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 put_device(tty->dev);
176 kfree(tty->write_buf);
177 tty->magic = 0xDEADDEAD;
181 static inline struct tty_struct *file_tty(struct file *file)
183 return ((struct tty_file_private *)file->private_data)->tty;
186 int tty_alloc_file(struct file *file)
188 struct tty_file_private *priv;
190 priv = kmalloc(sizeof(*priv), GFP_KERNEL);
194 file->private_data = priv;
199 /* Associate a new file with the tty structure */
200 void tty_add_file(struct tty_struct *tty, struct file *file)
202 struct tty_file_private *priv = file->private_data;
207 spin_lock(&tty_files_lock);
208 list_add(&priv->list, &tty->tty_files);
209 spin_unlock(&tty_files_lock);
213 * tty_free_file - free file->private_data
215 * This shall be used only for fail path handling when tty_add_file was not
218 void tty_free_file(struct file *file)
220 struct tty_file_private *priv = file->private_data;
222 file->private_data = NULL;
226 /* Delete file from its tty */
227 static void tty_del_file(struct file *file)
229 struct tty_file_private *priv = file->private_data;
231 spin_lock(&tty_files_lock);
232 list_del(&priv->list);
233 spin_unlock(&tty_files_lock);
238 #define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base)
241 * tty_name - return tty naming
242 * @tty: tty structure
244 * Convert a tty structure into a name. The name reflects the kernel
245 * naming policy and if udev is in use may not reflect user space
250 const char *tty_name(const struct tty_struct *tty)
252 if (!tty) /* Hmm. NULL pointer. That's fun. */
257 EXPORT_SYMBOL(tty_name);
259 int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
262 #ifdef TTY_PARANOIA_CHECK
265 "null TTY for (%d:%d) in %s\n",
266 imajor(inode), iminor(inode), routine);
269 if (tty->magic != TTY_MAGIC) {
271 "bad magic number for tty struct (%d:%d) in %s\n",
272 imajor(inode), iminor(inode), routine);
279 /* Caller must hold tty_lock */
280 static int check_tty_count(struct tty_struct *tty, const char *routine)
282 #ifdef CHECK_TTY_COUNT
286 spin_lock(&tty_files_lock);
287 list_for_each(p, &tty->tty_files) {
290 spin_unlock(&tty_files_lock);
291 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
292 tty->driver->subtype == PTY_TYPE_SLAVE &&
293 tty->link && tty->link->count)
295 if (tty->count != count) {
296 printk(KERN_WARNING "Warning: dev (%s) tty->count(%d) "
297 "!= #fd's(%d) in %s\n",
298 tty->name, tty->count, count, routine);
306 * get_tty_driver - find device of a tty
307 * @dev_t: device identifier
308 * @index: returns the index of the tty
310 * This routine returns a tty driver structure, given a device number
311 * and also passes back the index number.
313 * Locking: caller must hold tty_mutex
316 static struct tty_driver *get_tty_driver(dev_t device, int *index)
318 struct tty_driver *p;
320 list_for_each_entry(p, &tty_drivers, tty_drivers) {
321 dev_t base = MKDEV(p->major, p->minor_start);
322 if (device < base || device >= base + p->num)
324 *index = device - base;
325 return tty_driver_kref_get(p);
330 #ifdef CONFIG_CONSOLE_POLL
333 * tty_find_polling_driver - find device of a polled tty
334 * @name: name string to match
335 * @line: pointer to resulting tty line nr
337 * This routine returns a tty driver structure, given a name
338 * and the condition that the tty driver is capable of polled
341 struct tty_driver *tty_find_polling_driver(char *name, int *line)
343 struct tty_driver *p, *res = NULL;
348 for (str = name; *str; str++)
349 if ((*str >= '0' && *str <= '9') || *str == ',')
355 tty_line = simple_strtoul(str, &str, 10);
357 mutex_lock(&tty_mutex);
358 /* Search through the tty devices to look for a match */
359 list_for_each_entry(p, &tty_drivers, tty_drivers) {
360 if (strncmp(name, p->name, len) != 0)
368 if (tty_line >= 0 && tty_line < p->num && p->ops &&
369 p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) {
370 res = tty_driver_kref_get(p);
375 mutex_unlock(&tty_mutex);
379 EXPORT_SYMBOL_GPL(tty_find_polling_driver);
383 * tty_check_change - check for POSIX terminal changes
386 * If we try to write to, or set the state of, a terminal and we're
387 * not in the foreground, send a SIGTTOU. If the signal is blocked or
388 * ignored, go ahead and perform the operation. (POSIX 7.2)
393 int tty_check_change(struct tty_struct *tty)
399 if (current->signal->tty != tty)
403 pgrp = task_pgrp(current);
405 spin_lock_irqsave(&tty->ctrl_lock, flags);
408 printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");
411 if (pgrp == tty->pgrp)
413 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
415 if (is_ignored(SIGTTOU))
417 if (is_current_pgrp_orphaned()) {
421 kill_pgrp(pgrp, SIGTTOU, 1);
423 set_thread_flag(TIF_SIGPENDING);
427 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
433 EXPORT_SYMBOL(tty_check_change);
435 static ssize_t hung_up_tty_read(struct file *file, char __user *buf,
436 size_t count, loff_t *ppos)
441 static ssize_t hung_up_tty_write(struct file *file, const char __user *buf,
442 size_t count, loff_t *ppos)
447 /* No kernel lock held - none needed ;) */
448 static unsigned int hung_up_tty_poll(struct file *filp, poll_table *wait)
450 return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM;
453 static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
456 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
459 static long hung_up_tty_compat_ioctl(struct file *file,
460 unsigned int cmd, unsigned long arg)
462 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
465 static const struct file_operations tty_fops = {
470 .unlocked_ioctl = tty_ioctl,
471 .compat_ioctl = tty_compat_ioctl,
473 .release = tty_release,
474 .fasync = tty_fasync,
477 static const struct file_operations console_fops = {
480 .write = redirected_tty_write,
482 .unlocked_ioctl = tty_ioctl,
483 .compat_ioctl = tty_compat_ioctl,
485 .release = tty_release,
486 .fasync = tty_fasync,
489 static const struct file_operations hung_up_tty_fops = {
491 .read = hung_up_tty_read,
492 .write = hung_up_tty_write,
493 .poll = hung_up_tty_poll,
494 .unlocked_ioctl = hung_up_tty_ioctl,
495 .compat_ioctl = hung_up_tty_compat_ioctl,
496 .release = tty_release,
499 static DEFINE_SPINLOCK(redirect_lock);
500 static struct file *redirect;
503 void proc_clear_tty(struct task_struct *p)
506 struct tty_struct *tty;
507 spin_lock_irqsave(&p->sighand->siglock, flags);
508 tty = p->signal->tty;
509 p->signal->tty = NULL;
510 spin_unlock_irqrestore(&p->sighand->siglock, flags);
515 * proc_set_tty - set the controlling terminal
517 * Only callable by the session leader and only if it does not already have
518 * a controlling terminal.
520 * Caller must hold: tty_lock()
521 * a readlock on tasklist_lock
524 static void __proc_set_tty(struct tty_struct *tty)
528 spin_lock_irqsave(&tty->ctrl_lock, flags);
530 * The session and fg pgrp references will be non-NULL if
531 * tiocsctty() is stealing the controlling tty
533 put_pid(tty->session);
535 tty->pgrp = get_pid(task_pgrp(current));
536 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
537 tty->session = get_pid(task_session(current));
538 if (current->signal->tty) {
539 tty_debug(tty, "current tty %s not NULL!!\n",
540 current->signal->tty->name);
541 tty_kref_put(current->signal->tty);
543 put_pid(current->signal->tty_old_pgrp);
544 current->signal->tty = tty_kref_get(tty);
545 current->signal->tty_old_pgrp = NULL;
548 static void proc_set_tty(struct tty_struct *tty)
550 spin_lock_irq(¤t->sighand->siglock);
552 spin_unlock_irq(¤t->sighand->siglock);
555 struct tty_struct *get_current_tty(void)
557 struct tty_struct *tty;
560 spin_lock_irqsave(¤t->sighand->siglock, flags);
561 tty = tty_kref_get(current->signal->tty);
562 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
565 EXPORT_SYMBOL_GPL(get_current_tty);
567 static void session_clear_tty(struct pid *session)
569 struct task_struct *p;
570 do_each_pid_task(session, PIDTYPE_SID, p) {
572 } while_each_pid_task(session, PIDTYPE_SID, p);
576 * tty_wakeup - request more data
579 * Internal and external helper for wakeups of tty. This function
580 * informs the line discipline if present that the driver is ready
581 * to receive more output data.
584 void tty_wakeup(struct tty_struct *tty)
586 struct tty_ldisc *ld;
588 if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
589 ld = tty_ldisc_ref(tty);
591 if (ld->ops->write_wakeup)
592 ld->ops->write_wakeup(tty);
596 wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
599 EXPORT_SYMBOL_GPL(tty_wakeup);
602 * tty_signal_session_leader - sends SIGHUP to session leader
603 * @tty controlling tty
604 * @exit_session if non-zero, signal all foreground group processes
606 * Send SIGHUP and SIGCONT to the session leader and its process group.
607 * Optionally, signal all processes in the foreground process group.
609 * Returns the number of processes in the session with this tty
610 * as their controlling terminal. This value is used to drop
611 * tty references for those processes.
