blob: 9c867cf6de6456293314eb1675e697c87a9f64d2 [file] [log] [blame]
/*
* linux/drivers/char/tty_io.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*/
/*
* 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles
* or rs-channels. It also implements echoing, cooked mode etc.
*
* Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.
*
* Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the
* tty_struct and tty_queue structures. Previously there was an array
* of 256 tty_struct's which was statically allocated, and the
* tty_queue structures were allocated at boot time. Both are now
* dynamically allocated only when the tty is open.
*
* 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
*
* Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
* which can be dynamically activated and de-activated by the line
* discipline handling modules (like SLIP).
*
* NOTE: pay no attention to the line discipline code (yet); its
* interface is still subject to change in this version...
* -- TYT, 1/31/92
*
* Added functionality to the OPOST tty handling. No delays, but all
* other bits should be there.
* -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993.
*
* Rewrote canonical mode and added more termios flags.
* -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94
*
* Reorganized FASYNC support so mouse code can share it.
* -- ctm@ardi.com, 9Sep95
*
* New TIOCLINUX variants added.
* -- mj@k332.feld.cvut.cz, 19-Nov-95
*
* Restrict vt switching via ioctl()
* -- grif@cs.ucr.edu, 5-Dec-95
*
* Move console and virtual terminal code to more appropriate files,
* implement CONFIG_VT and generalize console device interface.
* -- Marko Kohtala <Marko.Kohtala@hut.fi>, March 97
*
* Rewrote init_dev and release_dev to eliminate races.
* -- Bill Hawes <whawes@star.net>, June 97
*
* Added devfs support.
* -- C. Scott Ananian <cananian@alumni.princeton.edu>, 13-Jan-1998
*
* Added support for a Unix98-style ptmx device.
* -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
*
* Reduced memory usage for older ARM systems
* -- 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
*/
#include <linux/types.h>
#include <linux/major.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/fcntl.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/devpts_fs.h>
#include <linux/file.h>
#include <linux/console.h>
#include <linux/timer.h>
#include <linux/ctype.h>
#include <linux/kd.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/poll.h>
#include <linux/proc_fs.h>
#include <linux/init.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 <asm/uaccess.h>
#include <asm/system.h>
#include <linux/kbd_kern.h>
#include <linux/vt_kern.h>
#include <linux/selection.h>
#include <linux/kmod.h>
#undef TTY_DEBUG_HANGUP
#define TTY_PARANOIA_CHECK 1
#define CHECK_TTY_COUNT 1
struct ktermios tty_std_termios = { /* for the benefit of tty drivers */
.c_iflag = ICRNL | IXON,
.c_oflag = OPOST | ONLCR,
.c_cflag = B38400 | CS8 | CREAD | HUPCL,
.c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
ECHOCTL | ECHOKE | IEXTEN,
.c_cc = INIT_C_CC,
.c_ispeed = 38400,
.c_ospeed = 38400
};
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
vt.c for deeply disgusting hack reasons */
DEFINE_MUTEX(tty_mutex);
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
static void initialize_tty_struct(struct tty_struct *tty);
static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
ssize_t redirected_tty_write(struct file *, const char __user *, size_t, loff_t *);
static unsigned int tty_poll(struct file *, poll_table *);
static int tty_open(struct inode *, struct file *);
static int tty_release(struct inode *, struct file *);
int tty_ioctl(struct inode * inode, 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
*
* Return a new empty tty structure. The data fields have not
* been initialized in any way but has been zeroed
*
* Locking: none
*/
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
*
* Free the write buffers, tty queue and tty memory itself.
*
* Locking: none. Must be called after tty is definitely unused
*/
static inline void free_tty_struct(struct tty_struct *tty)
{
kfree(tty->write_buf);
tty_buffer_free_all(tty);
kfree(tty);
}
#define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base)
/**
* tty_name - return tty naming
* @tty: tty structure
* @buf: buffer for output
*
* Convert a tty structure into a name. The name reflects the kernel
* naming policy and if udev is in use may not reflect user space
*
* Locking: none
*/
char *tty_name(struct tty_struct *tty, char *buf)
{
if (!tty) /* Hmm. NULL pointer. That's fun. */
strcpy(buf, "NULL tty");
else
strcpy(buf, tty->name);
return buf;
}
EXPORT_SYMBOL(tty_name);
int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
const char *routine)
{
#ifdef TTY_PARANOIA_CHECK
if (!tty) {
printk(KERN_WARNING
"null TTY for (%d:%d) in %s\n",
imajor(inode), iminor(inode), routine);
return 1;
}
if (tty->magic != TTY_MAGIC) {
printk(KERN_WARNING
"bad magic number for tty struct (%d:%d) in %s\n",
imajor(inode), iminor(inode), routine);
return 1;
}
#endif
return 0;
}
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++;
}
file_list_unlock();
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_SLAVE &&
tty->link && tty->link->count)
count++;
if (tty->count != count) {
printk(KERN_WARNING "Warning: dev (%s) tty->count(%d) "
"!= #fd's(%d) in %s\n",
tty->name, tty->count, count, routine);
return count;
}
#endif
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_flush - flush full tty buffers
* @tty: tty to flush
*
* flush all the buffers containing receive data. Caller must
* hold the buffer lock and must have ensured no parallel flush to
* ldisc is running.
