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>
101 #include <linux/uaccess.h>
103 #include <linux/kbd_kern.h>
104 #include <linux/vt_kern.h>
105 #include <linux/selection.h>
107 #include <linux/kmod.h>
108 #include <linux/nsproxy.h>
110 #undef TTY_DEBUG_HANGUP
111 #ifdef TTY_DEBUG_HANGUP
112 # define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args)
114 # define tty_debug_hangup(tty, f, args...) do { } while (0)
117 #define TTY_PARANOIA_CHECK 1
118 #define CHECK_TTY_COUNT 1
120 struct ktermios tty_std_termios = { /* for the benefit of tty drivers */
121 .c_iflag = ICRNL | IXON,
122 .c_oflag = OPOST | ONLCR,
123 .c_cflag = B38400 | CS8 | CREAD | HUPCL,
124 .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
125 ECHOCTL | ECHOKE | IEXTEN,
129 /* .c_line = N_TTY, */
132 EXPORT_SYMBOL(tty_std_termios);
134 /* This list gets poked at by procfs and various bits of boot up code. This
135 could do with some rationalisation such as pulling the tty proc function
138 LIST_HEAD(tty_drivers); /* linked list of tty drivers */
140 /* Mutex to protect creating and releasing a tty */
141 DEFINE_MUTEX(tty_mutex);
143 static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
144 static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
145 ssize_t redirected_tty_write(struct file *, const char __user *,
147 static __poll_t tty_poll(struct file *, poll_table *);
148 static int tty_open(struct inode *, struct file *);
149 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
151 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
154 #define tty_compat_ioctl NULL
156 static int __tty_fasync(int fd, struct file *filp, int on);
157 static int tty_fasync(int fd, struct file *filp, int on);
158 static void release_tty(struct tty_struct *tty, int idx);
161 * free_tty_struct - free a disused tty
162 * @tty: tty struct to free
164 * Free the write buffers, tty queue and tty memory itself.
166 * Locking: none. Must be called after tty is definitely unused
169 static void free_tty_struct(struct tty_struct *tty)
171 tty_ldisc_deinit(tty);
172 put_device(tty->dev);
173 kfree(tty->write_buf);
174 tty->magic = 0xDEADDEAD;
178 static inline struct tty_struct *file_tty(struct file *file)
180 return ((struct tty_file_private *)file->private_data)->tty;
183 int tty_alloc_file(struct file *file)
185 struct tty_file_private *priv;
187 priv = kmalloc(sizeof(*priv), GFP_KERNEL);
191 file->private_data = priv;
196 /* Associate a new file with the tty structure */
197 void tty_add_file(struct tty_struct *tty, struct file *file)
199 struct tty_file_private *priv = file->private_data;
204 spin_lock(&tty->files_lock);
205 list_add(&priv->list, &tty->tty_files);
206 spin_unlock(&tty->files_lock);
210 * tty_free_file - free file->private_data
212 * This shall be used only for fail path handling when tty_add_file was not
215 void tty_free_file(struct file *file)
217 struct tty_file_private *priv = file->private_data;
219 file->private_data = NULL;
223 /* Delete file from its tty */
224 static void tty_del_file(struct file *file)
226 struct tty_file_private *priv = file->private_data;
227 struct tty_struct *tty = priv->tty;
229 spin_lock(&tty->files_lock);
230 list_del(&priv->list);
231 spin_unlock(&tty->files_lock);
236 * tty_name - return tty naming
237 * @tty: tty structure
239 * Convert a tty structure into a name. The name reflects the kernel
240 * naming policy and if udev is in use may not reflect user space
245 const char *tty_name(const struct tty_struct *tty)
247 if (!tty) /* Hmm. NULL pointer. That's fun. */
252 EXPORT_SYMBOL(tty_name);
254 const char *tty_driver_name(const struct tty_struct *tty)
256 if (!tty || !tty->driver)
258 return tty->driver->name;
261 static int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
264 #ifdef TTY_PARANOIA_CHECK
266 pr_warn("(%d:%d): %s: NULL tty\n",
267 imajor(inode), iminor(inode), routine);
270 if (tty->magic != TTY_MAGIC) {
271 pr_warn("(%d:%d): %s: bad magic number\n",
272 imajor(inode), iminor(inode), routine);
279 /* Caller must hold tty_lock */
280 static int check_tty_count(struct tty_struct *tty, const char *routine)
282 #ifdef CHECK_TTY_COUNT
284 int count = 0, kopen_count = 0;
286 spin_lock(&tty->files_lock);
287 list_for_each(p, &tty->tty_files) {
290 spin_unlock(&tty->files_lock);
291 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
292 tty->driver->subtype == PTY_TYPE_SLAVE &&
293 tty->link && tty->link->count)
295 if (tty_port_kopened(tty->port))
297 if (tty->count != (count + kopen_count)) {
298 tty_warn(tty, "%s: tty->count(%d) != (#fd's(%d) + #kopen's(%d))\n",
299 routine, tty->count, count, kopen_count);
300 return (count + kopen_count);
307 * get_tty_driver - find device of a tty
308 * @dev_t: device identifier
309 * @index: returns the index of the tty
311 * This routine returns a tty driver structure, given a device number
312 * and also passes back the index number.
314 * Locking: caller must hold tty_mutex
317 static struct tty_driver *get_tty_driver(dev_t device, int *index)
319 struct tty_driver *p;
321 list_for_each_entry(p, &tty_drivers, tty_drivers) {
322 dev_t base = MKDEV(p->major, p->minor_start);
323 if (device < base || device >= base + p->num)
325 *index = device - base;
326 return tty_driver_kref_get(p);
332 * tty_dev_name_to_number - return dev_t for device name
333 * @name: user space name of device under /dev
334 * @number: pointer to dev_t that this function will populate
336 * This function converts device names like ttyS0 or ttyUSB1 into dev_t
337 * like (4, 64) or (188, 1). If no corresponding driver is registered then
338 * the function returns -ENODEV.
340 * Locking: this acquires tty_mutex to protect the tty_drivers list from
341 * being modified while we are traversing it, and makes sure to
342 * release it before exiting.