613 static int tty_signal_session_leader(struct tty_struct *tty, int exit_session)
615 struct task_struct *p;
617 struct pid *tty_pgrp = NULL;
619 read_lock(&tasklist_lock);
621 do_each_pid_task(tty->session, PIDTYPE_SID, p) {
622 spin_lock_irq(&p->sighand->siglock);
623 if (p->signal->tty == tty) {
624 p->signal->tty = NULL;
625 /* We defer the dereferences outside fo
629 if (!p->signal->leader) {
630 spin_unlock_irq(&p->sighand->siglock);
633 __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
634 __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
635 put_pid(p->signal->tty_old_pgrp); /* A noop */
636 spin_lock(&tty->ctrl_lock);
637 tty_pgrp = get_pid(tty->pgrp);
639 p->signal->tty_old_pgrp = get_pid(tty->pgrp);
640 spin_unlock(&tty->ctrl_lock);
641 spin_unlock_irq(&p->sighand->siglock);
642 } while_each_pid_task(tty->session, PIDTYPE_SID, p);
644 read_unlock(&tasklist_lock);
648 kill_pgrp(tty_pgrp, SIGHUP, exit_session);
656 * __tty_hangup - actual handler for hangup events
659 * This can be called by a "kworker" kernel thread. That is process
660 * synchronous but doesn't hold any locks, so we need to make sure we
661 * have the appropriate locks for what we're doing.
663 * The hangup event clears any pending redirections onto the hung up
664 * device. It ensures future writes will error and it does the needed
665 * line discipline hangup and signal delivery. The tty object itself
670 * redirect lock for undoing redirection
671 * file list lock for manipulating list of ttys
672 * tty_ldiscs_lock from called functions
673 * termios_rwsem resetting termios data
674 * tasklist_lock to walk task list for hangup event
675 * ->siglock to protect ->signal/->sighand
677 static void __tty_hangup(struct tty_struct *tty, int exit_session)
679 struct file *cons_filp = NULL;
680 struct file *filp, *f = NULL;
681 struct tty_file_private *priv;
682 int closecount = 0, n;
689 spin_lock(&redirect_lock);
690 if (redirect && file_tty(redirect) == tty) {
694 spin_unlock(&redirect_lock);
698 if (test_bit(TTY_HUPPED, &tty->flags)) {
703 /* inuse_filps is protected by the single tty lock,
704 this really needs to change if we want to flush the
705 workqueue with the lock held */
706 check_tty_count(tty, "tty_hangup");
708 spin_lock(&tty_files_lock);
709 /* This breaks for file handles being sent over AF_UNIX sockets ? */
710 list_for_each_entry(priv, &tty->tty_files, list) {
712 if (filp->f_op->write == redirected_tty_write)
714 if (filp->f_op->write != tty_write)
717 __tty_fasync(-1, filp, 0); /* can't block */
718 filp->f_op = &hung_up_tty_fops;
720 spin_unlock(&tty_files_lock);
722 refs = tty_signal_session_leader(tty, exit_session);
723 /* Account for the p->signal references we killed */
727 tty_ldisc_hangup(tty);
729 spin_lock_irq(&tty->ctrl_lock);
730 clear_bit(TTY_THROTTLED, &tty->flags);
731 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
732 put_pid(tty->session);
736 tty->ctrl_status = 0;
737 spin_unlock_irq(&tty->ctrl_lock);
740 * If one of the devices matches a console pointer, we
741 * cannot just call hangup() because that will cause
742 * tty->count and state->count to go out of sync.
743 * So we just call close() the right number of times.
747 for (n = 0; n < closecount; n++)
748 tty->ops->close(tty, cons_filp);
749 } else if (tty->ops->hangup)
750 tty->ops->hangup(tty);
752 * We don't want to have driver/ldisc interactions beyond
753 * the ones we did here. The driver layer expects no
754 * calls after ->hangup() from the ldisc side. However we
755 * can't yet guarantee all that.
757 set_bit(TTY_HUPPED, &tty->flags);
764 static void do_tty_hangup(struct work_struct *work)
766 struct tty_struct *tty =
767 container_of(work, struct tty_struct, hangup_work);
769 __tty_hangup(tty, 0);
773 * tty_hangup - trigger a hangup event
774 * @tty: tty to hangup
776 * A carrier loss (virtual or otherwise) has occurred on this like
777 * schedule a hangup sequence to run after this event.
780 void tty_hangup(struct tty_struct *tty)
782 tty_debug_hangup(tty, "\n");
783 schedule_work(&tty->hangup_work);
786 EXPORT_SYMBOL(tty_hangup);
789 * tty_vhangup - process vhangup
790 * @tty: tty to hangup
792 * The user has asked via system call for the terminal to be hung up.
793 * We do this synchronously so that when the syscall returns the process
794 * is complete. That guarantee is necessary for security reasons.
797 void tty_vhangup(struct tty_struct *tty)
799 tty_debug_hangup(tty, "\n");
800 __tty_hangup(tty, 0);
803 EXPORT_SYMBOL(tty_vhangup);
807 * tty_vhangup_self - process vhangup for own ctty
809 * Perform a vhangup on the current controlling tty
812 void tty_vhangup_self(void)
814 struct tty_struct *tty;
816 tty = get_current_tty();
824 * tty_vhangup_session - hangup session leader exit
825 * @tty: tty to hangup
827 * The session leader is exiting and hanging up its controlling terminal.
828 * Every process in the foreground process group is signalled SIGHUP.
830 * We do this synchronously so that when the syscall returns the process
831 * is complete. That guarantee is necessary for security reasons.
834 static void tty_vhangup_session(struct tty_struct *tty)
836 tty_debug_hangup(tty, "\n");
837 __tty_hangup(tty, 1);
841 * tty_hung_up_p - was tty hung up
842 * @filp: file pointer of tty
844 * Return true if the tty has been subject to a vhangup or a carrier
848 int tty_hung_up_p(struct file *filp)
850 return (filp->f_op == &hung_up_tty_fops);
853 EXPORT_SYMBOL(tty_hung_up_p);
856 * disassociate_ctty - disconnect controlling tty
857 * @on_exit: true if exiting so need to "hang up" the session
859 * This function is typically called only by the session leader, when
860 * it wants to disassociate itself from its controlling tty.
862 * It performs the following functions:
863 * (1) Sends a SIGHUP and SIGCONT to the foreground process group
864 * (2) Clears the tty from being controlling the session
865 * (3) Clears the controlling tty for all processes in the
868 * The argument on_exit is set to 1 if called when a process is
869 * exiting; it is 0 if called by the ioctl TIOCNOTTY.
872 * BTM is taken for hysterical raisins, and held when
873 * called from no_tty().
874 * tty_mutex is taken to protect tty
875 * ->siglock is taken to protect ->signal/->sighand
876 * tasklist_lock is taken to walk process list for sessions
877 * ->siglock is taken to protect ->signal/->sighand
880 void disassociate_ctty(int on_exit)
882 struct tty_struct *tty;
884 if (!current->signal->leader)
887 tty = get_current_tty();
889 if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY) {
890 tty_vhangup_session(tty);
892 struct pid *tty_pgrp = tty_get_pgrp(tty);
894 kill_pgrp(tty_pgrp, SIGHUP, on_exit);
896 kill_pgrp(tty_pgrp, SIGCONT, on_exit);
902 } else if (on_exit) {
903 struct pid *old_pgrp;
904 spin_lock_irq(¤t->sighand->siglock);
905 old_pgrp = current->signal->tty_old_pgrp;
906 current->signal->tty_old_pgrp = NULL;
907 spin_unlock_irq(¤t->sighand->siglock);
909 kill_pgrp(old_pgrp, SIGHUP, on_exit);
910 kill_pgrp(old_pgrp, SIGCONT, on_exit);
916 spin_lock_irq(¤t->sighand->siglock);
917 put_pid(current->signal->tty_old_pgrp);
918 current->signal->tty_old_pgrp = NULL;
920 tty = tty_kref_get(current->signal->tty);
923 spin_lock_irqsave(&tty->ctrl_lock, flags);
924 put_pid(tty->session);
928 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
931 tty_debug_hangup(tty, "no current tty\n");
933 spin_unlock_irq(¤t->sighand->siglock);
934 /* Now clear signal->tty under the lock */
935 read_lock(&tasklist_lock);
936 session_clear_tty(task_session(current));
937 read_unlock(&tasklist_lock);
942 * no_tty - Ensure the current process does not have a controlling tty
946 /* FIXME: Review locking here. The tty_lock never covered any race
947 between a new association and proc_clear_tty but possible we need
948 to protect against this anyway */
949 struct task_struct *tsk = current;
950 disassociate_ctty(0);
956 * stop_tty - propagate flow control
959 * Perform flow control to the driver. May be called
960 * on an already stopped device and will not re-call the driver
963 * This functionality is used by both the line disciplines for
964 * halting incoming flow and by the driver. It may therefore be
965 * called from any context, may be under the tty atomic_write_lock
972 void __stop_tty(struct tty_struct *tty)
981 void stop_tty(struct tty_struct *tty)
985 spin_lock_irqsave(&tty->flow_lock, flags);
987 spin_unlock_irqrestore(&tty->flow_lock, flags);
989 EXPORT_SYMBOL(stop_tty);
992 * start_tty - propagate flow control
995 * Start a tty that has been stopped if at all possible. If this
996 * tty was previous stopped and is now being started, the driver
997 * start method is invoked and the line discipline woken.
