tty: Make get_current_tty use a kref
[safe/jmp/linux-2.6] / drivers / char / tty_io.c
index c57b1f4..4c0e4ed 100644 (file)
@@ -19,7 +19,7 @@
  * Also restructured routines so that there is more of a separation
  * between the high-level tty routines (tty_io.c and tty_ioctl.c) and
  * the low-level tty routines (serial.c, pty.c, console.c).  This
- * makes for cleaner and more compact code.  -TYT, 9/17/92 
+ * makes for cleaner and more compact code.  -TYT, 9/17/92
  *
  * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
  * which can be dynamically activated and de-activated by the line
@@ -41,7 +41,7 @@
  *
  * New TIOCLINUX variants added.
  *     -- mj@k332.feld.cvut.cz, 19-Nov-95
- * 
+ *
  * Restrict vt switching via ioctl()
  *      -- grif@cs.ucr.edu, 5-Dec-95
  *
@@ -62,7 +62,8 @@
  *      -- Russell King <rmk@arm.linux.org.uk>
  *
  * Move do_SAK() into process context.  Less stack use in devfs functions.
- * alloc_tty_struct() always uses kmalloc() -- Andrew Morton <andrewm@uow.edu.eu> 17Mar01
+ * alloc_tty_struct() always uses kmalloc()
+ *                      -- Andrew Morton <andrewm@uow.edu.eu> 17Mar01
  */
 
 #include <linux/types.h>
@@ -77,6 +78,7 @@
 #include <linux/tty_flip.h>
 #include <linux/devpts_fs.h>
 #include <linux/file.h>
+#include <linux/fdtable.h>
 #include <linux/console.h>
 #include <linux/timer.h>
 #include <linux/ctype.h>
 #include <linux/module.h>
 #include <linux/smp_lock.h>
 #include <linux/device.h>
-#include <linux/idr.h>
 #include <linux/wait.h>
 #include <linux/bitops.h>
 #include <linux/delay.h>
+#include <linux/seq_file.h>
 
-#include <asm/uaccess.h>
+#include <linux/uaccess.h>
 #include <asm/system.h>
 
 #include <linux/kbd_kern.h>
 #include <linux/selection.h>
 
 #include <linux/kmod.h>
+#include <linux/nsproxy.h>
 
 #undef TTY_DEBUG_HANGUP
 
@@ -125,7 +128,7 @@ EXPORT_SYMBOL(tty_std_termios);
 /* This list gets poked at by procfs and various bits of boot up code. This
    could do with some rationalisation such as pulling the tty proc function
    into this file */
-   
+
 LIST_HEAD(tty_drivers);                        /* linked list of tty drivers */
 
 /* Mutex to protect creating and releasing a tty. This is shared with
@@ -135,26 +138,29 @@ EXPORT_SYMBOL(tty_mutex);
 
 #ifdef CONFIG_UNIX98_PTYS
 extern struct tty_driver *ptm_driver;  /* Unix98 pty masters; for /dev/ptmx */
-extern int pty_limit;          /* Config limit on Unix98 ptys */
-static DEFINE_IDR(allocated_ptys);
-static DECLARE_MUTEX(allocated_ptys_lock);
 static int ptmx_open(struct inode *, struct file *);
 #endif
 
-extern void disable_early_printk(void);
-
 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 *);
+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 *);
-int tty_ioctl(struct inode * inode, struct file * file,
-             unsigned int cmd, unsigned long arg);
-static int tty_fasync(int fd, struct file * filp, int on);
-static void release_mem(struct tty_struct *tty, int idx);
+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,
+                               unsigned long arg);
+#else
+#define tty_compat_ioctl NULL
+#endif
+static int tty_fasync(int fd, struct file *filp, int on);
+static void release_tty(struct tty_struct *tty, int idx);
+static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
+static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
 
 /**
  *     alloc_tty_struct        -       allocate a tty object
@@ -170,8 +176,6 @@ static struct tty_struct *alloc_tty_struct(void)
        return kzalloc(sizeof(struct tty_struct), GFP_KERNEL);
 }
 
-static void tty_buffer_free_all(struct tty_struct *);
-
 /**
  *     free_tty_struct         -       free a disused tty
  *     @tty: tty struct to free
@@ -237,7 +241,7 @@ static int check_tty_count(struct tty_struct *tty, const char *routine)
 #ifdef CHECK_TTY_COUNT
        struct list_head *p;
        int count = 0;
-       
+
        file_list_lock();
        list_for_each(p, &tty->tty_files) {
                count++;
@@ -257,818 +261,6 @@ static int check_tty_count(struct tty_struct *tty, const char *routine)
        return 0;
 }
 