344 int tty_dev_name_to_number(const char *name, dev_t *number)
346 struct tty_driver *p;
348 int index, prefix_length = 0;
351 for (str = name; *str && !isdigit(*str); str++)
357 ret = kstrtoint(str, 10, &index);
361 prefix_length = str - name;
362 mutex_lock(&tty_mutex);
364 list_for_each_entry(p, &tty_drivers, tty_drivers)
365 if (prefix_length == strlen(p->name) && strncmp(name,
366 p->name, prefix_length) == 0) {
367 if (index < p->num) {
368 *number = MKDEV(p->major, p->minor_start + index);
373 /* if here then driver wasn't found */
376 mutex_unlock(&tty_mutex);
379 EXPORT_SYMBOL_GPL(tty_dev_name_to_number);
381 #ifdef CONFIG_CONSOLE_POLL
384 * tty_find_polling_driver - find device of a polled tty
385 * @name: name string to match
386 * @line: pointer to resulting tty line nr
388 * This routine returns a tty driver structure, given a name
389 * and the condition that the tty driver is capable of polled
392 struct tty_driver *tty_find_polling_driver(char *name, int *line)
394 struct tty_driver *p, *res = NULL;
399 for (str = name; *str; str++)
400 if ((*str >= '0' && *str <= '9') || *str == ',')
406 tty_line = simple_strtoul(str, &str, 10);
408 mutex_lock(&tty_mutex);
409 /* Search through the tty devices to look for a match */
410 list_for_each_entry(p, &tty_drivers, tty_drivers) {
411 if (!len || strncmp(name, p->name, len) != 0)
419 if (tty_line >= 0 && tty_line < p->num && p->ops &&
420 p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) {
421 res = tty_driver_kref_get(p);
426 mutex_unlock(&tty_mutex);
430 EXPORT_SYMBOL_GPL(tty_find_polling_driver);
433 static ssize_t hung_up_tty_read(struct file *file, char __user *buf,
434 size_t count, loff_t *ppos)
439 static ssize_t hung_up_tty_write(struct file *file, const char __user *buf,
440 size_t count, loff_t *ppos)
445 /* No kernel lock held - none needed ;) */
446 static __poll_t hung_up_tty_poll(struct file *filp, poll_table *wait)
448 return EPOLLIN | EPOLLOUT | EPOLLERR | EPOLLHUP | EPOLLRDNORM | EPOLLWRNORM;
451 static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
454 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
457 static long hung_up_tty_compat_ioctl(struct file *file,
458 unsigned int cmd, unsigned long arg)
460 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
463 static int hung_up_tty_fasync(int fd, struct file *file, int on)
468 static void tty_show_fdinfo(struct seq_file *m, struct file *file)
470 struct tty_struct *tty = file_tty(file);
472 if (tty && tty->ops && tty->ops->show_fdinfo)
473 tty->ops->show_fdinfo(tty, m);
476 static const struct file_operations tty_fops = {
481 .unlocked_ioctl = tty_ioctl,
482 .compat_ioctl = tty_compat_ioctl,
484 .release = tty_release,
485 .fasync = tty_fasync,
486 .show_fdinfo = tty_show_fdinfo,
489 static const struct file_operations console_fops = {
492 .write = redirected_tty_write,
494 .unlocked_ioctl = tty_ioctl,
495 .compat_ioctl = tty_compat_ioctl,
497 .release = tty_release,
498 .fasync = tty_fasync,
501 static const struct file_operations hung_up_tty_fops = {
503 .read = hung_up_tty_read,
504 .write = hung_up_tty_write,
505 .poll = hung_up_tty_poll,
506 .unlocked_ioctl = hung_up_tty_ioctl,
507 .compat_ioctl = hung_up_tty_compat_ioctl,
508 .release = tty_release,
509 .fasync = hung_up_tty_fasync,
512 static DEFINE_SPINLOCK(redirect_lock);
513 static struct file *redirect;
515 extern void tty_sysctl_init(void);
518 * tty_wakeup - request more data
521 * Internal and external helper for wakeups of tty. This function
522 * informs the line discipline if present that the driver is ready
523 * to receive more output data.
526 void tty_wakeup(struct tty_struct *tty)
528 struct tty_ldisc *ld;
530 if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
531 ld = tty_ldisc_ref(tty);
533 if (ld->ops->write_wakeup)
534 ld->ops->write_wakeup(tty);
538 wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
541 EXPORT_SYMBOL_GPL(tty_wakeup);
544 * __tty_hangup - actual handler for hangup events
547 * This can be called by a "kworker" kernel thread. That is process
548 * synchronous but doesn't hold any locks, so we need to make sure we
549 * have the appropriate locks for what we're doing.
551 * The hangup event clears any pending redirections onto the hung up
552 * device. It ensures future writes will error and it does the needed
553 * line discipline hangup and signal delivery. The tty object itself
558 * redirect lock for undoing redirection
559 * file list lock for manipulating list of ttys
560 * tty_ldiscs_lock from called functions
561 * termios_rwsem resetting termios data
562 * tasklist_lock to walk task list for hangup event
563 * ->siglock to protect ->signal/->sighand
565 static void __tty_hangup(struct tty_struct *tty, int exit_session)
567 struct file *cons_filp = NULL;
568 struct file *filp, *f = NULL;
569 struct tty_file_private *priv;
570 int closecount = 0, n;
577 spin_lock(&redirect_lock);
578 if (redirect && file_tty(redirect) == tty) {
582 spin_unlock(&redirect_lock);
586 if (test_bit(TTY_HUPPED, &tty->flags)) {
592 * Some console devices aren't actually hung up for technical and
593 * historical reasons, which can lead to indefinite interruptible
594 * sleep in n_tty_read(). The following explicitly tells
595 * n_tty_read() to abort readers.
597 set_bit(TTY_HUPPING, &tty->flags);
599 /* inuse_filps is protected by the single tty lock,
600 this really needs to change if we want to flush the
601 workqueue with the lock held */
602 check_tty_count(tty, "tty_hangup");
604 spin_lock(&tty->files_lock);
605 /* This breaks for file handles being sent over AF_UNIX sockets ? */
606 list_for_each_entry(priv, &tty->tty_files, list) {
608 if (filp->f_op->write == redirected_tty_write)
610 if (filp->f_op->write != tty_write)
613 __tty_fasync(-1, filp, 0); /* can't block */
614 filp->f_op = &hung_up_tty_fops;
616 spin_unlock(&tty->files_lock);
618 refs = tty_signal_session_leader(tty, exit_session);
619 /* Account for the p->signal references we killed */
623 tty_ldisc_hangup(tty, cons_filp != NULL);
625 spin_lock_irq(&tty->ctrl_lock);
626 clear_bit(TTY_THROTTLED, &tty->flags);
627 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
628 put_pid(tty->session);
632 tty->ctrl_status = 0;
633 spin_unlock_irq(&tty->ctrl_lock);
636 * If one of the devices matches a console pointer, we
637 * cannot just call hangup() because that will cause
638 * tty->count and state->count to go out of sync.
639 * So we just call close() the right number of times.
643 for (n = 0; n < closecount; n++)
644 tty->ops->close(tty, cons_filp);
645 } else if (tty->ops->hangup)
646 tty->ops->hangup(tty);
648 * We don't want to have driver/ldisc interactions beyond the ones
649 * we did here. The driver layer expects no calls after ->hangup()
650 * from the ldisc side, which is now guaranteed.
