1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 1991, 1992 Linus Torvalds
7 * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles
8 * or rs-channels. It also implements echoing, cooked mode etc.
10 * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.
12 * Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the
13 * tty_struct and tty_queue structures. Previously there was an array
14 * of 256 tty_struct's which was statically allocated, and the
15 * tty_queue structures were allocated at boot time. Both are now
16 * dynamically allocated only when the tty is open.
18 * Also restructured routines so that there is more of a separation
19 * between the high-level tty routines (tty_io.c and tty_ioctl.c) and
20 * the low-level tty routines (serial.c, pty.c, console.c). This
21 * makes for cleaner and more compact code. -TYT, 9/17/92
23 * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
24 * which can be dynamically activated and de-activated by the line
25 * discipline handling modules (like SLIP).
27 * NOTE: pay no attention to the line discipline code (yet); its
28 * interface is still subject to change in this version...
31 * Added functionality to the OPOST tty handling. No delays, but all
32 * other bits should be there.
33 * -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993.
35 * Rewrote canonical mode and added more termios flags.
36 * -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94
38 * Reorganized FASYNC support so mouse code can share it.
39 * -- ctm@ardi.com, 9Sep95
41 * New TIOCLINUX variants added.
42 * -- mj@k332.feld.cvut.cz, 19-Nov-95
44 * Restrict vt switching via ioctl()
45 * -- grif@cs.ucr.edu, 5-Dec-95
47 * Move console and virtual terminal code to more appropriate files,
48 * implement CONFIG_VT and generalize console device interface.
49 * -- Marko Kohtala <Marko.Kohtala@hut.fi>, March 97
51 * Rewrote tty_init_dev and tty_release_dev to eliminate races.
52 * -- Bill Hawes <whawes@star.net>, June 97
54 * Added devfs support.
55 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 13-Jan-1998
57 * Added support for a Unix98-style ptmx device.
58 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
60 * Reduced memory usage for older ARM systems
61 * -- Russell King <rmk@arm.linux.org.uk>
63 * Move do_SAK() into process context. Less stack use in devfs functions.
64 * alloc_tty_struct() always uses kmalloc()
65 * -- Andrew Morton <andrewm@uow.edu.eu> 17Mar01
68 #include <linux/types.h>
69 #include <linux/major.h>
70 #include <linux/errno.h>
71 #include <linux/signal.h>
72 #include <linux/fcntl.h>
73 #include <linux/sched/signal.h>
74 #include <linux/sched/task.h>
75 #include <linux/interrupt.h>
76 #include <linux/tty.h>
77 #include <linux/tty_driver.h>
78 #include <linux/tty_flip.h>
79 #include <linux/devpts_fs.h>
80 #include <linux/file.h>
81 #include <linux/fdtable.h>
82 #include <linux/console.h>
83 #include <linux/timer.h>
84 #include <linux/ctype.h>
87 #include <linux/string.h>
88 #include <linux/slab.h>
89 #include <linux/poll.h>
90 #include <linux/proc_fs.h>
91 #include <linux/init.h>
92 #include <linux/module.h>
93 #include <linux/device.h>
94 #include <linux/wait.h>
95 #include <linux/bitops.h>
96 #include <linux/delay.h>
97 #include <linux/seq_file.h>
98 #include <linux/serial.h>
99 #include <linux/ratelimit.h>
100 #include <linux/compat.h>
102 #include <linux/uaccess.h>
104 #include <linux/kbd_kern.h>
105 #include <linux/vt_kern.h>
106 #include <linux/selection.h>
108 #include <linux/kmod.h>
109 #include <linux/nsproxy.h>
111 #undef TTY_DEBUG_HANGUP
112 #ifdef TTY_DEBUG_HANGUP
113 # define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args)
115 # define tty_debug_hangup(tty, f, args...) do { } while (0)
118 #define TTY_PARANOIA_CHECK 1
119 #define CHECK_TTY_COUNT 1
121 struct ktermios tty_std_termios = { /* for the benefit of tty drivers */
122 .c_iflag = ICRNL | IXON,
123 .c_oflag = OPOST | ONLCR,
124 .c_cflag = B38400 | CS8 | CREAD | HUPCL,
125 .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
126 ECHOCTL | ECHOKE | IEXTEN,
130 /* .c_line = N_TTY, */
133 EXPORT_SYMBOL(tty_std_termios);
135 /* This list gets poked at by procfs and various bits of boot up code. This
136 could do with some rationalisation such as pulling the tty proc function
139 LIST_HEAD(tty_drivers); /* linked list of tty drivers */
141 /* Mutex to protect creating and releasing a tty */
142 DEFINE_MUTEX(tty_mutex);
144 static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
145 static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
146 ssize_t redirected_tty_write(struct file *, const char __user *,
148 static __poll_t tty_poll(struct file *, poll_table *);
149 static int tty_open(struct inode *, struct file *);
150 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
152 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
155 #define tty_compat_ioctl NULL
157 static int __tty_fasync(int fd, struct file *filp, int on);
158 static int tty_fasync(int fd, struct file *filp, int on);
159 static void release_tty(struct tty_struct *tty, int idx);
162 * free_tty_struct - free a disused tty
163 * @tty: tty struct to free
165 * Free the write buffers, tty queue and tty memory itself.
167 * Locking: none. Must be called after tty is definitely unused
170 static void free_tty_struct(struct tty_struct *tty)
172 tty_ldisc_deinit(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;
228 struct tty_struct *tty = priv->tty;
230 spin_lock(&tty->files_lock);
231 list_del(&priv->list);
232 spin_unlock(&tty->files_lock);
237 * tty_name - return tty naming
238 * @tty: tty structure
240 * Convert a tty structure into a name. The name reflects the kernel
241 * naming policy and if udev is in use may not reflect user space
246 const char *tty_name(const struct tty_struct *tty)
248 if (!tty) /* Hmm. NULL pointer. That's fun. */
253 EXPORT_SYMBOL(tty_name);
255 const char *tty_driver_name(const struct tty_struct *tty)
257 if (!tty || !tty->driver)
259 return tty->driver->name;
262 static int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
265 #ifdef TTY_PARANOIA_CHECK
267 pr_warn("(%d:%d): %s: NULL tty\n",
268 imajor(inode), iminor(inode), routine);
271 if (tty->magic != TTY_MAGIC) {
272 pr_warn("(%d:%d): %s: bad magic number\n",
273 imajor(inode), iminor(inode), routine);
280 /* Caller must hold tty_lock */
281 static int check_tty_count(struct tty_struct *tty, const char *routine)
283 #ifdef CHECK_TTY_COUNT
285 int count = 0, kopen_count = 0;
287 spin_lock(&tty->files_lock);
288 list_for_each(p, &tty->tty_files) {
291 spin_unlock(&tty->files_lock);
292 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
293 tty->driver->subtype == PTY_TYPE_SLAVE &&
294 tty->link && tty->link->count)
296 if (tty_port_kopened(tty->port))
298 if (tty->count != (count + kopen_count)) {
299 tty_warn(tty, "%s: tty->count(%d) != (#fd's(%d) + #kopen's(%d))\n",
300 routine, tty->count, count, kopen_count);
301 return (count + kopen_count);
308 * get_tty_driver - find device of a tty
309 * @dev_t: device identifier
310 * @index: returns the index of the tty
312 * This routine returns a tty driver structure, given a device number
313 * and also passes back the index number.
315 * Locking: caller must hold tty_mutex
318 static struct tty_driver *get_tty_driver(dev_t device, int *index)
320 struct tty_driver *p;
322 list_for_each_entry(p, &tty_drivers, tty_drivers) {
323 dev_t base = MKDEV(p->major, p->minor_start);
324 if (device < base || device >= base + p->num)
326 *index = device - base;
327 return tty_driver_kref_get(p);
333 * tty_dev_name_to_number - return dev_t for device name
334 * @name: user space name of device under /dev
335 * @number: pointer to dev_t that this function will populate
337 * This function converts device names like ttyS0 or ttyUSB1 into dev_t
338 * like (4, 64) or (188, 1). If no corresponding driver is registered then
339 * the function returns -ENODEV.
341 * Locking: this acquires tty_mutex to protect the tty_drivers list from
342 * being modified while we are traversing it, and makes sure to
343 * release it before exiting.
345 int tty_dev_name_to_number(const char *name, dev_t *number)
347 struct tty_driver *p;
349 int index, prefix_length = 0;
352 for (str = name; *str && !isdigit(*str); str++)
358 ret = kstrtoint(str, 10, &index);
362 prefix_length = str - name;
363 mutex_lock(&tty_mutex);
365 list_for_each_entry(p, &tty_drivers, tty_drivers)
366 if (prefix_length == strlen(p->name) && strncmp(name,
367 p->name, prefix_length) == 0) {
368 if (index < p->num) {
369 *number = MKDEV(p->major, p->minor_start + index);
374 /* if here then driver wasn't found */
377 mutex_unlock(&tty_mutex);
380 EXPORT_SYMBOL_GPL(tty_dev_name_to_number);
382 #ifdef CONFIG_CONSOLE_POLL
385 * tty_find_polling_driver - find device of a polled tty
386 * @name: name string to match
387 * @line: pointer to resulting tty line nr
389 * This routine returns a tty driver structure, given a name
390 * and the condition that the tty driver is capable of polled
393 struct tty_driver *tty_find_polling_driver(char *name, int *line)
395 struct tty_driver *p, *res = NULL;
400 for (str = name; *str; str++)
401 if ((*str >= '0' && *str <= '9') || *str == ',')
407 tty_line = simple_strtoul(str, &str, 10);
409 mutex_lock(&tty_mutex);
410 /* Search through the tty devices to look for a match */
411 list_for_each_entry(p, &tty_drivers, tty_drivers) {
412 if (!len || strncmp(name, p->name, len) != 0)
420 if (tty_line >= 0 && tty_line < p->num && p->ops &&
421 p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) {
422 res = tty_driver_kref_get(p);
427 mutex_unlock(&tty_mutex);
431 EXPORT_SYMBOL_GPL(tty_find_polling_driver);
434 static ssize_t hung_up_tty_read(struct file *file, char __user *buf,
435 size_t count, loff_t *ppos)
440 static ssize_t hung_up_tty_write(struct file *file, const char __user *buf,
441 size_t count, loff_t *ppos)
446 /* No kernel lock held - none needed ;) */
447 static __poll_t hung_up_tty_poll(struct file *filp, poll_table *wait)
449 return EPOLLIN | EPOLLOUT | EPOLLERR | EPOLLHUP | EPOLLRDNORM | EPOLLWRNORM;
452 static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
455 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
458 static long hung_up_tty_compat_ioctl(struct file *file,
459 unsigned int cmd, unsigned long arg)
461 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
464 static int hung_up_tty_fasync(int fd, struct file *file, int on)
469 static void tty_show_fdinfo(struct seq_file *m, struct file *file)
471 struct tty_struct *tty = file_tty(file);
473 if (tty && tty->ops && tty->ops->show_fdinfo)
474 tty->ops->show_fdinfo(tty, m);
477 static const struct file_operations tty_fops = {
482 .unlocked_ioctl = tty_ioctl,
483 .compat_ioctl = tty_compat_ioctl,
485 .release = tty_release,
486 .fasync = tty_fasync,
487 .show_fdinfo = tty_show_fdinfo,
490 static const struct file_operations console_fops = {
493 .write = redirected_tty_write,
495 .unlocked_ioctl = tty_ioctl,
496 .compat_ioctl = tty_compat_ioctl,
498 .release = tty_release,
499 .fasync = tty_fasync,
502 static const struct file_operations hung_up_tty_fops = {
504 .read = hung_up_tty_read,
505 .write = hung_up_tty_write,
506 .poll = hung_up_tty_poll,
507 .unlocked_ioctl = hung_up_tty_ioctl,
508 .compat_ioctl = hung_up_tty_compat_ioctl,
509 .release = tty_release,
510 .fasync = hung_up_tty_fasync,
513 static DEFINE_SPINLOCK(redirect_lock);
514 static struct file *redirect;
517 * tty_wakeup - request more data
520 * Internal and external helper for wakeups of tty. This function
521 * informs the line discipline if present that the driver is ready
522 * to receive more output data.
