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
110 #define TTY_PARANOIA_CHECK 1
111 #define CHECK_TTY_COUNT 1
113 struct ktermios tty_std_termios = { /* for the benefit of tty drivers */
114 .c_iflag = ICRNL | IXON,
115 .c_oflag = OPOST | ONLCR,
116 .c_cflag = B38400 | CS8 | CREAD | HUPCL,
117 .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
118 ECHOCTL | ECHOKE | IEXTEN,
124 EXPORT_SYMBOL(tty_std_termios);
126 /* This list gets poked at by procfs and various bits of boot up code. This
127 could do with some rationalisation such as pulling the tty proc function
130 LIST_HEAD(tty_drivers); /* linked list of tty drivers */
132 /* Mutex to protect creating and releasing a tty. This is shared with
133 vt.c for deeply disgusting hack reasons */
134 DEFINE_MUTEX(tty_mutex);
135 EXPORT_SYMBOL(tty_mutex);
137 /* Spinlock to protect the tty->tty_files list */
138 DEFINE_SPINLOCK(tty_files_lock);
140 static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
141 static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
142 ssize_t redirected_tty_write(struct file *, const char __user *,
144 static unsigned int tty_poll(struct file *, poll_table *);
145 static int tty_open(struct inode *, struct file *);
146 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
148 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
151 #define tty_compat_ioctl NULL
153 static int __tty_fasync(int fd, struct file *filp, int on);
154 static int tty_fasync(int fd, struct file *filp, int on);
155 static void release_tty(struct tty_struct *tty, int idx);
156 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
157 static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
160 * free_tty_struct - free a disused tty
161 * @tty: tty struct to free
163 * Free the write buffers, tty queue and tty memory itself.
165 * Locking: none. Must be called after tty is definitely unused
168 void free_tty_struct(struct tty_struct *tty)
173 put_device(tty->dev);
174 kfree(tty->write_buf);
175 tty->magic = 0xDEADDEAD;
179 static inline struct tty_struct *file_tty(struct file *file)
181 return ((struct tty_file_private *)file->private_data)->tty;
184 int tty_alloc_file(struct file *file)
186 struct tty_file_private *priv;
188 priv = kmalloc(sizeof(*priv), GFP_KERNEL);
192 file->private_data = priv;
197 /* Associate a new file with the tty structure */
198 void tty_add_file(struct tty_struct *tty, struct file *file)
200 struct tty_file_private *priv = file->private_data;
205 spin_lock(&tty_files_lock);
206 list_add(&priv->list, &tty->tty_files);
207 spin_unlock(&tty_files_lock);
211 * tty_free_file - free file->private_data
213 * This shall be used only for fail path handling when tty_add_file was not
216 void tty_free_file(struct file *file)
218 struct tty_file_private *priv = file->private_data;
220 file->private_data = NULL;
224 /* Delete file from its tty */
225 static void tty_del_file(struct file *file)
227 struct tty_file_private *priv = file->private_data;
229 spin_lock(&tty_files_lock);
230 list_del(&priv->list);
231 spin_unlock(&tty_files_lock);
236 #define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base)
239 * tty_name - return tty naming
240 * @tty: tty structure
241 * @buf: buffer for output
243 * Convert a tty structure into a name. The name reflects the kernel
244 * naming policy and if udev is in use may not reflect user space
249 char *tty_name(struct tty_struct *tty, char *buf)
251 if (!tty) /* Hmm. NULL pointer. That's fun. */
252 strcpy(buf, "NULL tty");
254 strcpy(buf, tty->name);
258 EXPORT_SYMBOL(tty_name);
260 int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
263 #ifdef TTY_PARANOIA_CHECK
266 "null TTY for (%d:%d) in %s\n",
267 imajor(inode), iminor(inode), routine);
270 if (tty->magic != TTY_MAGIC) {
272 "bad magic number for tty struct (%d:%d) in %s\n",
273 imajor(inode), iminor(inode), routine);
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)
398 if (current->signal->tty != tty)
401 spin_lock_irqsave(&tty->ctrl_lock, flags);
404 printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");
407 if (task_pgrp(current) == tty->pgrp)
409 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
410 if (is_ignored(SIGTTOU))
412 if (is_current_pgrp_orphaned()) {
416 kill_pgrp(task_pgrp(current), SIGTTOU, 1);
417 set_thread_flag(TIF_SIGPENDING);
422 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
426 EXPORT_SYMBOL(tty_check_change);
428 static ssize_t hung_up_tty_read(struct file *file, char __user *buf,
429 size_t count, loff_t *ppos)
434 static ssize_t hung_up_tty_write(struct file *file, const char __user *buf,
435 size_t count, loff_t *ppos)
440 /* No kernel lock held - none needed ;) */
441 static unsigned int hung_up_tty_poll(struct file *filp, poll_table *wait)
443 return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM;
446 static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
449 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
452 static long hung_up_tty_compat_ioctl(struct file *file,
453 unsigned int cmd, unsigned long arg)
455 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
458 static const struct file_operations tty_fops = {
463 .unlocked_ioctl = tty_ioctl,
464 .compat_ioctl = tty_compat_ioctl,
466 .release = tty_release,
467 .fasync = tty_fasync,
470 static const struct file_operations console_fops = {
473 .write = redirected_tty_write,
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 hung_up_tty_fops = {
484 .read = hung_up_tty_read,
485 .write = hung_up_tty_write,
486 .poll = hung_up_tty_poll,
487 .unlocked_ioctl = hung_up_tty_ioctl,
488 .compat_ioctl = hung_up_tty_compat_ioctl,
489 .release = tty_release,
492 static DEFINE_SPINLOCK(redirect_lock);
493 static struct file *redirect;
496 * tty_wakeup - request more data
499 * Internal and external helper for wakeups of tty. This function
500 * informs the line discipline if present that the driver is ready
501 * to receive more output data.
504 void tty_wakeup(struct tty_struct *tty)
506 struct tty_ldisc *ld;
508 if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
509 ld = tty_ldisc_ref(tty);
511 if (ld->ops->write_wakeup)
512 ld->ops->write_wakeup(tty);
516 wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
519 EXPORT_SYMBOL_GPL(tty_wakeup);
522 * tty_signal_session_leader - sends SIGHUP to session leader
523 * @tty controlling tty
524 * @exit_session if non-zero, signal all foreground group processes
526 * Send SIGHUP and SIGCONT to the session leader and its process group.
527 * Optionally, signal all processes in the foreground process group.
529 * Returns the number of processes in the session with this tty
530 * as their controlling terminal. This value is used to drop
531 * tty references for those processes.
533 static int tty_signal_session_leader(struct tty_struct *tty, int exit_session)
535 struct task_struct *p;
537 struct pid *tty_pgrp = NULL;
539 read_lock(&tasklist_lock);
541 do_each_pid_task(tty->session, PIDTYPE_SID, p) {
542 spin_lock_irq(&p->sighand->siglock);
543 if (p->signal->tty == tty) {
544 p->signal->tty = NULL;
545 /* We defer the dereferences outside fo
549 if (!p->signal->leader) {
550 spin_unlock_irq(&p->sighand->siglock);
553 __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
554 __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
555 put_pid(p->signal->tty_old_pgrp); /* A noop */
556 spin_lock(&tty->ctrl_lock);
557 tty_pgrp = get_pid(tty->pgrp);
559 p->signal->tty_old_pgrp = get_pid(tty->pgrp);
560 spin_unlock(&tty->ctrl_lock);
561 spin_unlock_irq(&p->sighand->siglock);
562 } while_each_pid_task(tty->session, PIDTYPE_SID, p);
564 read_unlock(&tasklist_lock);
568 kill_pgrp(tty_pgrp, SIGHUP, exit_session);
576 * __tty_hangup - actual handler for hangup events
579 * This can be called by a "kworker" kernel thread. That is process
580 * synchronous but doesn't hold any locks, so we need to make sure we
581 * have the appropriate locks for what we're doing.
583 * The hangup event clears any pending redirections onto the hung up
584 * device. It ensures future writes will error and it does the needed
585 * line discipline hangup and signal delivery. The tty object itself
590 * redirect lock for undoing redirection
591 * file list lock for manipulating list of ttys
592 * tty_ldiscs_lock from called functions
593 * termios_rwsem resetting termios data
594 * tasklist_lock to walk task list for hangup event
595 * ->siglock to protect ->signal/->sighand
597 static void __tty_hangup(struct tty_struct *tty, int exit_session)
599 struct file *cons_filp = NULL;
600 struct file *filp, *f = NULL;
601 struct tty_file_private *priv;
602 int closecount = 0, n;
609 spin_lock(&redirect_lock);
610 if (redirect && file_tty(redirect) == tty) {
614 spin_unlock(&redirect_lock);
618 if (test_bit(TTY_HUPPED, &tty->flags)) {
623 /* some functions below drop BTM, so we need this bit */
624 set_bit(TTY_HUPPING, &tty->flags);
626 /* inuse_filps is protected by the single tty lock,
627 this really needs to change if we want to flush the
628 workqueue with the lock held */
629 check_tty_count(tty, "tty_hangup");
631 spin_lock(&tty_files_lock);
632 /* This breaks for file handles being sent over AF_UNIX sockets ? */
633 list_for_each_entry(priv, &tty->tty_files, list) {
635 if (filp->f_op->write == redirected_tty_write)
637 if (filp->f_op->write != tty_write)
640 __tty_fasync(-1, filp, 0); /* can't block */
641 filp->f_op = &hung_up_tty_fops;
643 spin_unlock(&tty_files_lock);
645 refs = tty_signal_session_leader(tty, exit_session);
646 /* Account for the p->signal references we killed */
651 * it drops BTM and thus races with reopen
652 * we protect the race by TTY_HUPPING
654 tty_ldisc_hangup(tty);
656 spin_lock_irq(&tty->ctrl_lock);
657 clear_bit(TTY_THROTTLED, &tty->flags);
658 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
659 put_pid(tty->session);
663 tty->ctrl_status = 0;
664 spin_unlock_irq(&tty->ctrl_lock);
667 * If one of the devices matches a console pointer, we
668 * cannot just call hangup() because that will cause
669 * tty->count and state->count to go out of sync.