*
* Locking: Caller must hold tty->buf.lock
*/
static void __tty_buffer_flush(struct tty_struct *tty)
{
struct tty_buffer *thead;
while((thead = tty->buf.head) != NULL) {
tty->buf.head = thead->next;
tty_buffer_free(tty, thead);
}
tty->buf.tail = NULL;
}
/**
* tty_buffer_flush - flush full tty buffers
* @tty: tty to flush
*
* flush all the buffers containing receive data. If the buffer is
* being processed by flush_to_ldisc then we defer the processing
* to that function
*
* Locking: none
*/
static void tty_buffer_flush(struct tty_struct *tty)
{
unsigned long flags;
spin_lock_irqsave(&tty->buf.lock, flags);
/* If the data is being pushed to the tty layer then we can't
process it here. Instead set a flag and the flush_to_ldisc
path will process the flush request before it exits */
if (test_bit(TTY_FLUSHING, &tty->flags)) {
set_bit(TTY_FLUSHPENDING, &tty->flags);
spin_unlock_irqrestore(&tty->buf.lock, flags);
wait_event(tty->read_wait,
test_bit(TTY_FLUSHPENDING, &tty->flags) == 0);
return;
} else
__tty_buffer_flush(tty);
spin_unlock_irqrestore(&tty->buf.lock, flags);
}
/**
* 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;
/*
* 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;
}
/*
* No more input please, we are switching. The new ldisc
* will update this value in the ldisc open function
*/
tty->receive_room = 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
* @index: returns the index of the tty
*
* This routine returns a tty driver structure, given a device number
* and also passes back the index number.
*
* Locking: caller must hold tty_mutex
*/
static struct tty_driver *get_tty_driver(dev_t device, int *index)
{
struct tty_driver *p;
list_for_each_entry(p, &tty_drivers, tty_drivers) {
dev_t base = MKDEV(p->major, p->minor_start);
if (device < base || device >= base + p->num)
continue;
*index = device - base;
return p;
}
return NULL;
}
/**
* tty_check_change - check for POSIX terminal changes
* @tty: tty to check
*
* If we try to write to, or set the state of, a terminal and we're
* 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
*/
int tty_check_change(struct tty_struct * tty)
{
if (current->signal->tty != tty)
return 0;
if (!tty->pgrp) {
printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");
return 0;
}
if (task_pgrp(current) == tty->pgrp)
return 0;
if (is_ignored(SIGTTOU))
return 0;
if (is_current_pgrp_orphaned())
return -EIO;
kill_pgrp(task_pgrp(current), SIGTTOU, 1);
set_thread_flag(TIF_SIGPENDING);
return -ERESTARTSYS;
}
EXPORT_SYMBOL(tty_check_change);
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,
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)
{
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)
{
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;
}
static const struct file_operations tty_fops = {
.llseek = no_llseek,
.read = tty_read,
.write = tty_write,
.poll = tty_poll,
.ioctl = tty_ioctl,
.compat_ioctl = tty_compat_ioctl,
.open = tty_open,
.release = tty_release,
.fasync = tty_fasync,
};
#ifdef CONFIG_UNIX98_PTYS
static const struct file_operations ptmx_fops = {
.llseek = no_llseek,
.read = tty_read,
.write = tty_write,
.poll = tty_poll,
.ioctl = tty_ioctl,
.compat_ioctl = tty_compat_ioctl,
.open = ptmx_open,
.release = tty_release,
.fasync = tty_fasync,
};
#endif
static const struct file_operations console_fops = {
.llseek = no_llseek,
.read = tty_read,
.write = redirected_tty_write,
.poll = tty_poll,
.ioctl = tty_ioctl,
.compat_ioctl = tty_compat_ioctl,
.open = tty_open,
.release = tty_release,
.fasync = tty_fasync,
};
static const struct file_operations hung_up_tty_fops = {
.llseek = no_llseek,
.read = hung_up_tty_read,
.write = hung_up_tty_write,
.poll = hung_up_tty_poll,
.ioctl = hung_up_tty_ioctl,
.compat_ioctl = hung_up_tty_compat_ioctl,
.release = tty_release,
};
static DEFINE_SPINLOCK(redirect_lock);
static struct file *redirect;
/**
* tty_wakeup - request more data
* @tty: terminal
*
* Internal and external helper for wakeups of tty. This function
* 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);
tty_ldisc_deref(ld);
}
}
wake_up_interruptible(&tty->write_wait);
}
EXPORT_SYMBOL_GPL(tty_wakeup);
/**
* tty_ldisc_flush - flush line discipline queue
* @tty: tty
*
* Flush the line discipline queue (if any) for this tty. If there
* is no line discipline active this is a no-op.
*/
void tty_ldisc_flush(struct tty_struct *tty)
{
struct tty_ldisc *ld = tty_ldisc_ref(tty);
if(ld) {
if(ld->flush_buffer)
ld->flush_buffer(tty);
tty_ldisc_deref(ld);
}
tty_buffer_flush(tty);
}
EXPORT_SYMBOL_GPL(tty_ldisc_flush);
/**
* tty_reset_termios - reset terminal state
* @tty: tty to reset
*
* Restore a terminal to the driver default state
*/
static void tty_reset_termios(struct tty_struct *tty)
{
mutex_lock(&tty->termios_mutex);
*tty->termios = tty->driver->init_termios;
tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
mutex_unlock(&tty->termios_mutex);
}
/**
* do_tty_hangup - actual handler for hangup events
* @work: tty device
*
* This can be called by the "eventd" kernel thread. That is process
* synchronous but doesn't hold any locks, so we need to make sure we
* have the appropriate locks for what we're doing.
