2 * Copyright (C) 1991, 1992 Linus Torvalds
6 * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles
7 * or rs-channels. It also implements echoing, cooked mode etc.
9 * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.
11 * Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the
12 * tty_struct and tty_queue structures. Previously there was an array
13 * of 256 tty_struct's which was statically allocated, and the
14 * tty_queue structures were allocated at boot time. Both are now
15 * dynamically allocated only when the tty is open.
17 * Also restructured routines so that there is more of a separation
18 * between the high-level tty routines (tty_io.c and tty_ioctl.c) and
19 * the low-level tty routines (serial.c, pty.c, console.c). This
20 * makes for cleaner and more compact code. -TYT, 9/17/92
22 * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
23 * which can be dynamically activated and de-activated by the line
24 * discipline handling modules (like SLIP).
26 * NOTE: pay no attention to the line discipline code (yet); its
27 * interface is still subject to change in this version...
30 * Added functionality to the OPOST tty handling. No delays, but all
31 * other bits should be there.
32 * -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993.
34 * Rewrote canonical mode and added more termios flags.
35 * -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94
37 * Reorganized FASYNC support so mouse code can share it.
38 * -- ctm@ardi.com, 9Sep95
40 * New TIOCLINUX variants added.
41 * -- mj@k332.feld.cvut.cz, 19-Nov-95
43 * Restrict vt switching via ioctl()
44 * -- grif@cs.ucr.edu, 5-Dec-95
46 * Move console and virtual terminal code to more appropriate files,
47 * implement CONFIG_VT and generalize console device interface.
48 * -- Marko Kohtala <Marko.Kohtala@hut.fi>, March 97
50 * Rewrote tty_init_dev and tty_release_dev to eliminate races.
51 * -- Bill Hawes <whawes@star.net>, June 97
53 * Added devfs support.
54 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 13-Jan-1998
56 * Added support for a Unix98-style ptmx device.
57 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
59 * Reduced memory usage for older ARM systems
60 * -- Russell King <rmk@arm.linux.org.uk>
62 * Move do_SAK() into process context. Less stack use in devfs functions.
63 * alloc_tty_struct() always uses kmalloc()
64 * -- Andrew Morton <andrewm@uow.edu.eu> 17Mar01
67 #include <linux/types.h>
68 #include <linux/major.h>
69 #include <linux/errno.h>
70 #include <linux/signal.h>
71 #include <linux/fcntl.h>
72 #include <linux/sched.h>
73 #include <linux/interrupt.h>
74 #include <linux/tty.h>
75 #include <linux/tty_driver.h>
76 #include <linux/tty_flip.h>
77 #include <linux/devpts_fs.h>
78 #include <linux/file.h>
79 #include <linux/fdtable.h>
80 #include <linux/console.h>
81 #include <linux/timer.h>
82 #include <linux/ctype.h>
85 #include <linux/string.h>
86 #include <linux/slab.h>
87 #include <linux/poll.h>
88 #include <linux/proc_fs.h>
89 #include <linux/init.h>
90 #include <linux/module.h>
91 #include <linux/device.h>
92 #include <linux/wait.h>
93 #include <linux/bitops.h>
94 #include <linux/delay.h>
95 #include <linux/seq_file.h>
96 #include <linux/serial.h>
97 #include <linux/ratelimit.h>
99 #include <linux/uaccess.h>
101 #include <linux/kbd_kern.h>
102 #include <linux/vt_kern.h>
103 #include <linux/selection.h>
105 #include <linux/kmod.h>
106 #include <linux/nsproxy.h>
108 #undef TTY_DEBUG_HANGUP
109 #ifdef TTY_DEBUG_HANGUP
110 # define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args)
112 # define tty_debug_hangup(tty, f, args...) do { } while (0)
115 #define TTY_PARANOIA_CHECK 1
116 #define CHECK_TTY_COUNT 1
118 struct ktermios tty_std_termios = { /* for the benefit of tty drivers */
119 .c_iflag = ICRNL | IXON,
120 .c_oflag = OPOST | ONLCR,
121 .c_cflag = B38400 | CS8 | CREAD | HUPCL,
122 .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
123 ECHOCTL | ECHOKE | IEXTEN,
129 EXPORT_SYMBOL(tty_std_termios);
131 /* This list gets poked at by procfs and various bits of boot up code. This
132 could do with some rationalisation such as pulling the tty proc function
135 LIST_HEAD(tty_drivers); /* linked list of tty drivers */
137 /* Mutex to protect creating and releasing a tty. This is shared with
138 vt.c for deeply disgusting hack reasons */
139 DEFINE_MUTEX(tty_mutex);
140 EXPORT_SYMBOL(tty_mutex);
142 /* Spinlock to protect the tty->tty_files list */
143 DEFINE_SPINLOCK(tty_files_lock);
145 static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
146 static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
147 ssize_t redirected_tty_write(struct file *, const char __user *,
149 static unsigned int tty_poll(struct file *, poll_table *);
150 static int tty_open(struct inode *, struct file *);
151 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
153 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
156 #define tty_compat_ioctl NULL
158 static int __tty_fasync(int fd, struct file *filp, int on);
159 static int tty_fasync(int fd, struct file *filp, int on);
160 static void release_tty(struct tty_struct *tty, int idx);
163 * free_tty_struct - free a disused tty
164 * @tty: tty struct to free
166 * Free the write buffers, tty queue and tty memory itself.
168 * Locking: none. Must be called after tty is definitely unused
171 void free_tty_struct(struct tty_struct *tty)
175 tty_ldisc_deinit(tty);
176 put_device(tty->dev);
177 kfree(tty->write_buf);
178 tty->magic = 0xDEADDEAD;
182 static inline struct tty_struct *file_tty(struct file *file)
184 return ((struct tty_file_private *)file->private_data)->tty;
187 int tty_alloc_file(struct file *file)
189 struct tty_file_private *priv;
191 priv = kmalloc(sizeof(*priv), GFP_KERNEL);
195 file->private_data = priv;
200 /* Associate a new file with the tty structure */
201 void tty_add_file(struct tty_struct *tty, struct file *file)
203 struct tty_file_private *priv = file->private_data;
208 spin_lock(&tty_files_lock);
209 list_add(&priv->list, &tty->tty_files);
210 spin_unlock(&tty_files_lock);
214 * tty_free_file - free file->private_data
216 * This shall be used only for fail path handling when tty_add_file was not
219 void tty_free_file(struct file *file)
221 struct tty_file_private *priv = file->private_data;
223 file->private_data = NULL;
227 /* Delete file from its tty */
228 static void tty_del_file(struct file *file)
230 struct tty_file_private *priv = file->private_data;
232 spin_lock(&tty_files_lock);
233 list_del(&priv->list);
234 spin_unlock(&tty_files_lock);
239 #define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base)
242 * tty_name - return tty naming
243 * @tty: tty structure
245 * Convert a tty structure into a name. The name reflects the kernel
246 * naming policy and if udev is in use may not reflect user space
251 const char *tty_name(const struct tty_struct *tty)
253 if (!tty) /* Hmm. NULL pointer. That's fun. */
258 EXPORT_SYMBOL(tty_name);
260 const char *tty_driver_name(const struct tty_struct *tty)
262 if (!tty || !tty->driver)
264 return tty->driver->name;
267 static int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
270 #ifdef TTY_PARANOIA_CHECK
272 pr_warn("(%d:%d): %s: NULL tty\n",
273 imajor(inode), iminor(inode), routine);
276 if (tty->magic != TTY_MAGIC) {
277 pr_warn("(%d:%d): %s: bad magic number\n",
278 imajor(inode), iminor(inode), routine);
285 /* Caller must hold tty_lock */
286 static int check_tty_count(struct tty_struct *tty, const char *routine)
288 #ifdef CHECK_TTY_COUNT
292 spin_lock(&tty_files_lock);
293 list_for_each(p, &tty->tty_files) {
296 spin_unlock(&tty_files_lock);
297 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
298 tty->driver->subtype == PTY_TYPE_SLAVE &&
299 tty->link && tty->link->count)
301 if (tty->count != count) {
302 tty_warn(tty, "%s: tty->count(%d) != #fd's(%d)\n",
303 routine, tty->count, count);
311 * get_tty_driver - find device of a tty
312 * @dev_t: device identifier
313 * @index: returns the index of the tty
315 * This routine returns a tty driver structure, given a device number
316 * and also passes back the index number.
318 * Locking: caller must hold tty_mutex
321 static struct tty_driver *get_tty_driver(dev_t device, int *index)
323 struct tty_driver *p;
325 list_for_each_entry(p, &tty_drivers, tty_drivers) {
326 dev_t base = MKDEV(p->major, p->minor_start);
327 if (device < base || device >= base + p->num)
329 *index = device - base;
330 return tty_driver_kref_get(p);
335 #ifdef CONFIG_CONSOLE_POLL
338 * tty_find_polling_driver - find device of a polled tty
339 * @name: name string to match
340 * @line: pointer to resulting tty line nr
342 * This routine returns a tty driver structure, given a name
343 * and the condition that the tty driver is capable of polled
346 struct tty_driver *tty_find_polling_driver(char *name, int *line)
348 struct tty_driver *p, *res = NULL;
353 for (str = name; *str; str++)
354 if ((*str >= '0' && *str <= '9') || *str == ',')
360 tty_line = simple_strtoul(str, &str, 10);
362 mutex_lock(&tty_mutex);
363 /* Search through the tty devices to look for a match */
364 list_for_each_entry(p, &tty_drivers, tty_drivers) {
365 if (strncmp(name, p->name, len) != 0)
373 if (tty_line >= 0 && tty_line < p->num && p->ops &&
374 p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) {
375 res = tty_driver_kref_get(p);
380 mutex_unlock(&tty_mutex);
384 EXPORT_SYMBOL_GPL(tty_find_polling_driver);
388 * tty_check_change - check for POSIX terminal changes
391 * If we try to write to, or set the state of, a terminal and we're
392 * not in the foreground, send a SIGTTOU. If the signal is blocked or
393 * ignored, go ahead and perform the operation. (POSIX 7.2)
398 int __tty_check_change(struct tty_struct *tty, int sig)
401 struct pid *pgrp, *tty_pgrp;
404 if (current->signal->tty != tty)
408 pgrp = task_pgrp(current);
410 spin_lock_irqsave(&tty->ctrl_lock, flags);
411 tty_pgrp = tty->pgrp;
412 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
414 if (tty_pgrp && pgrp != tty->pgrp) {
415 if (is_ignored(sig)) {
418 } else if (is_current_pgrp_orphaned())
421 kill_pgrp(pgrp, sig, 1);
422 set_thread_flag(TIF_SIGPENDING);
429 tty_warn(tty, "sig=%d, tty->pgrp == NULL!\n", sig);
434 int tty_check_change(struct tty_struct *tty)
436 return __tty_check_change(tty, SIGTTOU);
438 EXPORT_SYMBOL(tty_check_change);
440 static ssize_t hung_up_tty_read(struct file *file, char __user *buf,
441 size_t count, loff_t *ppos)
446 static ssize_t hung_up_tty_write(struct file *file, const char __user *buf,
447 size_t count, loff_t *ppos)
452 /* No kernel lock held - none needed ;) */
453 static unsigned int hung_up_tty_poll(struct file *filp, poll_table *wait)
455 return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM;
458 static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
461 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
464 static long hung_up_tty_compat_ioctl(struct file *file,
465 unsigned int cmd, unsigned long arg)
467 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
470 static const struct file_operations tty_fops = {
475 .unlocked_ioctl = tty_ioctl,
476 .compat_ioctl = tty_compat_ioctl,
478 .release = tty_release,
479 .fasync = tty_fasync,
482 static const struct file_operations console_fops = {
485 .write = redirected_tty_write,
487 .unlocked_ioctl = tty_ioctl,
488 .compat_ioctl = tty_compat_ioctl,
490 .release = tty_release,
491 .fasync = tty_fasync,
494 static const struct file_operations hung_up_tty_fops = {
496 .read = hung_up_tty_read,
497 .write = hung_up_tty_write,
498 .poll = hung_up_tty_poll,
499 .unlocked_ioctl = hung_up_tty_ioctl,
500 .compat_ioctl = hung_up_tty_compat_ioctl,
501 .release = tty_release,
504 static DEFINE_SPINLOCK(redirect_lock);
505 static struct file *redirect;
508 void proc_clear_tty(struct task_struct *p)
511 struct tty_struct *tty;
512 spin_lock_irqsave(&p->sighand->siglock, flags);
513 tty = p->signal->tty;
514 p->signal->tty = NULL;
515 spin_unlock_irqrestore(&p->sighand->siglock, flags);
520 * proc_set_tty - set the controlling terminal
522 * Only callable by the session leader and only if it does not already have
523 * a controlling terminal.
