2 * linux/drivers/char/tty_io.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
8 * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles
9 * or rs-channels. It also implements echoing, cooked mode etc.
11 * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.
13 * Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the
14 * tty_struct and tty_queue structures. Previously there was an array
15 * of 256 tty_struct's which was statically allocated, and the
16 * tty_queue structures were allocated at boot time. Both are now
17 * dynamically allocated only when the tty is open.
19 * Also restructured routines so that there is more of a separation
20 * between the high-level tty routines (tty_io.c and tty_ioctl.c) and
21 * the low-level tty routines (serial.c, pty.c, console.c). This
22 * makes for cleaner and more compact code. -TYT, 9/17/92
24 * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
25 * which can be dynamically activated and de-activated by the line
26 * discipline handling modules (like SLIP).
28 * NOTE: pay no attention to the line discipline code (yet); its
29 * interface is still subject to change in this version...
32 * Added functionality to the OPOST tty handling. No delays, but all
33 * other bits should be there.
34 * -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993.
36 * Rewrote canonical mode and added more termios flags.
37 * -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94
39 * Reorganized FASYNC support so mouse code can share it.
40 * -- ctm@ardi.com, 9Sep95
42 * New TIOCLINUX variants added.
43 * -- mj@k332.feld.cvut.cz, 19-Nov-95
45 * Restrict vt switching via ioctl()
46 * -- grif@cs.ucr.edu, 5-Dec-95
48 * Move console and virtual terminal code to more appropriate files,
49 * implement CONFIG_VT and generalize console device interface.
50 * -- Marko Kohtala <Marko.Kohtala@hut.fi>, March 97
52 * Rewrote tty_init_dev and tty_release_dev to eliminate races.
53 * -- Bill Hawes <whawes@star.net>, June 97
55 * Added devfs support.
56 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 13-Jan-1998
58 * Added support for a Unix98-style ptmx device.
59 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
61 * Reduced memory usage for older ARM systems
62 * -- Russell King <rmk@arm.linux.org.uk>
64 * Move do_SAK() into process context. Less stack use in devfs functions.
65 * alloc_tty_struct() always uses kmalloc()
66 * -- Andrew Morton <andrewm@uow.edu.eu> 17Mar01
69 #include <linux/types.h>
70 #include <linux/major.h>
71 #include <linux/errno.h>
72 #include <linux/signal.h>
73 #include <linux/fcntl.h>
74 #include <linux/sched.h>
75 #include <linux/interrupt.h>
76 #include <linux/tty.h>
77 #include <linux/tty_driver.h>
78 #include <linux/tty_flip.h>
79 #include <linux/devpts_fs.h>
80 #include <linux/file.h>
81 #include <linux/fdtable.h>
82 #include <linux/console.h>
83 #include <linux/timer.h>
84 #include <linux/ctype.h>
87 #include <linux/string.h>
88 #include <linux/slab.h>
89 #include <linux/poll.h>
90 #include <linux/proc_fs.h>
91 #include <linux/init.h>
92 #include <linux/module.h>
93 #include <linux/smp_lock.h>
94 #include <linux/device.h>
95 #include <linux/wait.h>
96 #include <linux/bitops.h>
97 #include <linux/delay.h>
98 #include <linux/seq_file.h>
100 #include <linux/uaccess.h>
101 #include <asm/system.h>
103 #include <linux/kbd_kern.h>
104 #include <linux/vt_kern.h>
105 #include <linux/selection.h>
107 #include <linux/kmod.h>
108 #include <linux/nsproxy.h>
110 #undef TTY_DEBUG_HANGUP
112 #define TTY_PARANOIA_CHECK 1
113 #define CHECK_TTY_COUNT 1
115 struct ktermios tty_std_termios = { /* for the benefit of tty drivers */
116 .c_iflag = ICRNL | IXON,
117 .c_oflag = OPOST | ONLCR,
118 .c_cflag = B38400 | CS8 | CREAD | HUPCL,
119 .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
120 ECHOCTL | ECHOKE | IEXTEN,
126 EXPORT_SYMBOL(tty_std_termios);
128 /* This list gets poked at by procfs and various bits of boot up code. This
129 could do with some rationalisation such as pulling the tty proc function
132 LIST_HEAD(tty_drivers); /* linked list of tty drivers */
134 /* Mutex to protect creating and releasing a tty. This is shared with
135 vt.c for deeply disgusting hack reasons */
136 DEFINE_MUTEX(tty_mutex);
137 EXPORT_SYMBOL(tty_mutex);
139 static void initialize_tty_struct(struct tty_struct *tty);
141 static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
142 static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
143 ssize_t redirected_tty_write(struct file *, const char __user *,
145 static unsigned int tty_poll(struct file *, poll_table *);
146 static int tty_open(struct inode *, struct file *);
147 static int tty_release(struct inode *, struct file *);
148 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
150 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
153 #define tty_compat_ioctl NULL
155 static int tty_fasync(int fd, struct file *filp, int on);
156 static void release_tty(struct tty_struct *tty, int idx);
157 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
158 static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
161 * alloc_tty_struct - allocate a tty object
163 * Return a new empty tty structure. The data fields have not
164 * been initialized in any way but has been zeroed
169 static struct tty_struct *alloc_tty_struct(void)
171 return kzalloc(sizeof(struct tty_struct), GFP_KERNEL);
175 * free_tty_struct - free a disused tty
176 * @tty: tty struct to free
178 * Free the write buffers, tty queue and tty memory itself.
180 * Locking: none. Must be called after tty is definitely unused
183 static inline void free_tty_struct(struct tty_struct *tty)
185 kfree(tty->write_buf);
186 tty_buffer_free_all(tty);
190 #define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base)
193 * tty_name - return tty naming
194 * @tty: tty structure
195 * @buf: buffer for output
197 * Convert a tty structure into a name. The name reflects the kernel
198 * naming policy and if udev is in use may not reflect user space
203 char *tty_name(struct tty_struct *tty, char *buf)
205 if (!tty) /* Hmm. NULL pointer. That's fun. */
206 strcpy(buf, "NULL tty");
208 strcpy(buf, tty->name);
212 EXPORT_SYMBOL(tty_name);
214 int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
217 #ifdef TTY_PARANOIA_CHECK
220 "null TTY for (%d:%d) in %s\n",
221 imajor(inode), iminor(inode), routine);
224 if (tty->magic != TTY_MAGIC) {
226 "bad magic number for tty struct (%d:%d) in %s\n",
227 imajor(inode), iminor(inode), routine);
234 static int check_tty_count(struct tty_struct *tty, const char *routine)
236 #ifdef CHECK_TTY_COUNT
241 list_for_each(p, &tty->tty_files) {
245 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
246 tty->driver->subtype == PTY_TYPE_SLAVE &&
247 tty->link && tty->link->count)
249 if (tty->count != count) {
250 printk(KERN_WARNING "Warning: dev (%s) tty->count(%d) "
251 "!= #fd's(%d) in %s\n",
252 tty->name, tty->count, count, routine);
260 * get_tty_driver - find device of a tty
261 * @dev_t: device identifier
262 * @index: returns the index of the tty
264 * This routine returns a tty driver structure, given a device number
265 * and also passes back the index number.
267 * Locking: caller must hold tty_mutex
270 static struct tty_driver *get_tty_driver(dev_t device, int *index)
272 struct tty_driver *p;
274 list_for_each_entry(p, &tty_drivers, tty_drivers) {
275 dev_t base = MKDEV(p->major, p->minor_start);
276 if (device < base || device >= base + p->num)
278 *index = device - base;
279 return tty_driver_kref_get(p);
284 #ifdef CONFIG_CONSOLE_POLL
287 * tty_find_polling_driver - find device of a polled tty
288 * @name: name string to match
289 * @line: pointer to resulting tty line nr
291 * This routine returns a tty driver structure, given a name
292 * and the condition that the tty driver is capable of polled
295 struct tty_driver *tty_find_polling_driver(char *name, int *line)
297 struct tty_driver *p, *res = NULL;
302 for (str = name; *str; str++)
303 if ((*str >= '0' && *str <= '9') || *str == ',')
309 tty_line = simple_strtoul(str, &str, 10);
311 mutex_lock(&tty_mutex);
312 /* Search through the tty devices to look for a match */
313 list_for_each_entry(p, &tty_drivers, tty_drivers) {
314 if (strncmp(name, p->name, len) != 0)
321 if (tty_line >= 0 && tty_line <= p->num && p->ops &&
322 p->ops->poll_init && !p->ops->poll_init(p, tty_line, str)) {
323 res = tty_driver_kref_get(p);
328 mutex_unlock(&tty_mutex);
332 EXPORT_SYMBOL_GPL(tty_find_polling_driver);
336 * tty_check_change - check for POSIX terminal changes
339 * If we try to write to, or set the state of, a terminal and we're
340 * not in the foreground, send a SIGTTOU. If the signal is blocked or
341 * ignored, go ahead and perform the operation. (POSIX 7.2)
346 int tty_check_change(struct tty_struct *tty)
351 if (current->signal->tty != tty)
354 spin_lock_irqsave(&tty->ctrl_lock, flags);
357 printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");
360 if (task_pgrp(current) == tty->pgrp)
362 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
363 if (is_ignored(SIGTTOU))
365 if (is_current_pgrp_orphaned()) {
369 kill_pgrp(task_pgrp(current), SIGTTOU, 1);
370 set_thread_flag(TIF_SIGPENDING);
375 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
379 EXPORT_SYMBOL(tty_check_change);
381 static ssize_t hung_up_tty_read(struct file *file, char __user *buf,
382 size_t count, loff_t *ppos)
387 static ssize_t hung_up_tty_write(struct file *file, const char __user *buf,
388 size_t count, loff_t *ppos)
393 /* No kernel lock held - none needed ;) */
394 static unsigned int hung_up_tty_poll(struct file *filp, poll_table *wait)
396 return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM;
399 static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
402 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
405 static long hung_up_tty_compat_ioctl(struct file *file,
406 unsigned int cmd, unsigned long arg)
408 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
411 static const struct file_operations tty_fops = {
416 .unlocked_ioctl = tty_ioctl,
417 .compat_ioctl = tty_compat_ioctl,
419 .release = tty_release,
420 .fasync = tty_fasync,
423 static const struct file_operations console_fops = {
426 .write = redirected_tty_write,
428 .unlocked_ioctl = tty_ioctl,
429 .compat_ioctl = tty_compat_ioctl,
431 .release = tty_release,
432 .fasync = tty_fasync,
435 static const struct file_operations hung_up_tty_fops = {
437 .read = hung_up_tty_read,
438 .write = hung_up_tty_write,
439 .poll = hung_up_tty_poll,
440 .unlocked_ioctl = hung_up_tty_ioctl,
441 .compat_ioctl = hung_up_tty_compat_ioctl,
442 .release = tty_release,
445 static DEFINE_SPINLOCK(redirect_lock);
446 static struct file *redirect;
449 * tty_wakeup - request more data
452 * Internal and external helper for wakeups of tty. This function
453 * informs the line discipline if present that the driver is ready
454 * to receive more output data.
