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 init_dev and 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 #ifdef CONFIG_UNIX98_PTYS
140 extern struct tty_driver *ptm_driver; /* Unix98 pty masters; for /dev/ptmx */
141 static int ptmx_open(struct inode *, struct file *);
144 static void initialize_tty_struct(struct tty_struct *tty);
146 static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
147 static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
148 ssize_t redirected_tty_write(struct file *, const char __user *,
150 static unsigned int tty_poll(struct file *, poll_table *);
151 static int tty_open(struct inode *, struct file *);
152 static int tty_release(struct inode *, struct file *);
153 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
155 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
158 #define tty_compat_ioctl NULL
160 static int tty_fasync(int fd, struct file *filp, int on);
161 static void release_tty(struct tty_struct *tty, int idx);
162 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
163 static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
166 * alloc_tty_struct - allocate a tty object
168 * Return a new empty tty structure. The data fields have not
169 * been initialized in any way but has been zeroed
174 static struct tty_struct *alloc_tty_struct(void)
176 return kzalloc(sizeof(struct tty_struct), GFP_KERNEL);
180 * free_tty_struct - free a disused tty
181 * @tty: tty struct to free
183 * Free the write buffers, tty queue and tty memory itself.
185 * Locking: none. Must be called after tty is definitely unused
188 static inline void free_tty_struct(struct tty_struct *tty)
190 kfree(tty->write_buf);
191 tty_buffer_free_all(tty);
195 #define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base)
198 * tty_name - return tty naming
199 * @tty: tty structure
200 * @buf: buffer for output
202 * Convert a tty structure into a name. The name reflects the kernel
203 * naming policy and if udev is in use may not reflect user space
208 char *tty_name(struct tty_struct *tty, char *buf)
210 if (!tty) /* Hmm. NULL pointer. That's fun. */
211 strcpy(buf, "NULL tty");
213 strcpy(buf, tty->name);
217 EXPORT_SYMBOL(tty_name);
219 int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
222 #ifdef TTY_PARANOIA_CHECK
225 "null TTY for (%d:%d) in %s\n",
226 imajor(inode), iminor(inode), routine);
229 if (tty->magic != TTY_MAGIC) {
231 "bad magic number for tty struct (%d:%d) in %s\n",
232 imajor(inode), iminor(inode), routine);
239 static int check_tty_count(struct tty_struct *tty, const char *routine)
241 #ifdef CHECK_TTY_COUNT
246 list_for_each(p, &tty->tty_files) {
250 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
251 tty->driver->subtype == PTY_TYPE_SLAVE &&
252 tty->link && tty->link->count)
254 if (tty->count != count) {
255 printk(KERN_WARNING "Warning: dev (%s) tty->count(%d) "
256 "!= #fd's(%d) in %s\n",
257 tty->name, tty->count, count, routine);
265 * get_tty_driver - find device of a tty
266 * @dev_t: device identifier
267 * @index: returns the index of the tty
269 * This routine returns a tty driver structure, given a device number
270 * and also passes back the index number.
272 * Locking: caller must hold tty_mutex
275 static struct tty_driver *get_tty_driver(dev_t device, int *index)
277 struct tty_driver *p;
279 list_for_each_entry(p, &tty_drivers, tty_drivers) {
280 dev_t base = MKDEV(p->major, p->minor_start);
281 if (device < base || device >= base + p->num)
283 *index = device - base;
289 #ifdef CONFIG_CONSOLE_POLL
292 * tty_find_polling_driver - find device of a polled tty
293 * @name: name string to match
294 * @line: pointer to resulting tty line nr
296 * This routine returns a tty driver structure, given a name
297 * and the condition that the tty driver is capable of polled
300 struct tty_driver *tty_find_polling_driver(char *name, int *line)
302 struct tty_driver *p, *res = NULL;
307 for (str = name; *str; str++)
308 if ((*str >= '0' && *str <= '9') || *str == ',')
314 tty_line = simple_strtoul(str, &str, 10);
316 mutex_lock(&tty_mutex);
317 /* Search through the tty devices to look for a match */
318 list_for_each_entry(p, &tty_drivers, tty_drivers) {
319 if (strncmp(name, p->name, len) != 0)
326 if (tty_line >= 0 && tty_line <= p->num && p->ops &&
327 p->ops->poll_init && !p->ops->poll_init(p, tty_line, str)) {
333 mutex_unlock(&tty_mutex);
337 EXPORT_SYMBOL_GPL(tty_find_polling_driver);
341 * tty_check_change - check for POSIX terminal changes
344 * If we try to write to, or set the state of, a terminal and we're
345 * not in the foreground, send a SIGTTOU. If the signal is blocked or
346 * ignored, go ahead and perform the operation. (POSIX 7.2)
351 int tty_check_change(struct tty_struct *tty)
356 if (current->signal->tty != tty)
359 spin_lock_irqsave(&tty->ctrl_lock, flags);
362 printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");
365 if (task_pgrp(current) == tty->pgrp)
367 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
368 if (is_ignored(SIGTTOU))
370 if (is_current_pgrp_orphaned()) {
374 kill_pgrp(task_pgrp(current), SIGTTOU, 1);
375 set_thread_flag(TIF_SIGPENDING);
380 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
384 EXPORT_SYMBOL(tty_check_change);
386 static ssize_t hung_up_tty_read(struct file *file, char __user *buf,
387 size_t count, loff_t *ppos)
392 static ssize_t hung_up_tty_write(struct file *file, const char __user *buf,
393 size_t count, loff_t *ppos)
398 /* No kernel lock held - none needed ;) */
399 static unsigned int hung_up_tty_poll(struct file *filp, poll_table *wait)
401 return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM;
404 static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
407 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
410 static long hung_up_tty_compat_ioctl(struct file *file,
411 unsigned int cmd, unsigned long arg)
413 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
416 static const struct file_operations tty_fops = {
421 .unlocked_ioctl = tty_ioctl,
422 .compat_ioctl = tty_compat_ioctl,
424 .release = tty_release,
425 .fasync = tty_fasync,
428 #ifdef CONFIG_UNIX98_PTYS
429 static const struct file_operations ptmx_fops = {
434 .unlocked_ioctl = tty_ioctl,
435 .compat_ioctl = tty_compat_ioctl,
437 .release = tty_release,
438 .fasync = tty_fasync,
442 static const struct file_operations console_fops = {
445 .write = redirected_tty_write,
447 .unlocked_ioctl = tty_ioctl,
448 .compat_ioctl = tty_compat_ioctl,
450 .release = tty_release,
451 .fasync = tty_fasync,
454 static const struct file_operations hung_up_tty_fops = {
456 .read = hung_up_tty_read,
457 .write = hung_up_tty_write,
458 .poll = hung_up_tty_poll,
459 .unlocked_ioctl = hung_up_tty_ioctl,
460 .compat_ioctl = hung_up_tty_compat_ioctl,
461 .release = tty_release,
464 static DEFINE_SPINLOCK(redirect_lock);
465 static struct file *redirect;
468 * tty_wakeup - request more data
471 * Internal and external helper for wakeups of tty. This function
472 * informs the line discipline if present that the driver is ready
473 * to receive more output data.
476 void tty_wakeup(struct tty_struct *tty)
478 struct tty_ldisc *ld;
480 if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
481 ld = tty_ldisc_ref(tty);
483 if (ld->ops->write_wakeup)
484 ld->ops->write_wakeup(tty);
488 wake_up_interruptible(&tty->write_wait);
491 EXPORT_SYMBOL_GPL(tty_wakeup);
494 * tty_ldisc_flush - flush line discipline queue
497 * Flush the line discipline queue (if any) for this tty. If there
498 * is no line discipline active this is a no-op.
501 void tty_ldisc_flush(struct tty_struct *tty)
503 struct tty_ldisc *ld = tty_ldisc_ref(tty);
505 if (ld->ops->flush_buffer)
506 ld->ops->flush_buffer(tty);
509 tty_buffer_flush(tty);
512 EXPORT_SYMBOL_GPL(tty_ldisc_flush);
515 * tty_reset_termios - reset terminal state
518 * Restore a terminal to the driver default state
521 static void tty_reset_termios(struct tty_struct *tty)
523 mutex_lock(&tty->termios_mutex);
524 *tty->termios = tty->driver->init_termios;
525 tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
526 tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
527 mutex_unlock(&tty->termios_mutex);
531 * do_tty_hangup - actual handler for hangup events
534 * This can be called by the "eventd" kernel thread. That is process
535 * synchronous but doesn't hold any locks, so we need to make sure we
536 * have the appropriate locks for what we're doing.