652 set_bit(TTY_HUPPED, &tty->flags);
653 clear_bit(TTY_HUPPING, &tty->flags);
660 static void do_tty_hangup(struct work_struct *work)
662 struct tty_struct *tty =
663 container_of(work, struct tty_struct, hangup_work);
665 __tty_hangup(tty, 0);
669 * tty_hangup - trigger a hangup event
670 * @tty: tty to hangup
672 * A carrier loss (virtual or otherwise) has occurred on this like
673 * schedule a hangup sequence to run after this event.
676 void tty_hangup(struct tty_struct *tty)
678 tty_debug_hangup(tty, "hangup\n");
679 schedule_work(&tty->hangup_work);
682 EXPORT_SYMBOL(tty_hangup);
685 * tty_vhangup - process vhangup
686 * @tty: tty to hangup
688 * The user has asked via system call for the terminal to be hung up.
689 * We do this synchronously so that when the syscall returns the process
690 * is complete. That guarantee is necessary for security reasons.
693 void tty_vhangup(struct tty_struct *tty)
695 tty_debug_hangup(tty, "vhangup\n");
696 __tty_hangup(tty, 0);
699 EXPORT_SYMBOL(tty_vhangup);
703 * tty_vhangup_self - process vhangup for own ctty
705 * Perform a vhangup on the current controlling tty
708 void tty_vhangup_self(void)
710 struct tty_struct *tty;
712 tty = get_current_tty();
720 * tty_vhangup_session - hangup session leader exit
721 * @tty: tty to hangup
723 * The session leader is exiting and hanging up its controlling terminal.
724 * Every process in the foreground process group is signalled SIGHUP.
726 * We do this synchronously so that when the syscall returns the process
727 * is complete. That guarantee is necessary for security reasons.
730 void tty_vhangup_session(struct tty_struct *tty)
732 tty_debug_hangup(tty, "session hangup\n");
733 __tty_hangup(tty, 1);
737 * tty_hung_up_p - was tty hung up
738 * @filp: file pointer of tty
740 * Return true if the tty has been subject to a vhangup or a carrier
744 int tty_hung_up_p(struct file *filp)
746 return (filp && filp->f_op == &hung_up_tty_fops);
749 EXPORT_SYMBOL(tty_hung_up_p);
752 * stop_tty - propagate flow control
755 * Perform flow control to the driver. May be called
756 * on an already stopped device and will not re-call the driver
759 * This functionality is used by both the line disciplines for
760 * halting incoming flow and by the driver. It may therefore be
761 * called from any context, may be under the tty atomic_write_lock
768 void __stop_tty(struct tty_struct *tty)
777 void stop_tty(struct tty_struct *tty)
781 spin_lock_irqsave(&tty->flow_lock, flags);
783 spin_unlock_irqrestore(&tty->flow_lock, flags);
785 EXPORT_SYMBOL(stop_tty);
788 * start_tty - propagate flow control
791 * Start a tty that has been stopped if at all possible. If this
792 * tty was previous stopped and is now being started, the driver
793 * start method is invoked and the line discipline woken.
799 void __start_tty(struct tty_struct *tty)
801 if (!tty->stopped || tty->flow_stopped)
805 tty->ops->start(tty);
809 void start_tty(struct tty_struct *tty)
813 spin_lock_irqsave(&tty->flow_lock, flags);
815 spin_unlock_irqrestore(&tty->flow_lock, flags);
817 EXPORT_SYMBOL(start_tty);
819 static void tty_update_time(struct timespec64 *time)
821 time64_t sec = ktime_get_real_seconds();
824 * We only care if the two values differ in anything other than the
825 * lower three bits (i.e every 8 seconds). If so, then we can update
826 * the time of the tty device, otherwise it could be construded as a
827 * security leak to let userspace know the exact timing of the tty.
829 if ((sec ^ time->tv_sec) & ~7)
834 * tty_read - read method for tty device files
835 * @file: pointer to tty file
837 * @count: size of user buffer
840 * Perform the read system call function on this terminal device. Checks
841 * for hung up devices before calling the line discipline method.
844 * Locks the line discipline internally while needed. Multiple
845 * read calls may be outstanding in parallel.
848 static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
852 struct inode *inode = file_inode(file);
853 struct tty_struct *tty = file_tty(file);
854 struct tty_ldisc *ld;
856 if (tty_paranoia_check(tty, inode, "tty_read"))
858 if (!tty || tty_io_error(tty))
861 /* We want to wait for the line discipline to sort out in this
863 ld = tty_ldisc_ref_wait(tty);
865 return hung_up_tty_read(file, buf, count, ppos);
867 i = ld->ops->read(tty, file, buf, count);
873 tty_update_time(&inode->i_atime);
878 void tty_write_unlock(struct tty_struct *tty)
880 mutex_unlock(&tty->atomic_write_lock);
881 wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
884 int tty_write_lock(struct tty_struct *tty, int ndelay)
886 if (!mutex_trylock(&tty->atomic_write_lock)) {
889 if (mutex_lock_interruptible(&tty->atomic_write_lock))
896 * Split writes up in sane blocksizes to avoid
897 * denial-of-service type attacks
899 static inline ssize_t do_tty_write(
900 ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
901 struct tty_struct *tty,
903 const char __user *buf,
906 ssize_t ret, written = 0;
909 ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
914 * We chunk up writes into a temporary buffer. This
915 * simplifies low-level drivers immensely, since they
916 * don't have locking issues and user mode accesses.
918 * But if TTY_NO_WRITE_SPLIT is set, we should use a
921 * The default chunk-size is 2kB, because the NTTY
922 * layer has problems with bigger chunks. It will
923 * claim to be able to handle more characters than
926 * FIXME: This can probably go away now except that 64K chunks
927 * are too likely to fail unless switched to vmalloc...
930 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
935 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
936 if (tty->write_cnt < chunk) {
937 unsigned char *buf_chunk;
942 buf_chunk = kmalloc(chunk, GFP_KERNEL);
947 kfree(tty->write_buf);
948 tty->write_cnt = chunk;
949 tty->write_buf = buf_chunk;
952 /* Do the write .. */
958 if (copy_from_user(tty->write_buf, buf, size))
960 ret = write(tty, file, tty->write_buf, size);
969 if (signal_pending(current))
974 tty_update_time(&file_inode(file)->i_mtime);
978 tty_write_unlock(tty);
983 * tty_write_message - write a message to a certain tty, not just the console.
984 * @tty: the destination tty_struct
985 * @msg: the message to write
987 * This is used for messages that need to be redirected to a specific tty.
988 * We don't put it into the syslog queue right now maybe in the future if
991 * We must still hold the BTM and test the CLOSING flag for the moment.