670 * So we just call close() the right number of times.
674 for (n = 0; n < closecount; n++)
675 tty->ops->close(tty, cons_filp);
676 } else if (tty->ops->hangup)
677 tty->ops->hangup(tty);
679 * We don't want to have driver/ldisc interactions beyond
680 * the ones we did here. The driver layer expects no
681 * calls after ->hangup() from the ldisc side. However we
682 * can't yet guarantee all that.
684 set_bit(TTY_HUPPED, &tty->flags);
685 clear_bit(TTY_HUPPING, &tty->flags);
693 static void do_tty_hangup(struct work_struct *work)
695 struct tty_struct *tty =
696 container_of(work, struct tty_struct, hangup_work);
698 __tty_hangup(tty, 0);
702 * tty_hangup - trigger a hangup event
703 * @tty: tty to hangup
705 * A carrier loss (virtual or otherwise) has occurred on this like
706 * schedule a hangup sequence to run after this event.
709 void tty_hangup(struct tty_struct *tty)
711 #ifdef TTY_DEBUG_HANGUP
713 printk(KERN_DEBUG "%s hangup...\n", tty_name(tty, buf));
715 schedule_work(&tty->hangup_work);
718 EXPORT_SYMBOL(tty_hangup);
721 * tty_vhangup - process vhangup
722 * @tty: tty to hangup
724 * The user has asked via system call for the terminal to be hung up.
725 * We do this synchronously so that when the syscall returns the process
726 * is complete. That guarantee is necessary for security reasons.
729 void tty_vhangup(struct tty_struct *tty)
731 #ifdef TTY_DEBUG_HANGUP
734 printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf));
736 __tty_hangup(tty, 0);
739 EXPORT_SYMBOL(tty_vhangup);
743 * tty_vhangup_self - process vhangup for own ctty
745 * Perform a vhangup on the current controlling tty
748 void tty_vhangup_self(void)
750 struct tty_struct *tty;
752 tty = get_current_tty();
760 * tty_vhangup_session - hangup session leader exit
761 * @tty: tty to hangup
763 * The session leader is exiting and hanging up its controlling terminal.
764 * Every process in the foreground process group is signalled SIGHUP.
766 * We do this synchronously so that when the syscall returns the process
767 * is complete. That guarantee is necessary for security reasons.
770 static void tty_vhangup_session(struct tty_struct *tty)
772 #ifdef TTY_DEBUG_HANGUP
775 printk(KERN_DEBUG "%s vhangup session...\n", tty_name(tty, buf));
777 __tty_hangup(tty, 1);
781 * tty_hung_up_p - was tty hung up
782 * @filp: file pointer of tty
784 * Return true if the tty has been subject to a vhangup or a carrier
788 int tty_hung_up_p(struct file *filp)
790 return (filp->f_op == &hung_up_tty_fops);
793 EXPORT_SYMBOL(tty_hung_up_p);
795 static void session_clear_tty(struct pid *session)
797 struct task_struct *p;
798 do_each_pid_task(session, PIDTYPE_SID, p) {
800 } while_each_pid_task(session, PIDTYPE_SID, p);
804 * disassociate_ctty - disconnect controlling tty
805 * @on_exit: true if exiting so need to "hang up" the session
807 * This function is typically called only by the session leader, when
808 * it wants to disassociate itself from its controlling tty.
810 * It performs the following functions:
811 * (1) Sends a SIGHUP and SIGCONT to the foreground process group
812 * (2) Clears the tty from being controlling the session
813 * (3) Clears the controlling tty for all processes in the
816 * The argument on_exit is set to 1 if called when a process is
817 * exiting; it is 0 if called by the ioctl TIOCNOTTY.
820 * BTM is taken for hysterical raisins, and held when
821 * called from no_tty().
822 * tty_mutex is taken to protect tty
823 * ->siglock is taken to protect ->signal/->sighand
824 * tasklist_lock is taken to walk process list for sessions
825 * ->siglock is taken to protect ->signal/->sighand
828 void disassociate_ctty(int on_exit)
830 struct tty_struct *tty;
832 if (!current->signal->leader)
835 tty = get_current_tty();
837 if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY) {
838 tty_vhangup_session(tty);
840 struct pid *tty_pgrp = tty_get_pgrp(tty);
842 kill_pgrp(tty_pgrp, SIGHUP, on_exit);
844 kill_pgrp(tty_pgrp, SIGCONT, on_exit);
850 } else if (on_exit) {
851 struct pid *old_pgrp;
852 spin_lock_irq(¤t->sighand->siglock);
853 old_pgrp = current->signal->tty_old_pgrp;
854 current->signal->tty_old_pgrp = NULL;
855 spin_unlock_irq(¤t->sighand->siglock);
857 kill_pgrp(old_pgrp, SIGHUP, on_exit);
858 kill_pgrp(old_pgrp, SIGCONT, on_exit);
864 spin_lock_irq(¤t->sighand->siglock);
865 put_pid(current->signal->tty_old_pgrp);
866 current->signal->tty_old_pgrp = NULL;
868 tty = tty_kref_get(current->signal->tty);
871 spin_lock_irqsave(&tty->ctrl_lock, flags);
872 put_pid(tty->session);
876 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
879 #ifdef TTY_DEBUG_HANGUP
880 printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
885 spin_unlock_irq(¤t->sighand->siglock);
886 /* Now clear signal->tty under the lock */
887 read_lock(&tasklist_lock);
888 session_clear_tty(task_session(current));
889 read_unlock(&tasklist_lock);
894 * no_tty - Ensure the current process does not have a controlling tty
898 /* FIXME: Review locking here. The tty_lock never covered any race
899 between a new association and proc_clear_tty but possible we need
900 to protect against this anyway */
901 struct task_struct *tsk = current;
902 disassociate_ctty(0);
908 * stop_tty - propagate flow control
911 * Perform flow control to the driver. May be called
912 * on an already stopped device and will not re-call the driver
915 * This functionality is used by both the line disciplines for
916 * halting incoming flow and by the driver. It may therefore be
917 * called from any context, may be under the tty atomic_write_lock
924 void __stop_tty(struct tty_struct *tty)
930 (tty->ops->stop)(tty);
933 void stop_tty(struct tty_struct *tty)
937 spin_lock_irqsave(&tty->flow_lock, flags);
939 spin_unlock_irqrestore(&tty->flow_lock, flags);
941 EXPORT_SYMBOL(stop_tty);
944 * start_tty - propagate flow control
947 * Start a tty that has been stopped if at all possible. If this
948 * tty was previous stopped and is now being started, the driver
949 * start method is invoked and the line discipline woken.
955 void __start_tty(struct tty_struct *tty)
957 if (!tty->stopped || tty->flow_stopped)
961 (tty->ops->start)(tty);
965 void start_tty(struct tty_struct *tty)
969 spin_lock_irqsave(&tty->flow_lock, flags);
971 spin_unlock_irqrestore(&tty->flow_lock, flags);
973 EXPORT_SYMBOL(start_tty);
975 /* We limit tty time update visibility to every 8 seconds or so. */
976 static void tty_update_time(struct timespec *time)
978 unsigned long sec = get_seconds() & ~7;
979 if ((long)(sec - time->tv_sec) > 0)
984 * tty_read - read method for tty device files
985 * @file: pointer to tty file
987 * @count: size of user buffer
990 * Perform the read system call function on this terminal device. Checks
991 * for hung up devices before calling the line discipline method.
994 * Locks the line discipline internally while needed. Multiple
995 * read calls may be outstanding in parallel.
998 static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
1002 struct inode *inode = file_inode(file);
1003 struct tty_struct *tty = file_tty(file);
1004 struct tty_ldisc *ld;
1006 if (tty_paranoia_check(tty, inode, "tty_read"))
1008 if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags)))
1011 /* We want to wait for the line discipline to sort out in this
1013 ld = tty_ldisc_ref_wait(tty);
1015 i = (ld->ops->read)(tty, file, buf, count);
1018 tty_ldisc_deref(ld);
1021 tty_update_time(&inode->i_atime);
1026 static void tty_write_unlock(struct tty_struct *tty)
1028 mutex_unlock(&tty->atomic_write_lock);
1029 wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
1032 static int tty_write_lock(struct tty_struct *tty, int ndelay)
1034 if (!mutex_trylock(&tty->atomic_write_lock)) {
1037 if (mutex_lock_interruptible(&tty->atomic_write_lock))
1038 return -ERESTARTSYS;
1044 * Split writes up in sane blocksizes to avoid
1045 * denial-of-service type attacks
1047 static inline ssize_t do_tty_write(
1048 ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
1049 struct tty_struct *tty,
1051 const char __user *buf,
1054 ssize_t ret, written = 0;
1057 ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
1062 * We chunk up writes into a temporary buffer. This
1063 * simplifies low-level drivers immensely, since they
1064 * don't have locking issues and user mode accesses.
1066 * But if TTY_NO_WRITE_SPLIT is set, we should use a
1069 * The default chunk-size is 2kB, because the NTTY
1070 * layer has problems with bigger chunks. It will
1071 * claim to be able to handle more characters than
1074 * FIXME: This can probably go away now except that 64K chunks
1075 * are too likely to fail unless switched to vmalloc...
1078 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
1083 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
1084 if (tty->write_cnt < chunk) {
1085 unsigned char *buf_chunk;
1090 buf_chunk = kmalloc(chunk, GFP_KERNEL);
1095 kfree(tty->write_buf);
1096 tty->write_cnt = chunk;
1097 tty->write_buf = buf_chunk;
1100 /* Do the write .. */
1102 size_t size = count;
1106 if (copy_from_user(tty->write_buf, buf, size))
1108 ret = write(tty, file, tty->write_buf, size);
1117 if (signal_pending(current))
1122 tty_update_time(&file_inode(file)->i_mtime);
1126 tty_write_unlock(tty);
1131 * tty_write_message - write a message to a certain tty, not just the console.
