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;
1261 if (driver->type == TTY_DRIVER_TYPE_PTY &&
1262 driver->subtype == PTY_TYPE_MASTER)
1268 if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
1276 retval = tty_ldisc_reinit(tty, tty->termios.c_line);
1284 * tty_init_dev - initialise a tty device
1285 * @driver: tty driver we are opening a device on
1286 * @idx: device index
1287 * @ret_tty: returned tty structure
1289 * Prepare a tty device. This may not be a "new" clean device but
1290 * could also be an active device. The pty drivers require special
1291 * handling because of this.
1294 * The function is called under the tty_mutex, which
1295 * protects us from the tty struct or driver itself going away.
1297 * On exit the tty device has the line discipline attached and
1298 * a reference count of 1. If a pair was created for pty/tty use
1299 * and the other was a pty master then it too has a reference count of 1.
1301 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1302 * failed open. The new code protects the open with a mutex, so it's
1303 * really quite straightforward. The mutex locking can probably be
1304 * relaxed for the (most common) case of reopening a tty.
1307 struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
1309 struct tty_struct *tty;
1313 * First time open is complex, especially for PTY devices.
1314 * This code guarantees that either everything succeeds and the
1315 * TTY is ready for operation, or else the table slots are vacated
1316 * and the allocated memory released. (Except that the termios
1320 if (!try_module_get(driver->owner))
1321 return ERR_PTR(-ENODEV);
1323 tty = alloc_tty_struct(driver, idx);
1326 goto err_module_put;
1330 retval = tty_driver_install_tty(driver, tty);
1335 tty->port = driver->ports[idx];
1337 WARN_RATELIMIT(!tty->port,
1338 "%s: %s driver does not set tty->port. This will crash the kernel later. Fix the driver!\n",
1339 __func__, tty->driver->name);
1341 retval = tty_ldisc_lock(tty, 5 * HZ);
1343 goto err_release_lock;
1344 tty->port->itty = tty;
1347 * Structures all installed ... call the ldisc open routines.
1348 * If we fail here just call release_tty to clean up. No need
1349 * to decrement the use counts, as release_tty doesn't care.
1351 retval = tty_ldisc_setup(tty, tty->link);
1353 goto err_release_tty;
1354 tty_ldisc_unlock(tty);
1355 /* Return the tty locked so that it cannot vanish under the caller */
1360 free_tty_struct(tty);
1362 module_put(driver->owner);
1363 return ERR_PTR(retval);
1365 /* call the tty release_tty routine to clean out this slot */
1367 tty_ldisc_unlock(tty);
1368 tty_info_ratelimited(tty, "ldisc open failed (%d), clearing slot %d\n",
1372 release_tty(tty, idx);
1373 return ERR_PTR(retval);
1377 * tty_save_termios() - save tty termios data in driver table
1378 * @tty: tty whose termios data to save
1380 * Locking: Caller guarantees serialisation with tty_init_termios().
1382 void tty_save_termios(struct tty_struct *tty)
1384 struct ktermios *tp;
1385 int idx = tty->index;
1387 /* If the port is going to reset then it has no termios to save */
1388 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1391 /* Stash the termios data */
1392 tp = tty->driver->termios[idx];
1394 tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
1397 tty->driver->termios[idx] = tp;
1401 EXPORT_SYMBOL_GPL(tty_save_termios);
1404 * tty_flush_works - flush all works of a tty/pty pair
1405 * @tty: tty device to flush works for (or either end of a pty pair)
1407 * Sync flush all works belonging to @tty (and the 'other' tty).
1409 static void tty_flush_works(struct tty_struct *tty)
1411 flush_work(&tty->SAK_work);
1412 flush_work(&tty->hangup_work);
1414 flush_work(&tty->link->SAK_work);
1415 flush_work(&tty->link->hangup_work);
1420 * release_one_tty - release tty structure memory
1421 * @kref: kref of tty we are obliterating
1423 * Releases memory associated with a tty structure, and clears out the
1424 * driver table slots. This function is called when a device is no longer
1425 * in use. It also gets called when setup of a device fails.
1428 * takes the file list lock internally when working on the list
1429 * of ttys that the driver keeps.
1431 * This method gets called from a work queue so that the driver private
1432 * cleanup ops can sleep (needed for USB at least)
1434 static void release_one_tty(struct work_struct *work)
1436 struct tty_struct *tty =
1437 container_of(work, struct tty_struct, hangup_work);
1438 struct tty_driver *driver = tty->driver;
1439 struct module *owner = driver->owner;
1441 if (tty->ops->cleanup)
1442 tty->ops->cleanup(tty);
1445 tty_driver_kref_put(driver);
1448 spin_lock(&tty->files_lock);
1449 list_del_init(&tty->tty_files);
1450 spin_unlock(&tty->files_lock);
1453 put_pid(tty->session);
1454 free_tty_struct(tty);
1457 static void queue_release_one_tty(struct kref *kref)
1459 struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1461 /* The hangup queue is now free so we can reuse it rather than
1462 waste a chunk of memory for each port */
1463 INIT_WORK(&tty->hangup_work, release_one_tty);
1464 schedule_work(&tty->hangup_work);
1468 * tty_kref_put - release a tty kref
1471 * Release a reference to a tty device and if need be let the kref
1472 * layer destruct the object for us
1475 void tty_kref_put(struct tty_struct *tty)
1478 kref_put(&tty->kref, queue_release_one_tty);
1480 EXPORT_SYMBOL(tty_kref_put);
1483 * release_tty - release tty structure memory
1485 * Release both @tty and a possible linked partner (think pty pair),
1486 * and decrement the refcount of the backing module.
1490 * takes the file list lock internally when working on the list
1491 * of ttys that the driver keeps.
1494 static void release_tty(struct tty_struct *tty, int idx)
1496 /* This should always be true but check for the moment */
1497 WARN_ON(tty->index != idx);
1498 WARN_ON(!mutex_is_locked(&tty_mutex));
1499 if (tty->ops->shutdown)
1500 tty->ops->shutdown(tty);
1501 tty_save_termios(tty);
1502 tty_driver_remove_tty(tty->driver, tty);
1503 tty->port->itty = NULL;
1505 tty->link->port->itty = NULL;
1506 tty_buffer_cancel_work(tty->port);
1508 tty_buffer_cancel_work(tty->link->port);
1510 tty_kref_put(tty->link);
1515 * tty_release_checks - check a tty before real release
1516 * @tty: tty to check
1517 * @o_tty: link of @tty (if any)
1518 * @idx: index of the tty
1520 * Performs some paranoid checking before true release of the @tty.
1521 * This is a no-op unless TTY_PARANOIA_CHECK is defined.