994 void tty_write_message(struct tty_struct *tty, char *msg)
997 mutex_lock(&tty->atomic_write_lock);
999 if (tty->ops->write && tty->count > 0)
1000 tty->ops->write(tty, msg, strlen(msg));
1002 tty_write_unlock(tty);
1009 * tty_write - write method for tty device file
1010 * @file: tty file pointer
1011 * @buf: user data to write
1012 * @count: bytes to write
1015 * Write data to a tty device via the line discipline.
1018 * Locks the line discipline as required
1019 * Writes to the tty driver are serialized by the atomic_write_lock
1020 * and are then processed in chunks to the device. The line discipline
1021 * write method will not be invoked in parallel for each device.
1024 static ssize_t tty_write(struct file *file, const char __user *buf,
1025 size_t count, loff_t *ppos)
1027 struct tty_struct *tty = file_tty(file);
1028 struct tty_ldisc *ld;
1031 if (tty_paranoia_check(tty, file_inode(file), "tty_write"))
1033 if (!tty || !tty->ops->write || tty_io_error(tty))
1035 /* Short term debug to catch buggy drivers */
1036 if (tty->ops->write_room == NULL)
1037 tty_err(tty, "missing write_room method\n");
1038 ld = tty_ldisc_ref_wait(tty);
1040 return hung_up_tty_write(file, buf, count, ppos);
1041 if (!ld->ops->write)
1044 ret = do_tty_write(ld->ops->write, tty, file, buf, count);
1045 tty_ldisc_deref(ld);
1049 ssize_t redirected_tty_write(struct file *file, const char __user *buf,
1050 size_t count, loff_t *ppos)
1052 struct file *p = NULL;
1054 spin_lock(&redirect_lock);
1056 p = get_file(redirect);
1057 spin_unlock(&redirect_lock);
1061 res = vfs_write(p, buf, count, &p->f_pos);
1065 return tty_write(file, buf, count, ppos);
1069 * tty_send_xchar - send priority character
1071 * Send a high priority character to the tty even if stopped
1073 * Locking: none for xchar method, write ordering for write method.
1076 int tty_send_xchar(struct tty_struct *tty, char ch)
1078 int was_stopped = tty->stopped;
1080 if (tty->ops->send_xchar) {
1081 down_read(&tty->termios_rwsem);
1082 tty->ops->send_xchar(tty, ch);
1083 up_read(&tty->termios_rwsem);
1087 if (tty_write_lock(tty, 0) < 0)
1088 return -ERESTARTSYS;
1090 down_read(&tty->termios_rwsem);
1093 tty->ops->write(tty, &ch, 1);
1096 up_read(&tty->termios_rwsem);
1097 tty_write_unlock(tty);
1101 static char ptychar[] = "pqrstuvwxyzabcde";
1104 * pty_line_name - generate name for a pty
1105 * @driver: the tty driver in use
1106 * @index: the minor number
1107 * @p: output buffer of at least 6 bytes
1109 * Generate a name from a driver reference and write it to the output
1114 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1116 int i = index + driver->name_base;
1117 /* ->name is initialized to "ttyp", but "tty" is expected */
1118 sprintf(p, "%s%c%x",
1119 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1120 ptychar[i >> 4 & 0xf], i & 0xf);
1124 * tty_line_name - generate name for a tty
1125 * @driver: the tty driver in use
1126 * @index: the minor number
1127 * @p: output buffer of at least 7 bytes
1129 * Generate a name from a driver reference and write it to the output
1134 static ssize_t tty_line_name(struct tty_driver *driver, int index, char *p)
1136 if (driver->flags & TTY_DRIVER_UNNUMBERED_NODE)
1137 return sprintf(p, "%s", driver->name);
1139 return sprintf(p, "%s%d", driver->name,
1140 index + driver->name_base);
1144 * tty_driver_lookup_tty() - find an existing tty, if any
1145 * @driver: the driver for the tty
1146 * @idx: the minor number
1148 * Return the tty, if found. If not found, return NULL or ERR_PTR() if the
1149 * driver lookup() method returns an error.
1151 * Locking: tty_mutex must be held. If the tty is found, bump the tty kref.
1153 static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
1154 struct file *file, int idx)
1156 struct tty_struct *tty;
1158 if (driver->ops->lookup) {
1160 tty = ERR_PTR(-EIO);
1162 tty = driver->ops->lookup(driver, file, idx);
1164 if (idx >= driver->num)
1165 return ERR_PTR(-EINVAL);
1166 tty = driver->ttys[idx];
1174 * tty_init_termios - helper for termios setup
1175 * @tty: the tty to set up
1177 * Initialise the termios structures for this tty. Thus runs under
1178 * the tty_mutex currently so we can be relaxed about ordering.
1181 void tty_init_termios(struct tty_struct *tty)
1183 struct ktermios *tp;
1184 int idx = tty->index;
1186 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1187 tty->termios = tty->driver->init_termios;
1189 /* Check for lazy saved data */
1190 tp = tty->driver->termios[idx];
1193 tty->termios.c_line = tty->driver->init_termios.c_line;
1195 tty->termios = tty->driver->init_termios;
1197 /* Compatibility until drivers always set this */
1198 tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
1199 tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
1201 EXPORT_SYMBOL_GPL(tty_init_termios);
1203 int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty)
1205 tty_init_termios(tty);
1206 tty_driver_kref_get(driver);
1208 driver->ttys[tty->index] = tty;
1211 EXPORT_SYMBOL_GPL(tty_standard_install);
1214 * tty_driver_install_tty() - install a tty entry in the driver
1215 * @driver: the driver for the tty
1218 * Install a tty object into the driver tables. The tty->index field
1219 * will be set by the time this is called. This method is responsible
1220 * for ensuring any need additional structures are allocated and
1223 * Locking: tty_mutex for now
1225 static int tty_driver_install_tty(struct tty_driver *driver,
1226 struct tty_struct *tty)
1228 return driver->ops->install ? driver->ops->install(driver, tty) :
1229 tty_standard_install(driver, tty);
1233 * tty_driver_remove_tty() - remove a tty from the driver tables
1234 * @driver: the driver for the tty
1235 * @idx: the minor number
1237 * Remvoe a tty object from the driver tables. The tty->index field
1238 * will be set by the time this is called.
1240 * Locking: tty_mutex for now
1242 static void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *tty)
1244 if (driver->ops->remove)
1245 driver->ops->remove(driver, tty);
1247 driver->ttys[tty->index] = NULL;
1251 * tty_reopen() - fast re-open of an open tty
1252 * @tty - the tty to open
1254 * Return 0 on success, -errno on error.
1255 * Re-opens on master ptys are not allowed and return -EIO.