1132 * @tty: the destination tty_struct
1133 * @msg: the message to write
1135 * This is used for messages that need to be redirected to a specific tty.
1136 * We don't put it into the syslog queue right now maybe in the future if
1139 * We must still hold the BTM and test the CLOSING flag for the moment.
1142 void tty_write_message(struct tty_struct *tty, char *msg)
1145 mutex_lock(&tty->atomic_write_lock);
1147 if (tty->ops->write && !test_bit(TTY_CLOSING, &tty->flags)) {
1149 tty->ops->write(tty, msg, strlen(msg));
1152 tty_write_unlock(tty);
1159 * tty_write - write method for tty device file
1160 * @file: tty file pointer
1161 * @buf: user data to write
1162 * @count: bytes to write
1165 * Write data to a tty device via the line discipline.
1168 * Locks the line discipline as required
1169 * Writes to the tty driver are serialized by the atomic_write_lock
1170 * and are then processed in chunks to the device. The line discipline
1171 * write method will not be invoked in parallel for each device.
1174 static ssize_t tty_write(struct file *file, const char __user *buf,
1175 size_t count, loff_t *ppos)
1177 struct tty_struct *tty = file_tty(file);
1178 struct tty_ldisc *ld;
1181 if (tty_paranoia_check(tty, file_inode(file), "tty_write"))
1183 if (!tty || !tty->ops->write ||
1184 (test_bit(TTY_IO_ERROR, &tty->flags)))
1186 /* Short term debug to catch buggy drivers */
1187 if (tty->ops->write_room == NULL)
1188 printk(KERN_ERR "tty driver %s lacks a write_room method.\n",
1190 ld = tty_ldisc_ref_wait(tty);
1191 if (!ld->ops->write)
1194 ret = do_tty_write(ld->ops->write, tty, file, buf, count);
1195 tty_ldisc_deref(ld);
1199 ssize_t redirected_tty_write(struct file *file, const char __user *buf,
1200 size_t count, loff_t *ppos)
1202 struct file *p = NULL;
1204 spin_lock(&redirect_lock);
1206 p = get_file(redirect);
1207 spin_unlock(&redirect_lock);
1211 res = vfs_write(p, buf, count, &p->f_pos);
1215 return tty_write(file, buf, count, ppos);
1219 * tty_send_xchar - send priority character
1221 * Send a high priority character to the tty even if stopped
1223 * Locking: none for xchar method, write ordering for write method.
1226 int tty_send_xchar(struct tty_struct *tty, char ch)
1228 int was_stopped = tty->stopped;
1230 if (tty->ops->send_xchar) {
1231 tty->ops->send_xchar(tty, ch);
1235 if (tty_write_lock(tty, 0) < 0)
1236 return -ERESTARTSYS;
1240 tty->ops->write(tty, &ch, 1);
1243 tty_write_unlock(tty);
1247 static char ptychar[] = "pqrstuvwxyzabcde";
1250 * pty_line_name - generate name for a pty
1251 * @driver: the tty driver in use
1252 * @index: the minor number
1253 * @p: output buffer of at least 6 bytes
1255 * Generate a name from a driver reference and write it to the output
1260 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1262 int i = index + driver->name_base;
1263 /* ->name is initialized to "ttyp", but "tty" is expected */
1264 sprintf(p, "%s%c%x",
1265 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1266 ptychar[i >> 4 & 0xf], i & 0xf);
1270 * tty_line_name - generate name for a tty
1271 * @driver: the tty driver in use
1272 * @index: the minor number
1273 * @p: output buffer of at least 7 bytes
1275 * Generate a name from a driver reference and write it to the output
1280 static ssize_t tty_line_name(struct tty_driver *driver, int index, char *p)
1282 if (driver->flags & TTY_DRIVER_UNNUMBERED_NODE)
1283 return sprintf(p, "%s", driver->name);
1285 return sprintf(p, "%s%d", driver->name,
1286 index + driver->name_base);
1290 * tty_driver_lookup_tty() - find an existing tty, if any
1291 * @driver: the driver for the tty
1292 * @idx: the minor number
1294 * Return the tty, if found or ERR_PTR() otherwise.
1296 * Locking: tty_mutex must be held. If tty is found, the mutex must
1297 * be held until the 'fast-open' is also done. Will change once we
1298 * have refcounting in the driver and per driver locking
1300 static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
1301 struct inode *inode, int idx)
1303 if (driver->ops->lookup)
1304 return driver->ops->lookup(driver, inode, idx);
1306 return driver->ttys[idx];
1310 * tty_init_termios - helper for termios setup
1311 * @tty: the tty to set up
1313 * Initialise the termios structures for this tty. Thus runs under
1314 * the tty_mutex currently so we can be relaxed about ordering.
1317 int tty_init_termios(struct tty_struct *tty)
1319 struct ktermios *tp;
1320 int idx = tty->index;
1322 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1323 tty->termios = tty->driver->init_termios;
1325 /* Check for lazy saved data */
1326 tp = tty->driver->termios[idx];
1330 tty->termios = tty->driver->init_termios;
1332 /* Compatibility until drivers always set this */
1333 tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
1334 tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
1337 EXPORT_SYMBOL_GPL(tty_init_termios);
1339 int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty)
1341 int ret = tty_init_termios(tty);
1345 tty_driver_kref_get(driver);
1347 driver->ttys[tty->index] = tty;
1350 EXPORT_SYMBOL_GPL(tty_standard_install);
1353 * tty_driver_install_tty() - install a tty entry in the driver
1354 * @driver: the driver for the tty
1357 * Install a tty object into the driver tables. The tty->index field
1358 * will be set by the time this is called. This method is responsible
1359 * for ensuring any need additional structures are allocated and
1362 * Locking: tty_mutex for now
1364 static int tty_driver_install_tty(struct tty_driver *driver,
1365 struct tty_struct *tty)
1367 return driver->ops->install ? driver->ops->install(driver, tty) :
1368 tty_standard_install(driver, tty);
1372 * tty_driver_remove_tty() - remove a tty from the driver tables
1373 * @driver: the driver for the tty
1374 * @idx: the minor number
1376 * Remvoe a tty object from the driver tables. The tty->index field
1377 * will be set by the time this is called.
1379 * Locking: tty_mutex for now
1381 void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *tty)
1383 if (driver->ops->remove)
1384 driver->ops->remove(driver, tty);
1386 driver->ttys[tty->index] = NULL;
1390 * tty_reopen() - fast re-open of an open tty
1391 * @tty - the tty to open
1393 * Return 0 on success, -errno on error.
1395 * Locking: tty_mutex must be held from the time the tty was found
1396 * till this open completes.
1398 static int tty_reopen(struct tty_struct *tty)
1400 struct tty_driver *driver = tty->driver;
1402 if (test_bit(TTY_CLOSING, &tty->flags) ||
1403 test_bit(TTY_HUPPING, &tty->flags))
1406 if (driver->type == TTY_DRIVER_TYPE_PTY &&
1407 driver->subtype == PTY_TYPE_MASTER) {
1409 * special case for PTY masters: only one open permitted,
1410 * and the slave side open count is incremented as well.
1419 WARN_ON(!tty->ldisc);
1425 * tty_init_dev - initialise a tty device
1426 * @driver: tty driver we are opening a device on
1427 * @idx: device index
1428 * @ret_tty: returned tty structure
1430 * Prepare a tty device. This may not be a "new" clean device but
1431 * could also be an active device. The pty drivers require special
1432 * handling because of this.
1435 * The function is called under the tty_mutex, which
1436 * protects us from the tty struct or driver itself going away.
1438 * On exit the tty device has the line discipline attached and
1439 * a reference count of 1. If a pair was created for pty/tty use
1440 * and the other was a pty master then it too has a reference count of 1.
1442 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1443 * failed open. The new code protects the open with a mutex, so it's
1444 * really quite straightforward. The mutex locking can probably be
1445 * relaxed for the (most common) case of reopening a tty.
1448 struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
1450 struct tty_struct *tty;
1454 * First time open is complex, especially for PTY devices.
1455 * This code guarantees that either everything succeeds and the
1456 * TTY is ready for operation, or else the table slots are vacated
1457 * and the allocated memory released. (Except that the termios
1458 * and locked termios may be retained.)
1461 if (!try_module_get(driver->owner))
1462 return ERR_PTR(-ENODEV);
1464 tty = alloc_tty_struct(driver, idx);
1467 goto err_module_put;
1471 retval = tty_driver_install_tty(driver, tty);
1473 goto err_deinit_tty;
1476 tty->port = driver->ports[idx];
1478 WARN_RATELIMIT(!tty->port,
1479 "%s: %s driver does not set tty->port. This will crash the kernel later. Fix the driver!\n",
1480 __func__, tty->driver->name);
1482 tty->port->itty = tty;
1485 * Structures all installed ... call the ldisc open routines.
1486 * If we fail here just call release_tty to clean up. No need
1487 * to decrement the use counts, as release_tty doesn't care.
1489 retval = tty_ldisc_setup(tty, tty->link);
1491 goto err_release_tty;
1492 /* Return the tty locked so that it cannot vanish under the caller */
1497 deinitialize_tty_struct(tty);
1498 free_tty_struct(tty);
1500 module_put(driver->owner);
1501 return ERR_PTR(retval);
1503 /* call the tty release_tty routine to clean out this slot */
1506 printk_ratelimited(KERN_INFO "tty_init_dev: ldisc open failed, "
1507 "clearing slot %d\n", idx);
1508 release_tty(tty, idx);
1509 return ERR_PTR(retval);
1512 void tty_free_termios(struct tty_struct *tty)
1514 struct ktermios *tp;
1515 int idx = tty->index;
1517 /* If the port is going to reset then it has no termios to save */
1518 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1521 /* Stash the termios data */
1522 tp = tty->driver->termios[idx];
1524 tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
1526 pr_warn("tty: no memory to save termios state.\n");
1529 tty->driver->termios[idx] = tp;
1533 EXPORT_SYMBOL(tty_free_termios);
1536 * tty_flush_works - flush all works of a tty
1537 * @tty: tty device to flush works for
1539 * Sync flush all works belonging to @tty.