525 void tty_wakeup(struct tty_struct *tty)
527 struct tty_ldisc *ld;
529 if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
530 ld = tty_ldisc_ref(tty);
532 if (ld->ops->write_wakeup)
533 ld->ops->write_wakeup(tty);
537 wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
540 EXPORT_SYMBOL_GPL(tty_wakeup);
543 * __tty_hangup - actual handler for hangup events
546 * This can be called by a "kworker" kernel thread. That is process
547 * synchronous but doesn't hold any locks, so we need to make sure we
548 * have the appropriate locks for what we're doing.
550 * The hangup event clears any pending redirections onto the hung up
551 * device. It ensures future writes will error and it does the needed
552 * line discipline hangup and signal delivery. The tty object itself
557 * redirect lock for undoing redirection
558 * file list lock for manipulating list of ttys
559 * tty_ldiscs_lock from called functions
560 * termios_rwsem resetting termios data
561 * tasklist_lock to walk task list for hangup event
562 * ->siglock to protect ->signal/->sighand
564 static void __tty_hangup(struct tty_struct *tty, int exit_session)
566 struct file *cons_filp = NULL;
567 struct file *filp, *f = NULL;
568 struct tty_file_private *priv;
569 int closecount = 0, n;
576 spin_lock(&redirect_lock);
577 if (redirect && file_tty(redirect) == tty) {
581 spin_unlock(&redirect_lock);
585 if (test_bit(TTY_HUPPED, &tty->flags)) {
591 * Some console devices aren't actually hung up for technical and
592 * historical reasons, which can lead to indefinite interruptible
593 * sleep in n_tty_read(). The following explicitly tells
594 * n_tty_read() to abort readers.
596 set_bit(TTY_HUPPING, &tty->flags);
598 /* inuse_filps is protected by the single tty lock,
599 this really needs to change if we want to flush the
600 workqueue with the lock held */
601 check_tty_count(tty, "tty_hangup");
603 spin_lock(&tty->files_lock);
604 /* This breaks for file handles being sent over AF_UNIX sockets ? */
605 list_for_each_entry(priv, &tty->tty_files, list) {
607 if (filp->f_op->write == redirected_tty_write)
609 if (filp->f_op->write != tty_write)
612 __tty_fasync(-1, filp, 0); /* can't block */
613 filp->f_op = &hung_up_tty_fops;
615 spin_unlock(&tty->files_lock);
617 refs = tty_signal_session_leader(tty, exit_session);
618 /* Account for the p->signal references we killed */
622 tty_ldisc_hangup(tty, cons_filp != NULL);
624 spin_lock_irq(&tty->ctrl_lock);
625 clear_bit(TTY_THROTTLED, &tty->flags);
626 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
627 put_pid(tty->session);
631 tty->ctrl_status = 0;
632 spin_unlock_irq(&tty->ctrl_lock);
635 * If one of the devices matches a console pointer, we
636 * cannot just call hangup() because that will cause
637 * tty->count and state->count to go out of sync.
638 * So we just call close() the right number of times.
642 for (n = 0; n < closecount; n++)
643 tty->ops->close(tty, cons_filp);
644 } else if (tty->ops->hangup)
645 tty->ops->hangup(tty);
647 * We don't want to have driver/ldisc interactions beyond the ones
648 * we did here. The driver layer expects no calls after ->hangup()
649 * from the ldisc side, which is now guaranteed.
651 set_bit(TTY_HUPPED, &tty->flags);
652 clear_bit(TTY_HUPPING, &tty->flags);
659 static void do_tty_hangup(struct work_struct *work)
661 struct tty_struct *tty =
662 container_of(work, struct tty_struct, hangup_work);
664 __tty_hangup(tty, 0);
668 * tty_hangup - trigger a hangup event
669 * @tty: tty to hangup
671 * A carrier loss (virtual or otherwise) has occurred on this like
672 * schedule a hangup sequence to run after this event.
675 void tty_hangup(struct tty_struct *tty)
677 tty_debug_hangup(tty, "hangup\n");
678 schedule_work(&tty->hangup_work);
681 EXPORT_SYMBOL(tty_hangup);
684 * tty_vhangup - process vhangup
685 * @tty: tty to hangup
687 * The user has asked via system call for the terminal to be hung up.
688 * We do this synchronously so that when the syscall returns the process
689 * is complete. That guarantee is necessary for security reasons.
692 void tty_vhangup(struct tty_struct *tty)
694 tty_debug_hangup(tty, "vhangup\n");
695 __tty_hangup(tty, 0);
698 EXPORT_SYMBOL(tty_vhangup);
702 * tty_vhangup_self - process vhangup for own ctty
704 * Perform a vhangup on the current controlling tty
707 void tty_vhangup_self(void)
709 struct tty_struct *tty;
711 tty = get_current_tty();
719 * tty_vhangup_session - hangup session leader exit
720 * @tty: tty to hangup
722 * The session leader is exiting and hanging up its controlling terminal.
723 * Every process in the foreground process group is signalled SIGHUP.
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_session(struct tty_struct *tty)
731 tty_debug_hangup(tty, "session hangup\n");
732 __tty_hangup(tty, 1);
736 * tty_hung_up_p - was tty hung up
737 * @filp: file pointer of tty
739 * Return true if the tty has been subject to a vhangup or a carrier
743 int tty_hung_up_p(struct file *filp)
745 return (filp && filp->f_op == &hung_up_tty_fops);
748 EXPORT_SYMBOL(tty_hung_up_p);
751 * stop_tty - propagate flow control
754 * Perform flow control to the driver. May be called
755 * on an already stopped device and will not re-call the driver
758 * This functionality is used by both the line disciplines for
759 * halting incoming flow and by the driver. It may therefore be
760 * called from any context, may be under the tty atomic_write_lock
767 void __stop_tty(struct tty_struct *tty)
776 void stop_tty(struct tty_struct *tty)
780 spin_lock_irqsave(&tty->flow_lock, flags);
782 spin_unlock_irqrestore(&tty->flow_lock, flags);
784 EXPORT_SYMBOL(stop_tty);
787 * start_tty - propagate flow control
790 * Start a tty that has been stopped if at all possible. If this
791 * tty was previous stopped and is now being started, the driver
792 * start method is invoked and the line discipline woken.
798 void __start_tty(struct tty_struct *tty)
800 if (!tty->stopped || tty->flow_stopped)
804 tty->ops->start(tty);
808 void start_tty(struct tty_struct *tty)
812 spin_lock_irqsave(&tty->flow_lock, flags);
814 spin_unlock_irqrestore(&tty->flow_lock, flags);
816 EXPORT_SYMBOL(start_tty);
818 static void tty_update_time(struct timespec64 *time)
820 time64_t sec = ktime_get_real_seconds();
823 * We only care if the two values differ in anything other than the
824 * lower three bits (i.e every 8 seconds). If so, then we can update
825 * the time of the tty device, otherwise it could be construded as a
826 * security leak to let userspace know the exact timing of the tty.
828 if ((sec ^ time->tv_sec) & ~7)
833 * tty_read - read method for tty device files
834 * @file: pointer to tty file
836 * @count: size of user buffer
839 * Perform the read system call function on this terminal device. Checks
840 * for hung up devices before calling the line discipline method.
843 * Locks the line discipline internally while needed. Multiple
844 * read calls may be outstanding in parallel.
847 static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
851 struct inode *inode = file_inode(file);
852 struct tty_struct *tty = file_tty(file);
853 struct tty_ldisc *ld;
855 if (tty_paranoia_check(tty, inode, "tty_read"))
857 if (!tty || tty_io_error(tty))
860 /* We want to wait for the line discipline to sort out in this
862 ld = tty_ldisc_ref_wait(tty);
864 return hung_up_tty_read(file, buf, count, ppos);
866 i = ld->ops->read(tty, file, buf, count);
872 tty_update_time(&inode->i_atime);
877 static void tty_write_unlock(struct tty_struct *tty)
879 mutex_unlock(&tty->atomic_write_lock);
880 wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
883 static int tty_write_lock(struct tty_struct *tty, int ndelay)
885 if (!mutex_trylock(&tty->atomic_write_lock)) {
888 if (mutex_lock_interruptible(&tty->atomic_write_lock))
895 * Split writes up in sane blocksizes to avoid
896 * denial-of-service type attacks
898 static inline ssize_t do_tty_write(
899 ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
900 struct tty_struct *tty,
902 const char __user *buf,
905 ssize_t ret, written = 0;
908 ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
913 * We chunk up writes into a temporary buffer. This
914 * simplifies low-level drivers immensely, since they
915 * don't have locking issues and user mode accesses.