-/*
- * Tty buffer allocation management
- */
-
-/**
- *     tty_buffer_free_all             -       free buffers used by a tty
- *     @tty: tty to free from
- *
- *     Remove all the buffers pending on a tty whether queued with data
- *     or in the free ring. Must be called when the tty is no longer in use
- *
- *     Locking: none
- */
-
-static void tty_buffer_free_all(struct tty_struct *tty)
-{
-       struct tty_buffer *thead;
-       while((thead = tty->buf.head) != NULL) {
-               tty->buf.head = thead->next;
-               kfree(thead);
-       }
-       while((thead = tty->buf.free) != NULL) {
-               tty->buf.free = thead->next;
-               kfree(thead);
-       }
-       tty->buf.tail = NULL;
-       tty->buf.memory_used = 0;
-}
-
-/**
- *     tty_buffer_init         -       prepare a tty buffer structure
- *     @tty: tty to initialise
- *
- *     Set up the initial state of the buffer management for a tty device.
- *     Must be called before the other tty buffer functions are used.
- *
- *     Locking: none
- */
-
-static void tty_buffer_init(struct tty_struct *tty)
-{
-       spin_lock_init(&tty->buf.lock);
-       tty->buf.head = NULL;
-       tty->buf.tail = NULL;
-       tty->buf.free = NULL;
-       tty->buf.memory_used = 0;
-}
-
-/**
- *     tty_buffer_alloc        -       allocate a tty buffer
- *     @tty: tty device
- *     @size: desired size (characters)
- *
- *     Allocate a new tty buffer to hold the desired number of characters.
- *     Return NULL if out of memory or the allocation would exceed the
- *     per device queue
- *
- *     Locking: Caller must hold tty->buf.lock
- */
-
-static struct tty_buffer *tty_buffer_alloc(struct tty_struct *tty, size_t size)
-{
-       struct tty_buffer *p;
-
-       if (tty->buf.memory_used + size > 65536)
-               return NULL;
-       p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC);
-       if(p == NULL)
-               return NULL;
-       p->used = 0;
-       p->size = size;
-       p->next = NULL;
-       p->commit = 0;
-       p->read = 0;
-       p->char_buf_ptr = (char *)(p->data);
-       p->flag_buf_ptr = (unsigned char *)p->char_buf_ptr + size;
-       tty->buf.memory_used += size;
-       return p;
-}
-
-/**
- *     tty_buffer_free         -       free a tty buffer
- *     @tty: tty owning the buffer
- *     @b: the buffer to free
- *
- *     Free a tty buffer, or add it to the free list according to our
- *     internal strategy
- *
- *     Locking: Caller must hold tty->buf.lock
- */
-
-static void tty_buffer_free(struct tty_struct *tty, struct tty_buffer *b)
-{
-       /* Dumb strategy for now - should keep some stats */
-       tty->buf.memory_used -= b->size;
-       WARN_ON(tty->buf.memory_used < 0);
-
-       if(b->size >= 512)
-               kfree(b);
-       else {
-               b->next = tty->buf.free;
-               tty->buf.free = b;
-       }
-}
-
-/**
- *     tty_buffer_find         -       find a free tty buffer
- *     @tty: tty owning the buffer
- *     @size: characters wanted
- *
- *     Locate an existing suitable tty buffer or if we are lacking one then
- *     allocate a new one. We round our buffers off in 256 character chunks
- *     to get better allocation behaviour.
- *
- *     Locking: Caller must hold tty->buf.lock
- */
-
-static struct tty_buffer *tty_buffer_find(struct tty_struct *tty, size_t size)
-{
-       struct tty_buffer **tbh = &tty->buf.free;
-       while((*tbh) != NULL) {
-               struct tty_buffer *t = *tbh;
-               if(t->size >= size) {
-                       *tbh = t->next;
-                       t->next = NULL;
-                       t->used = 0;
-                       t->commit = 0;
-                       t->read = 0;
-                       tty->buf.memory_used += t->size;
-                       return t;
-               }
-               tbh = &((*tbh)->next);
-       }
-       /* Round the buffer size out */
-       size = (size + 0xFF) & ~ 0xFF;
-       return tty_buffer_alloc(tty, size);
-       /* Should possibly check if this fails for the largest buffer we
-          have queued and recycle that ? */
-}
-
-/**
- *     tty_buffer_request_room         -       grow tty buffer if needed
- *     @tty: tty structure
- *     @size: size desired
- *
- *     Make at least size bytes of linear space available for the tty
- *     buffer. If we fail return the size we managed to find.
- *
- *     Locking: Takes tty->buf.lock
- */
-int tty_buffer_request_room(struct tty_struct *tty, size_t size)
-{
-       struct tty_buffer *b, *n;
-       int left;
-       unsigned long flags;
-
-       spin_lock_irqsave(&tty->buf.lock, flags);
-
-       /* OPTIMISATION: We could keep a per tty "zero" sized buffer to
-          remove this conditional if its worth it. This would be invisible
-          to the callers */
-       if ((b = tty->buf.tail) != NULL)
-               left = b->size - b->used;
-       else
-               left = 0;
-
-       if (left < size) {
-               /* This is the slow path - looking for new buffers to use */
-               if ((n = tty_buffer_find(tty, size)) != NULL) {
-                       if (b != NULL) {
-                               b->next = n;
-                               b->commit = b->used;
-                       } else
-                               tty->buf.head = n;
-                       tty->buf.tail = n;
-               } else
-                       size = left;
-       }
-
-       spin_unlock_irqrestore(&tty->buf.lock, flags);
-       return size;
-}
-EXPORT_SYMBOL_GPL(tty_buffer_request_room);
-
-/**
- *     tty_insert_flip_string  -       Add characters to the tty buffer
- *     @tty: tty structure
- *     @chars: characters
- *     @size: size
- *
- *     Queue a series of bytes to the tty buffering. All the characters
- *     passed are marked as without error. Returns the number added.
- *
- *     Locking: Called functions may take tty->buf.lock
- */
-
-int tty_insert_flip_string(struct tty_struct *tty, const unsigned char *chars,
-                               size_t size)
-{
-       int copied = 0;
-       do {
-               int space = tty_buffer_request_room(tty, size - copied);
-               struct tty_buffer *tb = tty->buf.tail;
-               /* If there is no space then tb may be NULL */
-               if(unlikely(space == 0))
-                       break;
-               memcpy(tb->char_buf_ptr + tb->used, chars, space);
-               memset(tb->flag_buf_ptr + tb->used, TTY_NORMAL, space);
-               tb->used += space;
-               copied += space;
-               chars += space;
-               /* There is a small chance that we need to split the data over
-                  several buffers. If this is the case we must loop */
-       } while (unlikely(size > copied));
-       return copied;
-}
-EXPORT_SYMBOL(tty_insert_flip_string);
-
-/**
- *     tty_insert_flip_string_flags    -       Add characters to the tty buffer
- *     @tty: tty structure
- *     @chars: characters
- *     @flags: flag bytes
- *     @size: size
- *
- *     Queue a series of bytes to the tty buffering. For each character
- *     the flags array indicates the status of the character. Returns the
- *     number added.
- *
- *     Locking: Called functions may take tty->buf.lock
- */
-
-int tty_insert_flip_string_flags(struct tty_struct *tty,
-               const unsigned char *chars, const char *flags, size_t size)
-{
-       int copied = 0;
-       do {
-               int space = tty_buffer_request_room(tty, size - copied);
-               struct tty_buffer *tb = tty->buf.tail;
-               /* If there is no space then tb may be NULL */
-               if(unlikely(space == 0))
-                       break;
-               memcpy(tb->char_buf_ptr + tb->used, chars, space);
-               memcpy(tb->flag_buf_ptr + tb->used, flags, space);
-               tb->used += space;
-               copied += space;
-               chars += space;
-               flags += space;
-               /* There is a small chance that we need to split the data over
-                  several buffers. If this is the case we must loop */
-       } while (unlikely(size > copied));
-       return copied;
-}
-EXPORT_SYMBOL(tty_insert_flip_string_flags);
-
-/**
- *     tty_schedule_flip       -       push characters to ldisc
- *     @tty: tty to push from
- *
- *     Takes any pending buffers and transfers their ownership to the
- *     ldisc side of the queue. It then schedules those characters for
- *     processing by the line discipline.
- *
- *     Locking: Takes tty->buf.lock
- */
-
-void tty_schedule_flip(struct tty_struct *tty)
-{
-       unsigned long flags;
-       spin_lock_irqsave(&tty->buf.lock, flags);
-       if (tty->buf.tail != NULL)
-               tty->buf.tail->commit = tty->buf.tail->used;
-       spin_unlock_irqrestore(&tty->buf.lock, flags);
-       schedule_delayed_work(&tty->buf.work, 1);
-}
-EXPORT_SYMBOL(tty_schedule_flip);
-
-/**
- *     tty_prepare_flip_string         -       make room for characters
- *     @tty: tty
- *     @chars: return pointer for character write area
- *     @size: desired size
- *
- *     Prepare a block of space in the buffer for data. Returns the length
- *     available and buffer pointer to the space which is now allocated and
- *     accounted for as ready for normal characters. This is used for drivers
- *     that need their own block copy routines into the buffer. There is no
- *     guarantee the buffer is a DMA target!
- *
- *     Locking: May call functions taking tty->buf.lock
- */
-
-int tty_prepare_flip_string(struct tty_struct *tty, unsigned char **chars, size_t size)
-{
-       int space = tty_buffer_request_room(tty, size);
-       if (likely(space)) {
-               struct tty_buffer *tb = tty->buf.tail;
-               *chars = tb->char_buf_ptr + tb->used;
-               memset(tb->flag_buf_ptr + tb->used, TTY_NORMAL, space);
-               tb->used += space;
-       }
-       return space;
-}
-
-EXPORT_SYMBOL_GPL(tty_prepare_flip_string);
-
-/**
- *     tty_prepare_flip_string_flags   -       make room for characters
- *     @tty: tty
- *     @chars: return pointer for character write area
- *     @flags: return pointer for status flag write area
- *     @size: desired size
- *
- *     Prepare a block of space in the buffer for data. Returns the length
- *     available and buffer pointer to the space which is now allocated and
- *     accounted for as ready for characters. This is used for drivers
- *     that need their own block copy routines into the buffer. There is no
- *     guarantee the buffer is a DMA target!
- *
- *     Locking: May call functions taking tty->buf.lock
- */
-
-int tty_prepare_flip_string_flags(struct tty_struct *tty, unsigned char **chars, char **flags, size_t size)
-{
-       int space = tty_buffer_request_room(tty, size);
-       if (likely(space)) {
-               struct tty_buffer *tb = tty->buf.tail;
-               *chars = tb->char_buf_ptr + tb->used;
-               *flags = tb->flag_buf_ptr + tb->used;
-               tb->used += space;
-       }
-       return space;
-}
-
-EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags);
-
-
-
-/**
- *     tty_set_termios_ldisc           -       set ldisc field
- *     @tty: tty structure
- *     @num: line discipline number
- *
- *     This is probably overkill for real world processors but
- *     they are not on hot paths so a little discipline won't do 
- *     any harm.
- *
- *     Locking: takes termios_mutex
- */
-static void tty_set_termios_ldisc(struct tty_struct *tty, int num)
-{
-       mutex_lock(&tty->termios_mutex);
-       tty->termios->c_line = num;
-       mutex_unlock(&tty->termios_mutex);
-}
-
-/*
- *     This guards the refcounted line discipline lists. The lock
- *     must be taken with irqs off because there are hangup path
- *     callers who will do ldisc lookups and cannot sleep.
- */
-static DEFINE_SPINLOCK(tty_ldisc_lock);
-static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_wait);
-static struct tty_ldisc tty_ldiscs[NR_LDISCS]; /* line disc dispatch table */
-
-/**
- *     tty_register_ldisc      -       install a line discipline
- *     @disc: ldisc number
- *     @new_ldisc: pointer to the ldisc object
- *
- *     Installs a new line discipline into the kernel. The discipline
- *     is set up as unreferenced and then made available to the kernel
- *     from this point onwards.
- *
- *     Locking:
- *             takes tty_ldisc_lock to guard against ldisc races
- */
-
-int tty_register_ldisc(int disc, struct tty_ldisc *new_ldisc)
-{
-       unsigned long flags;
-       int ret = 0;
-       
-       if (disc < N_TTY || disc >= NR_LDISCS)
-               return -EINVAL;
-       
-       spin_lock_irqsave(&tty_ldisc_lock, flags);
-       tty_ldiscs[disc] = *new_ldisc;
-       tty_ldiscs[disc].num = disc;
-       tty_ldiscs[disc].flags |= LDISC_FLAG_DEFINED;
-       tty_ldiscs[disc].refcount = 0;
-       spin_unlock_irqrestore(&tty_ldisc_lock, flags);
-       
-       return ret;
-}
-EXPORT_SYMBOL(tty_register_ldisc);
-
-/**
- *     tty_unregister_ldisc    -       unload a line discipline
- *     @disc: ldisc number
- *     @new_ldisc: pointer to the ldisc object
- *
- *     Remove a line discipline from the kernel providing it is not
- *     currently in use.
- *
- *     Locking:
- *             takes tty_ldisc_lock to guard against ldisc races
- */
-
-int tty_unregister_ldisc(int disc)
-{
-       unsigned long flags;
-       int ret = 0;
-
-       if (disc < N_TTY || disc >= NR_LDISCS)
-               return -EINVAL;
-
-       spin_lock_irqsave(&tty_ldisc_lock, flags);
-       if (tty_ldiscs[disc].refcount)
-               ret = -EBUSY;
-       else
-               tty_ldiscs[disc].flags &= ~LDISC_FLAG_DEFINED;
-       spin_unlock_irqrestore(&tty_ldisc_lock, flags);
-
-       return ret;
-}
-EXPORT_SYMBOL(tty_unregister_ldisc);
-
-/**
- *     tty_ldisc_get           -       take a reference to an ldisc
- *     @disc: ldisc number
- *
- *     Takes a reference to a line discipline. Deals with refcounts and
- *     module locking counts. Returns NULL if the discipline is not available.
- *     Returns a pointer to the discipline and bumps the ref count if it is
- *     available
- *
- *     Locking:
- *             takes tty_ldisc_lock to guard against ldisc races
- */
-
-struct tty_ldisc *tty_ldisc_get(int disc)
-{
-       unsigned long flags;
-       struct tty_ldisc *ld;
-
-       if (disc < N_TTY || disc >= NR_LDISCS)
-               return NULL;
-       
-       spin_lock_irqsave(&tty_ldisc_lock, flags);
-
-       ld = &tty_ldiscs[disc];
-       /* Check the entry is defined */
-       if(ld->flags & LDISC_FLAG_DEFINED)
-       {
-               /* If the module is being unloaded we can't use it */
-               if (!try_module_get(ld->owner))
-                       ld = NULL;
-               else /* lock it */
-                       ld->refcount++;
-       }
-       else
-               ld = NULL;
-       spin_unlock_irqrestore(&tty_ldisc_lock, flags);
-       return ld;
-}
-
-EXPORT_SYMBOL_GPL(tty_ldisc_get);
-
-/**
- *     tty_ldisc_put           -       drop ldisc reference
- *     @disc: ldisc number
- *
- *     Drop a reference to a line discipline. Manage refcounts and
- *     module usage counts
- *
- *     Locking:
- *             takes tty_ldisc_lock to guard against ldisc races
- */
-
-void tty_ldisc_put(int disc)
-{
-       struct tty_ldisc *ld;
-       unsigned long flags;
-       
-       BUG_ON(disc < N_TTY || disc >= NR_LDISCS);
-               
-       spin_lock_irqsave(&tty_ldisc_lock, flags);
-       ld = &tty_ldiscs[disc];
-       BUG_ON(ld->refcount == 0);
-       ld->refcount--;
-       module_put(ld->owner);
-       spin_unlock_irqrestore(&tty_ldisc_lock, flags);
-}
-       
-EXPORT_SYMBOL_GPL(tty_ldisc_put);
-
-/**
- *     tty_ldisc_assign        -       set ldisc on a tty
- *     @tty: tty to assign
- *     @ld: line discipline
- *
- *     Install an instance of a line discipline into a tty structure. The
- *     ldisc must have a reference count above zero to ensure it remains/
- *     The tty instance refcount starts at zero.
- *
- *     Locking:
- *             Caller must hold references
- */
-
-static void tty_ldisc_assign(struct tty_struct *tty, struct tty_ldisc *ld)
-{
-       tty->ldisc = *ld;
-       tty->ldisc.refcount = 0;
-}
-
-/**
- *     tty_ldisc_try           -       internal helper
- *     @tty: the tty
- *
- *     Make a single attempt to grab and bump the refcount on
- *     the tty ldisc. Return 0 on failure or 1 on success. This is
- *     used to implement both the waiting and non waiting versions
- *     of tty_ldisc_ref
- *
- *     Locking: takes tty_ldisc_lock
- */
-
-static int tty_ldisc_try(struct tty_struct *tty)
-{
-       unsigned long flags;
-       struct tty_ldisc *ld;
-       int ret = 0;
-       
-       spin_lock_irqsave(&tty_ldisc_lock, flags);
-       ld = &tty->ldisc;
-       if(test_bit(TTY_LDISC, &tty->flags))
-       {
-               ld->refcount++;
-               ret = 1;
-       }
-       spin_unlock_irqrestore(&tty_ldisc_lock, flags);
-       return ret;
-}
-
-/**
- *     tty_ldisc_ref_wait      -       wait for the tty ldisc
- *     @tty: tty device
- *
- *     Dereference the line discipline for the terminal and take a 
- *     reference to it. If the line discipline is in flux then 
- *     wait patiently until it changes.
- *
- *     Note: Must not be called from an IRQ/timer context. The caller
- *     must also be careful not to hold other locks that will deadlock
- *     against a discipline change, such as an existing ldisc reference
- *     (which we check for)
- *
- *     Locking: call functions take tty_ldisc_lock
- */
-struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty)
-{
-       /* wait_event is a macro */
-       wait_event(tty_ldisc_wait, tty_ldisc_try(tty));
-       if(tty->ldisc.refcount == 0)
-               printk(KERN_ERR "tty_ldisc_ref_wait\n");
-       return &tty->ldisc;
-}
-
-EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait);
-
-/**
- *     tty_ldisc_ref           -       get the tty ldisc
- *     @tty: tty device
- *
- *     Dereference the line discipline for the terminal and take a 
- *     reference to it. If the line discipline is in flux then 
- *     return NULL. Can be called from IRQ and timer functions.
- *
- *     Locking: called functions take tty_ldisc_lock
- */
-struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty)
-{
-       if(tty_ldisc_try(tty))
-               return &tty->ldisc;
-       return NULL;
-}
-
-EXPORT_SYMBOL_GPL(tty_ldisc_ref);
-
-/**
- *     tty_ldisc_deref         -       free a tty ldisc reference
- *     @ld: reference to free up
- *
- *     Undoes the effect of tty_ldisc_ref or tty_ldisc_ref_wait. May
- *     be called in IRQ context.
- *
- *     Locking: takes tty_ldisc_lock
- */
-void tty_ldisc_deref(struct tty_ldisc *ld)
-{
-       unsigned long flags;
-
-       BUG_ON(ld == NULL);
-               
-       spin_lock_irqsave(&tty_ldisc_lock, flags);
-       if(ld->refcount == 0)
-               printk(KERN_ERR "tty_ldisc_deref: no references.\n");
-       else
-               ld->refcount--;
-       if(ld->refcount == 0)
-               wake_up(&tty_ldisc_wait);
-       spin_unlock_irqrestore(&tty_ldisc_lock, flags);
-}
-
-EXPORT_SYMBOL_GPL(tty_ldisc_deref);
-
-/**
- *     tty_ldisc_enable        -       allow ldisc use
- *     @tty: terminal to activate ldisc on
- *
- *     Set the TTY_LDISC flag when the line discipline can be called
- *     again. Do neccessary wakeups for existing sleepers.
- *
- *     Note: nobody should set this bit except via this function. Clearing
- *     directly is allowed.
- */
-
-static void tty_ldisc_enable(struct tty_struct *tty)
-{
-       set_bit(TTY_LDISC, &tty->flags);
-       wake_up(&tty_ldisc_wait);
-}
-       
-/**
- *     tty_set_ldisc           -       set line discipline
- *     @tty: the terminal to set
- *     @ldisc: the line discipline
- *
- *     Set the discipline of a tty line. Must be called from a process
- *     context.
- *
- *     Locking: takes tty_ldisc_lock.
- *              called functions take termios_mutex
- */
-static int tty_set_ldisc(struct tty_struct *tty, int ldisc)
-{
-       int retval = 0;
-       struct tty_ldisc o_ldisc;
-       char buf[64];
-       int work;
-       unsigned long flags;
-       struct tty_ldisc *ld;
-       struct tty_struct *o_tty;
-
-       if ((ldisc < N_TTY) || (ldisc >= NR_LDISCS))
-               return -EINVAL;
-
-restart:
-
-       ld = tty_ldisc_get(ldisc);
-       /* Eduardo Blanco <ejbs@cs.cs.com.uy> */
-       /* Cyrus Durgin <cider@speakeasy.org> */
-       if (ld == NULL) {
-               request_module("tty-ldisc-%d", ldisc);
-               ld = tty_ldisc_get(ldisc);
-       }
-       if (ld == NULL)
-               return -EINVAL;
-
-       /*
-        *      No more input please, we are switching. The new ldisc
-        *      will update this value in the ldisc open function
-        */
-
-       tty->receive_room = 0;
-
-       /*
-        *      Problem: What do we do if this blocks ?
-        */
-
-       tty_wait_until_sent(tty, 0);
-
-       if (tty->ldisc.num == ldisc) {
-               tty_ldisc_put(ldisc);
-               return 0;
-       }
-
-       o_ldisc = tty->ldisc;
-       o_tty = tty->link;
-
-       /*
-        *      Make sure we don't change while someone holds a
-        *      reference to the line discipline. The TTY_LDISC bit
-        *      prevents anyone taking a reference once it is clear.
-        *      We need the lock to avoid racing reference takers.
-        */
-
-       spin_lock_irqsave(&tty_ldisc_lock, flags);
-       if (tty->ldisc.refcount || (o_tty && o_tty->ldisc.refcount)) {
-               if(tty->ldisc.refcount) {
-                       /* Free the new ldisc we grabbed. Must drop the lock
-                          first. */
-                       spin_unlock_irqrestore(&tty_ldisc_lock, flags);
-                       tty_ldisc_put(ldisc);
-                       /*
-                        * There are several reasons we may be busy, including
-                        * random momentary I/O traffic. We must therefore
-                        * retry. We could distinguish between blocking ops
-                        * and retries if we made tty_ldisc_wait() smarter. That
-                        * is up for discussion.
-                        */
-                       if (wait_event_interruptible(tty_ldisc_wait, tty->ldisc.refcount == 0) < 0)
-                               return -ERESTARTSYS;
-                       goto restart;
-               }
-               if(o_tty && o_tty->ldisc.refcount) {
-                       spin_unlock_irqrestore(&tty_ldisc_lock, flags);
-                       tty_ldisc_put(ldisc);
-                       if (wait_event_interruptible(tty_ldisc_wait, o_tty->ldisc.refcount == 0) < 0)
-                               return -ERESTARTSYS;
-                       goto restart;
-               }
-       }
-
-       /* if the TTY_LDISC bit is set, then we are racing against another ldisc change */
-
-       if (!test_bit(TTY_LDISC, &tty->flags)) {
-               spin_unlock_irqrestore(&tty_ldisc_lock, flags);
-               tty_ldisc_put(ldisc);
-               ld = tty_ldisc_ref_wait(tty);
-               tty_ldisc_deref(ld);
-               goto restart;
-       }
-
-       clear_bit(TTY_LDISC, &tty->flags);
-       if (o_tty)
-               clear_bit(TTY_LDISC, &o_tty->flags);
-       spin_unlock_irqrestore(&tty_ldisc_lock, flags);
-
-       /*
-        *      From this point on we know nobody has an ldisc
-        *      usage reference, nor can they obtain one until
-        *      we say so later on.
-        */
-
-       work = cancel_delayed_work(&tty->buf.work);
-       /*
-        * Wait for ->hangup_work and ->buf.work handlers to terminate
-        */
-        
-       flush_scheduled_work();
-       /* Shutdown the current discipline. */
-       if (tty->ldisc.close)
-               (tty->ldisc.close)(tty);
-
-       /* Now set up the new line discipline. */
-       tty_ldisc_assign(tty, ld);
-       tty_set_termios_ldisc(tty, ldisc);
-       if (tty->ldisc.open)
-               retval = (tty->ldisc.open)(tty);
-       if (retval < 0) {
-               tty_ldisc_put(ldisc);
-               /* There is an outstanding reference here so this is safe */
-               tty_ldisc_assign(tty, tty_ldisc_get(o_ldisc.num));
-               tty_set_termios_ldisc(tty, tty->ldisc.num);
-               if (tty->ldisc.open && (tty->ldisc.open(tty) < 0)) {
-                       tty_ldisc_put(o_ldisc.num);
-                       /* This driver is always present */
-                       tty_ldisc_assign(tty, tty_ldisc_get(N_TTY));
-                       tty_set_termios_ldisc(tty, N_TTY);
-                       if (tty->ldisc.open) {
-                               int r = tty->ldisc.open(tty);
-
-                               if (r < 0)
-                                       panic("Couldn't open N_TTY ldisc for "
-                                             "%s --- error %d.",
-                                             tty_name(tty, buf), r);
-                       }
-               }
-       }
-       /* At this point we hold a reference to the new ldisc and a
-          a reference to the old ldisc. If we ended up flipping back
-          to the existing ldisc we have two references to it */
-       
-       if (tty->ldisc.num != o_ldisc.num && tty->driver->set_ldisc)
-               tty->driver->set_ldisc(tty);
-               
-       tty_ldisc_put(o_ldisc.num);
-       
-       /*
-        *      Allow ldisc referencing to occur as soon as the driver
-        *      ldisc callback completes.
-        */
-        
-       tty_ldisc_enable(tty);
-       if (o_tty)
-               tty_ldisc_enable(o_tty);
-       
-       /* Restart it in case no characters kick it off. Safe if
-          already running */
-       if (work)
-               schedule_delayed_work(&tty->buf.work, 1);
-       return retval;
-}
-
 /**
  *     get_tty_driver          -       find device of a tty
  *     @dev_t: device identifier
@@ -1094,6 +286,57 @@ static struct tty_driver *get_tty_driver(dev_t device, int *index)
        return NULL;
 }
 