457 void tty_wakeup(struct tty_struct *tty)
459 struct tty_ldisc *ld;
461 if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
462 ld = tty_ldisc_ref(tty);
464 if (ld->ops->write_wakeup)
465 ld->ops->write_wakeup(tty);
469 wake_up_interruptible(&tty->write_wait);
472 EXPORT_SYMBOL_GPL(tty_wakeup);
475 * tty_ldisc_flush - flush line discipline queue
478 * Flush the line discipline queue (if any) for this tty. If there
479 * is no line discipline active this is a no-op.
482 void tty_ldisc_flush(struct tty_struct *tty)
484 struct tty_ldisc *ld = tty_ldisc_ref(tty);
486 if (ld->ops->flush_buffer)
487 ld->ops->flush_buffer(tty);
490 tty_buffer_flush(tty);
493 EXPORT_SYMBOL_GPL(tty_ldisc_flush);
496 * tty_reset_termios - reset terminal state
499 * Restore a terminal to the driver default state
502 static void tty_reset_termios(struct tty_struct *tty)
504 mutex_lock(&tty->termios_mutex);
505 *tty->termios = tty->driver->init_termios;
506 tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
507 tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
508 mutex_unlock(&tty->termios_mutex);
512 * do_tty_hangup - actual handler for hangup events
515 * This can be called by the "eventd" kernel thread. That is process
516 * synchronous but doesn't hold any locks, so we need to make sure we
517 * have the appropriate locks for what we're doing.
519 * The hangup event clears any pending redirections onto the hung up
520 * device. It ensures future writes will error and it does the needed
521 * line discipline hangup and signal delivery. The tty object itself
526 * redirect lock for undoing redirection
527 * file list lock for manipulating list of ttys
528 * tty_ldisc_lock from called functions
529 * termios_mutex resetting termios data
530 * tasklist_lock to walk task list for hangup event
531 * ->siglock to protect ->signal/->sighand
533 static void do_tty_hangup(struct work_struct *work)
535 struct tty_struct *tty =
536 container_of(work, struct tty_struct, hangup_work);
537 struct file *cons_filp = NULL;
538 struct file *filp, *f = NULL;
539 struct task_struct *p;
540 struct tty_ldisc *ld;
541 int closecount = 0, n;
548 /* inuse_filps is protected by the single kernel lock */
551 spin_lock(&redirect_lock);
552 if (redirect && redirect->private_data == tty) {
556 spin_unlock(&redirect_lock);
558 check_tty_count(tty, "do_tty_hangup");
560 /* This breaks for file handles being sent over AF_UNIX sockets ? */
561 list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) {
562 if (filp->f_op->write == redirected_tty_write)
564 if (filp->f_op->write != tty_write)
567 tty_fasync(-1, filp, 0); /* can't block */
568 filp->f_op = &hung_up_tty_fops;
572 * FIXME! What are the locking issues here? This may me overdoing
573 * things... This question is especially important now that we've
574 * removed the irqlock.
576 ld = tty_ldisc_ref(tty);
578 /* We may have no line discipline at this point */
579 if (ld->ops->flush_buffer)
580 ld->ops->flush_buffer(tty);
581 tty_driver_flush_buffer(tty);
582 if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) &&
583 ld->ops->write_wakeup)
584 ld->ops->write_wakeup(tty);
586 ld->ops->hangup(tty);
589 * FIXME: Once we trust the LDISC code better we can wait here for
590 * ldisc completion and fix the driver call race
592 wake_up_interruptible(&tty->write_wait);
593 wake_up_interruptible(&tty->read_wait);
595 * Shutdown the current line discipline, and reset it to
598 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
599 tty_reset_termios(tty);
600 /* Defer ldisc switch */
601 /* tty_deferred_ldisc_switch(N_TTY);
603 This should get done automatically when the port closes and
604 tty_release is called */
606 read_lock(&tasklist_lock);
608 do_each_pid_task(tty->session, PIDTYPE_SID, p) {
609 spin_lock_irq(&p->sighand->siglock);
610 if (p->signal->tty == tty) {
611 p->signal->tty = NULL;
612 /* We defer the dereferences outside fo
616 if (!p->signal->leader) {
617 spin_unlock_irq(&p->sighand->siglock);
620 __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
621 __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
622 put_pid(p->signal->tty_old_pgrp); /* A noop */
623 spin_lock_irqsave(&tty->ctrl_lock, flags);
625 p->signal->tty_old_pgrp = get_pid(tty->pgrp);
626 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
627 spin_unlock_irq(&p->sighand->siglock);
628 } while_each_pid_task(tty->session, PIDTYPE_SID, p);
630 read_unlock(&tasklist_lock);
632 spin_lock_irqsave(&tty->ctrl_lock, flags);
634 put_pid(tty->session);
638 tty->ctrl_status = 0;
639 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
641 /* Account for the p->signal references we killed */
646 * If one of the devices matches a console pointer, we
647 * cannot just call hangup() because that will cause
648 * tty->count and state->count to go out of sync.
649 * So we just call close() the right number of times.
653 for (n = 0; n < closecount; n++)
654 tty->ops->close(tty, cons_filp);
655 } else if (tty->ops->hangup)
656 (tty->ops->hangup)(tty);
658 * We don't want to have driver/ldisc interactions beyond
659 * the ones we did here. The driver layer expects no
660 * calls after ->hangup() from the ldisc side. However we
661 * can't yet guarantee all that.
663 set_bit(TTY_HUPPED, &tty->flags);
665 tty_ldisc_enable(tty);
674 * tty_hangup - trigger a hangup event
675 * @tty: tty to hangup
677 * A carrier loss (virtual or otherwise) has occurred on this like
678 * schedule a hangup sequence to run after this event.
681 void tty_hangup(struct tty_struct *tty)
683 #ifdef TTY_DEBUG_HANGUP
685 printk(KERN_DEBUG "%s hangup...\n", tty_name(tty, buf));
687 schedule_work(&tty->hangup_work);
690 EXPORT_SYMBOL(tty_hangup);
693 * tty_vhangup - process vhangup
694 * @tty: tty to hangup
696 * The user has asked via system call for the terminal to be hung up.
697 * We do this synchronously so that when the syscall returns the process
698 * is complete. That guarantee is necessary for security reasons.
701 void tty_vhangup(struct tty_struct *tty)
703 #ifdef TTY_DEBUG_HANGUP
706 printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf));
708 do_tty_hangup(&tty->hangup_work);
711 EXPORT_SYMBOL(tty_vhangup);
714 * tty_vhangup_self - process vhangup for own ctty
716 * Perform a vhangup on the current controlling tty
719 void tty_vhangup_self(void)
721 struct tty_struct *tty;
723 tty = get_current_tty();
731 * tty_hung_up_p - was tty hung up
732 * @filp: file pointer of tty
734 * Return true if the tty has been subject to a vhangup or a carrier
738 int tty_hung_up_p(struct file *filp)
740 return (filp->f_op == &hung_up_tty_fops);
743 EXPORT_SYMBOL(tty_hung_up_p);
745 static void session_clear_tty(struct pid *session)
747 struct task_struct *p;
748 do_each_pid_task(session, PIDTYPE_SID, p) {
750 } while_each_pid_task(session, PIDTYPE_SID, p);
754 * disassociate_ctty - disconnect controlling tty
755 * @on_exit: true if exiting so need to "hang up" the session
757 * This function is typically called only by the session leader, when
758 * it wants to disassociate itself from its controlling tty.
760 * It performs the following functions:
761 * (1) Sends a SIGHUP and SIGCONT to the foreground process group
762 * (2) Clears the tty from being controlling the session
763 * (3) Clears the controlling tty for all processes in the
766 * The argument on_exit is set to 1 if called when a process is
767 * exiting; it is 0 if called by the ioctl TIOCNOTTY.