538 * The hangup event clears any pending redirections onto the hung up
539 * device. It ensures future writes will error and it does the needed
540 * line discipline hangup and signal delivery. The tty object itself
545 * redirect lock for undoing redirection
546 * file list lock for manipulating list of ttys
547 * tty_ldisc_lock from called functions
548 * termios_mutex resetting termios data
549 * tasklist_lock to walk task list for hangup event
550 * ->siglock to protect ->signal/->sighand
552 static void do_tty_hangup(struct work_struct *work)
554 struct tty_struct *tty =
555 container_of(work, struct tty_struct, hangup_work);
556 struct file *cons_filp = NULL;
557 struct file *filp, *f = NULL;
558 struct task_struct *p;
559 struct tty_ldisc *ld;
560 int closecount = 0, n;
567 /* inuse_filps is protected by the single kernel lock */
570 spin_lock(&redirect_lock);
571 if (redirect && redirect->private_data == tty) {
575 spin_unlock(&redirect_lock);
577 check_tty_count(tty, "do_tty_hangup");
579 /* This breaks for file handles being sent over AF_UNIX sockets ? */
580 list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) {
581 if (filp->f_op->write == redirected_tty_write)
583 if (filp->f_op->write != tty_write)
586 tty_fasync(-1, filp, 0); /* can't block */
587 filp->f_op = &hung_up_tty_fops;
591 * FIXME! What are the locking issues here? This may me overdoing
592 * things... This question is especially important now that we've
593 * removed the irqlock.
595 ld = tty_ldisc_ref(tty);
597 /* We may have no line discipline at this point */
598 if (ld->ops->flush_buffer)
599 ld->ops->flush_buffer(tty);
600 tty_driver_flush_buffer(tty);
601 if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) &&
602 ld->ops->write_wakeup)
603 ld->ops->write_wakeup(tty);
605 ld->ops->hangup(tty);
608 * FIXME: Once we trust the LDISC code better we can wait here for
609 * ldisc completion and fix the driver call race
611 wake_up_interruptible(&tty->write_wait);
612 wake_up_interruptible(&tty->read_wait);
614 * Shutdown the current line discipline, and reset it to
617 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
618 tty_reset_termios(tty);
619 /* Defer ldisc switch */
620 /* tty_deferred_ldisc_switch(N_TTY);
622 This should get done automatically when the port closes and
623 tty_release is called */
625 read_lock(&tasklist_lock);
627 do_each_pid_task(tty->session, PIDTYPE_SID, p) {
628 spin_lock_irq(&p->sighand->siglock);
629 if (p->signal->tty == tty) {
630 p->signal->tty = NULL;
631 /* We defer the dereferences outside fo
635 if (!p->signal->leader) {
636 spin_unlock_irq(&p->sighand->siglock);
639 __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
640 __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
641 put_pid(p->signal->tty_old_pgrp); /* A noop */
642 spin_lock_irqsave(&tty->ctrl_lock, flags);
644 p->signal->tty_old_pgrp = get_pid(tty->pgrp);
645 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
646 spin_unlock_irq(&p->sighand->siglock);
647 } while_each_pid_task(tty->session, PIDTYPE_SID, p);
649 read_unlock(&tasklist_lock);
651 spin_lock_irqsave(&tty->ctrl_lock, flags);
653 put_pid(tty->session);
657 tty->ctrl_status = 0;
658 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
660 /* Account for the p->signal references we killed */
665 * If one of the devices matches a console pointer, we
666 * cannot just call hangup() because that will cause
667 * tty->count and state->count to go out of sync.
668 * So we just call close() the right number of times.
672 for (n = 0; n < closecount; n++)
673 tty->ops->close(tty, cons_filp);
674 } else if (tty->ops->hangup)
675 (tty->ops->hangup)(tty);
677 * We don't want to have driver/ldisc interactions beyond
678 * the ones we did here. The driver layer expects no
679 * calls after ->hangup() from the ldisc side. However we
680 * can't yet guarantee all that.
682 set_bit(TTY_HUPPED, &tty->flags);
684 tty_ldisc_enable(tty);
693 * tty_hangup - trigger a hangup event
694 * @tty: tty to hangup
696 * A carrier loss (virtual or otherwise) has occurred on this like
697 * schedule a hangup sequence to run after this event.
700 void tty_hangup(struct tty_struct *tty)
702 #ifdef TTY_DEBUG_HANGUP
704 printk(KERN_DEBUG "%s hangup...\n", tty_name(tty, buf));
706 schedule_work(&tty->hangup_work);
709 EXPORT_SYMBOL(tty_hangup);
712 * tty_vhangup - process vhangup
713 * @tty: tty to hangup
715 * The user has asked via system call for the terminal to be hung up.
716 * We do this synchronously so that when the syscall returns the process
717 * is complete. That guarantee is necessary for security reasons.
720 void tty_vhangup(struct tty_struct *tty)
722 #ifdef TTY_DEBUG_HANGUP
725 printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf));
727 do_tty_hangup(&tty->hangup_work);
730 EXPORT_SYMBOL(tty_vhangup);
733 * tty_hung_up_p - was tty hung up
734 * @filp: file pointer of tty
736 * Return true if the tty has been subject to a vhangup or a carrier
740 int tty_hung_up_p(struct file *filp)
742 return (filp->f_op == &hung_up_tty_fops);
745 EXPORT_SYMBOL(tty_hung_up_p);
747 static void session_clear_tty(struct pid *session)
749 struct task_struct *p;
750 do_each_pid_task(session, PIDTYPE_SID, p) {
752 } while_each_pid_task(session, PIDTYPE_SID, p);
756 * disassociate_ctty - disconnect controlling tty
757 * @on_exit: true if exiting so need to "hang up" the session
759 * This function is typically called only by the session leader, when
760 * it wants to disassociate itself from its controlling tty.
762 * It performs the following functions:
763 * (1) Sends a SIGHUP and SIGCONT to the foreground process group
764 * (2) Clears the tty from being controlling the session
765 * (3) Clears the controlling tty for all processes in the
768 * The argument on_exit is set to 1 if called when a process is
769 * exiting; it is 0 if called by the ioctl TIOCNOTTY.
772 * BKL is taken for hysterical raisins
773 * tty_mutex is taken to protect tty
774 * ->siglock is taken to protect ->signal/->sighand
775 * tasklist_lock is taken to walk process list for sessions
776 * ->siglock is taken to protect ->signal/->sighand
779 void disassociate_ctty(int on_exit)
781 struct tty_struct *tty;
782 struct pid *tty_pgrp = NULL;
785 mutex_lock(&tty_mutex);
786 tty = get_current_tty();
788 tty_pgrp = get_pid(tty->pgrp);
790 mutex_unlock(&tty_mutex);
791 /* XXX: here we race, there is nothing protecting tty */
792 if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)
795 } else if (on_exit) {
796 struct pid *old_pgrp;
797 spin_lock_irq(¤t->sighand->siglock);
798 old_pgrp = current->signal->tty_old_pgrp;
799 current->signal->tty_old_pgrp = NULL;
800 spin_unlock_irq(¤t->sighand->siglock);
802 kill_pgrp(old_pgrp, SIGHUP, on_exit);
803 kill_pgrp(old_pgrp, SIGCONT, on_exit);
806 mutex_unlock(&tty_mutex);
810 kill_pgrp(tty_pgrp, SIGHUP, on_exit);
812 kill_pgrp(tty_pgrp, SIGCONT, on_exit);
816 spin_lock_irq(¤t->sighand->siglock);
817 put_pid(current->signal->tty_old_pgrp);
818 current->signal->tty_old_pgrp = NULL;
819 spin_unlock_irq(¤t->sighand->siglock);
821 mutex_lock(&tty_mutex);
822 /* It is possible that do_tty_hangup has free'd this tty */
823 tty = get_current_tty();
826 spin_lock_irqsave(&tty->ctrl_lock, flags);
827 put_pid(tty->session);
831 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
833 #ifdef TTY_DEBUG_HANGUP
834 printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
838 mutex_unlock(&tty_mutex);
840 /* Now clear signal->tty under the lock */
841 read_lock(&tasklist_lock);
842 session_clear_tty(task_session(current));
843 read_unlock(&tasklist_lock);
848 * no_tty - Ensure the current process does not have a controlling tty
852 struct task_struct *tsk = current;
854 if (tsk->signal->leader)
855 disassociate_ctty(0);
862 * stop_tty - propagate flow control
865 * Perform flow control to the driver. For PTY/TTY pairs we
866 * must also propagate the TIOCKPKT status. May be called
867 * on an already stopped device and will not re-call the driver
870 * This functionality is used by both the line disciplines for
871 * halting incoming flow and by the driver. It may therefore be
872 * called from any context, may be under the tty atomic_write_lock
876 * Uses the tty control lock internally
879 void stop_tty(struct tty_struct *tty)
882 spin_lock_irqsave(&tty->ctrl_lock, flags);
884 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
888 if (tty->link && tty->link->packet) {
889 tty->ctrl_status &= ~TIOCPKT_START;
890 tty->ctrl_status |= TIOCPKT_STOP;
891 wake_up_interruptible(&tty->link->read_wait);
893 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
895 (tty->ops->stop)(tty);
898 EXPORT_SYMBOL(stop_tty);
901 * start_tty - propagate flow control
904 * Start a tty that has been stopped if at all possible. Perform
905 * any necessary wakeups and propagate the TIOCPKT status. If this
906 * is the tty was previous stopped and is being started then the
907 * driver start method is invoked and the line discipline woken.