+#ifdef CONFIG_CONSOLE_POLL
+
+/**
+ *     tty_find_polling_driver -       find device of a polled tty
+ *     @name: name string to match
+ *     @line: pointer to resulting tty line nr
+ *
+ *     This routine returns a tty driver structure, given a name
+ *     and the condition that the tty driver is capable of polled
+ *     operation.
+ */
+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;
+
+       for (str = name; *str; str++)
+               if ((*str >= '0' && *str <= '9') || *str == ',')
+                       break;
+       if (!*str)
+               return NULL;
+
+       len = str - name;
+       tty_line = simple_strtoul(str, &str, 10);
+
+       mutex_lock(&tty_mutex);
+       /* Search through the tty devices to look for a match */
+       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;
+
+               if (tty_line >= 0 && tty_line <= p->num && p->ops &&
+                   p->ops->poll_init && !p->ops->poll_init(p, tty_line, str)) {
+                       res = p;
+                       *line = tty_line;
+                       break;
+               }
+       }
+       mutex_unlock(&tty_mutex);
+
+       return res;
+}
+EXPORT_SYMBOL_GPL(tty_find_polling_driver);
+#endif
+
 /**
  *     tty_check_change        -       check for POSIX terminal changes
  *     @tty: tty to check
@@ -1102,49 +345,70 @@ static struct tty_driver *get_tty_driver(dev_t device, int *index)
  *     not in the foreground, send a SIGTTOU.  If the signal is blocked or
  *     ignored, go ahead and perform the operation.  (POSIX 7.2)
  *
- *     Locking: none
+ *     Locking: ctrl_lock
  */
 
-int tty_check_change(struct tty_struct * tty)
+int tty_check_change(struct tty_struct *tty)
 {
+       unsigned long flags;
+       int ret = 0;
+
        if (current->signal->tty != tty)
                return 0;
-       if (tty->pgrp <= 0) {
-               printk(KERN_WARNING "tty_check_change: tty->pgrp <= 0!\n");
-               return 0;
+
+       spin_lock_irqsave(&tty->ctrl_lock, flags);
+
+       if (!tty->pgrp) {
+               printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");
+               goto out_unlock;
        }
-       if (process_group(current) == tty->pgrp)
-               return 0;
+       if (task_pgrp(current) == tty->pgrp)
+               goto out_unlock;
+       spin_unlock_irqrestore(&tty->ctrl_lock, flags);
        if (is_ignored(SIGTTOU))
-               return 0;
-       if (is_orphaned_pgrp(process_group(current)))
-               return -EIO;
-       (void) kill_pg(process_group(current), SIGTTOU, 1);
-       return -ERESTARTSYS;
+               goto out;
+       if (is_current_pgrp_orphaned()) {
+               ret = -EIO;
+               goto out;
+       }
+       kill_pgrp(task_pgrp(current), SIGTTOU, 1);
+       set_thread_flag(TIF_SIGPENDING);
+       ret = -ERESTARTSYS;
+out:
+       return ret;
+out_unlock:
+       spin_unlock_irqrestore(&tty->ctrl_lock, flags);
+       return ret;
 }
 
 EXPORT_SYMBOL(tty_check_change);
 
-static ssize_t hung_up_tty_read(struct file * file, char __user * buf,
+static ssize_t hung_up_tty_read(struct file *file, char __user *buf,
                                size_t count, loff_t *ppos)
 {
        return 0;
 }
 
-static ssize_t hung_up_tty_write(struct file * file, const char __user * buf,
+static ssize_t hung_up_tty_write(struct file *file, const char __user *buf,
                                 size_t count, loff_t *ppos)
 {
        return -EIO;
 }
 
 /* No kernel lock held - none needed ;) */
-static unsigned int hung_up_tty_poll(struct file * filp, poll_table * wait)
+static unsigned int hung_up_tty_poll(struct file *filp, poll_table *wait)
 {
        return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM;
 }
 
-static int hung_up_tty_ioctl(struct inode * inode, struct file * file,
-                            unsigned int cmd, unsigned long arg)
+static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
+               unsigned long arg)
+{
+       return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
+}
+
+static long hung_up_tty_compat_ioctl(struct file *file,
+                                    unsigned int cmd, unsigned long arg)
 {
        return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
 }
@@ -1154,7 +418,8 @@ static const struct file_operations tty_fops = {
        .read           = tty_read,
        .write          = tty_write,
        .poll           = tty_poll,
-       .ioctl          = tty_ioctl,
+       .unlocked_ioctl = tty_ioctl,
+       .compat_ioctl   = tty_compat_ioctl,
        .open           = tty_open,
        .release        = tty_release,
        .fasync         = tty_fasync,
@@ -1166,7 +431,8 @@ static const struct file_operations ptmx_fops = {
        .read           = tty_read,
        .write          = tty_write,
        .poll           = tty_poll,
-       .ioctl          = tty_ioctl,
+       .unlocked_ioctl = tty_ioctl,
+       .compat_ioctl   = tty_compat_ioctl,
        .open           = ptmx_open,
        .release        = tty_release,
        .fasync         = tty_fasync,
@@ -1178,7 +444,8 @@ static const struct file_operations console_fops = {
        .read           = tty_read,
        .write          = redirected_tty_write,
        .poll           = tty_poll,
-       .ioctl          = tty_ioctl,
+       .unlocked_ioctl = tty_ioctl,
+       .compat_ioctl   = tty_compat_ioctl,
        .open           = tty_open,
        .release        = tty_release,
        .fasync         = tty_fasync,
@@ -1189,7 +456,8 @@ static const struct file_operations hung_up_tty_fops = {
        .read           = hung_up_tty_read,
        .write          = hung_up_tty_write,
        .poll           = hung_up_tty_poll,
-       .ioctl          = hung_up_tty_ioctl,
+       .unlocked_ioctl = hung_up_tty_ioctl,
+       .compat_ioctl   = hung_up_tty_compat_ioctl,
        .release        = tty_release,
 };
 
@@ -1204,16 +472,16 @@ static struct file *redirect;
  *     informs the line discipline if present that the driver is ready
  *     to receive more output data.
  */
+
 void tty_wakeup(struct tty_struct *tty)
 {
        struct tty_ldisc *ld;
-       
+
        if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
                ld = tty_ldisc_ref(tty);
-               if(ld) {
-                       if(ld->write_wakeup)
-                               ld->write_wakeup(tty);
+               if (ld) {
+                       if (ld->ops->write_wakeup)
+                               ld->ops->write_wakeup(tty);
                        tty_ldisc_deref(ld);
                }
        }
@@ -1229,15 +497,16 @@ EXPORT_SYMBOL_GPL(tty_wakeup);
  *     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->flush_buffer)
-                       ld->flush_buffer(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);
@@ -1257,7 +526,7 @@ static void tty_reset_termios(struct tty_struct *tty)
        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
@@ -1284,11 +553,13 @@ static void do_tty_hangup(struct work_struct *work)
 {
        struct tty_struct *tty =
                container_of(work, struct tty_struct, hangup_work);
-       struct file * cons_filp = NULL;
+       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;
@@ -1302,7 +573,7 @@ static void do_tty_hangup(struct work_struct *work)
                redirect = NULL;
        }
        spin_unlock(&redirect_lock);
-       
+
        check_tty_count(tty, "do_tty_hangup");
        file_list_lock();
        /* This breaks for file handles being sent over AF_UNIX sockets ? */
@@ -1316,84 +587,98 @@ 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. */
-
+       /*
+        * 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->flush_buffer)
-                       ld->flush_buffer(tty);
-               if (tty->driver->flush_buffer)
-                       tty->driver->flush_buffer(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->write_wakeup)
-                       ld->write_wakeup(tty);
-               if (ld->hangup)
-                       ld->hangup(tty);
+                   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 */
-          
+       /*
+        * 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 */
-       
+
        read_lock(&tasklist_lock);
-       if (tty->session > 0) {
-               do_each_task_pid(tty->session, PIDTYPE_SID, p) {
+       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;
                        }
                        __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
                        __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
-                       if (tty->pgrp > 0)
-                               p->signal->tty_old_pgrp = tty->pgrp;
+                       put_pid(p->signal->tty_old_pgrp);  /* A noop */
+                       spin_lock_irqsave(&tty->ctrl_lock, flags);
+                       if (tty->pgrp)
+                               p->signal->tty_old_pgrp = get_pid(tty->pgrp);
+                       spin_unlock_irqrestore(&tty->ctrl_lock, flags);
                        spin_unlock_irq(&p->sighand->siglock);
-               } while_each_task_pid(tty->session, PIDTYPE_SID, p);
+               } while_each_pid_task(tty->session, PIDTYPE_SID, p);
        }
        read_unlock(&tasklist_lock);
 
+       spin_lock_irqsave(&tty->ctrl_lock, flags);
        tty->flags = 0;
-       tty->session = 0;
-       tty->pgrp = -1;
+       put_pid(tty->session);
+       put_pid(tty->pgrp);
+       tty->session = NULL;
+       tty->pgrp = NULL;
        tty->ctrl_status = 0;
+       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
-        *      tty->count and state->count to go out of sync.
-        *      So we just call close() the right number of times.
+        * If one of the devices matches a console pointer, we
+        * cannot just call hangup() because that will cause
+        * tty->count and state->count to go out of sync.
+        * So we just call close() the right number of times.
         */
        if (cons_filp) {
-               if (tty->driver->close)
+               if (tty->ops->close)
                        for (n = 0; n < closecount; n++)
-                               tty->driver->close(tty, cons_filp);
-       } else if (tty->driver->hangup)
-               (tty->driver->hangup)(tty);
-               
-       /* We don't want to have driver/ldisc interactions beyond
-          the ones we did here. The driver layer expects no
-          calls after ->hangup() from the ldisc side. However we
-          can't yet guarantee all that */
-
+                               tty->ops->close(tty, cons_filp);
+       } else if (tty->ops->hangup)
+               (tty->ops->hangup)(tty);
+       /*
+        * We don't want to have driver/ldisc interactions beyond
+        * the ones we did here. The driver layer expects no
+        * calls after ->hangup() from the ldisc side. However we
+        * can't yet guarantee all that.
+        */
        set_bit(TTY_HUPPED, &tty->flags);
        if (ld) {
                tty_ldisc_enable(tty);
@@ -1412,11 +697,10 @@ static void do_tty_hangup(struct work_struct *work)
  *     schedule a hangup sequence to run after this event.
  */
 
-void tty_hangup(struct tty_struct * tty)
+void tty_hangup(struct tty_struct *tty)
 {
 #ifdef TTY_DEBUG_HANGUP
        char    buf[64];
-       
        printk(KERN_DEBUG "%s hangup...\n", tty_name(tty, buf));
 #endif
        schedule_work(&tty->hangup_work);
@@ -1430,10 +714,10 @@ EXPORT_SYMBOL(tty_hangup);
  *
  *     The user has asked via system call for the terminal to be hung up.
  *     We do this synchronously so that when the syscall returns the process
- *     is complete. That guarantee is neccessary for security reasons.
+ *     is complete. That guarantee is necessary for security reasons.
  */
 
-void tty_vhangup(struct tty_struct * tty)
+void tty_vhangup(struct tty_struct *tty)
 {
 #ifdef TTY_DEBUG_HANGUP
        char    buf[64];
@@ -1442,6 +726,7 @@ void tty_vhangup(struct tty_struct * tty)
 #endif
        do_tty_hangup(&tty->hangup_work);
 }
+
 EXPORT_SYMBOL(tty_vhangup);
 
 /**
@@ -1452,19 +737,19 @@ EXPORT_SYMBOL(tty_vhangup);
  *     loss
  */
 
-int tty_hung_up_p(struct file * filp)
+int tty_hung_up_p(struct file *filp)
 {
        return (filp->f_op == &hung_up_tty_fops);
 }
 
 EXPORT_SYMBOL(tty_hung_up_p);
 