1257 * Locking: Caller must hold tty_lock
1259 static int tty_reopen(struct tty_struct *tty)
1261 struct tty_driver *driver = tty->driver;
1262 struct tty_ldisc *ld;
1265 if (driver->type == TTY_DRIVER_TYPE_PTY &&
1266 driver->subtype == PTY_TYPE_MASTER)
1272 if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
1275 ld = tty_ldisc_ref_wait(tty);
1277 tty_ldisc_deref(ld);
1279 retval = tty_ldisc_lock(tty, 5 * HZ);
1284 retval = tty_ldisc_reinit(tty, tty->termios.c_line);
1285 tty_ldisc_unlock(tty);
1295 * tty_init_dev - initialise a tty device
1296 * @driver: tty driver we are opening a device on
1297 * @idx: device index
1298 * @ret_tty: returned tty structure
1300 * Prepare a tty device. This may not be a "new" clean device but
1301 * could also be an active device. The pty drivers require special
1302 * handling because of this.
1305 * The function is called under the tty_mutex, which
1306 * protects us from the tty struct or driver itself going away.
1308 * On exit the tty device has the line discipline attached and
1309 * a reference count of 1. If a pair was created for pty/tty use
1310 * and the other was a pty master then it too has a reference count of 1.
1312 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1313 * failed open. The new code protects the open with a mutex, so it's
1314 * really quite straightforward. The mutex locking can probably be
1315 * relaxed for the (most common) case of reopening a tty.
1318 struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
1320 struct tty_struct *tty;
1324 * First time open is complex, especially for PTY devices.
1325 * This code guarantees that either everything succeeds and the
1326 * TTY is ready for operation, or else the table slots are vacated
1327 * and the allocated memory released. (Except that the termios
1331 if (!try_module_get(driver->owner))
1332 return ERR_PTR(-ENODEV);
1334 tty = alloc_tty_struct(driver, idx);
1337 goto err_module_put;
1341 retval = tty_driver_install_tty(driver, tty);
1346 tty->port = driver->ports[idx];
1348 WARN_RATELIMIT(!tty->port,
1349 "%s: %s driver does not set tty->port. This will crash the kernel later. Fix the driver!\n",
1350 __func__, tty->driver->name);
1352 retval = tty_ldisc_lock(tty, 5 * HZ);
1354 goto err_release_lock;
1355 tty->port->itty = tty;
1358 * Structures all installed ... call the ldisc open routines.
1359 * If we fail here just call release_tty to clean up. No need
1360 * to decrement the use counts, as release_tty doesn't care.
1362 retval = tty_ldisc_setup(tty, tty->link);
1364 goto err_release_tty;
1365 tty_ldisc_unlock(tty);
1366 /* Return the tty locked so that it cannot vanish under the caller */
1371 free_tty_struct(tty);
1373 module_put(driver->owner);
1374 return ERR_PTR(retval);
1376 /* call the tty release_tty routine to clean out this slot */
1378 tty_ldisc_unlock(tty);
1379 tty_info_ratelimited(tty, "ldisc open failed (%d), clearing slot %d\n",
1383 release_tty(tty, idx);
1384 return ERR_PTR(retval);
1388 * tty_save_termios() - save tty termios data in driver table
1389 * @tty: tty whose termios data to save
1391 * Locking: Caller guarantees serialisation with tty_init_termios().
1393 void tty_save_termios(struct tty_struct *tty)
1395 struct ktermios *tp;
1396 int idx = tty->index;
1398 /* If the port is going to reset then it has no termios to save */
1399 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1402 /* Stash the termios data */
1403 tp = tty->driver->termios[idx];
1405 tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
1408 tty->driver->termios[idx] = tp;
1412 EXPORT_SYMBOL_GPL(tty_save_termios);
1415 * tty_flush_works - flush all works of a tty/pty pair
1416 * @tty: tty device to flush works for (or either end of a pty pair)
1418 * Sync flush all works belonging to @tty (and the 'other' tty).
1420 static void tty_flush_works(struct tty_struct *tty)
1422 flush_work(&tty->SAK_work);
1423 flush_work(&tty->hangup_work);
1425 flush_work(&tty->link->SAK_work);
1426 flush_work(&tty->link->hangup_work);
1431 * release_one_tty - release tty structure memory
1432 * @kref: kref of tty we are obliterating
1434 * Releases memory associated with a tty structure, and clears out the
1435 * driver table slots. This function is called when a device is no longer
1436 * in use. It also gets called when setup of a device fails.
1439 * takes the file list lock internally when working on the list
1440 * of ttys that the driver keeps.
1442 * This method gets called from a work queue so that the driver private
1443 * cleanup ops can sleep (needed for USB at least)
1445 static void release_one_tty(struct work_struct *work)
1447 struct tty_struct *tty =
1448 container_of(work, struct tty_struct, hangup_work);
1449 struct tty_driver *driver = tty->driver;
1450 struct module *owner = driver->owner;
1452 if (tty->ops->cleanup)
1453 tty->ops->cleanup(tty);
1456 tty_driver_kref_put(driver);
1459 spin_lock(&tty->files_lock);
1460 list_del_init(&tty->tty_files);
1461 spin_unlock(&tty->files_lock);
1464 put_pid(tty->session);
1465 free_tty_struct(tty);
1468 static void queue_release_one_tty(struct kref *kref)
1470 struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1472 /* The hangup queue is now free so we can reuse it rather than
1473 waste a chunk of memory for each port */
1474 INIT_WORK(&tty->hangup_work, release_one_tty);
1475 schedule_work(&tty->hangup_work);
1479 * tty_kref_put - release a tty kref
1482 * Release a reference to a tty device and if need be let the kref
1483 * layer destruct the object for us
1486 void tty_kref_put(struct tty_struct *tty)
1489 kref_put(&tty->kref, queue_release_one_tty);
1491 EXPORT_SYMBOL(tty_kref_put);
1494 * release_tty - release tty structure memory
1496 * Release both @tty and a possible linked partner (think pty pair),
1497 * and decrement the refcount of the backing module.
1501 * takes the file list lock internally when working on the list
1502 * of ttys that the driver keeps.
1505 static void release_tty(struct tty_struct *tty, int idx)
1507 /* This should always be true but check for the moment */
1508 WARN_ON(tty->index != idx);
1509 WARN_ON(!mutex_is_locked(&tty_mutex));
1510 if (tty->ops->shutdown)
1511 tty->ops->shutdown(tty);
1512 tty_save_termios(tty);
1513 tty_driver_remove_tty(tty->driver, tty);
1514 tty->port->itty = NULL;
1516 tty->link->port->itty = NULL;
1517 tty_buffer_cancel_work(tty->port);
1519 tty_buffer_cancel_work(tty->link->port);
1521 tty_kref_put(tty->link);
1526 * tty_release_checks - check a tty before real release
1527 * @tty: tty to check
1528 * @o_tty: link of @tty (if any)
1529 * @idx: index of the tty
1531 * Performs some paranoid checking before true release of the @tty.