913 void start_tty(struct tty_struct *tty)
916 spin_lock_irqsave(&tty->ctrl_lock, flags);
917 if (!tty->stopped || tty->flow_stopped) {
918 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
922 if (tty->link && tty->link->packet) {
923 tty->ctrl_status &= ~TIOCPKT_STOP;
924 tty->ctrl_status |= TIOCPKT_START;
925 wake_up_interruptible(&tty->link->read_wait);
927 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
929 (tty->ops->start)(tty);
930 /* If we have a running line discipline it may need kicking */
934 EXPORT_SYMBOL(start_tty);
937 * tty_read - read method for tty device files
938 * @file: pointer to tty file
940 * @count: size of user buffer
943 * Perform the read system call function on this terminal device. Checks
944 * for hung up devices before calling the line discipline method.
947 * Locks the line discipline internally while needed. Multiple
948 * read calls may be outstanding in parallel.
951 static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
955 struct tty_struct *tty;
957 struct tty_ldisc *ld;
959 tty = (struct tty_struct *)file->private_data;
960 inode = file->f_path.dentry->d_inode;
961 if (tty_paranoia_check(tty, inode, "tty_read"))
963 if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags)))
966 /* We want to wait for the line discipline to sort out in this
968 ld = tty_ldisc_ref_wait(tty);
970 i = (ld->ops->read)(tty, file, buf, count);
975 inode->i_atime = current_fs_time(inode->i_sb);
979 void tty_write_unlock(struct tty_struct *tty)
981 mutex_unlock(&tty->atomic_write_lock);
982 wake_up_interruptible(&tty->write_wait);
985 int tty_write_lock(struct tty_struct *tty, int ndelay)
987 if (!mutex_trylock(&tty->atomic_write_lock)) {
990 if (mutex_lock_interruptible(&tty->atomic_write_lock))
997 * Split writes up in sane blocksizes to avoid
998 * denial-of-service type attacks
1000 static inline ssize_t do_tty_write(
1001 ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
1002 struct tty_struct *tty,
1004 const char __user *buf,
1007 ssize_t ret, written = 0;
1010 ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
1015 * We chunk up writes into a temporary buffer. This
1016 * simplifies low-level drivers immensely, since they
1017 * don't have locking issues and user mode accesses.
1019 * But if TTY_NO_WRITE_SPLIT is set, we should use a
1022 * The default chunk-size is 2kB, because the NTTY
1023 * layer has problems with bigger chunks. It will
1024 * claim to be able to handle more characters than
1027 * FIXME: This can probably go away now except that 64K chunks
1028 * are too likely to fail unless switched to vmalloc...
1031 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
1036 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
1037 if (tty->write_cnt < chunk) {
1043 buf = kmalloc(chunk, GFP_KERNEL);
1048 kfree(tty->write_buf);
1049 tty->write_cnt = chunk;
1050 tty->write_buf = buf;
1053 /* Do the write .. */
1055 size_t size = count;
1059 if (copy_from_user(tty->write_buf, buf, size))
1061 ret = write(tty, file, tty->write_buf, size);
1070 if (signal_pending(current))
1075 struct inode *inode = file->f_path.dentry->d_inode;
1076 inode->i_mtime = current_fs_time(inode->i_sb);
1080 tty_write_unlock(tty);
1086 * tty_write - write method for tty device file
1087 * @file: tty file pointer
1088 * @buf: user data to write
1089 * @count: bytes to write
1092 * Write data to a tty device via the line discipline.
1095 * Locks the line discipline as required
1096 * Writes to the tty driver are serialized by the atomic_write_lock
1097 * and are then processed in chunks to the device. The line discipline
1098 * write method will not be involked in parallel for each device
1099 * The line discipline write method is called under the big
1100 * kernel lock for historical reasons. New code should not rely on this.
1103 static ssize_t tty_write(struct file *file, const char __user *buf,
1104 size_t count, loff_t *ppos)
1106 struct tty_struct *tty;
1107 struct inode *inode = file->f_path.dentry->d_inode;
1109 struct tty_ldisc *ld;
1111 tty = (struct tty_struct *)file->private_data;
1112 if (tty_paranoia_check(tty, inode, "tty_write"))
1114 if (!tty || !tty->ops->write ||
1115 (test_bit(TTY_IO_ERROR, &tty->flags)))
1117 /* Short term debug to catch buggy drivers */
1118 if (tty->ops->write_room == NULL)
1119 printk(KERN_ERR "tty driver %s lacks a write_room method.\n",
1121 ld = tty_ldisc_ref_wait(tty);
1122 if (!ld->ops->write)
1125 ret = do_tty_write(ld->ops->write, tty, file, buf, count);
1126 tty_ldisc_deref(ld);
1130 ssize_t redirected_tty_write(struct file *file, const char __user *buf,
1131 size_t count, loff_t *ppos)
1133 struct file *p = NULL;
1135 spin_lock(&redirect_lock);
1140 spin_unlock(&redirect_lock);
1144 res = vfs_write(p, buf, count, &p->f_pos);
1148 return tty_write(file, buf, count, ppos);
1151 static char ptychar[] = "pqrstuvwxyzabcde";
1154 * pty_line_name - generate name for a pty
1155 * @driver: the tty driver in use
1156 * @index: the minor number
1157 * @p: output buffer of at least 6 bytes
1159 * Generate a name from a driver reference and write it to the output
1164 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1166 int i = index + driver->name_base;
1167 /* ->name is initialized to "ttyp", but "tty" is expected */
1168 sprintf(p, "%s%c%x",
1169 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1170 ptychar[i >> 4 & 0xf], i & 0xf);
1174 * pty_line_name - generate name for a tty
1175 * @driver: the tty driver in use
1176 * @index: the minor number
1177 * @p: output buffer of at least 7 bytes
1179 * Generate a name from a driver reference and write it to the output
1184 static void tty_line_name(struct tty_driver *driver, int index, char *p)
1186 sprintf(p, "%s%d", driver->name, index + driver->name_base);
1190 * init_dev - initialise a tty device
1191 * @driver: tty driver we are opening a device on
1192 * @idx: device index
1193 * @tty: returned tty structure
1195 * Prepare a tty device. This may not be a "new" clean device but
1196 * could also be an active device. The pty drivers require special
1197 * handling because of this.
1200 * The function is called under the tty_mutex, which
1201 * protects us from the tty struct or driver itself going away.
1203 * On exit the tty device has the line discipline attached and
1204 * a reference count of 1. If a pair was created for pty/tty use
1205 * and the other was a pty master then it too has a reference count of 1.
1207 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1208 * failed open. The new code protects the open with a mutex, so it's
1209 * really quite straightforward. The mutex locking can probably be
1210 * relaxed for the (most common) case of reopening a tty.
1213 static int init_dev(struct tty_driver *driver, int idx,
1214 struct tty_struct **ret_tty)
1216 struct tty_struct *tty, *o_tty;
1217 struct ktermios *tp, **tp_loc, *o_tp, **o_tp_loc;
1218 struct ktermios *ltp, **ltp_loc, *o_ltp, **o_ltp_loc;
1221 /* check whether we're reopening an existing tty */
1222 if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
1223 tty = devpts_get_tty(idx);
1225 * If we don't have a tty here on a slave open, it's because
1226 * the master already started the close process and there's
1227 * no relation between devpts file and tty anymore.
1229 if (!tty && driver->subtype == PTY_TYPE_SLAVE) {
1234 * It's safe from now on because init_dev() is called with
1235 * tty_mutex held and release_dev() won't change tty->count
1236 * or tty->flags without having to grab tty_mutex
1238 if (tty && driver->subtype == PTY_TYPE_MASTER)
1241 tty = driver->ttys[idx];
1243 if (tty) goto fast_track;
1246 * First time open is complex, especially for PTY devices.
1247 * This code guarantees that either everything succeeds and the
1248 * TTY is ready for operation, or else the table slots are vacated
1249 * and the allocated memory released. (Except that the termios
1250 * and locked termios may be retained.)
1253 if (!try_module_get(driver->owner)) {
1262 tty = alloc_tty_struct();
1265 initialize_tty_struct(tty);
1266 tty->driver = driver;
1267 tty->ops = driver->ops;
1269 tty_line_name(driver, idx, tty->name);
1271 if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
1272 tp_loc = &tty->termios;
1273 ltp_loc = &tty->termios_locked;
1275 tp_loc = &driver->termios[idx];
1276 ltp_loc = &driver->termios_locked[idx];
1280 tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
1283 *tp = driver->init_termios;
1287 ltp = kzalloc(sizeof(struct ktermios), GFP_KERNEL);
1292 if (driver->type == TTY_DRIVER_TYPE_PTY) {
1293 o_tty = alloc_tty_struct();
1296 initialize_tty_struct(o_tty);
1297 o_tty->driver = driver->other;
1298 o_tty->ops = driver->ops;
1300 tty_line_name(driver->other, idx, o_tty->name);
1302 if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
1303 o_tp_loc = &o_tty->termios;
1304 o_ltp_loc = &o_tty->termios_locked;
1306 o_tp_loc = &driver->other->termios[idx];
1307 o_ltp_loc = &driver->other->termios_locked[idx];
1311 o_tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
1314 *o_tp = driver->other->init_termios;
1318 o_ltp = kzalloc(sizeof(struct ktermios), GFP_KERNEL);
1324 * Everything allocated ... set up the o_tty structure.