1523 static int tty_release_checks(struct tty_struct *tty, int idx)
1525 #ifdef TTY_PARANOIA_CHECK
1526 if (idx < 0 || idx >= tty->driver->num) {
1527 tty_debug(tty, "bad idx %d\n", idx);
1531 /* not much to check for devpts */
1532 if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)
1535 if (tty != tty->driver->ttys[idx]) {
1536 tty_debug(tty, "bad driver table[%d] = %p\n",
1537 idx, tty->driver->ttys[idx]);
1540 if (tty->driver->other) {
1541 struct tty_struct *o_tty = tty->link;
1543 if (o_tty != tty->driver->other->ttys[idx]) {
1544 tty_debug(tty, "bad other table[%d] = %p\n",
1545 idx, tty->driver->other->ttys[idx]);
1548 if (o_tty->link != tty) {
1549 tty_debug(tty, "bad link = %p\n", o_tty->link);
1558 * tty_kclose - closes tty opened by tty_kopen
1561 * Performs the final steps to release and free a tty device. It is the
1562 * same as tty_release_struct except that it also resets TTY_PORT_KOPENED
1563 * flag on tty->port.
1565 void tty_kclose(struct tty_struct *tty)
1568 * Ask the line discipline code to release its structures
1570 tty_ldisc_release(tty);
1572 /* Wait for pending work before tty destruction commmences */
1573 tty_flush_works(tty);
1575 tty_debug_hangup(tty, "freeing structure\n");
1577 * The release_tty function takes care of the details of clearing
1578 * the slots and preserving the termios structure. The tty_unlock_pair
1579 * should be safe as we keep a kref while the tty is locked (so the
1580 * unlock never unlocks a freed tty).
1582 mutex_lock(&tty_mutex);
1583 tty_port_set_kopened(tty->port, 0);
1584 release_tty(tty, tty->index);
1585 mutex_unlock(&tty_mutex);
1587 EXPORT_SYMBOL_GPL(tty_kclose);
1590 * tty_release_struct - release a tty struct
1592 * @idx: index of the tty
1594 * Performs the final steps to release and free a tty device. It is
1595 * roughly the reverse of tty_init_dev.
1597 void tty_release_struct(struct tty_struct *tty, int idx)
1600 * Ask the line discipline code to release its structures
1602 tty_ldisc_release(tty);
1604 /* Wait for pending work before tty destruction commmences */
1605 tty_flush_works(tty);
1607 tty_debug_hangup(tty, "freeing structure\n");
1609 * The release_tty function takes care of the details of clearing
1610 * the slots and preserving the termios structure. The tty_unlock_pair
1611 * should be safe as we keep a kref while the tty is locked (so the
1612 * unlock never unlocks a freed tty).
1614 mutex_lock(&tty_mutex);
1615 release_tty(tty, idx);
1616 mutex_unlock(&tty_mutex);
1618 EXPORT_SYMBOL_GPL(tty_release_struct);
1621 * tty_release - vfs callback for close
1622 * @inode: inode of tty
1623 * @filp: file pointer for handle to tty
1625 * Called the last time each file handle is closed that references
1626 * this tty. There may however be several such references.
1629 * Takes bkl. See tty_release_dev
1631 * Even releasing the tty structures is a tricky business.. We have
1632 * to be very careful that the structures are all released at the
1633 * same time, as interrupts might otherwise get the wrong pointers.
1635 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1636 * lead to double frees or releasing memory still in use.
1639 int tty_release(struct inode *inode, struct file *filp)
1641 struct tty_struct *tty = file_tty(filp);
1642 struct tty_struct *o_tty = NULL;
1643 int do_sleep, final;
1648 if (tty_paranoia_check(tty, inode, __func__))
1652 check_tty_count(tty, __func__);
1654 __tty_fasync(-1, filp, 0);
1657 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1658 tty->driver->subtype == PTY_TYPE_MASTER)
1661 if (tty_release_checks(tty, idx)) {
1666 tty_debug_hangup(tty, "releasing (count=%d)\n", tty->count);
1668 if (tty->ops->close)
1669 tty->ops->close(tty, filp);
1671 /* If tty is pty master, lock the slave pty (stable lock order) */
1672 tty_lock_slave(o_tty);
1675 * Sanity check: if tty->count is going to zero, there shouldn't be
1676 * any waiters on tty->read_wait or tty->write_wait. We test the
1677 * wait queues and kick everyone out _before_ actually starting to
1678 * close. This ensures that we won't block while releasing the tty
1681 * The test for the o_tty closing is necessary, since the master and
1682 * slave sides may close in any order. If the slave side closes out
1683 * first, its count will be one, since the master side holds an open.
1684 * Thus this test wouldn't be triggered at the time the slave closed,
1690 if (tty->count <= 1) {
1691 if (waitqueue_active(&tty->read_wait)) {
1692 wake_up_poll(&tty->read_wait, EPOLLIN);
1695 if (waitqueue_active(&tty->write_wait)) {
1696 wake_up_poll(&tty->write_wait, EPOLLOUT);
1700 if (o_tty && o_tty->count <= 1) {
1701 if (waitqueue_active(&o_tty->read_wait)) {
1702 wake_up_poll(&o_tty->read_wait, EPOLLIN);
1705 if (waitqueue_active(&o_tty->write_wait)) {
1706 wake_up_poll(&o_tty->write_wait, EPOLLOUT);
1715 tty_warn(tty, "read/write wait queue active!\n");
1717 schedule_timeout_killable(timeout);
1718 if (timeout < 120 * HZ)
1719 timeout = 2 * timeout + 1;
1721 timeout = MAX_SCHEDULE_TIMEOUT;
1725 if (--o_tty->count < 0) {
1726 tty_warn(tty, "bad slave count (%d)\n", o_tty->count);
1730 if (--tty->count < 0) {
1731 tty_warn(tty, "bad tty->count (%d)\n", tty->count);
1736 * We've decremented tty->count, so we need to remove this file
1737 * descriptor off the tty->tty_files list; this serves two
1739 * - check_tty_count sees the correct number of file descriptors
1740 * associated with this tty.
1741 * - do_tty_hangup no longer sees this file descriptor as
1742 * something that needs to be handled for hangups.
1747 * Perform some housekeeping before deciding whether to return.
1749 * If _either_ side is closing, make sure there aren't any
1750 * processes that still think tty or o_tty is their controlling
1754 read_lock(&tasklist_lock);
1755 session_clear_tty(tty->session);
1757 session_clear_tty(o_tty->session);
1758 read_unlock(&tasklist_lock);
1761 /* check whether both sides are closing ... */
1762 final = !tty->count && !(o_tty && o_tty->count);
1764 tty_unlock_slave(o_tty);
1767 /* At this point, the tty->count == 0 should ensure a dead tty
1768 cannot be re-opened by a racing opener */
1773 tty_debug_hangup(tty, "final close\n");
1775 tty_release_struct(tty, idx);
1780 * tty_open_current_tty - get locked tty of current task
1781 * @device: device number
1782 * @filp: file pointer to tty
1783 * @return: locked tty of the current task iff @device is /dev/tty
1785 * Performs a re-open of the current task's controlling tty.