1532 * This is a no-op unless TTY_PARANOIA_CHECK is defined.
1534 static int tty_release_checks(struct tty_struct *tty, int idx)
1536 #ifdef TTY_PARANOIA_CHECK
1537 if (idx < 0 || idx >= tty->driver->num) {
1538 tty_debug(tty, "bad idx %d\n", idx);
1542 /* not much to check for devpts */
1543 if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)
1546 if (tty != tty->driver->ttys[idx]) {
1547 tty_debug(tty, "bad driver table[%d] = %p\n",
1548 idx, tty->driver->ttys[idx]);
1551 if (tty->driver->other) {
1552 struct tty_struct *o_tty = tty->link;
1554 if (o_tty != tty->driver->other->ttys[idx]) {
1555 tty_debug(tty, "bad other table[%d] = %p\n",
1556 idx, tty->driver->other->ttys[idx]);
1559 if (o_tty->link != tty) {
1560 tty_debug(tty, "bad link = %p\n", o_tty->link);
1569 * tty_kclose - closes tty opened by tty_kopen
1572 * Performs the final steps to release and free a tty device. It is the
1573 * same as tty_release_struct except that it also resets TTY_PORT_KOPENED
1574 * flag on tty->port.
1576 void tty_kclose(struct tty_struct *tty)
1579 * Ask the line discipline code to release its structures
1581 tty_ldisc_release(tty);
1583 /* Wait for pending work before tty destruction commmences */
1584 tty_flush_works(tty);
1586 tty_debug_hangup(tty, "freeing structure\n");
1588 * The release_tty function takes care of the details of clearing
1589 * the slots and preserving the termios structure. The tty_unlock_pair
1590 * should be safe as we keep a kref while the tty is locked (so the
1591 * unlock never unlocks a freed tty).
1593 mutex_lock(&tty_mutex);
1594 tty_port_set_kopened(tty->port, 0);
1595 release_tty(tty, tty->index);
1596 mutex_unlock(&tty_mutex);
1598 EXPORT_SYMBOL_GPL(tty_kclose);
1601 * tty_release_struct - release a tty struct
1603 * @idx: index of the tty
1605 * Performs the final steps to release and free a tty device. It is
1606 * roughly the reverse of tty_init_dev.
1608 void tty_release_struct(struct tty_struct *tty, int idx)
1611 * Ask the line discipline code to release its structures
1613 tty_ldisc_release(tty);
1615 /* Wait for pending work before tty destruction commmences */
1616 tty_flush_works(tty);
1618 tty_debug_hangup(tty, "freeing structure\n");
1620 * The release_tty function takes care of the details of clearing
1621 * the slots and preserving the termios structure. The tty_unlock_pair
1622 * should be safe as we keep a kref while the tty is locked (so the
1623 * unlock never unlocks a freed tty).
1625 mutex_lock(&tty_mutex);
1626 release_tty(tty, idx);
1627 mutex_unlock(&tty_mutex);
1629 EXPORT_SYMBOL_GPL(tty_release_struct);
1632 * tty_release - vfs callback for close
1633 * @inode: inode of tty
1634 * @filp: file pointer for handle to tty
1636 * Called the last time each file handle is closed that references
1637 * this tty. There may however be several such references.
1640 * Takes bkl. See tty_release_dev
1642 * Even releasing the tty structures is a tricky business.. We have
1643 * to be very careful that the structures are all released at the
1644 * same time, as interrupts might otherwise get the wrong pointers.
1646 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1647 * lead to double frees or releasing memory still in use.
1650 int tty_release(struct inode *inode, struct file *filp)
1652 struct tty_struct *tty = file_tty(filp);
1653 struct tty_struct *o_tty = NULL;
1654 int do_sleep, final;
1659 if (tty_paranoia_check(tty, inode, __func__))
1663 check_tty_count(tty, __func__);
1665 __tty_fasync(-1, filp, 0);
1668 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1669 tty->driver->subtype == PTY_TYPE_MASTER)
1672 if (tty_release_checks(tty, idx)) {
1677 tty_debug_hangup(tty, "releasing (count=%d)\n", tty->count);
1679 if (tty->ops->close)
1680 tty->ops->close(tty, filp);
1682 /* If tty is pty master, lock the slave pty (stable lock order) */
1683 tty_lock_slave(o_tty);
1686 * Sanity check: if tty->count is going to zero, there shouldn't be
1687 * any waiters on tty->read_wait or tty->write_wait. We test the
1688 * wait queues and kick everyone out _before_ actually starting to
1689 * close. This ensures that we won't block while releasing the tty
1692 * The test for the o_tty closing is necessary, since the master and
1693 * slave sides may close in any order. If the slave side closes out
1694 * first, its count will be one, since the master side holds an open.
1695 * Thus this test wouldn't be triggered at the time the slave closed,
1701 if (tty->count <= 1) {
1702 if (waitqueue_active(&tty->read_wait)) {
1703 wake_up_poll(&tty->read_wait, EPOLLIN);
1706 if (waitqueue_active(&tty->write_wait)) {
1707 wake_up_poll(&tty->write_wait, EPOLLOUT);
1711 if (o_tty && o_tty->count <= 1) {
1712 if (waitqueue_active(&o_tty->read_wait)) {
1713 wake_up_poll(&o_tty->read_wait, EPOLLIN);
1716 if (waitqueue_active(&o_tty->write_wait)) {
1717 wake_up_poll(&o_tty->write_wait, EPOLLOUT);
1726 tty_warn(tty, "read/write wait queue active!\n");
1728 schedule_timeout_killable(timeout);
1729 if (timeout < 120 * HZ)
1730 timeout = 2 * timeout + 1;
1732 timeout = MAX_SCHEDULE_TIMEOUT;
1736 if (--o_tty->count < 0) {
1737 tty_warn(tty, "bad slave count (%d)\n", o_tty->count);
1741 if (--tty->count < 0) {
1742 tty_warn(tty, "bad tty->count (%d)\n", tty->count);
1747 * We've decremented tty->count, so we need to remove this file
1748 * descriptor off the tty->tty_files list; this serves two
1750 * - check_tty_count sees the correct number of file descriptors
1751 * associated with this tty.
1752 * - do_tty_hangup no longer sees this file descriptor as
1753 * something that needs to be handled for hangups.
1758 * Perform some housekeeping before deciding whether to return.