770 * BKL is taken for hysterical raisins
771 * tty_mutex is taken to protect tty
772 * ->siglock is taken to protect ->signal/->sighand
773 * tasklist_lock is taken to walk process list for sessions
774 * ->siglock is taken to protect ->signal/->sighand
777 void disassociate_ctty(int on_exit)
779 struct tty_struct *tty;
780 struct pid *tty_pgrp = NULL;
783 tty = get_current_tty();
785 tty_pgrp = get_pid(tty->pgrp);
787 if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)
791 } else if (on_exit) {
792 struct pid *old_pgrp;
793 spin_lock_irq(¤t->sighand->siglock);
794 old_pgrp = current->signal->tty_old_pgrp;
795 current->signal->tty_old_pgrp = NULL;
796 spin_unlock_irq(¤t->sighand->siglock);
798 kill_pgrp(old_pgrp, SIGHUP, on_exit);
799 kill_pgrp(old_pgrp, SIGCONT, on_exit);
805 kill_pgrp(tty_pgrp, SIGHUP, on_exit);
807 kill_pgrp(tty_pgrp, SIGCONT, on_exit);
811 spin_lock_irq(¤t->sighand->siglock);
812 put_pid(current->signal->tty_old_pgrp);
813 current->signal->tty_old_pgrp = NULL;
814 spin_unlock_irq(¤t->sighand->siglock);
816 tty = get_current_tty();
819 spin_lock_irqsave(&tty->ctrl_lock, flags);
820 put_pid(tty->session);
824 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
827 #ifdef TTY_DEBUG_HANGUP
828 printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
833 /* Now clear signal->tty under the lock */
834 read_lock(&tasklist_lock);
835 session_clear_tty(task_session(current));
836 read_unlock(&tasklist_lock);
841 * no_tty - Ensure the current process does not have a controlling tty
845 struct task_struct *tsk = current;
847 if (tsk->signal->leader)
848 disassociate_ctty(0);
855 * stop_tty - propagate flow control
858 * Perform flow control to the driver. For PTY/TTY pairs we
859 * must also propagate the TIOCKPKT status. May be called
860 * on an already stopped device and will not re-call the driver
863 * This functionality is used by both the line disciplines for
864 * halting incoming flow and by the driver. It may therefore be
865 * called from any context, may be under the tty atomic_write_lock
869 * Uses the tty control lock internally
872 void stop_tty(struct tty_struct *tty)
875 spin_lock_irqsave(&tty->ctrl_lock, flags);
877 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
881 if (tty->link && tty->link->packet) {
882 tty->ctrl_status &= ~TIOCPKT_START;
883 tty->ctrl_status |= TIOCPKT_STOP;
884 wake_up_interruptible(&tty->link->read_wait);
886 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
888 (tty->ops->stop)(tty);
891 EXPORT_SYMBOL(stop_tty);
894 * start_tty - propagate flow control
897 * Start a tty that has been stopped if at all possible. Perform
898 * any necessary wakeups and propagate the TIOCPKT status. If this
899 * is the tty was previous stopped and is being started then the
900 * driver start method is invoked and the line discipline woken.
906 void start_tty(struct tty_struct *tty)
909 spin_lock_irqsave(&tty->ctrl_lock, flags);
910 if (!tty->stopped || tty->flow_stopped) {
911 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
915 if (tty->link && tty->link->packet) {
916 tty->ctrl_status &= ~TIOCPKT_STOP;
917 tty->ctrl_status |= TIOCPKT_START;
918 wake_up_interruptible(&tty->link->read_wait);
920 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
922 (tty->ops->start)(tty);
923 /* If we have a running line discipline it may need kicking */
927 EXPORT_SYMBOL(start_tty);
930 * tty_read - read method for tty device files
931 * @file: pointer to tty file
933 * @count: size of user buffer
936 * Perform the read system call function on this terminal device. Checks
937 * for hung up devices before calling the line discipline method.
940 * Locks the line discipline internally while needed. Multiple
941 * read calls may be outstanding in parallel.
944 static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
948 struct tty_struct *tty;
950 struct tty_ldisc *ld;
952 tty = (struct tty_struct *)file->private_data;
953 inode = file->f_path.dentry->d_inode;
954 if (tty_paranoia_check(tty, inode, "tty_read"))
956 if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags)))
959 /* We want to wait for the line discipline to sort out in this
961 ld = tty_ldisc_ref_wait(tty);
963 i = (ld->ops->read)(tty, file, buf, count);
968 inode->i_atime = current_fs_time(inode->i_sb);
972 void tty_write_unlock(struct tty_struct *tty)
974 mutex_unlock(&tty->atomic_write_lock);
975 wake_up_interruptible(&tty->write_wait);
978 int tty_write_lock(struct tty_struct *tty, int ndelay)
980 if (!mutex_trylock(&tty->atomic_write_lock)) {
983 if (mutex_lock_interruptible(&tty->atomic_write_lock))
990 * Split writes up in sane blocksizes to avoid
991 * denial-of-service type attacks
993 static inline ssize_t do_tty_write(
994 ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
995 struct tty_struct *tty,
997 const char __user *buf,
1000 ssize_t ret, written = 0;
1003 ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
1008 * We chunk up writes into a temporary buffer. This
1009 * simplifies low-level drivers immensely, since they
1010 * don't have locking issues and user mode accesses.
1012 * But if TTY_NO_WRITE_SPLIT is set, we should use a
1015 * The default chunk-size is 2kB, because the NTTY
1016 * layer has problems with bigger chunks. It will
1017 * claim to be able to handle more characters than
1020 * FIXME: This can probably go away now except that 64K chunks
1021 * are too likely to fail unless switched to vmalloc...
1024 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
1029 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
1030 if (tty->write_cnt < chunk) {
1036 buf = kmalloc(chunk, GFP_KERNEL);
1041 kfree(tty->write_buf);
1042 tty->write_cnt = chunk;
1043 tty->write_buf = buf;
1046 /* Do the write .. */
1048 size_t size = count;
1052 if (copy_from_user(tty->write_buf, buf, size))
1054 ret = write(tty, file, tty->write_buf, size);
1063 if (signal_pending(current))
1068 struct inode *inode = file->f_path.dentry->d_inode;
1069 inode->i_mtime = current_fs_time(inode->i_sb);
1073 tty_write_unlock(tty);
1078 * tty_write_message - write a message to a certain tty, not just the console.
1079 * @tty: the destination tty_struct
1080 * @msg: the message to write
1082 * This is used for messages that need to be redirected to a specific tty.
1083 * We don't put it into the syslog queue right now maybe in the future if
1086 * We must still hold the BKL and test the CLOSING flag for the moment.
1089 void tty_write_message(struct tty_struct *tty, char *msg)
1093 mutex_lock(&tty->atomic_write_lock);
1094 if (tty->ops->write && !test_bit(TTY_CLOSING, &tty->flags))
1095 tty->ops->write(tty, msg, strlen(msg));
1096 tty_write_unlock(tty);
1104 * tty_write - write method for tty device file
1105 * @file: tty file pointer
1106 * @buf: user data to write
1107 * @count: bytes to write
1110 * Write data to a tty device via the line discipline.
1113 * Locks the line discipline as required
1114 * Writes to the tty driver are serialized by the atomic_write_lock
1115 * and are then processed in chunks to the device. The line discipline
1116 * write method will not be involked in parallel for each device
1117 * The line discipline write method is called under the big
1118 * kernel lock for historical reasons. New code should not rely on this.
1121 static ssize_t tty_write(struct file *file, const char __user *buf,
1122 size_t count, loff_t *ppos)
1124 struct tty_struct *tty;
1125 struct inode *inode = file->f_path.dentry->d_inode;
1127 struct tty_ldisc *ld;
1129 tty = (struct tty_struct *)file->private_data;
1130 if (tty_paranoia_check(tty, inode, "tty_write"))
1132 if (!tty || !tty->ops->write ||
1133 (test_bit(TTY_IO_ERROR, &tty->flags)))
1135 /* Short term debug to catch buggy drivers */
1136 if (tty->ops->write_room == NULL)
1137 printk(KERN_ERR "tty driver %s lacks a write_room method.\n",
1139 ld = tty_ldisc_ref_wait(tty);
1140 if (!ld->ops->write)
1143 ret = do_tty_write(ld->ops->write, tty, file, buf, count);
1144 tty_ldisc_deref(ld);
1148 ssize_t redirected_tty_write(struct file *file, const char __user *buf,
1149 size_t count, loff_t *ppos)
1151 struct file *p = NULL;
1153 spin_lock(&redirect_lock);
1158 spin_unlock(&redirect_lock);
1162 res = vfs_write(p, buf, count, &p->f_pos);
1166 return tty_write(file, buf, count, ppos);
1169 static char ptychar[] = "pqrstuvwxyzabcde";
1172 * pty_line_name - generate name for a pty
1173 * @driver: the tty driver in use
1174 * @index: the minor number
1175 * @p: output buffer of at least 6 bytes
1177 * Generate a name from a driver reference and write it to the output
1182 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1184 int i = index + driver->name_base;
1185 /* ->name is initialized to "ttyp", but "tty" is expected */
1186 sprintf(p, "%s%c%x",
1187 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1188 ptychar[i >> 4 & 0xf], i & 0xf);
1192 * tty_line_name - generate name for a tty
1193 * @driver: the tty driver in use
1194 * @index: the minor number
1195 * @p: output buffer of at least 7 bytes
1197 * Generate a name from a driver reference and write it to the output
1202 static void tty_line_name(struct tty_driver *driver, int index, char *p)
1204 sprintf(p, "%s%d", driver->name, index + driver->name_base);
1208 * tty_driver_lookup_tty() - find an existing tty, if any
1209 * @driver: the driver for the tty
1210 * @idx: the minor number
1212 * Return the tty, if found or ERR_PTR() otherwise.
1214 * Locking: tty_mutex must be held. If tty is found, the mutex must
1215 * be held until the 'fast-open' is also done. Will change once we
1216 * have refcounting in the driver and per driver locking
1218 struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver, int idx)
1220 struct tty_struct *tty;
1222 if (driver->ops->lookup)
1223 return driver->ops->lookup(driver, idx);
1225 tty = driver->ttys[idx];
1230 * tty_driver_install_tty() - install a tty entry in the driver
1231 * @driver: the driver for the tty
1234 * Install a tty object into the driver tables. The tty->index field
1235 * will be set by the time this is called.