1003 void __start_tty(struct tty_struct *tty)
1005 if (!tty->stopped || tty->flow_stopped)
1008 if (tty->ops->start)
1009 tty->ops->start(tty);
1013 void start_tty(struct tty_struct *tty)
1015 unsigned long flags;
1017 spin_lock_irqsave(&tty->flow_lock, flags);
1019 spin_unlock_irqrestore(&tty->flow_lock, flags);
1021 EXPORT_SYMBOL(start_tty);
1023 static void tty_update_time(struct timespec *time)
1025 unsigned long sec = get_seconds();
1028 * We only care if the two values differ in anything other than the
1029 * lower three bits (i.e every 8 seconds). If so, then we can update
1030 * the time of the tty device, otherwise it could be construded as a
1031 * security leak to let userspace know the exact timing of the tty.
1033 if ((sec ^ time->tv_sec) & ~7)
1038 * tty_read - read method for tty device files
1039 * @file: pointer to tty file
1041 * @count: size of user buffer
1044 * Perform the read system call function on this terminal device. Checks
1045 * for hung up devices before calling the line discipline method.
1048 * Locks the line discipline internally while needed. Multiple
1049 * read calls may be outstanding in parallel.
1052 static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
1056 struct inode *inode = file_inode(file);
1057 struct tty_struct *tty = file_tty(file);
1058 struct tty_ldisc *ld;
1060 if (tty_paranoia_check(tty, inode, "tty_read"))
1062 if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags)))
1065 /* We want to wait for the line discipline to sort out in this
1067 ld = tty_ldisc_ref_wait(tty);
1069 i = ld->ops->read(tty, file, buf, count);
1072 tty_ldisc_deref(ld);
1075 tty_update_time(&inode->i_atime);
1080 static void tty_write_unlock(struct tty_struct *tty)
1082 mutex_unlock(&tty->atomic_write_lock);
1083 wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
1086 static int tty_write_lock(struct tty_struct *tty, int ndelay)
1088 if (!mutex_trylock(&tty->atomic_write_lock)) {
1091 if (mutex_lock_interruptible(&tty->atomic_write_lock))
1092 return -ERESTARTSYS;
1098 * Split writes up in sane blocksizes to avoid
1099 * denial-of-service type attacks
1101 static inline ssize_t do_tty_write(
1102 ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
1103 struct tty_struct *tty,
1105 const char __user *buf,
1108 ssize_t ret, written = 0;
1111 ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
1116 * We chunk up writes into a temporary buffer. This
1117 * simplifies low-level drivers immensely, since they
1118 * don't have locking issues and user mode accesses.
1120 * But if TTY_NO_WRITE_SPLIT is set, we should use a
1123 * The default chunk-size is 2kB, because the NTTY
1124 * layer has problems with bigger chunks. It will
1125 * claim to be able to handle more characters than
1128 * FIXME: This can probably go away now except that 64K chunks
1129 * are too likely to fail unless switched to vmalloc...
1132 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
1137 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
1138 if (tty->write_cnt < chunk) {
1139 unsigned char *buf_chunk;
1144 buf_chunk = kmalloc(chunk, GFP_KERNEL);
1149 kfree(tty->write_buf);
1150 tty->write_cnt = chunk;
1151 tty->write_buf = buf_chunk;
1154 /* Do the write .. */
1156 size_t size = count;
1160 if (copy_from_user(tty->write_buf, buf, size))
1162 ret = write(tty, file, tty->write_buf, size);
1171 if (signal_pending(current))
1176 tty_update_time(&file_inode(file)->i_mtime);
1180 tty_write_unlock(tty);
1185 * tty_write_message - write a message to a certain tty, not just the console.
1186 * @tty: the destination tty_struct
1187 * @msg: the message to write
1189 * This is used for messages that need to be redirected to a specific tty.
1190 * We don't put it into the syslog queue right now maybe in the future if
1193 * We must still hold the BTM and test the CLOSING flag for the moment.
1196 void tty_write_message(struct tty_struct *tty, char *msg)
1199 mutex_lock(&tty->atomic_write_lock);
1201 if (tty->ops->write && tty->count > 0) {
1203 tty->ops->write(tty, msg, strlen(msg));
1206 tty_write_unlock(tty);
1213 * tty_write - write method for tty device file
1214 * @file: tty file pointer
1215 * @buf: user data to write
1216 * @count: bytes to write
1219 * Write data to a tty device via the line discipline.
1222 * Locks the line discipline as required
1223 * Writes to the tty driver are serialized by the atomic_write_lock
1224 * and are then processed in chunks to the device. The line discipline
1225 * write method will not be invoked in parallel for each device.
1228 static ssize_t tty_write(struct file *file, const char __user *buf,
1229 size_t count, loff_t *ppos)
1231 struct tty_struct *tty = file_tty(file);
1232 struct tty_ldisc *ld;
1235 if (tty_paranoia_check(tty, file_inode(file), "tty_write"))
1237 if (!tty || !tty->ops->write ||
1238 (test_bit(TTY_IO_ERROR, &tty->flags)))
1240 /* Short term debug to catch buggy drivers */
1241 if (tty->ops->write_room == NULL)
1242 printk(KERN_ERR "tty driver %s lacks a write_room method.\n",
1244 ld = tty_ldisc_ref_wait(tty);
1245 if (!ld->ops->write)
1248 ret = do_tty_write(ld->ops->write, tty, file, buf, count);
1249 tty_ldisc_deref(ld);
1253 ssize_t redirected_tty_write(struct file *file, const char __user *buf,
1254 size_t count, loff_t *ppos)
1256 struct file *p = NULL;
1258 spin_lock(&redirect_lock);
1260 p = get_file(redirect);
1261 spin_unlock(&redirect_lock);
1265 res = vfs_write(p, buf, count, &p->f_pos);
1269 return tty_write(file, buf, count, ppos);
1273 * tty_send_xchar - send priority character
1275 * Send a high priority character to the tty even if stopped
1277 * Locking: none for xchar method, write ordering for write method.
1280 int tty_send_xchar(struct tty_struct *tty, char ch)
1282 int was_stopped = tty->stopped;
1284 if (tty->ops->send_xchar) {
1285 tty->ops->send_xchar(tty, ch);
1289 if (tty_write_lock(tty, 0) < 0)
1290 return -ERESTARTSYS;
1294 tty->ops->write(tty, &ch, 1);
1297 tty_write_unlock(tty);
1301 static char ptychar[] = "pqrstuvwxyzabcde";
1304 * pty_line_name - generate name for a pty
1305 * @driver: the tty driver in use
1306 * @index: the minor number
1307 * @p: output buffer of at least 6 bytes
1309 * Generate a name from a driver reference and write it to the output
1314 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1316 int i = index + driver->name_base;
1317 /* ->name is initialized to "ttyp", but "tty" is expected */
1318 sprintf(p, "%s%c%x",
1319 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1320 ptychar[i >> 4 & 0xf], i & 0xf);
1324 * tty_line_name - generate name for a tty
1325 * @driver: the tty driver in use
1326 * @index: the minor number
1327 * @p: output buffer of at least 7 bytes
1329 * Generate a name from a driver reference and write it to the output
1334 static ssize_t tty_line_name(struct tty_driver *driver, int index, char *p)
1336 if (driver->flags & TTY_DRIVER_UNNUMBERED_NODE)
1337 return sprintf(p, "%s", driver->name);
1339 return sprintf(p, "%s%d", driver->name,
1340 index + driver->name_base);
1344 * tty_driver_lookup_tty() - find an existing tty, if any
1345 * @driver: the driver for the tty
1346 * @idx: the minor number
1348 * Return the tty, if found. If not found, return NULL or ERR_PTR() if the
1349 * driver lookup() method returns an error.
1351 * Locking: tty_mutex must be held. If the tty is found, bump the tty kref.
1353 static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
1354 struct inode *inode, int idx)
1356 struct tty_struct *tty;
1358 if (driver->ops->lookup)
1359 tty = driver->ops->lookup(driver, inode, idx);
1361 tty = driver->ttys[idx];
1369 * tty_init_termios - helper for termios setup
1370 * @tty: the tty to set up
1372 * Initialise the termios structures for this tty. Thus runs under
1373 * the tty_mutex currently so we can be relaxed about ordering.
1376 int tty_init_termios(struct tty_struct *tty)
1378 struct ktermios *tp;
1379 int idx = tty->index;
1381 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1382 tty->termios = tty->driver->init_termios;
1384 /* Check for lazy saved data */
1385 tp = tty->driver->termios[idx];
1389 tty->termios = tty->driver->init_termios;
1391 /* Compatibility until drivers always set this */
1392 tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
1393 tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
1396 EXPORT_SYMBOL_GPL(tty_init_termios);
1398 int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty)
1400 int ret = tty_init_termios(tty);
1404 tty_driver_kref_get(driver);
1406 driver->ttys[tty->index] = tty;
1409 EXPORT_SYMBOL_GPL(tty_standard_install);
1412 * tty_driver_install_tty() - install a tty entry in the driver
1413 * @driver: the driver for the tty
1416 * Install a tty object into the driver tables. The tty->index field
1417 * will be set by the time this is called. This method is responsible
1418 * for ensuring any need additional structures are allocated and
1421 * Locking: tty_mutex for now
1423 static int tty_driver_install_tty(struct tty_driver *driver,
1424 struct tty_struct *tty)
1426 return driver->ops->install ? driver->ops->install(driver, tty) :
1427 tty_standard_install(driver, tty);
1431 * tty_driver_remove_tty() - remove a tty from the driver tables
1432 * @driver: the driver for the tty
1433 * @idx: the minor number
1435 * Remvoe a tty object from the driver tables. The tty->index field
1436 * will be set by the time this is called.