525 * Caller must hold: tty_lock()
526 * a readlock on tasklist_lock
529 static void __proc_set_tty(struct tty_struct *tty)
533 spin_lock_irqsave(&tty->ctrl_lock, flags);
535 * The session and fg pgrp references will be non-NULL if
536 * tiocsctty() is stealing the controlling tty
538 put_pid(tty->session);
540 tty->pgrp = get_pid(task_pgrp(current));
541 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
542 tty->session = get_pid(task_session(current));
543 if (current->signal->tty) {
544 tty_debug(tty, "current tty %s not NULL!!\n",
545 current->signal->tty->name);
546 tty_kref_put(current->signal->tty);
548 put_pid(current->signal->tty_old_pgrp);
549 current->signal->tty = tty_kref_get(tty);
550 current->signal->tty_old_pgrp = NULL;
553 static void proc_set_tty(struct tty_struct *tty)
555 spin_lock_irq(¤t->sighand->siglock);
557 spin_unlock_irq(¤t->sighand->siglock);
560 struct tty_struct *get_current_tty(void)
562 struct tty_struct *tty;
565 spin_lock_irqsave(¤t->sighand->siglock, flags);
566 tty = tty_kref_get(current->signal->tty);
567 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
570 EXPORT_SYMBOL_GPL(get_current_tty);
572 static void session_clear_tty(struct pid *session)
574 struct task_struct *p;
575 do_each_pid_task(session, PIDTYPE_SID, p) {
577 } while_each_pid_task(session, PIDTYPE_SID, p);
581 * tty_wakeup - request more data
584 * Internal and external helper for wakeups of tty. This function
585 * informs the line discipline if present that the driver is ready
586 * to receive more output data.
589 void tty_wakeup(struct tty_struct *tty)
591 struct tty_ldisc *ld;
593 if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
594 ld = tty_ldisc_ref(tty);
596 if (ld->ops->write_wakeup)
597 ld->ops->write_wakeup(tty);
601 wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
604 EXPORT_SYMBOL_GPL(tty_wakeup);
607 * tty_signal_session_leader - sends SIGHUP to session leader
608 * @tty controlling tty
609 * @exit_session if non-zero, signal all foreground group processes
611 * Send SIGHUP and SIGCONT to the session leader and its process group.
612 * Optionally, signal all processes in the foreground process group.
614 * Returns the number of processes in the session with this tty
615 * as their controlling terminal. This value is used to drop
616 * tty references for those processes.
618 static int tty_signal_session_leader(struct tty_struct *tty, int exit_session)
620 struct task_struct *p;
622 struct pid *tty_pgrp = NULL;
624 read_lock(&tasklist_lock);
626 do_each_pid_task(tty->session, PIDTYPE_SID, p) {
627 spin_lock_irq(&p->sighand->siglock);
628 if (p->signal->tty == tty) {
629 p->signal->tty = NULL;
630 /* We defer the dereferences outside fo
634 if (!p->signal->leader) {
635 spin_unlock_irq(&p->sighand->siglock);
638 __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
639 __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
640 put_pid(p->signal->tty_old_pgrp); /* A noop */
641 spin_lock(&tty->ctrl_lock);
642 tty_pgrp = get_pid(tty->pgrp);
644 p->signal->tty_old_pgrp = get_pid(tty->pgrp);
645 spin_unlock(&tty->ctrl_lock);
646 spin_unlock_irq(&p->sighand->siglock);
647 } while_each_pid_task(tty->session, PIDTYPE_SID, p);
649 read_unlock(&tasklist_lock);
653 kill_pgrp(tty_pgrp, SIGHUP, exit_session);
661 * __tty_hangup - actual handler for hangup events
664 * This can be called by a "kworker" kernel thread. That is process
665 * synchronous but doesn't hold any locks, so we need to make sure we
666 * have the appropriate locks for what we're doing.
668 * The hangup event clears any pending redirections onto the hung up
669 * device. It ensures future writes will error and it does the needed
670 * line discipline hangup and signal delivery. The tty object itself
675 * redirect lock for undoing redirection
676 * file list lock for manipulating list of ttys
677 * tty_ldiscs_lock from called functions
678 * termios_rwsem resetting termios data
679 * tasklist_lock to walk task list for hangup event
680 * ->siglock to protect ->signal/->sighand
682 static void __tty_hangup(struct tty_struct *tty, int exit_session)
684 struct file *cons_filp = NULL;
685 struct file *filp, *f = NULL;
686 struct tty_file_private *priv;
687 int closecount = 0, n;
694 spin_lock(&redirect_lock);
695 if (redirect && file_tty(redirect) == tty) {
699 spin_unlock(&redirect_lock);
703 if (test_bit(TTY_HUPPED, &tty->flags)) {
708 /* inuse_filps is protected by the single tty lock,
709 this really needs to change if we want to flush the
710 workqueue with the lock held */
711 check_tty_count(tty, "tty_hangup");
713 spin_lock(&tty_files_lock);
714 /* This breaks for file handles being sent over AF_UNIX sockets ? */
715 list_for_each_entry(priv, &tty->tty_files, list) {
717 if (filp->f_op->write == redirected_tty_write)
719 if (filp->f_op->write != tty_write)
722 __tty_fasync(-1, filp, 0); /* can't block */
723 filp->f_op = &hung_up_tty_fops;
725 spin_unlock(&tty_files_lock);
727 refs = tty_signal_session_leader(tty, exit_session);
728 /* Account for the p->signal references we killed */
732 tty_ldisc_hangup(tty);
734 spin_lock_irq(&tty->ctrl_lock);
735 clear_bit(TTY_THROTTLED, &tty->flags);
736 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
737 put_pid(tty->session);
741 tty->ctrl_status = 0;
742 spin_unlock_irq(&tty->ctrl_lock);
745 * If one of the devices matches a console pointer, we
746 * cannot just call hangup() because that will cause
747 * tty->count and state->count to go out of sync.
748 * So we just call close() the right number of times.
752 for (n = 0; n < closecount; n++)
753 tty->ops->close(tty, cons_filp);
754 } else if (tty->ops->hangup)
755 tty->ops->hangup(tty);
757 * We don't want to have driver/ldisc interactions beyond
758 * the ones we did here. The driver layer expects no
759 * calls after ->hangup() from the ldisc side. However we
760 * can't yet guarantee all that.
762 set_bit(TTY_HUPPED, &tty->flags);
769 static void do_tty_hangup(struct work_struct *work)
771 struct tty_struct *tty =
772 container_of(work, struct tty_struct, hangup_work);
774 __tty_hangup(tty, 0);
778 * tty_hangup - trigger a hangup event
779 * @tty: tty to hangup
781 * A carrier loss (virtual or otherwise) has occurred on this like
782 * schedule a hangup sequence to run after this event.
785 void tty_hangup(struct tty_struct *tty)
787 tty_debug_hangup(tty, "hangup\n");
788 schedule_work(&tty->hangup_work);
791 EXPORT_SYMBOL(tty_hangup);
794 * tty_vhangup - process vhangup
795 * @tty: tty to hangup
797 * The user has asked via system call for the terminal to be hung up.
798 * We do this synchronously so that when the syscall returns the process
799 * is complete. That guarantee is necessary for security reasons.
802 void tty_vhangup(struct tty_struct *tty)
804 tty_debug_hangup(tty, "vhangup\n");
805 __tty_hangup(tty, 0);
808 EXPORT_SYMBOL(tty_vhangup);
812 * tty_vhangup_self - process vhangup for own ctty
814 * Perform a vhangup on the current controlling tty
817 void tty_vhangup_self(void)
819 struct tty_struct *tty;
821 tty = get_current_tty();
829 * tty_vhangup_session - hangup session leader exit
830 * @tty: tty to hangup
832 * The session leader is exiting and hanging up its controlling terminal.
833 * Every process in the foreground process group is signalled SIGHUP.
835 * We do this synchronously so that when the syscall returns the process
836 * is complete. That guarantee is necessary for security reasons.
839 static void tty_vhangup_session(struct tty_struct *tty)
841 tty_debug_hangup(tty, "session hangup\n");
842 __tty_hangup(tty, 1);
846 * tty_hung_up_p - was tty hung up
847 * @filp: file pointer of tty
849 * Return true if the tty has been subject to a vhangup or a carrier
853 int tty_hung_up_p(struct file *filp)
855 return (filp->f_op == &hung_up_tty_fops);
858 EXPORT_SYMBOL(tty_hung_up_p);
861 * disassociate_ctty - disconnect controlling tty
862 * @on_exit: true if exiting so need to "hang up" the session
864 * This function is typically called only by the session leader, when
865 * it wants to disassociate itself from its controlling tty.