1787 * We cannot return driver and index like for the other nodes because
1788 * devpts will not work then. It expects inodes to be from devpts FS.
1790 static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
1792 struct tty_struct *tty;
1795 if (device != MKDEV(TTYAUX_MAJOR, 0))
1798 tty = get_current_tty();
1800 return ERR_PTR(-ENXIO);
1802 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1805 tty_kref_put(tty); /* safe to drop the kref now */
1807 retval = tty_reopen(tty);
1810 tty = ERR_PTR(retval);
1816 * tty_lookup_driver - lookup a tty driver for a given device file
1817 * @device: device number
1818 * @filp: file pointer to tty
1819 * @index: index for the device in the @return driver
1820 * @return: driver for this inode (with increased refcount)
1822 * If @return is not erroneous, the caller is responsible to decrement the
1823 * refcount by tty_driver_kref_put.
1825 * Locking: tty_mutex protects get_tty_driver
1827 static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
1830 struct tty_driver *driver;
1834 case MKDEV(TTY_MAJOR, 0): {
1835 extern struct tty_driver *console_driver;
1836 driver = tty_driver_kref_get(console_driver);
1837 *index = fg_console;
1841 case MKDEV(TTYAUX_MAJOR, 1): {
1842 struct tty_driver *console_driver = console_device(index);
1843 if (console_driver) {
1844 driver = tty_driver_kref_get(console_driver);
1845 if (driver && filp) {
1846 /* Don't let /dev/console block */
1847 filp->f_flags |= O_NONBLOCK;
1851 return ERR_PTR(-ENODEV);
1854 driver = get_tty_driver(device, index);
1856 return ERR_PTR(-ENODEV);
1863 * tty_kopen - open a tty device for kernel
1864 * @device: dev_t of device to open
1866 * Opens tty exclusively for kernel. Performs the driver lookup,
1867 * makes sure it's not already opened and performs the first-time
1868 * tty initialization.
1870 * Returns the locked initialized &tty_struct
1872 * Claims the global tty_mutex to serialize:
1873 * - concurrent first-time tty initialization
1874 * - concurrent tty driver removal w/ lookup
1875 * - concurrent tty removal from driver table
1877 struct tty_struct *tty_kopen(dev_t device)
1879 struct tty_struct *tty;
1880 struct tty_driver *driver = NULL;
1883 mutex_lock(&tty_mutex);
1884 driver = tty_lookup_driver(device, NULL, &index);
1885 if (IS_ERR(driver)) {
1886 mutex_unlock(&tty_mutex);
1887 return ERR_CAST(driver);
1890 /* check whether we're reopening an existing tty */
1891 tty = tty_driver_lookup_tty(driver, NULL, index);
1896 /* drop kref from tty_driver_lookup_tty() */
1898 tty = ERR_PTR(-EBUSY);
1899 } else { /* tty_init_dev returns tty with the tty_lock held */
1900 tty = tty_init_dev(driver, index);
1903 tty_port_set_kopened(tty->port, 1);
1906 mutex_unlock(&tty_mutex);
1907 tty_driver_kref_put(driver);
1910 EXPORT_SYMBOL_GPL(tty_kopen);
1913 * tty_open_by_driver - open a tty device
1914 * @device: dev_t of device to open
1915 * @inode: inode of device file
1916 * @filp: file pointer to tty
1918 * Performs the driver lookup, checks for a reopen, or otherwise
1919 * performs the first-time tty initialization.
1921 * Returns the locked initialized or re-opened &tty_struct
1923 * Claims the global tty_mutex to serialize:
1924 * - concurrent first-time tty initialization
1925 * - concurrent tty driver removal w/ lookup
1926 * - concurrent tty removal from driver table
1928 static struct tty_struct *tty_open_by_driver(dev_t device, struct inode *inode,
1931 struct tty_struct *tty;
1932 struct tty_driver *driver = NULL;
1936 mutex_lock(&tty_mutex);
1937 driver = tty_lookup_driver(device, filp, &index);
1938 if (IS_ERR(driver)) {
1939 mutex_unlock(&tty_mutex);
1940 return ERR_CAST(driver);
1943 /* check whether we're reopening an existing tty */
1944 tty = tty_driver_lookup_tty(driver, filp, index);
1946 mutex_unlock(&tty_mutex);
1951 if (tty_port_kopened(tty->port)) {
1953 mutex_unlock(&tty_mutex);
1954 tty = ERR_PTR(-EBUSY);
1957 mutex_unlock(&tty_mutex);
1958 retval = tty_lock_interruptible(tty);
1959 tty_kref_put(tty); /* drop kref from tty_driver_lookup_tty() */
1961 if (retval == -EINTR)
1962 retval = -ERESTARTSYS;
1963 tty = ERR_PTR(retval);
1966 retval = tty_reopen(tty);
1969 tty = ERR_PTR(retval);
1971 } else { /* Returns with the tty_lock held for now */
1972 tty = tty_init_dev(driver, index);
1973 mutex_unlock(&tty_mutex);
1976 tty_driver_kref_put(driver);
1981 * tty_open - open a tty device
1982 * @inode: inode of device file
1983 * @filp: file pointer to tty
1985 * tty_open and tty_release keep up the tty count that contains the
1986 * number of opens done on a tty. We cannot use the inode-count, as
1987 * different inodes might point to the same tty.
1989 * Open-counting is needed for pty masters, as well as for keeping
1990 * track of serial lines: DTR is dropped when the last close happens.
1991 * (This is not done solely through tty->count, now. - Ted 1/27/92)
1993 * The termios state of a pty is reset on first open so that
1994 * settings don't persist across reuse.
1996 * Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.
1997 * tty->count should protect the rest.