1438 * Locking: tty_mutex for now
1440 void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *tty)
1442 if (driver->ops->remove)
1443 driver->ops->remove(driver, tty);
1445 driver->ttys[tty->index] = NULL;
1449 * tty_reopen() - fast re-open of an open tty
1450 * @tty - the tty to open
1452 * Return 0 on success, -errno on error.
1453 * Re-opens on master ptys are not allowed and return -EIO.
1455 * Locking: Caller must hold tty_lock
1457 static int tty_reopen(struct tty_struct *tty)
1459 struct tty_driver *driver = tty->driver;
1464 if (driver->type == TTY_DRIVER_TYPE_PTY &&
1465 driver->subtype == PTY_TYPE_MASTER)
1468 if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
1473 WARN_ON(!tty->ldisc);
1479 * tty_init_dev - initialise a tty device
1480 * @driver: tty driver we are opening a device on
1481 * @idx: device index
1482 * @ret_tty: returned tty structure
1484 * Prepare a tty device. This may not be a "new" clean device but
1485 * could also be an active device. The pty drivers require special
1486 * handling because of this.
1489 * The function is called under the tty_mutex, which
1490 * protects us from the tty struct or driver itself going away.
1492 * On exit the tty device has the line discipline attached and
1493 * a reference count of 1. If a pair was created for pty/tty use
1494 * and the other was a pty master then it too has a reference count of 1.
1496 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1497 * failed open. The new code protects the open with a mutex, so it's
1498 * really quite straightforward. The mutex locking can probably be
1499 * relaxed for the (most common) case of reopening a tty.
1502 struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
1504 struct tty_struct *tty;
1508 * First time open is complex, especially for PTY devices.
1509 * This code guarantees that either everything succeeds and the
1510 * TTY is ready for operation, or else the table slots are vacated
1511 * and the allocated memory released. (Except that the termios
1512 * and locked termios may be retained.)
1515 if (!try_module_get(driver->owner))
1516 return ERR_PTR(-ENODEV);
1518 tty = alloc_tty_struct(driver, idx);
1521 goto err_module_put;
1525 retval = tty_driver_install_tty(driver, tty);
1527 goto err_deinit_tty;
1530 tty->port = driver->ports[idx];
1532 WARN_RATELIMIT(!tty->port,
1533 "%s: %s driver does not set tty->port. This will crash the kernel later. Fix the driver!\n",
1534 __func__, tty->driver->name);
1536 tty->port->itty = tty;
1539 * Structures all installed ... call the ldisc open routines.
1540 * If we fail here just call release_tty to clean up. No need
1541 * to decrement the use counts, as release_tty doesn't care.
1543 retval = tty_ldisc_setup(tty, tty->link);
1545 goto err_release_tty;
1546 /* Return the tty locked so that it cannot vanish under the caller */
1551 deinitialize_tty_struct(tty);
1552 free_tty_struct(tty);
1554 module_put(driver->owner);
1555 return ERR_PTR(retval);
1557 /* call the tty release_tty routine to clean out this slot */
1560 printk_ratelimited(KERN_INFO "tty_init_dev: ldisc open failed, "
1561 "clearing slot %d\n", idx);
1562 release_tty(tty, idx);
1563 return ERR_PTR(retval);
1566 void tty_free_termios(struct tty_struct *tty)
1568 struct ktermios *tp;
1569 int idx = tty->index;
1571 /* If the port is going to reset then it has no termios to save */
1572 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1575 /* Stash the termios data */
1576 tp = tty->driver->termios[idx];
1578 tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
1580 pr_warn("tty: no memory to save termios state.\n");
1583 tty->driver->termios[idx] = tp;
1587 EXPORT_SYMBOL(tty_free_termios);
1590 * tty_flush_works - flush all works of a tty/pty pair
1591 * @tty: tty device to flush works for (or either end of a pty pair)
1593 * Sync flush all works belonging to @tty (and the 'other' tty).
1595 static void tty_flush_works(struct tty_struct *tty)
1597 flush_work(&tty->SAK_work);
1598 flush_work(&tty->hangup_work);
1600 flush_work(&tty->link->SAK_work);
1601 flush_work(&tty->link->hangup_work);
1606 * release_one_tty - release tty structure memory
1607 * @kref: kref of tty we are obliterating
1609 * Releases memory associated with a tty structure, and clears out the
1610 * driver table slots. This function is called when a device is no longer
1611 * in use. It also gets called when setup of a device fails.
1614 * takes the file list lock internally when working on the list
1615 * of ttys that the driver keeps.
1617 * This method gets called from a work queue so that the driver private
1618 * cleanup ops can sleep (needed for USB at least)
1620 static void release_one_tty(struct work_struct *work)
1622 struct tty_struct *tty =
1623 container_of(work, struct tty_struct, hangup_work);
1624 struct tty_driver *driver = tty->driver;
1625 struct module *owner = driver->owner;
1627 if (tty->ops->cleanup)
1628 tty->ops->cleanup(tty);
1631 tty_driver_kref_put(driver);
1634 spin_lock(&tty_files_lock);
1635 list_del_init(&tty->tty_files);
1636 spin_unlock(&tty_files_lock);
1639 put_pid(tty->session);
1640 free_tty_struct(tty);
1643 static void queue_release_one_tty(struct kref *kref)
1645 struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1647 /* The hangup queue is now free so we can reuse it rather than
1648 waste a chunk of memory for each port */
1649 INIT_WORK(&tty->hangup_work, release_one_tty);
1650 schedule_work(&tty->hangup_work);
1654 * tty_kref_put - release a tty kref
1657 * Release a reference to a tty device and if need be let the kref
1658 * layer destruct the object for us
1661 void tty_kref_put(struct tty_struct *tty)
1664 kref_put(&tty->kref, queue_release_one_tty);
1666 EXPORT_SYMBOL(tty_kref_put);
1669 * release_tty - release tty structure memory
1671 * Release both @tty and a possible linked partner (think pty pair),
1672 * and decrement the refcount of the backing module.
1676 * takes the file list lock internally when working on the list
1677 * of ttys that the driver keeps.
1680 static void release_tty(struct tty_struct *tty, int idx)
1682 /* This should always be true but check for the moment */
1683 WARN_ON(tty->index != idx);
1684 WARN_ON(!mutex_is_locked(&tty_mutex));
1685 if (tty->ops->shutdown)
1686 tty->ops->shutdown(tty);
1687 tty_free_termios(tty);
1688 tty_driver_remove_tty(tty->driver, tty);
1689 tty->port->itty = NULL;
1691 tty->link->port->itty = NULL;
1692 cancel_work_sync(&tty->port->buf.work);
1694 tty_kref_put(tty->link);
1699 * tty_release_checks - check a tty before real release
1700 * @tty: tty to check
1701 * @o_tty: link of @tty (if any)
1702 * @idx: index of the tty
1704 * Performs some paranoid checking before true release of the @tty.
1705 * This is a no-op unless TTY_PARANOIA_CHECK is defined.
1707 static int tty_release_checks(struct tty_struct *tty, int idx)
1709 #ifdef TTY_PARANOIA_CHECK
1710 if (idx < 0 || idx >= tty->driver->num) {
1711 tty_debug(tty, "bad idx %d\n", idx);
1715 /* not much to check for devpts */
1716 if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)
1719 if (tty != tty->driver->ttys[idx]) {
1720 tty_debug(tty, "bad driver table[%d] = %p\n",
1721 idx, tty->driver->ttys[idx]);
1724 if (tty->driver->other) {
1725 struct tty_struct *o_tty = tty->link;
1727 if (o_tty != tty->driver->other->ttys[idx]) {
1728 tty_debug(tty, "bad other table[%d] = %p\n",
1729 idx, tty->driver->other->ttys[idx]);
1732 if (o_tty->link != tty) {
1733 tty_debug(tty, "bad link = %p\n", o_tty->link);
1742 * tty_release - vfs callback for close
1743 * @inode: inode of tty
1744 * @filp: file pointer for handle to tty
1746 * Called the last time each file handle is closed that references
1747 * this tty. There may however be several such references.
1750 * Takes bkl. See tty_release_dev
1752 * Even releasing the tty structures is a tricky business.. We have
1753 * to be very careful that the structures are all released at the
1754 * same time, as interrupts might otherwise get the wrong pointers.
1756 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1757 * lead to double frees or releasing memory still in use.