*
* The hangup event clears any pending redirections onto the hung up
* device. It ensures future writes will error and it does the needed
* line discipline hangup and signal delivery. The tty object itself
* remains intact.
*
* Locking:
* BKL
* redirect lock for undoing redirection
* file list lock for manipulating list of ttys
* tty_ldisc_lock from called functions
* termios_mutex resetting termios data
* tasklist_lock to walk task list for hangup event
* ->siglock to protect ->signal/->sighand
*/
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 *filp, *f = NULL;
struct task_struct *p;
struct tty_ldisc *ld;
int closecount = 0, n;
if (!tty)
return;
/* inuse_filps is protected by the single kernel lock */
lock_kernel();
spin_lock(&redirect_lock);
if (redirect && redirect->private_data == tty) {
f = redirect;
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 ? */
list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) {
if (filp->f_op->write == redirected_tty_write)
cons_filp = filp;
if (filp->f_op->write != tty_write)
continue;
closecount++;
tty_fasync(-1, filp, 0); /* can't block */
filp->f_op = &hung_up_tty_fops;
}
file_list_unlock();
/* FIXME! What are the locking issues here? This may me overdoing things..
* this question is especially important now that we've removed the irqlock. */
ld = tty_ldisc_ref(tty);
if(ld != NULL) /* We may have no line discipline at this point */
{
if (ld->flush_buffer)
ld->flush_buffer(tty);
if (tty->driver->flush_buffer)
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);
}
/* 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) {
do_each_pid_task(tty->session, PIDTYPE_SID, p) {
spin_lock_irq(&p->sighand->siglock);
if (p->signal->tty == tty)
p->signal->tty = NULL;
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);
put_pid(p->signal->tty_old_pgrp); /* A noop */
if (tty->pgrp)
p->signal->tty_old_pgrp = get_pid(tty->pgrp);
spin_unlock_irq(&p->sighand->siglock);
} while_each_pid_task(tty->session, PIDTYPE_SID, p);
}
read_unlock(&tasklist_lock);
tty->flags = 0;
put_pid(tty->session);
put_pid(tty->pgrp);
tty->session = NULL;
tty->pgrp = NULL;
tty->ctrl_status = 0;
/*
* 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)
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 */
set_bit(TTY_HUPPED, &tty->flags);
if (ld) {
tty_ldisc_enable(tty);
tty_ldisc_deref(ld);
}
unlock_kernel();
if (f)
fput(f);
}
/**
* tty_hangup - trigger a hangup event
* @tty: tty to hangup
*
* A carrier loss (virtual or otherwise) has occurred on this like
* schedule a hangup sequence to run after this event.
*/
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);
}
EXPORT_SYMBOL(tty_hangup);
/**
* tty_vhangup - process vhangup
* @tty: tty to 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.
*/
void tty_vhangup(struct tty_struct * tty)
{
#ifdef TTY_DEBUG_HANGUP
char buf[64];
printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf));
#endif
do_tty_hangup(&tty->hangup_work);
}
EXPORT_SYMBOL(tty_vhangup);
/**
* tty_hung_up_p - was tty hung up
* @filp: file pointer of tty
*
* Return true if the tty has been subject to a vhangup or a carrier
* loss
*/
int tty_hung_up_p(struct file * filp)
{
return (filp->f_op == &hung_up_tty_fops);
}
EXPORT_SYMBOL(tty_hung_up_p);
/**
* is_tty - checker whether file is a TTY
*/
int is_tty(struct file *filp)
{
return filp->f_op->read == tty_read
|| filp->f_op->read == hung_up_tty_read;
}
static void session_clear_tty(struct pid *session)
{
struct task_struct *p;
do_each_pid_task(session, PIDTYPE_SID, p) {
proc_clear_tty(p);
} while_each_pid_task(session, PIDTYPE_SID, p);
}
/**
* disassociate_ctty - disconnect controlling tty
* @on_exit: true if exiting so need to "hang up" the session
*
* This function is typically called only by the session leader, when
* it wants to disassociate itself from its controlling tty.
*
* It performs the following functions:
* (1) Sends a SIGHUP and SIGCONT to the foreground process group
* (2) Clears the tty from being controlling the session
* (3) Clears the controlling tty for all processes in the
* session group.
*
* The argument on_exit is set to 1 if called when a process is
* exiting; it is 0 if called by the ioctl TIOCNOTTY.