-static void session_clear_tty(pid_t session)
+static void session_clear_tty(struct pid *session)
 {
        struct task_struct *p;
-       do_each_task_pid(session, PIDTYPE_SID, p) {
+       do_each_pid_task(session, PIDTYPE_SID, p) {
                proc_clear_tty(p);
-       } while_each_task_pid(session, PIDTYPE_SID, p);
+       } while_each_pid_task(session, PIDTYPE_SID, p);
 }
 
 /**
@@ -1494,46 +779,56 @@ static void session_clear_tty(pid_t session)
 void disassociate_ctty(int on_exit)
 {
        struct tty_struct *tty;
-       int tty_pgrp = -1;
-       int session;
+       struct pid *tty_pgrp = NULL;
 
-       lock_kernel();
 
        mutex_lock(&tty_mutex);
        tty = get_current_tty();
        if (tty) {
-               tty_pgrp = tty->pgrp;
+               tty_pgrp = get_pid(tty->pgrp);
                mutex_unlock(&tty_mutex);
-               /* XXX: here we race, there is nothing protecting tty */
+               lock_kernel();
                if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)
                        tty_vhangup(tty);
-       } else {
-               pid_t old_pgrp = current->signal->tty_old_pgrp;
+               unlock_kernel();
+               tty_kref_put(tty);
+       } else if (on_exit) {
+               struct pid *old_pgrp;
+               spin_lock_irq(&current->sighand->siglock);
+               old_pgrp = current->signal->tty_old_pgrp;
+               current->signal->tty_old_pgrp = NULL;
+               spin_unlock_irq(&current->sighand->siglock);
                if (old_pgrp) {
-                       kill_pg(old_pgrp, SIGHUP, on_exit);
-                       kill_pg(old_pgrp, SIGCONT, on_exit);
+                       kill_pgrp(old_pgrp, SIGHUP, on_exit);
+                       kill_pgrp(old_pgrp, SIGCONT, on_exit);
+                       put_pid(old_pgrp);
                }
                mutex_unlock(&tty_mutex);
-               unlock_kernel();        
                return;
        }
-       if (tty_pgrp > 0) {
-               kill_pg(tty_pgrp, SIGHUP, on_exit);
+       if (tty_pgrp) {
+               kill_pgrp(tty_pgrp, SIGHUP, on_exit);
                if (!on_exit)
-                       kill_pg(tty_pgrp, SIGCONT, on_exit);
+                       kill_pgrp(tty_pgrp, SIGCONT, on_exit);
+               put_pid(tty_pgrp);
        }
 
        spin_lock_irq(&current->sighand->siglock);
-       current->signal->tty_old_pgrp = 0;
-       session = process_session(current);
+       put_pid(current->signal->tty_old_pgrp);
+       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) {
-               tty->session = 0;
-               tty->pgrp = 0;
+               unsigned long flags;
+               spin_lock_irqsave(&tty->ctrl_lock, flags);
+               put_pid(tty->session);
+               put_pid(tty->pgrp);
+               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]"
@@ -1544,18 +839,31 @@ void disassociate_ctty(int on_exit)
 
        /* Now clear signal->tty under the lock */
        read_lock(&tasklist_lock);
-       session_clear_tty(session);
+       session_clear_tty(task_session(current));
        read_unlock(&tasklist_lock);
+}
+
+/**
+ *
+ *     no_tty  - Ensure the current process does not have a controlling tty
+ */
+void no_tty(void)
+{
+       struct task_struct *tsk = current;
+       lock_kernel();
+       if (tsk->signal->leader)
+               disassociate_ctty(0);
        unlock_kernel();
+       proc_clear_tty(tsk);
 }
 
 
 /**
- *     stop_tty        -       propogate flow control
+ *     stop_tty        -       propagate flow control
  *     @tty: tty to stop
  *
  *     Perform flow control to the driver. For PTY/TTY pairs we
- *     must also propogate the TIOCKPKT status. May be called
+ *     must also propagate the TIOCKPKT status. May be called
  *     on an already stopped device and will not re-call the driver
  *     method.
  *
@@ -1565,54 +873,62 @@ void disassociate_ctty(int on_exit)
  *     but not always.
  *
  *     Locking:
- *             Broken. Relies on BKL which is unsafe here.
+ *             Uses the tty control lock internally
  */
 
 void stop_tty(struct tty_struct *tty)
 {
-       if (tty->stopped)
+       unsigned long flags;
+       spin_lock_irqsave(&tty->ctrl_lock, flags);
+       if (tty->stopped) {
+               spin_unlock_irqrestore(&tty->ctrl_lock, flags);
                return;
+       }
        tty->stopped = 1;
        if (tty->link && tty->link->packet) {
                tty->ctrl_status &= ~TIOCPKT_START;
                tty->ctrl_status |= TIOCPKT_STOP;
                wake_up_interruptible(&tty->link->read_wait);
        }
-       if (tty->driver->stop)
-               (tty->driver->stop)(tty);
+       spin_unlock_irqrestore(&tty->ctrl_lock, flags);
+       if (tty->ops->stop)
+               (tty->ops->stop)(tty);
 }
 
 EXPORT_SYMBOL(stop_tty);
 
 /**
- *     start_tty       -       propogate flow control
+ *     start_tty       -       propagate flow control
  *     @tty: tty to start
  *
  *     Start a tty that has been stopped if at all possible. Perform
- *     any neccessary wakeups and propogate the TIOCPKT status. If this
+ *     any necessary wakeups and propagate the TIOCPKT status. If this
  *     is the tty was previous stopped and is being started then the
  *     driver start method is invoked and the line discipline woken.
  *
  *     Locking:
- *             Broken. Relies on BKL which is unsafe here.
+ *             ctrl_lock
  */
 
 void start_tty(struct tty_struct *tty)
 {
-       if (!tty->stopped || tty->flow_stopped)
+       unsigned long flags;
+       spin_lock_irqsave(&tty->ctrl_lock, flags);
+       if (!tty->stopped || tty->flow_stopped) {
+               spin_unlock_irqrestore(&tty->ctrl_lock, flags);
                return;
+       }
        tty->stopped = 0;
        if (tty->link && tty->link->packet) {
                tty->ctrl_status &= ~TIOCPKT_STOP;
                tty->ctrl_status |= TIOCPKT_START;
                wake_up_interruptible(&tty->link->read_wait);
        }
-       if (tty->driver->start)
-               (tty->driver->start)(tty);
-
+       spin_unlock_irqrestore(&tty->ctrl_lock, flags);
+       if (tty->ops->start)
+               (tty->ops->start)(tty);
        /* If we have a running line discipline it may need kicking */
        tty_wakeup(tty);
-       wake_up_interruptible(&tty->write_wait);
 }
 
 EXPORT_SYMBOL(start_tty);
@@ -1628,17 +944,15 @@ EXPORT_SYMBOL(start_tty);
  *     for hung up devices before calling the line discipline method.
  *
  *     Locking:
- *             Locks the line discipline internally while needed
- *             For historical reasons the line discipline read method is
- *     invoked under the BKL. This will go away in time so do not rely on it
- *     in new code. Multiple read calls may be outstanding in parallel.
+ *             Locks the line discipline internally while needed. Multiple
+ *     read calls may be outstanding in parallel.
  */
 
-static ssize_t tty_read(struct file * file, char __user * buf, size_t count, 
+static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
                        loff_t *ppos)
 {
        int i;
-       struct tty_struct * tty;
+       struct tty_struct *tty;
        struct inode *inode;
        struct tty_ldisc *ld;
 
@@ -1652,18 +966,33 @@ static ssize_t tty_read(struct file * file, char __user * buf, size_t count,
        /* We want to wait for the line discipline to sort out in this
           situation */
        ld = tty_ldisc_ref_wait(tty);
-       lock_kernel();
-       if (ld->read)
-               i = (ld->read)(tty,file,buf,count);
+       if (ld->ops->read)
+               i = (ld->ops->read)(tty, file, buf, count);
        else
                i = -EIO;
        tty_ldisc_deref(ld);
-       unlock_kernel();
        if (i > 0)
                inode->i_atime = current_fs_time(inode->i_sb);
        return i;
 }
 
+void tty_write_unlock(struct tty_struct *tty)
+{
+       mutex_unlock(&tty->atomic_write_lock);
+       wake_up_interruptible(&tty->write_wait);
+}
+
+int tty_write_lock(struct tty_struct *tty, int ndelay)
+{
+       if (!mutex_trylock(&tty->atomic_write_lock)) {
+               if (ndelay)
+                       return -EAGAIN;
+               if (mutex_lock_interruptible(&tty->atomic_write_lock))
+                       return -ERESTARTSYS;
+       }
+       return 0;
+}
+
 /*
  * Split writes up in sane blocksizes to avoid
  * denial-of-service type attacks
@@ -1675,13 +1004,12 @@ static inline ssize_t do_tty_write(
        const char __user *buf,
        size_t count)
 {
-       ssize_t ret = 0, written = 0;
+       ssize_t ret, written = 0;
        unsigned int chunk;
-       
-       /* FIXME: O_NDELAY ... */
-       if (mutex_lock_interruptible(&tty->atomic_write_lock)) {
-               return -ERESTARTSYS;
-       }
+
+       ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
+       if (ret < 0)
+               return ret;
 
        /*
         * We chunk up writes into a temporary buffer. This
@@ -1714,8 +1042,8 @@ static inline ssize_t do_tty_write(
 
                buf = kmalloc(chunk, GFP_KERNEL);
                if (!buf) {
-                       mutex_unlock(&tty->atomic_write_lock);
-                       return -ENOMEM;
+                       ret = -ENOMEM;
+                       goto out;
                }
                kfree(tty->write_buf);
                tty->write_cnt = chunk;
@@ -1730,9 +1058,7 @@ static inline ssize_t do_tty_write(
                ret = -EFAULT;
                if (copy_from_user(tty->write_buf, buf, size))
                        break;
-               lock_kernel();
                ret = write(tty, file, tty->write_buf, size);
-               unlock_kernel();
                if (ret <= 0)
                        break;
                written += ret;
@@ -1750,7 +1076,8 @@ static inline ssize_t do_tty_write(
                inode->i_mtime = current_fs_time(inode->i_sb);
                ret = written;
        }
-       mutex_unlock(&tty->atomic_write_lock);
+out:
+       tty_write_unlock(tty);
        return ret;
 }
 
@@ -1773,31 +1100,35 @@ static inline ssize_t do_tty_write(
  *     kernel lock for historical reasons. New code should not rely on this.
  */
 
-static ssize_t tty_write(struct file * file, const char __user * buf, size_t count,
-                        loff_t *ppos)
+static ssize_t tty_write(struct file *file, const char __user *buf,
+                                               size_t count, loff_t *ppos)
 {
-       struct tty_struct * tty;
+       struct tty_struct *tty;
        struct inode *inode = file->f_path.dentry->d_inode;
        ssize_t ret;
        struct tty_ldisc *ld;
-       
+
        tty = (struct tty_struct *)file->private_data;
        if (tty_paranoia_check(tty, inode, "tty_write"))
                return -EIO;
-       if (!tty || !tty->driver->write || (test_bit(TTY_IO_ERROR, &tty->flags)))
-               return -EIO;
-
-       ld = tty_ldisc_ref_wait(tty);           
-       if (!ld->write)
+       if (!tty || !tty->ops->write ||
+               (test_bit(TTY_IO_ERROR, &tty->flags)))
+                       return -EIO;
+       /* Short term debug to catch buggy drivers */
+       if (tty->ops->write_room == NULL)
+               printk(KERN_ERR "tty driver %s lacks a write_room method.\n",
+                       tty->driver->name);
+       ld = tty_ldisc_ref_wait(tty);
+       if (!ld->ops->write)
                ret = -EIO;
        else
-               ret = do_tty_write(ld->write, tty, file, buf, count);
+               ret = do_tty_write(ld->ops->write, tty, file, buf, count);
        tty_ldisc_deref(ld);
        return ret;
 }
 
-ssize_t redirected_tty_write(struct file * file, const char __user * buf, size_t count,
-                        loff_t *ppos)
+ssize_t redirected_tty_write(struct file *file, const char __user *buf,
+                                               size_t count, loff_t *ppos)
 {
        struct file *p = NULL;
 
@@ -1814,7 +1145,6 @@ ssize_t redirected_tty_write(struct file * file, const char __user * buf, size_t
                fput(p);
                return res;
        }
-
        return tty_write(file, buf, count, ppos);
 }
 
@@ -1836,8 +1166,8 @@ static void pty_line_name(struct tty_driver *driver, int index, char *p)
        int i = index + driver->name_base;
        /* ->name is initialized to "ttyp", but "tty" is expected */
        sprintf(p, "%s%c%x",
-                       driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
-                       ptychar[i >> 4 & 0xf], i & 0xf);
+               driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
+               ptychar[i >> 4 & 0xf], i & 0xf);
 }
 
 /**
@@ -1891,6 +1221,20 @@ static int init_dev(struct tty_driver *driver, int idx,
        /* 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 {
@@ -1902,7 +1246,7 @@ static int init_dev(struct tty_driver *driver, int idx,
         * First time open is complex, especially for PTY devices.
         * This code guarantees that either everything succeeds and the
         * TTY is ready for operation, or else the table slots are vacated
-        * and the allocated memory released.  (Except that the termios 
+        * and the allocated memory released.  (Except that the termios
         * and locked termios may be retained.)
         */
 
@@ -1916,10 +1260,11 @@ static int init_dev(struct tty_driver *driver, int idx,
        ltp = o_ltp = NULL;
 
        tty = alloc_tty_struct();
-       if(!tty)
+       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);
 
@@ -1932,27 +1277,31 @@ static int init_dev(struct tty_driver *driver, int idx,
        }
 
        if (!*tp_loc) {
-               tp = (struct ktermios *) kmalloc(sizeof(struct ktermios),
-                                               GFP_KERNEL);
+               tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
                if (!tp)
                        goto free_mem_out;
                *tp = driver->init_termios;
        }
 
        if (!*ltp_loc) {
-               ltp = (struct ktermios *) kmalloc(sizeof(struct ktermios),
-                                                GFP_KERNEL);
+               ltp = kzalloc(sizeof(struct ktermios), GFP_KERNEL);
                if (!ltp)
                        goto free_mem_out;
-               memset(ltp, 0, sizeof(struct ktermios));
        }
 
        if (driver->type == TTY_DRIVER_TYPE_PTY) {
                o_tty = alloc_tty_struct();
                if (!o_tty)
                        goto free_mem_out;
+               if (!try_module_get(driver->other->owner)) {
+                       /* This cannot in fact currently happen */
+                       free_tty_struct(o_tty);
+                       o_tty = NULL;
+                       goto free_mem_out;
+               }
                initialize_tty_struct(o_tty);
                o_tty->driver = driver->other;
+               o_tty->ops = driver->ops;
                o_tty->index = idx;
                tty_line_name(driver->other, idx, o_tty->name);
 