1541 static void tty_flush_works(struct tty_struct *tty)
1543 flush_work(&tty->SAK_work);
1544 flush_work(&tty->hangup_work);
1548 * release_one_tty - release tty structure memory
1549 * @kref: kref of tty we are obliterating
1551 * Releases memory associated with a tty structure, and clears out the
1552 * driver table slots. This function is called when a device is no longer
1553 * in use. It also gets called when setup of a device fails.
1556 * takes the file list lock internally when working on the list
1557 * of ttys that the driver keeps.
1559 * This method gets called from a work queue so that the driver private
1560 * cleanup ops can sleep (needed for USB at least)
1562 static void release_one_tty(struct work_struct *work)
1564 struct tty_struct *tty =
1565 container_of(work, struct tty_struct, hangup_work);
1566 struct tty_driver *driver = tty->driver;
1567 struct module *owner = driver->owner;
1569 if (tty->ops->cleanup)
1570 tty->ops->cleanup(tty);
1573 tty_driver_kref_put(driver);
1576 spin_lock(&tty_files_lock);
1577 list_del_init(&tty->tty_files);
1578 spin_unlock(&tty_files_lock);
1581 put_pid(tty->session);
1582 free_tty_struct(tty);
1585 static void queue_release_one_tty(struct kref *kref)
1587 struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1589 /* The hangup queue is now free so we can reuse it rather than
1590 waste a chunk of memory for each port */
1591 INIT_WORK(&tty->hangup_work, release_one_tty);
1592 schedule_work(&tty->hangup_work);
1596 * tty_kref_put - release a tty kref
1599 * Release a reference to a tty device and if need be let the kref
1600 * layer destruct the object for us
1603 void tty_kref_put(struct tty_struct *tty)
1606 kref_put(&tty->kref, queue_release_one_tty);
1608 EXPORT_SYMBOL(tty_kref_put);
1611 * release_tty - release tty structure memory
1613 * Release both @tty and a possible linked partner (think pty pair),
1614 * and decrement the refcount of the backing module.
1618 * takes the file list lock internally when working on the list
1619 * of ttys that the driver keeps.
1622 static void release_tty(struct tty_struct *tty, int idx)
1624 /* This should always be true but check for the moment */
1625 WARN_ON(tty->index != idx);
1626 WARN_ON(!mutex_is_locked(&tty_mutex));
1627 if (tty->ops->shutdown)
1628 tty->ops->shutdown(tty);
1629 tty_free_termios(tty);
1630 tty_driver_remove_tty(tty->driver, tty);
1631 tty->port->itty = NULL;
1633 tty->link->port->itty = NULL;
1634 cancel_work_sync(&tty->port->buf.work);
1637 tty_kref_put(tty->link);
1642 * tty_release_checks - check a tty before real release
1643 * @tty: tty to check
1644 * @o_tty: link of @tty (if any)
1645 * @idx: index of the tty
1647 * Performs some paranoid checking before true release of the @tty.
1648 * This is a no-op unless TTY_PARANOIA_CHECK is defined.
1650 static int tty_release_checks(struct tty_struct *tty, struct tty_struct *o_tty,
1653 #ifdef TTY_PARANOIA_CHECK
1654 if (idx < 0 || idx >= tty->driver->num) {
1655 printk(KERN_DEBUG "%s: bad idx when trying to free (%s)\n",
1656 __func__, tty->name);
1660 /* not much to check for devpts */
1661 if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)
1664 if (tty != tty->driver->ttys[idx]) {
1665 printk(KERN_DEBUG "%s: driver.table[%d] not tty for (%s)\n",
1666 __func__, idx, tty->name);
1669 if (tty->driver->other) {
1670 if (o_tty != tty->driver->other->ttys[idx]) {
1671 printk(KERN_DEBUG "%s: other->table[%d] not o_tty for (%s)\n",
1672 __func__, idx, tty->name);
1675 if (o_tty->link != tty) {
1676 printk(KERN_DEBUG "%s: bad pty pointers\n", __func__);
1685 * tty_release - vfs callback for close
1686 * @inode: inode of tty
1687 * @filp: file pointer for handle to tty
1689 * Called the last time each file handle is closed that references
1690 * this tty. There may however be several such references.
1693 * Takes bkl. See tty_release_dev
1695 * Even releasing the tty structures is a tricky business.. We have
1696 * to be very careful that the structures are all released at the
1697 * same time, as interrupts might otherwise get the wrong pointers.
1699 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1700 * lead to double frees or releasing memory still in use.
1703 int tty_release(struct inode *inode, struct file *filp)
1705 struct tty_struct *tty = file_tty(filp);
1706 struct tty_struct *o_tty;
1707 int pty_master, tty_closing, o_tty_closing, do_sleep;
1711 if (tty_paranoia_check(tty, inode, __func__))
1715 check_tty_count(tty, __func__);
1717 __tty_fasync(-1, filp, 0);
1720 pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1721 tty->driver->subtype == PTY_TYPE_MASTER);
1722 /* Review: parallel close */
1725 if (tty_release_checks(tty, o_tty, idx)) {
1730 #ifdef TTY_DEBUG_HANGUP
1731 printk(KERN_DEBUG "%s: %s (tty count=%d)...\n", __func__,
1732 tty_name(tty, buf), tty->count);
1735 if (tty->ops->close)
1736 tty->ops->close(tty, filp);
1740 * Sanity check: if tty->count is going to zero, there shouldn't be
1741 * any waiters on tty->read_wait or tty->write_wait. We test the
1742 * wait queues and kick everyone out _before_ actually starting to
1743 * close. This ensures that we won't block while releasing the tty
1746 * The test for the o_tty closing is necessary, since the master and
1747 * slave sides may close in any order. If the slave side closes out
1748 * first, its count will be one, since the master side holds an open.
1749 * Thus this test wouldn't be triggered at the time the slave closes,
1752 * Note that it's possible for the tty to be opened again while we're
1753 * flushing out waiters. By recalculating the closing flags before
1754 * each iteration we avoid any problems.
1757 /* Guard against races with tty->count changes elsewhere and
1758 opens on /dev/tty */
1760 mutex_lock(&tty_mutex);
1761 tty_lock_pair(tty, o_tty);
1762 tty_closing = tty->count <= 1;
1763 o_tty_closing = o_tty &&
1764 (o_tty->count <= (pty_master ? 1 : 0));
1768 if (waitqueue_active(&tty->read_wait)) {
1769 wake_up_poll(&tty->read_wait, POLLIN);
1772 if (waitqueue_active(&tty->write_wait)) {
1773 wake_up_poll(&tty->write_wait, POLLOUT);
1777 if (o_tty_closing) {
1778 if (waitqueue_active(&o_tty->read_wait)) {
1779 wake_up_poll(&o_tty->read_wait, POLLIN);
1782 if (waitqueue_active(&o_tty->write_wait)) {
1783 wake_up_poll(&o_tty->write_wait, POLLOUT);
1790 printk(KERN_WARNING "%s: %s: read/write wait queue active!\n",
1791 __func__, tty_name(tty, buf));
1792 tty_unlock_pair(tty, o_tty);
1793 mutex_unlock(&tty_mutex);
1798 * The closing flags are now consistent with the open counts on
1799 * both sides, and we've completed the last operation that could
1800 * block, so it's safe to proceed with closing.
1802 * We must *not* drop the tty_mutex until we ensure that a further
1803 * entry into tty_open can not pick up this tty.
1806 if (--o_tty->count < 0) {
1807 printk(KERN_WARNING "%s: bad pty slave count (%d) for %s\n",
1808 __func__, o_tty->count, tty_name(o_tty, buf));
1812 if (--tty->count < 0) {
1813 printk(KERN_WARNING "%s: bad tty->count (%d) for %s\n",
1814 __func__, tty->count, tty_name(tty, buf));
1819 * We've decremented tty->count, so we need to remove this file
1820 * descriptor off the tty->tty_files list; this serves two
1822 * - check_tty_count sees the correct number of file descriptors
1823 * associated with this tty.
1824 * - do_tty_hangup no longer sees this file descriptor as
1825 * something that needs to be handled for hangups.
1830 * Perform some housekeeping before deciding whether to return.
1832 * Set the TTY_CLOSING flag if this was the last open. In the
1833 * case of a pty we may have to wait around for the other side
1834 * to close, and TTY_CLOSING makes sure we can't be reopened.
1837 set_bit(TTY_CLOSING, &tty->flags);
1839 set_bit(TTY_CLOSING, &o_tty->flags);
1842 * If _either_ side is closing, make sure there aren't any
1843 * processes that still think tty or o_tty is their controlling
1846 if (tty_closing || o_tty_closing) {
1847 read_lock(&tasklist_lock);
1848 session_clear_tty(tty->session);
1850 session_clear_tty(o_tty->session);
1851 read_unlock(&tasklist_lock);
1854 mutex_unlock(&tty_mutex);
1855 tty_unlock_pair(tty, o_tty);
1856 /* At this point the TTY_CLOSING flag should ensure a dead tty
1857 cannot be re-opened by a racing opener */
1859 /* check whether both sides are closing ... */
1860 if (!tty_closing || (o_tty && !o_tty_closing))
1863 #ifdef TTY_DEBUG_HANGUP
1864 printk(KERN_DEBUG "%s: %s: final close\n", __func__, tty_name(tty, buf));
1867 * Ask the line discipline code to release its structures
1869 tty_ldisc_release(tty, o_tty);
1871 /* Wait for pending work before tty destruction commmences */
1872 tty_flush_works(tty);
1874 tty_flush_works(o_tty);
1876 #ifdef TTY_DEBUG_HANGUP
1877 printk(KERN_DEBUG "%s: %s: freeing structure...\n", __func__, tty_name(tty, buf));
1880 * The release_tty function takes care of the details of clearing
1881 * the slots and preserving the termios structure. The tty_unlock_pair
1882 * should be safe as we keep a kref while the tty is locked (so the
1883 * unlock never unlocks a freed tty).