1237 * Locking: tty_mutex for now
1239 static int tty_driver_install_tty(struct tty_driver *driver,
1240 struct tty_struct *tty)
1242 if (driver->ops->install)
1243 return driver->ops->install(driver, tty);
1244 driver->ttys[tty->index] = tty;
1249 * tty_driver_remove_tty() - remove a tty from the driver tables
1250 * @driver: the driver for the tty
1251 * @idx: the minor number
1253 * Remvoe a tty object from the driver tables. The tty->index field
1254 * will be set by the time this is called.
1256 * Locking: tty_mutex for now
1258 static void tty_driver_remove_tty(struct tty_driver *driver,
1259 struct tty_struct *tty)
1261 if (driver->ops->remove)
1262 driver->ops->remove(driver, tty);
1264 driver->ttys[tty->index] = NULL;
1268 * tty_reopen() - fast re-open of an open tty
1269 * @tty - the tty to open
1271 * Return 0 on success, -errno on error.
1273 * Locking: tty_mutex must be held from the time the tty was found
1274 * till this open completes.
1276 static int tty_reopen(struct tty_struct *tty)
1278 struct tty_driver *driver = tty->driver;
1280 if (test_bit(TTY_CLOSING, &tty->flags))
1283 if (driver->type == TTY_DRIVER_TYPE_PTY &&
1284 driver->subtype == PTY_TYPE_MASTER) {
1286 * special case for PTY masters: only one open permitted,
1287 * and the slave side open count is incremented as well.
1295 tty->driver = driver; /* N.B. why do this every time?? */
1297 WARN_ON(!test_bit(TTY_LDISC, &tty->flags));
1303 * tty_init_dev - initialise a tty device
1304 * @driver: tty driver we are opening a device on
1305 * @idx: device index
1306 * @ret_tty: returned tty structure
1307 * @first_ok: ok to open a new device (used by ptmx)
1309 * Prepare a tty device. This may not be a "new" clean device but
1310 * could also be an active device. The pty drivers require special
1311 * handling because of this.
1314 * The function is called under the tty_mutex, which
1315 * protects us from the tty struct or driver itself going away.
1317 * On exit the tty device has the line discipline attached and
1318 * a reference count of 1. If a pair was created for pty/tty use
1319 * and the other was a pty master then it too has a reference count of 1.
1321 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1322 * failed open. The new code protects the open with a mutex, so it's
1323 * really quite straightforward. The mutex locking can probably be
1324 * relaxed for the (most common) case of reopening a tty.
1327 int tty_init_dev(struct tty_driver *driver, int idx,
1328 struct tty_struct **ret_tty, int first_ok)
1330 struct tty_struct *tty, *o_tty;
1331 struct ktermios *tp, **tp_loc, *o_tp, **o_tp_loc;
1332 struct ktermios *ltp, **ltp_loc, *o_ltp, **o_ltp_loc;
1335 /* check whether we're reopening an existing tty */
1336 tty = tty_driver_lookup_tty(driver, idx);
1338 retval = PTR_ERR(tty);
1343 retval = tty_reopen(tty);
1350 /* Check if pty master is being opened multiple times */
1351 if (driver->subtype == PTY_TYPE_MASTER &&
1352 (driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) {
1357 * First time open is complex, especially for PTY devices.
1358 * This code guarantees that either everything succeeds and the
1359 * TTY is ready for operation, or else the table slots are vacated
1360 * and the allocated memory released. (Except that the termios
1361 * and locked termios may be retained.)
1364 if (!try_module_get(driver->owner)) {
1373 tty = alloc_tty_struct();
1376 initialize_tty_struct(tty);
1377 tty->driver = driver;
1378 tty->ops = driver->ops;
1380 tty_line_name(driver, idx, tty->name);
1382 if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
1383 tp_loc = &tty->termios;
1384 ltp_loc = &tty->termios_locked;
1386 tp_loc = &driver->termios[idx];
1387 ltp_loc = &driver->termios_locked[idx];
1391 tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
1394 *tp = driver->init_termios;
1398 ltp = kzalloc(sizeof(struct ktermios), GFP_KERNEL);
1403 if (driver->type == TTY_DRIVER_TYPE_PTY) {
1404 o_tty = alloc_tty_struct();
1407 if (!try_module_get(driver->other->owner)) {
1408 /* This cannot in fact currently happen */
1409 free_tty_struct(o_tty);
1413 initialize_tty_struct(o_tty);
1414 o_tty->driver = driver->other;
1415 o_tty->ops = driver->ops;
1417 tty_line_name(driver->other, idx, o_tty->name);
1419 if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
1420 o_tp_loc = &o_tty->termios;
1421 o_ltp_loc = &o_tty->termios_locked;
1423 o_tp_loc = &driver->other->termios[idx];
1424 o_ltp_loc = &driver->other->termios_locked[idx];
1428 o_tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
1431 *o_tp = driver->other->init_termios;
1435 o_ltp = kzalloc(sizeof(struct ktermios), GFP_KERNEL);
1441 * Everything allocated ... set up the o_tty structure.
1443 if (!(driver->other->flags & TTY_DRIVER_DEVPTS_MEM))
1444 driver->other->ttys[idx] = o_tty;
1449 o_tty->termios = *o_tp_loc;
1450 o_tty->termios_locked = *o_ltp_loc;
1451 tty_driver_kref_get(driver->other);
1452 if (driver->subtype == PTY_TYPE_MASTER)
1455 /* Establish the links in both directions */
1461 * All structures have been allocated, so now we install them.
1462 * Failures after this point use release_tty to clean up, so
1463 * there's no need to null out the local pointers.
1470 tty->termios = *tp_loc;
1471 tty->termios_locked = *ltp_loc;
1472 /* Compatibility until drivers always set this */
1473 tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
1474 tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
1475 tty_driver_kref_get(driver);
1478 if (tty_driver_install_tty(driver, tty) < 0)
1479 goto release_mem_out;
1482 * Structures all installed ... call the ldisc open routines.
1483 * If we fail here just call release_tty to clean up. No need
1484 * to decrement the use counts, as release_tty doesn't care.
1487 retval = tty_ldisc_setup(tty, o_tty);
1490 goto release_mem_out;
1493 /* All paths come through here to release the mutex */
1497 /* Release locally allocated memory ... nothing placed in slots */
1501 module_put(o_tty->driver->owner);
1502 free_tty_struct(o_tty);
1506 free_tty_struct(tty);
1509 module_put(driver->owner);
1513 /* call the tty release_tty routine to clean out this slot */
1515 if (printk_ratelimit())
1516 printk(KERN_INFO "tty_init_dev: ldisc open failed, "
1517 "clearing slot %d\n", idx);
1518 release_tty(tty, idx);
1522 void tty_free_termios(struct tty_struct *tty)
1524 struct ktermios *tp;
1525 int idx = tty->index;
1526 /* Kill this flag and push into drivers for locking etc */
1527 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
1528 /* FIXME: Locking on ->termios array */
1530 tty->driver->termios[idx] = NULL;
1533 tp = tty->termios_locked;
1534 tty->driver->termios_locked[idx] = NULL;
1538 EXPORT_SYMBOL(tty_free_termios);
1540 void tty_shutdown(struct tty_struct *tty)
1542 tty_driver_remove_tty(tty->driver, tty);
1543 tty_free_termios(tty);
1545 EXPORT_SYMBOL(tty_shutdown);
1548 * release_one_tty - release tty structure memory
1549 * @kref: kref of tty we are obliterating
1551 * Releases memory associated with a tty structure, and clears out the
1552 * driver table slots. This function is called when a device is no longer
1553 * in use. It also gets called when setup of a device fails.
1556 * tty_mutex - sometimes only
1557 * takes the file list lock internally when working on the list
1558 * of ttys that the driver keeps.
1560 static void release_one_tty(struct kref *kref)
1562 struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1563 struct tty_driver *driver = tty->driver;
1565 if (tty->ops->shutdown)
1566 tty->ops->shutdown(tty);
1570 tty_driver_kref_put(driver);
1571 module_put(driver->owner);
1574 list_del_init(&tty->tty_files);
1577 free_tty_struct(tty);
1581 * tty_kref_put - release a tty kref
1584 * Release a reference to a tty device and if need be let the kref
1585 * layer destruct the object for us
1588 void tty_kref_put(struct tty_struct *tty)
1591 kref_put(&tty->kref, release_one_tty);
1593 EXPORT_SYMBOL(tty_kref_put);
1596 * release_tty - release tty structure memory
1598 * Release both @tty and a possible linked partner (think pty pair),
1599 * and decrement the refcount of the backing module.
1602 * tty_mutex - sometimes only
1603 * takes the file list lock internally when working on the list
1604 * of ttys that the driver keeps.
1605 * FIXME: should we require tty_mutex is held here ??
1608 static void release_tty(struct tty_struct *tty, int idx)
1610 /* This should always be true but check for the moment */
1611 WARN_ON(tty->index != idx);
1614 tty_kref_put(tty->link);
1619 * Even releasing the tty structures is a tricky business.. We have
1620 * to be very careful that the structures are all released at the
1621 * same time, as interrupts might otherwise get the wrong pointers.
1623 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1624 * lead to double frees or releasing memory still in use.