917 * But if TTY_NO_WRITE_SPLIT is set, we should use a
920 * The default chunk-size is 2kB, because the NTTY
921 * layer has problems with bigger chunks. It will
922 * claim to be able to handle more characters than
925 * FIXME: This can probably go away now except that 64K chunks
926 * are too likely to fail unless switched to vmalloc...
929 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
934 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
935 if (tty->write_cnt < chunk) {
936 unsigned char *buf_chunk;
941 buf_chunk = kmalloc(chunk, GFP_KERNEL);
946 kfree(tty->write_buf);
947 tty->write_cnt = chunk;
948 tty->write_buf = buf_chunk;
951 /* Do the write .. */
957 if (copy_from_user(tty->write_buf, buf, size))
959 ret = write(tty, file, tty->write_buf, size);
968 if (signal_pending(current))
973 tty_update_time(&file_inode(file)->i_mtime);
977 tty_write_unlock(tty);
982 * tty_write_message - write a message to a certain tty, not just the console.
983 * @tty: the destination tty_struct
984 * @msg: the message to write
986 * This is used for messages that need to be redirected to a specific tty.
987 * We don't put it into the syslog queue right now maybe in the future if
990 * We must still hold the BTM and test the CLOSING flag for the moment.
993 void tty_write_message(struct tty_struct *tty, char *msg)
996 mutex_lock(&tty->atomic_write_lock);
998 if (tty->ops->write && tty->count > 0)
999 tty->ops->write(tty, msg, strlen(msg));
1001 tty_write_unlock(tty);
1008 * tty_write - write method for tty device file
1009 * @file: tty file pointer
1010 * @buf: user data to write
1011 * @count: bytes to write
1014 * Write data to a tty device via the line discipline.
1017 * Locks the line discipline as required
1018 * Writes to the tty driver are serialized by the atomic_write_lock
1019 * and are then processed in chunks to the device. The line discipline
1020 * write method will not be invoked in parallel for each device.
1023 static ssize_t tty_write(struct file *file, const char __user *buf,
1024 size_t count, loff_t *ppos)
1026 struct tty_struct *tty = file_tty(file);
1027 struct tty_ldisc *ld;
1030 if (tty_paranoia_check(tty, file_inode(file), "tty_write"))
1032 if (!tty || !tty->ops->write || tty_io_error(tty))
1034 /* Short term debug to catch buggy drivers */
1035 if (tty->ops->write_room == NULL)
1036 tty_err(tty, "missing write_room method\n");
1037 ld = tty_ldisc_ref_wait(tty);
1039 return hung_up_tty_write(file, buf, count, ppos);
1040 if (!ld->ops->write)
1043 ret = do_tty_write(ld->ops->write, tty, file, buf, count);
1044 tty_ldisc_deref(ld);
1048 ssize_t redirected_tty_write(struct file *file, const char __user *buf,
1049 size_t count, loff_t *ppos)
1051 struct file *p = NULL;
1053 spin_lock(&redirect_lock);
1055 p = get_file(redirect);
1056 spin_unlock(&redirect_lock);
1060 res = vfs_write(p, buf, count, &p->f_pos);
1064 return tty_write(file, buf, count, ppos);
1068 * tty_send_xchar - send priority character
1070 * Send a high priority character to the tty even if stopped
1072 * Locking: none for xchar method, write ordering for write method.
1075 int tty_send_xchar(struct tty_struct *tty, char ch)
1077 int was_stopped = tty->stopped;
1079 if (tty->ops->send_xchar) {
1080 down_read(&tty->termios_rwsem);
1081 tty->ops->send_xchar(tty, ch);
1082 up_read(&tty->termios_rwsem);
1086 if (tty_write_lock(tty, 0) < 0)
1087 return -ERESTARTSYS;
1089 down_read(&tty->termios_rwsem);
1092 tty->ops->write(tty, &ch, 1);
1095 up_read(&tty->termios_rwsem);
1096 tty_write_unlock(tty);
1100 static char ptychar[] = "pqrstuvwxyzabcde";
1103 * pty_line_name - generate name for a pty
1104 * @driver: the tty driver in use
1105 * @index: the minor number
1106 * @p: output buffer of at least 6 bytes
1108 * Generate a name from a driver reference and write it to the output
1113 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1115 int i = index + driver->name_base;
1116 /* ->name is initialized to "ttyp", but "tty" is expected */
1117 sprintf(p, "%s%c%x",
1118 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1119 ptychar[i >> 4 & 0xf], i & 0xf);
1123 * tty_line_name - generate name for a tty
1124 * @driver: the tty driver in use
1125 * @index: the minor number
1126 * @p: output buffer of at least 7 bytes
1128 * Generate a name from a driver reference and write it to the output
1133 static ssize_t tty_line_name(struct tty_driver *driver, int index, char *p)
1135 if (driver->flags & TTY_DRIVER_UNNUMBERED_NODE)
1136 return sprintf(p, "%s", driver->name);
1138 return sprintf(p, "%s%d", driver->name,
1139 index + driver->name_base);
1143 * tty_driver_lookup_tty() - find an existing tty, if any
1144 * @driver: the driver for the tty
1145 * @idx: the minor number
1147 * Return the tty, if found. If not found, return NULL or ERR_PTR() if the
1148 * driver lookup() method returns an error.
1150 * Locking: tty_mutex must be held. If the tty is found, bump the tty kref.
1152 static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
1153 struct file *file, int idx)
1155 struct tty_struct *tty;
1157 if (driver->ops->lookup)
1159 tty = ERR_PTR(-EIO);
1161 tty = driver->ops->lookup(driver, file, idx);
1163 tty = driver->ttys[idx];
1171 * tty_init_termios - helper for termios setup
1172 * @tty: the tty to set up
1174 * Initialise the termios structures for this tty. Thus runs under
1175 * the tty_mutex currently so we can be relaxed about ordering.
1178 void tty_init_termios(struct tty_struct *tty)
1180 struct ktermios *tp;
1181 int idx = tty->index;
1183 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1184 tty->termios = tty->driver->init_termios;
1186 /* Check for lazy saved data */
1187 tp = tty->driver->termios[idx];
1190 tty->termios.c_line = tty->driver->init_termios.c_line;
1192 tty->termios = tty->driver->init_termios;
1194 /* Compatibility until drivers always set this */
1195 tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
1196 tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
1198 EXPORT_SYMBOL_GPL(tty_init_termios);
1200 int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty)
1202 tty_init_termios(tty);
1203 tty_driver_kref_get(driver);
1205 driver->ttys[tty->index] = tty;
1208 EXPORT_SYMBOL_GPL(tty_standard_install);
1211 * tty_driver_install_tty() - install a tty entry in the driver
1212 * @driver: the driver for the tty
1215 * Install a tty object into the driver tables. The tty->index field
1216 * will be set by the time this is called. This method is responsible
1217 * for ensuring any need additional structures are allocated and
1220 * Locking: tty_mutex for now
1222 static int tty_driver_install_tty(struct tty_driver *driver,
1223 struct tty_struct *tty)
1225 return driver->ops->install ? driver->ops->install(driver, tty) :
1226 tty_standard_install(driver, tty);
1230 * tty_driver_remove_tty() - remove a tty from the driver tables
1231 * @driver: the driver for the tty
1232 * @idx: the minor number
1234 * Remvoe a tty object from the driver tables. The tty->index field
1235 * will be set by the time this is called.
1237 * Locking: tty_mutex for now
1239 static void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *tty)
1241 if (driver->ops->remove)
1242 driver->ops->remove(driver, tty);
1244 driver->ttys[tty->index] = NULL;
1248 * tty_reopen() - fast re-open of an open tty
1249 * @tty - the tty to open
1251 * Return 0 on success, -errno on error.
1252 * Re-opens on master ptys are not allowed and return -EIO.
1254 * Locking: Caller must hold tty_lock
1256 static int tty_reopen(struct tty_struct *tty)
1258 struct tty_driver *driver = tty->driver;
1259 struct tty_ldisc *ld;
1262 if (driver->type == TTY_DRIVER_TYPE_PTY &&
1263 driver->subtype == PTY_TYPE_MASTER)
1269 if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
1272 ld = tty_ldisc_ref_wait(tty);
1274 tty_ldisc_deref(ld);
1276 retval = tty_ldisc_lock(tty, 5 * HZ);
1281 retval = tty_ldisc_reinit(tty, tty->termios.c_line);
1282 tty_ldisc_unlock(tty);
1292 * tty_init_dev - initialise a tty device
1293 * @driver: tty driver we are opening a device on
1294 * @idx: device index
1295 * @ret_tty: returned tty structure
1297 * Prepare a tty device. This may not be a "new" clean device but
1298 * could also be an active device. The pty drivers require special
1299 * handling because of this.
1302 * The function is called under the tty_mutex, which
1303 * protects us from the tty struct or driver itself going away.
1305 * On exit the tty device has the line discipline attached and
1306 * a reference count of 1. If a pair was created for pty/tty use
1307 * and the other was a pty master then it too has a reference count of 1.
1309 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1310 * failed open. The new code protects the open with a mutex, so it's
1311 * really quite straightforward. The mutex locking can probably be
1312 * relaxed for the (most common) case of reopening a tty.
1315 struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
1317 struct tty_struct *tty;
1321 * First time open is complex, especially for PTY devices.
1322 * This code guarantees that either everything succeeds and the
1323 * TTY is ready for operation, or else the table slots are vacated
1324 * and the allocated memory released. (Except that the termios
1328 if (!try_module_get(driver->owner))
1329 return ERR_PTR(-ENODEV);
1331 tty = alloc_tty_struct(driver, idx);
1334 goto err_module_put;
1338 retval = tty_driver_install_tty(driver, tty);
1343 tty->port = driver->ports[idx];
1345 WARN_RATELIMIT(!tty->port,
1346 "%s: %s driver does not set tty->port. This will crash the kernel later. Fix the driver!\n",
1347 __func__, tty->driver->name);
1349 retval = tty_ldisc_lock(tty, 5 * HZ);
1351 goto err_release_lock;
1352 tty->port->itty = tty;
1355 * Structures all installed ... call the ldisc open routines.