1760 * If _either_ side is closing, make sure there aren't any
1761 * processes that still think tty or o_tty is their controlling
1765 read_lock(&tasklist_lock);
1766 session_clear_tty(tty->session);
1768 session_clear_tty(o_tty->session);
1769 read_unlock(&tasklist_lock);
1772 /* check whether both sides are closing ... */
1773 final = !tty->count && !(o_tty && o_tty->count);
1775 tty_unlock_slave(o_tty);
1778 /* At this point, the tty->count == 0 should ensure a dead tty
1779 cannot be re-opened by a racing opener */
1784 tty_debug_hangup(tty, "final close\n");
1786 tty_release_struct(tty, idx);
1791 * tty_open_current_tty - get locked tty of current task
1792 * @device: device number
1793 * @filp: file pointer to tty
1794 * @return: locked tty of the current task iff @device is /dev/tty
1796 * Performs a re-open of the current task's controlling tty.
1798 * We cannot return driver and index like for the other nodes because
1799 * devpts will not work then. It expects inodes to be from devpts FS.
1801 static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
1803 struct tty_struct *tty;
1806 if (device != MKDEV(TTYAUX_MAJOR, 0))
1809 tty = get_current_tty();
1811 return ERR_PTR(-ENXIO);
1813 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1816 tty_kref_put(tty); /* safe to drop the kref now */
1818 retval = tty_reopen(tty);
1821 tty = ERR_PTR(retval);
1827 * tty_lookup_driver - lookup a tty driver for a given device file
1828 * @device: device number
1829 * @filp: file pointer to tty
1830 * @index: index for the device in the @return driver
1831 * @return: driver for this inode (with increased refcount)
1833 * If @return is not erroneous, the caller is responsible to decrement the
1834 * refcount by tty_driver_kref_put.
1836 * Locking: tty_mutex protects get_tty_driver
1838 static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
1841 struct tty_driver *driver;
1845 case MKDEV(TTY_MAJOR, 0): {
1846 extern struct tty_driver *console_driver;
1847 driver = tty_driver_kref_get(console_driver);
1848 *index = fg_console;
1852 case MKDEV(TTYAUX_MAJOR, 1): {
1853 struct tty_driver *console_driver = console_device(index);
1854 if (console_driver) {
1855 driver = tty_driver_kref_get(console_driver);
1856 if (driver && filp) {
1857 /* Don't let /dev/console block */
1858 filp->f_flags |= O_NONBLOCK;
1862 return ERR_PTR(-ENODEV);
1865 driver = get_tty_driver(device, index);
1867 return ERR_PTR(-ENODEV);
1874 * tty_kopen - open a tty device for kernel
1875 * @device: dev_t of device to open
1877 * Opens tty exclusively for kernel. Performs the driver lookup,
1878 * makes sure it's not already opened and performs the first-time
1879 * tty initialization.
1881 * Returns the locked initialized &tty_struct
1883 * Claims the global tty_mutex to serialize:
1884 * - concurrent first-time tty initialization
1885 * - concurrent tty driver removal w/ lookup
1886 * - concurrent tty removal from driver table
1888 struct tty_struct *tty_kopen(dev_t device)
1890 struct tty_struct *tty;
1891 struct tty_driver *driver = NULL;
1894 mutex_lock(&tty_mutex);
1895 driver = tty_lookup_driver(device, NULL, &index);
1896 if (IS_ERR(driver)) {
1897 mutex_unlock(&tty_mutex);
1898 return ERR_CAST(driver);
1901 /* check whether we're reopening an existing tty */
1902 tty = tty_driver_lookup_tty(driver, NULL, index);
1907 /* drop kref from tty_driver_lookup_tty() */
1909 tty = ERR_PTR(-EBUSY);
1910 } else { /* tty_init_dev returns tty with the tty_lock held */
1911 tty = tty_init_dev(driver, index);
1914 tty_port_set_kopened(tty->port, 1);
1917 mutex_unlock(&tty_mutex);
1918 tty_driver_kref_put(driver);
1921 EXPORT_SYMBOL_GPL(tty_kopen);
1924 * tty_open_by_driver - open a tty device
1925 * @device: dev_t of device to open
1926 * @inode: inode of device file
1927 * @filp: file pointer to tty
1929 * Performs the driver lookup, checks for a reopen, or otherwise
1930 * performs the first-time tty initialization.
1932 * Returns the locked initialized or re-opened &tty_struct
1934 * Claims the global tty_mutex to serialize:
1935 * - concurrent first-time tty initialization
1936 * - concurrent tty driver removal w/ lookup
1937 * - concurrent tty removal from driver table
1939 static struct tty_struct *tty_open_by_driver(dev_t device, struct inode *inode,
1942 struct tty_struct *tty;
1943 struct tty_driver *driver = NULL;
1947 mutex_lock(&tty_mutex);
1948 driver = tty_lookup_driver(device, filp, &index);
1949 if (IS_ERR(driver)) {
1950 mutex_unlock(&tty_mutex);
1951 return ERR_CAST(driver);
1954 /* check whether we're reopening an existing tty */
1955 tty = tty_driver_lookup_tty(driver, filp, index);
1957 mutex_unlock(&tty_mutex);
1962 if (tty_port_kopened(tty->port)) {
1964 mutex_unlock(&tty_mutex);
1965 tty = ERR_PTR(-EBUSY);
1968 mutex_unlock(&tty_mutex);
1969 retval = tty_lock_interruptible(tty);
1970 tty_kref_put(tty); /* drop kref from tty_driver_lookup_tty() */
1972 if (retval == -EINTR)
1973 retval = -ERESTARTSYS;
1974 tty = ERR_PTR(retval);
1977 retval = tty_reopen(tty);
1980 tty = ERR_PTR(retval);
1982 } else { /* Returns with the tty_lock held for now */
1983 tty = tty_init_dev(driver, index);
1984 mutex_unlock(&tty_mutex);
1987 tty_driver_kref_put(driver);
1992 * tty_open - open a tty device
1993 * @inode: inode of device file
1994 * @filp: file pointer to tty
1996 * tty_open and tty_release keep up the tty count that contains the
1997 * number of opens done on a tty. We cannot use the inode-count, as
1998 * different inodes might point to the same tty.
2000 * Open-counting is needed for pty masters, as well as for keeping
2001 * track of serial lines: DTR is dropped when the last close happens.
2002 * (This is not done solely through tty->count, now. - Ted 1/27/92)
2004 * The termios state of a pty is reset on first open so that
2005 * settings don't persist across reuse.
2007 * Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.
2008 * tty->count should protect the rest.