1326 if (!(driver->other->flags & TTY_DRIVER_DEVPTS_MEM))
1327 driver->other->ttys[idx] = o_tty;
1332 o_tty->termios = *o_tp_loc;
1333 o_tty->termios_locked = *o_ltp_loc;
1334 driver->other->refcount++;
1335 if (driver->subtype == PTY_TYPE_MASTER)
1338 /* Establish the links in both directions */
1344 * All structures have been allocated, so now we install them.
1345 * Failures after this point use release_tty to clean up, so
1346 * there's no need to null out the local pointers.
1348 if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM))
1349 driver->ttys[idx] = tty;
1355 tty->termios = *tp_loc;
1356 tty->termios_locked = *ltp_loc;
1357 /* Compatibility until drivers always set this */
1358 tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
1359 tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
1364 * Structures all installed ... call the ldisc open routines.
1365 * If we fail here just call release_tty to clean up. No need
1366 * to decrement the use counts, as release_tty doesn't care.
1369 retval = tty_ldisc_setup(tty, o_tty);
1372 goto release_mem_out;
1376 * This fast open can be used if the tty is already open.
1377 * No memory is allocated, and the only failures are from
1378 * attempting to open a closing tty or attempting multiple
1379 * opens on a pty master.
1382 if (test_bit(TTY_CLOSING, &tty->flags)) {
1386 if (driver->type == TTY_DRIVER_TYPE_PTY &&
1387 driver->subtype == PTY_TYPE_MASTER) {
1389 * special case for PTY masters: only one open permitted,
1390 * and the slave side open count is incremented as well.
1399 tty->driver = driver; /* N.B. why do this every time?? */
1402 if (!test_bit(TTY_LDISC, &tty->flags))
1403 printk(KERN_ERR "init_dev but no ldisc\n");
1407 /* All paths come through here to release the mutex */
1411 /* Release locally allocated memory ... nothing placed in slots */
1415 free_tty_struct(o_tty);
1418 free_tty_struct(tty);
1421 module_put(driver->owner);
1425 /* call the tty release_tty routine to clean out this slot */
1427 if (printk_ratelimit())
1428 printk(KERN_INFO "init_dev: ldisc open failed, "
1429 "clearing slot %d\n", idx);
1430 release_tty(tty, idx);
1435 * release_one_tty - release tty structure memory
1436 * @kref: kref of tty we are obliterating
1438 * Releases memory associated with a tty structure, and clears out the
1439 * driver table slots. This function is called when a device is no longer
1440 * in use. It also gets called when setup of a device fails.
1443 * tty_mutex - sometimes only
1444 * takes the file list lock internally when working on the list
1445 * of ttys that the driver keeps.
1447 static void release_one_tty(struct kref *kref)
1449 struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1450 int devpts = tty->driver->flags & TTY_DRIVER_DEVPTS_MEM;
1451 struct ktermios *tp;
1452 int idx = tty->index;
1455 tty->driver->ttys[idx] = NULL;
1457 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
1458 /* FIXME: Locking on ->termios array */
1461 tty->driver->termios[idx] = NULL;
1464 tp = tty->termios_locked;
1466 tty->driver->termios_locked[idx] = NULL;
1472 /* FIXME: locking on tty->driver->refcount */
1473 tty->driver->refcount--;
1476 list_del_init(&tty->tty_files);
1479 free_tty_struct(tty);
1483 * tty_kref_put - release a tty kref
1486 * Release a reference to a tty device and if need be let the kref
1487 * layer destruct the object for us
1490 void tty_kref_put(struct tty_struct *tty)
1493 kref_put(&tty->kref, release_one_tty);
1495 EXPORT_SYMBOL(tty_kref_put);
1498 * release_tty - release tty structure memory
1500 * Release both @tty and a possible linked partner (think pty pair),
1501 * and decrement the refcount of the backing module.
1504 * tty_mutex - sometimes only
1505 * takes the file list lock internally when working on the list
1506 * of ttys that the driver keeps.
1507 * FIXME: should we require tty_mutex is held here ??
1509 * FIXME: We want to defer the module put of the driver to the
1512 static void release_tty(struct tty_struct *tty, int idx)
1514 struct tty_driver *driver = tty->driver;
1516 /* This should always be true but check for the moment */
1517 WARN_ON(tty->index != idx);
1520 tty_kref_put(tty->link);
1522 module_put(driver->owner);
1526 * Even releasing the tty structures is a tricky business.. We have
1527 * to be very careful that the structures are all released at the
1528 * same time, as interrupts might otherwise get the wrong pointers.
1530 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1531 * lead to double frees or releasing memory still in use.
1533 static void release_dev(struct file *filp)
1535 struct tty_struct *tty, *o_tty;
1536 int pty_master, tty_closing, o_tty_closing, do_sleep;
1541 tty = (struct tty_struct *)filp->private_data;
1542 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode,
1546 check_tty_count(tty, "release_dev");
1548 tty_fasync(-1, filp, 0);
1551 pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1552 tty->driver->subtype == PTY_TYPE_MASTER);
1553 devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0;
1556 #ifdef TTY_PARANOIA_CHECK
1557 if (idx < 0 || idx >= tty->driver->num) {
1558 printk(KERN_DEBUG "release_dev: bad idx when trying to "
1559 "free (%s)\n", tty->name);
1562 if (!(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
1563 if (tty != tty->driver->ttys[idx]) {
1564 printk(KERN_DEBUG "release_dev: driver.table[%d] not tty "
1565 "for (%s)\n", idx, tty->name);
1568 if (tty->termios != tty->driver->termios[idx]) {
1569 printk(KERN_DEBUG "release_dev: driver.termios[%d] not termios "
1574 if (tty->termios_locked != tty->driver->termios_locked[idx]) {
1575 printk(KERN_DEBUG "release_dev: driver.termios_locked[%d] not "
1576 "termios_locked for (%s)\n",
1583 #ifdef TTY_DEBUG_HANGUP
1584 printk(KERN_DEBUG "release_dev of %s (tty count=%d)...",
1585 tty_name(tty, buf), tty->count);
1588 #ifdef TTY_PARANOIA_CHECK
1589 if (tty->driver->other &&
1590 !(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
1591 if (o_tty != tty->driver->other->ttys[idx]) {
1592 printk(KERN_DEBUG "release_dev: other->table[%d] "
1593 "not o_tty for (%s)\n",
1597 if (o_tty->termios != tty->driver->other->termios[idx]) {
1598 printk(KERN_DEBUG "release_dev: other->termios[%d] "
1599 "not o_termios for (%s)\n",
1603 if (o_tty->termios_locked !=
1604 tty->driver->other->termios_locked[idx]) {
1605 printk(KERN_DEBUG "release_dev: other->termios_locked["
1606 "%d] not o_termios_locked for (%s)\n",
1610 if (o_tty->link != tty) {
1611 printk(KERN_DEBUG "release_dev: bad pty pointers\n");
1616 if (tty->ops->close)
1617 tty->ops->close(tty, filp);
1620 * Sanity check: if tty->count is going to zero, there shouldn't be
1621 * any waiters on tty->read_wait or tty->write_wait. We test the
1622 * wait queues and kick everyone out _before_ actually starting to
1623 * close. This ensures that we won't block while releasing the tty
1626 * The test for the o_tty closing is necessary, since the master and
1627 * slave sides may close in any order. If the slave side closes out
1628 * first, its count will be one, since the master side holds an open.
1629 * Thus this test wouldn't be triggered at the time the slave closes,
1632 * Note that it's possible for the tty to be opened again while we're
1633 * flushing out waiters. By recalculating the closing flags before
1634 * each iteration we avoid any problems.
1637 /* Guard against races with tty->count changes elsewhere and
1638 opens on /dev/tty */
1640 mutex_lock(&tty_mutex);
1641 tty_closing = tty->count <= 1;
1642 o_tty_closing = o_tty &&
1643 (o_tty->count <= (pty_master ? 1 : 0));
1647 if (waitqueue_active(&tty->read_wait)) {
1648 wake_up(&tty->read_wait);
1651 if (waitqueue_active(&tty->write_wait)) {
1652 wake_up(&tty->write_wait);
1656 if (o_tty_closing) {
1657 if (waitqueue_active(&o_tty->read_wait)) {
1658 wake_up(&o_tty->read_wait);
1661 if (waitqueue_active(&o_tty->write_wait)) {
1662 wake_up(&o_tty->write_wait);
1669 printk(KERN_WARNING "release_dev: %s: read/write wait queue "
1670 "active!\n", tty_name(tty, buf));
1671 mutex_unlock(&tty_mutex);
1676 * The closing flags are now consistent with the open counts on
1677 * both sides, and we've completed the last operation that could
1678 * block, so it's safe to proceed with closing.