1998 * ->siglock protects ->signal/->sighand
2000 * Note: the tty_unlock/lock cases without a ref are only safe due to
2004 static int tty_open(struct inode *inode, struct file *filp)
2006 struct tty_struct *tty;
2008 dev_t device = inode->i_rdev;
2009 unsigned saved_flags = filp->f_flags;
2011 nonseekable_open(inode, filp);
2014 retval = tty_alloc_file(filp);
2018 tty = tty_open_current_tty(device, filp);
2020 tty = tty_open_by_driver(device, inode, filp);
2023 tty_free_file(filp);
2024 retval = PTR_ERR(tty);
2025 if (retval != -EAGAIN || signal_pending(current))
2031 tty_add_file(tty, filp);
2033 check_tty_count(tty, __func__);
2034 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
2037 retval = tty->ops->open(tty, filp);
2040 filp->f_flags = saved_flags;
2043 tty_debug_hangup(tty, "open error %d, releasing\n", retval);
2045 tty_unlock(tty); /* need to call tty_release without BTM */
2046 tty_release(inode, filp);
2047 if (retval != -ERESTARTSYS)
2050 if (signal_pending(current))
2055 * Need to reset f_op in case a hangup happened.
2057 if (tty_hung_up_p(filp))
2058 filp->f_op = &tty_fops;
2061 clear_bit(TTY_HUPPED, &tty->flags);
2063 noctty = (filp->f_flags & O_NOCTTY) ||
2064 (IS_ENABLED(CONFIG_VT) && device == MKDEV(TTY_MAJOR, 0)) ||
2065 device == MKDEV(TTYAUX_MAJOR, 1) ||
2066 (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2067 tty->driver->subtype == PTY_TYPE_MASTER);
2069 tty_open_proc_set_tty(filp, tty);
2077 * tty_poll - check tty status
2078 * @filp: file being polled
2079 * @wait: poll wait structures to update
2081 * Call the line discipline polling method to obtain the poll
2082 * status of the device.
2084 * Locking: locks called line discipline but ldisc poll method
2085 * may be re-entered freely by other callers.
2088 static __poll_t tty_poll(struct file *filp, poll_table *wait)
2090 struct tty_struct *tty = file_tty(filp);
2091 struct tty_ldisc *ld;
2094 if (tty_paranoia_check(tty, file_inode(filp), "tty_poll"))
2097 ld = tty_ldisc_ref_wait(tty);
2099 return hung_up_tty_poll(filp, wait);
2101 ret = ld->ops->poll(tty, filp, wait);
2102 tty_ldisc_deref(ld);
2106 static int __tty_fasync(int fd, struct file *filp, int on)
2108 struct tty_struct *tty = file_tty(filp);
2109 unsigned long flags;
2112 if (tty_paranoia_check(tty, file_inode(filp), "tty_fasync"))
2115 retval = fasync_helper(fd, filp, on, &tty->fasync);
2123 spin_lock_irqsave(&tty->ctrl_lock, flags);
2126 type = PIDTYPE_PGID;
2128 pid = task_pid(current);
2129 type = PIDTYPE_TGID;
2132 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2133 __f_setown(filp, pid, type, 0);
2141 static int tty_fasync(int fd, struct file *filp, int on)
2143 struct tty_struct *tty = file_tty(filp);
2144 int retval = -ENOTTY;
2147 if (!tty_hung_up_p(filp))
2148 retval = __tty_fasync(fd, filp, on);
2155 * tiocsti - fake input character
2156 * @tty: tty to fake input into
2157 * @p: pointer to character
2159 * Fake input to a tty device. Does the necessary locking and
2162 * FIXME: does not honour flow control ??
2165 * Called functions take tty_ldiscs_lock
2166 * current->signal->tty check is safe without locks
2168 * FIXME: may race normal receive processing
2171 static int tiocsti(struct tty_struct *tty, char __user *p)
2174 struct tty_ldisc *ld;
2176 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2178 if (get_user(ch, p))
2180 tty_audit_tiocsti(tty, ch);
2181 ld = tty_ldisc_ref_wait(tty);
2184 ld->ops->receive_buf(tty, &ch, &mbz, 1);
2185 tty_ldisc_deref(ld);
2190 * tiocgwinsz - implement window query ioctl
2192 * @arg: user buffer for result
2194 * Copies the kernel idea of the window size into the user buffer.
2196 * Locking: tty->winsize_mutex is taken to ensure the winsize data
2200 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2204 mutex_lock(&tty->winsize_mutex);
2205 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2206 mutex_unlock(&tty->winsize_mutex);
2208 return err ? -EFAULT: 0;
2212 * tty_do_resize - resize event
2213 * @tty: tty being resized
2214 * @rows: rows (character)
2215 * @cols: cols (character)
2217 * Update the termios variables and send the necessary signals to
2218 * peform a terminal resize correctly
2221 int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
2226 mutex_lock(&tty->winsize_mutex);
2227 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
2230 /* Signal the foreground process group */
2231 pgrp = tty_get_pgrp(tty);
2233 kill_pgrp(pgrp, SIGWINCH, 1);
2238 mutex_unlock(&tty->winsize_mutex);
2241 EXPORT_SYMBOL(tty_do_resize);
2244 * tiocswinsz - implement window size set ioctl
2245 * @tty; tty side of tty
2246 * @arg: user buffer for result
2248 * Copies the user idea of the window size to the kernel. Traditionally
2249 * this is just advisory information but for the Linux console it
2250 * actually has driver level meaning and triggers a VC resize.
2253 * Driver dependent. The default do_resize method takes the
2254 * tty termios mutex and ctrl_lock. The console takes its own lock
2255 * then calls into the default method.
2258 static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
2260 struct winsize tmp_ws;
2261 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2264 if (tty->ops->resize)
2265 return tty->ops->resize(tty, &tmp_ws);
2267 return tty_do_resize(tty, &tmp_ws);
2271 * tioccons - allow admin to move logical console
2272 * @file: the file to become console
2274 * Allow the administrator to move the redirected console device
2276 * Locking: uses redirect_lock to guard the redirect information
2279 static int tioccons(struct file *file)
2281 if (!capable(CAP_SYS_ADMIN))
2283 if (file->f_op->write == redirected_tty_write) {
2285 spin_lock(&redirect_lock);
2288 spin_unlock(&redirect_lock);
2293 spin_lock(&redirect_lock);
2295 spin_unlock(&redirect_lock);
2298 redirect = get_file(file);
2299 spin_unlock(&redirect_lock);
2304 * tiocsetd - set line discipline
2306 * @p: pointer to user data
2308 * Set the line discipline according to user request.
2310 * Locking: see tty_set_ldisc, this function is just a helper
2313 static int tiocsetd(struct tty_struct *tty, int __user *p)
2318 if (get_user(disc, p))
2321 ret = tty_set_ldisc(tty, disc);
2327 * tiocgetd - get line discipline
2329 * @p: pointer to user data
2331 * Retrieves the line discipline id directly from the ldisc.