*
* Locking:
* BKL is taken for hysterical raisins
* tty_mutex is taken to protect tty
* ->siglock is taken to protect ->signal/->sighand
* tasklist_lock is taken to walk process list for sessions
* ->siglock is taken to protect ->signal/->sighand
*/
void disassociate_ctty(int on_exit)
{
struct tty_struct *tty;
struct pid *tty_pgrp = NULL;
lock_kernel();
mutex_lock(&tty_mutex);
tty = get_current_tty();
if (tty) {
tty_pgrp = get_pid(tty->pgrp);
mutex_unlock(&tty_mutex);
/* XXX: here we race, there is nothing protecting tty */
if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)
tty_vhangup(tty);
} 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_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) {
kill_pgrp(tty_pgrp, SIGHUP, on_exit);
if (!on_exit)
kill_pgrp(tty_pgrp, SIGCONT, on_exit);
put_pid(tty_pgrp);
}
spin_lock_irq(&current->sighand->siglock);
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) {
put_pid(tty->session);
put_pid(tty->pgrp);
tty->session = NULL;
tty->pgrp = NULL;
} else {
#ifdef TTY_DEBUG_HANGUP
printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
" = NULL", tty);
#endif
}
mutex_unlock(&tty_mutex);
/* Now clear signal->tty under the lock */
read_lock(&tasklist_lock);
session_clear_tty(task_session(current));
read_unlock(&tasklist_lock);
unlock_kernel();
}
/**
*
* no_tty - Ensure the current process does not have a controlling tty
*/
void no_tty(void)
{
struct task_struct *tsk = current;
if (tsk->signal->leader)
disassociate_ctty(0);
proc_clear_tty(tsk);
}
/**
* stop_tty - propagate flow control
* @tty: tty to stop
*
* Perform flow control to the driver. For PTY/TTY pairs we
* must also propagate the TIOCKPKT status. May be called
* on an already stopped device and will not re-call the driver
* method.
*
* This functionality is used by both the line disciplines for
* halting incoming flow and by the driver. It may therefore be
* called from any context, may be under the tty atomic_write_lock
* but not always.
*
* Locking:
* Broken. Relies on BKL which is unsafe here.
*/
void stop_tty(struct tty_struct *tty)
{
if (tty->stopped)
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);
}
EXPORT_SYMBOL(stop_tty);
/**
* 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 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.
*/
void start_tty(struct tty_struct *tty)
{
if (!tty->stopped || tty->flow_stopped)
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);
/* If we have a running line discipline it may need kicking */
tty_wakeup(tty);
}
EXPORT_SYMBOL(start_tty);
/**
* tty_read - read method for tty device files
* @file: pointer to tty file
* @buf: user buffer
* @count: size of user buffer
* @ppos: unused
*
* Perform the read system call function on this terminal device. Checks
* 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.
*/
static ssize_t tty_read(struct file * file, char __user * buf, size_t count,
loff_t *ppos)
{
int i;
struct tty_struct * tty;
struct inode *inode;
struct tty_ldisc *ld;
tty = (struct tty_struct *)file->private_data;
inode = file->f_path.dentry->d_inode;
if (tty_paranoia_check(tty, inode, "tty_read"))
return -EIO;
if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags)))
return -EIO;
/* 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);
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
*/
static inline ssize_t do_tty_write(
ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
struct tty_struct *tty,
struct file *file,
const char __user *buf,
size_t count)
{
ssize_t ret, written = 0;
unsigned int chunk;
ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
if (ret < 0)
return ret;
/*
* We chunk up writes into a temporary buffer. This
* simplifies low-level drivers immensely, since they
* don't have locking issues and user mode accesses.
*
* But if TTY_NO_WRITE_SPLIT is set, we should use a
* big chunk-size..
*
* The default chunk-size is 2kB, because the NTTY
* layer has problems with bigger chunks. It will
* claim to be able to handle more characters than
* it actually does.
*
* FIXME: This can probably go away now except that 64K chunks
* are too likely to fail unless switched to vmalloc...
*/
chunk = 2048;
if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
chunk = 65536;
if (count < chunk)
chunk = count;
/* write_buf/write_cnt is protected by the atomic_write_lock mutex */
if (tty->write_cnt < chunk) {
unsigned char *buf;
if (chunk < 1024)
chunk = 1024;
buf = kmalloc(chunk, GFP_KERNEL);
if (!buf) {
ret = -ENOMEM;
goto out;
}
kfree(tty->write_buf);
tty->write_cnt = chunk;
tty->write_buf = buf;
}
/* Do the write .. */
for (;;) {
size_t size = count;
if (size > chunk)
size = chunk;
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;
buf += ret;
count -= ret;
if (!count)
break;
ret = -ERESTARTSYS;
if (signal_pending(current))
break;
cond_resched();
}
if (written) {
struct inode *inode = file->f_path.dentry->d_inode;
inode->i_mtime = current_fs_time(inode->i_sb);
ret = written;
}
out:
tty_write_unlock(tty);
return ret;
}
/**
* tty_write - write method for tty device file
* @file: tty file pointer
* @buf: user data to write
* @count: bytes to write
* @ppos: unused
*
* Write data to a tty device via the line discipline.
*
* Locking:
* Locks the line discipline as required
* Writes to the tty driver are serialized by the atomic_write_lock
* and are then processed in chunks to the device. The line discipline
* write method will not be involked in parallel for each device
* The line discipline write method is called under the big
* kernel lock for historical reasons. New code should not rely on this.