1681 if (--o_tty->count < 0) {
1682 printk(KERN_WARNING "release_dev: bad pty slave count "
1684 o_tty->count, tty_name(o_tty, buf));
1688 if (--tty->count < 0) {
1689 printk(KERN_WARNING "release_dev: bad tty->count (%d) for %s\n",
1690 tty->count, tty_name(tty, buf));
1695 * We've decremented tty->count, so we need to remove this file
1696 * descriptor off the tty->tty_files list; this serves two
1698 * - check_tty_count sees the correct number of file descriptors
1699 * associated with this tty.
1700 * - do_tty_hangup no longer sees this file descriptor as
1701 * something that needs to be handled for hangups.
1704 filp->private_data = NULL;
1707 * Perform some housekeeping before deciding whether to return.
1709 * Set the TTY_CLOSING flag if this was the last open. In the
1710 * case of a pty we may have to wait around for the other side
1711 * to close, and TTY_CLOSING makes sure we can't be reopened.
1714 set_bit(TTY_CLOSING, &tty->flags);
1716 set_bit(TTY_CLOSING, &o_tty->flags);
1719 * If _either_ side is closing, make sure there aren't any
1720 * processes that still think tty or o_tty is their controlling
1723 if (tty_closing || o_tty_closing) {
1724 read_lock(&tasklist_lock);
1725 session_clear_tty(tty->session);
1727 session_clear_tty(o_tty->session);
1728 read_unlock(&tasklist_lock);
1731 mutex_unlock(&tty_mutex);
1733 /* check whether both sides are closing ... */
1734 if (!tty_closing || (o_tty && !o_tty_closing))
1737 #ifdef TTY_DEBUG_HANGUP
1738 printk(KERN_DEBUG "freeing tty structure...");
1741 * Ask the line discipline code to release its structures
1743 tty_ldisc_release(tty, o_tty);
1745 * The release_tty function takes care of the details of clearing
1746 * the slots and preserving the termios structure.
1748 release_tty(tty, idx);
1750 /* Make this pty number available for reallocation */
1752 devpts_kill_index(idx);
1756 * tty_open - open a tty device
1757 * @inode: inode of device file
1758 * @filp: file pointer to tty
1760 * tty_open and tty_release keep up the tty count that contains the
1761 * number of opens done on a tty. We cannot use the inode-count, as
1762 * different inodes might point to the same tty.
1764 * Open-counting is needed for pty masters, as well as for keeping
1765 * track of serial lines: DTR is dropped when the last close happens.
1766 * (This is not done solely through tty->count, now. - Ted 1/27/92)
1768 * The termios state of a pty is reset on first open so that
1769 * settings don't persist across reuse.
1771 * Locking: tty_mutex protects tty, get_tty_driver and init_dev work.
1772 * tty->count should protect the rest.
1773 * ->siglock protects ->signal/->sighand
1776 static int __tty_open(struct inode *inode, struct file *filp)
1778 struct tty_struct *tty;
1780 struct tty_driver *driver;
1782 dev_t device = inode->i_rdev;
1783 unsigned short saved_flags = filp->f_flags;
1785 nonseekable_open(inode, filp);
1788 noctty = filp->f_flags & O_NOCTTY;
1792 mutex_lock(&tty_mutex);
1794 if (device == MKDEV(TTYAUX_MAJOR, 0)) {
1795 tty = get_current_tty();
1797 mutex_unlock(&tty_mutex);
1800 driver = tty->driver;
1802 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1807 if (device == MKDEV(TTY_MAJOR, 0)) {
1808 extern struct tty_driver *console_driver;
1809 driver = console_driver;
1815 if (device == MKDEV(TTYAUX_MAJOR, 1)) {
1816 driver = console_device(&index);
1818 /* Don't let /dev/console block */
1819 filp->f_flags |= O_NONBLOCK;
1823 mutex_unlock(&tty_mutex);
1827 driver = get_tty_driver(device, &index);
1829 mutex_unlock(&tty_mutex);
1833 retval = init_dev(driver, index, &tty);
1834 mutex_unlock(&tty_mutex);
1838 filp->private_data = tty;
1839 file_move(filp, &tty->tty_files);
1840 check_tty_count(tty, "tty_open");
1841 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1842 tty->driver->subtype == PTY_TYPE_MASTER)
1844 #ifdef TTY_DEBUG_HANGUP
1845 printk(KERN_DEBUG "opening %s...", tty->name);
1849 retval = tty->ops->open(tty, filp);
1853 filp->f_flags = saved_flags;
1855 if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) &&
1856 !capable(CAP_SYS_ADMIN))
1860 #ifdef TTY_DEBUG_HANGUP
1861 printk(KERN_DEBUG "error %d in opening %s...", retval,
1865 if (retval != -ERESTARTSYS)
1867 if (signal_pending(current))
1871 * Need to reset f_op in case a hangup happened.
1873 if (filp->f_op == &hung_up_tty_fops)
1874 filp->f_op = &tty_fops;
1878 mutex_lock(&tty_mutex);
1879 spin_lock_irq(¤t->sighand->siglock);
1881 current->signal->leader &&
1882 !current->signal->tty &&
1883 tty->session == NULL)
1884 __proc_set_tty(current, tty);
1885 spin_unlock_irq(¤t->sighand->siglock);
1886 mutex_unlock(&tty_mutex);
1890 /* BKL pushdown: scary code avoidance wrapper */
1891 static int tty_open(struct inode *inode, struct file *filp)
1896 ret = __tty_open(inode, filp);
1903 #ifdef CONFIG_UNIX98_PTYS
1905 * ptmx_open - open a unix 98 pty master
1906 * @inode: inode of device file
1907 * @filp: file pointer to tty
1909 * Allocate a unix98 pty master device from the ptmx driver.
1911 * Locking: tty_mutex protects theinit_dev work. tty->count should
1913 * allocated_ptys_lock handles the list of free pty numbers
1916 static int __ptmx_open(struct inode *inode, struct file *filp)
1918 struct tty_struct *tty;
1922 nonseekable_open(inode, filp);
1924 /* find a device that is not in use. */
1925 index = devpts_new_index();
1929 mutex_lock(&tty_mutex);
1930 retval = init_dev(ptm_driver, index, &tty);
1931 mutex_unlock(&tty_mutex);
1936 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
1937 filp->private_data = tty;
1938 file_move(filp, &tty->tty_files);
1940 retval = devpts_pty_new(tty->link);
1944 check_tty_count(tty, "ptmx_open");
1945 retval = ptm_driver->ops->open(tty, filp);
1952 devpts_kill_index(index);
1956 static int ptmx_open(struct inode *inode, struct file *filp)
1961 ret = __ptmx_open(inode, filp);
1968 * tty_release - vfs callback for close
1969 * @inode: inode of tty
1970 * @filp: file pointer for handle to tty
1972 * Called the last time each file handle is closed that references
1973 * this tty. There may however be several such references.
1976 * Takes bkl. See release_dev
1979 static int tty_release(struct inode *inode, struct file *filp)
1988 * tty_poll - check tty status
1989 * @filp: file being polled
1990 * @wait: poll wait structures to update
1992 * Call the line discipline polling method to obtain the poll
1993 * status of the device.
1995 * Locking: locks called line discipline but ldisc poll method
1996 * may be re-entered freely by other callers.
1999 static unsigned int tty_poll(struct file *filp, poll_table *wait)
2001 struct tty_struct *tty;
2002 struct tty_ldisc *ld;
2005 tty = (struct tty_struct *)filp->private_data;
2006 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_poll"))
2009 ld = tty_ldisc_ref_wait(tty);
2011 ret = (ld->ops->poll)(tty, filp, wait);
2012 tty_ldisc_deref(ld);
2016 static int tty_fasync(int fd, struct file *filp, int on)
2018 struct tty_struct *tty;
2019 unsigned long flags;
2023 tty = (struct tty_struct *)filp->private_data;
2024 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_fasync"))
2027 retval = fasync_helper(fd, filp, on, &tty->fasync);
2034 if (!waitqueue_active(&tty->read_wait))
2035 tty->minimum_to_wake = 1;
2036 spin_lock_irqsave(&tty->ctrl_lock, flags);
2039 type = PIDTYPE_PGID;
2041 pid = task_pid(current);
2044 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2045 retval = __f_setown(filp, pid, type, 0);
2049 if (!tty->fasync && !waitqueue_active(&tty->read_wait))
2050 tty->minimum_to_wake = N_TTY_BUF_SIZE;
2059 * tiocsti - fake input character
2060 * @tty: tty to fake input into
2061 * @p: pointer to character
2063 * Fake input to a tty device. Does the necessary locking and
2066 * FIXME: does not honour flow control ??
2069 * Called functions take tty_ldisc_lock
2070 * current->signal->tty check is safe without locks
2072 * FIXME: may race normal receive processing
2075 static int tiocsti(struct tty_struct *tty, char __user *p)
2078 struct tty_ldisc *ld;
2080 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2082 if (get_user(ch, p))
2084 ld = tty_ldisc_ref_wait(tty);
2085 ld->ops->receive_buf(tty, &ch, &mbz, 1);
2086 tty_ldisc_deref(ld);
2091 * tiocgwinsz - implement window query ioctl
2093 * @arg: user buffer for result
2095 * Copies the kernel idea of the window size into the user buffer.