1356 * If we fail here just call release_tty to clean up. No need
1357 * to decrement the use counts, as release_tty doesn't care.
1359 retval = tty_ldisc_setup(tty, tty->link);
1361 goto err_release_tty;
1362 tty_ldisc_unlock(tty);
1363 /* Return the tty locked so that it cannot vanish under the caller */
1368 free_tty_struct(tty);
1370 module_put(driver->owner);
1371 return ERR_PTR(retval);
1373 /* call the tty release_tty routine to clean out this slot */
1375 tty_ldisc_unlock(tty);
1376 tty_info_ratelimited(tty, "ldisc open failed (%d), clearing slot %d\n",
1380 release_tty(tty, idx);
1381 return ERR_PTR(retval);
1385 * tty_save_termios() - save tty termios data in driver table
1386 * @tty: tty whose termios data to save
1388 * Locking: Caller guarantees serialisation with tty_init_termios().
1390 void tty_save_termios(struct tty_struct *tty)
1392 struct ktermios *tp;
1393 int idx = tty->index;
1395 /* If the port is going to reset then it has no termios to save */
1396 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1399 /* Stash the termios data */
1400 tp = tty->driver->termios[idx];
1402 tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
1405 tty->driver->termios[idx] = tp;
1409 EXPORT_SYMBOL_GPL(tty_save_termios);
1412 * tty_flush_works - flush all works of a tty/pty pair
1413 * @tty: tty device to flush works for (or either end of a pty pair)
1415 * Sync flush all works belonging to @tty (and the 'other' tty).
1417 static void tty_flush_works(struct tty_struct *tty)
1419 flush_work(&tty->SAK_work);
1420 flush_work(&tty->hangup_work);
1422 flush_work(&tty->link->SAK_work);
1423 flush_work(&tty->link->hangup_work);
1428 * release_one_tty - release tty structure memory
1429 * @kref: kref of tty we are obliterating
1431 * Releases memory associated with a tty structure, and clears out the
1432 * driver table slots. This function is called when a device is no longer
1433 * in use. It also gets called when setup of a device fails.
1436 * takes the file list lock internally when working on the list
1437 * of ttys that the driver keeps.
1439 * This method gets called from a work queue so that the driver private
1440 * cleanup ops can sleep (needed for USB at least)
1442 static void release_one_tty(struct work_struct *work)
1444 struct tty_struct *tty =
1445 container_of(work, struct tty_struct, hangup_work);
1446 struct tty_driver *driver = tty->driver;
1447 struct module *owner = driver->owner;
1449 if (tty->ops->cleanup)
1450 tty->ops->cleanup(tty);
1453 tty_driver_kref_put(driver);
1456 spin_lock(&tty->files_lock);
1457 list_del_init(&tty->tty_files);
1458 spin_unlock(&tty->files_lock);
1461 put_pid(tty->session);
1462 free_tty_struct(tty);
1465 static void queue_release_one_tty(struct kref *kref)
1467 struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1469 /* The hangup queue is now free so we can reuse it rather than
1470 waste a chunk of memory for each port */
1471 INIT_WORK(&tty->hangup_work, release_one_tty);
1472 schedule_work(&tty->hangup_work);
1476 * tty_kref_put - release a tty kref
1479 * Release a reference to a tty device and if need be let the kref
1480 * layer destruct the object for us
1483 void tty_kref_put(struct tty_struct *tty)
1486 kref_put(&tty->kref, queue_release_one_tty);
1488 EXPORT_SYMBOL(tty_kref_put);
1491 * release_tty - release tty structure memory
1493 * Release both @tty and a possible linked partner (think pty pair),
1494 * and decrement the refcount of the backing module.
1498 * takes the file list lock internally when working on the list
1499 * of ttys that the driver keeps.
1502 static void release_tty(struct tty_struct *tty, int idx)
1504 /* This should always be true but check for the moment */
1505 WARN_ON(tty->index != idx);
1506 WARN_ON(!mutex_is_locked(&tty_mutex));
1507 if (tty->ops->shutdown)
1508 tty->ops->shutdown(tty);
1509 tty_save_termios(tty);
1510 tty_driver_remove_tty(tty->driver, tty);
1511 tty->port->itty = NULL;
1513 tty->link->port->itty = NULL;
1514 tty_buffer_cancel_work(tty->port);
1516 tty_buffer_cancel_work(tty->link->port);
1518 tty_kref_put(tty->link);
1523 * tty_release_checks - check a tty before real release
1524 * @tty: tty to check
1525 * @o_tty: link of @tty (if any)
1526 * @idx: index of the tty
1528 * Performs some paranoid checking before true release of the @tty.
1529 * This is a no-op unless TTY_PARANOIA_CHECK is defined.
1531 static int tty_release_checks(struct tty_struct *tty, int idx)
1533 #ifdef TTY_PARANOIA_CHECK
1534 if (idx < 0 || idx >= tty->driver->num) {
1535 tty_debug(tty, "bad idx %d\n", idx);
1539 /* not much to check for devpts */
1540 if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)
1543 if (tty != tty->driver->ttys[idx]) {
1544 tty_debug(tty, "bad driver table[%d] = %p\n",
1545 idx, tty->driver->ttys[idx]);
1548 if (tty->driver->other) {
1549 struct tty_struct *o_tty = tty->link;
1551 if (o_tty != tty->driver->other->ttys[idx]) {
1552 tty_debug(tty, "bad other table[%d] = %p\n",
1553 idx, tty->driver->other->ttys[idx]);
1556 if (o_tty->link != tty) {
1557 tty_debug(tty, "bad link = %p\n", o_tty->link);
1566 * tty_kclose - closes tty opened by tty_kopen
1569 * Performs the final steps to release and free a tty device. It is the
1570 * same as tty_release_struct except that it also resets TTY_PORT_KOPENED
1571 * flag on tty->port.
1573 void tty_kclose(struct tty_struct *tty)
1576 * Ask the line discipline code to release its structures
1578 tty_ldisc_release(tty);
1580 /* Wait for pending work before tty destruction commmences */
1581 tty_flush_works(tty);
1583 tty_debug_hangup(tty, "freeing structure\n");
1585 * The release_tty function takes care of the details of clearing
1586 * the slots and preserving the termios structure. The tty_unlock_pair
1587 * should be safe as we keep a kref while the tty is locked (so the
1588 * unlock never unlocks a freed tty).
1590 mutex_lock(&tty_mutex);
1591 tty_port_set_kopened(tty->port, 0);
1592 release_tty(tty, tty->index);
1593 mutex_unlock(&tty_mutex);
1595 EXPORT_SYMBOL_GPL(tty_kclose);
1598 * tty_release_struct - release a tty struct
1600 * @idx: index of the tty
1602 * Performs the final steps to release and free a tty device. It is
1603 * roughly the reverse of tty_init_dev.
1605 void tty_release_struct(struct tty_struct *tty, int idx)
1608 * Ask the line discipline code to release its structures
1610 tty_ldisc_release(tty);
1612 /* Wait for pending work before tty destruction commmences */
1613 tty_flush_works(tty);
1615 tty_debug_hangup(tty, "freeing structure\n");
1617 * The release_tty function takes care of the details of clearing
1618 * the slots and preserving the termios structure. The tty_unlock_pair
1619 * should be safe as we keep a kref while the tty is locked (so the
1620 * unlock never unlocks a freed tty).
1622 mutex_lock(&tty_mutex);
1623 release_tty(tty, idx);
1624 mutex_unlock(&tty_mutex);
1626 EXPORT_SYMBOL_GPL(tty_release_struct);
1629 * tty_release - vfs callback for close
1630 * @inode: inode of tty
1631 * @filp: file pointer for handle to tty
1633 * Called the last time each file handle is closed that references
1634 * this tty. There may however be several such references.
1637 * Takes bkl. See tty_release_dev
1639 * Even releasing the tty structures is a tricky business.. We have
1640 * to be very careful that the structures are all released at the
1641 * same time, as interrupts might otherwise get the wrong pointers.
1643 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1644 * lead to double frees or releasing memory still in use.
1647 int tty_release(struct inode *inode, struct file *filp)
1649 struct tty_struct *tty = file_tty(filp);
1650 struct tty_struct *o_tty = NULL;
1651 int do_sleep, final;
1656 if (tty_paranoia_check(tty, inode, __func__))
1660 check_tty_count(tty, __func__);
1662 __tty_fasync(-1, filp, 0);
1665 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1666 tty->driver->subtype == PTY_TYPE_MASTER)
1669 if (tty_release_checks(tty, idx)) {
1674 tty_debug_hangup(tty, "releasing (count=%d)\n", tty->count);
1676 if (tty->ops->close)
1677 tty->ops->close(tty, filp);
1679 /* If tty is pty master, lock the slave pty (stable lock order) */
1680 tty_lock_slave(o_tty);
1683 * Sanity check: if tty->count is going to zero, there shouldn't be
1684 * any waiters on tty->read_wait or tty->write_wait. We test the
1685 * wait queues and kick everyone out _before_ actually starting to
1686 * close. This ensures that we won't block while releasing the tty
1689 * The test for the o_tty closing is necessary, since the master and
1690 * slave sides may close in any order. If the slave side closes out
1691 * first, its count will be one, since the master side holds an open.
1692 * Thus this test wouldn't be triggered at the time the slave closed,
1698 if (tty->count <= 1) {
1699 if (waitqueue_active(&tty->read_wait)) {
1700 wake_up_poll(&tty->read_wait, EPOLLIN);
1703 if (waitqueue_active(&tty->write_wait)) {
1704 wake_up_poll(&tty->write_wait, EPOLLOUT);
1708 if (o_tty && o_tty->count <= 1) {
1709 if (waitqueue_active(&o_tty->read_wait)) {
1710 wake_up_poll(&o_tty->read_wait, EPOLLIN);
1713 if (waitqueue_active(&o_tty->write_wait)) {
1714 wake_up_poll(&o_tty->write_wait, EPOLLOUT);
1723 tty_warn(tty, "read/write wait queue active!\n");
1725 schedule_timeout_killable(timeout);
1726 if (timeout < 120 * HZ)
1727 timeout = 2 * timeout + 1;
1729 timeout = MAX_SCHEDULE_TIMEOUT;
1733 if (--o_tty->count < 0) {
1734 tty_warn(tty, "bad slave count (%d)\n", o_tty->count);
1738 if (--tty->count < 0) {
1739 tty_warn(tty, "bad tty->count (%d)\n", tty->count);
1744 * We've decremented tty->count, so we need to remove this file
1745 * descriptor off the tty->tty_files list; this serves two
1747 * - check_tty_count sees the correct number of file descriptors
1748 * associated with this tty.