*/
static ssize_t tty_write(struct file * file, const char __user * buf, size_t count,
loff_t *ppos)
{
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)
ret = -EIO;
else
ret = do_tty_write(ld->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)
{
struct file *p = NULL;
spin_lock(&redirect_lock);
if (redirect) {
get_file(redirect);
p = redirect;
}
spin_unlock(&redirect_lock);
if (p) {
ssize_t res;
res = vfs_write(p, buf, count, &p->f_pos);
fput(p);
return res;
}
return tty_write(file, buf, count, ppos);
}
static char ptychar[] = "pqrstuvwxyzabcde";
/**
* pty_line_name - generate name for a pty
* @driver: the tty driver in use
* @index: the minor number
* @p: output buffer of at least 6 bytes
*
* Generate a name from a driver reference and write it to the output
* buffer.
*
* Locking: None
*/
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);
}
/**
* pty_line_name - generate name for a tty
* @driver: the tty driver in use
* @index: the minor number
* @p: output buffer of at least 7 bytes
*
* Generate a name from a driver reference and write it to the output
* buffer.
*
* Locking: None
*/
static void tty_line_name(struct tty_driver *driver, int index, char *p)
{
sprintf(p, "%s%d", driver->name, index + driver->name_base);
}
/**
* init_dev - initialise a tty device
* @driver: tty driver we are opening a device on
* @idx: device index
* @tty: returned tty structure
*
* Prepare a tty device. This may not be a "new" clean device but
* could also be an active device. The pty drivers require special
* handling because of this.
*
* Locking:
* The function is called under the tty_mutex, which
* protects us from the tty struct or driver itself going away.
*
* On exit the tty device has the line discipline attached and
* a reference count of 1. If a pair was created for pty/tty use
* and the other was a pty master then it too has a reference count of 1.
*
* WSH 06/09/97: Rewritten to remove races and properly clean up after a
* failed open. The new code protects the open with a mutex, so it's
* really quite straightforward. The mutex locking can probably be
* relaxed for the (most common) case of reopening a tty.
*/
static int init_dev(struct tty_driver *driver, int idx,
struct tty_struct **ret_tty)
{
struct tty_struct *tty, *o_tty;
struct ktermios *tp, **tp_loc, *o_tp, **o_tp_loc;
struct ktermios *ltp, **ltp_loc, *o_ltp, **o_ltp_loc;
int retval = 0;
/* check whether we're reopening an existing tty */
if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
tty = devpts_get_tty(idx);
/*
* If we don't have a tty here on a slave open, it's because
* the master already started the close process and there's
* no relation between devpts file and tty anymore.
*/
if (!tty && driver->subtype == PTY_TYPE_SLAVE) {
retval = -EIO;
goto end_init;
}
/*
* It's safe from now on because init_dev() is called with
* tty_mutex held and release_dev() won't change tty->count
* or tty->flags without having to grab tty_mutex
*/
if (tty && driver->subtype == PTY_TYPE_MASTER)
tty = tty->link;
} else {
tty = driver->ttys[idx];
}
if (tty) goto fast_track;
/*
* 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 locked termios may be retained.)
*/
if (!try_module_get(driver->owner)) {
retval = -ENODEV;
goto end_init;
}
o_tty = NULL;
tp = o_tp = NULL;
ltp = o_ltp = NULL;
tty = alloc_tty_struct();
if(!tty)
goto fail_no_mem;
initialize_tty_struct(tty);
tty->driver = driver;
tty->index = idx;
tty_line_name(driver, idx, tty->name);
if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
tp_loc = &tty->termios;
ltp_loc = &tty->termios_locked;
} else {
tp_loc = &driver->termios[idx];
ltp_loc = &driver->termios_locked[idx];
}
if (!*tp_loc) {
tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
if (!tp)
goto free_mem_out;
*tp = driver->init_termios;
}
if (!*ltp_loc) {
ltp = kzalloc(sizeof(struct ktermios), GFP_KERNEL);
if (!ltp)
goto free_mem_out;
}
if (driver->type == TTY_DRIVER_TYPE_PTY) {
o_tty = alloc_tty_struct();
if (!o_tty)
goto free_mem_out;
initialize_tty_struct(o_tty);
o_tty->driver = driver->other;
o_tty->index = idx;
tty_line_name(driver->other, idx, o_tty->name);
if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
o_tp_loc = &o_tty->termios;
o_ltp_loc = &o_tty->termios_locked;
} else {
o_tp_loc = &driver->other->termios[idx];
o_ltp_loc = &driver->other->termios_locked[idx];
}
if (!*o_tp_loc) {
o_tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
if (!o_tp)
goto free_mem_out;
*o_tp = driver->other->init_termios;
}
if (!*o_ltp_loc) {
o_ltp = kzalloc(sizeof(struct ktermios), GFP_KERNEL);
if (!o_ltp)
goto free_mem_out;
}
/*
* Everything allocated ... set up the o_tty structure.
*/
if (!(driver->other->flags & TTY_DRIVER_DEVPTS_MEM)) {
driver->other->ttys[idx] = o_tty;
}
if (!*o_tp_loc)
*o_tp_loc = o_tp;
if (!*o_ltp_loc)
*o_ltp_loc = o_ltp;
o_tty->termios = *o_tp_loc;
o_tty->termios_locked = *o_ltp_loc;
driver->other->refcount++;
if (driver->subtype == PTY_TYPE_MASTER)
o_tty->count++;
/* Establish the links in both directions */
tty->link = o_tty;
o_tty->link = tty;
}
/*
* All structures have been allocated, so now we install them.