2097 * Locking: tty->termios_mutex is taken to ensure the winsize data
2101 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2105 mutex_lock(&tty->termios_mutex);
2106 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2107 mutex_unlock(&tty->termios_mutex);
2109 return err ? -EFAULT: 0;
2113 * tty_do_resize - resize event
2114 * @tty: tty being resized
2115 * @real_tty: real tty (not the same as tty if using a pty/tty pair)
2116 * @rows: rows (character)
2117 * @cols: cols (character)
2119 * Update the termios variables and send the neccessary signals to
2120 * peform a terminal resize correctly
2123 int tty_do_resize(struct tty_struct *tty, struct tty_struct *real_tty,
2126 struct pid *pgrp, *rpgrp;
2127 unsigned long flags;
2129 /* For a PTY we need to lock the tty side */
2130 mutex_lock(&real_tty->termios_mutex);
2131 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
2133 /* Get the PID values and reference them so we can
2134 avoid holding the tty ctrl lock while sending signals */
2135 spin_lock_irqsave(&tty->ctrl_lock, flags);
2136 pgrp = get_pid(tty->pgrp);
2137 rpgrp = get_pid(real_tty->pgrp);
2138 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2141 kill_pgrp(pgrp, SIGWINCH, 1);
2142 if (rpgrp != pgrp && rpgrp)
2143 kill_pgrp(rpgrp, SIGWINCH, 1);
2149 real_tty->winsize = *ws;
2151 mutex_unlock(&real_tty->termios_mutex);
2156 * tiocswinsz - implement window size set ioctl
2158 * @arg: user buffer for result
2160 * Copies the user idea of the window size to the kernel. Traditionally
2161 * this is just advisory information but for the Linux console it
2162 * actually has driver level meaning and triggers a VC resize.
2165 * Driver dependant. The default do_resize method takes the
2166 * tty termios mutex and ctrl_lock. The console takes its own lock
2167 * then calls into the default method.
2170 static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty,
2171 struct winsize __user *arg)
2173 struct winsize tmp_ws;
2174 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2177 if (tty->ops->resize)
2178 return tty->ops->resize(tty, real_tty, &tmp_ws);
2180 return tty_do_resize(tty, real_tty, &tmp_ws);
2184 * tioccons - allow admin to move logical console
2185 * @file: the file to become console
2187 * Allow the adminstrator to move the redirected console device
2189 * Locking: uses redirect_lock to guard the redirect information
2192 static int tioccons(struct file *file)
2194 if (!capable(CAP_SYS_ADMIN))
2196 if (file->f_op->write == redirected_tty_write) {
2198 spin_lock(&redirect_lock);
2201 spin_unlock(&redirect_lock);
2206 spin_lock(&redirect_lock);
2208 spin_unlock(&redirect_lock);
2213 spin_unlock(&redirect_lock);
2218 * fionbio - non blocking ioctl
2219 * @file: file to set blocking value
2220 * @p: user parameter
2222 * Historical tty interfaces had a blocking control ioctl before
2223 * the generic functionality existed. This piece of history is preserved
2224 * in the expected tty API of posix OS's.
2226 * Locking: none, the open fle handle ensures it won't go away.
2229 static int fionbio(struct file *file, int __user *p)
2233 if (get_user(nonblock, p))
2236 /* file->f_flags is still BKL protected in the fs layer - vomit */
2239 file->f_flags |= O_NONBLOCK;
2241 file->f_flags &= ~O_NONBLOCK;
2247 * tiocsctty - set controlling tty
2248 * @tty: tty structure
2249 * @arg: user argument
2251 * This ioctl is used to manage job control. It permits a session
2252 * leader to set this tty as the controlling tty for the session.
2255 * Takes tty_mutex() to protect tty instance
2256 * Takes tasklist_lock internally to walk sessions
2257 * Takes ->siglock() when updating signal->tty
2260 static int tiocsctty(struct tty_struct *tty, int arg)
2263 if (current->signal->leader && (task_session(current) == tty->session))
2266 mutex_lock(&tty_mutex);
2268 * The process must be a session leader and
2269 * not have a controlling tty already.
2271 if (!current->signal->leader || current->signal->tty) {
2278 * This tty is already the controlling
2279 * tty for another session group!
2281 if (arg == 1 && capable(CAP_SYS_ADMIN)) {
2285 read_lock(&tasklist_lock);
2286 session_clear_tty(tty->session);
2287 read_unlock(&tasklist_lock);
2293 proc_set_tty(current, tty);
2295 mutex_unlock(&tty_mutex);
2300 * tty_get_pgrp - return a ref counted pgrp pid
2303 * Returns a refcounted instance of the pid struct for the process
2304 * group controlling the tty.
2307 struct pid *tty_get_pgrp(struct tty_struct *tty)
2309 unsigned long flags;
2312 spin_lock_irqsave(&tty->ctrl_lock, flags);
2313 pgrp = get_pid(tty->pgrp);
2314 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2318 EXPORT_SYMBOL_GPL(tty_get_pgrp);
2321 * tiocgpgrp - get process group
2322 * @tty: tty passed by user
2323 * @real_tty: tty side of the tty pased by the user if a pty else the tty
2326 * Obtain the process group of the tty. If there is no process group
2329 * Locking: none. Reference to current->signal->tty is safe.
2332 static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2337 * (tty == real_tty) is a cheap way of
2338 * testing if the tty is NOT a master pty.
2340 if (tty == real_tty && current->signal->tty != real_tty)
2342 pid = tty_get_pgrp(real_tty);
2343 ret = put_user(pid_vnr(pid), p);
2349 * tiocspgrp - attempt to set process group
2350 * @tty: tty passed by user
2351 * @real_tty: tty side device matching tty passed by user
2354 * Set the process group of the tty to the session passed. Only
2355 * permitted where the tty session is our session.
2357 * Locking: RCU, ctrl lock
2360 static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2364 int retval = tty_check_change(real_tty);
2365 unsigned long flags;
2371 if (!current->signal->tty ||
2372 (current->signal->tty != real_tty) ||
2373 (real_tty->session != task_session(current)))
2375 if (get_user(pgrp_nr, p))
2380 pgrp = find_vpid(pgrp_nr);
2385 if (session_of_pgrp(pgrp) != task_session(current))
2388 spin_lock_irqsave(&tty->ctrl_lock, flags);
2389 put_pid(real_tty->pgrp);
2390 real_tty->pgrp = get_pid(pgrp);
2391 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2398 * tiocgsid - get session id
2399 * @tty: tty passed by user
2400 * @real_tty: tty side of the tty pased by the user if a pty else the tty
2401 * @p: pointer to returned session id
2403 * Obtain the session id of the tty. If there is no session
2406 * Locking: none. Reference to current->signal->tty is safe.
2409 static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2412 * (tty == real_tty) is a cheap way of
2413 * testing if the tty is NOT a master pty.
2415 if (tty == real_tty && current->signal->tty != real_tty)
2417 if (!real_tty->session)
2419 return put_user(pid_vnr(real_tty->session), p);
2423 * tiocsetd - set line discipline
2425 * @p: pointer to user data
2427 * Set the line discipline according to user request.
2429 * Locking: see tty_set_ldisc, this function is just a helper
2432 static int tiocsetd(struct tty_struct *tty, int __user *p)
2437 if (get_user(ldisc, p))
2441 ret = tty_set_ldisc(tty, ldisc);
2448 * send_break - performed time break
2449 * @tty: device to break on
2450 * @duration: timeout in mS
2452 * Perform a timed break on hardware that lacks its own driver level
2453 * timed break functionality.
2456 * atomic_write_lock serializes
2460 static int send_break(struct tty_struct *tty, unsigned int duration)
2464 if (tty->ops->break_ctl == NULL)
2467 if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2468 retval = tty->ops->break_ctl(tty, duration);
2470 /* Do the work ourselves */
2471 if (tty_write_lock(tty, 0) < 0)
2473 retval = tty->ops->break_ctl(tty, -1);
2476 if (!signal_pending(current))
2477 msleep_interruptible(duration);
2478 retval = tty->ops->break_ctl(tty, 0);
2480 tty_write_unlock(tty);
2481 if (signal_pending(current))
2488 * tty_tiocmget - get modem status
2490 * @file: user file pointer
2491 * @p: pointer to result
2493 * Obtain the modem status bits from the tty driver if the feature
2494 * is supported. Return -EINVAL if it is not available.
2496 * Locking: none (up to the driver)
2499 static int tty_tiocmget(struct tty_struct *tty, struct file *file, int __user *p)
2501 int retval = -EINVAL;
2503 if (tty->ops->tiocmget) {
2504 retval = tty->ops->tiocmget(tty, file);
2507 retval = put_user(retval, p);
2513 * tty_tiocmset - set modem status
2515 * @file: user file pointer
2516 * @cmd: command - clear bits, set bits or set all
2517 * @p: pointer to desired bits
2519 * Set the modem status bits from the tty driver if the feature
2520 * is supported. Return -EINVAL if it is not available.