1885 mutex_lock(&tty_mutex);
1886 release_tty(tty, idx);
1887 mutex_unlock(&tty_mutex);
1893 * tty_open_current_tty - get tty of current task for open
1894 * @device: device number
1895 * @filp: file pointer to tty
1896 * @return: tty of the current task iff @device is /dev/tty
1898 * We cannot return driver and index like for the other nodes because
1899 * devpts will not work then. It expects inodes to be from devpts FS.
1901 * We need to move to returning a refcounted object from all the lookup
1902 * paths including this one.
1904 static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
1906 struct tty_struct *tty;
1908 if (device != MKDEV(TTYAUX_MAJOR, 0))
1911 tty = get_current_tty();
1913 return ERR_PTR(-ENXIO);
1915 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1918 /* FIXME: we put a reference and return a TTY! */
1919 /* This is only safe because the caller holds tty_mutex */
1924 * tty_lookup_driver - lookup a tty driver for a given device file
1925 * @device: device number
1926 * @filp: file pointer to tty
1927 * @noctty: set if the device should not become a controlling tty
1928 * @index: index for the device in the @return driver
1929 * @return: driver for this inode (with increased refcount)
1931 * If @return is not erroneous, the caller is responsible to decrement the
1932 * refcount by tty_driver_kref_put.
1934 * Locking: tty_mutex protects get_tty_driver
1936 static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
1937 int *noctty, int *index)
1939 struct tty_driver *driver;
1943 case MKDEV(TTY_MAJOR, 0): {
1944 extern struct tty_driver *console_driver;
1945 driver = tty_driver_kref_get(console_driver);
1946 *index = fg_console;
1951 case MKDEV(TTYAUX_MAJOR, 1): {
1952 struct tty_driver *console_driver = console_device(index);
1953 if (console_driver) {
1954 driver = tty_driver_kref_get(console_driver);
1956 /* Don't let /dev/console block */
1957 filp->f_flags |= O_NONBLOCK;
1962 return ERR_PTR(-ENODEV);
1965 driver = get_tty_driver(device, index);
1967 return ERR_PTR(-ENODEV);
1974 * tty_open - open a tty device
1975 * @inode: inode of device file
1976 * @filp: file pointer to tty
1978 * tty_open and tty_release keep up the tty count that contains the
1979 * number of opens done on a tty. We cannot use the inode-count, as
1980 * different inodes might point to the same tty.
1982 * Open-counting is needed for pty masters, as well as for keeping
1983 * track of serial lines: DTR is dropped when the last close happens.
1984 * (This is not done solely through tty->count, now. - Ted 1/27/92)
1986 * The termios state of a pty is reset on first open so that
1987 * settings don't persist across reuse.
1989 * Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.
1990 * tty->count should protect the rest.
1991 * ->siglock protects ->signal/->sighand
1993 * Note: the tty_unlock/lock cases without a ref are only safe due to
1997 static int tty_open(struct inode *inode, struct file *filp)
1999 struct tty_struct *tty;
2001 struct tty_driver *driver = NULL;
2003 dev_t device = inode->i_rdev;
2004 unsigned saved_flags = filp->f_flags;
2006 nonseekable_open(inode, filp);
2009 retval = tty_alloc_file(filp);
2013 noctty = filp->f_flags & O_NOCTTY;
2017 mutex_lock(&tty_mutex);
2018 /* This is protected by the tty_mutex */
2019 tty = tty_open_current_tty(device, filp);
2021 retval = PTR_ERR(tty);
2024 driver = tty_lookup_driver(device, filp, &noctty, &index);
2025 if (IS_ERR(driver)) {
2026 retval = PTR_ERR(driver);
2030 /* check whether we're reopening an existing tty */
2031 tty = tty_driver_lookup_tty(driver, inode, index);
2033 retval = PTR_ERR(tty);
2040 retval = tty_reopen(tty);
2043 tty = ERR_PTR(retval);
2045 } else /* Returns with the tty_lock held for now */
2046 tty = tty_init_dev(driver, index);
2048 mutex_unlock(&tty_mutex);
2050 tty_driver_kref_put(driver);
2052 retval = PTR_ERR(tty);
2056 tty_add_file(tty, filp);
2058 check_tty_count(tty, __func__);
2059 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2060 tty->driver->subtype == PTY_TYPE_MASTER)
2062 #ifdef TTY_DEBUG_HANGUP
2063 printk(KERN_DEBUG "%s: opening %s...\n", __func__, tty->name);
2066 retval = tty->ops->open(tty, filp);
2069 filp->f_flags = saved_flags;
2071 if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) &&
2072 !capable(CAP_SYS_ADMIN))
2076 #ifdef TTY_DEBUG_HANGUP
2077 printk(KERN_DEBUG "%s: error %d in opening %s...\n", __func__,
2080 tty_unlock(tty); /* need to call tty_release without BTM */
2081 tty_release(inode, filp);
2082 if (retval != -ERESTARTSYS)
2085 if (signal_pending(current))
2090 * Need to reset f_op in case a hangup happened.
2092 if (filp->f_op == &hung_up_tty_fops)
2093 filp->f_op = &tty_fops;
2096 clear_bit(TTY_HUPPED, &tty->flags);
2100 mutex_lock(&tty_mutex);
2102 spin_lock_irq(¤t->sighand->siglock);
2104 current->signal->leader &&
2105 !current->signal->tty &&
2106 tty->session == NULL)
2107 __proc_set_tty(current, tty);
2108 spin_unlock_irq(¤t->sighand->siglock);
2110 mutex_unlock(&tty_mutex);
2113 mutex_unlock(&tty_mutex);
2114 /* after locks to avoid deadlock */
2115 if (!IS_ERR_OR_NULL(driver))
2116 tty_driver_kref_put(driver);
2118 tty_free_file(filp);
2125 * tty_poll - check tty status
2126 * @filp: file being polled
2127 * @wait: poll wait structures to update
2129 * Call the line discipline polling method to obtain the poll
2130 * status of the device.
2132 * Locking: locks called line discipline but ldisc poll method
2133 * may be re-entered freely by other callers.
2136 static unsigned int tty_poll(struct file *filp, poll_table *wait)
2138 struct tty_struct *tty = file_tty(filp);
2139 struct tty_ldisc *ld;
2142 if (tty_paranoia_check(tty, file_inode(filp), "tty_poll"))
2145 ld = tty_ldisc_ref_wait(tty);
2147 ret = (ld->ops->poll)(tty, filp, wait);
2148 tty_ldisc_deref(ld);
2152 static int __tty_fasync(int fd, struct file *filp, int on)
2154 struct tty_struct *tty = file_tty(filp);
2155 struct tty_ldisc *ldisc;
2156 unsigned long flags;
2159 if (tty_paranoia_check(tty, file_inode(filp), "tty_fasync"))
2162 retval = fasync_helper(fd, filp, on, &tty->fasync);
2166 ldisc = tty_ldisc_ref(tty);
2168 if (ldisc->ops->fasync)
2169 ldisc->ops->fasync(tty, on);
2170 tty_ldisc_deref(ldisc);
2177 spin_lock_irqsave(&tty->ctrl_lock, flags);
2180 type = PIDTYPE_PGID;
2182 pid = task_pid(current);
2186 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2187 __f_setown(filp, pid, type, 0);
2195 static int tty_fasync(int fd, struct file *filp, int on)
2197 struct tty_struct *tty = file_tty(filp);
2201 retval = __tty_fasync(fd, filp, on);
2208 * tiocsti - fake input character
2209 * @tty: tty to fake input into
2210 * @p: pointer to character
2212 * Fake input to a tty device. Does the necessary locking and
2215 * FIXME: does not honour flow control ??
2218 * Called functions take tty_ldiscs_lock
2219 * current->signal->tty check is safe without locks
2221 * FIXME: may race normal receive processing
2224 static int tiocsti(struct tty_struct *tty, char __user *p)
2227 struct tty_ldisc *ld;
2229 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2231 if (get_user(ch, p))
2233 tty_audit_tiocsti(tty, ch);
2234 ld = tty_ldisc_ref_wait(tty);
2235 ld->ops->receive_buf(tty, &ch, &mbz, 1);
2236 tty_ldisc_deref(ld);
2241 * tiocgwinsz - implement window query ioctl
2243 * @arg: user buffer for result
2245 * Copies the kernel idea of the window size into the user buffer.
2247 * Locking: tty->winsize_mutex is taken to ensure the winsize data
2251 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2255 mutex_lock(&tty->winsize_mutex);
2256 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2257 mutex_unlock(&tty->winsize_mutex);
2259 return err ? -EFAULT: 0;
2263 * tty_do_resize - resize event
2264 * @tty: tty being resized
2265 * @rows: rows (character)
2266 * @cols: cols (character)
2268 * Update the termios variables and send the necessary signals to
2269 * peform a terminal resize correctly
2272 int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
2275 unsigned long flags;
2278 mutex_lock(&tty->winsize_mutex);
2279 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
2281 /* Get the PID values and reference them so we can
2282 avoid holding the tty ctrl lock while sending signals */
2283 spin_lock_irqsave(&tty->ctrl_lock, flags);
2284 pgrp = get_pid(tty->pgrp);
2285 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2288 kill_pgrp(pgrp, SIGWINCH, 1);
2293 mutex_unlock(&tty->winsize_mutex);
2296 EXPORT_SYMBOL(tty_do_resize);
2299 * tiocswinsz - implement window size set ioctl
2300 * @tty; tty side of tty
2301 * @arg: user buffer for result
2303 * Copies the user idea of the window size to the kernel. Traditionally
2304 * this is just advisory information but for the Linux console it
2305 * actually has driver level meaning and triggers a VC resize.