1760 int tty_release(struct inode *inode, struct file *filp)
1762 struct tty_struct *tty = file_tty(filp);
1763 struct tty_struct *o_tty = NULL;
1764 int do_sleep, final;
1769 if (tty_paranoia_check(tty, inode, __func__))
1773 check_tty_count(tty, __func__);
1775 __tty_fasync(-1, filp, 0);
1778 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1779 tty->driver->subtype == PTY_TYPE_MASTER)
1782 if (tty_release_checks(tty, idx)) {
1787 tty_debug_hangup(tty, "(tty count=%d)...\n", tty->count);
1789 if (tty->ops->close)
1790 tty->ops->close(tty, filp);
1792 /* If tty is pty master, lock the slave pty (stable lock order) */
1793 tty_lock_slave(o_tty);
1796 * Sanity check: if tty->count is going to zero, there shouldn't be
1797 * any waiters on tty->read_wait or tty->write_wait. We test the
1798 * wait queues and kick everyone out _before_ actually starting to
1799 * close. This ensures that we won't block while releasing the tty
1802 * The test for the o_tty closing is necessary, since the master and
1803 * slave sides may close in any order. If the slave side closes out
1804 * first, its count will be one, since the master side holds an open.
1805 * Thus this test wouldn't be triggered at the time the slave closed,
1811 if (tty->count <= 1) {
1812 if (waitqueue_active(&tty->read_wait)) {
1813 wake_up_poll(&tty->read_wait, POLLIN);
1816 if (waitqueue_active(&tty->write_wait)) {
1817 wake_up_poll(&tty->write_wait, POLLOUT);
1821 if (o_tty && o_tty->count <= 1) {
1822 if (waitqueue_active(&o_tty->read_wait)) {
1823 wake_up_poll(&o_tty->read_wait, POLLIN);
1826 if (waitqueue_active(&o_tty->write_wait)) {
1827 wake_up_poll(&o_tty->write_wait, POLLOUT);
1836 printk(KERN_WARNING "%s: %s: read/write wait queue active!\n",
1837 __func__, tty_name(tty));
1839 schedule_timeout_killable(timeout);
1840 if (timeout < 120 * HZ)
1841 timeout = 2 * timeout + 1;
1843 timeout = MAX_SCHEDULE_TIMEOUT;
1847 if (--o_tty->count < 0) {
1848 printk(KERN_WARNING "%s: bad pty slave count (%d) for %s\n",
1849 __func__, o_tty->count, tty_name(o_tty));
1853 if (--tty->count < 0) {
1854 printk(KERN_WARNING "%s: bad tty->count (%d) for %s\n",
1855 __func__, tty->count, tty_name(tty));
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);
2069 /* safe to drop the kref from tty_driver_lookup_tty() */
2071 retval = tty_reopen(tty);
2074 tty = ERR_PTR(retval);
2076 } else { /* Returns with the tty_lock held for now */
2077 tty = tty_init_dev(driver, index);
2078 mutex_unlock(&tty_mutex);
2081 tty_driver_kref_put(driver);
2085 retval = PTR_ERR(tty);
2089 tty_add_file(tty, filp);
2091 check_tty_count(tty, __func__);
2092 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2093 tty->driver->subtype == PTY_TYPE_MASTER)
2096 tty_debug_hangup(tty, "(tty count=%d)\n", tty->count);
2099 retval = tty->ops->open(tty, filp);
2102 filp->f_flags = saved_flags;
2105 tty_debug_hangup(tty, "error %d, releasing...\n", retval);
2107 tty_unlock(tty); /* need to call tty_release without BTM */
2108 tty_release(inode, filp);
2109 if (retval != -ERESTARTSYS)
2112 if (signal_pending(current))
2117 * Need to reset f_op in case a hangup happened.
2119 if (tty_hung_up_p(filp))
2120 filp->f_op = &tty_fops;
2123 clear_bit(TTY_HUPPED, &tty->flags);
2126 read_lock(&tasklist_lock);
2127 spin_lock_irq(¤t->sighand->siglock);
2129 current->signal->leader &&
2130 !current->signal->tty &&
2131 tty->session == NULL)
2132 __proc_set_tty(tty);
2133 spin_unlock_irq(¤t->sighand->siglock);
2134 read_unlock(&tasklist_lock);
2138 mutex_unlock(&tty_mutex);
2139 /* after locks to avoid deadlock */
2140 if (!IS_ERR_OR_NULL(driver))
2141 tty_driver_kref_put(driver);
2143 tty_free_file(filp);
2150 * tty_poll - check tty status
2151 * @filp: file being polled
2152 * @wait: poll wait structures to update
2154 * Call the line discipline polling method to obtain the poll
2155 * status of the device.
2157 * Locking: locks called line discipline but ldisc poll method
2158 * may be re-entered freely by other callers.
2161 static unsigned int tty_poll(struct file *filp, poll_table *wait)
2163 struct tty_struct *tty = file_tty(filp);
2164 struct tty_ldisc *ld;
2167 if (tty_paranoia_check(tty, file_inode(filp), "tty_poll"))
2170 ld = tty_ldisc_ref_wait(tty);
2172 ret = ld->ops->poll(tty, filp, wait);
2173 tty_ldisc_deref(ld);
2177 static int __tty_fasync(int fd, struct file *filp, int on)
2179 struct tty_struct *tty = file_tty(filp);
2180 struct tty_ldisc *ldisc;
2181 unsigned long flags;
2184 if (tty_paranoia_check(tty, file_inode(filp), "tty_fasync"))
2187 retval = fasync_helper(fd, filp, on, &tty->fasync);
2191 ldisc = tty_ldisc_ref(tty);
2193 if (ldisc->ops->fasync)
2194 ldisc->ops->fasync(tty, on);
2195 tty_ldisc_deref(ldisc);
2202 spin_lock_irqsave(&tty->ctrl_lock, flags);
2205 type = PIDTYPE_PGID;
2207 pid = task_pid(current);
2211 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2212 __f_setown(filp, pid, type, 0);
2220 static int tty_fasync(int fd, struct file *filp, int on)
2222 struct tty_struct *tty = file_tty(filp);
2226 retval = __tty_fasync(fd, filp, on);
2233 * tiocsti - fake input character
2234 * @tty: tty to fake input into
2235 * @p: pointer to character
2237 * Fake input to a tty device. Does the necessary locking and
2240 * FIXME: does not honour flow control ??
2243 * Called functions take tty_ldiscs_lock
2244 * current->signal->tty check is safe without locks
2246 * FIXME: may race normal receive processing
2249 static int tiocsti(struct tty_struct *tty, char __user *p)
2252 struct tty_ldisc *ld;
2254 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2256 if (get_user(ch, p))
2258 tty_audit_tiocsti(tty, ch);
2259 ld = tty_ldisc_ref_wait(tty);
2260 ld->ops->receive_buf(tty, &ch, &mbz, 1);
2261 tty_ldisc_deref(ld);
2266 * tiocgwinsz - implement window query ioctl
2268 * @arg: user buffer for result
2270 * Copies the kernel idea of the window size into the user buffer.
2272 * Locking: tty->winsize_mutex is taken to ensure the winsize data
2276 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2280 mutex_lock(&tty->winsize_mutex);
2281 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2282 mutex_unlock(&tty->winsize_mutex);
2284 return err ? -EFAULT: 0;
2288 * tty_do_resize - resize event
2289 * @tty: tty being resized
2290 * @rows: rows (character)
2291 * @cols: cols (character)
2293 * Update the termios variables and send the necessary signals to
2294 * peform a terminal resize correctly
2297 int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
2302 mutex_lock(&tty->winsize_mutex);
2303 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
2306 /* Signal the foreground process group */
2307 pgrp = tty_get_pgrp(tty);
2309 kill_pgrp(pgrp, SIGWINCH, 1);
2314 mutex_unlock(&tty->winsize_mutex);
2317 EXPORT_SYMBOL(tty_do_resize);
2320 * tiocswinsz - implement window size set ioctl
2321 * @tty; tty side of tty
2322 * @arg: user buffer for result
2324 * Copies the user idea of the window size to the kernel. Traditionally
2325 * this is just advisory information but for the Linux console it
2326 * actually has driver level meaning and triggers a VC resize.
2329 * Driver dependent. The default do_resize method takes the
2330 * tty termios mutex and ctrl_lock. The console takes its own lock
2331 * then calls into the default method.
2334 static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
2336 struct winsize tmp_ws;
2337 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2340 if (tty->ops->resize)
2341 return tty->ops->resize(tty, &tmp_ws);
2343 return tty_do_resize(tty, &tmp_ws);
2347 * tioccons - allow admin to move logical console
2348 * @file: the file to become console
2350 * Allow the administrator to move the redirected console device
2352 * Locking: uses redirect_lock to guard the redirect information
2355 static int tioccons(struct file *file)
2357 if (!capable(CAP_SYS_ADMIN))
2359 if (file->f_op->write == redirected_tty_write) {
2361 spin_lock(&redirect_lock);
2364 spin_unlock(&redirect_lock);
2369 spin_lock(&redirect_lock);
2371 spin_unlock(&redirect_lock);
2374 redirect = get_file(file);
2375 spin_unlock(&redirect_lock);
2380 * fionbio - non blocking ioctl
2381 * @file: file to set blocking value
2382 * @p: user parameter
2384 * Historical tty interfaces had a blocking control ioctl before
2385 * the generic functionality existed. This piece of history is preserved
2386 * in the expected tty API of posix OS's.
2388 * Locking: none, the open file handle ensures it won't go away.