2333 * Locking: waits for ldisc reference (in case the line discipline
2334 * is changing or the tty is being hungup)
2337 static int tiocgetd(struct tty_struct *tty, int __user *p)
2339 struct tty_ldisc *ld;
2342 ld = tty_ldisc_ref_wait(tty);
2345 ret = put_user(ld->ops->num, p);
2346 tty_ldisc_deref(ld);
2351 * send_break - performed time break
2352 * @tty: device to break on
2353 * @duration: timeout in mS
2355 * Perform a timed break on hardware that lacks its own driver level
2356 * timed break functionality.
2359 * atomic_write_lock serializes
2363 static int send_break(struct tty_struct *tty, unsigned int duration)
2367 if (tty->ops->break_ctl == NULL)
2370 if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2371 retval = tty->ops->break_ctl(tty, duration);
2373 /* Do the work ourselves */
2374 if (tty_write_lock(tty, 0) < 0)
2376 retval = tty->ops->break_ctl(tty, -1);
2379 if (!signal_pending(current))
2380 msleep_interruptible(duration);
2381 retval = tty->ops->break_ctl(tty, 0);
2383 tty_write_unlock(tty);
2384 if (signal_pending(current))
2391 * tty_tiocmget - get modem status
2393 * @file: user file pointer
2394 * @p: pointer to result
2396 * Obtain the modem status bits from the tty driver if the feature
2397 * is supported. Return -EINVAL if it is not available.
2399 * Locking: none (up to the driver)
2402 static int tty_tiocmget(struct tty_struct *tty, int __user *p)
2404 int retval = -EINVAL;
2406 if (tty->ops->tiocmget) {
2407 retval = tty->ops->tiocmget(tty);
2410 retval = put_user(retval, p);
2416 * tty_tiocmset - set modem status
2418 * @cmd: command - clear bits, set bits or set all
2419 * @p: pointer to desired bits
2421 * Set the modem status bits from the tty driver if the feature
2422 * is supported. Return -EINVAL if it is not available.
2424 * Locking: none (up to the driver)
2427 static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
2431 unsigned int set, clear, val;
2433 if (tty->ops->tiocmset == NULL)
2436 retval = get_user(val, p);
2452 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2453 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2454 return tty->ops->tiocmset(tty, set, clear);
2457 static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
2459 int retval = -EINVAL;
2460 struct serial_icounter_struct icount;
2461 memset(&icount, 0, sizeof(icount));
2462 if (tty->ops->get_icount)
2463 retval = tty->ops->get_icount(tty, &icount);
2466 if (copy_to_user(arg, &icount, sizeof(icount)))
2471 static int tty_tiocsserial(struct tty_struct *tty, struct serial_struct __user *ss)
2473 static DEFINE_RATELIMIT_STATE(depr_flags,
2474 DEFAULT_RATELIMIT_INTERVAL,
2475 DEFAULT_RATELIMIT_BURST);
2476 char comm[TASK_COMM_LEN];
2477 struct serial_struct v;
2480 if (copy_from_user(&v, ss, sizeof(struct serial_struct)))
2483 flags = v.flags & ASYNC_DEPRECATED;
2485 if (flags && __ratelimit(&depr_flags))
2486 pr_warn("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
2487 __func__, get_task_comm(comm, current), flags);
2488 if (!tty->ops->set_serial)
2490 return tty->ops->set_serial(tty, &v);
2493 static int tty_tiocgserial(struct tty_struct *tty, struct serial_struct __user *ss)
2495 struct serial_struct v;
2498 memset(&v, 0, sizeof(struct serial_struct));
2499 if (!tty->ops->get_serial)
2501 err = tty->ops->get_serial(tty, &v);
2502 if (!err && copy_to_user(ss, &v, sizeof(struct serial_struct)))
2508 * if pty, return the slave side (real_tty)
2509 * otherwise, return self
2511 static struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
2513 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2514 tty->driver->subtype == PTY_TYPE_MASTER)
2520 * Split this up, as gcc can choke on it otherwise..
2522 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2524 struct tty_struct *tty = file_tty(file);
2525 struct tty_struct *real_tty;
2526 void __user *p = (void __user *)arg;
2528 struct tty_ldisc *ld;
2530 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2533 real_tty = tty_pair_get_tty(tty);
2536 * Factor out some common prep work
2544 retval = tty_check_change(tty);
2547 if (cmd != TIOCCBRK) {
2548 tty_wait_until_sent(tty, 0);
2549 if (signal_pending(current))
2560 return tiocsti(tty, p);
2562 return tiocgwinsz(real_tty, p);
2564 return tiocswinsz(real_tty, p);
2566 return real_tty != tty ? -EINVAL : tioccons(file);
2568 set_bit(TTY_EXCLUSIVE, &tty->flags);
2571 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2575 int excl = test_bit(TTY_EXCLUSIVE, &tty->flags);
2576 return put_user(excl, (int __user *)p);
2579 return tiocgetd(tty, p);
2581 return tiocsetd(tty, p);
2583 if (!capable(CAP_SYS_ADMIN))
2589 unsigned int ret = new_encode_dev(tty_devnum(real_tty));
2590 return put_user(ret, (unsigned int __user *)p);
2595 case TIOCSBRK: /* Turn break on, unconditionally */
2596 if (tty->ops->break_ctl)
2597 return tty->ops->break_ctl(tty, -1);
2599 case TIOCCBRK: /* Turn break off, unconditionally */
2600 if (tty->ops->break_ctl)
2601 return tty->ops->break_ctl(tty, 0);
2603 case TCSBRK: /* SVID version: non-zero arg --> no break */
2604 /* non-zero arg means wait for all output data
2605 * to be sent (performed above) but don't send break.
2606 * This is used by the tcdrain() termios function.