2522 * Locking: none (up to the driver)
2525 static int tty_tiocmset(struct tty_struct *tty, struct file *file, unsigned int cmd,
2529 unsigned int set, clear, val;
2531 if (tty->ops->tiocmset == NULL)
2534 retval = get_user(val, p);
2550 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2551 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2552 return tty->ops->tiocmset(tty, file, set, clear);
2556 * Split this up, as gcc can choke on it otherwise..
2558 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2560 struct tty_struct *tty, *real_tty;
2561 void __user *p = (void __user *)arg;
2563 struct tty_ldisc *ld;
2564 struct inode *inode = file->f_dentry->d_inode;
2566 tty = (struct tty_struct *)file->private_data;
2567 if (tty_paranoia_check(tty, inode, "tty_ioctl"))
2571 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2572 tty->driver->subtype == PTY_TYPE_MASTER)
2573 real_tty = tty->link;
2577 * Factor out some common prep work
2585 retval = tty_check_change(tty);
2588 if (cmd != TIOCCBRK) {
2589 tty_wait_until_sent(tty, 0);
2590 if (signal_pending(current))
2601 return tiocsti(tty, p);
2603 return tiocgwinsz(tty, p);
2605 return tiocswinsz(tty, real_tty, p);
2607 return real_tty != tty ? -EINVAL : tioccons(file);
2609 return fionbio(file, p);
2611 set_bit(TTY_EXCLUSIVE, &tty->flags);
2614 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2617 if (current->signal->tty != tty)
2622 return tiocsctty(tty, arg);
2624 return tiocgpgrp(tty, real_tty, p);
2626 return tiocspgrp(tty, real_tty, p);
2628 return tiocgsid(tty, real_tty, p);
2630 return put_user(tty->ldisc.ops->num, (int __user *)p);
2632 return tiocsetd(tty, p);
2636 case TIOCSBRK: /* Turn break on, unconditionally */
2637 if (tty->ops->break_ctl)
2638 return tty->ops->break_ctl(tty, -1);
2640 case TIOCCBRK: /* Turn break off, unconditionally */
2641 if (tty->ops->break_ctl)
2642 return tty->ops->break_ctl(tty, 0);
2644 case TCSBRK: /* SVID version: non-zero arg --> no break */
2645 /* non-zero arg means wait for all output data
2646 * to be sent (performed above) but don't send break.
2647 * This is used by the tcdrain() termios function.
2650 return send_break(tty, 250);
2652 case TCSBRKP: /* support for POSIX tcsendbreak() */
2653 return send_break(tty, arg ? arg*100 : 250);
2656 return tty_tiocmget(tty, file, p);
2660 return tty_tiocmset(tty, file, cmd, p);
2665 /* flush tty buffer and allow ldisc to process ioctl */
2666 tty_buffer_flush(tty);
2671 if (tty->ops->ioctl) {
2672 retval = (tty->ops->ioctl)(tty, file, cmd, arg);
2673 if (retval != -ENOIOCTLCMD)
2676 ld = tty_ldisc_ref_wait(tty);
2678 if (ld->ops->ioctl) {
2679 retval = ld->ops->ioctl(tty, file, cmd, arg);
2680 if (retval == -ENOIOCTLCMD)
2683 tty_ldisc_deref(ld);
2687 #ifdef CONFIG_COMPAT
2688 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2691 struct inode *inode = file->f_dentry->d_inode;
2692 struct tty_struct *tty = file->private_data;
2693 struct tty_ldisc *ld;
2694 int retval = -ENOIOCTLCMD;
2696 if (tty_paranoia_check(tty, inode, "tty_ioctl"))
2699 if (tty->ops->compat_ioctl) {
2700 retval = (tty->ops->compat_ioctl)(tty, file, cmd, arg);
2701 if (retval != -ENOIOCTLCMD)
2705 ld = tty_ldisc_ref_wait(tty);
2706 if (ld->ops->compat_ioctl)
2707 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
2708 tty_ldisc_deref(ld);
2715 * This implements the "Secure Attention Key" --- the idea is to
2716 * prevent trojan horses by killing all processes associated with this
2717 * tty when the user hits the "Secure Attention Key". Required for
2718 * super-paranoid applications --- see the Orange Book for more details.
2720 * This code could be nicer; ideally it should send a HUP, wait a few
2721 * seconds, then send a INT, and then a KILL signal. But you then
2722 * have to coordinate with the init process, since all processes associated
2723 * with the current tty must be dead before the new getty is allowed
2726 * Now, if it would be correct ;-/ The current code has a nasty hole -
2727 * it doesn't catch files in flight. We may send the descriptor to ourselves
2728 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
2730 * Nasty bug: do_SAK is being called in interrupt context. This can
2731 * deadlock. We punt it up to process context. AKPM - 16Mar2001
2733 void __do_SAK(struct tty_struct *tty)
2738 struct task_struct *g, *p;
2739 struct pid *session;
2742 struct fdtable *fdt;
2746 session = tty->session;
2748 tty_ldisc_flush(tty);
2750 tty_driver_flush_buffer(tty);
2752 read_lock(&tasklist_lock);
2753 /* Kill the entire session */
2754 do_each_pid_task(session, PIDTYPE_SID, p) {
2755 printk(KERN_NOTICE "SAK: killed process %d"
2756 " (%s): task_session_nr(p)==tty->session\n",
2757 task_pid_nr(p), p->comm);
2758 send_sig(SIGKILL, p, 1);
2759 } while_each_pid_task(session, PIDTYPE_SID, p);
2760 /* Now kill any processes that happen to have the
2763 do_each_thread(g, p) {
2764 if (p->signal->tty == tty) {
2765 printk(KERN_NOTICE "SAK: killed process %d"
2766 " (%s): task_session_nr(p)==tty->session\n",
2767 task_pid_nr(p), p->comm);
2768 send_sig(SIGKILL, p, 1);
2774 * We don't take a ref to the file, so we must
2775 * hold ->file_lock instead.
2777 spin_lock(&p->files->file_lock);
2778 fdt = files_fdtable(p->files);
2779 for (i = 0; i < fdt->max_fds; i++) {
2780 filp = fcheck_files(p->files, i);
2783 if (filp->f_op->read == tty_read &&
2784 filp->private_data == tty) {
2785 printk(KERN_NOTICE "SAK: killed process %d"
2786 " (%s): fd#%d opened to the tty\n",
2787 task_pid_nr(p), p->comm, i);
2788 force_sig(SIGKILL, p);
2792 spin_unlock(&p->files->file_lock);
2795 } while_each_thread(g, p);
2796 read_unlock(&tasklist_lock);
2800 static void do_SAK_work(struct work_struct *work)
2802 struct tty_struct *tty =
2803 container_of(work, struct tty_struct, SAK_work);
2808 * The tq handling here is a little racy - tty->SAK_work may already be queued.
2809 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
2810 * the values which we write to it will be identical to the values which it
2811 * already has. --akpm
2813 void do_SAK(struct tty_struct *tty)
2817 schedule_work(&tty->SAK_work);
2820 EXPORT_SYMBOL(do_SAK);
2823 * initialize_tty_struct
2824 * @tty: tty to initialize
2826 * This subroutine initializes a tty structure that has been newly
2829 * Locking: none - tty in question must not be exposed at this point
2832 static void initialize_tty_struct(struct tty_struct *tty)
2834 memset(tty, 0, sizeof(struct tty_struct));
2835 kref_init(&tty->kref);
2836 tty->magic = TTY_MAGIC;
2837 tty_ldisc_init(tty);
2838 tty->session = NULL;
2840 tty->overrun_time = jiffies;
2841 tty->buf.head = tty->buf.tail = NULL;
2842 tty_buffer_init(tty);
2843 mutex_init(&tty->termios_mutex);
2844 init_waitqueue_head(&tty->write_wait);
2845 init_waitqueue_head(&tty->read_wait);
2846 INIT_WORK(&tty->hangup_work, do_tty_hangup);
2847 mutex_init(&tty->atomic_read_lock);
2848 mutex_init(&tty->atomic_write_lock);
2849 spin_lock_init(&tty->read_lock);
2850 spin_lock_init(&tty->ctrl_lock);
2851 INIT_LIST_HEAD(&tty->tty_files);
2852 INIT_WORK(&tty->SAK_work, do_SAK_work);
2856 * tty_put_char - write one character to a tty
2860 * Write one byte to the tty using the provided put_char method
2861 * if present. Returns the number of characters successfully output.
2863 * Note: the specific put_char operation in the driver layer may go
2864 * away soon. Don't call it directly, use this method
2867 int tty_put_char(struct tty_struct *tty, unsigned char ch)
2869 if (tty->ops->put_char)
2870 return tty->ops->put_char(tty, ch);
2871 return tty->ops->write(tty, &ch, 1);
2874 EXPORT_SYMBOL_GPL(tty_put_char);
2876 static struct class *tty_class;
2879 * tty_register_device - register a tty device
2880 * @driver: the tty driver that describes the tty device
2881 * @index: the index in the tty driver for this tty device
2882 * @device: a struct device that is associated with this tty device.