1626 void tty_release_dev(struct file *filp)
1628 struct tty_struct *tty, *o_tty;
1629 int pty_master, tty_closing, o_tty_closing, do_sleep;
1634 tty = (struct tty_struct *)filp->private_data;
1635 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode,
1639 check_tty_count(tty, "tty_release_dev");
1641 tty_fasync(-1, filp, 0);
1644 pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1645 tty->driver->subtype == PTY_TYPE_MASTER);
1646 devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0;
1649 #ifdef TTY_PARANOIA_CHECK
1650 if (idx < 0 || idx >= tty->driver->num) {
1651 printk(KERN_DEBUG "tty_release_dev: bad idx when trying to "
1652 "free (%s)\n", tty->name);
1656 if (tty != tty->driver->ttys[idx]) {
1657 printk(KERN_DEBUG "tty_release_dev: driver.table[%d] not tty "
1658 "for (%s)\n", idx, tty->name);
1661 if (tty->termios != tty->driver->termios[idx]) {
1662 printk(KERN_DEBUG "tty_release_dev: driver.termios[%d] not termios "
1667 if (tty->termios_locked != tty->driver->termios_locked[idx]) {
1668 printk(KERN_DEBUG "tty_release_dev: driver.termios_locked[%d] not "
1669 "termios_locked for (%s)\n",
1676 #ifdef TTY_DEBUG_HANGUP
1677 printk(KERN_DEBUG "tty_release_dev of %s (tty count=%d)...",
1678 tty_name(tty, buf), tty->count);
1681 #ifdef TTY_PARANOIA_CHECK
1682 if (tty->driver->other &&
1683 !(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
1684 if (o_tty != tty->driver->other->ttys[idx]) {
1685 printk(KERN_DEBUG "tty_release_dev: other->table[%d] "
1686 "not o_tty for (%s)\n",
1690 if (o_tty->termios != tty->driver->other->termios[idx]) {
1691 printk(KERN_DEBUG "tty_release_dev: other->termios[%d] "
1692 "not o_termios for (%s)\n",
1696 if (o_tty->termios_locked !=
1697 tty->driver->other->termios_locked[idx]) {
1698 printk(KERN_DEBUG "tty_release_dev: other->termios_locked["
1699 "%d] not o_termios_locked for (%s)\n",
1703 if (o_tty->link != tty) {
1704 printk(KERN_DEBUG "tty_release_dev: bad pty pointers\n");
1709 if (tty->ops->close)
1710 tty->ops->close(tty, filp);
1713 * Sanity check: if tty->count is going to zero, there shouldn't be
1714 * any waiters on tty->read_wait or tty->write_wait. We test the
1715 * wait queues and kick everyone out _before_ actually starting to
1716 * close. This ensures that we won't block while releasing the tty
1719 * The test for the o_tty closing is necessary, since the master and
1720 * slave sides may close in any order. If the slave side closes out
1721 * first, its count will be one, since the master side holds an open.
1722 * Thus this test wouldn't be triggered at the time the slave closes,
1725 * Note that it's possible for the tty to be opened again while we're
1726 * flushing out waiters. By recalculating the closing flags before
1727 * each iteration we avoid any problems.
1730 /* Guard against races with tty->count changes elsewhere and
1731 opens on /dev/tty */
1733 mutex_lock(&tty_mutex);
1734 tty_closing = tty->count <= 1;
1735 o_tty_closing = o_tty &&
1736 (o_tty->count <= (pty_master ? 1 : 0));
1740 if (waitqueue_active(&tty->read_wait)) {
1741 wake_up(&tty->read_wait);
1744 if (waitqueue_active(&tty->write_wait)) {
1745 wake_up(&tty->write_wait);
1749 if (o_tty_closing) {
1750 if (waitqueue_active(&o_tty->read_wait)) {
1751 wake_up(&o_tty->read_wait);
1754 if (waitqueue_active(&o_tty->write_wait)) {
1755 wake_up(&o_tty->write_wait);
1762 printk(KERN_WARNING "tty_release_dev: %s: read/write wait queue "
1763 "active!\n", tty_name(tty, buf));
1764 mutex_unlock(&tty_mutex);
1769 * The closing flags are now consistent with the open counts on
1770 * both sides, and we've completed the last operation that could
1771 * block, so it's safe to proceed with closing.
1774 if (--o_tty->count < 0) {
1775 printk(KERN_WARNING "tty_release_dev: bad pty slave count "
1777 o_tty->count, tty_name(o_tty, buf));
1781 if (--tty->count < 0) {
1782 printk(KERN_WARNING "tty_release_dev: bad tty->count (%d) for %s\n",
1783 tty->count, tty_name(tty, buf));
1788 * We've decremented tty->count, so we need to remove this file
1789 * descriptor off the tty->tty_files list; this serves two
1791 * - check_tty_count sees the correct number of file descriptors
1792 * associated with this tty.
1793 * - do_tty_hangup no longer sees this file descriptor as
1794 * something that needs to be handled for hangups.
1797 filp->private_data = NULL;
1800 * Perform some housekeeping before deciding whether to return.
1802 * Set the TTY_CLOSING flag if this was the last open. In the
1803 * case of a pty we may have to wait around for the other side
1804 * to close, and TTY_CLOSING makes sure we can't be reopened.
1807 set_bit(TTY_CLOSING, &tty->flags);
1809 set_bit(TTY_CLOSING, &o_tty->flags);
1812 * If _either_ side is closing, make sure there aren't any
1813 * processes that still think tty or o_tty is their controlling
1816 if (tty_closing || o_tty_closing) {
1817 read_lock(&tasklist_lock);
1818 session_clear_tty(tty->session);
1820 session_clear_tty(o_tty->session);
1821 read_unlock(&tasklist_lock);
1824 mutex_unlock(&tty_mutex);
1826 /* check whether both sides are closing ... */
1827 if (!tty_closing || (o_tty && !o_tty_closing))
1830 #ifdef TTY_DEBUG_HANGUP
1831 printk(KERN_DEBUG "freeing tty structure...");
1834 * Ask the line discipline code to release its structures
1836 tty_ldisc_release(tty, o_tty);
1838 * The release_tty function takes care of the details of clearing
1839 * the slots and preserving the termios structure.
1841 release_tty(tty, idx);
1843 /* Make this pty number available for reallocation */
1845 devpts_kill_index(idx);
1849 * __tty_open - open a tty device
1850 * @inode: inode of device file
1851 * @filp: file pointer to tty
1853 * tty_open and tty_release keep up the tty count that contains the
1854 * number of opens done on a tty. We cannot use the inode-count, as
1855 * different inodes might point to the same tty.
1857 * Open-counting is needed for pty masters, as well as for keeping
1858 * track of serial lines: DTR is dropped when the last close happens.
1859 * (This is not done solely through tty->count, now. - Ted 1/27/92)
1861 * The termios state of a pty is reset on first open so that
1862 * settings don't persist across reuse.
1864 * Locking: tty_mutex protects tty, get_tty_driver and tty_init_dev work.
1865 * tty->count should protect the rest.
1866 * ->siglock protects ->signal/->sighand
1869 static int __tty_open(struct inode *inode, struct file *filp)
1871 struct tty_struct *tty;
1873 struct tty_driver *driver;
1875 dev_t device = inode->i_rdev;
1876 unsigned short saved_flags = filp->f_flags;
1878 nonseekable_open(inode, filp);
1881 noctty = filp->f_flags & O_NOCTTY;
1885 mutex_lock(&tty_mutex);
1887 if (device == MKDEV(TTYAUX_MAJOR, 0)) {
1888 tty = get_current_tty();
1890 mutex_unlock(&tty_mutex);
1893 driver = tty_driver_kref_get(tty->driver);
1895 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1897 /* FIXME: Should we take a driver reference ? */
1902 if (device == MKDEV(TTY_MAJOR, 0)) {
1903 extern struct tty_driver *console_driver;
1904 driver = tty_driver_kref_get(console_driver);
1910 if (device == MKDEV(TTYAUX_MAJOR, 1)) {
1911 driver = tty_driver_kref_get(console_device(&index));
1913 /* Don't let /dev/console block */
1914 filp->f_flags |= O_NONBLOCK;
1918 mutex_unlock(&tty_mutex);
1922 driver = get_tty_driver(device, &index);
1924 mutex_unlock(&tty_mutex);
1928 retval = tty_init_dev(driver, index, &tty, 0);
1929 mutex_unlock(&tty_mutex);
1930 tty_driver_kref_put(driver);
1934 filp->private_data = tty;
1935 file_move(filp, &tty->tty_files);
1936 check_tty_count(tty, "tty_open");
1937 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1938 tty->driver->subtype == PTY_TYPE_MASTER)
1940 #ifdef TTY_DEBUG_HANGUP
1941 printk(KERN_DEBUG "opening %s...", tty->name);
1945 retval = tty->ops->open(tty, filp);
1949 filp->f_flags = saved_flags;
1951 if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) &&
1952 !capable(CAP_SYS_ADMIN))
1956 #ifdef TTY_DEBUG_HANGUP
1957 printk(KERN_DEBUG "error %d in opening %s...", retval,
1960 tty_release_dev(filp);
1961 if (retval != -ERESTARTSYS)
1963 if (signal_pending(current))
1967 * Need to reset f_op in case a hangup happened.
1969 if (filp->f_op == &hung_up_tty_fops)
1970 filp->f_op = &tty_fops;
1974 mutex_lock(&tty_mutex);
1975 spin_lock_irq(¤t->sighand->siglock);
1977 current->signal->leader &&
1978 !current->signal->tty &&
1979 tty->session == NULL)
1980 __proc_set_tty(current, tty);
1981 spin_unlock_irq(¤t->sighand->siglock);
1982 mutex_unlock(&tty_mutex);
1986 /* BKL pushdown: scary code avoidance wrapper */
1987 static int tty_open(struct inode *inode, struct file *filp)
1992 ret = __tty_open(inode, filp);
2001 * tty_release - vfs callback for close
2002 * @inode: inode of tty
2003 * @filp: file pointer for handle to tty
2005 * Called the last time each file handle is closed that references
2006 * this tty. There may however be several such references.