* Failures after this point use release_tty to clean up, so
* there's no need to null out the local pointers.
*/
if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
driver->ttys[idx] = tty;
}
if (!*tp_loc)
*tp_loc = tp;
if (!*ltp_loc)
*ltp_loc = ltp;
tty->termios = *tp_loc;
tty->termios_locked = *ltp_loc;
/* Compatibility until drivers always set this */
tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
driver->refcount++;
tty->count++;
/*
* Structures all installed ... call the ldisc open routines.
* If we fail here just call release_tty to clean up. No need
* to decrement the use counts, as release_tty doesn't care.
*/
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;
/*
* This fast open can be used if the tty is already open.
* No memory is allocated, and the only failures are from
* attempting to open a closing tty or attempting multiple
* opens on a pty master.
*/
fast_track:
if (test_bit(TTY_CLOSING, &tty->flags)) {
retval = -EIO;
goto end_init;
}
if (driver->type == TTY_DRIVER_TYPE_PTY &&
driver->subtype == PTY_TYPE_MASTER) {
/*
* special case for PTY masters: only one open permitted,
* and the slave side open count is incremented as well.
*/
if (tty->count) {
retval = -EIO;
goto end_init;
}
tty->link->count++;
}
tty->count++;
tty->driver = driver; /* N.B. why do this every time?? */
/* FIXME */
if(!test_bit(TTY_LDISC, &tty->flags))
printk(KERN_ERR "init_dev but no ldisc\n");
success:
*ret_tty = tty;
/* All paths come through here to release the mutex */
end_init:
return retval;
/* Release locally allocated memory ... nothing placed in slots */
free_mem_out:
kfree(o_tp);
if (o_tty)
free_tty_struct(o_tty);
kfree(ltp);
kfree(tp);
free_tty_struct(tty);
fail_no_mem:
module_put(driver->owner);
retval = -ENOMEM;
goto end_init;
/* 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_tty(tty, idx);
goto end_init;
}
/**
* release_one_tty - release tty structure memory
*
* Releases memory associated with a tty structure, and clears out the
* driver table slots. This function is called when a device is no longer
* in use. It also gets called when setup of a device fails.
*
* 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_one_tty(struct tty_struct *tty, int idx)
{
int devpts = tty->driver->flags & TTY_DRIVER_DEVPTS_MEM;
struct ktermios *tp;
if (!devpts)
tty->driver->ttys[idx] = NULL;
if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
tp = tty->termios;
if (!devpts)
tty->driver->termios[idx] = NULL;
kfree(tp);
tp = tty->termios_locked;
if (!devpts)
tty->driver->termios_locked[idx] = NULL;
kfree(tp);
}
tty->magic = 0;
tty->driver->refcount--;
file_list_lock();
list_del_init(&tty->tty_files);
file_list_unlock();
free_tty_struct(tty);
}
/**
* 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)
{
struct tty_driver *driver = tty->driver;
if (tty->link)
release_one_tty(tty->link, idx);
release_one_tty(tty, idx);
module_put(driver->owner);
}
/*
* Even releasing the tty structures is a tricky business.. We have
* to be very careful that the structures are all released at the
* same time, as interrupts might otherwise get the wrong pointers.
*
* 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)
{
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"))
return;
check_tty_count(tty, "release_dev");
tty_fasync(-1, filp, 0);
idx = tty->index;
pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER);
devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0;
o_tty = tty->link;
#ifdef TTY_PARANOIA_CHECK
if (idx < 0 || idx >= tty->driver->num) {
printk(KERN_DEBUG "release_dev: bad idx when trying to "
"free (%s)\n", tty->name);
return;
}
if (!(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
if (tty != tty->driver->ttys[idx]) {
printk(KERN_DEBUG "release_dev: driver.table[%d] not tty "
"for (%s)\n", idx, tty->name);
return;
}
if (tty->termios != tty->driver->termios[idx]) {
printk(KERN_DEBUG "release_dev: driver.termios[%d] not termios "
"for (%s)\n",
idx, tty->name);
return;
}
if (tty->termios_locked != tty->driver->termios_locked[idx]) {
printk(KERN_DEBUG "release_dev: driver.termios_locked[%d] not "
"termios_locked for (%s)\n",
idx, tty->name);
return;
}
}
#endif
#ifdef TTY_DEBUG_HANGUP
printk(KERN_DEBUG "release_dev of %s (tty count=%d)...",
tty_name(tty, buf), tty->count);
#endif
#ifdef TTY_PARANOIA_CHECK
if (tty->driver->other &&
!(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
if (o_tty != tty->driver->other->ttys[idx]) {
printk(KERN_DEBUG "release_dev: other->table[%d] "
"not o_tty for (%s)\n",
idx, tty->name);
return;
}
if (o_tty->termios != tty->driver->other->termios[idx]) {
printk(KERN_DEBUG "release_dev: other->termios[%d] "
"not o_termios for (%s)\n",
idx, tty->name);
return;
}
if (o_tty->termios_locked !=
tty->driver->other->termios_locked[idx]) {
printk(KERN_DEBUG "release_dev: other->termios_locked["
"%d] not o_termios_locked for (%s)\n",
idx, tty->name);
return;
}
if (o_tty->link != tty) {
printk(KERN_DEBUG "release_dev: bad pty pointers\n");
return;
}
}
#endif
if (tty->driver->close)
tty->driver->close(tty, filp);
/*
* Sanity check: if tty->count is going to zero, there shouldn't be
* any waiters on tty->read_wait or tty->write_wait. We test the
* wait queues and kick everyone out _before_ actually starting to
* close. This ensures that we won't block while releasing the tty
* structure.