2609 return send_break(tty, 250);
2611 case TCSBRKP: /* support for POSIX tcsendbreak() */
2612 return send_break(tty, arg ? arg*100 : 250);
2615 return tty_tiocmget(tty, p);
2619 return tty_tiocmset(tty, cmd, p);
2621 return tty_tiocgicount(tty, p);
2626 /* flush tty buffer and allow ldisc to process ioctl */
2627 tty_buffer_flush(tty, NULL);
2632 return tty_tiocsserial(tty, p);
2634 return tty_tiocgserial(tty, p);
2636 /* Special because the struct file is needed */
2637 return ptm_open_peer(file, tty, (int)arg);
2639 retval = tty_jobctrl_ioctl(tty, real_tty, file, cmd, arg);
2640 if (retval != -ENOIOCTLCMD)
2643 if (tty->ops->ioctl) {
2644 retval = tty->ops->ioctl(tty, cmd, arg);
2645 if (retval != -ENOIOCTLCMD)
2648 ld = tty_ldisc_ref_wait(tty);
2650 return hung_up_tty_ioctl(file, cmd, arg);
2652 if (ld->ops->ioctl) {
2653 retval = ld->ops->ioctl(tty, file, cmd, arg);
2654 if (retval == -ENOIOCTLCMD)
2657 tty_ldisc_deref(ld);
2661 #ifdef CONFIG_COMPAT
2663 struct serial_struct32 {
2669 compat_int_t xmit_fifo_size;
2670 compat_int_t custom_divisor;
2671 compat_int_t baud_base;
2672 unsigned short close_delay;
2674 char reserved_char[1];
2676 unsigned short closing_wait; /* time to wait before closing */
2677 unsigned short closing_wait2; /* no longer used... */
2678 compat_uint_t iomem_base;
2679 unsigned short iomem_reg_shift;
2680 unsigned int port_high;
2681 /* compat_ulong_t iomap_base FIXME */
2682 compat_int_t reserved[1];
2685 static int compat_tty_tiocsserial(struct tty_struct *tty,
2686 struct serial_struct32 __user *ss)
2688 static DEFINE_RATELIMIT_STATE(depr_flags,
2689 DEFAULT_RATELIMIT_INTERVAL,
2690 DEFAULT_RATELIMIT_BURST);
2691 char comm[TASK_COMM_LEN];
2692 struct serial_struct32 v32;
2693 struct serial_struct v;
2696 if (copy_from_user(&v32, ss, sizeof(struct serial_struct32)))
2699 memcpy(&v, &v32, offsetof(struct serial_struct32, iomem_base));
2700 v.iomem_base = compat_ptr(v32.iomem_base);
2701 v.iomem_reg_shift = v32.iomem_reg_shift;
2702 v.port_high = v32.port_high;
2705 flags = v.flags & ASYNC_DEPRECATED;
2707 if (flags && __ratelimit(&depr_flags))
2708 pr_warn("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
2709 __func__, get_task_comm(comm, current), flags);
2710 if (!tty->ops->set_serial)
2712 return tty->ops->set_serial(tty, &v);
2715 static int compat_tty_tiocgserial(struct tty_struct *tty,
2716 struct serial_struct32 __user *ss)
2718 struct serial_struct32 v32;
2719 struct serial_struct v;
2721 memset(&v, 0, sizeof(struct serial_struct));
2723 if (!tty->ops->set_serial)
2725 err = tty->ops->get_serial(tty, &v);
2727 memcpy(&v32, &v, offsetof(struct serial_struct32, iomem_base));
2728 v32.iomem_base = (unsigned long)v.iomem_base >> 32 ?
2729 0xfffffff : ptr_to_compat(v.iomem_base);
2730 v32.iomem_reg_shift = v.iomem_reg_shift;
2731 v32.port_high = v.port_high;
2732 if (copy_to_user(ss, &v32, sizeof(struct serial_struct32)))
2737 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2740 struct tty_struct *tty = file_tty(file);
2741 struct tty_ldisc *ld;
2742 int retval = -ENOIOCTLCMD;
2790 case TIOCGLCKTRMIOS:
2791 case TIOCSLCKTRMIOS:
2800 return tty_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
2816 return tty_ioctl(file, cmd, arg);
2819 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2824 return compat_tty_tiocsserial(tty, compat_ptr(arg));
2826 return compat_tty_tiocgserial(tty, compat_ptr(arg));
2828 if (tty->ops->compat_ioctl) {
2829 retval = tty->ops->compat_ioctl(tty, cmd, arg);
2830 if (retval != -ENOIOCTLCMD)
2834 ld = tty_ldisc_ref_wait(tty);
2836 return hung_up_tty_compat_ioctl(file, cmd, arg);
2837 if (ld->ops->compat_ioctl)
2838 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
2839 if (retval == -ENOIOCTLCMD && ld->ops->ioctl)
2840 retval = ld->ops->ioctl(tty, file,
2841 (unsigned long)compat_ptr(cmd), arg);
2842 tty_ldisc_deref(ld);
2848 static int this_tty(const void *t, struct file *file, unsigned fd)
2850 if (likely(file->f_op->read != tty_read))
2852 return file_tty(file) != t ? 0 : fd + 1;
2856 * This implements the "Secure Attention Key" --- the idea is to
2857 * prevent trojan horses by killing all processes associated with this
2858 * tty when the user hits the "Secure Attention Key". Required for
2859 * super-paranoid applications --- see the Orange Book for more details.
2861 * This code could be nicer; ideally it should send a HUP, wait a few
2862 * seconds, then send a INT, and then a KILL signal. But you then
2863 * have to coordinate with the init process, since all processes associated
2864 * with the current tty must be dead before the new getty is allowed
2867 * Now, if it would be correct ;-/ The current code has a nasty hole -
2868 * it doesn't catch files in flight. We may send the descriptor to ourselves
2869 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
2871 * Nasty bug: do_SAK is being called in interrupt context. This can
2872 * deadlock. We punt it up to process context. AKPM - 16Mar2001
2874 void __do_SAK(struct tty_struct *tty)
2879 struct task_struct *g, *p;
2880 struct pid *session;
2885 session = tty->session;
2887 tty_ldisc_flush(tty);
2889 tty_driver_flush_buffer(tty);
2891 read_lock(&tasklist_lock);
2892 /* Kill the entire session */
2893 do_each_pid_task(session, PIDTYPE_SID, p) {
2894 tty_notice(tty, "SAK: killed process %d (%s): by session\n",
2895 task_pid_nr(p), p->comm);
2896 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
2897 } while_each_pid_task(session, PIDTYPE_SID, p);
2899 /* Now kill any processes that happen to have the tty open */
2900 do_each_thread(g, p) {
2901 if (p->signal->tty == tty) {
2902 tty_notice(tty, "SAK: killed process %d (%s): by controlling tty\n",
2903 task_pid_nr(p), p->comm);
2904 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
2908 i = iterate_fd(p->files, 0, this_tty, tty);
2910 tty_notice(tty, "SAK: killed process %d (%s): by fd#%d\n",
2911 task_pid_nr(p), p->comm, i - 1);
2912 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
2915 } while_each_thread(g, p);
2916 read_unlock(&tasklist_lock);
2920 static void do_SAK_work(struct work_struct *work)
2922 struct tty_struct *tty =
2923 container_of(work, struct tty_struct, SAK_work);
2928 * The tq handling here is a little racy - tty->SAK_work may already be queued.
2929 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
2930 * the values which we write to it will be identical to the values which it
2931 * already has. --akpm
2933 void do_SAK(struct tty_struct *tty)
2937 schedule_work(&tty->SAK_work);
2940 EXPORT_SYMBOL(do_SAK);
2942 static int dev_match_devt(struct device *dev, const void *data)
2944 const dev_t *devt = data;
2945 return dev->devt == *devt;
2948 /* Must put_device() after it's unused! */
2949 static struct device *tty_get_device(struct tty_struct *tty)
2951 dev_t devt = tty_devnum(tty);
2952 return class_find_device(tty_class, NULL, &devt, dev_match_devt);
2959 * This subroutine allocates and initializes a tty structure.