2009 * Takes bkl. See tty_release_dev
2012 static int tty_release(struct inode *inode, struct file *filp)
2015 tty_release_dev(filp);
2021 * tty_poll - check tty status
2022 * @filp: file being polled
2023 * @wait: poll wait structures to update
2025 * Call the line discipline polling method to obtain the poll
2026 * status of the device.
2028 * Locking: locks called line discipline but ldisc poll method
2029 * may be re-entered freely by other callers.
2032 static unsigned int tty_poll(struct file *filp, poll_table *wait)
2034 struct tty_struct *tty;
2035 struct tty_ldisc *ld;
2038 tty = (struct tty_struct *)filp->private_data;
2039 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_poll"))
2042 ld = tty_ldisc_ref_wait(tty);
2044 ret = (ld->ops->poll)(tty, filp, wait);
2045 tty_ldisc_deref(ld);
2049 static int tty_fasync(int fd, struct file *filp, int on)
2051 struct tty_struct *tty;
2052 unsigned long flags;
2056 tty = (struct tty_struct *)filp->private_data;
2057 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_fasync"))
2060 retval = fasync_helper(fd, filp, on, &tty->fasync);
2067 if (!waitqueue_active(&tty->read_wait))
2068 tty->minimum_to_wake = 1;
2069 spin_lock_irqsave(&tty->ctrl_lock, flags);
2072 type = PIDTYPE_PGID;
2074 pid = task_pid(current);
2077 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2078 retval = __f_setown(filp, pid, type, 0);
2082 if (!tty->fasync && !waitqueue_active(&tty->read_wait))
2083 tty->minimum_to_wake = N_TTY_BUF_SIZE;
2092 * tiocsti - fake input character
2093 * @tty: tty to fake input into
2094 * @p: pointer to character
2096 * Fake input to a tty device. Does the necessary locking and
2099 * FIXME: does not honour flow control ??
2102 * Called functions take tty_ldisc_lock
2103 * current->signal->tty check is safe without locks
2105 * FIXME: may race normal receive processing
2108 static int tiocsti(struct tty_struct *tty, char __user *p)
2111 struct tty_ldisc *ld;
2113 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2115 if (get_user(ch, p))
2117 ld = tty_ldisc_ref_wait(tty);
2118 ld->ops->receive_buf(tty, &ch, &mbz, 1);
2119 tty_ldisc_deref(ld);
2124 * tiocgwinsz - implement window query ioctl
2126 * @arg: user buffer for result
2128 * Copies the kernel idea of the window size into the user buffer.
2130 * Locking: tty->termios_mutex is taken to ensure the winsize data
2134 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2138 mutex_lock(&tty->termios_mutex);
2139 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2140 mutex_unlock(&tty->termios_mutex);
2142 return err ? -EFAULT: 0;
2146 * tty_do_resize - resize event
2147 * @tty: tty being resized
2148 * @real_tty: real tty (not the same as tty if using a pty/tty pair)
2149 * @rows: rows (character)
2150 * @cols: cols (character)
2152 * Update the termios variables and send the neccessary signals to
2153 * peform a terminal resize correctly
2156 int tty_do_resize(struct tty_struct *tty, struct tty_struct *real_tty,
2159 struct pid *pgrp, *rpgrp;
2160 unsigned long flags;
2162 /* For a PTY we need to lock the tty side */
2163 mutex_lock(&real_tty->termios_mutex);
2164 if (!memcmp(ws, &real_tty->winsize, sizeof(*ws)))
2166 /* Get the PID values and reference them so we can
2167 avoid holding the tty ctrl lock while sending signals */
2168 spin_lock_irqsave(&tty->ctrl_lock, flags);
2169 pgrp = get_pid(tty->pgrp);
2170 rpgrp = get_pid(real_tty->pgrp);
2171 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2174 kill_pgrp(pgrp, SIGWINCH, 1);
2175 if (rpgrp != pgrp && rpgrp)
2176 kill_pgrp(rpgrp, SIGWINCH, 1);
2182 real_tty->winsize = *ws;
2184 mutex_unlock(&real_tty->termios_mutex);
2189 * tiocswinsz - implement window size set ioctl
2191 * @arg: user buffer for result
2193 * Copies the user idea of the window size to the kernel. Traditionally
2194 * this is just advisory information but for the Linux console it
2195 * actually has driver level meaning and triggers a VC resize.
2198 * Driver dependant. The default do_resize method takes the
2199 * tty termios mutex and ctrl_lock. The console takes its own lock
2200 * then calls into the default method.
2203 static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty,
2204 struct winsize __user *arg)
2206 struct winsize tmp_ws;
2207 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2210 if (tty->ops->resize)
2211 return tty->ops->resize(tty, real_tty, &tmp_ws);
2213 return tty_do_resize(tty, real_tty, &tmp_ws);
2217 * tioccons - allow admin to move logical console
2218 * @file: the file to become console
2220 * Allow the adminstrator to move the redirected console device
2222 * Locking: uses redirect_lock to guard the redirect information
2225 static int tioccons(struct file *file)
2227 if (!capable(CAP_SYS_ADMIN))
2229 if (file->f_op->write == redirected_tty_write) {
2231 spin_lock(&redirect_lock);
2234 spin_unlock(&redirect_lock);
2239 spin_lock(&redirect_lock);
2241 spin_unlock(&redirect_lock);
2246 spin_unlock(&redirect_lock);
2251 * fionbio - non blocking ioctl
2252 * @file: file to set blocking value
2253 * @p: user parameter
2255 * Historical tty interfaces had a blocking control ioctl before
2256 * the generic functionality existed. This piece of history is preserved
2257 * in the expected tty API of posix OS's.
2259 * Locking: none, the open fle handle ensures it won't go away.
2262 static int fionbio(struct file *file, int __user *p)
2266 if (get_user(nonblock, p))
2269 /* file->f_flags is still BKL protected in the fs layer - vomit */
2272 file->f_flags |= O_NONBLOCK;
2274 file->f_flags &= ~O_NONBLOCK;
2280 * tiocsctty - set controlling tty
2281 * @tty: tty structure
2282 * @arg: user argument
2284 * This ioctl is used to manage job control. It permits a session
2285 * leader to set this tty as the controlling tty for the session.
2288 * Takes tty_mutex() to protect tty instance
2289 * Takes tasklist_lock internally to walk sessions
2290 * Takes ->siglock() when updating signal->tty
2293 static int tiocsctty(struct tty_struct *tty, int arg)
2296 if (current->signal->leader && (task_session(current) == tty->session))
2299 mutex_lock(&tty_mutex);
2301 * The process must be a session leader and
2302 * not have a controlling tty already.
2304 if (!current->signal->leader || current->signal->tty) {
2311 * This tty is already the controlling
2312 * tty for another session group!
2314 if (arg == 1 && capable(CAP_SYS_ADMIN)) {
2318 read_lock(&tasklist_lock);
2319 session_clear_tty(tty->session);
2320 read_unlock(&tasklist_lock);
2326 proc_set_tty(current, tty);
2328 mutex_unlock(&tty_mutex);
2333 * tty_get_pgrp - return a ref counted pgrp pid
2336 * Returns a refcounted instance of the pid struct for the process
2337 * group controlling the tty.
2340 struct pid *tty_get_pgrp(struct tty_struct *tty)
2342 unsigned long flags;
2345 spin_lock_irqsave(&tty->ctrl_lock, flags);
2346 pgrp = get_pid(tty->pgrp);
2347 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2351 EXPORT_SYMBOL_GPL(tty_get_pgrp);
2354 * tiocgpgrp - get process group
2355 * @tty: tty passed by user
2356 * @real_tty: tty side of the tty pased by the user if a pty else the tty
2359 * Obtain the process group of the tty. If there is no process group
2362 * Locking: none. Reference to current->signal->tty is safe.
2365 static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2370 * (tty == real_tty) is a cheap way of
2371 * testing if the tty is NOT a master pty.
2373 if (tty == real_tty && current->signal->tty != real_tty)
2375 pid = tty_get_pgrp(real_tty);
2376 ret = put_user(pid_vnr(pid), p);
2382 * tiocspgrp - attempt to set process group
2383 * @tty: tty passed by user
2384 * @real_tty: tty side device matching tty passed by user
2387 * Set the process group of the tty to the session passed. Only
2388 * permitted where the tty session is our session.
2390 * Locking: RCU, ctrl lock
2393 static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2397 int retval = tty_check_change(real_tty);
2398 unsigned long flags;
2404 if (!current->signal->tty ||
2405 (current->signal->tty != real_tty) ||
2406 (real_tty->session != task_session(current)))
2408 if (get_user(pgrp_nr, p))
2413 pgrp = find_vpid(pgrp_nr);
2418 if (session_of_pgrp(pgrp) != task_session(current))
2421 spin_lock_irqsave(&tty->ctrl_lock, flags);
2422 put_pid(real_tty->pgrp);
2423 real_tty->pgrp = get_pid(pgrp);
2424 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2431 * tiocgsid - get session id
2432 * @tty: tty passed by user
2433 * @real_tty: tty side of the tty pased by the user if a pty else the tty
2434 * @p: pointer to returned session id
2436 * Obtain the session id of the tty. If there is no session
2439 * Locking: none. Reference to current->signal->tty is safe.
2442 static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2445 * (tty == real_tty) is a cheap way of
2446 * testing if the tty is NOT a master pty.
