tty_struct *tty;
+       struct tty_struct *tty = NULL;
        int noctty, retval;
        struct tty_driver *driver;
        int index;
        dev_t device = inode->i_rdev;
-       unsigned short saved_flags = filp->f_flags;
+       unsigned saved_flags = filp->f_flags;
 
        nonseekable_open(inode, filp);
 
@@ -1756,50 +1760,79 @@ retry_open:
        retval = 0;
 
        mutex_lock(&tty_mutex);
+       lock_kernel();
 
        if (device == MKDEV(TTYAUX_MAJOR, 0)) {
                tty = get_current_tty();
                if (!tty) {
+                       unlock_kernel();
                        mutex_unlock(&tty_mutex);
                        return -ENXIO;
                }
-               driver = tty->driver;
+               driver = tty_driver_kref_get(tty->driver);
                index = tty->index;
                filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
                /* noctty = 1; */
+               /* FIXME: Should we take a driver reference ? */
+               tty_kref_put(tty);
                goto got_driver;
        }
 #ifdef CONFIG_VT
        if (device == MKDEV(TTY_MAJOR, 0)) {
                extern struct tty_driver *console_driver;
-               driver = console_driver;
+               driver = tty_driver_kref_get(console_driver);
                index = fg_console;
                noctty = 1;
                goto got_driver;
        }
 #endif
        if (device == MKDEV(TTYAUX_MAJOR, 1)) {
-               driver = console_device(&index);
-               if (driver) {
-                       /* Don't let /dev/console block */
-                       filp->f_flags |= O_NONBLOCK;
-                       noctty = 1;
-                       goto got_driver;
+               struct tty_driver *console_driver = console_device(&index);
+               if (console_driver) {
+                       driver = tty_driver_kref_get(console_driver);
+                       if (driver) {
+                               /* Don't let /dev/console block */
+                               filp->f_flags |= O_NONBLOCK;
+                               noctty = 1;
+                               goto got_driver;
+                       }
                }
+               unlock_kernel();
                mutex_unlock(&tty_mutex);
                return -ENODEV;
        }
 
        driver = get_tty_driver(device, &index);
        if (!driver) {
+               unlock_kernel();
                mutex_unlock(&tty_mutex);
                return -ENODEV;
        }
 got_driver:
-       retval = init_dev(driver, index, &tty);
+       if (!tty) {
+               /* check whether we're reopening an existing tty */
+               tty = tty_driver_lookup_tty(driver, inode, index);
+
+               if (IS_ERR(tty)) {
+                       unlock_kernel();
+                       mutex_unlock(&tty_mutex);
+                       return PTR_ERR(tty);
+               }
+       }
+
+       if (tty) {
+               retval = tty_reopen(tty);
+               if (retval)
+                       tty = ERR_PTR(retval);
+       } else
+               tty = tty_init_dev(driver, index, 0);
+
        mutex_unlock(&tty_mutex);
-       if (retval)
-               return retval;
+       tty_driver_kref_put(driver);
+       if (IS_ERR(tty)) {
+               unlock_kernel();
+               return PTR_ERR(tty);
+       }
 
        filp->private_data = tty;
        file_move(filp, &tty->tty_files);
@@ -1827,21 +1860,29 @@ got_driver:
                printk(KERN_DEBUG "error %d in opening %s...", retval,
                       tty->name);
 #endif
-               release_dev(filp);
-               if (retval != -ERESTARTSYS)
+               tty_release(inode, filp);
+               if (retval != -ERESTARTSYS) {
+                       unlock_kernel();
                        return retval;
-               if (signal_pending(current))
+               }
+               if (signal_pending(current)) {
+                       unlock_kernel();
                        return retval;
+               }
                schedule();
                /*
                 * Need to reset f_op in case a hangup happened.
                 */
                if (filp->f_op == &hung_up_tty_fops)
                        filp->f_op = &tty_fops;
+               unlock_kernel();
                goto retry_open;
        }
+       unlock_kernel();
+
 