@@ -1965,27 +1314,23 @@ static int init_dev(struct tty_driver *driver, int idx,
                }
 
                if (!*o_tp_loc) {
-                       o_tp = (struct ktermios *)
-                               kmalloc(sizeof(struct ktermios), GFP_KERNEL);
+                       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 = (struct ktermios *)
-                               kmalloc(sizeof(struct ktermios), GFP_KERNEL);
+                       o_ltp = kzalloc(sizeof(struct ktermios), GFP_KERNEL);
                        if (!o_ltp)
                                goto free_mem_out;
-                       memset(o_ltp, 0, sizeof(struct ktermios));
                }
 
                /*
                 * Everything allocated ... set up the o_tty structure.
                 */
-               if (!(driver->other->flags & TTY_DRIVER_DEVPTS_MEM)) {
+               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)
@@ -2001,15 +1346,14 @@ static int init_dev(struct tty_driver *driver, int idx,
                o_tty->link = tty;
        }
 
-       /* 
+       /*
         * All structures have been allocated, so now we install them.
-        * Failures after this point use release_mem to clean up, so 
+        * 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)) {
+       if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM))
                driver->ttys[idx] = tty;
-       }
-       
+
        if (!*tp_loc)
                *tp_loc = tp;
        if (!*ltp_loc)
@@ -2022,28 +1366,17 @@ static int init_dev(struct tty_driver *driver, int idx,
        driver->refcount++;
        tty->count++;
 
-       /* 
+       /*
         * Structures all installed ... call the ldisc open routines.
-        * If we fail here just call release_mem to clean up.  No need
-        * to decrement the use counts, as release_mem doesn't care.
+        * If we fail here just call release_tty to clean up.  No need
+        * to decrement the use counts, as release_tty doesn't care.
         */
 
-       if (tty->ldisc.open) {
-               retval = (tty->ldisc.open)(tty);
-               if (retval)
-                       goto release_mem_out;
-       }
-       if (o_tty && o_tty->ldisc.open) {
-               retval = (o_tty->ldisc.open)(o_tty);
-               if (retval) {
-                       if (tty->ldisc.close)
-                               (tty->ldisc.close)(tty);
-                       goto release_mem_out;
-               }
-               tty_ldisc_enable(o_tty);
-       }
-       tty_ldisc_enable(tty);
-       goto success;
+       retval = tty_ldisc_setup(tty, o_tty);
+
+       if (retval)
+               goto release_mem_out;
+        goto success;
 
        /*
         * This fast open can be used if the tty is already open.
@@ -2059,7 +1392,7 @@ fast_track:
        if (driver->type == TTY_DRIVER_TYPE_PTY &&
            driver->subtype == PTY_TYPE_MASTER) {
                /*
-                * special case for PTY masters: only one open permitted, 
+                * special case for PTY masters: only one open permitted,
                 * and the slave side open count is incremented as well.
                 */
                if (tty->count) {
@@ -2072,11 +1405,11 @@ fast_track:
        tty->driver = driver; /* N.B. why do this every time?? */
 
        /* FIXME */
-       if(!test_bit(TTY_LDISC, &tty->flags))
+       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;
@@ -2084,8 +1417,10 @@ end_init:
        /* Release locally allocated memory ... nothing placed in slots */
 free_mem_out:
        kfree(o_tp);
-       if (o_tty)
+       if (o_tty) {
+               module_put(o_tty->driver->owner);
                free_tty_struct(o_tty);
+       }
        kfree(ltp);
        kfree(tp);
        free_tty_struct(tty);
@@ -2095,17 +1430,18 @@ fail_no_mem:
        retval = -ENOMEM;
        goto end_init;
 
-       /* call the tty release_mem routine to clean out this slot */
+       /* 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, "
                                 "clearing slot %d\n", idx);
-       release_mem(tty, idx);
+       release_tty(tty, idx);
        goto end_init;
 }
 
 /**
- *     release_mem             -       release tty structure memory
+ *     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
@@ -2115,40 +1451,20 @@ 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 ??
  */
-
-static void release_mem(struct tty_struct *tty, int idx)
+static void release_one_tty(struct kref *kref)
 {
-       struct tty_struct *o_tty;
-       struct ktermios *tp;
+       struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
+       struct tty_driver *driver = tty->driver;
        int devpts = tty->driver->flags & TTY_DRIVER_DEVPTS_MEM;
-
-       if ((o_tty = tty->link) != NULL) {
-               if (!devpts)
-                       o_tty->driver->ttys[idx] = NULL;
-               if (o_tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
-                       tp = o_tty->termios;
-                       if (!devpts)
-                               o_tty->driver->termios[idx] = NULL;
-                       kfree(tp);
-
-                       tp = o_tty->termios_locked;
-                       if (!devpts)
-                               o_tty->driver->termios_locked[idx] = NULL;
-                       kfree(tp);
-               }
-               o_tty->magic = 0;
-               o_tty->driver->refcount--;
-               file_list_lock();
-               list_del_init(&o_tty->tty_files);
-               file_list_unlock();
-               free_tty_struct(o_tty);
-       }
+       struct ktermios *tp;
+       int idx = tty->index;
 
        if (!devpts)
                tty->driver->ttys[idx] = NULL;
+
        if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
+               /* FIXME: Locking on ->termios array */
                tp = tty->termios;
                if (!devpts)
                        tty->driver->termios[idx] = NULL;
@@ -2160,13 +1476,55 @@ static void release_mem(struct tty_struct *tty, int idx)
                kfree(tp);
        }
 
-       tty->magic = 0;
-       tty->driver->refcount--;
-       file_list_lock();
-       list_del_init(&tty->tty_files);
-       file_list_unlock();
-       module_put(tty->driver->owner);
-       free_tty_struct(tty);
+
+       tty->magic = 0;
+       /* FIXME: locking on tty->driver->refcount */
+       tty->driver->refcount--;
+       module_put(driver->owner);
+
+       file_list_lock();
+       list_del_init(&tty->tty_files);
+       file_list_unlock();
+
+       free_tty_struct(tty);
+}
+
+/**
+ *     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, release_one_tty);
+}
+EXPORT_SYMBOL(tty_kref_put);
+
+/**
+ *     release_tty             -       release tty structure memory
+ *
+ *     Release both @tty and a possible linked partner (think pty pair),
+ *     and decrement the refcount of the backing module.
+ *
+ *     Locking:
+ *             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 ??
+ *
+ */
+static void release_tty(struct tty_struct *tty, int idx)
+{
+       /* This should always be true but check for the moment */
+       WARN_ON(tty->index != idx);
+
+       if (tty->link)
+               tty_kref_put(tty->link);
+       tty_kref_put(tty);
 }
 
 /*
@@ -2177,17 +1535,17 @@ static void release_mem(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)
+static void release_dev(struct file *filp)
 {
        struct tty_struct *tty, *o_tty;
        int     pty_master, tty_closing, o_tty_closing, do_sleep;
        int     devpts;
        int     idx;
        char    buf[64];
-       unsigned long flags;
-       
+
        tty = (struct tty_struct *)filp->private_data;
-       if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "release_dev"))
+       if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode,
+                                                       "release_dev"))
                return;
 
        check_tty_count(tty, "release_dev");
@@ -2247,7 +1605,7 @@ static void release_dev(struct file * filp)
                               idx, tty->name);
                        return;
                }
-               if (o_tty->termios_locked != 
+               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",
@@ -2260,8 +1618,8 @@ static void release_dev(struct file * filp)
                }
        }
 #endif
-       if (tty->driver->close)
-               tty->driver->close(tty, filp);
+       if (tty->ops->close)
+               tty->ops->close(tty, filp);
 
        /*
         * Sanity check: if tty->count is going to zero, there shouldn't be
@@ -2283,7 +1641,7 @@ static void release_dev(struct file * filp)
        while (1) {
                /* Guard against races with tty->count changes elsewhere and
                   opens on /dev/tty */
-                  
+
                mutex_lock(&tty_mutex);
                tty_closing = tty->count <= 1;
                o_tty_closing = o_tty &&
@@ -2317,11 +1675,11 @@ static void release_dev(struct file * filp)
                                    "active!\n", tty_name(tty, buf));
                mutex_unlock(&tty_mutex);
                schedule();
-       }       
+       }
 
        /*
-        * The closing flags are now consistent with the open counts on 
-        * both sides, and we've completed the last operation that could 
+        * The closing flags are now consistent with the open counts on
+        * both sides, and we've completed the last operation that could
         * block, so it's safe to proceed with closing.
         */
        if (pty_master) {
@@ -2337,7 +1695,7 @@ static void release_dev(struct file * filp)
                       tty->count, tty_name(tty, buf));
                tty->count = 0;
        }
-       
+
        /*
         * We've decremented tty->count, so we need to remove this file
         * descriptor off the tty->tty_files list; this serves two
@@ -2357,9 +1715,9 @@ static void release_dev(struct file * filp)
         * case of a pty we may have to wait around for the other side
         * to close, and TTY_CLOSING makes sure we can't be reopened.
         */
-       if(tty_closing)
+       if (tty_closing)
                set_bit(TTY_CLOSING, &tty->flags);
-       if(o_tty_closing)
+       if (o_tty_closing)
                set_bit(TTY_CLOSING, &o_tty->flags);
 
        /*
@@ -2380,76 +1738,23 @@ static void release_dev(struct file * filp)
        /* check whether both sides are closing ... */
        if (!tty_closing || (o_tty && !o_tty_closing))
                return;
-       
+
 #ifdef TTY_DEBUG_HANGUP
        printk(KERN_DEBUG "freeing tty structure...");
 #endif
        /*
-        * Prevent flush_to_ldisc() from rescheduling the work for later.  Then
-        * kill any delayed work. As this is the final close it does not
-        * race with the set_ldisc code path.
-        */
-       clear_bit(TTY_LDISC, &tty->flags);
-       cancel_delayed_work(&tty->buf.work);
-
-       /*
-        * Wait for ->hangup_work and ->buf.work handlers to terminate
-        */
-        
-       flush_scheduled_work();
-       
-       /*
-        * Wait for any short term users (we know they are just driver
-        * side waiters as the file is closing so user count on the file
-        * side is zero.
-        */
-       spin_lock_irqsave(&tty_ldisc_lock, flags);
-       while(tty->ldisc.refcount)
-       {
-               spin_unlock_irqrestore(&tty_ldisc_lock, flags);
-               wait_event(tty_ldisc_wait, tty->ldisc.refcount == 0);
-               spin_lock_irqsave(&tty_ldisc_lock, flags);
-       }
-       spin_unlock_irqrestore(&tty_ldisc_lock, flags);
-       /*
-        * Shutdown the current line discipline, and reset it to N_TTY.
-        * N.B. why reset ldisc when we're releasing the memory??
-        *
-        * FIXME: this MUST get fixed for the new reflocking
-        */
-       if (tty->ldisc.close)
-               (tty->ldisc.close)(tty);
-       tty_ldisc_put(tty->ldisc.num);
-       
-       /*
-        *      Switch the line discipline back
+        * Ask the line discipline code to release its structures
         */
-       tty_ldisc_assign(tty, tty_ldisc_get(N_TTY));
-       tty_set_termios_ldisc(tty,N_TTY); 
-       if (o_tty) {
-               /* FIXME: could o_tty be in setldisc here ? */
-               clear_bit(TTY_LDISC, &o_tty->flags);
-               if (o_tty->ldisc.close)
-                       (o_tty->ldisc.close)(o_tty);
-               tty_ldisc_put(o_tty->ldisc.num);
-               tty_ldisc_assign(o_tty, tty_ldisc_get(N_TTY));
-               tty_set_termios_ldisc(o_tty,N_TTY); 
-       }
+       tty_ldisc_release(tty, o_tty);
        /*
-        * The release_mem function takes care of the details of clearing
+        * The release_tty function takes care of the details of clearing
         * the slots and preserving the termios structure.
         */
-       release_mem(tty, idx);
+       release_tty(tty, idx);
 
-#ifdef CONFIG_UNIX98_PTYS
        /* Make this pty number available for reallocation */
-       if (devpts) {
-               down(&allocated_ptys_lock);
-               idr_remove(&allocated_ptys, idx);
-               up(&allocated_ptys_lock);
-       }
-#endif
-
+       if (devpts)
+               devpts_kill_index(idx);
 }
 
 /**
@@ -2473,7 +1778,7 @@ static void release_dev(struct file * filp)
  *              ->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;
        int noctty, retval;
@@ -2483,15 +1788,15 @@ static int tty_open(struct inode * inode, struct file * filp)
        unsigned short saved_flags = filp->f_flags;
 
        nonseekable_open(inode, filp);
-       
+
 retry_open:
        noctty = filp->f_flags & O_NOCTTY;
        index  = -1;
        retval = 0;
-       
+
        mutex_lock(&tty_mutex);
 
-       if (device == MKDEV(TTYAUX_MAJOR,0)) {
+       if (device == MKDEV(TTYAUX_MAJOR, 0)) {
                tty = get_current_tty();
                if (!tty) {
                        mutex_unlock(&tty_mutex);
@@ -2501,10 +1806,12 @@ retry_open:
                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)) {
+       if (device == MKDEV(TTY_MAJOR, 0)) {
                extern struct tty_driver *console_driver;
                driver = console_driver;
                index = fg_console;
@@ -2512,7 +1819,7 @@ retry_open:
                goto got_driver;
        }
 #endif
-       if (device == MKDEV(TTYAUX_MAJOR,1)) {
+       if (device == MKDEV(TTYAUX_MAJOR, 1)) {
                driver = console_device(&index);
                if (driver) {
                        /* Don't let /dev/console block */
@@ -2545,14 +1852,15 @@ got_driver:
        printk(KERN_DEBUG "opening %s...", tty->name);
 #endif
        if (!retval) {
-               if (tty->driver->open)
-                       retval = tty->driver->open(tty, filp);
+               if (tty->ops->open)
+                       retval = tty->ops->open(tty, filp);
                else
                        retval = -ENODEV;
        }
        filp->f_flags = saved_flags;
 