867 * It performs the following functions:
868 * (1) Sends a SIGHUP and SIGCONT to the foreground process group
869 * (2) Clears the tty from being controlling the session
870 * (3) Clears the controlling tty for all processes in the
873 * The argument on_exit is set to 1 if called when a process is
874 * exiting; it is 0 if called by the ioctl TIOCNOTTY.
877 * BTM is taken for hysterical raisins, and held when
878 * called from no_tty().
879 * tty_mutex is taken to protect tty
880 * ->siglock is taken to protect ->signal/->sighand
881 * tasklist_lock is taken to walk process list for sessions
882 * ->siglock is taken to protect ->signal/->sighand
885 void disassociate_ctty(int on_exit)
887 struct tty_struct *tty;
889 if (!current->signal->leader)
892 tty = get_current_tty();
894 if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY) {
895 tty_vhangup_session(tty);
897 struct pid *tty_pgrp = tty_get_pgrp(tty);
899 kill_pgrp(tty_pgrp, SIGHUP, on_exit);
901 kill_pgrp(tty_pgrp, SIGCONT, on_exit);
907 } else if (on_exit) {
908 struct pid *old_pgrp;
909 spin_lock_irq(¤t->sighand->siglock);
910 old_pgrp = current->signal->tty_old_pgrp;
911 current->signal->tty_old_pgrp = NULL;
912 spin_unlock_irq(¤t->sighand->siglock);
914 kill_pgrp(old_pgrp, SIGHUP, on_exit);
915 kill_pgrp(old_pgrp, SIGCONT, on_exit);
921 spin_lock_irq(¤t->sighand->siglock);
922 put_pid(current->signal->tty_old_pgrp);
923 current->signal->tty_old_pgrp = NULL;
925 tty = tty_kref_get(current->signal->tty);
928 spin_lock_irqsave(&tty->ctrl_lock, flags);
929 put_pid(tty->session);
933 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
936 tty_debug_hangup(tty, "no current tty\n");
938 spin_unlock_irq(¤t->sighand->siglock);
939 /* Now clear signal->tty under the lock */
940 read_lock(&tasklist_lock);
941 session_clear_tty(task_session(current));
942 read_unlock(&tasklist_lock);
947 * no_tty - Ensure the current process does not have a controlling tty
951 /* FIXME: Review locking here. The tty_lock never covered any race
952 between a new association and proc_clear_tty but possible we need
953 to protect against this anyway */
954 struct task_struct *tsk = current;
955 disassociate_ctty(0);
961 * stop_tty - propagate flow control
964 * Perform flow control to the driver. May be called
965 * on an already stopped device and will not re-call the driver
968 * This functionality is used by both the line disciplines for
969 * halting incoming flow and by the driver. It may therefore be
970 * called from any context, may be under the tty atomic_write_lock
977 void __stop_tty(struct tty_struct *tty)
986 void stop_tty(struct tty_struct *tty)
990 spin_lock_irqsave(&tty->flow_lock, flags);
992 spin_unlock_irqrestore(&tty->flow_lock, flags);
994 EXPORT_SYMBOL(stop_tty);
997 * start_tty - propagate flow control
1000 * Start a tty that has been stopped if at all possible. If this
1001 * tty was previous stopped and is now being started, the driver
1002 * start method is invoked and the line discipline woken.
1008 void __start_tty(struct tty_struct *tty)
1010 if (!tty->stopped || tty->flow_stopped)
1013 if (tty->ops->start)
1014 tty->ops->start(tty);
1018 void start_tty(struct tty_struct *tty)
1020 unsigned long flags;
1022 spin_lock_irqsave(&tty->flow_lock, flags);
1024 spin_unlock_irqrestore(&tty->flow_lock, flags);
1026 EXPORT_SYMBOL(start_tty);
1028 static void tty_update_time(struct timespec *time)
1030 unsigned long sec = get_seconds();
1033 * We only care if the two values differ in anything other than the
1034 * lower three bits (i.e every 8 seconds). If so, then we can update
1035 * the time of the tty device, otherwise it could be construded as a
1036 * security leak to let userspace know the exact timing of the tty.
1038 if ((sec ^ time->tv_sec) & ~7)
1043 * tty_read - read method for tty device files
1044 * @file: pointer to tty file
1046 * @count: size of user buffer
1049 * Perform the read system call function on this terminal device. Checks
1050 * for hung up devices before calling the line discipline method.
1053 * Locks the line discipline internally while needed. Multiple
1054 * read calls may be outstanding in parallel.
1057 static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
1061 struct inode *inode = file_inode(file);
1062 struct tty_struct *tty = file_tty(file);
1063 struct tty_ldisc *ld;
1065 if (tty_paranoia_check(tty, inode, "tty_read"))
1067 if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags)))
1070 /* We want to wait for the line discipline to sort out in this
1072 ld = tty_ldisc_ref_wait(tty);
1074 i = ld->ops->read(tty, file, buf, count);
1077 tty_ldisc_deref(ld);
1080 tty_update_time(&inode->i_atime);
1085 static void tty_write_unlock(struct tty_struct *tty)
1087 mutex_unlock(&tty->atomic_write_lock);
1088 wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
1091 static int tty_write_lock(struct tty_struct *tty, int ndelay)
1093 if (!mutex_trylock(&tty->atomic_write_lock)) {
1096 if (mutex_lock_interruptible(&tty->atomic_write_lock))
1097 return -ERESTARTSYS;
1103 * Split writes up in sane blocksizes to avoid
1104 * denial-of-service type attacks
1106 static inline ssize_t do_tty_write(
1107 ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
1108 struct tty_struct *tty,
1110 const char __user *buf,
1113 ssize_t ret, written = 0;
1116 ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
1121 * We chunk up writes into a temporary buffer. This
1122 * simplifies low-level drivers immensely, since they
1123 * don't have locking issues and user mode accesses.
1125 * But if TTY_NO_WRITE_SPLIT is set, we should use a
1128 * The default chunk-size is 2kB, because the NTTY
1129 * layer has problems with bigger chunks. It will
1130 * claim to be able to handle more characters than
1133 * FIXME: This can probably go away now except that 64K chunks
1134 * are too likely to fail unless switched to vmalloc...
1137 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
1142 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
1143 if (tty->write_cnt < chunk) {
1144 unsigned char *buf_chunk;
1149 buf_chunk = kmalloc(chunk, GFP_KERNEL);
1154 kfree(tty->write_buf);
1155 tty->write_cnt = chunk;
1156 tty->write_buf = buf_chunk;
1159 /* Do the write .. */
1161 size_t size = count;
1165 if (copy_from_user(tty->write_buf, buf, size))
1167 ret = write(tty, file, tty->write_buf, size);
1176 if (signal_pending(current))
1181 tty_update_time(&file_inode(file)->i_mtime);
1185 tty_write_unlock(tty);
1190 * tty_write_message - write a message to a certain tty, not just the console.
1191 * @tty: the destination tty_struct
1192 * @msg: the message to write
1194 * This is used for messages that need to be redirected to a specific tty.
1195 * We don't put it into the syslog queue right now maybe in the future if
1198 * We must still hold the BTM and test the CLOSING flag for the moment.
1201 void tty_write_message(struct tty_struct *tty, char *msg)
1204 mutex_lock(&tty->atomic_write_lock);
1206 if (tty->ops->write && tty->count > 0)
1207 tty->ops->write(tty, msg, strlen(msg));
1209 tty_write_unlock(tty);
1216 * tty_write - write method for tty device file
1217 * @file: tty file pointer
1218 * @buf: user data to write
1219 * @count: bytes to write
1222 * Write data to a tty device via the line discipline.
1225 * Locks the line discipline as required
1226 * Writes to the tty driver are serialized by the atomic_write_lock
1227 * and are then processed in chunks to the device. The line discipline
1228 * write method will not be invoked in parallel for each device.
1231 static ssize_t tty_write(struct file *file, const char __user *buf,
1232 size_t count, loff_t *ppos)
1234 struct tty_struct *tty = file_tty(file);
1235 struct tty_ldisc *ld;
1238 if (tty_paranoia_check(tty, file_inode(file), "tty_write"))
1240 if (!tty || !tty->ops->write ||
1241 (test_bit(TTY_IO_ERROR, &tty->flags)))
1243 /* Short term debug to catch buggy drivers */
1244 if (tty->ops->write_room == NULL)
1245 tty_err(tty, "missing write_room method\n");
1246 ld = tty_ldisc_ref_wait(tty);
1247 if (!ld->ops->write)
1250 ret = do_tty_write(ld->ops->write, tty, file, buf, count);
1251 tty_ldisc_deref(ld);
1255 ssize_t redirected_tty_write(struct file *file, const char __user *buf,
1256 size_t count, loff_t *ppos)
1258 struct file *p = NULL;
1260 spin_lock(&redirect_lock);
1262 p = get_file(redirect);
1263 spin_unlock(&redirect_lock);
1267 res = vfs_write(p, buf, count, &p->f_pos);
1271 return tty_write(file, buf, count, ppos);
1275 * tty_send_xchar - send priority character
1277 * Send a high priority character to the tty even if stopped
1279 * Locking: none for xchar method, write ordering for write method.
1282 int tty_send_xchar(struct tty_struct *tty, char ch)
1284 int was_stopped = tty->stopped;
1286 if (tty->ops->send_xchar) {
1287 down_read(&tty->termios_rwsem);
1288 tty->ops->send_xchar(tty, ch);
1289 up_read(&tty->termios_rwsem);
1293 if (tty_write_lock(tty, 0) < 0)
1294 return -ERESTARTSYS;
1296 down_read(&tty->termios_rwsem);
1299 tty->ops->write(tty, &ch, 1);
1302 up_read(&tty->termios_rwsem);
1303 tty_write_unlock(tty);
1307 static char ptychar[] = "pqrstuvwxyzabcde";
1310 * pty_line_name - generate name for a pty
1311 * @driver: the tty driver in use
1312 * @index: the minor number
1313 * @p: output buffer of at least 6 bytes
1315 * Generate a name from a driver reference and write it to the output
1320 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1322 int i = index + driver->name_base;
1323 /* ->name is initialized to "ttyp", but "tty" is expected */
1324 sprintf(p, "%s%c%x",
1325 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1326 ptychar[i >> 4 & 0xf], i & 0xf);
1330 * tty_line_name - generate name for a tty
1331 * @driver: the tty driver in use
1332 * @index: the minor number
1333 * @p: output buffer of at least 7 bytes
1335 * Generate a name from a driver reference and write it to the output
1340 static ssize_t tty_line_name(struct tty_driver *driver, int index, char *p)
1342 if (driver->flags & TTY_DRIVER_UNNUMBERED_NODE)
1343 return sprintf(p, "%s", driver->name);
1345 return sprintf(p, "%s%d", driver->name,
1346 index + driver->name_base);
1350 * tty_driver_lookup_tty() - find an existing tty, if any
1351 * @driver: the driver for the tty
1352 * @idx: the minor number
1354 * Return the tty, if found. If not found, return NULL or ERR_PTR() if the
1355 * driver lookup() method returns an error.