2448 if (tty == real_tty && current->signal->tty != real_tty)
2450 if (!real_tty->session)
2452 return put_user(pid_vnr(real_tty->session), p);
2456 * tiocsetd - set line discipline
2458 * @p: pointer to user data
2460 * Set the line discipline according to user request.
2462 * Locking: see tty_set_ldisc, this function is just a helper
2465 static int tiocsetd(struct tty_struct *tty, int __user *p)
2470 if (get_user(ldisc, p))
2474 ret = tty_set_ldisc(tty, ldisc);
2481 * send_break - performed time break
2482 * @tty: device to break on
2483 * @duration: timeout in mS
2485 * Perform a timed break on hardware that lacks its own driver level
2486 * timed break functionality.
2489 * atomic_write_lock serializes
2493 static int send_break(struct tty_struct *tty, unsigned int duration)
2497 if (tty->ops->break_ctl == NULL)
2500 if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2501 retval = tty->ops->break_ctl(tty, duration);
2503 /* Do the work ourselves */
2504 if (tty_write_lock(tty, 0) < 0)
2506 retval = tty->ops->break_ctl(tty, -1);
2509 if (!signal_pending(current))
2510 msleep_interruptible(duration);
2511 retval = tty->ops->break_ctl(tty, 0);
2513 tty_write_unlock(tty);
2514 if (signal_pending(current))
2521 * tty_tiocmget - get modem status
2523 * @file: user file pointer
2524 * @p: pointer to result
2526 * Obtain the modem status bits from the tty driver if the feature
2527 * is supported. Return -EINVAL if it is not available.
2529 * Locking: none (up to the driver)
2532 static int tty_tiocmget(struct tty_struct *tty, struct file *file, int __user *p)
2534 int retval = -EINVAL;
2536 if (tty->ops->tiocmget) {
2537 retval = tty->ops->tiocmget(tty, file);
2540 retval = put_user(retval, p);
2546 * tty_tiocmset - set modem status
2548 * @file: user file pointer
2549 * @cmd: command - clear bits, set bits or set all
2550 * @p: pointer to desired bits
2552 * Set the modem status bits from the tty driver if the feature
2553 * is supported. Return -EINVAL if it is not available.
2555 * Locking: none (up to the driver)
2558 static int tty_tiocmset(struct tty_struct *tty, struct file *file, unsigned int cmd,
2562 unsigned int set, clear, val;
2564 if (tty->ops->tiocmset == NULL)
2567 retval = get_user(val, p);
2583 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2584 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2585 return tty->ops->tiocmset(tty, file, set, clear);
2589 * Split this up, as gcc can choke on it otherwise..
2591 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2593 struct tty_struct *tty, *real_tty;
2594 void __user *p = (void __user *)arg;
2596 struct tty_ldisc *ld;
2597 struct inode *inode = file->f_dentry->d_inode;
2599 tty = (struct tty_struct *)file->private_data;
2600 if (tty_paranoia_check(tty, inode, "tty_ioctl"))
2604 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2605 tty->driver->subtype == PTY_TYPE_MASTER)
2606 real_tty = tty->link;
2610 * Factor out some common prep work
2618 retval = tty_check_change(tty);
2621 if (cmd != TIOCCBRK) {
2622 tty_wait_until_sent(tty, 0);
2623 if (signal_pending(current))
2634 return tiocsti(tty, p);
2636 return tiocgwinsz(real_tty, p);
2638 return tiocswinsz(tty, real_tty, p);
2640 return real_tty != tty ? -EINVAL : tioccons(file);
2642 return fionbio(file, p);
2644 set_bit(TTY_EXCLUSIVE, &tty->flags);
2647 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2650 if (current->signal->tty != tty)
2655 return tiocsctty(tty, arg);
2657 return tiocgpgrp(tty, real_tty, p);
2659 return tiocspgrp(tty, real_tty, p);
2661 return tiocgsid(tty, real_tty, p);
2663 return put_user(tty->ldisc.ops->num, (int __user *)p);
2665 return tiocsetd(tty, p);
2669 case TIOCSBRK: /* Turn break on, unconditionally */
2670 if (tty->ops->break_ctl)
2671 return tty->ops->break_ctl(tty, -1);
2673 case TIOCCBRK: /* Turn break off, unconditionally */
2674 if (tty->ops->break_ctl)
2675 return tty->ops->break_ctl(tty, 0);
2677 case TCSBRK: /* SVID version: non-zero arg --> no break */
2678 /* non-zero arg means wait for all output data
2679 * to be sent (performed above) but don't send break.
2680 * This is used by the tcdrain() termios function.
2683 return send_break(tty, 250);
2685 case TCSBRKP: /* support for POSIX tcsendbreak() */
2686 return send_break(tty, arg ? arg*100 : 250);
2689 return tty_tiocmget(tty, file, p);
2693 return tty_tiocmset(tty, file, cmd, p);
2698 /* flush tty buffer and allow ldisc to process ioctl */
2699 tty_buffer_flush(tty);
2704 if (tty->ops->ioctl) {
2705 retval = (tty->ops->ioctl)(tty, file, cmd, arg);
2706 if (retval != -ENOIOCTLCMD)
2709 ld = tty_ldisc_ref_wait(tty);
2711 if (ld->ops->ioctl) {
2712 retval = ld->ops->ioctl(tty, file, cmd, arg);
2713 if (retval == -ENOIOCTLCMD)
2716 tty_ldisc_deref(ld);
2720 #ifdef CONFIG_COMPAT
2721 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2724 struct inode *inode = file->f_dentry->d_inode;
2725 struct tty_struct *tty = file->private_data;
2726 struct tty_ldisc *ld;
2727 int retval = -ENOIOCTLCMD;
2729 if (tty_paranoia_check(tty, inode, "tty_ioctl"))
2732 if (tty->ops->compat_ioctl) {
2733 retval = (tty->ops->compat_ioctl)(tty, file, cmd, arg);
2734 if (retval != -ENOIOCTLCMD)
2738 ld = tty_ldisc_ref_wait(tty);
2739 if (ld->ops->compat_ioctl)
2740 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
2741 tty_ldisc_deref(ld);
2748 * This implements the "Secure Attention Key" --- the idea is to
2749 * prevent trojan horses by killing all processes associated with this
2750 * tty when the user hits the "Secure Attention Key". Required for
2751 * super-paranoid applications --- see the Orange Book for more details.
2753 * This code could be nicer; ideally it should send a HUP, wait a few
2754 * seconds, then send a INT, and then a KILL signal. But you then
2755 * have to coordinate with the init process, since all processes associated
2756 * with the current tty must be dead before the new getty is allowed
2759 * Now, if it would be correct ;-/ The current code has a nasty hole -
2760 * it doesn't catch files in flight. We may send the descriptor to ourselves
2761 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
2763 * Nasty bug: do_SAK is being called in interrupt context. This can
2764 * deadlock. We punt it up to process context. AKPM - 16Mar2001
2766 void __do_SAK(struct tty_struct *tty)
2771 struct task_struct *g, *p;
2772 struct pid *session;
2775 struct fdtable *fdt;
2779 session = tty->session;
2781 tty_ldisc_flush(tty);
2783 tty_driver_flush_buffer(tty);
2785 read_lock(&tasklist_lock);
2786 /* Kill the entire session */
2787 do_each_pid_task(session, PIDTYPE_SID, p) {
2788 printk(KERN_NOTICE "SAK: killed process %d"
2789 " (%s): task_session_nr(p)==tty->session\n",
2790 task_pid_nr(p), p->comm);
2791 send_sig(SIGKILL, p, 1);
2792 } while_each_pid_task(session, PIDTYPE_SID, p);
2793 /* Now kill any processes that happen to have the
2796 do_each_thread(g, p) {
2797 if (p->signal->tty == tty) {
2798 printk(KERN_NOTICE "SAK: killed process %d"
2799 " (%s): task_session_nr(p)==tty->session\n",
2800 task_pid_nr(p), p->comm);
2801 send_sig(SIGKILL, p, 1);
2807 * We don't take a ref to the file, so we must
2808 * hold ->file_lock instead.
2810 spin_lock(&p->files->file_lock);
2811 fdt = files_fdtable(p->files);
2812 for (i = 0; i < fdt->max_fds; i++) {
2813 filp = fcheck_files(p->files, i);
2816 if (filp->f_op->read == tty_read &&
2817 filp->private_data == tty) {
2818 printk(KERN_NOTICE "SAK: killed process %d"
2819 " (%s): fd#%d opened to the tty\n",
2820 task_pid_nr(p), p->comm, i);
2821 force_sig(SIGKILL, p);
2825 spin_unlock(&p->files->file_lock);
2828 } while_each_thread(g, p);
2829 read_unlock(&tasklist_lock);
2833 static void do_SAK_work(struct work_struct *work)
2835 struct tty_struct *tty =
2836 container_of(work, struct tty_struct, SAK_work);
2841 * The tq handling here is a little racy - tty->SAK_work may already be queued.