-       if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
+       if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) &&
+                                               !capable(CAP_SYS_ADMIN))
                retval = -EBUSY;
 
        if (retval) {
@@ -2579,13 +1887,26 @@ got_driver:
        if (!noctty &&
            current->signal->leader &&
            !current->signal->tty &&
-           tty->session == 0)
+           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
@@ -2595,43 +1916,27 @@ got_driver:
  *     Allocate a unix98 pty master device from the ptmx driver.
  *
  *     Locking: tty_mutex protects theinit_dev work. tty->count should
              protect the rest.
*             protect the rest.
  *             allocated_ptys_lock handles the list of free pty numbers
  */
 
-static int ptmx_open(struct inode * inode, struct file * filp)
+static int __ptmx_open(struct inode *inode, struct file *filp)
 {
        struct tty_struct *tty;
        int retval;
        int index;
-       int idr_ret;
 
        nonseekable_open(inode, filp);
 
        /* find a device that is not in use. */
-       down(&allocated_ptys_lock);
-       if (!idr_pre_get(&allocated_ptys, GFP_KERNEL)) {
-               up(&allocated_ptys_lock);
-               return -ENOMEM;
-       }
-       idr_ret = idr_get_new(&allocated_ptys, NULL, &index);
-       if (idr_ret < 0) {
-               up(&allocated_ptys_lock);
-               if (idr_ret == -EAGAIN)
-                       return -ENOMEM;
-               return -EIO;
-       }
-       if (index >= pty_limit) {
-               idr_remove(&allocated_ptys, index);
-               up(&allocated_ptys_lock);
-               return -EIO;
-       }
-       up(&allocated_ptys_lock);
+       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;
 
@@ -2639,23 +1944,31 @@ static int ptmx_open(struct inode * inode, struct file * filp)
        filp->private_data = tty;
        file_move(filp, &tty->tty_files);
 
-       retval = -ENOMEM;
-       if (devpts_pty_new(tty->link))
+       retval = devpts_pty_new(tty->link);
+       if (retval)
                goto out1;
 
-       check_tty_count(tty, "tty_open");
-       retval = ptm_driver->open(tty, filp);
+       check_tty_count(tty, "ptmx_open");
+       retval = ptm_driver->ops->open(tty, filp);
        if (!retval)
                return 0;
 out1:
        release_dev(filp);
        return retval;
 out:
-       down(&allocated_ptys_lock);
-       idr_remove(&allocated_ptys, index);
-       up(&allocated_ptys_lock);
+       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;
+}
 #endif
 
 /**
@@ -2670,7 +1983,7 @@ out:
  *             Takes bkl. See release_dev
  */
 
-static int tty_release(struct inode * inode, struct file * filp)
+static int tty_release(struct inode *inode, struct file *filp)
 {
        lock_kernel();
        release_dev(filp);
@@ -2690,47 +2003,63 @@ static int tty_release(struct inode * inode, struct file * filp)
  *     may be re-entered freely by other callers.
  */
 
-static unsigned int tty_poll(struct file * filp, poll_table * wait)
+static unsigned int tty_poll(struct file *filp, poll_table *wait)
 {
-       struct tty_struct * tty;
+       struct tty_struct *tty;
        struct tty_ldisc *ld;
        int ret = 0;
 
        tty = (struct tty_struct *)filp->private_data;
        if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_poll"))
                return 0;
-               
+
        ld = tty_ldisc_ref_wait(tty);
-       if (ld->poll)
-               ret = (ld->poll)(tty, filp, wait);
+       if (ld->ops->poll)
+               ret = (ld->ops->poll)(tty, filp, wait);
        tty_ldisc_deref(ld);
        return ret;
 }
 
-static int tty_fasync(int fd, struct file * filp, int on)
+static int tty_fasync(int fd, struct file *filp, int on)
 {
-       struct tty_struct * tty;
-       int retval;
+       struct tty_struct *tty;
+       unsigned long flags;
+       int retval = 0;
 
+       lock_kernel();
        tty = (struct tty_struct *)filp->private_data;
        if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_fasync"))
-               return 0;
-       
+               goto out;
+
        retval = fasync_helper(fd, filp, on, &tty->fasync);
        if (retval <= 0)
-               return retval;
+               goto out;
 
        if (on) {
+               enum pid_type type;
+               struct pid *pid;
                if (!waitqueue_active(&tty->read_wait))
                        tty->minimum_to_wake = 1;
-               retval = f_setown(filp, (-tty->pgrp) ? : current->pid, 0);
+               spin_lock_irqsave(&tty->ctrl_lock, flags);
+               if (tty->pgrp) {
+                       pid = tty->pgrp;
+                       type = PIDTYPE_PGID;
+               } else {
+                       pid = task_pid(current);
+                       type = PIDTYPE_PID;
+               }
+               spin_unlock_irqrestore(&tty->ctrl_lock, flags);
+               retval = __f_setown(filp, pid, type, 0);
                if (retval)
-                       return retval;
+                       goto out;
        } else {
                if (!tty->fasync && !waitqueue_active(&tty->read_wait))
                        tty->minimum_to_wake = N_TTY_BUF_SIZE;
        }
-       return 0;
+       retval = 0;
+out:
+       unlock_kernel();
+       return retval;
 }
 
 /**
@@ -2738,7 +2067,7 @@ static int tty_fasync(int fd, struct file * filp, int on)
  *     @tty: tty to fake input into
  *     @p: pointer to character
  *
- *     Fake input to a tty device. Does the neccessary locking and
+ *     Fake input to a tty device. Does the necessary locking and
  *     input management.
  *
  *     FIXME: does not honour flow control ??
@@ -2754,13 +2083,13 @@ static int tiocsti(struct tty_struct *tty, char __user *p)
 {
        char ch, mbz = 0;
        struct tty_ldisc *ld;
-       
+
        if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
                return -EPERM;
        if (get_user(ch, p))
                return -EFAULT;
        ld = tty_ldisc_ref_wait(tty);
-       ld->receive_buf(tty, &ch, &mbz, 1);
+       ld->ops->receive_buf(tty, &ch, &mbz, 1);
        tty_ldisc_deref(ld);
        return 0;
 }
@@ -2776,7 +2105,7 @@ static int tiocsti(struct tty_struct *tty, char __user *p)
  *             is consistent.
  */
 
-static int tiocgwinsz(struct tty_struct *tty, struct winsize __user * arg)
+static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
 {
        int err;
 
@@ -2788,6 +2117,49 @@ 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
+ *     peform a terminal resize correctly
+ */
+
+int tty_do_resize(struct tty_struct *tty, struct tty_struct *real_tty,
+                                       struct winsize *ws)
+{
+       struct pid *pgrp, *rpgrp;
+       unsigned long flags;
+
+       /* For a PTY we need to lock the tty side */
+       mutex_lock(&real_tty->termios_mutex);
+       if (!memcmp(ws, &real_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);
+       return 0;
+}
+
+/**
  *     tiocswinsz              -       implement window size set ioctl
  *     @tty; tty
  *     @arg: user buffer for result
@@ -2797,43 +2169,22 @@ static int tiocgwinsz(struct tty_struct *tty, struct winsize __user * arg)
  *     actually has driver level meaning and triggers a VC resize.
  *
  *     Locking:
- *             Called function use the console_sem is used to ensure we do
- *     not try and resize the console twice at once.
- *             The tty->termios_mutex is used to ensure we don't double
- *     resize and get confused. Lock order - tty->termios_mutex before
- *     console sem
+ *             Driver dependant. The default do_resize method takes the
+ *     tty termios mutex and ctrl_lock. The console takes its own lock
+ *     then calls into the default method.
  */
 
 static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty,
-       struct winsize __user * arg)
+       struct winsize __user *arg)
 {
        struct winsize tmp_ws;
-
        if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
                return -EFAULT;
 
-       mutex_lock(&tty->termios_mutex);
-       if (!memcmp(&tmp_ws, &tty->winsize, sizeof(*arg)))
-               goto done;
-
-#ifdef CONFIG_VT
-       if (tty->driver->type == TTY_DRIVER_TYPE_CONSOLE) {
-               if (vc_lock_resize(tty->driver_data, tmp_ws.ws_col,
-                                       tmp_ws.ws_row)) {
-                       mutex_unlock(&tty->termios_mutex);
-                       return -ENXIO;
-               }
-       }
-#endif
-       if (tty->pgrp > 0)
-               kill_pg(tty->pgrp, SIGWINCH, 1);
-       if ((real_tty->pgrp != tty->pgrp) && (real_tty->pgrp > 0))
-               kill_pg(real_tty->pgrp, SIGWINCH, 1);
-       tty->winsize = tmp_ws;
-       real_tty->winsize = tmp_ws;
-done:
-       mutex_unlock(&tty->termios_mutex);
-       return 0;
+       if (tty->ops->resize)
+               return tty->ops->resize(tty, real_tty, &tmp_ws);
+       else
+               return tty_do_resize(tty, real_tty, &tmp_ws);
 }
 
 /**
@@ -2889,10 +2240,13 @@ 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();
        if (nonblock)
                file->f_flags |= O_NONBLOCK;
        else
                file->f_flags &= ~O_NONBLOCK;
+       unlock_kernel();
        return 0;
 }
 
@@ -2913,8 +2267,7 @@ static int fionbio(struct file *file, int __user *p)
 static int tiocsctty(struct tty_struct *tty, int arg)
 {
        int ret = 0;
-       if (current->signal->leader &&
-                       (process_session(current) == tty->session))
+       if (current->signal->leader && (task_session(current) == tty->session))
                return ret;
 
        mutex_lock(&tty_mutex);
@@ -2927,12 +2280,12 @@ static int tiocsctty(struct tty_struct *tty, int arg)
                goto unlock;
        }
 
-       if (tty->session > 0) {
+       if (tty->session) {
                /*
                 * This tty is already the controlling
                 * tty for another session group!
                 */
-               if ((arg == 1) && capable(CAP_SYS_ADMIN)) {
+               if (arg == 1 && capable(CAP_SYS_ADMIN)) {
                        /*
                         * Steal it away
                         */
@@ -2951,6 +2304,27 @@ unlock:
 }
 
 /**
+ *     tty_get_pgrp    -       return a ref counted pgrp pid
+ *     @tty: tty to read
+ *
+ *     Returns a refcounted instance of the pid struct for the process
+ *     group controlling the tty.
+ */
+
+struct pid *tty_get_pgrp(struct tty_struct *tty)
+{
+       unsigned long flags;
+       struct pid *pgrp;
+
+       spin_lock_irqsave(&tty->ctrl_lock, flags);
+       pgrp = get_pid(tty->pgrp);
+       spin_unlock_irqrestore(&tty->ctrl_lock, flags);
+
+       return pgrp;
+}
+EXPORT_SYMBOL_GPL(tty_get_pgrp);
+
+/**
  *     tiocgpgrp               -       get process group
  *     @tty: tty passed by user
  *     @real_tty: tty side of the tty pased by the user if a pty else the tty
@@ -2964,13 +2338,18 @@ unlock:
 
 static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
 {
+       struct pid *pid;
+       int ret;
        /*
         * (tty == real_tty) is a cheap way of
         * testing if the tty is NOT a master pty.
         */
        if (tty == real_tty && current->signal->tty != real_tty)
                return -ENOTTY;
-       return put_user(real_tty->pgrp, p);
+       pid = tty_get_pgrp(real_tty);
+       ret =  put_user(pid_vnr(pid), p);
+       put_pid(pid);
+       return ret;
 }
 
 /**
@@ -2982,13 +2361,15 @@ static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t
  *     Set the process group of the tty to the session passed. Only
  *     permitted where the tty session is our session.
  *
- *     Locking: None
+ *     Locking: RCU, ctrl lock
  */
 
 static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
 {
-       pid_t pgrp;
+       struct pid *pgrp;
+       pid_t pgrp_nr;
        int retval = tty_check_change(real_tty);
+       unsigned long flags;
 
        if (retval == -EIO)
                return -ENOTTY;
@@ -2996,16 +2377,28 @@ static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t
                return retval;
        if (!current->signal->tty ||
            (current->signal->tty != real_tty) ||
-           (real_tty->session != process_session(current)))
+           (real_tty->session != task_session(current)))
                return -ENOTTY;
-       if (get_user(pgrp, p))
+       if (get_user(pgrp_nr, p))
                return -EFAULT;
-       if (pgrp < 0)
+       if (pgrp_nr < 0)
                return -EINVAL;
-       if (session_of_pgrp(pgrp) != process_session(current))
-               return -EPERM;
-       real_tty->pgrp = pgrp;
-       return 0;
+       rcu_read_lock();
+       pgrp = find_vpid(pgrp_nr);
+       retval = -ESRCH;
+       if (!pgrp)
+               goto out_unlock;
+       retval = -EPERM;
+       if (session_of_pgrp(pgrp) != task_session(current))
+               goto out_unlock;
+       retval = 0;
+       spin_lock_irqsave(&tty->ctrl_lock, flags);
+       put_pid(real_tty->pgrp);
+       real_tty->pgrp = get_pid(pgrp);
+       spin_unlock_irqrestore(&tty->ctrl_lock, flags);
+out_unlock:
+       rcu_read_unlock();
+       return retval;
 }
 
 /**
@@ -3028,9 +2421,9 @@ static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t _
        */
        if (tty == real_tty && current->signal->tty != real_tty)
                return -ENOTTY;
-       if (real_tty->session <= 0)
+       if (!real_tty->session)
                return -ENOTTY;
-       return put_user(real_tty->session, p);
+       return put_user(pid_vnr(real_tty->session), p);
 }
 
 /**
@@ -3046,10 +2439,16 @@ static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t _
 static int tiocsetd(struct tty_struct *tty, int __user *p)
 {
        int ldisc;
+       int ret;
 
        if (get_user(ldisc, p))
                return -EFAULT;
-       return tty_set_ldisc(tty, ldisc);
+
+       lock_kernel();
+       ret = tty_set_ldisc(tty, ldisc);
+       unlock_kernel();
+
+       return ret;
 }
 