1357 * Locking: tty_mutex must be held. If the tty is found, bump the tty kref.
1359 static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
1360 struct inode *inode, int idx)
1362 struct tty_struct *tty;
1364 if (driver->ops->lookup)
1365 tty = driver->ops->lookup(driver, inode, idx);
1367 tty = driver->ttys[idx];
1375 * tty_init_termios - helper for termios setup
1376 * @tty: the tty to set up
1378 * Initialise the termios structures for this tty. Thus runs under
1379 * the tty_mutex currently so we can be relaxed about ordering.
1382 int tty_init_termios(struct tty_struct *tty)
1384 struct ktermios *tp;
1385 int idx = tty->index;
1387 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1388 tty->termios = tty->driver->init_termios;
1390 /* Check for lazy saved data */
1391 tp = tty->driver->termios[idx];
1395 tty->termios = tty->driver->init_termios;
1397 /* Compatibility until drivers always set this */
1398 tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
1399 tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
1402 EXPORT_SYMBOL_GPL(tty_init_termios);
1404 int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty)
1406 int ret = tty_init_termios(tty);
1410 tty_driver_kref_get(driver);
1412 driver->ttys[tty->index] = tty;
1415 EXPORT_SYMBOL_GPL(tty_standard_install);
1418 * tty_driver_install_tty() - install a tty entry in the driver
1419 * @driver: the driver for the tty
1422 * Install a tty object into the driver tables. The tty->index field
1423 * will be set by the time this is called. This method is responsible
1424 * for ensuring any need additional structures are allocated and
1427 * Locking: tty_mutex for now
1429 static int tty_driver_install_tty(struct tty_driver *driver,
1430 struct tty_struct *tty)
1432 return driver->ops->install ? driver->ops->install(driver, tty) :
1433 tty_standard_install(driver, tty);
1437 * tty_driver_remove_tty() - remove a tty from the driver tables
1438 * @driver: the driver for the tty
1439 * @idx: the minor number
1441 * Remvoe a tty object from the driver tables. The tty->index field
1442 * will be set by the time this is called.
1444 * Locking: tty_mutex for now
1446 void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *tty)
1448 if (driver->ops->remove)
1449 driver->ops->remove(driver, tty);
1451 driver->ttys[tty->index] = NULL;
1455 * tty_reopen() - fast re-open of an open tty
1456 * @tty - the tty to open
1458 * Return 0 on success, -errno on error.
1459 * Re-opens on master ptys are not allowed and return -EIO.
1461 * Locking: Caller must hold tty_lock
1463 static int tty_reopen(struct tty_struct *tty)
1465 struct tty_driver *driver = tty->driver;
1467 if (driver->type == TTY_DRIVER_TYPE_PTY &&
1468 driver->subtype == PTY_TYPE_MASTER)
1474 if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
1479 WARN_ON(!tty->ldisc);
1485 * tty_init_dev - initialise a tty device
1486 * @driver: tty driver we are opening a device on
1487 * @idx: device index
1488 * @ret_tty: returned tty structure
1490 * Prepare a tty device. This may not be a "new" clean device but
1491 * could also be an active device. The pty drivers require special
1492 * handling because of this.
1495 * The function is called under the tty_mutex, which
1496 * protects us from the tty struct or driver itself going away.
1498 * On exit the tty device has the line discipline attached and
1499 * a reference count of 1. If a pair was created for pty/tty use
1500 * and the other was a pty master then it too has a reference count of 1.
1502 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1503 * failed open. The new code protects the open with a mutex, so it's
1504 * really quite straightforward. The mutex locking can probably be
1505 * relaxed for the (most common) case of reopening a tty.
1508 struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
1510 struct tty_struct *tty;
1514 * First time open is complex, especially for PTY devices.
1515 * This code guarantees that either everything succeeds and the
1516 * TTY is ready for operation, or else the table slots are vacated
1517 * and the allocated memory released. (Except that the termios
1518 * and locked termios may be retained.)
1521 if (!try_module_get(driver->owner))
1522 return ERR_PTR(-ENODEV);
1524 tty = alloc_tty_struct(driver, idx);
1527 goto err_module_put;
1531 retval = tty_driver_install_tty(driver, tty);
1536 tty->port = driver->ports[idx];
1538 WARN_RATELIMIT(!tty->port,
1539 "%s: %s driver does not set tty->port. This will crash the kernel later. Fix the driver!\n",
1540 __func__, tty->driver->name);
1542 tty->port->itty = tty;
1545 * Structures all installed ... call the ldisc open routines.
1546 * If we fail here just call release_tty to clean up. No need
1547 * to decrement the use counts, as release_tty doesn't care.
1549 retval = tty_ldisc_setup(tty, tty->link);
1551 goto err_release_tty;
1552 /* Return the tty locked so that it cannot vanish under the caller */
1557 free_tty_struct(tty);
1559 module_put(driver->owner);
1560 return ERR_PTR(retval);
1562 /* call the tty release_tty routine to clean out this slot */
1565 tty_info_ratelimited(tty, "ldisc open failed (%d), clearing slot %d\n",
1567 release_tty(tty, idx);
1568 return ERR_PTR(retval);
1571 void tty_free_termios(struct tty_struct *tty)
1573 struct ktermios *tp;
1574 int idx = tty->index;
1576 /* If the port is going to reset then it has no termios to save */
1577 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1580 /* Stash the termios data */
1581 tp = tty->driver->termios[idx];
1583 tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
1586 tty->driver->termios[idx] = tp;
1590 EXPORT_SYMBOL(tty_free_termios);
1593 * tty_flush_works - flush all works of a tty/pty pair
1594 * @tty: tty device to flush works for (or either end of a pty pair)
1596 * Sync flush all works belonging to @tty (and the 'other' tty).
1598 static void tty_flush_works(struct tty_struct *tty)
1600 flush_work(&tty->SAK_work);
1601 flush_work(&tty->hangup_work);
1603 flush_work(&tty->link->SAK_work);
1604 flush_work(&tty->link->hangup_work);
1609 * release_one_tty - release tty structure memory
1610 * @kref: kref of tty we are obliterating
1612 * Releases memory associated with a tty structure, and clears out the
1613 * driver table slots. This function is called when a device is no longer
1614 * in use. It also gets called when setup of a device fails.
1617 * takes the file list lock internally when working on the list
1618 * of ttys that the driver keeps.
1620 * This method gets called from a work queue so that the driver private
1621 * cleanup ops can sleep (needed for USB at least)
1623 static void release_one_tty(struct work_struct *work)
1625 struct tty_struct *tty =
1626 container_of(work, struct tty_struct, hangup_work);
1627 struct tty_driver *driver = tty->driver;
1628 struct module *owner = driver->owner;
1630 if (tty->ops->cleanup)
1631 tty->ops->cleanup(tty);
1634 tty_driver_kref_put(driver);
1637 spin_lock(&tty_files_lock);
1638 list_del_init(&tty->tty_files);
1639 spin_unlock(&tty_files_lock);
1642 put_pid(tty->session);
1643 free_tty_struct(tty);
1646 static void queue_release_one_tty(struct kref *kref)
1648 struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1650 /* The hangup queue is now free so we can reuse it rather than
1651 waste a chunk of memory for each port */
1652 INIT_WORK(&tty->hangup_work, release_one_tty);
1653 schedule_work(&tty->hangup_work);
1657 * tty_kref_put - release a tty kref
1660 * Release a reference to a tty device and if need be let the kref
1661 * layer destruct the object for us
1664 void tty_kref_put(struct tty_struct *tty)
1667 kref_put(&tty->kref, queue_release_one_tty);
1669 EXPORT_SYMBOL(tty_kref_put);
1672 * release_tty - release tty structure memory
1674 * Release both @tty and a possible linked partner (think pty pair),
1675 * and decrement the refcount of the backing module.
1679 * takes the file list lock internally when working on the list
1680 * of ttys that the driver keeps.
1683 static void release_tty(struct tty_struct *tty, int idx)
1685 /* This should always be true but check for the moment */
1686 WARN_ON(tty->index != idx);
1687 WARN_ON(!mutex_is_locked(&tty_mutex));
1688 if (tty->ops->shutdown)
1689 tty->ops->shutdown(tty);
1690 tty_free_termios(tty);
1691 tty_driver_remove_tty(tty->driver, tty);
1692 tty->port->itty = NULL;
1694 tty->link->port->itty = NULL;
1695 tty_buffer_cancel_work(tty->port);
1697 tty_kref_put(tty->link);
1702 * tty_release_checks - check a tty before real release
1703 * @tty: tty to check
1704 * @o_tty: link of @tty (if any)
1705 * @idx: index of the tty
1707 * Performs some paranoid checking before true release of the @tty.
1708 * This is a no-op unless TTY_PARANOIA_CHECK is defined.
1710 static int tty_release_checks(struct tty_struct *tty, int idx)
1712 #ifdef TTY_PARANOIA_CHECK
1713 if (idx < 0 || idx >= tty->driver->num) {
1714 tty_debug(tty, "bad idx %d\n", idx);
1718 /* not much to check for devpts */
1719 if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)
1722 if (tty != tty->driver->ttys[idx]) {
1723 tty_debug(tty, "bad driver table[%d] = %p\n",
1724 idx, tty->driver->ttys[idx]);
1727 if (tty->driver->other) {
1728 struct tty_struct *o_tty = tty->link;
1730 if (o_tty != tty->driver->other->ttys[idx]) {
1731 tty_debug(tty, "bad other table[%d] = %p\n",
1732 idx, tty->driver->other->ttys[idx]);
1735 if (o_tty->link != tty) {
1736 tty_debug(tty, "bad link = %p\n", o_tty->link);
1745 * tty_release - vfs callback for close
1746 * @inode: inode of tty
1747 * @filp: file pointer for handle to tty
1749 * Called the last time each file handle is closed that references
1750 * this tty. There may however be several such references.
1753 * Takes bkl. See tty_release_dev
1755 * Even releasing the tty structures is a tricky business.. We have
1756 * to be very careful that the structures are all released at the
1757 * same time, as interrupts might otherwise get the wrong pointers.
1759 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1760 * lead to double frees or releasing memory still in use.