2308 * Driver dependent. The default do_resize method takes the
2309 * tty termios mutex and ctrl_lock. The console takes its own lock
2310 * then calls into the default method.
2313 static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
2315 struct winsize tmp_ws;
2316 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2319 if (tty->ops->resize)
2320 return tty->ops->resize(tty, &tmp_ws);
2322 return tty_do_resize(tty, &tmp_ws);
2326 * tioccons - allow admin to move logical console
2327 * @file: the file to become console
2329 * Allow the administrator to move the redirected console device
2331 * Locking: uses redirect_lock to guard the redirect information
2334 static int tioccons(struct file *file)
2336 if (!capable(CAP_SYS_ADMIN))
2338 if (file->f_op->write == redirected_tty_write) {
2340 spin_lock(&redirect_lock);
2343 spin_unlock(&redirect_lock);
2348 spin_lock(&redirect_lock);
2350 spin_unlock(&redirect_lock);
2353 redirect = get_file(file);
2354 spin_unlock(&redirect_lock);
2359 * fionbio - non blocking ioctl
2360 * @file: file to set blocking value
2361 * @p: user parameter
2363 * Historical tty interfaces had a blocking control ioctl before
2364 * the generic functionality existed. This piece of history is preserved
2365 * in the expected tty API of posix OS's.
2367 * Locking: none, the open file handle ensures it won't go away.
2370 static int fionbio(struct file *file, int __user *p)
2374 if (get_user(nonblock, p))
2377 spin_lock(&file->f_lock);
2379 file->f_flags |= O_NONBLOCK;
2381 file->f_flags &= ~O_NONBLOCK;
2382 spin_unlock(&file->f_lock);
2387 * tiocsctty - set controlling tty
2388 * @tty: tty structure
2389 * @arg: user argument
2391 * This ioctl is used to manage job control. It permits a session
2392 * leader to set this tty as the controlling tty for the session.
2395 * Takes tty_mutex() to protect tty instance
2396 * Takes tasklist_lock internally to walk sessions
2397 * Takes ->siglock() when updating signal->tty
2400 static int tiocsctty(struct tty_struct *tty, int arg)
2403 if (current->signal->leader && (task_session(current) == tty->session))
2406 mutex_lock(&tty_mutex);
2408 * The process must be a session leader and
2409 * not have a controlling tty already.
2411 if (!current->signal->leader || current->signal->tty) {
2418 * This tty is already the controlling
2419 * tty for another session group!
2421 if (arg == 1 && capable(CAP_SYS_ADMIN)) {
2425 read_lock(&tasklist_lock);
2426 session_clear_tty(tty->session);
2427 read_unlock(&tasklist_lock);
2433 proc_set_tty(current, tty);
2435 mutex_unlock(&tty_mutex);
2440 * tty_get_pgrp - return a ref counted pgrp pid
2443 * Returns a refcounted instance of the pid struct for the process
2444 * group controlling the tty.
2447 struct pid *tty_get_pgrp(struct tty_struct *tty)
2449 unsigned long flags;
2452 spin_lock_irqsave(&tty->ctrl_lock, flags);
2453 pgrp = get_pid(tty->pgrp);
2454 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2458 EXPORT_SYMBOL_GPL(tty_get_pgrp);
2461 * tiocgpgrp - get process group
2462 * @tty: tty passed by user
2463 * @real_tty: tty side of the tty passed by the user if a pty else the tty
2466 * Obtain the process group of the tty. If there is no process group
2469 * Locking: none. Reference to current->signal->tty is safe.
2472 static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2477 * (tty == real_tty) is a cheap way of
2478 * testing if the tty is NOT a master pty.
2480 if (tty == real_tty && current->signal->tty != real_tty)
2482 pid = tty_get_pgrp(real_tty);
2483 ret = put_user(pid_vnr(pid), p);
2489 * tiocspgrp - attempt to set process group
2490 * @tty: tty passed by user
2491 * @real_tty: tty side device matching tty passed by user
2494 * Set the process group of the tty to the session passed. Only
2495 * permitted where the tty session is our session.
2497 * Locking: RCU, ctrl lock
2500 static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2504 int retval = tty_check_change(real_tty);
2505 unsigned long flags;
2511 if (!current->signal->tty ||
2512 (current->signal->tty != real_tty) ||
2513 (real_tty->session != task_session(current)))
2515 if (get_user(pgrp_nr, p))
2520 pgrp = find_vpid(pgrp_nr);
2525 if (session_of_pgrp(pgrp) != task_session(current))
2528 spin_lock_irqsave(&tty->ctrl_lock, flags);
2529 put_pid(real_tty->pgrp);
2530 real_tty->pgrp = get_pid(pgrp);
2531 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2538 * tiocgsid - get session id
2539 * @tty: tty passed by user
2540 * @real_tty: tty side of the tty passed by the user if a pty else the tty
2541 * @p: pointer to returned session id
2543 * Obtain the session id of the tty. If there is no session
2546 * Locking: none. Reference to current->signal->tty is safe.
2549 static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2552 * (tty == real_tty) is a cheap way of
2553 * testing if the tty is NOT a master pty.
2555 if (tty == real_tty && current->signal->tty != real_tty)
2557 if (!real_tty->session)
2559 return put_user(pid_vnr(real_tty->session), p);
2563 * tiocsetd - set line discipline
2565 * @p: pointer to user data
2567 * Set the line discipline according to user request.
2569 * Locking: see tty_set_ldisc, this function is just a helper
2572 static int tiocsetd(struct tty_struct *tty, int __user *p)
2577 if (get_user(ldisc, p))
2580 ret = tty_set_ldisc(tty, ldisc);
2586 * send_break - performed time break
2587 * @tty: device to break on
2588 * @duration: timeout in mS
2590 * Perform a timed break on hardware that lacks its own driver level
2591 * timed break functionality.
2594 * atomic_write_lock serializes
2598 static int send_break(struct tty_struct *tty, unsigned int duration)
2602 if (tty->ops->break_ctl == NULL)
2605 if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2606 retval = tty->ops->break_ctl(tty, duration);
2608 /* Do the work ourselves */
2609 if (tty_write_lock(tty, 0) < 0)
2611 retval = tty->ops->break_ctl(tty, -1);
2614 if (!signal_pending(current))
2615 msleep_interruptible(duration);
2616 retval = tty->ops->break_ctl(tty, 0);
2618 tty_write_unlock(tty);
2619 if (signal_pending(current))
2626 * tty_tiocmget - get modem status
2628 * @file: user file pointer
2629 * @p: pointer to result
2631 * Obtain the modem status bits from the tty driver if the feature
2632 * is supported. Return -EINVAL if it is not available.
2634 * Locking: none (up to the driver)
2637 static int tty_tiocmget(struct tty_struct *tty, int __user *p)
2639 int retval = -EINVAL;
2641 if (tty->ops->tiocmget) {
2642 retval = tty->ops->tiocmget(tty);
2645 retval = put_user(retval, p);
2651 * tty_tiocmset - set modem status
2653 * @cmd: command - clear bits, set bits or set all
2654 * @p: pointer to desired bits
2656 * Set the modem status bits from the tty driver if the feature
2657 * is supported. Return -EINVAL if it is not available.
2659 * Locking: none (up to the driver)
2662 static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
2666 unsigned int set, clear, val;
2668 if (tty->ops->tiocmset == NULL)
2671 retval = get_user(val, p);
2687 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2688 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2689 return tty->ops->tiocmset(tty, set, clear);
2692 static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
2694 int retval = -EINVAL;
2695 struct serial_icounter_struct icount;
2696 memset(&icount, 0, sizeof(icount));
2697 if (tty->ops->get_icount)
2698 retval = tty->ops->get_icount(tty, &icount);
2701 if (copy_to_user(arg, &icount, sizeof(icount)))
2706 struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
2708 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2709 tty->driver->subtype == PTY_TYPE_MASTER)
2713 EXPORT_SYMBOL(tty_pair_get_tty);
2715 struct tty_struct *tty_pair_get_pty(struct tty_struct *tty)
2717 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2718 tty->driver->subtype == PTY_TYPE_MASTER)
2722 EXPORT_SYMBOL(tty_pair_get_pty);
2725 * Split this up, as gcc can choke on it otherwise..
2727 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2729 struct tty_struct *tty = file_tty(file);
2730 struct tty_struct *real_tty;
2731 void __user *p = (void __user *)arg;
2733 struct tty_ldisc *ld;
2735 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2738 real_tty = tty_pair_get_tty(tty);
2741 * Factor out some common prep work
2749 retval = tty_check_change(tty);
2752 if (cmd != TIOCCBRK) {
2753 tty_wait_until_sent(tty, 0);
2754 if (signal_pending(current))
2765 return tiocsti(tty, p);
2767 return tiocgwinsz(real_tty, p);
2769 return tiocswinsz(real_tty, p);
2771 return real_tty != tty ? -EINVAL : tioccons(file);
2773 return fionbio(file, p);
2775 set_bit(TTY_EXCLUSIVE, &tty->flags);
2778 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2782 int excl = test_bit(TTY_EXCLUSIVE, &tty->flags);
2783 return put_user(excl, (int __user *)p);
2786 if (current->signal->tty != tty)
2791 return tiocsctty(tty, arg);
2793 return tiocgpgrp(tty, real_tty, p);
2795 return tiocspgrp(tty, real_tty, p);
2797 return tiocgsid(tty, real_tty, p);
2799 return put_user(tty->ldisc->ops->num, (int __user *)p);
2801 return tiocsetd(tty, p);
2803 if (!capable(CAP_SYS_ADMIN))
2809 unsigned int ret = new_encode_dev(tty_devnum(real_tty));
2810 return put_user(ret, (unsigned int __user *)p);
2815 case TIOCSBRK: /* Turn break on, unconditionally */
2816 if (tty->ops->break_ctl)
2817 return tty->ops->break_ctl(tty, -1);
2819 case TIOCCBRK: /* Turn break off, unconditionally */
2820 if (tty->ops->break_ctl)
2821 return tty->ops->break_ctl(tty, 0);
2823 case TCSBRK: /* SVID version: non-zero arg --> no break */
2824 /* non-zero arg means wait for all output data
2825 * to be sent (performed above) but don't send break.