        mutex_lock(&tty_mutex);
+       lock_kernel();
        spin_lock_irq(&current->sighand->siglock);
        if (!noctty &&
            current->signal->leader &&
@@ -1849,106 +1890,12 @@ got_driver:
            tty->session == NULL)
                __proc_set_tty(current, tty);
        spin_unlock_irq(&current->sighand->siglock);
-       mutex_unlock(&tty_mutex);
-       return 0;
-}
-
-/* BKL pushdown: scary code avoidance wrapper */
-static int tty_open(struct inode *inode, struct file *filp)
-{
-       int ret;
-
-       lock_kernel();
-       ret = __tty_open(inode, filp);
        unlock_kernel();
-       return ret;
-}
-
-
-
-#ifdef CONFIG_UNIX98_PTYS
-/**
- *     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 theinit_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. */
-       index = devpts_new_index();
-       if (index < 0)
-               return index;
-
-       mutex_lock(&tty_mutex);
-       retval = init_dev(ptm_driver, index, &tty);
        mutex_unlock(&tty_mutex);
-
-       if (retval)
-               goto out;
-
-       set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
-       filp->private_data = tty;
-       file_move(filp, &tty->tty_files);
-
-       retval = devpts_pty_new(tty->link);
-       if (retval)
-               goto out1;
-
-       check_tty_count(tty, "ptmx_open");
-       retval = ptm_driver->ops->open(tty, filp);
-       if (!retval)
-               return 0;
-out1:
-       release_dev(filp);
-       return retval;
-out:
-       devpts_kill_index(index);
-       return retval;
-}
-
-static int ptmx_open(struct inode *inode, struct file *filp)
-{
-       int ret;
-
-       lock_kernel();
-       ret = __ptmx_open(inode, filp);
-       unlock_kernel();
-       return ret;
+       return 0;
 }
-#endif
 
-/**
- *     tty_release             -       vfs callback for close
- *     @inode: inode of tty
- *     @filp: file pointer for handle to tty
- *
- *     Called the last time each file handle is closed that references
- *     this tty. There may however be several such references.
- *
- *     Locking:
- *             Takes bkl. See release_dev
- */
 
-static int tty_release(struct inode *inode, struct file *filp)
-{
-       lock_kernel();
-       release_dev(filp);
-       unlock_kernel();
-       return 0;
-}
 
 /**
  *     tty_poll        -       check tty status
@@ -2007,8 +1954,10 @@ static int tty_fasync(int fd, struct file *filp, int on)
                        pid = task_pid(current);
                        type = PIDTYPE_PID;
                }
+               get_pid(pid);
                spin_unlock_irqrestore(&tty->ctrl_lock, flags);
                retval = __f_setown(filp, pid, type, 0);
+               put_pid(pid);
                if (retval)
                        goto out;
        } else {
@@ -2047,6 +1996,7 @@ static int tiocsti(struct tty_struct *tty, char __user *p)
                return -EPERM;
        if (get_user(ch, p))
                return -EFAULT;
+       tty_audit_tiocsti(tty, ch);
        ld = tty_ldisc_ref_wait(tty);
        ld->ops->receive_buf(tty, &ch, &mbz, 1);
        tty_ldisc_deref(ld);
@@ -2078,49 +2028,41 @@ static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
 /**
  *     tty_do_resize           -       resize event
  *     @tty: tty being resized
- *     @real_tty: real tty (not the same as tty if using a pty/tty pair)
  *     @rows: rows (character)
  *     @cols: cols (character)
  *
- *     Update the termios variables and send the neccessary signals to
+ *     Update the termios variables and send the necessary signals to
  *     peform a terminal resize correctly
  */
 
-int tty_do_resize(struct tty_struct *tty, struct tty_struct *real_tty,
-                                       struct winsize *ws)
+int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
 {
-       struct pid *pgrp, *rpgrp;
+       struct pid *pgrp;
        unsigned long flags;
 
-       /* For a PTY we need to lock the tty side */
-       mutex_lock(&real_tty->termios_mutex);
+       /* Lock the tty */
+       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 */
        spin_lock_irqsave(&tty->ctrl_lock, flags);
        pgrp = get_pid(tty->pgrp);
-       rpgrp = get_pid(real_tty->pgrp);
        spin_unlock_irqrestore(&tty->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;
-       real_tty->winsize = *ws;
 done:
-       mutex_unlock(&real_tty->termios_mutex);
+       mutex_unlock(&tty->termios_mutex);
        return 0;
 }
 