2883 * This field is optional, if there is no known struct device
2884 * for this tty device it can be set to NULL safely.
2886 * Returns a pointer to the struct device for this tty device
2887 * (or ERR_PTR(-EFOO) on error).
2889 * This call is required to be made to register an individual tty device
2890 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
2891 * that bit is not set, this function should not be called by a tty
2897 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
2898 struct device *device)
2901 dev_t dev = MKDEV(driver->major, driver->minor_start) + index;
2903 if (index >= driver->num) {
2904 printk(KERN_ERR "Attempt to register invalid tty line number "
2906 return ERR_PTR(-EINVAL);
2909 if (driver->type == TTY_DRIVER_TYPE_PTY)
2910 pty_line_name(driver, index, name);
2912 tty_line_name(driver, index, name);
2914 return device_create_drvdata(tty_class, device, dev, NULL, name);
2918 * tty_unregister_device - unregister a tty device
2919 * @driver: the tty driver that describes the tty device
2920 * @index: the index in the tty driver for this tty device
2922 * If a tty device is registered with a call to tty_register_device() then
2923 * this function must be called when the tty device is gone.
2928 void tty_unregister_device(struct tty_driver *driver, unsigned index)
2930 device_destroy(tty_class,
2931 MKDEV(driver->major, driver->minor_start) + index);
2934 EXPORT_SYMBOL(tty_register_device);
2935 EXPORT_SYMBOL(tty_unregister_device);
2937 struct tty_driver *alloc_tty_driver(int lines)
2939 struct tty_driver *driver;
2941 driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
2943 driver->magic = TTY_DRIVER_MAGIC;
2944 driver->num = lines;
2945 /* later we'll move allocation of tables here */
2950 void put_tty_driver(struct tty_driver *driver)
2955 void tty_set_operations(struct tty_driver *driver,
2956 const struct tty_operations *op)
2961 EXPORT_SYMBOL(alloc_tty_driver);
2962 EXPORT_SYMBOL(put_tty_driver);
2963 EXPORT_SYMBOL(tty_set_operations);
2966 * Called by a tty driver to register itself.
2968 int tty_register_driver(struct tty_driver *driver)
2975 if (driver->flags & TTY_DRIVER_INSTALLED)
2978 if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM) && driver->num) {
2979 p = kzalloc(driver->num * 3 * sizeof(void *), GFP_KERNEL);
2984 if (!driver->major) {
2985 error = alloc_chrdev_region(&dev, driver->minor_start,
2986 driver->num, driver->name);
2988 driver->major = MAJOR(dev);
2989 driver->minor_start = MINOR(dev);
2992 dev = MKDEV(driver->major, driver->minor_start);
2993 error = register_chrdev_region(dev, driver->num, driver->name);
3001 driver->ttys = (struct tty_struct **)p;
3002 driver->termios = (struct ktermios **)(p + driver->num);
3003 driver->termios_locked = (struct ktermios **)
3004 (p + driver->num * 2);
3006 driver->ttys = NULL;
3007 driver->termios = NULL;
3008 driver->termios_locked = NULL;
3011 cdev_init(&driver->cdev, &tty_fops);
3012 driver->cdev.owner = driver->owner;
3013 error = cdev_add(&driver->cdev, dev, driver->num);
3015 unregister_chrdev_region(dev, driver->num);
3016 driver->ttys = NULL;
3017 driver->termios = driver->termios_locked = NULL;
3022 mutex_lock(&tty_mutex);
3023 list_add(&driver->tty_drivers, &tty_drivers);
3024 mutex_unlock(&tty_mutex);
3026 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
3027 for (i = 0; i < driver->num; i++)
3028 tty_register_device(driver, i, NULL);
3030 proc_tty_register_driver(driver);
3034 EXPORT_SYMBOL(tty_register_driver);
3037 * Called by a tty driver to unregister itself.
3039 int tty_unregister_driver(struct tty_driver *driver)
3042 struct ktermios *tp;
3045 if (driver->refcount)
3048 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3050 mutex_lock(&tty_mutex);
3051 list_del(&driver->tty_drivers);
3052 mutex_unlock(&tty_mutex);
3055 * Free the termios and termios_locked structures because
3056 * we don't want to get memory leaks when modular tty
3057 * drivers are removed from the kernel.
3059 for (i = 0; i < driver->num; i++) {
3060 tp = driver->termios[i];
3062 driver->termios[i] = NULL;
3065 tp = driver->termios_locked[i];
3067 driver->termios_locked[i] = NULL;
3070 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3071 tty_unregister_device(driver, i);
3074 proc_tty_unregister_driver(driver);
3075 driver->ttys = NULL;
3076 driver->termios = driver->termios_locked = NULL;
3078 cdev_del(&driver->cdev);
3081 EXPORT_SYMBOL(tty_unregister_driver);
3083 dev_t tty_devnum(struct tty_struct *tty)
3085 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3087 EXPORT_SYMBOL(tty_devnum);
3089 void proc_clear_tty(struct task_struct *p)
3091 struct tty_struct *tty;
3092 spin_lock_irq(&p->sighand->siglock);
3093 tty = p->signal->tty;
3094 p->signal->tty = NULL;
3095 spin_unlock_irq(&p->sighand->siglock);
3099 /* Called under the sighand lock */
3101 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3104 unsigned long flags;
3105 /* We should not have a session or pgrp to put here but.... */
3106 spin_lock_irqsave(&tty->ctrl_lock, flags);
3107 put_pid(tty->session);
3109 tty->pgrp = get_pid(task_pgrp(tsk));
3110 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
3111 tty->session = get_pid(task_session(tsk));
3112 if (tsk->signal->tty) {
3113 printk(KERN_DEBUG "tty not NULL!!\n");
3114 tty_kref_put(tsk->signal->tty);
3117 put_pid(tsk->signal->tty_old_pgrp);
3118 tsk->signal->tty = tty_kref_get(tty);
3119 tsk->signal->tty_old_pgrp = NULL;
3122 static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3124 spin_lock_irq(&tsk->sighand->siglock);
3125 __proc_set_tty(tsk, tty);
3126 spin_unlock_irq(&tsk->sighand->siglock);
3129 struct tty_struct *get_current_tty(void)
3131 struct tty_struct *tty;
3132 WARN_ON_ONCE(!mutex_is_locked(&tty_mutex));
3133 tty = current->signal->tty;
3135 * session->tty can be changed/cleared from under us, make sure we
3136 * issue the load. The obtained pointer, when not NULL, is valid as
3137 * long as we hold tty_mutex.
3142 EXPORT_SYMBOL_GPL(get_current_tty);
3145 * Initialize the console device. This is called *early*, so
3146 * we can't necessarily depend on lots of kernel help here.
3147 * Just do some early initializations, and do the complex setup
3150 void __init console_init(void)
3154 /* Setup the default TTY line discipline. */
3158 * set up the console device so that later boot sequences can
3159 * inform about problems etc..
3161 call = __con_initcall_start;
3162 while (call < __con_initcall_end) {
3168 static int __init tty_class_init(void)
3170 tty_class = class_create(THIS_MODULE, "tty");
3171 if (IS_ERR(tty_class))
3172 return PTR_ERR(tty_class);
3176 postcore_initcall(tty_class_init);
3178 /* 3/2004 jmc: why do these devices exist? */
3180 static struct cdev tty_cdev, console_cdev;
3181 #ifdef CONFIG_UNIX98_PTYS
3182 static struct cdev ptmx_cdev;
3185 static struct cdev vc0_cdev;
3189 * Ok, now we can initialize the rest of the tty devices and can count
3190 * on memory allocations, interrupts etc..
3192 static int __init tty_init(void)
3194 cdev_init(&tty_cdev, &tty_fops);
3195 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3196 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3197 panic("Couldn't register /dev/tty driver\n");
3198 device_create_drvdata(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL,
3201 cdev_init(&console_cdev, &console_fops);
3202 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3203 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3204 panic("Couldn't register /dev/console driver\n");
3205 device_create_drvdata(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 1), NULL,
3208 #ifdef CONFIG_UNIX98_PTYS
3209 cdev_init(&ptmx_cdev, &ptmx_fops);
3210 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
3211 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
3212 panic("Couldn't register /dev/ptmx driver\n");
3213 device_create_drvdata(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
3217 cdev_init(&vc0_cdev, &console_fops);
3218 if (cdev_add(&vc0_cdev, MKDEV(TTY_MAJOR, 0), 1) ||
3219 register_chrdev_region(MKDEV(TTY_MAJOR, 0), 1, "/dev/vc/0") < 0)
3220 panic("Couldn't register /dev/tty0 driver\n");
3221 device_create_drvdata(tty_class, NULL, MKDEV(TTY_MAJOR, 0), NULL, "tty0");
3227 module_init(tty_init);