2826 * This is used by the tcdrain() termios function.
2829 return send_break(tty, 250);
2831 case TCSBRKP: /* support for POSIX tcsendbreak() */
2832 return send_break(tty, arg ? arg*100 : 250);
2835 return tty_tiocmget(tty, p);
2839 return tty_tiocmset(tty, cmd, p);
2841 retval = tty_tiocgicount(tty, p);
2842 /* For the moment allow fall through to the old method */
2843 if (retval != -EINVAL)
2850 /* flush tty buffer and allow ldisc to process ioctl */
2851 tty_buffer_flush(tty);
2856 if (tty->ops->ioctl) {
2857 retval = (tty->ops->ioctl)(tty, cmd, arg);
2858 if (retval != -ENOIOCTLCMD)
2861 ld = tty_ldisc_ref_wait(tty);
2863 if (ld->ops->ioctl) {
2864 retval = ld->ops->ioctl(tty, file, cmd, arg);
2865 if (retval == -ENOIOCTLCMD)
2868 tty_ldisc_deref(ld);
2872 #ifdef CONFIG_COMPAT
2873 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2876 struct tty_struct *tty = file_tty(file);
2877 struct tty_ldisc *ld;
2878 int retval = -ENOIOCTLCMD;
2880 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2883 if (tty->ops->compat_ioctl) {
2884 retval = (tty->ops->compat_ioctl)(tty, cmd, arg);
2885 if (retval != -ENOIOCTLCMD)
2889 ld = tty_ldisc_ref_wait(tty);
2890 if (ld->ops->compat_ioctl)
2891 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
2893 retval = n_tty_compat_ioctl_helper(tty, file, cmd, arg);
2894 tty_ldisc_deref(ld);
2900 static int this_tty(const void *t, struct file *file, unsigned fd)
2902 if (likely(file->f_op->read != tty_read))
2904 return file_tty(file) != t ? 0 : fd + 1;
2908 * This implements the "Secure Attention Key" --- the idea is to
2909 * prevent trojan horses by killing all processes associated with this
2910 * tty when the user hits the "Secure Attention Key". Required for
2911 * super-paranoid applications --- see the Orange Book for more details.
2913 * This code could be nicer; ideally it should send a HUP, wait a few
2914 * seconds, then send a INT, and then a KILL signal. But you then
2915 * have to coordinate with the init process, since all processes associated
2916 * with the current tty must be dead before the new getty is allowed
2919 * Now, if it would be correct ;-/ The current code has a nasty hole -
2920 * it doesn't catch files in flight. We may send the descriptor to ourselves
2921 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
2923 * Nasty bug: do_SAK is being called in interrupt context. This can
2924 * deadlock. We punt it up to process context. AKPM - 16Mar2001
2926 void __do_SAK(struct tty_struct *tty)
2931 struct task_struct *g, *p;
2932 struct pid *session;
2937 session = tty->session;
2939 tty_ldisc_flush(tty);
2941 tty_driver_flush_buffer(tty);
2943 read_lock(&tasklist_lock);
2944 /* Kill the entire session */
2945 do_each_pid_task(session, PIDTYPE_SID, p) {
2946 printk(KERN_NOTICE "SAK: killed process %d"
2947 " (%s): task_session(p)==tty->session\n",
2948 task_pid_nr(p), p->comm);
2949 send_sig(SIGKILL, p, 1);
2950 } while_each_pid_task(session, PIDTYPE_SID, p);
2951 /* Now kill any processes that happen to have the
2954 do_each_thread(g, p) {
2955 if (p->signal->tty == tty) {
2956 printk(KERN_NOTICE "SAK: killed process %d"
2957 " (%s): task_session(p)==tty->session\n",
2958 task_pid_nr(p), p->comm);
2959 send_sig(SIGKILL, p, 1);
2963 i = iterate_fd(p->files, 0, this_tty, tty);
2965 printk(KERN_NOTICE "SAK: killed process %d"
2966 " (%s): fd#%d opened to the tty\n",
2967 task_pid_nr(p), p->comm, i - 1);
2968 force_sig(SIGKILL, p);
2971 } while_each_thread(g, p);
2972 read_unlock(&tasklist_lock);
2976 static void do_SAK_work(struct work_struct *work)
2978 struct tty_struct *tty =
2979 container_of(work, struct tty_struct, SAK_work);
2984 * The tq handling here is a little racy - tty->SAK_work may already be queued.
2985 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
2986 * the values which we write to it will be identical to the values which it
2987 * already has. --akpm
2989 void do_SAK(struct tty_struct *tty)
2993 schedule_work(&tty->SAK_work);
2996 EXPORT_SYMBOL(do_SAK);
2998 static int dev_match_devt(struct device *dev, const void *data)
3000 const dev_t *devt = data;
3001 return dev->devt == *devt;
3004 /* Must put_device() after it's unused! */
3005 static struct device *tty_get_device(struct tty_struct *tty)
3007 dev_t devt = tty_devnum(tty);
3008 return class_find_device(tty_class, NULL, &devt, dev_match_devt);
3015 * This subroutine allocates and initializes a tty structure.
3017 * Locking: none - tty in question is not exposed at this point
3020 struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
3022 struct tty_struct *tty;
3024 tty = kzalloc(sizeof(*tty), GFP_KERNEL);
3028 kref_init(&tty->kref);
3029 tty->magic = TTY_MAGIC;
3030 tty_ldisc_init(tty);
3031 tty->session = NULL;
3033 mutex_init(&tty->legacy_mutex);
3034 mutex_init(&tty->throttle_mutex);
3035 init_rwsem(&tty->termios_rwsem);
3036 mutex_init(&tty->winsize_mutex);
3037 init_ldsem(&tty->ldisc_sem);
3038 init_waitqueue_head(&tty->write_wait);
3039 init_waitqueue_head(&tty->read_wait);
3040 INIT_WORK(&tty->hangup_work, do_tty_hangup);
3041 mutex_init(&tty->atomic_write_lock);
3042 spin_lock_init(&tty->ctrl_lock);
3043 spin_lock_init(&tty->flow_lock);
3044 INIT_LIST_HEAD(&tty->tty_files);
3045 INIT_WORK(&tty->SAK_work, do_SAK_work);
3047 tty->driver = driver;
3048 tty->ops = driver->ops;
3050 tty_line_name(driver, idx, tty->name);
3051 tty->dev = tty_get_device(tty);
3057 * deinitialize_tty_struct
3058 * @tty: tty to deinitialize
3060 * This subroutine deinitializes a tty structure that has been newly
3061 * allocated but tty_release cannot be called on that yet.
3063 * Locking: none - tty in question must not be exposed at this point
3065 void deinitialize_tty_struct(struct tty_struct *tty)
3067 tty_ldisc_deinit(tty);
3071 * tty_put_char - write one character to a tty
3075 * Write one byte to the tty using the provided put_char method
3076 * if present. Returns the number of characters successfully output.
3078 * Note: the specific put_char operation in the driver layer may go
3079 * away soon. Don't call it directly, use this method
3082 int tty_put_char(struct tty_struct *tty, unsigned char ch)
3084 if (tty->ops->put_char)
3085 return tty->ops->put_char(tty, ch);
3086 return tty->ops->write(tty, &ch, 1);
3088 EXPORT_SYMBOL_GPL(tty_put_char);
3090 struct class *tty_class;
3092 static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
3093 unsigned int index, unsigned int count)
3095 /* init here, since reused cdevs cause crashes */
3096 cdev_init(&driver->cdevs[index], &tty_fops);
3097 driver->cdevs[index].owner = driver->owner;
3098 return cdev_add(&driver->cdevs[index], dev, count);
3102 * tty_register_device - register a tty device
3103 * @driver: the tty driver that describes the tty device
3104 * @index: the index in the tty driver for this tty device
3105 * @device: a struct device that is associated with this tty device.
3106 * This field is optional, if there is no known struct device
3107 * for this tty device it can be set to NULL safely.
3109 * Returns a pointer to the struct device for this tty device
3110 * (or ERR_PTR(-EFOO) on error).
3112 * This call is required to be made to register an individual tty device
3113 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3114 * that bit is not set, this function should not be called by a tty
3120 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
3121 struct device *device)
3123 return tty_register_device_attr(driver, index, device, NULL, NULL);
3125 EXPORT_SYMBOL(tty_register_device);
3127 static void tty_device_create_release(struct device *dev)
3129 pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
3134 * tty_register_device_attr - register a tty device
3135 * @driver: the tty driver that describes the tty device
3136 * @index: the index in the tty driver for this tty device
3137 * @device: a struct device that is associated with this tty device.
3138 * This field is optional, if there is no known struct device
3139 * for this tty device it can be set to NULL safely.
3140 * @drvdata: Driver data to be set to device.
3141 * @attr_grp: Attribute group to be set on device.
3143 * Returns a pointer to the struct device for this tty device
3144 * (or ERR_PTR(-EFOO) on error).
3146 * This call is required to be made to register an individual tty device
3147 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3148 * that bit is not set, this function should not be called by a tty
3153 struct device *tty_register_device_attr(struct tty_driver *driver,
3154 unsigned index, struct device *device,
3156 const struct attribute_group **attr_grp)
3159 dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
3160 struct device *dev = NULL;
3161 int retval = -ENODEV;
3164 if (index >= driver->num) {
3165 printk(KERN_ERR "Attempt to register invalid tty line number "
3167 return ERR_PTR(-EINVAL);
3170 if (driver->type == TTY_DRIVER_TYPE_PTY)
3171 pty_line_name(driver, index, name);
3173 tty_line_name(driver, index, name);
3175 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3176 retval = tty_cdev_add(driver, devt, index, 1);
3182 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
3189 dev->class = tty_class;
3190 dev->parent = device;
3191 dev->release = tty_device_create_release;
3192 dev_set_name(dev, "%s", name);
3193 dev->groups = attr_grp;
3194 dev_set_drvdata(dev, drvdata);
3196 retval = device_register(dev);
3205 cdev_del(&driver->cdevs[index]);
3206 return ERR_PTR(retval);
3208 EXPORT_SYMBOL_GPL(tty_register_device_attr);
3211 * tty_unregister_device - unregister a tty device
3212 * @driver: the tty driver that describes the tty device
3213 * @index: the index in the tty driver for this tty device
3215 * If a tty device is registered with a call to tty_register_device() then
3216 * this function must be called when the tty device is gone.