2842 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
2843 * the values which we write to it will be identical to the values which it
2844 * already has. --akpm
2846 void do_SAK(struct tty_struct *tty)
2850 schedule_work(&tty->SAK_work);
2853 EXPORT_SYMBOL(do_SAK);
2856 * initialize_tty_struct
2857 * @tty: tty to initialize
2859 * This subroutine initializes a tty structure that has been newly
2862 * Locking: none - tty in question must not be exposed at this point
2865 static void initialize_tty_struct(struct tty_struct *tty)
2867 memset(tty, 0, sizeof(struct tty_struct));
2868 kref_init(&tty->kref);
2869 tty->magic = TTY_MAGIC;
2870 tty_ldisc_init(tty);
2871 tty->session = NULL;
2873 tty->overrun_time = jiffies;
2874 tty->buf.head = tty->buf.tail = NULL;
2875 tty_buffer_init(tty);
2876 mutex_init(&tty->termios_mutex);
2877 init_waitqueue_head(&tty->write_wait);
2878 init_waitqueue_head(&tty->read_wait);
2879 INIT_WORK(&tty->hangup_work, do_tty_hangup);
2880 mutex_init(&tty->atomic_read_lock);
2881 mutex_init(&tty->atomic_write_lock);
2882 spin_lock_init(&tty->read_lock);
2883 spin_lock_init(&tty->ctrl_lock);
2884 INIT_LIST_HEAD(&tty->tty_files);
2885 INIT_WORK(&tty->SAK_work, do_SAK_work);
2889 * tty_put_char - write one character to a tty
2893 * Write one byte to the tty using the provided put_char method
2894 * if present. Returns the number of characters successfully output.
2896 * Note: the specific put_char operation in the driver layer may go
2897 * away soon. Don't call it directly, use this method
2900 int tty_put_char(struct tty_struct *tty, unsigned char ch)
2902 if (tty->ops->put_char)
2903 return tty->ops->put_char(tty, ch);
2904 return tty->ops->write(tty, &ch, 1);
2906 EXPORT_SYMBOL_GPL(tty_put_char);
2908 struct class *tty_class;
2911 * tty_register_device - register a tty device
2912 * @driver: the tty driver that describes the tty device
2913 * @index: the index in the tty driver for this tty device
2914 * @device: a struct device that is associated with this tty device.
2915 * This field is optional, if there is no known struct device
2916 * for this tty device it can be set to NULL safely.
2918 * Returns a pointer to the struct device for this tty device
2919 * (or ERR_PTR(-EFOO) on error).
2921 * This call is required to be made to register an individual tty device
2922 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
2923 * that bit is not set, this function should not be called by a tty
2929 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
2930 struct device *device)
2933 dev_t dev = MKDEV(driver->major, driver->minor_start) + index;
2935 if (index >= driver->num) {
2936 printk(KERN_ERR "Attempt to register invalid tty line number "
2938 return ERR_PTR(-EINVAL);
2941 if (driver->type == TTY_DRIVER_TYPE_PTY)
2942 pty_line_name(driver, index, name);
2944 tty_line_name(driver, index, name);
2946 return device_create_drvdata(tty_class, device, dev, NULL, name);
2948 EXPORT_SYMBOL(tty_register_device);
2951 * tty_unregister_device - unregister a tty device
2952 * @driver: the tty driver that describes the tty device
2953 * @index: the index in the tty driver for this tty device
2955 * If a tty device is registered with a call to tty_register_device() then
2956 * this function must be called when the tty device is gone.
2961 void tty_unregister_device(struct tty_driver *driver, unsigned index)
2963 device_destroy(tty_class,
2964 MKDEV(driver->major, driver->minor_start) + index);
2966 EXPORT_SYMBOL(tty_unregister_device);
2968 struct tty_driver *alloc_tty_driver(int lines)
2970 struct tty_driver *driver;
2972 driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
2974 kref_init(&driver->kref);
2975 driver->magic = TTY_DRIVER_MAGIC;
2976 driver->num = lines;
2977 /* later we'll move allocation of tables here */
2981 EXPORT_SYMBOL(alloc_tty_driver);
2983 static void destruct_tty_driver(struct kref *kref)
2985 struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
2987 struct ktermios *tp;
2990 if (driver->flags & TTY_DRIVER_INSTALLED) {
2992 * Free the termios and termios_locked structures because
2993 * we don't want to get memory leaks when modular tty
2994 * drivers are removed from the kernel.
2996 for (i = 0; i < driver->num; i++) {
2997 tp = driver->termios[i];
2999 driver->termios[i] = NULL;
3002 tp = driver->termios_locked[i];
3004 driver->termios_locked[i] = NULL;
3007 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3008 tty_unregister_device(driver, i);
3011 proc_tty_unregister_driver(driver);
3012 driver->ttys = NULL;
3013 driver->termios = driver->termios_locked = NULL;
3015 cdev_del(&driver->cdev);
3020 void tty_driver_kref_put(struct tty_driver *driver)
3022 kref_put(&driver->kref, destruct_tty_driver);
3024 EXPORT_SYMBOL(tty_driver_kref_put);
3026 void tty_set_operations(struct tty_driver *driver,
3027 const struct tty_operations *op)
3031 EXPORT_SYMBOL(tty_set_operations);
3033 void put_tty_driver(struct tty_driver *d)
3035 tty_driver_kref_put(d);
3037 EXPORT_SYMBOL(put_tty_driver);
3040 * Called by a tty driver to register itself.
3042 int tty_register_driver(struct tty_driver *driver)
3049 if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM) && driver->num) {
3050 p = kzalloc(driver->num * 3 * sizeof(void *), GFP_KERNEL);
3055 if (!driver->major) {
3056 error = alloc_chrdev_region(&dev, driver->minor_start,
3057 driver->num, driver->name);
3059 driver->major = MAJOR(dev);
3060 driver->minor_start = MINOR(dev);
3063 dev = MKDEV(driver->major, driver->minor_start);
3064 error = register_chrdev_region(dev, driver->num, driver->name);
3072 driver->ttys = (struct tty_struct **)p;
3073 driver->termios = (struct ktermios **)(p + driver->num);
3074 driver->termios_locked = (struct ktermios **)
3075 (p + driver->num * 2);
3077 driver->ttys = NULL;
3078 driver->termios = NULL;
3079 driver->termios_locked = NULL;
3082 cdev_init(&driver->cdev, &tty_fops);
3083 driver->cdev.owner = driver->owner;
3084 error = cdev_add(&driver->cdev, dev, driver->num);
3086 unregister_chrdev_region(dev, driver->num);
3087 driver->ttys = NULL;
3088 driver->termios = driver->termios_locked = NULL;
3093 mutex_lock(&tty_mutex);
3094 list_add(&driver->tty_drivers, &tty_drivers);
3095 mutex_unlock(&tty_mutex);
3097 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
3098 for (i = 0; i < driver->num; i++)
3099 tty_register_device(driver, i, NULL);
3101 proc_tty_register_driver(driver);
3102 driver->flags |= TTY_DRIVER_INSTALLED;
3106 EXPORT_SYMBOL(tty_register_driver);
3109 * Called by a tty driver to unregister itself.
3111 int tty_unregister_driver(struct tty_driver *driver)
3115 if (driver->refcount)
3118 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3120 mutex_lock(&tty_mutex);
3121 list_del(&driver->tty_drivers);
3122 mutex_unlock(&tty_mutex);
3126 EXPORT_SYMBOL(tty_unregister_driver);
3128 dev_t tty_devnum(struct tty_struct *tty)
3130 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3132 EXPORT_SYMBOL(tty_devnum);
3134 void proc_clear_tty(struct task_struct *p)
3136 struct tty_struct *tty;
3137 spin_lock_irq(&p->sighand->siglock);
3138 tty = p->signal->tty;
3139 p->signal->tty = NULL;
3140 spin_unlock_irq(&p->sighand->siglock);
3144 /* Called under the sighand lock */
3146 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3149 unsigned long flags;
3150 /* We should not have a session or pgrp to put here but.... */
3151 spin_lock_irqsave(&tty->ctrl_lock, flags);
3152 put_pid(tty->session);
3154 tty->pgrp = get_pid(task_pgrp(tsk));
3155 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
3156 tty->session = get_pid(task_session(tsk));
3157 if (tsk->signal->tty) {
3158 printk(KERN_DEBUG "tty not NULL!!\n");
3159 tty_kref_put(tsk->signal->tty);
3162 put_pid(tsk->signal->tty_old_pgrp);
3163 tsk->signal->tty = tty_kref_get(tty);
3164 tsk->signal->tty_old_pgrp = NULL;
3167 static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3169 spin_lock_irq(&tsk->sighand->siglock);
3170 __proc_set_tty(tsk, tty);
3171 spin_unlock_irq(&tsk->sighand->siglock);
3174 struct tty_struct *get_current_tty(void)
3176 struct tty_struct *tty;
3177 unsigned long flags;
3179 spin_lock_irqsave(¤t->sighand->siglock, flags);
3180 tty = tty_kref_get(current->signal->tty);
3181 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
3184 EXPORT_SYMBOL_GPL(get_current_tty);
3186 void tty_default_fops(struct file_operations *fops)
3192 * Initialize the console device. This is called *early*, so
3193 * we can't necessarily depend on lots of kernel help here.
3194 * Just do some early initializations, and do the complex setup
3197 void __init console_init(void)
3201 /* Setup the default TTY line discipline. */
3205 * set up the console device so that later boot sequences can
3206 * inform about problems etc..
3208 call = __con_initcall_start;
3209 while (call < __con_initcall_end) {
3215 static int __init tty_class_init(void)
3217 tty_class = class_create(THIS_MODULE, "tty");
3218 if (IS_ERR(tty_class))
3219 return PTR_ERR(tty_class);
3223 postcore_initcall(tty_class_init);
3225 /* 3/2004 jmc: why do these devices exist? */
3227 static struct cdev tty_cdev, console_cdev;
3230 * Ok, now we can initialize the rest of the tty devices and can count
3231 * on memory allocations, interrupts etc..
3233 static int __init tty_init(void)
3235 cdev_init(&tty_cdev, &tty_fops);
3236 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3237 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3238 panic("Couldn't register /dev/tty driver\n");
3239 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL,
3242 cdev_init(&console_cdev, &console_fops);
3243 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3244 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3245 panic("Couldn't register /dev/console driver\n");
3246 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 1), NULL,
3250 vty_init(&console_fops);
3254 module_init(tty_init);