1763 int tty_release(struct inode *inode, struct file *filp)
1765 struct tty_struct *tty = file_tty(filp);
1766 struct tty_struct *o_tty = NULL;
1767 int do_sleep, final;
1772 if (tty_paranoia_check(tty, inode, __func__))
1776 check_tty_count(tty, __func__);
1778 __tty_fasync(-1, filp, 0);
1781 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1782 tty->driver->subtype == PTY_TYPE_MASTER)
1785 if (tty_release_checks(tty, idx)) {
1790 tty_debug_hangup(tty, "releasing (count=%d)\n", tty->count);
1792 if (tty->ops->close)
1793 tty->ops->close(tty, filp);
1795 /* If tty is pty master, lock the slave pty (stable lock order) */
1796 tty_lock_slave(o_tty);
1799 * Sanity check: if tty->count is going to zero, there shouldn't be
1800 * any waiters on tty->read_wait or tty->write_wait. We test the
1801 * wait queues and kick everyone out _before_ actually starting to
1802 * close. This ensures that we won't block while releasing the tty
1805 * The test for the o_tty closing is necessary, since the master and
1806 * slave sides may close in any order. If the slave side closes out
1807 * first, its count will be one, since the master side holds an open.
1808 * Thus this test wouldn't be triggered at the time the slave closed,
1814 if (tty->count <= 1) {
1815 if (waitqueue_active(&tty->read_wait)) {
1816 wake_up_poll(&tty->read_wait, POLLIN);
1819 if (waitqueue_active(&tty->write_wait)) {
1820 wake_up_poll(&tty->write_wait, POLLOUT);
1824 if (o_tty && o_tty->count <= 1) {
1825 if (waitqueue_active(&o_tty->read_wait)) {
1826 wake_up_poll(&o_tty->read_wait, POLLIN);
1829 if (waitqueue_active(&o_tty->write_wait)) {
1830 wake_up_poll(&o_tty->write_wait, POLLOUT);
1839 tty_warn(tty, "read/write wait queue active!\n");
1841 schedule_timeout_killable(timeout);
1842 if (timeout < 120 * HZ)
1843 timeout = 2 * timeout + 1;
1845 timeout = MAX_SCHEDULE_TIMEOUT;
1849 if (--o_tty->count < 0) {
1850 tty_warn(tty, "bad slave count (%d)\n", o_tty->count);
1854 if (--tty->count < 0) {
1855 tty_warn(tty, "bad tty->count (%d)\n", tty->count);
1860 * We've decremented tty->count, so we need to remove this file
1861 * descriptor off the tty->tty_files list; this serves two
1863 * - check_tty_count sees the correct number of file descriptors
1864 * associated with this tty.
1865 * - do_tty_hangup no longer sees this file descriptor as
1866 * something that needs to be handled for hangups.
1871 * Perform some housekeeping before deciding whether to return.
1873 * If _either_ side is closing, make sure there aren't any
1874 * processes that still think tty or o_tty is their controlling
1878 read_lock(&tasklist_lock);
1879 session_clear_tty(tty->session);
1881 session_clear_tty(o_tty->session);
1882 read_unlock(&tasklist_lock);
1885 /* check whether both sides are closing ... */
1886 final = !tty->count && !(o_tty && o_tty->count);
1888 tty_unlock_slave(o_tty);
1891 /* At this point, the tty->count == 0 should ensure a dead tty
1892 cannot be re-opened by a racing opener */
1897 tty_debug_hangup(tty, "final close\n");
1899 * Ask the line discipline code to release its structures
1901 tty_ldisc_release(tty);
1903 /* Wait for pending work before tty destruction commmences */
1904 tty_flush_works(tty);
1906 tty_debug_hangup(tty, "freeing structure\n");
1908 * The release_tty function takes care of the details of clearing
1909 * the slots and preserving the termios structure. The tty_unlock_pair
1910 * should be safe as we keep a kref while the tty is locked (so the
1911 * unlock never unlocks a freed tty).
1913 mutex_lock(&tty_mutex);
1914 release_tty(tty, idx);
1915 mutex_unlock(&tty_mutex);
1921 * tty_open_current_tty - get locked tty of current task
1922 * @device: device number
1923 * @filp: file pointer to tty
1924 * @return: locked tty of the current task iff @device is /dev/tty
1926 * Performs a re-open of the current task's controlling tty.
1928 * We cannot return driver and index like for the other nodes because
1929 * devpts will not work then. It expects inodes to be from devpts FS.
1931 static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
1933 struct tty_struct *tty;
1936 if (device != MKDEV(TTYAUX_MAJOR, 0))
1939 tty = get_current_tty();
1941 return ERR_PTR(-ENXIO);
1943 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1946 tty_kref_put(tty); /* safe to drop the kref now */
1948 retval = tty_reopen(tty);
1951 tty = ERR_PTR(retval);
1957 * tty_lookup_driver - lookup a tty driver for a given device file
1958 * @device: device number
1959 * @filp: file pointer to tty
1960 * @noctty: set if the device should not become a controlling tty
1961 * @index: index for the device in the @return driver
1962 * @return: driver for this inode (with increased refcount)
1964 * If @return is not erroneous, the caller is responsible to decrement the
1965 * refcount by tty_driver_kref_put.
1967 * Locking: tty_mutex protects get_tty_driver
1969 static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
1970 int *noctty, int *index)
1972 struct tty_driver *driver;
1976 case MKDEV(TTY_MAJOR, 0): {
1977 extern struct tty_driver *console_driver;
1978 driver = tty_driver_kref_get(console_driver);
1979 *index = fg_console;
1984 case MKDEV(TTYAUX_MAJOR, 1): {
1985 struct tty_driver *console_driver = console_device(index);
1986 if (console_driver) {
1987 driver = tty_driver_kref_get(console_driver);
1989 /* Don't let /dev/console block */
1990 filp->f_flags |= O_NONBLOCK;
1995 return ERR_PTR(-ENODEV);
1998 driver = get_tty_driver(device, index);
2000 return ERR_PTR(-ENODEV);
2007 * tty_open - open a tty device
2008 * @inode: inode of device file
2009 * @filp: file pointer to tty
2011 * tty_open and tty_release keep up the tty count that contains the
2012 * number of opens done on a tty. We cannot use the inode-count, as
2013 * different inodes might point to the same tty.
2015 * Open-counting is needed for pty masters, as well as for keeping
2016 * track of serial lines: DTR is dropped when the last close happens.
2017 * (This is not done solely through tty->count, now. - Ted 1/27/92)
2019 * The termios state of a pty is reset on first open so that
2020 * settings don't persist across reuse.
2022 * Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.
2023 * tty->count should protect the rest.
2024 * ->siglock protects ->signal/->sighand
2026 * Note: the tty_unlock/lock cases without a ref are only safe due to
2030 static int tty_open(struct inode *inode, struct file *filp)
2032 struct tty_struct *tty;
2034 struct tty_driver *driver = NULL;
2036 dev_t device = inode->i_rdev;
2037 unsigned saved_flags = filp->f_flags;
2039 nonseekable_open(inode, filp);
2042 retval = tty_alloc_file(filp);
2046 noctty = filp->f_flags & O_NOCTTY;
2050 tty = tty_open_current_tty(device, filp);
2052 mutex_lock(&tty_mutex);
2053 driver = tty_lookup_driver(device, filp, &noctty, &index);
2054 if (IS_ERR(driver)) {
2055 retval = PTR_ERR(driver);
2059 /* check whether we're reopening an existing tty */
2060 tty = tty_driver_lookup_tty(driver, inode, index);
2062 retval = PTR_ERR(tty);
2067 mutex_unlock(&tty_mutex);
2068 retval = tty_lock_interruptible(tty);
2070 if (retval == -EINTR)
2071 retval = -ERESTARTSYS;
2074 /* safe to drop the kref from tty_driver_lookup_tty() */
2076 retval = tty_reopen(tty);
2079 tty = ERR_PTR(retval);
2081 } else { /* Returns with the tty_lock held for now */
2082 tty = tty_init_dev(driver, index);
2083 mutex_unlock(&tty_mutex);
2086 tty_driver_kref_put(driver);
2090 retval = PTR_ERR(tty);
2091 if (retval != -EAGAIN || signal_pending(current))
2093 tty_free_file(filp);
2098 tty_add_file(tty, filp);
2100 check_tty_count(tty, __func__);
2101 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2102 tty->driver->subtype == PTY_TYPE_MASTER)
2105 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
2108 retval = tty->ops->open(tty, filp);
2111 filp->f_flags = saved_flags;
2114 tty_debug_hangup(tty, "open error %d, releasing\n", retval);
2116 tty_unlock(tty); /* need to call tty_release without BTM */
2117 tty_release(inode, filp);
2118 if (retval != -ERESTARTSYS)
2121 if (signal_pending(current))
2126 * Need to reset f_op in case a hangup happened.
2128 if (tty_hung_up_p(filp))
2129 filp->f_op = &tty_fops;
2132 clear_bit(TTY_HUPPED, &tty->flags);
2135 read_lock(&tasklist_lock);
2136 spin_lock_irq(¤t->sighand->siglock);
2138 current->signal->leader &&
2139 !current->signal->tty &&
2140 tty->session == NULL) {
2142 * Don't let a process that only has write access to the tty
2143 * obtain the privileges associated with having a tty as
2144 * controlling terminal (being able to reopen it with full
2145 * access through /dev/tty, being able to perform pushback).
2146 * Many distributions set the group of all ttys to "tty" and
2147 * grant write-only access to all terminals for setgid tty
2148 * binaries, which should not imply full privileges on all ttys.
2150 * This could theoretically break old code that performs open()
2151 * on a write-only file descriptor. In that case, it might be
2152 * necessary to also permit this if
2153 * inode_permission(inode, MAY_READ) == 0.
2155 if (filp->f_mode & FMODE_READ)
2156 __proc_set_tty(tty);
2158 spin_unlock_irq(¤t->sighand->siglock);
2159 read_unlock(&tasklist_lock);
2163 mutex_unlock(&tty_mutex);
2165 /* after locks to avoid deadlock */
2166 if (!IS_ERR_OR_NULL(driver))
2167 tty_driver_kref_put(driver);
2169 tty_free_file(filp);
2176 * tty_poll - check tty status
2177 * @filp: file being polled
2178 * @wait: poll wait structures to update
2180 * Call the line discipline polling method to obtain the poll
2181 * status of the device.
2183 * Locking: locks called line discipline but ldisc poll method
2184 * may be re-entered freely by other callers.
2187 static unsigned int tty_poll(struct file *filp, poll_table *wait)
2189 struct tty_struct *tty = file_tty(filp);
2190 struct tty_ldisc *ld;
2193 if (tty_paranoia_check(tty, file_inode(filp), "tty_poll"))
2196 ld = tty_ldisc_ref_wait(tty);
2198 ret = ld->ops->poll(tty, filp, wait);
2199 tty_ldisc_deref(ld);
2203 static int __tty_fasync(int fd, struct file *filp, int on)
2205 struct tty_struct *tty = file_tty(filp);
2206 struct tty_ldisc *ldisc;
2207 unsigned long flags;
2210 if (tty_paranoia_check(tty, file_inode(filp), "tty_fasync"))
2213 retval = fasync_helper(fd, filp, on, &tty->fasync);
2217 ldisc = tty_ldisc_ref(tty);
2219 if (ldisc->ops->fasync)
2220 ldisc->ops->fasync(tty, on);
2221 tty_ldisc_deref(ldisc);
2228 spin_lock_irqsave(&tty->ctrl_lock, flags);
2231 type = PIDTYPE_PGID;
2233 pid = task_pid(current);
2237 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2238 __f_setown(filp, pid, type, 0);
2246 static int tty_fasync(int fd, struct file *filp, int on)
2248 struct tty_struct *tty = file_tty(filp);
2252 retval = __tty_fasync(fd, filp, on);
2259 * tiocsti - fake input character
2260 * @tty: tty to fake input into
2261 * @p: pointer to character
2263 * Fake input to a tty device. Does the necessary locking and
2266 * FIXME: does not honour flow control ??