2391 static int fionbio(struct file *file, int __user *p)
2395 if (get_user(nonblock, p))
2398 spin_lock(&file->f_lock);
2400 file->f_flags |= O_NONBLOCK;
2402 file->f_flags &= ~O_NONBLOCK;
2403 spin_unlock(&file->f_lock);
2408 * tiocsctty - set controlling tty
2409 * @tty: tty structure
2410 * @arg: user argument
2412 * This ioctl is used to manage job control. It permits a session
2413 * leader to set this tty as the controlling tty for the session.
2416 * Takes tty_lock() to serialize proc_set_tty() for this tty
2417 * Takes tasklist_lock internally to walk sessions
2418 * Takes ->siglock() when updating signal->tty
2421 static int tiocsctty(struct tty_struct *tty, int arg)
2426 read_lock(&tasklist_lock);
2428 if (current->signal->leader && (task_session(current) == tty->session))
2432 * The process must be a session leader and
2433 * not have a controlling tty already.
2435 if (!current->signal->leader || current->signal->tty) {
2442 * This tty is already the controlling
2443 * tty for another session group!
2445 if (arg == 1 && capable(CAP_SYS_ADMIN)) {
2449 session_clear_tty(tty->session);
2457 read_unlock(&tasklist_lock);
2463 * tty_get_pgrp - return a ref counted pgrp pid
2466 * Returns a refcounted instance of the pid struct for the process
2467 * group controlling the tty.
2470 struct pid *tty_get_pgrp(struct tty_struct *tty)
2472 unsigned long flags;
2475 spin_lock_irqsave(&tty->ctrl_lock, flags);
2476 pgrp = get_pid(tty->pgrp);
2477 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2481 EXPORT_SYMBOL_GPL(tty_get_pgrp);
2484 * This checks not only the pgrp, but falls back on the pid if no
2485 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
2488 * The caller must hold rcu lock or the tasklist lock.
2490 static struct pid *session_of_pgrp(struct pid *pgrp)
2492 struct task_struct *p;
2493 struct pid *sid = NULL;
2495 p = pid_task(pgrp, PIDTYPE_PGID);
2497 p = pid_task(pgrp, PIDTYPE_PID);
2499 sid = task_session(p);
2505 * tiocgpgrp - get process group
2506 * @tty: tty passed by user
2507 * @real_tty: tty side of the tty passed by the user if a pty else the tty
2510 * Obtain the process group of the tty. If there is no process group
2513 * Locking: none. Reference to current->signal->tty is safe.
2516 static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2521 * (tty == real_tty) is a cheap way of
2522 * testing if the tty is NOT a master pty.
2524 if (tty == real_tty && current->signal->tty != real_tty)
2526 pid = tty_get_pgrp(real_tty);
2527 ret = put_user(pid_vnr(pid), p);
2533 * tiocspgrp - attempt to set process group
2534 * @tty: tty passed by user
2535 * @real_tty: tty side device matching tty passed by user
2538 * Set the process group of the tty to the session passed. Only
2539 * permitted where the tty session is our session.
2541 * Locking: RCU, ctrl lock
2544 static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2548 int retval = tty_check_change(real_tty);
2549 unsigned long flags;
2555 if (!current->signal->tty ||
2556 (current->signal->tty != real_tty) ||
2557 (real_tty->session != task_session(current)))
2559 if (get_user(pgrp_nr, p))
2564 pgrp = find_vpid(pgrp_nr);
2569 if (session_of_pgrp(pgrp) != task_session(current))
2572 spin_lock_irqsave(&tty->ctrl_lock, flags);
2573 put_pid(real_tty->pgrp);
2574 real_tty->pgrp = get_pid(pgrp);
2575 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2582 * tiocgsid - get session id
2583 * @tty: tty passed by user
2584 * @real_tty: tty side of the tty passed by the user if a pty else the tty
2585 * @p: pointer to returned session id
2587 * Obtain the session id of the tty. If there is no session
2590 * Locking: none. Reference to current->signal->tty is safe.
2593 static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2596 * (tty == real_tty) is a cheap way of
2597 * testing if the tty is NOT a master pty.
2599 if (tty == real_tty && current->signal->tty != real_tty)
2601 if (!real_tty->session)
2603 return put_user(pid_vnr(real_tty->session), p);
2607 * tiocsetd - set line discipline
2609 * @p: pointer to user data
2611 * Set the line discipline according to user request.
2613 * Locking: see tty_set_ldisc, this function is just a helper
2616 static int tiocsetd(struct tty_struct *tty, int __user *p)
2621 if (get_user(ldisc, p))
2624 ret = tty_set_ldisc(tty, ldisc);
2630 * send_break - performed time break
2631 * @tty: device to break on
2632 * @duration: timeout in mS
2634 * Perform a timed break on hardware that lacks its own driver level
2635 * timed break functionality.
2638 * atomic_write_lock serializes
2642 static int send_break(struct tty_struct *tty, unsigned int duration)
2646 if (tty->ops->break_ctl == NULL)
2649 if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2650 retval = tty->ops->break_ctl(tty, duration);
2652 /* Do the work ourselves */
2653 if (tty_write_lock(tty, 0) < 0)
2655 retval = tty->ops->break_ctl(tty, -1);
2658 if (!signal_pending(current))
2659 msleep_interruptible(duration);
2660 retval = tty->ops->break_ctl(tty, 0);
2662 tty_write_unlock(tty);
2663 if (signal_pending(current))
2670 * tty_tiocmget - get modem status
2672 * @file: user file pointer
2673 * @p: pointer to result
2675 * Obtain the modem status bits from the tty driver if the feature
2676 * is supported. Return -EINVAL if it is not available.
2678 * Locking: none (up to the driver)
2681 static int tty_tiocmget(struct tty_struct *tty, int __user *p)
2683 int retval = -EINVAL;
2685 if (tty->ops->tiocmget) {
2686 retval = tty->ops->tiocmget(tty);
2689 retval = put_user(retval, p);
2695 * tty_tiocmset - set modem status
2697 * @cmd: command - clear bits, set bits or set all
2698 * @p: pointer to desired bits
2700 * Set the modem status bits from the tty driver if the feature
2701 * is supported. Return -EINVAL if it is not available.
2703 * Locking: none (up to the driver)
2706 static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
2710 unsigned int set, clear, val;
2712 if (tty->ops->tiocmset == NULL)
2715 retval = get_user(val, p);
2731 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2732 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2733 return tty->ops->tiocmset(tty, set, clear);
2736 static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
2738 int retval = -EINVAL;
2739 struct serial_icounter_struct icount;
2740 memset(&icount, 0, sizeof(icount));
2741 if (tty->ops->get_icount)
2742 retval = tty->ops->get_icount(tty, &icount);
2745 if (copy_to_user(arg, &icount, sizeof(icount)))
2750 static void tty_warn_deprecated_flags(struct serial_struct __user *ss)
2752 static DEFINE_RATELIMIT_STATE(depr_flags,
2753 DEFAULT_RATELIMIT_INTERVAL,
2754 DEFAULT_RATELIMIT_BURST);
2755 char comm[TASK_COMM_LEN];
2758 if (get_user(flags, &ss->flags))
2761 flags &= ASYNC_DEPRECATED;
2763 if (flags && __ratelimit(&depr_flags))
2764 pr_warning("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
2765 __func__, get_task_comm(comm, current), flags);
2769 * if pty, return the slave side (real_tty)
2770 * otherwise, return self
2772 static struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
2774 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2775 tty->driver->subtype == PTY_TYPE_MASTER)
2781 * Split this up, as gcc can choke on it otherwise..
2783 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2785 struct tty_struct *tty = file_tty(file);
2786 struct tty_struct *real_tty;
2787 void __user *p = (void __user *)arg;
2789 struct tty_ldisc *ld;
2791 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2794 real_tty = tty_pair_get_tty(tty);
2797 * Factor out some common prep work
2805 retval = tty_check_change(tty);
2808 if (cmd != TIOCCBRK) {
2809 tty_wait_until_sent(tty, 0);
2810 if (signal_pending(current))
2821 return tiocsti(tty, p);
2823 return tiocgwinsz(real_tty, p);
2825 return tiocswinsz(real_tty, p);
2827 return real_tty != tty ? -EINVAL : tioccons(file);
2829 return fionbio(file, p);
2831 set_bit(TTY_EXCLUSIVE, &tty->flags);
2834 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2838 int excl = test_bit(TTY_EXCLUSIVE, &tty->flags);
2839 return put_user(excl, (int __user *)p);
2842 if (current->signal->tty != tty)
2847 return tiocsctty(tty, arg);
2849 return tiocgpgrp(tty, real_tty, p);
2851 return tiocspgrp(tty, real_tty, p);
2853 return tiocgsid(tty, real_tty, p);
2855 return put_user(tty->ldisc->ops->num, (int __user *)p);
2857 return tiocsetd(tty, p);
2859 if (!capable(CAP_SYS_ADMIN))
2865 unsigned int ret = new_encode_dev(tty_devnum(real_tty));
2866 return put_user(ret, (unsigned int __user *)p);
2871 case TIOCSBRK: /* Turn break on, unconditionally */
2872 if (tty->ops->break_ctl)
2873 return tty->ops->break_ctl(tty, -1);
2875 case TIOCCBRK: /* Turn break off, unconditionally */
2876 if (tty->ops->break_ctl)
2877 return tty->ops->break_ctl(tty, 0);
2879 case TCSBRK: /* SVID version: non-zero arg --> no break */
2880 /* non-zero arg means wait for all output data
2881 * to be sent (performed above) but don't send break.