 /**
@@ -3067,21 +2466,33 @@ static int tiocsetd(struct tty_struct *tty, int __user *p)
 
 static int send_break(struct tty_struct *tty, unsigned int duration)
 {
-       if (mutex_lock_interruptible(&tty->atomic_write_lock))
-               return -EINTR;
-       tty->driver->break_ctl(tty, -1);
-       if (!signal_pending(current)) {
-               msleep_interruptible(duration);
+       int retval;
+
+       if (tty->ops->break_ctl == NULL)
+               return 0;
+
+       if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
+               retval = tty->ops->break_ctl(tty, duration);
+       else {
+               /* Do the work ourselves */
+               if (tty_write_lock(tty, 0) < 0)
+                       return -EINTR;
+               retval = tty->ops->break_ctl(tty, -1);
+               if (retval)
+                       goto out;
+               if (!signal_pending(current))
+                       msleep_interruptible(duration);
+               retval = tty->ops->break_ctl(tty, 0);
+out:
+               tty_write_unlock(tty);
+               if (signal_pending(current))
+                       retval = -EINTR;
        }
-       tty->driver->break_ctl(tty, 0);
-       mutex_unlock(&tty->atomic_write_lock);
-       if (signal_pending(current))
-               return -EINTR;
-       return 0;
+       return retval;
 }
 
 /**
- *     tiocmget                -       get modem status
+ *     tty_tiocmget            -       get modem status
  *     @tty: tty device
  *     @file: user file pointer
  *     @p: pointer to result
@@ -3096,8 +2507,8 @@ static int tty_tiocmget(struct tty_struct *tty, struct file *file, int __user *p
 {
        int retval = -EINVAL;
 
-       if (tty->driver->tiocmget) {
-               retval = tty->driver->tiocmget(tty, file);
+       if (tty->ops->tiocmget) {
+               retval = tty->ops->tiocmget(tty, file);
 
                if (retval >= 0)
                        retval = put_user(retval, p);
@@ -3106,7 +2517,7 @@ static int tty_tiocmget(struct tty_struct *tty, struct file *file, int __user *p
 }
 
 /**
- *     tiocmset                -       set modem status
+ *     tty_tiocmset            -       set modem status
  *     @tty: tty device
  *     @file: user file pointer
  *     @cmd: command - clear bits, set bits or set all
@@ -3121,82 +2532,53 @@ static int tty_tiocmget(struct tty_struct *tty, struct file *file, int __user *p
 static int tty_tiocmset(struct tty_struct *tty, struct file *file, unsigned int cmd,
             unsigned __user *p)
 {
-       int retval = -EINVAL;
-
-       if (tty->driver->tiocmset) {
-               unsigned int set, clear, val;
-
-               retval = get_user(val, p);
-               if (retval)
-                       return retval;
-
-               set = clear = 0;
-               switch (cmd) {
-               case TIOCMBIS:
-                       set = val;
-                       break;
-               case TIOCMBIC:
-                       clear = val;
-                       break;
-               case TIOCMSET:
-                       set = val;
-                       clear = ~val;
-                       break;
-               }
+       int retval;
+       unsigned int set, clear, val;
 
-               set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
-               clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
+       if (tty->ops->tiocmset == NULL)
+               return -EINVAL;
 
-               retval = tty->driver->tiocmset(tty, file, set, clear);
+       retval = get_user(val, p);
+       if (retval)
+               return retval;
+       set = clear = 0;
+       switch (cmd) {
+       case TIOCMBIS:
+               set = val;
+               break;
+       case TIOCMBIC:
+               clear = val;
+               break;
+       case TIOCMSET:
+               set = val;
+               clear = ~val;
+               break;
        }
-       return retval;
+       set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
+       clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
+       return tty->ops->tiocmset(tty, file, set, clear);
 }
 
 /*
  * Split this up, as gcc can choke on it otherwise..
  */
-int tty_ioctl(struct inode * inode, struct file * file,
-             unsigned int cmd, unsigned long arg)
+long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
        struct tty_struct *tty, *real_tty;
        void __user *p = (void __user *)arg;
        int retval;
        struct tty_ldisc *ld;
-       
+       struct inode *inode = file->f_dentry->d_inode;
+
        tty = (struct tty_struct *)file->private_data;
        if (tty_paranoia_check(tty, inode, "tty_ioctl"))
                return -EINVAL;
 
-       /* CHECKME: is this safe as one end closes ? */
-
        real_tty = tty;
        if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
            tty->driver->subtype == PTY_TYPE_MASTER)
                real_tty = tty->link;
 
-       /*
-        * Break handling by driver
-        */
-       if (!tty->driver->break_ctl) {
-               switch(cmd) {
-               case TIOCSBRK:
-               case TIOCCBRK:
-                       if (tty->driver->ioctl)
-                               return tty->driver->ioctl(tty, file, cmd, arg);
-                       return -EINVAL;
-                       
-               /* These two ioctl's always return success; even if */
-               /* the driver doesn't support them. */
-               case TCSBRK:
-               case TCSBRKP:
-                       if (!tty->driver->ioctl)
-                               return 0;
-                       retval = tty->driver->ioctl(tty, file, cmd, arg);
-                       if (retval == -ENOIOCTLCMD)
-                               retval = 0;
-                       return retval;
-               }
-       }
 
        /*
         * Factor out some common prep work
@@ -3206,7 +2588,7 @@ int tty_ioctl(struct inode * inode, struct file * file,
        case TIOCSBRK:
        case TIOCCBRK:
        case TCSBRK:
-       case TCSBRKP:                   
+       case TCSBRKP:
                retval = tty_check_change(tty);
                if (retval)
                        return retval;
@@ -3218,85 +2600,90 @@ int tty_ioctl(struct inode * inode, struct file * file,
                break;
        }
 
+       /*
+        *      Now do the stuff.
+        */
        switch (cmd) {
-               case TIOCSTI:
-                       return tiocsti(tty, p);
-               case TIOCGWINSZ:
-                       return tiocgwinsz(tty, p);
-               case TIOCSWINSZ:
-                       return tiocswinsz(tty, real_tty, p);
-               case TIOCCONS:
-                       return real_tty!=tty ? -EINVAL : tioccons(file);
-               case FIONBIO:
-                       return fionbio(file, p);
-               case TIOCEXCL:
-                       set_bit(TTY_EXCLUSIVE, &tty->flags);
-                       return 0;
-               case TIOCNXCL:
-                       clear_bit(TTY_EXCLUSIVE, &tty->flags);
-                       return 0;
-               case TIOCNOTTY:
-                       if (current->signal->tty != tty)
-                               return -ENOTTY;
-                       if (current->signal->leader)
-                               disassociate_ctty(0);
-                       proc_clear_tty(current);
-                       return 0;
-               case TIOCSCTTY:
-                       return tiocsctty(tty, arg);
-               case TIOCGPGRP:
-                       return tiocgpgrp(tty, real_tty, p);
-               case TIOCSPGRP:
-                       return tiocspgrp(tty, real_tty, p);
-               case TIOCGSID:
-                       return tiocgsid(tty, real_tty, p);
-               case TIOCGETD:
-                       /* FIXME: check this is ok */
-                       return put_user(tty->ldisc.num, (int __user *)p);
-               case TIOCSETD:
-                       return tiocsetd(tty, p);
-#ifdef CONFIG_VT
-               case TIOCLINUX:
-                       return tioclinux(tty, arg);
-#endif
-               /*
-                * Break handling
+       case TIOCSTI:
+               return tiocsti(tty, p);
+       case TIOCGWINSZ:
+               return tiocgwinsz(real_tty, p);
+       case TIOCSWINSZ:
+               return tiocswinsz(tty, real_tty, p);
+       case TIOCCONS:
+               return real_tty != tty ? -EINVAL : tioccons(file);
+       case FIONBIO:
+               return fionbio(file, p);
+       case TIOCEXCL:
+               set_bit(TTY_EXCLUSIVE, &tty->flags);
+               return 0;
+       case TIOCNXCL:
+               clear_bit(TTY_EXCLUSIVE, &tty->flags);
+               return 0;
+       case TIOCNOTTY:
+               if (current->signal->tty != tty)
+                       return -ENOTTY;
+               no_tty();
+               return 0;
+       case TIOCSCTTY:
+               return tiocsctty(tty, arg);
+       case TIOCGPGRP:
+               return tiocgpgrp(tty, real_tty, p);
+       case TIOCSPGRP:
+               return tiocspgrp(tty, real_tty, p);
+       case TIOCGSID:
+               return tiocgsid(tty, real_tty, p);
+       case TIOCGETD:
+               return put_user(tty->ldisc.ops->num, (int __user *)p);
+       case TIOCSETD:
+               return tiocsetd(tty, p);
+       /*
+        * Break handling
+        */
+       case TIOCSBRK:  /* Turn break on, unconditionally */
+               if (tty->ops->break_ctl)
+                       return tty->ops->break_ctl(tty, -1);
+               return 0;
+       case TIOCCBRK:  /* Turn break off, unconditionally */
+               if (tty->ops->break_ctl)
+                       return tty->ops->break_ctl(tty, 0);
+               return 0;
+       case TCSBRK:   /* SVID version: non-zero arg --> no break */
+               /* non-zero arg means wait for all output data
+                * to be sent (performed above) but don't send break.
+                * This is used by the tcdrain() termios function.
                 */
-               case TIOCSBRK:  /* Turn break on, unconditionally */
-                       tty->driver->break_ctl(tty, -1);
-                       return 0;
-                       
-               case TIOCCBRK:  /* Turn break off, unconditionally */
-                       tty->driver->break_ctl(tty, 0);
-                       return 0;
-               case TCSBRK:   /* SVID version: non-zero arg --> no break */
-                       /* non-zero arg means wait for all output data
-                        * to be sent (performed above) but don't send break.
-                        * This is used by the tcdrain() termios function.
-                        */
-                       if (!arg)
-                               return send_break(tty, 250);
-                       return 0;
-               case TCSBRKP:   /* support for POSIX tcsendbreak() */   
-                       return send_break(tty, arg ? arg*100 : 250);
-
-               case TIOCMGET:
-                       return tty_tiocmget(tty, file, p);
-
-               case TIOCMSET:
-               case TIOCMBIC:
-               case TIOCMBIS:
-                       return tty_tiocmset(tty, file, cmd, p);
-       }
-       if (tty->driver->ioctl) {
-               retval = (tty->driver->ioctl)(tty, file, cmd, arg);
+               if (!arg)
+                       return send_break(tty, 250);
+               return 0;
+       case TCSBRKP:   /* support for POSIX tcsendbreak() */
+               return send_break(tty, arg ? arg*100 : 250);
+
+       case TIOCMGET:
+               return tty_tiocmget(tty, file, p);
+       case TIOCMSET:
+       case TIOCMBIC:
+       case TIOCMBIS:
+               return tty_tiocmset(tty, file, cmd, p);
+       case TCFLSH:
+               switch (arg) {
+               case TCIFLUSH:
+               case TCIOFLUSH:
+               /* flush tty buffer and allow ldisc to process ioctl */
+                       tty_buffer_flush(tty);
+                       break;
+               }
+               break;
+       }
+       if (tty->ops->ioctl) {
+               retval = (tty->ops->ioctl)(tty, file, cmd, arg);
                if (retval != -ENOIOCTLCMD)
                        return retval;
        }
        ld = tty_ldisc_ref_wait(tty);
        retval = -EINVAL;
-       if (ld->ioctl) {
-               retval = ld->ioctl(tty, file, cmd, arg);
+       if (ld->ops->ioctl) {
+               retval = ld->ops->ioctl(tty, file, cmd, arg);
                if (retval == -ENOIOCTLCMD)
                        retval = -EINVAL;
        }
@@ -3304,13 +2691,39 @@ int tty_ioctl(struct inode * inode, struct file * file,
        return retval;
 }
 
+#ifdef CONFIG_COMPAT
+static long tty_compat_ioctl(struct file *file, unsigned int cmd,
+                               unsigned long arg)
+{
+       struct inode *inode = file->f_dentry->d_inode;
+       struct tty_struct *tty = file->private_data;
+       struct tty_ldisc *ld;
+       int retval = -ENOIOCTLCMD;
+
+       if (tty_paranoia_check(tty, inode, "tty_ioctl"))
+               return -EINVAL;
+
+       if (tty->ops->compat_ioctl) {
+               retval = (tty->ops->compat_ioctl)(tty, file, cmd, arg);
+               if (retval != -ENOIOCTLCMD)
+                       return retval;
+       }
+
+       ld = tty_ldisc_ref_wait(tty);
+       if (ld->ops->compat_ioctl)
+               retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
+       tty_ldisc_deref(ld);
+
+       return retval;
+}
+#endif
 
 /*
  * This implements the "Secure Attention Key" ---  the idea is to
  * prevent trojan horses by killing all processes associated with this
  * tty when the user hits the "Secure Attention Key".  Required for
  * super-paranoid applications --- see the Orange Book for more details.
- * 
+ *
  * This code could be nicer; ideally it should send a HUP, wait a few
  * seconds, then send a INT, and then a KILL signal.  But you then
  * have to coordinate with the init process, since all processes associated
@@ -3330,36 +2743,35 @@ void __do_SAK(struct tty_struct *tty)
        tty_hangup(tty);
 #else
        struct task_struct *g, *p;
-       int session;
+       struct pid *session;
        int             i;
        struct file     *filp;
        struct fdtable *fdt;
-       
+
        if (!tty)
                return;
        session = tty->session;
-       
+
        tty_ldisc_flush(tty);
 