2269 * Called functions take tty_ldiscs_lock
2270 * current->signal->tty check is safe without locks
2272 * FIXME: may race normal receive processing
2275 static int tiocsti(struct tty_struct *tty, char __user *p)
2278 struct tty_ldisc *ld;
2280 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2282 if (get_user(ch, p))
2284 tty_audit_tiocsti(tty, ch);
2285 ld = tty_ldisc_ref_wait(tty);
2286 ld->ops->receive_buf(tty, &ch, &mbz, 1);
2287 tty_ldisc_deref(ld);
2292 * tiocgwinsz - implement window query ioctl
2294 * @arg: user buffer for result
2296 * Copies the kernel idea of the window size into the user buffer.
2298 * Locking: tty->winsize_mutex is taken to ensure the winsize data
2302 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2306 mutex_lock(&tty->winsize_mutex);
2307 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2308 mutex_unlock(&tty->winsize_mutex);
2310 return err ? -EFAULT: 0;
2314 * tty_do_resize - resize event
2315 * @tty: tty being resized
2316 * @rows: rows (character)
2317 * @cols: cols (character)
2319 * Update the termios variables and send the necessary signals to
2320 * peform a terminal resize correctly
2323 int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
2328 mutex_lock(&tty->winsize_mutex);
2329 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
2332 /* Signal the foreground process group */
2333 pgrp = tty_get_pgrp(tty);
2335 kill_pgrp(pgrp, SIGWINCH, 1);
2340 mutex_unlock(&tty->winsize_mutex);
2343 EXPORT_SYMBOL(tty_do_resize);
2346 * tiocswinsz - implement window size set ioctl
2347 * @tty; tty side of tty
2348 * @arg: user buffer for result
2350 * Copies the user idea of the window size to the kernel. Traditionally
2351 * this is just advisory information but for the Linux console it
2352 * actually has driver level meaning and triggers a VC resize.
2355 * Driver dependent. The default do_resize method takes the
2356 * tty termios mutex and ctrl_lock. The console takes its own lock
2357 * then calls into the default method.
2360 static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
2362 struct winsize tmp_ws;
2363 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2366 if (tty->ops->resize)
2367 return tty->ops->resize(tty, &tmp_ws);
2369 return tty_do_resize(tty, &tmp_ws);
2373 * tioccons - allow admin to move logical console
2374 * @file: the file to become console
2376 * Allow the administrator to move the redirected console device
2378 * Locking: uses redirect_lock to guard the redirect information
2381 static int tioccons(struct file *file)
2383 if (!capable(CAP_SYS_ADMIN))
2385 if (file->f_op->write == redirected_tty_write) {
2387 spin_lock(&redirect_lock);
2390 spin_unlock(&redirect_lock);
2395 spin_lock(&redirect_lock);
2397 spin_unlock(&redirect_lock);
2400 redirect = get_file(file);
2401 spin_unlock(&redirect_lock);
2406 * fionbio - non blocking ioctl
2407 * @file: file to set blocking value
2408 * @p: user parameter
2410 * Historical tty interfaces had a blocking control ioctl before
2411 * the generic functionality existed. This piece of history is preserved
2412 * in the expected tty API of posix OS's.
2414 * Locking: none, the open file handle ensures it won't go away.
2417 static int fionbio(struct file *file, int __user *p)
2421 if (get_user(nonblock, p))
2424 spin_lock(&file->f_lock);
2426 file->f_flags |= O_NONBLOCK;
2428 file->f_flags &= ~O_NONBLOCK;
2429 spin_unlock(&file->f_lock);
2434 * tiocsctty - set controlling tty
2435 * @tty: tty structure
2436 * @arg: user argument
2438 * This ioctl is used to manage job control. It permits a session
2439 * leader to set this tty as the controlling tty for the session.
2442 * Takes tty_lock() to serialize proc_set_tty() for this tty
2443 * Takes tasklist_lock internally to walk sessions
2444 * Takes ->siglock() when updating signal->tty
2447 static int tiocsctty(struct tty_struct *tty, struct file *file, int arg)
2452 read_lock(&tasklist_lock);
2454 if (current->signal->leader && (task_session(current) == tty->session))
2458 * The process must be a session leader and
2459 * not have a controlling tty already.
2461 if (!current->signal->leader || current->signal->tty) {
2468 * This tty is already the controlling
2469 * tty for another session group!
2471 if (arg == 1 && capable(CAP_SYS_ADMIN)) {
2475 session_clear_tty(tty->session);
2482 /* See the comment in tty_open(). */
2483 if ((file->f_mode & FMODE_READ) == 0 && !capable(CAP_SYS_ADMIN)) {
2490 read_unlock(&tasklist_lock);
2496 * tty_get_pgrp - return a ref counted pgrp pid
2499 * Returns a refcounted instance of the pid struct for the process
2500 * group controlling the tty.
2503 struct pid *tty_get_pgrp(struct tty_struct *tty)
2505 unsigned long flags;
2508 spin_lock_irqsave(&tty->ctrl_lock, flags);
2509 pgrp = get_pid(tty->pgrp);
2510 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2514 EXPORT_SYMBOL_GPL(tty_get_pgrp);
2517 * This checks not only the pgrp, but falls back on the pid if no
2518 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
2521 * The caller must hold rcu lock or the tasklist lock.
2523 static struct pid *session_of_pgrp(struct pid *pgrp)
2525 struct task_struct *p;
2526 struct pid *sid = NULL;
2528 p = pid_task(pgrp, PIDTYPE_PGID);
2530 p = pid_task(pgrp, PIDTYPE_PID);
2532 sid = task_session(p);
2538 * tiocgpgrp - get process group
2539 * @tty: tty passed by user
2540 * @real_tty: tty side of the tty passed by the user if a pty else the tty
2543 * Obtain the process group of the tty. If there is no process group
2546 * Locking: none. Reference to current->signal->tty is safe.
2549 static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2554 * (tty == real_tty) is a cheap way of
2555 * testing if the tty is NOT a master pty.
2557 if (tty == real_tty && current->signal->tty != real_tty)
2559 pid = tty_get_pgrp(real_tty);
2560 ret = put_user(pid_vnr(pid), p);
2566 * tiocspgrp - attempt to set process group
2567 * @tty: tty passed by user
2568 * @real_tty: tty side device matching tty passed by user
2571 * Set the process group of the tty to the session passed. Only
2572 * permitted where the tty session is our session.
2574 * Locking: RCU, ctrl lock
2577 static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2581 int retval = tty_check_change(real_tty);
2587 if (!current->signal->tty ||
2588 (current->signal->tty != real_tty) ||
2589 (real_tty->session != task_session(current)))
2591 if (get_user(pgrp_nr, p))
2596 pgrp = find_vpid(pgrp_nr);
2601 if (session_of_pgrp(pgrp) != task_session(current))
2604 spin_lock_irq(&tty->ctrl_lock);
2605 put_pid(real_tty->pgrp);
2606 real_tty->pgrp = get_pid(pgrp);
2607 spin_unlock_irq(&tty->ctrl_lock);
2614 * tiocgsid - get session id
2615 * @tty: tty passed by user
2616 * @real_tty: tty side of the tty passed by the user if a pty else the tty
2617 * @p: pointer to returned session id
2619 * Obtain the session id of the tty. If there is no session
2622 * Locking: none. Reference to current->signal->tty is safe.
2625 static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2628 * (tty == real_tty) is a cheap way of
2629 * testing if the tty is NOT a master pty.
2631 if (tty == real_tty && current->signal->tty != real_tty)
2633 if (!real_tty->session)
2635 return put_user(pid_vnr(real_tty->session), p);
2639 * tiocsetd - set line discipline
2641 * @p: pointer to user data
2643 * Set the line discipline according to user request.
2645 * Locking: see tty_set_ldisc, this function is just a helper
2648 static int tiocsetd(struct tty_struct *tty, int __user *p)
2653 if (get_user(ldisc, p))
2656 ret = tty_set_ldisc(tty, ldisc);
2662 * tiocgetd - get line discipline
2664 * @p: pointer to user data
2666 * Retrieves the line discipline id directly from the ldisc.
2668 * Locking: waits for ldisc reference (in case the line discipline
2669 * is changing or the tty is being hungup)
2672 static int tiocgetd(struct tty_struct *tty, int __user *p)
2674 struct tty_ldisc *ld;
2677 ld = tty_ldisc_ref_wait(tty);
2678 ret = put_user(ld->ops->num, p);
2679 tty_ldisc_deref(ld);
2684 * send_break - performed time break
2685 * @tty: device to break on
2686 * @duration: timeout in mS
2688 * Perform a timed break on hardware that lacks its own driver level
2689 * timed break functionality.
2692 * atomic_write_lock serializes
2696 static int send_break(struct tty_struct *tty, unsigned int duration)
2700 if (tty->ops->break_ctl == NULL)
2703 if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2704 retval = tty->ops->break_ctl(tty, duration);
2706 /* Do the work ourselves */
2707 if (tty_write_lock(tty, 0) < 0)
2709 retval = tty->ops->break_ctl(tty, -1);
2712 if (!signal_pending(current))
2713 msleep_interruptible(duration);
2714 retval = tty->ops->break_ctl(tty, 0);
2716 tty_write_unlock(tty);
2717 if (signal_pending(current))
2724 * tty_tiocmget - get modem status
2726 * @file: user file pointer
2727 * @p: pointer to result
2729 * Obtain the modem status bits from the tty driver if the feature
2730 * is supported. Return -EINVAL if it is not available.
2732 * Locking: none (up to the driver)
2735 static int tty_tiocmget(struct tty_struct *tty, int __user *p)
2737 int retval = -EINVAL;
2739 if (tty->ops->tiocmget) {
2740 retval = tty->ops->tiocmget(tty);
2743 retval = put_user(retval, p);
2749 * tty_tiocmset - set modem status
2751 * @cmd: command - clear bits, set bits or set all
2752 * @p: pointer to desired bits
2754 * Set the modem status bits from the tty driver if the feature
2755 * is supported. Return -EINVAL if it is not available.