2961 * Locking: none - tty in question is not exposed at this point
2964 struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
2966 struct tty_struct *tty;
2968 tty = kzalloc(sizeof(*tty), GFP_KERNEL);
2972 kref_init(&tty->kref);
2973 tty->magic = TTY_MAGIC;
2974 if (tty_ldisc_init(tty)) {
2978 tty->session = NULL;
2980 mutex_init(&tty->legacy_mutex);
2981 mutex_init(&tty->throttle_mutex);
2982 init_rwsem(&tty->termios_rwsem);
2983 mutex_init(&tty->winsize_mutex);
2984 init_ldsem(&tty->ldisc_sem);
2985 init_waitqueue_head(&tty->write_wait);
2986 init_waitqueue_head(&tty->read_wait);
2987 INIT_WORK(&tty->hangup_work, do_tty_hangup);
2988 mutex_init(&tty->atomic_write_lock);
2989 spin_lock_init(&tty->ctrl_lock);
2990 spin_lock_init(&tty->flow_lock);
2991 spin_lock_init(&tty->files_lock);
2992 INIT_LIST_HEAD(&tty->tty_files);
2993 INIT_WORK(&tty->SAK_work, do_SAK_work);
2995 tty->driver = driver;
2996 tty->ops = driver->ops;
2998 tty_line_name(driver, idx, tty->name);
2999 tty->dev = tty_get_device(tty);
3005 * tty_put_char - write one character to a tty
3009 * Write one byte to the tty using the provided put_char method
3010 * if present. Returns the number of characters successfully output.
3012 * Note: the specific put_char operation in the driver layer may go
3013 * away soon. Don't call it directly, use this method
3016 int tty_put_char(struct tty_struct *tty, unsigned char ch)
3018 if (tty->ops->put_char)
3019 return tty->ops->put_char(tty, ch);
3020 return tty->ops->write(tty, &ch, 1);
3022 EXPORT_SYMBOL_GPL(tty_put_char);
3024 struct class *tty_class;
3026 static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
3027 unsigned int index, unsigned int count)
3031 /* init here, since reused cdevs cause crashes */
3032 driver->cdevs[index] = cdev_alloc();
3033 if (!driver->cdevs[index])
3035 driver->cdevs[index]->ops = &tty_fops;
3036 driver->cdevs[index]->owner = driver->owner;
3037 err = cdev_add(driver->cdevs[index], dev, count);
3039 kobject_put(&driver->cdevs[index]->kobj);
3044 * tty_register_device - register a tty device
3045 * @driver: the tty driver that describes the tty device
3046 * @index: the index in the tty driver for this tty device
3047 * @device: a struct device that is associated with this tty device.
3048 * This field is optional, if there is no known struct device
3049 * for this tty device it can be set to NULL safely.
3051 * Returns a pointer to the struct device for this tty device
3052 * (or ERR_PTR(-EFOO) on error).
3054 * This call is required to be made to register an individual tty device
3055 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3056 * that bit is not set, this function should not be called by a tty
3062 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
3063 struct device *device)
3065 return tty_register_device_attr(driver, index, device, NULL, NULL);
3067 EXPORT_SYMBOL(tty_register_device);
3069 static void tty_device_create_release(struct device *dev)
3071 dev_dbg(dev, "releasing...\n");
3076 * tty_register_device_attr - register a tty device
3077 * @driver: the tty driver that describes the tty device
3078 * @index: the index in the tty driver for this tty device
3079 * @device: a struct device that is associated with this tty device.
3080 * This field is optional, if there is no known struct device
3081 * for this tty device it can be set to NULL safely.
3082 * @drvdata: Driver data to be set to device.
3083 * @attr_grp: Attribute group to be set on device.
3085 * Returns a pointer to the struct device for this tty device
3086 * (or ERR_PTR(-EFOO) on error).
3088 * This call is required to be made to register an individual tty device
3089 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3090 * that bit is not set, this function should not be called by a tty
3095 struct device *tty_register_device_attr(struct tty_driver *driver,
3096 unsigned index, struct device *device,
3098 const struct attribute_group **attr_grp)
3101 dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
3102 struct ktermios *tp;
3106 if (index >= driver->num) {
3107 pr_err("%s: Attempt to register invalid tty line number (%d)\n",
3108 driver->name, index);
3109 return ERR_PTR(-EINVAL);
3112 if (driver->type == TTY_DRIVER_TYPE_PTY)
3113 pty_line_name(driver, index, name);
3115 tty_line_name(driver, index, name);
3117 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
3119 return ERR_PTR(-ENOMEM);
3122 dev->class = tty_class;
3123 dev->parent = device;
3124 dev->release = tty_device_create_release;
3125 dev_set_name(dev, "%s", name);
3126 dev->groups = attr_grp;
3127 dev_set_drvdata(dev, drvdata);
3129 dev_set_uevent_suppress(dev, 1);
3131 retval = device_register(dev);
3135 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3137 * Free any saved termios data so that the termios state is
3138 * reset when reusing a minor number.
3140 tp = driver->termios[index];
3142 driver->termios[index] = NULL;
3146 retval = tty_cdev_add(driver, devt, index, 1);
3151 dev_set_uevent_suppress(dev, 0);
3152 kobject_uevent(&dev->kobj, KOBJ_ADD);
3161 return ERR_PTR(retval);
3163 EXPORT_SYMBOL_GPL(tty_register_device_attr);
3166 * tty_unregister_device - unregister a tty device
3167 * @driver: the tty driver that describes the tty device
3168 * @index: the index in the tty driver for this tty device
3170 * If a tty device is registered with a call to tty_register_device() then
3171 * this function must be called when the tty device is gone.
3176 void tty_unregister_device(struct tty_driver *driver, unsigned index)
3178 device_destroy(tty_class,
3179 MKDEV(driver->major, driver->minor_start) + index);
3180 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3181 cdev_del(driver->cdevs[index]);
3182 driver->cdevs[index] = NULL;
3185 EXPORT_SYMBOL(tty_unregister_device);
3188 * __tty_alloc_driver -- allocate tty driver
3189 * @lines: count of lines this driver can handle at most
3190 * @owner: module which is responsible for this driver
3191 * @flags: some of TTY_DRIVER_* flags, will be set in driver->flags
3193 * This should not be called directly, some of the provided macros should be
3194 * used instead. Use IS_ERR and friends on @retval.