 /**
  *     tiocswinsz              -       implement window size set ioctl
- *     @tty; tty
+ *     @tty; tty side of tty
  *     @arg: user buffer for result
  *
  *     Copies the user idea of the window size to the kernel. Traditionally
@@ -2133,17 +2075,16 @@ done:
  *     then calls into the default method.
  */
 
-static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty,
-       struct winsize __user *arg)
+static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
 {
        struct winsize tmp_ws;
        if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
                return -EFAULT;
 
        if (tty->ops->resize)
-               return tty->ops->resize(tty, real_tty, &tmp_ws);
+               return tty->ops->resize(tty, &tmp_ws);
        else
-               return tty_do_resize(tty, real_tty, &tmp_ws);
+               return tty_do_resize(tty, &tmp_ws);
 }
 
 /**
@@ -2189,7 +2130,7 @@ static int tioccons(struct file *file)
  *     the generic functionality existed. This piece of history is preserved
  *     in the expected tty API of posix OS's.
  *
- *     Locking: none, the open fle handle ensures it won't go away.
+ *     Locking: none, the open file handle ensures it won't go away.
  */
 
 static int fionbio(struct file *file, int __user *p)
@@ -2199,13 +2140,12 @@ static int fionbio(struct file *file, int __user *p)
        if (get_user(nonblock, p))
                return -EFAULT;
 
-       /* file->f_flags is still BKL protected in the fs layer - vomit */
-       lock_kernel();
+       spin_lock(&file->f_lock);
        if (nonblock)
                file->f_flags |= O_NONBLOCK;
        else
                file->f_flags &= ~O_NONBLOCK;
-       unlock_kernel();
+       spin_unlock(&file->f_lock);
        return 0;
 }
 
@@ -2403,9 +2343,7 @@ static int tiocsetd(struct tty_struct *tty, int __user *p)
        if (get_user(ldisc, p))
                return -EFAULT;
 
-       lock_kernel();
        ret = tty_set_ldisc(tty, ldisc);
-       unlock_kernel();
 
        return ret;
 }
@@ -2518,6 +2456,24 @@ static int tty_tiocmset(struct tty_struct *tty, struct file *file, unsigned int
        return tty->ops->tiocmset(tty, file, set, clear);
 }
 
+struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
+{
+       if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
+           tty->driver->subtype == PTY_TYPE_MASTER)
+               tty = tty->link;
+       return tty;
+}
+EXPORT_SYMBOL(tty_pair_get_tty);
+
+struct tty_struct *tty_pair_get_pty(struct tty_struct *tty)
+{
+       if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
+           tty->driver->subtype == PTY_TYPE_MASTER)
+           return tty;
+       return tty->link;
+}
+EXPORT_SYMBOL(tty_pair_get_pty);
+
 /*
  * Split this up, as gcc can choke on it otherwise..
  */
@@ -2533,11 +2489,7 @@ long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
        if (tty_paranoia_check(tty, inode, "tty_ioctl"))
                return -EINVAL;
 
-       real_tty = tty;
-       if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
-           tty->driver->subtype == PTY_TYPE_MASTER)
-               real_tty = tty->link;
-
+       real_tty = tty_pair_get_tty(tty);
 