*
* The test for the o_tty closing is necessary, since the master and
* slave sides may close in any order. If the slave side closes out
* first, its count will be one, since the master side holds an open.
* Thus this test wouldn't be triggered at the time the slave closes,
* so we do it now.
*
* Note that it's possible for the tty to be opened again while we're
* flushing out waiters. By recalculating the closing flags before
* each iteration we avoid any problems.
*/
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 &&
(o_tty->count <= (pty_master ? 1 : 0));
do_sleep = 0;
if (tty_closing) {
if (waitqueue_active(&tty->read_wait)) {
wake_up(&tty->read_wait);
do_sleep++;
}
if (waitqueue_active(&tty->write_wait)) {
wake_up(&tty->write_wait);
do_sleep++;
}
}
if (o_tty_closing) {
if (waitqueue_active(&o_tty->read_wait)) {
wake_up(&o_tty->read_wait);
do_sleep++;
}
if (waitqueue_active(&o_tty->write_wait)) {
wake_up(&o_tty->write_wait);
do_sleep++;
}
}
if (!do_sleep)
break;
printk(KERN_WARNING "release_dev: %s: read/write wait queue "
"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
* block, so it's safe to proceed with closing.
*/
if (pty_master) {
if (--o_tty->count < 0) {
printk(KERN_WARNING "release_dev: bad pty slave count "
"(%d) for %s\n",
o_tty->count, tty_name(o_tty, buf));
o_tty->count = 0;
}
}
if (--tty->count < 0) {
printk(KERN_WARNING "release_dev: bad tty->count (%d) for %s\n",
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
* purposes:
* - check_tty_count sees the correct number of file descriptors
* associated with this tty.
* - do_tty_hangup no longer sees this file descriptor as
* something that needs to be handled for hangups.
*/
file_kill(filp);
filp->private_data = NULL;
/*
* Perform some housekeeping before deciding whether to return.
*
* Set the TTY_CLOSING flag if this was the last open. In the
* 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)
set_bit(TTY_CLOSING, &tty->flags);
if(o_tty_closing)
set_bit(TTY_CLOSING, &o_tty->flags);
/*
* If _either_ side is closing, make sure there aren't any
* processes that still think tty or o_tty is their controlling
* tty.
*/
if (tty_closing || o_tty_closing) {
read_lock(&tasklist_lock);
session_clear_tty(tty->session);
if (o_tty)
session_clear_tty(o_tty->session);
read_unlock(&tasklist_lock);
}
mutex_unlock(&tty_mutex);
/* 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
*/
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);
}
/*
* The release_tty function takes care of the details of clearing
* the slots and preserving the termios structure.
*/
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
}
/**
* tty_open - open a tty device
* @inode: inode of device file
* @filp: file pointer to tty
*
* tty_open and tty_release keep up the tty count that contains the
* number of opens done on a tty. We cannot use the inode-count, as
* different inodes might point to the same tty.
*
* Open-counting is needed for pty masters, as well as for keeping
* track of serial lines: DTR is dropped when the last close happens.
* (This is not done solely through tty->count, now. - Ted 1/27/92)
*
* The termios state of a pty is reset on first open so that
* settings don't persist across reuse.
*
* Locking: tty_mutex protects tty, get_tty_driver and init_dev work.
* tty->count should protect the rest.
* ->siglock protects ->signal/->sighand
*/
static int tty_open(struct inode * inode, struct file * filp)
{
struct tty_struct *tty;
int noctty, retval;
struct tty_driver *driver;
int index;
dev_t device = inode->i_rdev;
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)) {
tty = get_current_tty();
if (!tty) {
mutex_unlock(&tty_mutex);
return -ENXIO;
}
driver = tty->driver;
index = tty->index;
filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
/* noctty = 1; */
goto got_driver;
}
#ifdef CONFIG_VT
if (device == MKDEV(TTY_MAJOR,0)) {
extern struct tty_driver *console_driver;
driver = console_driver;
index = fg_console;
noctty = 1;
goto got_driver;
}
#endif
if (device == MKDEV(TTYAUX_MAJOR,1)) {
driver = console_device(&index);
if (driver) {
/* Don't let /dev/console block */
filp->f_flags |= O_NONBLOCK;
noctty = 1;
goto got_driver;
}
mutex_unlock(&tty_mutex);
return -ENODEV;
}
driver = get_tty_driver(device, &index);
if (!driver) {
mutex_unlock(&tty_mutex);
return -ENODEV;
}
got_driver:
retval = init_dev(driver, index, &tty);
mutex_unlock(&tty_mutex);
if (retval)
return retval;
filp->private_data = tty;
file_move(filp, &tty->tty_files);
check_tty_count(tty, "tty_open");
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER)
noctty = 1;
#ifdef TTY_DEBUG_HANGUP
printk(KERN_DEBUG "opening %s...", tty->name);
#endif
if (!retval) {
if (tty->driver->open)
retval = tty->driver->open(tty, filp);
else
retval = -ENODEV;
}
filp->f_flags = saved_flags;
if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
retval = -EBUSY;
if (retval) {
#ifdef TTY_DEBUG_HANGUP
printk(KERN_DEBUG "error %d in opening %s...", retval,
tty->name);
#endif
release_dev(filp);
if (retval != -ERESTARTSYS)
return retval;
if (signal_pending(current))
return retval;
schedule();
/*
* Need to reset f_op in case a hangup happened.