2882 * This is used by the tcdrain() termios function.
2885 return send_break(tty, 250);
2887 case TCSBRKP: /* support for POSIX tcsendbreak() */
2888 return send_break(tty, arg ? arg*100 : 250);
2891 return tty_tiocmget(tty, p);
2895 return tty_tiocmset(tty, cmd, p);
2897 retval = tty_tiocgicount(tty, p);
2898 /* For the moment allow fall through to the old method */
2899 if (retval != -EINVAL)
2906 /* flush tty buffer and allow ldisc to process ioctl */
2907 tty_buffer_flush(tty, NULL);
2912 tty_warn_deprecated_flags(p);
2915 if (tty->ops->ioctl) {
2916 retval = tty->ops->ioctl(tty, cmd, arg);
2917 if (retval != -ENOIOCTLCMD)
2920 ld = tty_ldisc_ref_wait(tty);
2922 if (ld->ops->ioctl) {
2923 retval = ld->ops->ioctl(tty, file, cmd, arg);
2924 if (retval == -ENOIOCTLCMD)
2927 tty_ldisc_deref(ld);
2931 #ifdef CONFIG_COMPAT
2932 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2935 struct tty_struct *tty = file_tty(file);
2936 struct tty_ldisc *ld;
2937 int retval = -ENOIOCTLCMD;
2939 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2942 if (tty->ops->compat_ioctl) {
2943 retval = tty->ops->compat_ioctl(tty, cmd, arg);
2944 if (retval != -ENOIOCTLCMD)
2948 ld = tty_ldisc_ref_wait(tty);
2949 if (ld->ops->compat_ioctl)
2950 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
2952 retval = n_tty_compat_ioctl_helper(tty, file, cmd, arg);
2953 tty_ldisc_deref(ld);
2959 static int this_tty(const void *t, struct file *file, unsigned fd)
2961 if (likely(file->f_op->read != tty_read))
2963 return file_tty(file) != t ? 0 : fd + 1;
2967 * This implements the "Secure Attention Key" --- the idea is to
2968 * prevent trojan horses by killing all processes associated with this
2969 * tty when the user hits the "Secure Attention Key". Required for
2970 * super-paranoid applications --- see the Orange Book for more details.
2972 * This code could be nicer; ideally it should send a HUP, wait a few
2973 * seconds, then send a INT, and then a KILL signal. But you then
2974 * have to coordinate with the init process, since all processes associated
2975 * with the current tty must be dead before the new getty is allowed
2978 * Now, if it would be correct ;-/ The current code has a nasty hole -
2979 * it doesn't catch files in flight. We may send the descriptor to ourselves
2980 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
2982 * Nasty bug: do_SAK is being called in interrupt context. This can
2983 * deadlock. We punt it up to process context. AKPM - 16Mar2001
2985 void __do_SAK(struct tty_struct *tty)
2990 struct task_struct *g, *p;
2991 struct pid *session;
2996 session = tty->session;
2998 tty_ldisc_flush(tty);
3000 tty_driver_flush_buffer(tty);
3002 read_lock(&tasklist_lock);
3003 /* Kill the entire session */
3004 do_each_pid_task(session, PIDTYPE_SID, p) {
3005 printk(KERN_NOTICE "SAK: killed process %d"
3006 " (%s): task_session(p)==tty->session\n",
3007 task_pid_nr(p), p->comm);
3008 send_sig(SIGKILL, p, 1);
3009 } while_each_pid_task(session, PIDTYPE_SID, p);
3010 /* Now kill any processes that happen to have the
3013 do_each_thread(g, p) {
3014 if (p->signal->tty == tty) {
3015 printk(KERN_NOTICE "SAK: killed process %d"
3016 " (%s): task_session(p)==tty->session\n",
3017 task_pid_nr(p), p->comm);
3018 send_sig(SIGKILL, p, 1);
3022 i = iterate_fd(p->files, 0, this_tty, tty);
3024 printk(KERN_NOTICE "SAK: killed process %d"
3025 " (%s): fd#%d opened to the tty\n",
3026 task_pid_nr(p), p->comm, i - 1);
3027 force_sig(SIGKILL, p);
3030 } while_each_thread(g, p);
3031 read_unlock(&tasklist_lock);
3035 static void do_SAK_work(struct work_struct *work)
3037 struct tty_struct *tty =
3038 container_of(work, struct tty_struct, SAK_work);
3043 * The tq handling here is a little racy - tty->SAK_work may already be queued.
3044 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
3045 * the values which we write to it will be identical to the values which it
3046 * already has. --akpm
3048 void do_SAK(struct tty_struct *tty)
3052 schedule_work(&tty->SAK_work);
3055 EXPORT_SYMBOL(do_SAK);
3057 static int dev_match_devt(struct device *dev, const void *data)
3059 const dev_t *devt = data;
3060 return dev->devt == *devt;
3063 /* Must put_device() after it's unused! */
3064 static struct device *tty_get_device(struct tty_struct *tty)
3066 dev_t devt = tty_devnum(tty);
3067 return class_find_device(tty_class, NULL, &devt, dev_match_devt);
3074 * This subroutine allocates and initializes a tty structure.
3076 * Locking: none - tty in question is not exposed at this point
3079 struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
3081 struct tty_struct *tty;
3083 tty = kzalloc(sizeof(*tty), GFP_KERNEL);
3087 kref_init(&tty->kref);
3088 tty->magic = TTY_MAGIC;
3089 tty_ldisc_init(tty);
3090 tty->session = NULL;
3092 mutex_init(&tty->legacy_mutex);
3093 mutex_init(&tty->throttle_mutex);
3094 init_rwsem(&tty->termios_rwsem);
3095 mutex_init(&tty->winsize_mutex);
3096 init_ldsem(&tty->ldisc_sem);
3097 init_waitqueue_head(&tty->write_wait);
3098 init_waitqueue_head(&tty->read_wait);
3099 INIT_WORK(&tty->hangup_work, do_tty_hangup);
3100 mutex_init(&tty->atomic_write_lock);
3101 spin_lock_init(&tty->ctrl_lock);
3102 spin_lock_init(&tty->flow_lock);
3103 INIT_LIST_HEAD(&tty->tty_files);
3104 INIT_WORK(&tty->SAK_work, do_SAK_work);
3106 tty->driver = driver;
3107 tty->ops = driver->ops;
3109 tty_line_name(driver, idx, tty->name);
3110 tty->dev = tty_get_device(tty);
3116 * deinitialize_tty_struct
3117 * @tty: tty to deinitialize
3119 * This subroutine deinitializes a tty structure that has been newly
3120 * allocated but tty_release cannot be called on that yet.
3122 * Locking: none - tty in question must not be exposed at this point
3124 void deinitialize_tty_struct(struct tty_struct *tty)
3126 tty_ldisc_deinit(tty);
3130 * tty_put_char - write one character to a tty
3134 * Write one byte to the tty using the provided put_char method
3135 * if present. Returns the number of characters successfully output.
3137 * Note: the specific put_char operation in the driver layer may go
3138 * away soon. Don't call it directly, use this method
3141 int tty_put_char(struct tty_struct *tty, unsigned char ch)
3143 if (tty->ops->put_char)
3144 return tty->ops->put_char(tty, ch);
3145 return tty->ops->write(tty, &ch, 1);
3147 EXPORT_SYMBOL_GPL(tty_put_char);
3149 struct class *tty_class;
3151 static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
3152 unsigned int index, unsigned int count)
3154 /* init here, since reused cdevs cause crashes */
3155 driver->cdevs[index] = cdev_alloc();
3156 if (!driver->cdevs[index])
3158 cdev_init(driver->cdevs[index], &tty_fops);
3159 driver->cdevs[index]->owner = driver->owner;
3160 return cdev_add(driver->cdevs[index], dev, count);
3164 * tty_register_device - register a tty device
3165 * @driver: the tty driver that describes the tty device
3166 * @index: the index in the tty driver for this tty device
3167 * @device: a struct device that is associated with this tty device.
3168 * This field is optional, if there is no known struct device
3169 * for this tty device it can be set to NULL safely.
3171 * Returns a pointer to the struct device for this tty device
3172 * (or ERR_PTR(-EFOO) on error).
3174 * This call is required to be made to register an individual tty device
3175 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3176 * that bit is not set, this function should not be called by a tty
3182 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
3183 struct device *device)
3185 return tty_register_device_attr(driver, index, device, NULL, NULL);
3187 EXPORT_SYMBOL(tty_register_device);
3189 static void tty_device_create_release(struct device *dev)
3191 pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
3196 * tty_register_device_attr - register a tty device
3197 * @driver: the tty driver that describes the tty device
3198 * @index: the index in the tty driver for this tty device
3199 * @device: a struct device that is associated with this tty device.
3200 * This field is optional, if there is no known struct device
3201 * for this tty device it can be set to NULL safely.
3202 * @drvdata: Driver data to be set to device.
3203 * @attr_grp: Attribute group to be set on device.
3205 * Returns a pointer to the struct device for this tty device
3206 * (or ERR_PTR(-EFOO) on error).