        /*
         * Factor out some common prep work
@@ -2566,9 +2518,9 @@ long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
        case TIOCSTI:
                return tiocsti(tty, p);
        case TIOCGWINSZ:
-               return tiocgwinsz(tty, p);
+               return tiocgwinsz(real_tty, p);
        case TIOCSWINSZ:
-               return tiocswinsz(tty, real_tty, p);
+               return tiocswinsz(real_tty, p);
        case TIOCCONS:
                return real_tty != tty ? -EINVAL : tioccons(file);
        case FIONBIO:
@@ -2593,7 +2545,7 @@ long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
        case TIOCGSID:
                return tiocgsid(tty, real_tty, p);
        case TIOCGETD:
-               return put_user(tty->ldisc.ops->num, (int __user *)p);
+               return put_user(tty->ldisc->ops->num, (int __user *)p);
        case TIOCSETD:
                return tiocsetd(tty, p);
        /*
@@ -2719,7 +2671,7 @@ void __do_SAK(struct tty_struct *tty)
        /* Kill the entire session */
        do_each_pid_task(session, PIDTYPE_SID, p) {
                printk(KERN_NOTICE "SAK: killed process %d"
-                       " (%s): task_session_nr(p)==tty->session\n",
+                       " (%s): task_session(p)==tty->session\n",
                        task_pid_nr(p), p->comm);
                send_sig(SIGKILL, p, 1);
        } while_each_pid_task(session, PIDTYPE_SID, p);
@@ -2729,7 +2681,7 @@ void __do_SAK(struct tty_struct *tty)
        do_each_thread(g, p) {
                if (p->signal->tty == tty) {
                        printk(KERN_NOTICE "SAK: killed process %d"
-                           " (%s): task_session_nr(p)==tty->session\n",
+                           " (%s): task_session(p)==tty->session\n",
                            task_pid_nr(p), p->comm);
                        send_sig(SIGKILL, p, 1);
                        continue;
@@ -2795,9 +2747,11 @@ 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);
        tty->magic = TTY_MAGIC;
        tty_ldisc_init(tty);
        tty->session = NULL;
@@ -2806,15 +2760,23 @@ static void initialize_tty_struct(struct tty_struct *tty)
        tty->buf.head = tty->buf.tail = NULL;
        tty_buffer_init(tty);
        mutex_init(&tty->termios_mutex);
+       mutex_init(&tty->ldisc_mutex);
        init_waitqueue_head(&tty->write_wait);
        init_waitqueue_head(&tty->read_wait);
        INIT_WORK(&tty->hangup_work, do_tty_hangup);
        mutex_init(&tty->atomic_read_lock);
        mutex_init(&tty->atomic_write_lock);
+       mutex_init(&tty->output_lock);
+       mutex_init(&tty->echo_lock);
        spin_lock_init(&tty->read_lock);
        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);
 }
 
 /**
@@ -2835,10 +2797,9 @@ int tty_put_char(struct tty_struct *tty, unsigned char ch)
                return tty->ops->put_char(tty, ch);
        return tty->ops->write(tty, &ch, 1);
 }
-
 EXPORT_SYMBOL_GPL(tty_put_char);
 
-static struct class *tty_class;
+struct class *tty_class;
 
 /**
  *     tty_register_device - register a tty device
@@ -2876,8 +2837,9 @@ struct device *tty_register_device(struct tty_driver *driver, unsigned index,
        else
                tty_line_name(driver, index, name);
 
-       return device_create_drvdata(tty_class, device, dev, NULL, name);
+       return device_create(tty_class, device, dev, NULL, name);
 }
+EXPORT_SYMBOL(tty_register_device);
 
 /**
  *     tty_unregister_device - unregister a tty device
@@ -2895,8 +2857,6 @@ void tty_unregister_device(struct tty_driver *driver, unsigned index)
        device_destroy(tty_class,
                MKDEV(driver->major, driver->minor_start) + index);
 }
-
-EXPORT_SYMBOL(tty_register_device);
 EXPORT_SYMBOL(tty_unregister_device);
 
 struct tty_driver *alloc_tty_driver(int lines)
@@ -2905,27 +2865,65 @@ struct tty_driver *alloc_tty_driver(int lines)
 
        driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
        if (driver) {
+               kref_init(&driver->kref);
                driver->magic = TTY_DRIVER_MAGIC;
                driver->num = lines;
                /* later we'll move allocation of tables here */
        }
        return driver;
 }
+EXPORT_SYMBOL(alloc_tty_driver);
 
-void put_tty_driver(struct tty_driver *driver)
+static void destruct_tty_driver(struct kref *kref)
 {
+       struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
+       int i;
+       struct ktermios *tp;
+       void *p;
+
+       if (driver->flags & TTY_DRIVER_INSTALLED) {
+               /*
+                * Free the termios and termios_locked structures because
+                * we don't want to get memory leaks when modular tty
+                * drivers are removed from the kernel.
+                */
+               for (i = 0; i < driver->num; i++) {
+                       tp = driver->termios[i];
+                       if (tp) {
+                               driver->termios[i] = NULL;
+                               kfree(tp);
+                       }
+                       if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
+                               tty_unregister_device(driver, i);
+               }
+               p = driver->ttys;
+               proc_tty_unregister_driver(driver);
+               driver->ttys = NULL;
+               driver->termios = NULL;
+               kfree(p);
+               cdev_del(&driver->cdev);
+       }
        kfree(driver);
 }
 