*/
if (filp->f_op == &hung_up_tty_fops)
filp->f_op = &tty_fops;
goto retry_open;
}
mutex_lock(&tty_mutex);
spin_lock_irq(&current->sighand->siglock);
if (!noctty &&
current->signal->leader &&
!current->signal->tty &&
tty->session == NULL)
__proc_set_tty(current, tty);
spin_unlock_irq(&current->sighand->siglock);
mutex_unlock(&tty_mutex);
tty_audit_opening();
return 0;
}
#ifdef CONFIG_UNIX98_PTYS
/**
* ptmx_open - open a unix 98 pty master
* @inode: inode of device file
* @filp: file pointer to tty
*
* Allocate a unix98 pty master device from the ptmx driver.
*
* Locking: tty_mutex protects theinit_dev work. tty->count should
protect the rest.
* allocated_ptys_lock handles the list of free pty numbers
*/
static int ptmx_open(struct inode * inode, struct file * filp)
{
struct tty_struct *tty;
int retval;
int index;
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);
mutex_lock(&tty_mutex);
retval = init_dev(ptm_driver, index, &tty);
mutex_unlock(&tty_mutex);
if (retval)
goto out;
set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
filp->private_data = tty;
file_move(filp, &tty->tty_files);
retval = -ENOMEM;
if (devpts_pty_new(tty->link))
goto out1;
check_tty_count(tty, "tty_open");
retval = ptm_driver->open(tty, filp);
if (!retval) {
tty_audit_opening();
return 0;
}
out1:
release_dev(filp);
return retval;
out:
down(&allocated_ptys_lock);
idr_remove(&allocated_ptys, index);
up(&allocated_ptys_lock);
return retval;
}
#endif
/**
* tty_release - vfs callback for close
* @inode: inode of tty
* @filp: file pointer for handle to tty
*
* Called the last time each file handle is closed that references
* this tty. There may however be several such references.
*
* Locking:
* Takes bkl. See release_dev
*/
static int tty_release(struct inode * inode, struct file * filp)
{
lock_kernel();
release_dev(filp);
unlock_kernel();
return 0;
}
/**
* tty_poll - check tty status
* @filp: file being polled
* @wait: poll wait structures to update
*
* Call the line discipline polling method to obtain the poll
* status of the device.
*
* Locking: locks called line discipline but ldisc poll method
* may be re-entered freely by other callers.
*/
static unsigned int tty_poll(struct file * filp, poll_table * wait)
{
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);
tty_ldisc_deref(ld);
return ret;
}
static int tty_fasync(int fd, struct file * filp, int on)
{
struct tty_struct * tty;
int retval;
tty = (struct tty_struct *)filp->private_data;
if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_fasync"))
return 0;
retval = fasync_helper(fd, filp, on, &tty->fasync);
if (retval <= 0)
return retval;
if (on) {
enum pid_type type;
struct pid *pid;
if (!waitqueue_active(&tty->read_wait))
tty->minimum_to_wake = 1;
if (tty->pgrp) {
pid = tty->pgrp;
type = PIDTYPE_PGID;
} else {
pid = task_pid(current);
type = PIDTYPE_PID;
}
retval = __f_setown(filp, pid, type, 0);
if (retval)
return retval;
} else {
if (!tty->fasync && !waitqueue_active(&tty->read_wait))
tty->minimum_to_wake = N_TTY_BUF_SIZE;
}
return 0;
}
/**
* tiocsti - fake input character
* @tty: tty to fake input into
* @p: pointer to character
*
* Fake input to a tty device. Does the neccessary locking and
* input management.
*
* FIXME: does not honour flow control ??
*
* Locking:
* Called functions take tty_ldisc_lock
* current->signal->tty check is safe without locks
*
* FIXME: may race normal receive processing
*/
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);
tty_ldisc_deref(ld);
return 0;
}
/**
* tiocgwinsz - implement window query ioctl
* @tty; tty
* @arg: user buffer for result
*
* Copies the kernel idea of the window size into the user buffer.
*
* Locking: tty->termios_mutex is taken to ensure the winsize data
* is consistent.
*/
static int tiocgwinsz(struct tty_struct *tty, struct winsize __user * arg)
{
int err;
mutex_lock(&tty->termios_mutex);
err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
mutex_unlock(&tty->termios_mutex);
return err ? -EFAULT: 0;
}
/**
* tiocswinsz - implement window size set ioctl
* @tty; tty
* @arg: user buffer for result
*
* Copies the user idea of the window size to the kernel. Traditionally
* this is just advisory information but for the Linux console it
* 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
*/
static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty,
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<