2757 * Locking: none (up to the driver)
2760 static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
2764 unsigned int set, clear, val;
2766 if (tty->ops->tiocmset == NULL)
2769 retval = get_user(val, p);
2785 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2786 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2787 return tty->ops->tiocmset(tty, set, clear);
2790 static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
2792 int retval = -EINVAL;
2793 struct serial_icounter_struct icount;
2794 memset(&icount, 0, sizeof(icount));
2795 if (tty->ops->get_icount)
2796 retval = tty->ops->get_icount(tty, &icount);
2799 if (copy_to_user(arg, &icount, sizeof(icount)))
2804 static void tty_warn_deprecated_flags(struct serial_struct __user *ss)
2806 static DEFINE_RATELIMIT_STATE(depr_flags,
2807 DEFAULT_RATELIMIT_INTERVAL,
2808 DEFAULT_RATELIMIT_BURST);
2809 char comm[TASK_COMM_LEN];
2812 if (get_user(flags, &ss->flags))
2815 flags &= ASYNC_DEPRECATED;
2817 if (flags && __ratelimit(&depr_flags))
2818 pr_warning("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
2819 __func__, get_task_comm(comm, current), flags);
2823 * if pty, return the slave side (real_tty)
2824 * otherwise, return self
2826 static struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
2828 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2829 tty->driver->subtype == PTY_TYPE_MASTER)
2835 * Split this up, as gcc can choke on it otherwise..
2837 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2839 struct tty_struct *tty = file_tty(file);
2840 struct tty_struct *real_tty;
2841 void __user *p = (void __user *)arg;
2843 struct tty_ldisc *ld;
2845 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2848 real_tty = tty_pair_get_tty(tty);
2851 * Factor out some common prep work
2859 retval = tty_check_change(tty);
2862 if (cmd != TIOCCBRK) {
2863 tty_wait_until_sent(tty, 0);
2864 if (signal_pending(current))
2875 return tiocsti(tty, p);
2877 return tiocgwinsz(real_tty, p);
2879 return tiocswinsz(real_tty, p);
2881 return real_tty != tty ? -EINVAL : tioccons(file);
2883 return fionbio(file, p);
2885 set_bit(TTY_EXCLUSIVE, &tty->flags);
2888 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2892 int excl = test_bit(TTY_EXCLUSIVE, &tty->flags);
2893 return put_user(excl, (int __user *)p);
2896 if (current->signal->tty != tty)
2901 return tiocsctty(real_tty, file, arg);
2903 return tiocgpgrp(tty, real_tty, p);
2905 return tiocspgrp(tty, real_tty, p);
2907 return tiocgsid(tty, real_tty, p);
2909 return tiocgetd(tty, p);
2911 return tiocsetd(tty, p);
2913 if (!capable(CAP_SYS_ADMIN))
2919 unsigned int ret = new_encode_dev(tty_devnum(real_tty));
2920 return put_user(ret, (unsigned int __user *)p);
2925 case TIOCSBRK: /* Turn break on, unconditionally */
2926 if (tty->ops->break_ctl)
2927 return tty->ops->break_ctl(tty, -1);
2929 case TIOCCBRK: /* Turn break off, unconditionally */
2930 if (tty->ops->break_ctl)
2931 return tty->ops->break_ctl(tty, 0);
2933 case TCSBRK: /* SVID version: non-zero arg --> no break */
2934 /* non-zero arg means wait for all output data
2935 * to be sent (performed above) but don't send break.
2936 * This is used by the tcdrain() termios function.
2939 return send_break(tty, 250);
2941 case TCSBRKP: /* support for POSIX tcsendbreak() */
2942 return send_break(tty, arg ? arg*100 : 250);
2945 return tty_tiocmget(tty, p);
2949 return tty_tiocmset(tty, cmd, p);
2951 retval = tty_tiocgicount(tty, p);
2952 /* For the moment allow fall through to the old method */
2953 if (retval != -EINVAL)
2960 /* flush tty buffer and allow ldisc to process ioctl */
2961 tty_buffer_flush(tty, NULL);
2966 tty_warn_deprecated_flags(p);
2969 if (tty->ops->ioctl) {
2970 retval = tty->ops->ioctl(tty, cmd, arg);
2971 if (retval != -ENOIOCTLCMD)
2974 ld = tty_ldisc_ref_wait(tty);
2976 if (ld->ops->ioctl) {
2977 retval = ld->ops->ioctl(tty, file, cmd, arg);
2978 if (retval == -ENOIOCTLCMD)
2981 tty_ldisc_deref(ld);
2985 #ifdef CONFIG_COMPAT
2986 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2989 struct tty_struct *tty = file_tty(file);
2990 struct tty_ldisc *ld;
2991 int retval = -ENOIOCTLCMD;
2993 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2996 if (tty->ops->compat_ioctl) {
2997 retval = tty->ops->compat_ioctl(tty, cmd, arg);
2998 if (retval != -ENOIOCTLCMD)
3002 ld = tty_ldisc_ref_wait(tty);
3003 if (ld->ops->compat_ioctl)
3004 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
3006 retval = n_tty_compat_ioctl_helper(tty, file, cmd, arg);
3007 tty_ldisc_deref(ld);
3013 static int this_tty(const void *t, struct file *file, unsigned fd)
3015 if (likely(file->f_op->read != tty_read))
3017 return file_tty(file) != t ? 0 : fd + 1;
3021 * This implements the "Secure Attention Key" --- the idea is to
3022 * prevent trojan horses by killing all processes associated with this
3023 * tty when the user hits the "Secure Attention Key". Required for
3024 * super-paranoid applications --- see the Orange Book for more details.
3026 * This code could be nicer; ideally it should send a HUP, wait a few
3027 * seconds, then send a INT, and then a KILL signal. But you then
3028 * have to coordinate with the init process, since all processes associated
3029 * with the current tty must be dead before the new getty is allowed
3032 * Now, if it would be correct ;-/ The current code has a nasty hole -
3033 * it doesn't catch files in flight. We may send the descriptor to ourselves
3034 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
3036 * Nasty bug: do_SAK is being called in interrupt context. This can
3037 * deadlock. We punt it up to process context. AKPM - 16Mar2001
3039 void __do_SAK(struct tty_struct *tty)
3044 struct task_struct *g, *p;
3045 struct pid *session;
3050 session = tty->session;
3052 tty_ldisc_flush(tty);
3054 tty_driver_flush_buffer(tty);
3056 read_lock(&tasklist_lock);
3057 /* Kill the entire session */
3058 do_each_pid_task(session, PIDTYPE_SID, p) {
3059 tty_notice(tty, "SAK: killed process %d (%s): by session\n",
3060 task_pid_nr(p), p->comm);
3061 send_sig(SIGKILL, p, 1);
3062 } while_each_pid_task(session, PIDTYPE_SID, p);
3064 /* Now kill any processes that happen to have the tty open */
3065 do_each_thread(g, p) {
3066 if (p->signal->tty == tty) {
3067 tty_notice(tty, "SAK: killed process %d (%s): by controlling tty\n",
3068 task_pid_nr(p), p->comm);
3069 send_sig(SIGKILL, p, 1);
3073 i = iterate_fd(p->files, 0, this_tty, tty);
3075 tty_notice(tty, "SAK: killed process %d (%s): by fd#%d\n",
3076 task_pid_nr(p), p->comm, i - 1);
3077 force_sig(SIGKILL, p);
3080 } while_each_thread(g, p);
3081 read_unlock(&tasklist_lock);
3085 static void do_SAK_work(struct work_struct *work)
3087 struct tty_struct *tty =
3088 container_of(work, struct tty_struct, SAK_work);
3093 * The tq handling here is a little racy - tty->SAK_work may already be queued.
3094 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
3095 * the values which we write to it will be identical to the values which it
3096 * already has. --akpm
3098 void do_SAK(struct tty_struct *tty)
3102 schedule_work(&tty->SAK_work);
3105 EXPORT_SYMBOL(do_SAK);
3107 static int dev_match_devt(struct device *dev, const void *data)
3109 const dev_t *devt = data;
3110 return dev->devt == *devt;
3113 /* Must put_device() after it's unused! */
3114 static struct device *tty_get_device(struct tty_struct *tty)
3116 dev_t devt = tty_devnum(tty);
3117 return class_find_device(tty_class, NULL, &devt, dev_match_devt);
3124 * This subroutine allocates and initializes a tty structure.
3126 * Locking: none - tty in question is not exposed at this point
3129 struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
3131 struct tty_struct *tty;
3133 tty = kzalloc(sizeof(*tty), GFP_KERNEL);
3137 kref_init(&tty->kref);
3138 tty->magic = TTY_MAGIC;
3139 tty_ldisc_init(tty);
3140 tty->session = NULL;
3142 mutex_init(&tty->legacy_mutex);
3143 mutex_init(&tty->throttle_mutex);
3144 init_rwsem(&tty->termios_rwsem);
3145 mutex_init(&tty->winsize_mutex);
3146 init_ldsem(&tty->ldisc_sem);
3147 init_waitqueue_head(&tty->write_wait);
3148 init_waitqueue_head(&tty->read_wait);
3149 INIT_WORK(&tty->hangup_work, do_tty_hangup);
3150 mutex_init(&tty->atomic_write_lock);
3151 spin_lock_init(&tty->ctrl_lock);
3152 spin_lock_init(&tty->flow_lock);
3153 INIT_LIST_HEAD(&tty->tty_files);
3154 INIT_WORK(&tty->SAK_work, do_SAK_work);
3156 tty->driver = driver;
3157 tty->ops = driver->ops;
3159 tty_line_name(driver, idx, tty->name);
3160 tty->dev = tty_get_device(tty);
3166 * tty_put_char - write one character to a tty
3170 * Write one byte to the tty using the provided put_char method
3171 * if present. Returns the number of characters successfully output.
3173 * Note: the specific put_char operation in the driver layer may go
3174 * away soon. Don't call it directly, use this method
3177 int tty_put_char(struct tty_struct *tty, unsigned char ch)
3179 if (tty->ops->put_char)
3180 return tty->ops->put_char(tty, ch);
3181 return tty->ops->write(tty, &ch, 1);
3183 EXPORT_SYMBOL_GPL(tty_put_char);
3185 struct class *tty_class;
3187 static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
3188 unsigned int index, unsigned int count)
3192 /* init here, since reused cdevs cause crashes */
3193 driver->cdevs[index] = cdev_alloc();
3194 if (!driver->cdevs[index])
3196 driver->cdevs[index]->ops = &tty_fops;
3197 driver->cdevs[index]->owner = driver->owner;
3198 err = cdev_add(driver->cdevs[index], dev, count);
3200 kobject_put(&driver->cdevs[index]->kobj);
3205 * tty_register_device - register a tty device
3206 * @driver: the tty driver that describes the tty device
3207 * @index: the index in the tty driver for this tty device
3208 * @device: a struct device that is associated with this tty device.