1749 * - do_tty_hangup no longer sees this file descriptor as
1750 * something that needs to be handled for hangups.
1755 * Perform some housekeeping before deciding whether to return.
1757 * If _either_ side is closing, make sure there aren't any
1758 * processes that still think tty or o_tty is their controlling
1762 read_lock(&tasklist_lock);
1763 session_clear_tty(tty->session);
1765 session_clear_tty(o_tty->session);
1766 read_unlock(&tasklist_lock);
1769 /* check whether both sides are closing ... */
1770 final = !tty->count && !(o_tty && o_tty->count);
1772 tty_unlock_slave(o_tty);
1775 /* At this point, the tty->count == 0 should ensure a dead tty
1776 cannot be re-opened by a racing opener */
1781 tty_debug_hangup(tty, "final close\n");
1783 tty_release_struct(tty, idx);
1788 * tty_open_current_tty - get locked tty of current task
1789 * @device: device number
1790 * @filp: file pointer to tty
1791 * @return: locked tty of the current task iff @device is /dev/tty
1793 * Performs a re-open of the current task's controlling tty.
1795 * We cannot return driver and index like for the other nodes because
1796 * devpts will not work then. It expects inodes to be from devpts FS.
1798 static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
1800 struct tty_struct *tty;
1803 if (device != MKDEV(TTYAUX_MAJOR, 0))
1806 tty = get_current_tty();
1808 return ERR_PTR(-ENXIO);
1810 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1813 tty_kref_put(tty); /* safe to drop the kref now */
1815 retval = tty_reopen(tty);
1818 tty = ERR_PTR(retval);
1824 * tty_lookup_driver - lookup a tty driver for a given device file
1825 * @device: device number
1826 * @filp: file pointer to tty
1827 * @index: index for the device in the @return driver
1828 * @return: driver for this inode (with increased refcount)
1830 * If @return is not erroneous, the caller is responsible to decrement the
1831 * refcount by tty_driver_kref_put.
1833 * Locking: tty_mutex protects get_tty_driver
1835 static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
1838 struct tty_driver *driver;
1842 case MKDEV(TTY_MAJOR, 0): {
1843 extern struct tty_driver *console_driver;
1844 driver = tty_driver_kref_get(console_driver);
1845 *index = fg_console;
1849 case MKDEV(TTYAUX_MAJOR, 1): {
1850 struct tty_driver *console_driver = console_device(index);
1851 if (console_driver) {
1852 driver = tty_driver_kref_get(console_driver);
1853 if (driver && filp) {
1854 /* Don't let /dev/console block */
1855 filp->f_flags |= O_NONBLOCK;
1859 return ERR_PTR(-ENODEV);
1862 driver = get_tty_driver(device, index);
1864 return ERR_PTR(-ENODEV);
1871 * tty_kopen - open a tty device for kernel
1872 * @device: dev_t of device to open
1874 * Opens tty exclusively for kernel. Performs the driver lookup,
1875 * makes sure it's not already opened and performs the first-time
1876 * tty initialization.
1878 * Returns the locked initialized &tty_struct
1880 * Claims the global tty_mutex to serialize:
1881 * - concurrent first-time tty initialization
1882 * - concurrent tty driver removal w/ lookup
1883 * - concurrent tty removal from driver table
1885 struct tty_struct *tty_kopen(dev_t device)
1887 struct tty_struct *tty;
1888 struct tty_driver *driver = NULL;
1891 mutex_lock(&tty_mutex);
1892 driver = tty_lookup_driver(device, NULL, &index);
1893 if (IS_ERR(driver)) {
1894 mutex_unlock(&tty_mutex);
1895 return ERR_CAST(driver);
1898 /* check whether we're reopening an existing tty */
1899 tty = tty_driver_lookup_tty(driver, NULL, index);
1904 /* drop kref from tty_driver_lookup_tty() */
1906 tty = ERR_PTR(-EBUSY);
1907 } else { /* tty_init_dev returns tty with the tty_lock held */
1908 tty = tty_init_dev(driver, index);
1911 tty_port_set_kopened(tty->port, 1);
1914 mutex_unlock(&tty_mutex);
1915 tty_driver_kref_put(driver);
1918 EXPORT_SYMBOL_GPL(tty_kopen);
1921 * tty_open_by_driver - open a tty device
1922 * @device: dev_t of device to open
1923 * @inode: inode of device file
1924 * @filp: file pointer to tty
1926 * Performs the driver lookup, checks for a reopen, or otherwise
1927 * performs the first-time tty initialization.
1929 * Returns the locked initialized or re-opened &tty_struct
1931 * Claims the global tty_mutex to serialize:
1932 * - concurrent first-time tty initialization
1933 * - concurrent tty driver removal w/ lookup
1934 * - concurrent tty removal from driver table
1936 static struct tty_struct *tty_open_by_driver(dev_t device, struct inode *inode,
1939 struct tty_struct *tty;
1940 struct tty_driver *driver = NULL;
1944 mutex_lock(&tty_mutex);
1945 driver = tty_lookup_driver(device, filp, &index);
1946 if (IS_ERR(driver)) {
1947 mutex_unlock(&tty_mutex);
1948 return ERR_CAST(driver);
1951 /* check whether we're reopening an existing tty */
1952 tty = tty_driver_lookup_tty(driver, filp, index);
1954 mutex_unlock(&tty_mutex);
1959 if (tty_port_kopened(tty->port)) {
1961 mutex_unlock(&tty_mutex);
1962 tty = ERR_PTR(-EBUSY);
1965 mutex_unlock(&tty_mutex);
1966 retval = tty_lock_interruptible(tty);
1967 tty_kref_put(tty); /* drop kref from tty_driver_lookup_tty() */
1969 if (retval == -EINTR)
1970 retval = -ERESTARTSYS;
1971 tty = ERR_PTR(retval);
1974 retval = tty_reopen(tty);
1977 tty = ERR_PTR(retval);
1979 } else { /* Returns with the tty_lock held for now */
1980 tty = tty_init_dev(driver, index);
1981 mutex_unlock(&tty_mutex);
1984 tty_driver_kref_put(driver);
1989 * tty_open - open a tty device
1990 * @inode: inode of device file
1991 * @filp: file pointer to tty
1993 * tty_open and tty_release keep up the tty count that contains the
1994 * number of opens done on a tty. We cannot use the inode-count, as
1995 * different inodes might point to the same tty.
1997 * Open-counting is needed for pty masters, as well as for keeping
1998 * track of serial lines: DTR is dropped when the last close happens.
1999 * (This is not done solely through tty->count, now. - Ted 1/27/92)
2001 * The termios state of a pty is reset on first open so that
2002 * settings don't persist across reuse.
2004 * Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.
2005 * tty->count should protect the rest.
2006 * ->siglock protects ->signal/->sighand
2008 * Note: the tty_unlock/lock cases without a ref are only safe due to
2012 static int tty_open(struct inode *inode, struct file *filp)
2014 struct tty_struct *tty;
2016 dev_t device = inode->i_rdev;
2017 unsigned saved_flags = filp->f_flags;
2019 nonseekable_open(inode, filp);
2022 retval = tty_alloc_file(filp);
2026 tty = tty_open_current_tty(device, filp);
2028 tty = tty_open_by_driver(device, inode, filp);
2031 tty_free_file(filp);
2032 retval = PTR_ERR(tty);
2033 if (retval != -EAGAIN || signal_pending(current))
2039 tty_add_file(tty, filp);
2041 check_tty_count(tty, __func__);
2042 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
2045 retval = tty->ops->open(tty, filp);
2048 filp->f_flags = saved_flags;
2051 tty_debug_hangup(tty, "open error %d, releasing\n", retval);
2053 tty_unlock(tty); /* need to call tty_release without BTM */
2054 tty_release(inode, filp);
2055 if (retval != -ERESTARTSYS)
2058 if (signal_pending(current))
2063 * Need to reset f_op in case a hangup happened.
2065 if (tty_hung_up_p(filp))
2066 filp->f_op = &tty_fops;
2069 clear_bit(TTY_HUPPED, &tty->flags);
2071 noctty = (filp->f_flags & O_NOCTTY) ||
2072 (IS_ENABLED(CONFIG_VT) && device == MKDEV(TTY_MAJOR, 0)) ||
2073 device == MKDEV(TTYAUX_MAJOR, 1) ||
2074 (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2075 tty->driver->subtype == PTY_TYPE_MASTER);
2077 tty_open_proc_set_tty(filp, tty);
2085 * tty_poll - check tty status
2086 * @filp: file being polled
2087 * @wait: poll wait structures to update
2089 * Call the line discipline polling method to obtain the poll
2090 * status of the device.
2092 * Locking: locks called line discipline but ldisc poll method
2093 * may be re-entered freely by other callers.
2096 static __poll_t tty_poll(struct file *filp, poll_table *wait)
2098 struct tty_struct *tty = file_tty(filp);
2099 struct tty_ldisc *ld;
2102 if (tty_paranoia_check(tty, file_inode(filp), "tty_poll"))
2105 ld = tty_ldisc_ref_wait(tty);
2107 return hung_up_tty_poll(filp, wait);
2109 ret = ld->ops->poll(tty, filp, wait);
2110 tty_ldisc_deref(ld);
2114 static int __tty_fasync(int fd, struct file *filp, int on)
2116 struct tty_struct *tty = file_tty(filp);
2117 unsigned long flags;
2120 if (tty_paranoia_check(tty, file_inode(filp), "tty_fasync"))
2123 retval = fasync_helper(fd, filp, on, &tty->fasync);
2131 spin_lock_irqsave(&tty->ctrl_lock, flags);
2134 type = PIDTYPE_PGID;
2136 pid = task_pid(current);
2137 type = PIDTYPE_TGID;
2140 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2141 __f_setown(filp, pid, type, 0);
2149 static int tty_fasync(int fd, struct file *filp, int on)
2151 struct tty_struct *tty = file_tty(filp);
2152 int retval = -ENOTTY;
2155 if (!tty_hung_up_p(filp))
2156 retval = __tty_fasync(fd, filp, on);
2163 * tiocsti - fake input character
2164 * @tty: tty to fake input into
2165 * @p: pointer to character
2167 * Fake input to a tty device. Does the necessary locking and
2170 * FIXME: does not honour flow control ??