3208 * This call is required to be made to register an individual tty device
3209 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3210 * that bit is not set, this function should not be called by a tty
3215 struct device *tty_register_device_attr(struct tty_driver *driver,
3216 unsigned index, struct device *device,
3218 const struct attribute_group **attr_grp)
3221 dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
3222 struct device *dev = NULL;
3223 int retval = -ENODEV;
3226 if (index >= driver->num) {
3227 printk(KERN_ERR "Attempt to register invalid tty line number "
3229 return ERR_PTR(-EINVAL);
3232 if (driver->type == TTY_DRIVER_TYPE_PTY)
3233 pty_line_name(driver, index, name);
3235 tty_line_name(driver, index, name);
3237 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3238 retval = tty_cdev_add(driver, devt, index, 1);
3244 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
3251 dev->class = tty_class;
3252 dev->parent = device;
3253 dev->release = tty_device_create_release;
3254 dev_set_name(dev, "%s", name);
3255 dev->groups = attr_grp;
3256 dev_set_drvdata(dev, drvdata);
3258 retval = device_register(dev);
3267 cdev_del(driver->cdevs[index]);
3268 driver->cdevs[index] = NULL;
3270 return ERR_PTR(retval);
3272 EXPORT_SYMBOL_GPL(tty_register_device_attr);
3275 * tty_unregister_device - unregister a tty device
3276 * @driver: the tty driver that describes the tty device
3277 * @index: the index in the tty driver for this tty device
3279 * If a tty device is registered with a call to tty_register_device() then
3280 * this function must be called when the tty device is gone.
3285 void tty_unregister_device(struct tty_driver *driver, unsigned index)
3287 device_destroy(tty_class,
3288 MKDEV(driver->major, driver->minor_start) + index);
3289 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3290 cdev_del(driver->cdevs[index]);
3291 driver->cdevs[index] = NULL;
3294 EXPORT_SYMBOL(tty_unregister_device);
3297 * __tty_alloc_driver -- allocate tty driver
3298 * @lines: count of lines this driver can handle at most
3299 * @owner: module which is repsonsible for this driver
3300 * @flags: some of TTY_DRIVER_* flags, will be set in driver->flags
3302 * This should not be called directly, some of the provided macros should be
3303 * used instead. Use IS_ERR and friends on @retval.
3305 struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
3306 unsigned long flags)
3308 struct tty_driver *driver;
3309 unsigned int cdevs = 1;
3312 if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
3313 return ERR_PTR(-EINVAL);
3315 driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
3317 return ERR_PTR(-ENOMEM);
3319 kref_init(&driver->kref);
3320 driver->magic = TTY_DRIVER_MAGIC;
3321 driver->num = lines;
3322 driver->owner = owner;
3323 driver->flags = flags;
3325 if (!(flags & TTY_DRIVER_DEVPTS_MEM)) {
3326 driver->ttys = kcalloc(lines, sizeof(*driver->ttys),
3328 driver->termios = kcalloc(lines, sizeof(*driver->termios),
3330 if (!driver->ttys || !driver->termios) {
3336 if (!(flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3337 driver->ports = kcalloc(lines, sizeof(*driver->ports),
3339 if (!driver->ports) {
3346 driver->cdevs = kcalloc(cdevs, sizeof(*driver->cdevs), GFP_KERNEL);
3347 if (!driver->cdevs) {
3354 kfree(driver->ports);
3355 kfree(driver->ttys);
3356 kfree(driver->termios);
3357 kfree(driver->cdevs);
3359 return ERR_PTR(err);
3361 EXPORT_SYMBOL(__tty_alloc_driver);
3363 static void destruct_tty_driver(struct kref *kref)
3365 struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
3367 struct ktermios *tp;
3369 if (driver->flags & TTY_DRIVER_INSTALLED) {
3371 * Free the termios and termios_locked structures because
3372 * we don't want to get memory leaks when modular tty
3373 * drivers are removed from the kernel.
3375 for (i = 0; i < driver->num; i++) {
3376 tp = driver->termios[i];
3378 driver->termios[i] = NULL;
3381 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3382 tty_unregister_device(driver, i);
3384 proc_tty_unregister_driver(driver);
3385 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
3386 cdev_del(driver->cdevs[0]);
3388 kfree(driver->cdevs);
3389 kfree(driver->ports);
3390 kfree(driver->termios);
3391 kfree(driver->ttys);
3395 void tty_driver_kref_put(struct tty_driver *driver)
3397 kref_put(&driver->kref, destruct_tty_driver);
3399 EXPORT_SYMBOL(tty_driver_kref_put);
3401 void tty_set_operations(struct tty_driver *driver,
3402 const struct tty_operations *op)
3406 EXPORT_SYMBOL(tty_set_operations);
3408 void put_tty_driver(struct tty_driver *d)
3410 tty_driver_kref_put(d);
3412 EXPORT_SYMBOL(put_tty_driver);
3415 * Called by a tty driver to register itself.
3417 int tty_register_driver(struct tty_driver *driver)
3424 if (!driver->major) {
3425 error = alloc_chrdev_region(&dev, driver->minor_start,
3426 driver->num, driver->name);
3428 driver->major = MAJOR(dev);
3429 driver->minor_start = MINOR(dev);
3432 dev = MKDEV(driver->major, driver->minor_start);
3433 error = register_chrdev_region(dev, driver->num, driver->name);
3438 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) {
3439 error = tty_cdev_add(driver, dev, 0, driver->num);
3441 goto err_unreg_char;
3444 mutex_lock(&tty_mutex);
3445 list_add(&driver->tty_drivers, &tty_drivers);
3446 mutex_unlock(&tty_mutex);
3448 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
3449 for (i = 0; i < driver->num; i++) {
3450 d = tty_register_device(driver, i, NULL);
3453 goto err_unreg_devs;
3457 proc_tty_register_driver(driver);
3458 driver->flags |= TTY_DRIVER_INSTALLED;
3462 for (i--; i >= 0; i--)
3463 tty_unregister_device(driver, i);
3465 mutex_lock(&tty_mutex);
3466 list_del(&driver->tty_drivers);
3467 mutex_unlock(&tty_mutex);
3470 unregister_chrdev_region(dev, driver->num);
3474 EXPORT_SYMBOL(tty_register_driver);
3477 * Called by a tty driver to unregister itself.
3479 int tty_unregister_driver(struct tty_driver *driver)
3483 if (driver->refcount)
3486 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3488 mutex_lock(&tty_mutex);
3489 list_del(&driver->tty_drivers);
3490 mutex_unlock(&tty_mutex);
3494 EXPORT_SYMBOL(tty_unregister_driver);
3496 dev_t tty_devnum(struct tty_struct *tty)
3498 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3500 EXPORT_SYMBOL(tty_devnum);
3502 void tty_default_fops(struct file_operations *fops)
3508 * Initialize the console device. This is called *early*, so
3509 * we can't necessarily depend on lots of kernel help here.
3510 * Just do some early initializations, and do the complex setup
3513 void __init console_init(void)
3517 /* Setup the default TTY line discipline. */
3521 * set up the console device so that later boot sequences can
3522 * inform about problems etc..
3524 call = __con_initcall_start;
3525 while (call < __con_initcall_end) {
3531 static char *tty_devnode(struct device *dev, umode_t *mode)
3535 if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
3536 dev->devt == MKDEV(TTYAUX_MAJOR, 2))
3541 static int __init tty_class_init(void)
3543 tty_class = class_create(THIS_MODULE, "tty");
3544 if (IS_ERR(tty_class))
3545 return PTR_ERR(tty_class);
3546 tty_class->devnode = tty_devnode;
3550 postcore_initcall(tty_class_init);
3552 /* 3/2004 jmc: why do these devices exist? */
3553 static struct cdev tty_cdev, console_cdev;
3555 static ssize_t show_cons_active(struct device *dev,
3556 struct device_attribute *attr, char *buf)
3558 struct console *cs[16];
3564 for_each_console(c) {
3569 if ((c->flags & CON_ENABLED) == 0)
3572 if (i >= ARRAY_SIZE(cs))
3576 int index = cs[i]->index;
3577 struct tty_driver *drv = cs[i]->device(cs[i], &index);
3579 /* don't resolve tty0 as some programs depend on it */
3580 if (drv && (cs[i]->index > 0 || drv->major != TTY_MAJOR))
3581 count += tty_line_name(drv, index, buf + count);
3583 count += sprintf(buf + count, "%s%d",
3584 cs[i]->name, cs[i]->index);
3586 count += sprintf(buf + count, "%c", i ? ' ':'\n');
3592 static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
3594 static struct attribute *cons_dev_attrs[] = {
3595 &dev_attr_active.attr,
3599 ATTRIBUTE_GROUPS(cons_dev);
3601 static struct device *consdev;
3603 void console_sysfs_notify(void)
3606 sysfs_notify(&consdev->kobj, NULL, "active");
3610 * Ok, now we can initialize the rest of the tty devices and can count
3611 * on memory allocations, interrupts etc..
3613 int __init tty_init(void)
3615 cdev_init(&tty_cdev, &tty_fops);
3616 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3617 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3618 panic("Couldn't register /dev/tty driver\n");
3619 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
3621 cdev_init(&console_cdev, &console_fops);
3622 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3623 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3624 panic("Couldn't register /dev/console driver\n");
3625 consdev = device_create_with_groups(tty_class, NULL,
3626 MKDEV(TTYAUX_MAJOR, 1), NULL,
3627 cons_dev_groups, "console");
3628 if (IS_ERR(consdev))
3632 vty_init(&console_fops);