+void tty_driver_kref_put(struct tty_driver *driver)
+{
+       kref_put(&driver->kref, destruct_tty_driver);
+}
+EXPORT_SYMBOL(tty_driver_kref_put);
+
 void tty_set_operations(struct tty_driver *driver,
                        const struct tty_operations *op)
 {
        driver->ops = op;
 };
+EXPORT_SYMBOL(tty_set_operations);
 
-EXPORT_SYMBOL(alloc_tty_driver);
+void put_tty_driver(struct tty_driver *d)
+{
+       tty_driver_kref_put(d);
+}
 EXPORT_SYMBOL(put_tty_driver);
-EXPORT_SYMBOL(tty_set_operations);
 
 /*
  * Called by a tty driver to register itself.
@@ -2937,11 +2935,8 @@ int tty_register_driver(struct tty_driver *driver)
        dev_t dev;
        void **p = NULL;
 
-       if (driver->flags & TTY_DRIVER_INSTALLED)
-               return 0;
-
        if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM) && driver->num) {
-               p = kzalloc(driver->num * 3 * sizeof(void *), GFP_KERNEL);
+               p = kzalloc(driver->num * 2 * sizeof(void *), GFP_KERNEL);
                if (!p)
                        return -ENOMEM;
        }
@@ -2965,12 +2960,9 @@ int tty_register_driver(struct tty_driver *driver)
        if (p) {
                driver->ttys = (struct tty_struct **)p;
                driver->termios = (struct ktermios **)(p + driver->num);
-               driver->termios_locked = (struct ktermios **)
-                                                       (p + driver->num * 2);
        } else {
                driver->ttys = NULL;
                driver->termios = NULL;
-               driver->termios_locked = NULL;
        }
 
        cdev_init(&driver->cdev, &tty_fops);
@@ -2979,7 +2971,7 @@ int tty_register_driver(struct tty_driver *driver)
        if (error) {
                unregister_chrdev_region(dev, driver->num);
                driver->ttys = NULL;
-               driver->termios = driver->termios_locked = NULL;
+               driver->termios = NULL;
                kfree(p);
                return error;
        }
@@ -2993,6 +2985,7 @@ int tty_register_driver(struct tty_driver *driver)
                    tty_register_device(driver, i, NULL);
        }
        proc_tty_register_driver(driver);
+       driver->flags |= TTY_DRIVER_INSTALLED;
        return 0;
 }
 
@@ -3003,46 +2996,19 @@ EXPORT_SYMBOL(tty_register_driver);
  */
 int tty_unregister_driver(struct tty_driver *driver)
 {
-       int i;
-       struct ktermios *tp;
-       void *p;
-
+#if 0
+       /* FIXME */
        if (driver->refcount)
                return -EBUSY;
-
+#endif
        unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
                                driver->num);
        mutex_lock(&tty_mutex);
        list_del(&driver->tty_drivers);
        mutex_unlock(&tty_mutex);
-
-       /*
-        * Free the termios and termios_locked structures because
-        * we don't want to get memory leaks when modular tty
-        * drivers are removed from the kernel.
-        */
-       for (i = 0; i < driver->num; i++) {
-               tp = driver->termios[i];
-               if (tp) {
-                       driver->termios[i] = NULL;
-                       kfree(tp);
-               }
-               tp = driver->termios_locked[i];
-               if (tp) {
-                       driver->termios_locked[i] = NULL;
-                       kfree(tp);
-               }
-               if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
-                       tty_unregister_device(driver, i);
-       }
-       p = driver->ttys;
-       proc_tty_unregister_driver(driver);
-       driver->ttys = NULL;
-       driver->termios = driver->termios_locked = NULL;
-       kfree(p);
-       cdev_del(&driver->cdev);
        return 0;
 }
+
 EXPORT_SYMBOL(tty_unregister_driver);
 
 dev_t tty_devnum(struct tty_struct *tty)
@@ -3053,9 +3019,13 @@ EXPORT_SYMBOL(tty_devnum);
 
 void proc_clear_tty(struct task_struct *p)
 {
-       spin_lock_irq(&p->sighand->siglock);
+       unsigned long flags;
+       struct tty_struct *tty;
+       spin_lock_irqsave(&p->sighand->siglock, flags);
+       tty = p->signal->tty;
        p->signal->tty = NULL;
-       spin_unlock_irq(&p->sighand->siglock);
+       spin_unlock_irqrestore(&p->sighand->siglock, flags);
+       tty_kref_put(tty);
 }
 