2173 * Called functions take tty_ldiscs_lock
2174 * current->signal->tty check is safe without locks
2176 * FIXME: may race normal receive processing
2179 static int tiocsti(struct tty_struct *tty, char __user *p)
2182 struct tty_ldisc *ld;
2184 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2186 if (get_user(ch, p))
2188 tty_audit_tiocsti(tty, ch);
2189 ld = tty_ldisc_ref_wait(tty);
2192 ld->ops->receive_buf(tty, &ch, &mbz, 1);
2193 tty_ldisc_deref(ld);
2198 * tiocgwinsz - implement window query ioctl
2200 * @arg: user buffer for result
2202 * Copies the kernel idea of the window size into the user buffer.
2204 * Locking: tty->winsize_mutex is taken to ensure the winsize data
2208 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2212 mutex_lock(&tty->winsize_mutex);
2213 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2214 mutex_unlock(&tty->winsize_mutex);
2216 return err ? -EFAULT: 0;
2220 * tty_do_resize - resize event
2221 * @tty: tty being resized
2222 * @rows: rows (character)
2223 * @cols: cols (character)
2225 * Update the termios variables and send the necessary signals to
2226 * peform a terminal resize correctly
2229 int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
2234 mutex_lock(&tty->winsize_mutex);
2235 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
2238 /* Signal the foreground process group */
2239 pgrp = tty_get_pgrp(tty);
2241 kill_pgrp(pgrp, SIGWINCH, 1);
2246 mutex_unlock(&tty->winsize_mutex);
2249 EXPORT_SYMBOL(tty_do_resize);
2252 * tiocswinsz - implement window size set ioctl
2253 * @tty; tty side of tty
2254 * @arg: user buffer for result
2256 * Copies the user idea of the window size to the kernel. Traditionally
2257 * this is just advisory information but for the Linux console it
2258 * actually has driver level meaning and triggers a VC resize.
2261 * Driver dependent. The default do_resize method takes the
2262 * tty termios mutex and ctrl_lock. The console takes its own lock
2263 * then calls into the default method.
2266 static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
2268 struct winsize tmp_ws;
2269 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2272 if (tty->ops->resize)
2273 return tty->ops->resize(tty, &tmp_ws);
2275 return tty_do_resize(tty, &tmp_ws);
2279 * tioccons - allow admin to move logical console
2280 * @file: the file to become console
2282 * Allow the administrator to move the redirected console device
2284 * Locking: uses redirect_lock to guard the redirect information
2287 static int tioccons(struct file *file)
2289 if (!capable(CAP_SYS_ADMIN))
2291 if (file->f_op->write == redirected_tty_write) {
2293 spin_lock(&redirect_lock);
2296 spin_unlock(&redirect_lock);
2301 spin_lock(&redirect_lock);
2303 spin_unlock(&redirect_lock);
2306 redirect = get_file(file);
2307 spin_unlock(&redirect_lock);
2312 * tiocsetd - set line discipline
2314 * @p: pointer to user data
2316 * Set the line discipline according to user request.
2318 * Locking: see tty_set_ldisc, this function is just a helper
2321 static int tiocsetd(struct tty_struct *tty, int __user *p)
2326 if (get_user(disc, p))
2329 ret = tty_set_ldisc(tty, disc);
2335 * tiocgetd - get line discipline
2337 * @p: pointer to user data
2339 * Retrieves the line discipline id directly from the ldisc.
2341 * Locking: waits for ldisc reference (in case the line discipline
2342 * is changing or the tty is being hungup)
2345 static int tiocgetd(struct tty_struct *tty, int __user *p)
2347 struct tty_ldisc *ld;
2350 ld = tty_ldisc_ref_wait(tty);
2353 ret = put_user(ld->ops->num, p);
2354 tty_ldisc_deref(ld);
2359 * send_break - performed time break
2360 * @tty: device to break on
2361 * @duration: timeout in mS
2363 * Perform a timed break on hardware that lacks its own driver level
2364 * timed break functionality.
2367 * atomic_write_lock serializes
2371 static int send_break(struct tty_struct *tty, unsigned int duration)
2375 if (tty->ops->break_ctl == NULL)
2378 if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2379 retval = tty->ops->break_ctl(tty, duration);
2381 /* Do the work ourselves */
2382 if (tty_write_lock(tty, 0) < 0)
2384 retval = tty->ops->break_ctl(tty, -1);
2387 if (!signal_pending(current))
2388 msleep_interruptible(duration);
2389 retval = tty->ops->break_ctl(tty, 0);
2391 tty_write_unlock(tty);
2392 if (signal_pending(current))
2399 * tty_tiocmget - get modem status
2401 * @file: user file pointer
2402 * @p: pointer to result
2404 * Obtain the modem status bits from the tty driver if the feature
2405 * is supported. Return -EINVAL if it is not available.
2407 * Locking: none (up to the driver)
2410 static int tty_tiocmget(struct tty_struct *tty, int __user *p)
2412 int retval = -EINVAL;
2414 if (tty->ops->tiocmget) {
2415 retval = tty->ops->tiocmget(tty);
2418 retval = put_user(retval, p);
2424 * tty_tiocmset - set modem status
2426 * @cmd: command - clear bits, set bits or set all
2427 * @p: pointer to desired bits
2429 * Set the modem status bits from the tty driver if the feature
2430 * is supported. Return -EINVAL if it is not available.
2432 * Locking: none (up to the driver)
2435 static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
2439 unsigned int set, clear, val;
2441 if (tty->ops->tiocmset == NULL)
2444 retval = get_user(val, p);
2460 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2461 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2462 return tty->ops->tiocmset(tty, set, clear);
2465 static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
2467 int retval = -EINVAL;
2468 struct serial_icounter_struct icount;
2469 memset(&icount, 0, sizeof(icount));
2470 if (tty->ops->get_icount)
2471 retval = tty->ops->get_icount(tty, &icount);
2474 if (copy_to_user(arg, &icount, sizeof(icount)))
2479 static int tty_tiocsserial(struct tty_struct *tty, struct serial_struct __user *ss)
2481 static DEFINE_RATELIMIT_STATE(depr_flags,
2482 DEFAULT_RATELIMIT_INTERVAL,
2483 DEFAULT_RATELIMIT_BURST);
2484 char comm[TASK_COMM_LEN];
2485 struct serial_struct v;
2488 if (copy_from_user(&v, ss, sizeof(struct serial_struct)))
2491 flags = v.flags & ASYNC_DEPRECATED;
2493 if (flags && __ratelimit(&depr_flags))
2494 pr_warn("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
2495 __func__, get_task_comm(comm, current), flags);
2496 if (!tty->ops->set_serial)
2498 return tty->ops->set_serial(tty, &v);
2501 static int tty_tiocgserial(struct tty_struct *tty, struct serial_struct __user *ss)
2503 struct serial_struct v;
2506 memset(&v, 0, sizeof(struct serial_struct));
2507 if (!tty->ops->get_serial)
2509 err = tty->ops->get_serial(tty, &v);
2510 if (!err && copy_to_user(ss, &v, sizeof(struct serial_struct)))
2516 * if pty, return the slave side (real_tty)
2517 * otherwise, return self
2519 static struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
2521 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2522 tty->driver->subtype == PTY_TYPE_MASTER)
2528 * Split this up, as gcc can choke on it otherwise..
2530 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2532 struct tty_struct *tty = file_tty(file);
2533 struct tty_struct *real_tty;
2534 void __user *p = (void __user *)arg;
2536 struct tty_ldisc *ld;
2538 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2541 real_tty = tty_pair_get_tty(tty);
2544 * Factor out some common prep work
2552 retval = tty_check_change(tty);
2555 if (cmd != TIOCCBRK) {
2556 tty_wait_until_sent(tty, 0);
2557 if (signal_pending(current))
2568 return tiocsti(tty, p);
2570 return tiocgwinsz(real_tty, p);
2572 return tiocswinsz(real_tty, p);
2574 return real_tty != tty ? -EINVAL : tioccons(file);
2576 set_bit(TTY_EXCLUSIVE, &tty->flags);
2579 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2583 int excl = test_bit(TTY_EXCLUSIVE, &tty->flags);
2584 return put_user(excl, (int __user *)p);
2587 return tiocgetd(tty, p);
2589 return tiocsetd(tty, p);
2591 if (!capable(CAP_SYS_ADMIN))
2597 unsigned int ret = new_encode_dev(tty_devnum(real_tty));
2598 return put_user(ret, (unsigned int __user *)p);
2603 case TIOCSBRK: /* Turn break on, unconditionally */
2604 if (tty->ops->break_ctl)
2605 return tty->ops->break_ctl(tty, -1);
2607 case TIOCCBRK: /* Turn break off, unconditionally */
2608 if (tty->ops->break_ctl)
2609 return tty->ops->break_ctl(tty, 0);
2611 case TCSBRK: /* SVID version: non-zero arg --> no break */
2612 /* non-zero arg means wait for all output data
2613 * to be sent (performed above) but don't send break.
2614 * This is used by the tcdrain() termios function.