-       if (tty->driver->flush_buffer)
-               tty->driver->flush_buffer(tty);
-       
+       tty_driver_flush_buffer(tty);
+
        read_lock(&tasklist_lock);
        /* Kill the entire session */
-       do_each_task_pid(session, PIDTYPE_SID, p) {
+       do_each_pid_task(session, PIDTYPE_SID, p) {
                printk(KERN_NOTICE "SAK: killed process %d"
-                       " (%s): process_session(p)==tty->session\n",
-                       p->pid, p->comm);
+                       " (%s): task_session_nr(p)==tty->session\n",
+                       task_pid_nr(p), p->comm);
                send_sig(SIGKILL, p, 1);
-       } while_each_task_pid(session, PIDTYPE_SID, p);
+       } while_each_pid_task(session, PIDTYPE_SID, p);
        /* Now kill any processes that happen to have the
         * tty open.
         */
        do_each_thread(g, p) {
                if (p->signal->tty == tty) {
                        printk(KERN_NOTICE "SAK: killed process %d"
-                           " (%s): process_session(p)==tty->session\n",
-                           p->pid, p->comm);
+                           " (%s): task_session_nr(p)==tty->session\n",
+                           task_pid_nr(p), p->comm);
                        send_sig(SIGKILL, p, 1);
                        continue;
                }
@@ -3371,7 +2783,7 @@ void __do_SAK(struct tty_struct *tty)
                         */
                        spin_lock(&p->files->file_lock);
                        fdt = files_fdtable(p->files);
-                       for (i=0; i < fdt->max_fds; i++) {
+                       for (i = 0; i < fdt->max_fds; i++) {
                                filp = fcheck_files(p->files, i);
                                if (!filp)
                                        continue;
@@ -3379,7 +2791,7 @@ void __do_SAK(struct tty_struct *tty)
                                    filp->private_data == tty) {
                                        printk(KERN_NOTICE "SAK: killed process %d"
                                            " (%s): fd#%d opened to the tty\n",
-                                           p->pid, p->comm, i);
+                                           task_pid_nr(p), p->comm, i);
                                        force_sig(SIGKILL, p);
                                        break;
                                }
@@ -3409,103 +2821,12 @@ void do_SAK(struct tty_struct *tty)
 {
        if (!tty)
                return;
-       PREPARE_WORK(&tty->SAK_work, do_SAK_work);
        schedule_work(&tty->SAK_work);
 }
 
 EXPORT_SYMBOL(do_SAK);
 
 /**
- *     flush_to_ldisc
- *     @work: tty structure passed from work queue.
- *
- *     This routine is called out of the software interrupt to flush data
- *     from the buffer chain to the line discipline.
- *
- *     Locking: holds tty->buf.lock to guard buffer list. Drops the lock
- *     while invoking the line discipline receive_buf method. The
- *     receive_buf method is single threaded for each tty instance.
- */
-static void flush_to_ldisc(struct work_struct *work)
-{
-       struct tty_struct *tty =
-               container_of(work, struct tty_struct, buf.work.work);
-       unsigned long   flags;
-       struct tty_ldisc *disc;
-       struct tty_buffer *tbuf, *head;
-       char *char_buf;
-       unsigned char *flag_buf;
-
-       disc = tty_ldisc_ref(tty);
-       if (disc == NULL)       /*  !TTY_LDISC */
-               return;
-
-       spin_lock_irqsave(&tty->buf.lock, flags);
-       head = tty->buf.head;
-       if (head != NULL) {
-               tty->buf.head = NULL;
-               for (;;) {
-                       int count = head->commit - head->read;
-                       if (!count) {
-                               if (head->next == NULL)
-                                       break;
-                               tbuf = head;
-                               head = head->next;
-                               tty_buffer_free(tty, tbuf);
-                               continue;
-                       }
-                       if (!tty->receive_room) {
-                               schedule_delayed_work(&tty->buf.work, 1);
-                               break;
-                       }
-                       if (count > tty->receive_room)
-                               count = tty->receive_room;
-                       char_buf = head->char_buf_ptr + head->read;
-                       flag_buf = head->flag_buf_ptr + head->read;
-                       head->read += count;
-                       spin_unlock_irqrestore(&tty->buf.lock, flags);
-                       disc->receive_buf(tty, char_buf, flag_buf, count);
-                       spin_lock_irqsave(&tty->buf.lock, flags);
-               }
-               tty->buf.head = head;
-       }
-       spin_unlock_irqrestore(&tty->buf.lock, flags);
-
-       tty_ldisc_deref(disc);
-}
-
-/**
- *     tty_flip_buffer_push    -       terminal
- *     @tty: tty to push
- *
- *     Queue a push of the terminal flip buffers to the line discipline. This
- *     function must not be called from IRQ context if tty->low_latency is set.
- *
- *     In the event of the queue being busy for flipping the work will be
- *     held off and retried later.
- *
- *     Locking: tty buffer lock. Driver locks in low latency mode.
- */
-
-void tty_flip_buffer_push(struct tty_struct *tty)
-{
-       unsigned long flags;
-       spin_lock_irqsave(&tty->buf.lock, flags);
-       if (tty->buf.tail != NULL)
-               tty->buf.tail->commit = tty->buf.tail->used;
-       spin_unlock_irqrestore(&tty->buf.lock, flags);
-
-       if (tty->low_latency)
-               flush_to_ldisc(&tty->buf.work.work);
-       else
-               schedule_delayed_work(&tty->buf.work, 1);
-}
-
-EXPORT_SYMBOL(tty_flip_buffer_push);
-
-
-/**
  *     initialize_tty_struct
  *     @tty: tty to initialize
  *
@@ -3518,14 +2839,14 @@ EXPORT_SYMBOL(tty_flip_buffer_push);
 static void initialize_tty_struct(struct tty_struct *tty)
 {
        memset(tty, 0, sizeof(struct tty_struct));
+       kref_init(&tty->kref);
        tty->magic = TTY_MAGIC;
-       tty_ldisc_assign(tty, tty_ldisc_get(N_TTY));
-       tty->pgrp = -1;
+       tty_ldisc_init(tty);
+       tty->session = NULL;
+       tty->pgrp = NULL;
        tty->overrun_time = jiffies;
        tty->buf.head = tty->buf.tail = NULL;
        tty_buffer_init(tty);
-       INIT_DELAYED_WORK(&tty->buf.work, flush_to_ldisc);
-       init_MUTEX(&tty->buf.pty_sem);
        mutex_init(&tty->termios_mutex);
        init_waitqueue_head(&tty->write_wait);
        init_waitqueue_head(&tty->read_wait);
@@ -3533,19 +2854,32 @@ static void initialize_tty_struct(struct tty_struct *tty)
        mutex_init(&tty->atomic_read_lock);
        mutex_init(&tty->atomic_write_lock);
        spin_lock_init(&tty->read_lock);
+       spin_lock_init(&tty->ctrl_lock);
        INIT_LIST_HEAD(&tty->tty_files);
-       INIT_WORK(&tty->SAK_work, NULL);
+       INIT_WORK(&tty->SAK_work, do_SAK_work);
 }
 
-/*
- * The default put_char routine if the driver did not define one.
+/**
+ *     tty_put_char    -       write one character to a tty
+ *     @tty: tty
+ *     @ch: character
+ *
+ *     Write one byte to the tty using the provided put_char method
+ *     if present. Returns the number of characters successfully output.
+ *
+ *     Note: the specific put_char operation in the driver layer may go
+ *     away soon. Don't call it directly, use this method
  */
 
-static void tty_default_put_char(struct tty_struct *tty, unsigned char ch)
+int tty_put_char(struct tty_struct *tty, unsigned char ch)
 {
-       tty->driver->write(tty, &ch, 1);
+       if (tty->ops->put_char)
+               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;
 
 /**
@@ -3584,7 +2918,7 @@ struct device *tty_register_device(struct tty_driver *driver, unsigned index,
        else
                tty_line_name(driver, index, name);
 
-       return device_create(tty_class, device, dev, name);
+       return device_create_drvdata(tty_class, device, dev, NULL, name);
 }
 
 /**
@@ -3600,7 +2934,8 @@ struct device *tty_register_device(struct tty_driver *driver, unsigned index,
 
 void tty_unregister_device(struct tty_driver *driver, unsigned index)
 {
-       device_destroy(tty_class, MKDEV(driver->major, driver->minor_start) + index);
+       device_destroy(tty_class,
+               MKDEV(driver->major, driver->minor_start) + index);
 }
 
 EXPORT_SYMBOL(tty_register_device);
@@ -3610,9 +2945,8 @@ struct tty_driver *alloc_tty_driver(int lines)
 {
        struct tty_driver *driver;
 
-       driver = kmalloc(sizeof(struct tty_driver), GFP_KERNEL);
+       driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
        if (driver) {
-               memset(driver, 0, sizeof(struct tty_driver));
                driver->magic = TTY_DRIVER_MAGIC;
                driver->num = lines;
                /* later we'll move allocation of tables here */
@@ -3628,31 +2962,8 @@ void put_tty_driver(struct tty_driver *driver)
 void tty_set_operations(struct tty_driver *driver,
                        const struct tty_operations *op)
 {
-       driver->open = op->open;
-       driver->close = op->close;
-       driver->write = op->write;
-       driver->put_char = op->put_char;
-       driver->flush_chars = op->flush_chars;
-       driver->write_room = op->write_room;
-       driver->chars_in_buffer = op->chars_in_buffer;
-       driver->ioctl = op->ioctl;
-       driver->set_termios = op->set_termios;
-       driver->throttle = op->throttle;
-       driver->unthrottle = op->unthrottle;
-       driver->stop = op->stop;
-       driver->start = op->start;
-       driver->hangup = op->hangup;
-       driver->break_ctl = op->break_ctl;
-       driver->flush_buffer = op->flush_buffer;
-       driver->set_ldisc = op->set_ldisc;
-       driver->wait_until_sent = op->wait_until_sent;
-       driver->send_xchar = op->send_xchar;
-       driver->read_proc = op->read_proc;
-       driver->write_proc = op->write_proc;
-       driver->tiocmget = op->tiocmget;
-       driver->tiocmset = op->tiocmset;
-}
-
+       driver->ops = op;
+};
 
 EXPORT_SYMBOL(alloc_tty_driver);
 EXPORT_SYMBOL(put_tty_driver);
@@ -3664,31 +2975,29 @@ EXPORT_SYMBOL(tty_set_operations);
 int tty_register_driver(struct tty_driver *driver)
 {
        int error;
-        int i;
+       int i;
        dev_t dev;
        void **p = NULL;
 
        if (driver->flags & TTY_DRIVER_INSTALLED)
                return 0;
 
-       if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
-               p = kmalloc(driver->num * 3 * sizeof(void *), GFP_KERNEL);
+       if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM) && driver->num) {
+               p = kzalloc(driver->num * 3 * sizeof(void *), GFP_KERNEL);
                if (!p)
                        return -ENOMEM;
-               memset(p, 0, driver->num * 3 * sizeof(void *));
        }
 
        if (!driver->major) {
-               error = alloc_chrdev_region(&dev, driver->minor_start, driver->num,
-                                               (char*)driver->name);
+               error = alloc_chrdev_region(&dev, driver->minor_start,
+                                               driver->num, driver->name);
                if (!error) {
                        driver->major = MAJOR(dev);
                        driver->minor_start = MINOR(dev);
                }
        } else {
                dev = MKDEV(driver->major, driver->minor_start);
-               error = register_chrdev_region(dev, driver->num,
-                                               (char*)driver->name);
+               error = register_chrdev_region(dev, driver->num, driver->name);
        }
        if (error < 0) {
                kfree(p);
@@ -3698,7 +3007,8 @@ 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);
+               driver->termios_locked = (struct ktermios **)
+                                                       (p + driver->num * 2);
        } else {
                driver->ttys = NULL;
                driver->termios = NULL;
@@ -3716,13 +3026,12 @@ int tty_register_driver(struct tty_driver *driver)
                return error;
        }
 
-       if (!driver->put_char)
-               driver->put_char = tty_default_put_char;
-       
+       mutex_lock(&tty_mutex);
        list_add(&driver->tty_drivers, &tty_drivers);
-       
-       if ( !(driver->flags & TTY_DRIVER_DYNAMIC_DEV) ) {
-               for(i = 0; i < driver->num; i++)
+       mutex_unlock(&tty_mutex);
+
+       if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
+               for (i = 0; i < driver->num; i++)
                    tty_register_device(driver, i, NULL);
        }
        proc_tty_register_driver(driver);
@@ -3745,8 +3054,9 @@ int tty_unregister_driver(struct tty_driver *driver)
 
        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
@@ -3785,23 +3095,38 @@ EXPORT_SYMBOL(tty_devnum);
 
 void proc_clear_tty(struct task_struct *p)
 {
+       struct tty_struct *tty;
        spin_lock_irq(&p->sighand->siglock);
+       tty = p->signal->tty;
        p->signal->tty = NULL;
        spin_unlock_irq(&p->sighand->siglock);
+       tty_kref_put(tty);
 }
-EXPORT_SYMBOL(proc_clear_tty);
 
-void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
+/* Called under the sighand lock */
+
+static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
 {
        if (tty) {
-               tty->session = process_session(tsk);
-               tty->pgrp = process_group(tsk);
+               unsigned long flags;
+               /* We should not have a session or pgrp to put here but.... */
+               spin_lock_irqsave(&tty->ctrl_lock, flags);
+               put_pid(tty->session);
+               put_pid(tty->pgrp);
+               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);
+               }
        }
-       tsk->signal->tty = tty;
-       tsk->signal->tty_old_pgrp = 0;
+       put_pid(tsk->signal->tty_old_pgrp);
+       tsk->signal->tty = tty_kref_get(tty);
+       tsk->signal->tty_old_pgrp = NULL;
 }
 
-void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
+static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
 {
        spin_lock_irq(&tsk->sighand->siglock);
        __proc_set_tty(tsk, tty);
@@ -3812,7 +3137,7 @@ struct tty_struct *get_current_tty(void)
 {
        struct tty_struct *tty;
        WARN_ON_ONCE(!mutex_is_locked(&tty_mutex));
-       tty = current->signal->tty;
+       tty = tty_kref_get(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
@@ -3834,15 +3159,12 @@ void __init console_init(void)
        initcall_t *call;
 
        /* Setup the default TTY line discipline. */
-       (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY);
+       tty_ldisc_begin();
 
        /*
-        * set up the console device so that later boot sequences can 
+        * set up the console device so that later boot sequences can
         * inform about problems etc..
         */
-#ifdef CONFIG_EARLY_PRINTK
-       disable_early_printk();
-#endif
        call = __con_initcall_start;
        while (call < __con_initcall_end) {
                (*call)();
@@ -3850,10 +3172,6 @@ void __init console_init(void)
        }
 }
 
-#ifdef CONFIG_VT
-extern int vty_init(void);
-#endif
-
 static int __init tty_class_init(void)
 {
        tty_class = class_create(THIS_MODULE, "tty");
@@ -3884,20 +3202,22 @@ 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(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), "tty");
+       device_create_drvdata(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(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 1), "console");
+       device_create_drvdata(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(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), "ptmx");
+       device_create_drvdata(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
 #endif
 
 #ifdef CONFIG_VT
@@ -3905,7 +3225,7 @@ static int __init tty_init(void)
        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(tty_class, NULL, MKDEV(TTY_MAJOR, 0), "tty0");
+       device_create_drvdata(tty_class, NULL, MKDEV(TTY_MAJOR, 0), NULL, "tty0");
 
        vty_init();
 #endif