 /* Called under the sighand lock */
@@ -3071,9 +3041,13 @@ static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
                tty->pgrp = get_pid(task_pgrp(tsk));
                spin_unlock_irqrestore(&tty->ctrl_lock, flags);
                tty->session = get_pid(task_session(tsk));
+               if (tsk->signal->tty) {
+                       printk(KERN_DEBUG "tty not NULL!!\n");
+                       tty_kref_put(tsk->signal->tty);
+               }
        }
        put_pid(tsk->signal->tty_old_pgrp);
-       tsk->signal->tty = tty;
+       tsk->signal->tty = tty_kref_get(tty);
        tsk->signal->tty_old_pgrp = NULL;
 }
 
@@ -3087,18 +3061,20 @@ static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
 struct tty_struct *get_current_tty(void)
 {
        struct tty_struct *tty;
-       WARN_ON_ONCE(!mutex_is_locked(&tty_mutex));
-       tty = current->signal->tty;
-       /*
-        * session->tty can be changed/cleared from under us, make sure we
-        * issue the load. The obtained pointer, when not NULL, is valid as
-        * long as we hold tty_mutex.
-        */
-       barrier();
+       unsigned long flags;
+
+       spin_lock_irqsave(&current->sighand->siglock, flags);
+       tty = tty_kref_get(current->signal->tty);
+       spin_unlock_irqrestore(&current->sighand->siglock, flags);
        return tty;
 }
 EXPORT_SYMBOL_GPL(get_current_tty);
 
+void tty_default_fops(struct file_operations *fops)
+{
+       *fops = tty_fops;
+}
+
 /*
  * Initialize the console device. This is called *early*, so
  * we can't necessarily depend on lots of kernel help here.
@@ -3123,11 +3099,22 @@ void __init console_init(void)
        }
 }
 
+static char *tty_devnode(struct device *dev, mode_t *mode)
+{
+       if (!mode)
+               return NULL;
+       if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
+           dev->devt == MKDEV(TTYAUX_MAJOR, 2))
+               *mode = 0666;
+       return NULL;
+}
+
 static int __init tty_class_init(void)
 {
        tty_class = class_create(THIS_MODULE, "tty");
        if (IS_ERR(tty_class))
                return PTR_ERR(tty_class);
+       tty_class->devnode = tty_devnode;
        return 0;
 }
 
@@ -3136,12 +3123,6 @@ postcore_initcall(tty_class_init);
 /* 3/2004 jmc: why do these devices exist? */
 
 static struct cdev tty_cdev, console_cdev;
-#ifdef CONFIG_UNIX98_PTYS
-static struct cdev ptmx_cdev;
-#endif
-#ifdef CONFIG_VT
-static struct cdev vc0_cdev;
-#endif
 
 /*
  * Ok, now we can initialize the rest of the tty devices and can count
@@ -3153,32 +3134,18 @@ static int __init tty_init(void)
        if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
            register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
                panic("Couldn't register /dev/tty driver\n");
-       device_create_drvdata(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL,
+       device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL,
                              "tty");
 
        cdev_init(&console_cdev, &console_fops);
        if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
            register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
                panic("Couldn't register /dev/console driver\n");
-       device_create_drvdata(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 1), NULL,
+       device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 1), NULL,
                              "console");
 
-#ifdef CONFIG_UNIX98_PTYS
-       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_drvdata(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
-#endif
-
 #ifdef CONFIG_VT
-       cdev_init(&vc0_cdev, &console_fops);
-       if (cdev_add(&vc0_cdev, MKDEV(TTY_MAJOR, 0), 1) ||
-           register_chrdev_region(MKDEV(TTY_MAJOR, 0), 1, "/dev/vc/0") < 0)
-               panic("Couldn't register /dev/tty0 driver\n");
-       device_create_drvdata(tty_class, NULL, MKDEV(TTY_MAJOR, 0), NULL, "tty0");
-
-       vty_init();
+       vty_init(&console_fops);
 #endif
        return 0;
 }