3196 struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
3197 unsigned long flags)
3199 struct tty_driver *driver;
3200 unsigned int cdevs = 1;
3203 if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
3204 return ERR_PTR(-EINVAL);
3206 driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
3208 return ERR_PTR(-ENOMEM);
3210 kref_init(&driver->kref);
3211 driver->magic = TTY_DRIVER_MAGIC;
3212 driver->num = lines;
3213 driver->owner = owner;
3214 driver->flags = flags;
3216 if (!(flags & TTY_DRIVER_DEVPTS_MEM)) {
3217 driver->ttys = kcalloc(lines, sizeof(*driver->ttys),
3219 driver->termios = kcalloc(lines, sizeof(*driver->termios),
3221 if (!driver->ttys || !driver->termios) {
3227 if (!(flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3228 driver->ports = kcalloc(lines, sizeof(*driver->ports),
3230 if (!driver->ports) {
3237 driver->cdevs = kcalloc(cdevs, sizeof(*driver->cdevs), GFP_KERNEL);
3238 if (!driver->cdevs) {
3245 kfree(driver->ports);
3246 kfree(driver->ttys);
3247 kfree(driver->termios);
3248 kfree(driver->cdevs);
3250 return ERR_PTR(err);
3252 EXPORT_SYMBOL(__tty_alloc_driver);
3254 static void destruct_tty_driver(struct kref *kref)
3256 struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
3258 struct ktermios *tp;
3260 if (driver->flags & TTY_DRIVER_INSTALLED) {
3261 for (i = 0; i < driver->num; i++) {
3262 tp = driver->termios[i];
3264 driver->termios[i] = NULL;
3267 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3268 tty_unregister_device(driver, i);
3270 proc_tty_unregister_driver(driver);
3271 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
3272 cdev_del(driver->cdevs[0]);
3274 kfree(driver->cdevs);
3275 kfree(driver->ports);
3276 kfree(driver->termios);
3277 kfree(driver->ttys);
3281 void tty_driver_kref_put(struct tty_driver *driver)
3283 kref_put(&driver->kref, destruct_tty_driver);
3285 EXPORT_SYMBOL(tty_driver_kref_put);
3287 void tty_set_operations(struct tty_driver *driver,
3288 const struct tty_operations *op)
3292 EXPORT_SYMBOL(tty_set_operations);
3294 void put_tty_driver(struct tty_driver *d)
3296 tty_driver_kref_put(d);
3298 EXPORT_SYMBOL(put_tty_driver);
3301 * Called by a tty driver to register itself.
3303 int tty_register_driver(struct tty_driver *driver)
3310 if (!driver->major) {
3311 error = alloc_chrdev_region(&dev, driver->minor_start,
3312 driver->num, driver->name);
3314 driver->major = MAJOR(dev);
3315 driver->minor_start = MINOR(dev);
3318 dev = MKDEV(driver->major, driver->minor_start);
3319 error = register_chrdev_region(dev, driver->num, driver->name);
3324 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) {
3325 error = tty_cdev_add(driver, dev, 0, driver->num);
3327 goto err_unreg_char;
3330 mutex_lock(&tty_mutex);
3331 list_add(&driver->tty_drivers, &tty_drivers);
3332 mutex_unlock(&tty_mutex);
3334 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
3335 for (i = 0; i < driver->num; i++) {
3336 d = tty_register_device(driver, i, NULL);
3339 goto err_unreg_devs;
3343 proc_tty_register_driver(driver);
3344 driver->flags |= TTY_DRIVER_INSTALLED;
3348 for (i--; i >= 0; i--)
3349 tty_unregister_device(driver, i);
3351 mutex_lock(&tty_mutex);
3352 list_del(&driver->tty_drivers);
3353 mutex_unlock(&tty_mutex);
3356 unregister_chrdev_region(dev, driver->num);
3360 EXPORT_SYMBOL(tty_register_driver);
3363 * Called by a tty driver to unregister itself.
3365 int tty_unregister_driver(struct tty_driver *driver)
3369 if (driver->refcount)
3372 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3374 mutex_lock(&tty_mutex);
3375 list_del(&driver->tty_drivers);
3376 mutex_unlock(&tty_mutex);
3380 EXPORT_SYMBOL(tty_unregister_driver);
3382 dev_t tty_devnum(struct tty_struct *tty)
3384 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3386 EXPORT_SYMBOL(tty_devnum);
3388 void tty_default_fops(struct file_operations *fops)
3393 static char *tty_devnode(struct device *dev, umode_t *mode)
3397 if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
3398 dev->devt == MKDEV(TTYAUX_MAJOR, 2))
3403 static int __init tty_class_init(void)
3405 tty_class = class_create(THIS_MODULE, "tty");
3406 if (IS_ERR(tty_class))
3407 return PTR_ERR(tty_class);
3408 tty_class->devnode = tty_devnode;
3412 postcore_initcall(tty_class_init);
3414 /* 3/2004 jmc: why do these devices exist? */
3415 static struct cdev tty_cdev, console_cdev;
3417 static ssize_t show_cons_active(struct device *dev,
3418 struct device_attribute *attr, char *buf)
3420 struct console *cs[16];
3426 for_each_console(c) {
3431 if ((c->flags & CON_ENABLED) == 0)
3434 if (i >= ARRAY_SIZE(cs))
3438 int index = cs[i]->index;
3439 struct tty_driver *drv = cs[i]->device(cs[i], &index);
3441 /* don't resolve tty0 as some programs depend on it */
3442 if (drv && (cs[i]->index > 0 || drv->major != TTY_MAJOR))
3443 count += tty_line_name(drv, index, buf + count);
3445 count += sprintf(buf + count, "%s%d",
3446 cs[i]->name, cs[i]->index);
3448 count += sprintf(buf + count, "%c", i ? ' ':'\n');
3454 static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
3456 static struct attribute *cons_dev_attrs[] = {
3457 &dev_attr_active.attr,
3461 ATTRIBUTE_GROUPS(cons_dev);
3463 static struct device *consdev;
3465 void console_sysfs_notify(void)
3468 sysfs_notify(&consdev->kobj, NULL, "active");
3472 * Ok, now we can initialize the rest of the tty devices and can count
3473 * on memory allocations, interrupts etc..
3475 int __init tty_init(void)
3477 cdev_init(&tty_cdev, &tty_fops);
3478 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3479 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3480 panic("Couldn't register /dev/tty driver\n");
3481 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
3483 cdev_init(&console_cdev, &console_fops);
3484 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3485 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3486 panic("Couldn't register /dev/console driver\n");
3487 consdev = device_create_with_groups(tty_class, NULL,
3488 MKDEV(TTYAUX_MAJOR, 1), NULL,
3489 cons_dev_groups, "console");
3490 if (IS_ERR(consdev))
3494 vty_init(&console_fops);