2617 return send_break(tty, 250);
2619 case TCSBRKP: /* support for POSIX tcsendbreak() */
2620 return send_break(tty, arg ? arg*100 : 250);
2623 return tty_tiocmget(tty, p);
2627 return tty_tiocmset(tty, cmd, p);
2629 return tty_tiocgicount(tty, p);
2634 /* flush tty buffer and allow ldisc to process ioctl */
2635 tty_buffer_flush(tty, NULL);
2640 return tty_tiocsserial(tty, p);
2642 return tty_tiocgserial(tty, p);
2644 /* Special because the struct file is needed */
2645 return ptm_open_peer(file, tty, (int)arg);
2647 retval = tty_jobctrl_ioctl(tty, real_tty, file, cmd, arg);
2648 if (retval != -ENOIOCTLCMD)
2651 if (tty->ops->ioctl) {
2652 retval = tty->ops->ioctl(tty, cmd, arg);
2653 if (retval != -ENOIOCTLCMD)
2656 ld = tty_ldisc_ref_wait(tty);
2658 return hung_up_tty_ioctl(file, cmd, arg);
2660 if (ld->ops->ioctl) {
2661 retval = ld->ops->ioctl(tty, file, cmd, arg);
2662 if (retval == -ENOIOCTLCMD)
2665 tty_ldisc_deref(ld);
2669 #ifdef CONFIG_COMPAT
2671 struct serial_struct32 {
2677 compat_int_t xmit_fifo_size;
2678 compat_int_t custom_divisor;
2679 compat_int_t baud_base;
2680 unsigned short close_delay;
2682 char reserved_char[1];
2684 unsigned short closing_wait; /* time to wait before closing */
2685 unsigned short closing_wait2; /* no longer used... */
2686 compat_uint_t iomem_base;
2687 unsigned short iomem_reg_shift;
2688 unsigned int port_high;
2689 /* compat_ulong_t iomap_base FIXME */
2690 compat_int_t reserved[1];
2693 static int compat_tty_tiocsserial(struct tty_struct *tty,
2694 struct serial_struct32 __user *ss)
2696 static DEFINE_RATELIMIT_STATE(depr_flags,
2697 DEFAULT_RATELIMIT_INTERVAL,
2698 DEFAULT_RATELIMIT_BURST);
2699 char comm[TASK_COMM_LEN];
2700 struct serial_struct32 v32;
2701 struct serial_struct v;
2704 if (copy_from_user(&v32, ss, sizeof(struct serial_struct32)))
2707 memcpy(&v, &v32, offsetof(struct serial_struct32, iomem_base));
2708 v.iomem_base = compat_ptr(v32.iomem_base);
2709 v.iomem_reg_shift = v32.iomem_reg_shift;
2710 v.port_high = v32.port_high;
2713 flags = v.flags & ASYNC_DEPRECATED;
2715 if (flags && __ratelimit(&depr_flags))
2716 pr_warn("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
2717 __func__, get_task_comm(comm, current), flags);
2718 if (!tty->ops->set_serial)
2720 return tty->ops->set_serial(tty, &v);
2723 static int compat_tty_tiocgserial(struct tty_struct *tty,
2724 struct serial_struct32 __user *ss)
2726 struct serial_struct32 v32;
2727 struct serial_struct v;
2729 memset(&v, 0, sizeof(struct serial_struct));
2731 if (!tty->ops->set_serial)
2733 err = tty->ops->get_serial(tty, &v);
2735 memcpy(&v32, &v, offsetof(struct serial_struct32, iomem_base));
2736 v32.iomem_base = (unsigned long)v.iomem_base >> 32 ?
2737 0xfffffff : ptr_to_compat(v.iomem_base);
2738 v32.iomem_reg_shift = v.iomem_reg_shift;
2739 v32.port_high = v.port_high;
2740 if (copy_to_user(ss, &v32, sizeof(struct serial_struct32)))
2745 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2748 struct tty_struct *tty = file_tty(file);
2749 struct tty_ldisc *ld;
2750 int retval = -ENOIOCTLCMD;
2798 case TIOCGLCKTRMIOS:
2799 case TIOCSLCKTRMIOS:
2808 return tty_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
2824 return tty_ioctl(file, cmd, arg);
2827 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2832 return compat_tty_tiocsserial(tty, compat_ptr(arg));
2834 return compat_tty_tiocgserial(tty, compat_ptr(arg));
2836 if (tty->ops->compat_ioctl) {
2837 retval = tty->ops->compat_ioctl(tty, cmd, arg);
2838 if (retval != -ENOIOCTLCMD)
2842 ld = tty_ldisc_ref_wait(tty);
2844 return hung_up_tty_compat_ioctl(file, cmd, arg);
2845 if (ld->ops->compat_ioctl)
2846 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
2847 if (retval == -ENOIOCTLCMD && ld->ops->ioctl)
2848 retval = ld->ops->ioctl(tty, file,
2849 (unsigned long)compat_ptr(cmd), arg);
2850 tty_ldisc_deref(ld);
2856 static int this_tty(const void *t, struct file *file, unsigned fd)
2858 if (likely(file->f_op->read != tty_read))
2860 return file_tty(file) != t ? 0 : fd + 1;
2864 * This implements the "Secure Attention Key" --- the idea is to
2865 * prevent trojan horses by killing all processes associated with this
2866 * tty when the user hits the "Secure Attention Key". Required for
2867 * super-paranoid applications --- see the Orange Book for more details.
2869 * This code could be nicer; ideally it should send a HUP, wait a few
2870 * seconds, then send a INT, and then a KILL signal. But you then
2871 * have to coordinate with the init process, since all processes associated
2872 * with the current tty must be dead before the new getty is allowed
2875 * Now, if it would be correct ;-/ The current code has a nasty hole -
2876 * it doesn't catch files in flight. We may send the descriptor to ourselves
2877 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
2879 * Nasty bug: do_SAK is being called in interrupt context. This can
2880 * deadlock. We punt it up to process context. AKPM - 16Mar2001
2882 void __do_SAK(struct tty_struct *tty)
2887 struct task_struct *g, *p;
2888 struct pid *session;
2893 session = tty->session;
2895 tty_ldisc_flush(tty);
2897 tty_driver_flush_buffer(tty);
2899 read_lock(&tasklist_lock);
2900 /* Kill the entire session */
2901 do_each_pid_task(session, PIDTYPE_SID, p) {
2902 tty_notice(tty, "SAK: killed process %d (%s): by session\n",
2903 task_pid_nr(p), p->comm);
2904 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
2905 } while_each_pid_task(session, PIDTYPE_SID, p);
2907 /* Now kill any processes that happen to have the tty open */
2908 do_each_thread(g, p) {
2909 if (p->signal->tty == tty) {
2910 tty_notice(tty, "SAK: killed process %d (%s): by controlling tty\n",
2911 task_pid_nr(p), p->comm);
2912 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
2916 i = iterate_fd(p->files, 0, this_tty, tty);
2918 tty_notice(tty, "SAK: killed process %d (%s): by fd#%d\n",
2919 task_pid_nr(p), p->comm, i - 1);
2920 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
2923 } while_each_thread(g, p);
2924 read_unlock(&tasklist_lock);
2928 static void do_SAK_work(struct work_struct *work)
2930 struct tty_struct *tty =
2931 container_of(work, struct tty_struct, SAK_work);
2936 * The tq handling here is a little racy - tty->SAK_work may already be queued.
2937 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
2938 * the values which we write to it will be identical to the values which it
2939 * already has. --akpm
2941 void do_SAK(struct tty_struct *tty)
2945 schedule_work(&tty->SAK_work);
2948 EXPORT_SYMBOL(do_SAK);
2950 static int dev_match_devt(struct device *dev, const void *data)
2952 const dev_t *devt = data;
2953 return dev->devt == *devt;
2956 /* Must put_device() after it's unused! */
2957 static struct device *tty_get_device(struct tty_struct *tty)
2959 dev_t devt = tty_devnum(tty);
2960 return class_find_device(tty_class, NULL, &devt, dev_match_devt);
2967 * This subroutine allocates and initializes a tty structure.
2969 * Locking: none - tty in question is not exposed at this point
2972 struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
2974 struct tty_struct *tty;
2976 tty = kzalloc(sizeof(*tty), GFP_KERNEL);
2980 kref_init(&tty->kref);
2981 tty->magic = TTY_MAGIC;
2982 if (tty_ldisc_init(tty)) {
2986 tty->session = NULL;
2988 mutex_init(&tty->legacy_mutex);
2989 mutex_init(&tty->throttle_mutex);
2990 init_rwsem(&tty->termios_rwsem);
2991 mutex_init(&tty->winsize_mutex);
2992 init_ldsem(&tty->ldisc_sem);
2993 init_waitqueue_head(&tty->write_wait);
2994 init_waitqueue_head(&tty->read_wait);
2995 INIT_WORK(&tty->hangup_work, do_tty_hangup);
2996 mutex_init(&tty->atomic_write_lock);
2997 spin_lock_init(&tty->ctrl_lock);
2998 spin_lock_init(&tty->flow_lock);
2999 spin_lock_init(&tty->files_lock);
3000 INIT_LIST_HEAD(&tty->tty_files);
3001 INIT_WORK(&tty->SAK_work, do_SAK_work);
3003 tty->driver = driver;
3004 tty->ops = driver->ops;
3006 tty_line_name(driver, idx, tty->name);
3007 tty->dev = tty_get_device(tty);
3013 * tty_put_char - write one character to a tty
3017 * Write one byte to the tty using the provided put_char method
3018 * if present. Returns the number of characters successfully output.
3020 * Note: the specific put_char operation in the driver layer may go
3021 * away soon. Don't call it directly, use this method
3024 int tty_put_char(struct tty_struct *tty, unsigned char ch)
3026 if (tty->ops->put_char)
3027 return tty->ops->put_char(tty, ch);
3028 return tty->ops->write(tty, &ch, 1);
3030 EXPORT_SYMBOL_GPL(tty_put_char);
3032 struct class *tty_class;
3034 static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
3035 unsigned int index, unsigned int count)
3039 /* init here, since reused cdevs cause crashes */
3040 driver->cdevs[index] = cdev_alloc();
3041 if (!driver->cdevs[index])
3043 driver->cdevs[index]->ops = &tty_fops;
3044 driver->cdevs[index]->owner = driver->owner;
3045 err = cdev_add(driver->cdevs[index], dev, count);
3047 kobject_put(&driver->cdevs[index]->kobj);
3052 * tty_register_device - register a tty device
3053 * @driver: the tty driver that describes the tty device
3054 * @index: the index in the tty driver for this tty device
3055 * @device: a struct device that is associated with this tty device.
3056 * This field is optional, if there is no known struct device
3057 * for this tty device it can be set to NULL safely.
3059 * Returns a pointer to the struct device for this tty device
3060 * (or ERR_PTR(-EFOO) on error).