3209 * This field is optional, if there is no known struct device
3210 * for this tty device it can be set to NULL safely.
3212 * Returns a pointer to the struct device for this tty device
3213 * (or ERR_PTR(-EFOO) on error).
3215 * This call is required to be made to register an individual tty device
3216 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3217 * that bit is not set, this function should not be called by a tty
3223 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
3224 struct device *device)
3226 return tty_register_device_attr(driver, index, device, NULL, NULL);
3228 EXPORT_SYMBOL(tty_register_device);
3230 static void tty_device_create_release(struct device *dev)
3232 dev_dbg(dev, "releasing...\n");
3237 * tty_register_device_attr - register a tty device
3238 * @driver: the tty driver that describes the tty device
3239 * @index: the index in the tty driver for this tty device
3240 * @device: a struct device that is associated with this tty device.
3241 * This field is optional, if there is no known struct device
3242 * for this tty device it can be set to NULL safely.
3243 * @drvdata: Driver data to be set to device.
3244 * @attr_grp: Attribute group to be set on device.
3246 * Returns a pointer to the struct device for this tty device
3247 * (or ERR_PTR(-EFOO) on error).
3249 * This call is required to be made to register an individual tty device
3250 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3251 * that bit is not set, this function should not be called by a tty
3256 struct device *tty_register_device_attr(struct tty_driver *driver,
3257 unsigned index, struct device *device,
3259 const struct attribute_group **attr_grp)
3262 dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
3263 struct device *dev = NULL;
3264 int retval = -ENODEV;
3267 if (index >= driver->num) {
3268 pr_err("%s: Attempt to register invalid tty line number (%d)\n",
3269 driver->name, index);
3270 return ERR_PTR(-EINVAL);
3273 if (driver->type == TTY_DRIVER_TYPE_PTY)
3274 pty_line_name(driver, index, name);
3276 tty_line_name(driver, index, name);
3278 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3279 retval = tty_cdev_add(driver, devt, index, 1);
3285 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
3292 dev->class = tty_class;
3293 dev->parent = device;
3294 dev->release = tty_device_create_release;
3295 dev_set_name(dev, "%s", name);
3296 dev->groups = attr_grp;
3297 dev_set_drvdata(dev, drvdata);
3299 retval = device_register(dev);
3308 cdev_del(driver->cdevs[index]);
3309 driver->cdevs[index] = NULL;
3311 return ERR_PTR(retval);
3313 EXPORT_SYMBOL_GPL(tty_register_device_attr);
3316 * tty_unregister_device - unregister a tty device
3317 * @driver: the tty driver that describes the tty device
3318 * @index: the index in the tty driver for this tty device
3320 * If a tty device is registered with a call to tty_register_device() then
3321 * this function must be called when the tty device is gone.
3326 void tty_unregister_device(struct tty_driver *driver, unsigned index)
3328 device_destroy(tty_class,
3329 MKDEV(driver->major, driver->minor_start) + index);
3330 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3331 cdev_del(driver->cdevs[index]);
3332 driver->cdevs[index] = NULL;
3335 EXPORT_SYMBOL(tty_unregister_device);
3338 * __tty_alloc_driver -- allocate tty driver
3339 * @lines: count of lines this driver can handle at most
3340 * @owner: module which is repsonsible for this driver
3341 * @flags: some of TTY_DRIVER_* flags, will be set in driver->flags
3343 * This should not be called directly, some of the provided macros should be
3344 * used instead. Use IS_ERR and friends on @retval.
3346 struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
3347 unsigned long flags)
3349 struct tty_driver *driver;
3350 unsigned int cdevs = 1;
3353 if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
3354 return ERR_PTR(-EINVAL);
3356 driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
3358 return ERR_PTR(-ENOMEM);
3360 kref_init(&driver->kref);
3361 driver->magic = TTY_DRIVER_MAGIC;
3362 driver->num = lines;
3363 driver->owner = owner;
3364 driver->flags = flags;
3366 if (!(flags & TTY_DRIVER_DEVPTS_MEM)) {
3367 driver->ttys = kcalloc(lines, sizeof(*driver->ttys),
3369 driver->termios = kcalloc(lines, sizeof(*driver->termios),
3371 if (!driver->ttys || !driver->termios) {
3377 if (!(flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3378 driver->ports = kcalloc(lines, sizeof(*driver->ports),
3380 if (!driver->ports) {
3387 driver->cdevs = kcalloc(cdevs, sizeof(*driver->cdevs), GFP_KERNEL);
3388 if (!driver->cdevs) {
3395 kfree(driver->ports);
3396 kfree(driver->ttys);
3397 kfree(driver->termios);
3398 kfree(driver->cdevs);
3400 return ERR_PTR(err);
3402 EXPORT_SYMBOL(__tty_alloc_driver);
3404 static void destruct_tty_driver(struct kref *kref)
3406 struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
3408 struct ktermios *tp;
3410 if (driver->flags & TTY_DRIVER_INSTALLED) {
3412 * Free the termios and termios_locked structures because
3413 * we don't want to get memory leaks when modular tty
3414 * drivers are removed from the kernel.
3416 for (i = 0; i < driver->num; i++) {
3417 tp = driver->termios[i];
3419 driver->termios[i] = NULL;
3422 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3423 tty_unregister_device(driver, i);
3425 proc_tty_unregister_driver(driver);
3426 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
3427 cdev_del(driver->cdevs[0]);
3429 kfree(driver->cdevs);
3430 kfree(driver->ports);
3431 kfree(driver->termios);
3432 kfree(driver->ttys);
3436 void tty_driver_kref_put(struct tty_driver *driver)
3438 kref_put(&driver->kref, destruct_tty_driver);
3440 EXPORT_SYMBOL(tty_driver_kref_put);
3442 void tty_set_operations(struct tty_driver *driver,
3443 const struct tty_operations *op)
3447 EXPORT_SYMBOL(tty_set_operations);
3449 void put_tty_driver(struct tty_driver *d)
3451 tty_driver_kref_put(d);
3453 EXPORT_SYMBOL(put_tty_driver);
3456 * Called by a tty driver to register itself.
3458 int tty_register_driver(struct tty_driver *driver)
3465 if (!driver->major) {
3466 error = alloc_chrdev_region(&dev, driver->minor_start,
3467 driver->num, driver->name);
3469 driver->major = MAJOR(dev);
3470 driver->minor_start = MINOR(dev);
3473 dev = MKDEV(driver->major, driver->minor_start);
3474 error = register_chrdev_region(dev, driver->num, driver->name);
3479 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) {
3480 error = tty_cdev_add(driver, dev, 0, driver->num);
3482 goto err_unreg_char;
3485 mutex_lock(&tty_mutex);
3486 list_add(&driver->tty_drivers, &tty_drivers);
3487 mutex_unlock(&tty_mutex);
3489 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
3490 for (i = 0; i < driver->num; i++) {
3491 d = tty_register_device(driver, i, NULL);
3494 goto err_unreg_devs;
3498 proc_tty_register_driver(driver);
3499 driver->flags |= TTY_DRIVER_INSTALLED;
3503 for (i--; i >= 0; i--)
3504 tty_unregister_device(driver, i);
3506 mutex_lock(&tty_mutex);
3507 list_del(&driver->tty_drivers);
3508 mutex_unlock(&tty_mutex);
3511 unregister_chrdev_region(dev, driver->num);
3515 EXPORT_SYMBOL(tty_register_driver);
3518 * Called by a tty driver to unregister itself.
3520 int tty_unregister_driver(struct tty_driver *driver)
3524 if (driver->refcount)
3527 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3529 mutex_lock(&tty_mutex);
3530 list_del(&driver->tty_drivers);
3531 mutex_unlock(&tty_mutex);
3535 EXPORT_SYMBOL(tty_unregister_driver);
3537 dev_t tty_devnum(struct tty_struct *tty)
3539 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3541 EXPORT_SYMBOL(tty_devnum);
3543 void tty_default_fops(struct file_operations *fops)
3549 * Initialize the console device. This is called *early*, so
3550 * we can't necessarily depend on lots of kernel help here.
3551 * Just do some early initializations, and do the complex setup
3554 void __init console_init(void)
3558 /* Setup the default TTY line discipline. */
3562 * set up the console device so that later boot sequences can
3563 * inform about problems etc..
3565 call = __con_initcall_start;
3566 while (call < __con_initcall_end) {
3572 static char *tty_devnode(struct device *dev, umode_t *mode)
3576 if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
3577 dev->devt == MKDEV(TTYAUX_MAJOR, 2))
3582 static int __init tty_class_init(void)
3584 tty_class = class_create(THIS_MODULE, "tty");
3585 if (IS_ERR(tty_class))
3586 return PTR_ERR(tty_class);
3587 tty_class->devnode = tty_devnode;
3591 postcore_initcall(tty_class_init);
3593 /* 3/2004 jmc: why do these devices exist? */
3594 static struct cdev tty_cdev, console_cdev;
3596 static ssize_t show_cons_active(struct device *dev,
3597 struct device_attribute *attr, char *buf)
3599 struct console *cs[16];
3605 for_each_console(c) {
3610 if ((c->flags & CON_ENABLED) == 0)
3613 if (i >= ARRAY_SIZE(cs))
3617 int index = cs[i]->index;
3618 struct tty_driver *drv = cs[i]->device(cs[i], &index);
3620 /* don't resolve tty0 as some programs depend on it */
3621 if (drv && (cs[i]->index > 0 || drv->major != TTY_MAJOR))
3622 count += tty_line_name(drv, index, buf + count);
3624 count += sprintf(buf + count, "%s%d",
3625 cs[i]->name, cs[i]->index);
3627 count += sprintf(buf + count, "%c", i ? ' ':'\n');
3633 static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
3635 static struct attribute *cons_dev_attrs[] = {
3636 &dev_attr_active.attr,
3640 ATTRIBUTE_GROUPS(cons_dev);
3642 static struct device *consdev;
3644 void console_sysfs_notify(void)
3647 sysfs_notify(&consdev->kobj, NULL, "active");
3651 * Ok, now we can initialize the rest of the tty devices and can count
3652 * on memory allocations, interrupts etc..
3654 int __init tty_init(void)
3656 cdev_init(&tty_cdev, &tty_fops);
3657 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3658 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3659 panic("Couldn't register /dev/tty driver\n");
3660 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
3662 cdev_init(&console_cdev, &console_fops);
3663 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3664 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3665 panic("Couldn't register /dev/console driver\n");
3666 consdev = device_create_with_groups(tty_class, NULL,
3667 MKDEV(TTYAUX_MAJOR, 1), NULL,
3668 cons_dev_groups, "console");
3669 if (IS_ERR(consdev))
3673 vty_init(&console_fops);