3221 void tty_unregister_device(struct tty_driver *driver, unsigned index)
3223 device_destroy(tty_class,
3224 MKDEV(driver->major, driver->minor_start) + index);
3225 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC))
3226 cdev_del(&driver->cdevs[index]);
3228 EXPORT_SYMBOL(tty_unregister_device);
3231 * __tty_alloc_driver -- allocate tty driver
3232 * @lines: count of lines this driver can handle at most
3233 * @owner: module which is repsonsible for this driver
3234 * @flags: some of TTY_DRIVER_* flags, will be set in driver->flags
3236 * This should not be called directly, some of the provided macros should be
3237 * used instead. Use IS_ERR and friends on @retval.
3239 struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
3240 unsigned long flags)
3242 struct tty_driver *driver;
3243 unsigned int cdevs = 1;
3246 if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
3247 return ERR_PTR(-EINVAL);
3249 driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
3251 return ERR_PTR(-ENOMEM);
3253 kref_init(&driver->kref);
3254 driver->magic = TTY_DRIVER_MAGIC;
3255 driver->num = lines;
3256 driver->owner = owner;
3257 driver->flags = flags;
3259 if (!(flags & TTY_DRIVER_DEVPTS_MEM)) {
3260 driver->ttys = kcalloc(lines, sizeof(*driver->ttys),
3262 driver->termios = kcalloc(lines, sizeof(*driver->termios),
3264 if (!driver->ttys || !driver->termios) {
3270 if (!(flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3271 driver->ports = kcalloc(lines, sizeof(*driver->ports),
3273 if (!driver->ports) {
3280 driver->cdevs = kcalloc(cdevs, sizeof(*driver->cdevs), GFP_KERNEL);
3281 if (!driver->cdevs) {
3288 kfree(driver->ports);
3289 kfree(driver->ttys);
3290 kfree(driver->termios);
3292 return ERR_PTR(err);
3294 EXPORT_SYMBOL(__tty_alloc_driver);
3296 static void destruct_tty_driver(struct kref *kref)
3298 struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
3300 struct ktermios *tp;
3302 if (driver->flags & TTY_DRIVER_INSTALLED) {
3304 * Free the termios and termios_locked structures because
3305 * we don't want to get memory leaks when modular tty
3306 * drivers are removed from the kernel.
3308 for (i = 0; i < driver->num; i++) {
3309 tp = driver->termios[i];
3311 driver->termios[i] = NULL;
3314 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3315 tty_unregister_device(driver, i);
3317 proc_tty_unregister_driver(driver);
3318 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
3319 cdev_del(&driver->cdevs[0]);
3321 kfree(driver->cdevs);
3322 kfree(driver->ports);
3323 kfree(driver->termios);
3324 kfree(driver->ttys);
3328 void tty_driver_kref_put(struct tty_driver *driver)
3330 kref_put(&driver->kref, destruct_tty_driver);
3332 EXPORT_SYMBOL(tty_driver_kref_put);
3334 void tty_set_operations(struct tty_driver *driver,
3335 const struct tty_operations *op)
3339 EXPORT_SYMBOL(tty_set_operations);
3341 void put_tty_driver(struct tty_driver *d)
3343 tty_driver_kref_put(d);
3345 EXPORT_SYMBOL(put_tty_driver);
3348 * Called by a tty driver to register itself.
3350 int tty_register_driver(struct tty_driver *driver)
3357 if (!driver->major) {
3358 error = alloc_chrdev_region(&dev, driver->minor_start,
3359 driver->num, driver->name);
3361 driver->major = MAJOR(dev);
3362 driver->minor_start = MINOR(dev);
3365 dev = MKDEV(driver->major, driver->minor_start);
3366 error = register_chrdev_region(dev, driver->num, driver->name);
3371 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) {
3372 error = tty_cdev_add(driver, dev, 0, driver->num);
3374 goto err_unreg_char;
3377 mutex_lock(&tty_mutex);
3378 list_add(&driver->tty_drivers, &tty_drivers);
3379 mutex_unlock(&tty_mutex);
3381 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
3382 for (i = 0; i < driver->num; i++) {
3383 d = tty_register_device(driver, i, NULL);
3386 goto err_unreg_devs;
3390 proc_tty_register_driver(driver);
3391 driver->flags |= TTY_DRIVER_INSTALLED;
3395 for (i--; i >= 0; i--)
3396 tty_unregister_device(driver, i);
3398 mutex_lock(&tty_mutex);
3399 list_del(&driver->tty_drivers);
3400 mutex_unlock(&tty_mutex);
3403 unregister_chrdev_region(dev, driver->num);
3407 EXPORT_SYMBOL(tty_register_driver);
3410 * Called by a tty driver to unregister itself.
3412 int tty_unregister_driver(struct tty_driver *driver)
3416 if (driver->refcount)
3419 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3421 mutex_lock(&tty_mutex);
3422 list_del(&driver->tty_drivers);
3423 mutex_unlock(&tty_mutex);
3427 EXPORT_SYMBOL(tty_unregister_driver);
3429 dev_t tty_devnum(struct tty_struct *tty)
3431 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3433 EXPORT_SYMBOL(tty_devnum);
3435 void proc_clear_tty(struct task_struct *p)
3437 unsigned long flags;
3438 struct tty_struct *tty;
3439 spin_lock_irqsave(&p->sighand->siglock, flags);
3440 tty = p->signal->tty;
3441 p->signal->tty = NULL;
3442 spin_unlock_irqrestore(&p->sighand->siglock, flags);
3446 /* Called under the sighand lock */
3448 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3451 unsigned long flags;
3452 /* We should not have a session or pgrp to put here but.... */
3453 spin_lock_irqsave(&tty->ctrl_lock, flags);
3454 put_pid(tty->session);
3456 tty->pgrp = get_pid(task_pgrp(tsk));
3457 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
3458 tty->session = get_pid(task_session(tsk));
3459 if (tsk->signal->tty) {
3460 printk(KERN_DEBUG "tty not NULL!!\n");
3461 tty_kref_put(tsk->signal->tty);
3464 put_pid(tsk->signal->tty_old_pgrp);
3465 tsk->signal->tty = tty_kref_get(tty);
3466 tsk->signal->tty_old_pgrp = NULL;
3469 static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3471 spin_lock_irq(&tsk->sighand->siglock);
3472 __proc_set_tty(tsk, tty);
3473 spin_unlock_irq(&tsk->sighand->siglock);
3476 struct tty_struct *get_current_tty(void)
3478 struct tty_struct *tty;
3479 unsigned long flags;
3481 spin_lock_irqsave(¤t->sighand->siglock, flags);
3482 tty = tty_kref_get(current->signal->tty);
3483 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
3486 EXPORT_SYMBOL_GPL(get_current_tty);
3488 void tty_default_fops(struct file_operations *fops)
3494 * Initialize the console device. This is called *early*, so
3495 * we can't necessarily depend on lots of kernel help here.
3496 * Just do some early initializations, and do the complex setup
3499 void __init console_init(void)
3503 /* Setup the default TTY line discipline. */
3507 * set up the console device so that later boot sequences can
3508 * inform about problems etc..
3510 call = __con_initcall_start;
3511 while (call < __con_initcall_end) {
3517 static char *tty_devnode(struct device *dev, umode_t *mode)
3521 if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
3522 dev->devt == MKDEV(TTYAUX_MAJOR, 2))
3527 static int __init tty_class_init(void)
3529 tty_class = class_create(THIS_MODULE, "tty");
3530 if (IS_ERR(tty_class))
3531 return PTR_ERR(tty_class);
3532 tty_class->devnode = tty_devnode;
3536 postcore_initcall(tty_class_init);
3538 /* 3/2004 jmc: why do these devices exist? */
3539 static struct cdev tty_cdev, console_cdev;
3541 static ssize_t show_cons_active(struct device *dev,
3542 struct device_attribute *attr, char *buf)
3544 struct console *cs[16];
3550 for_each_console(c) {
3555 if ((c->flags & CON_ENABLED) == 0)
3558 if (i >= ARRAY_SIZE(cs))
3562 int index = cs[i]->index;
3563 struct tty_driver *drv = cs[i]->device(cs[i], &index);
3565 /* don't resolve tty0 as some programs depend on it */
3566 if (drv && (cs[i]->index > 0 || drv->major != TTY_MAJOR))
3567 count += tty_line_name(drv, index, buf + count);
3569 count += sprintf(buf + count, "%s%d",
3570 cs[i]->name, cs[i]->index);
3572 count += sprintf(buf + count, "%c", i ? ' ':'\n');
3578 static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
3580 static struct device *consdev;
3582 void console_sysfs_notify(void)
3585 sysfs_notify(&consdev->kobj, NULL, "active");
3589 * Ok, now we can initialize the rest of the tty devices and can count
3590 * on memory allocations, interrupts etc..
3592 int __init tty_init(void)
3594 cdev_init(&tty_cdev, &tty_fops);
3595 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3596 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3597 panic("Couldn't register /dev/tty driver\n");
3598 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
3600 cdev_init(&console_cdev, &console_fops);
3601 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3602 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3603 panic("Couldn't register /dev/console driver\n");
3604 consdev = device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 1), NULL,
3606 if (IS_ERR(consdev))
3609 WARN_ON(device_create_file(consdev, &dev_attr_active) < 0);
3612 vty_init(&console_fops);