3062 * This call is required to be made to register an individual tty device
3063 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3064 * that bit is not set, this function should not be called by a tty
3070 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
3071 struct device *device)
3073 return tty_register_device_attr(driver, index, device, NULL, NULL);
3075 EXPORT_SYMBOL(tty_register_device);
3077 static void tty_device_create_release(struct device *dev)
3079 dev_dbg(dev, "releasing...\n");
3084 * tty_register_device_attr - register a tty device
3085 * @driver: the tty driver that describes the tty device
3086 * @index: the index in the tty driver for this tty device
3087 * @device: a struct device that is associated with this tty device.
3088 * This field is optional, if there is no known struct device
3089 * for this tty device it can be set to NULL safely.
3090 * @drvdata: Driver data to be set to device.
3091 * @attr_grp: Attribute group to be set on device.
3093 * Returns a pointer to the struct device for this tty device
3094 * (or ERR_PTR(-EFOO) on error).
3096 * This call is required to be made to register an individual tty device
3097 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3098 * that bit is not set, this function should not be called by a tty
3103 struct device *tty_register_device_attr(struct tty_driver *driver,
3104 unsigned index, struct device *device,
3106 const struct attribute_group **attr_grp)
3109 dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
3110 struct ktermios *tp;
3114 if (index >= driver->num) {
3115 pr_err("%s: Attempt to register invalid tty line number (%d)\n",
3116 driver->name, index);
3117 return ERR_PTR(-EINVAL);
3120 if (driver->type == TTY_DRIVER_TYPE_PTY)
3121 pty_line_name(driver, index, name);
3123 tty_line_name(driver, index, name);
3125 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
3127 return ERR_PTR(-ENOMEM);
3130 dev->class = tty_class;
3131 dev->parent = device;
3132 dev->release = tty_device_create_release;
3133 dev_set_name(dev, "%s", name);
3134 dev->groups = attr_grp;
3135 dev_set_drvdata(dev, drvdata);
3137 dev_set_uevent_suppress(dev, 1);
3139 retval = device_register(dev);
3143 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3145 * Free any saved termios data so that the termios state is
3146 * reset when reusing a minor number.
3148 tp = driver->termios[index];
3150 driver->termios[index] = NULL;
3154 retval = tty_cdev_add(driver, devt, index, 1);
3159 dev_set_uevent_suppress(dev, 0);
3160 kobject_uevent(&dev->kobj, KOBJ_ADD);
3169 return ERR_PTR(retval);
3171 EXPORT_SYMBOL_GPL(tty_register_device_attr);
3174 * tty_unregister_device - unregister a tty device
3175 * @driver: the tty driver that describes the tty device
3176 * @index: the index in the tty driver for this tty device
3178 * If a tty device is registered with a call to tty_register_device() then
3179 * this function must be called when the tty device is gone.
3184 void tty_unregister_device(struct tty_driver *driver, unsigned index)
3186 device_destroy(tty_class,
3187 MKDEV(driver->major, driver->minor_start) + index);
3188 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3189 cdev_del(driver->cdevs[index]);
3190 driver->cdevs[index] = NULL;
3193 EXPORT_SYMBOL(tty_unregister_device);
3196 * __tty_alloc_driver -- allocate tty driver
3197 * @lines: count of lines this driver can handle at most
3198 * @owner: module which is responsible for this driver
3199 * @flags: some of TTY_DRIVER_* flags, will be set in driver->flags
3201 * This should not be called directly, some of the provided macros should be
3202 * used instead. Use IS_ERR and friends on @retval.
3204 struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
3205 unsigned long flags)
3207 struct tty_driver *driver;
3208 unsigned int cdevs = 1;
3211 if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
3212 return ERR_PTR(-EINVAL);
3214 driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
3216 return ERR_PTR(-ENOMEM);
3218 kref_init(&driver->kref);
3219 driver->magic = TTY_DRIVER_MAGIC;
3220 driver->num = lines;
3221 driver->owner = owner;
3222 driver->flags = flags;
3224 if (!(flags & TTY_DRIVER_DEVPTS_MEM)) {
3225 driver->ttys = kcalloc(lines, sizeof(*driver->ttys),
3227 driver->termios = kcalloc(lines, sizeof(*driver->termios),
3229 if (!driver->ttys || !driver->termios) {
3235 if (!(flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3236 driver->ports = kcalloc(lines, sizeof(*driver->ports),
3238 if (!driver->ports) {
3245 driver->cdevs = kcalloc(cdevs, sizeof(*driver->cdevs), GFP_KERNEL);
3246 if (!driver->cdevs) {
3253 kfree(driver->ports);
3254 kfree(driver->ttys);
3255 kfree(driver->termios);
3256 kfree(driver->cdevs);
3258 return ERR_PTR(err);
3260 EXPORT_SYMBOL(__tty_alloc_driver);
3262 static void destruct_tty_driver(struct kref *kref)
3264 struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
3266 struct ktermios *tp;
3268 if (driver->flags & TTY_DRIVER_INSTALLED) {
3269 for (i = 0; i < driver->num; i++) {
3270 tp = driver->termios[i];
3272 driver->termios[i] = NULL;
3275 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3276 tty_unregister_device(driver, i);
3278 proc_tty_unregister_driver(driver);
3279 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
3280 cdev_del(driver->cdevs[0]);
3282 kfree(driver->cdevs);
3283 kfree(driver->ports);
3284 kfree(driver->termios);
3285 kfree(driver->ttys);
3289 void tty_driver_kref_put(struct tty_driver *driver)
3291 kref_put(&driver->kref, destruct_tty_driver);
3293 EXPORT_SYMBOL(tty_driver_kref_put);
3295 void tty_set_operations(struct tty_driver *driver,
3296 const struct tty_operations *op)
3300 EXPORT_SYMBOL(tty_set_operations);
3302 void put_tty_driver(struct tty_driver *d)
3304 tty_driver_kref_put(d);
3306 EXPORT_SYMBOL(put_tty_driver);
3309 * Called by a tty driver to register itself.
3311 int tty_register_driver(struct tty_driver *driver)
3318 if (!driver->major) {
3319 error = alloc_chrdev_region(&dev, driver->minor_start,
3320 driver->num, driver->name);
3322 driver->major = MAJOR(dev);
3323 driver->minor_start = MINOR(dev);
3326 dev = MKDEV(driver->major, driver->minor_start);
3327 error = register_chrdev_region(dev, driver->num, driver->name);
3332 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) {
3333 error = tty_cdev_add(driver, dev, 0, driver->num);
3335 goto err_unreg_char;
3338 mutex_lock(&tty_mutex);
3339 list_add(&driver->tty_drivers, &tty_drivers);
3340 mutex_unlock(&tty_mutex);
3342 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
3343 for (i = 0; i < driver->num; i++) {
3344 d = tty_register_device(driver, i, NULL);
3347 goto err_unreg_devs;
3351 proc_tty_register_driver(driver);
3352 driver->flags |= TTY_DRIVER_INSTALLED;
3356 for (i--; i >= 0; i--)
3357 tty_unregister_device(driver, i);
3359 mutex_lock(&tty_mutex);
3360 list_del(&driver->tty_drivers);
3361 mutex_unlock(&tty_mutex);
3364 unregister_chrdev_region(dev, driver->num);
3368 EXPORT_SYMBOL(tty_register_driver);
3371 * Called by a tty driver to unregister itself.
3373 int tty_unregister_driver(struct tty_driver *driver)
3377 if (driver->refcount)
3380 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3382 mutex_lock(&tty_mutex);
3383 list_del(&driver->tty_drivers);
3384 mutex_unlock(&tty_mutex);
3388 EXPORT_SYMBOL(tty_unregister_driver);
3390 dev_t tty_devnum(struct tty_struct *tty)
3392 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3394 EXPORT_SYMBOL(tty_devnum);
3396 void tty_default_fops(struct file_operations *fops)
3401 static char *tty_devnode(struct device *dev, umode_t *mode)
3405 if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
3406 dev->devt == MKDEV(TTYAUX_MAJOR, 2))
3411 static int __init tty_class_init(void)
3413 tty_class = class_create(THIS_MODULE, "tty");
3414 if (IS_ERR(tty_class))
3415 return PTR_ERR(tty_class);
3416 tty_class->devnode = tty_devnode;
3420 postcore_initcall(tty_class_init);
3422 /* 3/2004 jmc: why do these devices exist? */
3423 static struct cdev tty_cdev, console_cdev;
3425 static ssize_t show_cons_active(struct device *dev,
3426 struct device_attribute *attr, char *buf)
3428 struct console *cs[16];
3434 for_each_console(c) {
3439 if ((c->flags & CON_ENABLED) == 0)
3442 if (i >= ARRAY_SIZE(cs))
3446 int index = cs[i]->index;
3447 struct tty_driver *drv = cs[i]->device(cs[i], &index);
3449 /* don't resolve tty0 as some programs depend on it */
3450 if (drv && (cs[i]->index > 0 || drv->major != TTY_MAJOR))
3451 count += tty_line_name(drv, index, buf + count);
3453 count += sprintf(buf + count, "%s%d",
3454 cs[i]->name, cs[i]->index);
3456 count += sprintf(buf + count, "%c", i ? ' ':'\n');
3462 static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
3464 static struct attribute *cons_dev_attrs[] = {
3465 &dev_attr_active.attr,
3469 ATTRIBUTE_GROUPS(cons_dev);
3471 static struct device *consdev;
3473 void console_sysfs_notify(void)
3476 sysfs_notify(&consdev->kobj, NULL, "active");
3480 * Ok, now we can initialize the rest of the tty devices and can count
3481 * on memory allocations, interrupts etc..
3483 int __init tty_init(void)
3485 cdev_init(&tty_cdev, &tty_fops);
3486 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3487 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3488 panic("Couldn't register /dev/tty driver\n");
3489 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
3491 cdev_init(&console_cdev, &console_fops);
3492 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3493 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3494 panic("Couldn't register /dev/console driver\n");
3495 consdev = device_create_with_groups(tty_class, NULL,
3496 MKDEV(TTYAUX_MAJOR, 1), NULL,
3497 cons_dev_groups, "console");
3498 if (IS_ERR(consdev))
3502 vty_init(&console_fops);