2009 * ->siglock protects ->signal/->sighand
2011 * Note: the tty_unlock/lock cases without a ref are only safe due to
2015 static int tty_open(struct inode *inode, struct file *filp)
2017 struct tty_struct *tty;
2019 dev_t device = inode->i_rdev;
2020 unsigned saved_flags = filp->f_flags;
2022 nonseekable_open(inode, filp);
2025 retval = tty_alloc_file(filp);
2029 tty = tty_open_current_tty(device, filp);
2031 tty = tty_open_by_driver(device, inode, filp);
2034 tty_free_file(filp);
2035 retval = PTR_ERR(tty);
2036 if (retval != -EAGAIN || signal_pending(current))
2042 tty_add_file(tty, filp);
2044 check_tty_count(tty, __func__);
2045 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
2048 retval = tty->ops->open(tty, filp);
2051 filp->f_flags = saved_flags;
2054 tty_debug_hangup(tty, "open error %d, releasing\n", retval);
2056 tty_unlock(tty); /* need to call tty_release without BTM */
2057 tty_release(inode, filp);
2058 if (retval != -ERESTARTSYS)
2061 if (signal_pending(current))
2066 * Need to reset f_op in case a hangup happened.
2068 if (tty_hung_up_p(filp))
2069 filp->f_op = &tty_fops;
2072 clear_bit(TTY_HUPPED, &tty->flags);
2074 noctty = (filp->f_flags & O_NOCTTY) ||
2075 (IS_ENABLED(CONFIG_VT) && device == MKDEV(TTY_MAJOR, 0)) ||
2076 device == MKDEV(TTYAUX_MAJOR, 1) ||
2077 (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2078 tty->driver->subtype == PTY_TYPE_MASTER);
2080 tty_open_proc_set_tty(filp, tty);
2088 * tty_poll - check tty status
2089 * @filp: file being polled
2090 * @wait: poll wait structures to update
2092 * Call the line discipline polling method to obtain the poll
2093 * status of the device.
2095 * Locking: locks called line discipline but ldisc poll method
2096 * may be re-entered freely by other callers.
2099 static __poll_t tty_poll(struct file *filp, poll_table *wait)
2101 struct tty_struct *tty = file_tty(filp);
2102 struct tty_ldisc *ld;
2105 if (tty_paranoia_check(tty, file_inode(filp), "tty_poll"))
2108 ld = tty_ldisc_ref_wait(tty);
2110 return hung_up_tty_poll(filp, wait);
2112 ret = ld->ops->poll(tty, filp, wait);
2113 tty_ldisc_deref(ld);
2117 static int __tty_fasync(int fd, struct file *filp, int on)
2119 struct tty_struct *tty = file_tty(filp);
2120 unsigned long flags;
2123 if (tty_paranoia_check(tty, file_inode(filp), "tty_fasync"))
2126 retval = fasync_helper(fd, filp, on, &tty->fasync);
2134 spin_lock_irqsave(&tty->ctrl_lock, flags);
2137 type = PIDTYPE_PGID;
2139 pid = task_pid(current);
2140 type = PIDTYPE_TGID;
2143 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2144 __f_setown(filp, pid, type, 0);
2152 static int tty_fasync(int fd, struct file *filp, int on)
2154 struct tty_struct *tty = file_tty(filp);
2155 int retval = -ENOTTY;
2158 if (!tty_hung_up_p(filp))
2159 retval = __tty_fasync(fd, filp, on);
2166 * tiocsti - fake input character
2167 * @tty: tty to fake input into
2168 * @p: pointer to character
2170 * Fake input to a tty device. Does the necessary locking and
2173 * FIXME: does not honour flow control ??
2176 * Called functions take tty_ldiscs_lock
2177 * current->signal->tty check is safe without locks
2180 static int tiocsti(struct tty_struct *tty, char __user *p)
2183 struct tty_ldisc *ld;
2185 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2187 if (get_user(ch, p))
2189 tty_audit_tiocsti(tty, ch);
2190 ld = tty_ldisc_ref_wait(tty);
2193 tty_buffer_lock_exclusive(tty->port);
2194 if (ld->ops->receive_buf)
2195 ld->ops->receive_buf(tty, &ch, &mbz, 1);
2196 tty_buffer_unlock_exclusive(tty->port);
2197 tty_ldisc_deref(ld);
2202 * tiocgwinsz - implement window query ioctl
2204 * @arg: user buffer for result
2206 * Copies the kernel idea of the window size into the user buffer.
2208 * Locking: tty->winsize_mutex is taken to ensure the winsize data
2212 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2216 mutex_lock(&tty->winsize_mutex);
2217 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2218 mutex_unlock(&tty->winsize_mutex);
2220 return err ? -EFAULT: 0;
2224 * tty_do_resize - resize event
2225 * @tty: tty being resized
2226 * @rows: rows (character)
2227 * @cols: cols (character)
2229 * Update the termios variables and send the necessary signals to
2230 * peform a terminal resize correctly
2233 int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
2238 mutex_lock(&tty->winsize_mutex);
2239 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
2242 /* Signal the foreground process group */
2243 pgrp = tty_get_pgrp(tty);
2245 kill_pgrp(pgrp, SIGWINCH, 1);
2250 mutex_unlock(&tty->winsize_mutex);
2253 EXPORT_SYMBOL(tty_do_resize);
2256 * tiocswinsz - implement window size set ioctl
2257 * @tty; tty side of tty
2258 * @arg: user buffer for result
2260 * Copies the user idea of the window size to the kernel. Traditionally
2261 * this is just advisory information but for the Linux console it
2262 * actually has driver level meaning and triggers a VC resize.
2265 * Driver dependent. The default do_resize method takes the
2266 * tty termios mutex and ctrl_lock. The console takes its own lock
2267 * then calls into the default method.
2270 static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
2272 struct winsize tmp_ws;
2273 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2276 if (tty->ops->resize)
2277 return tty->ops->resize(tty, &tmp_ws);
2279 return tty_do_resize(tty, &tmp_ws);
2283 * tioccons - allow admin to move logical console
2284 * @file: the file to become console
2286 * Allow the administrator to move the redirected console device
2288 * Locking: uses redirect_lock to guard the redirect information
2291 static int tioccons(struct file *file)
2293 if (!capable(CAP_SYS_ADMIN))
2295 if (file->f_op->write == redirected_tty_write) {
2297 spin_lock(&redirect_lock);
2300 spin_unlock(&redirect_lock);
2305 spin_lock(&redirect_lock);
2307 spin_unlock(&redirect_lock);
2310 redirect = get_file(file);
2311 spin_unlock(&redirect_lock);
2316 * fionbio - non blocking ioctl
2317 * @file: file to set blocking value
2318 * @p: user parameter
2320 * Historical tty interfaces had a blocking control ioctl before
2321 * the generic functionality existed. This piece of history is preserved
2322 * in the expected tty API of posix OS's.
2324 * Locking: none, the open file handle ensures it won't go away.
2327 static int fionbio(struct file *file, int __user *p)
2331 if (get_user(nonblock, p))
2334 spin_lock(&file->f_lock);
2336 file->f_flags |= O_NONBLOCK;
2338 file->f_flags &= ~O_NONBLOCK;
2339 spin_unlock(&file->f_lock);
2344 * tiocsetd - set line discipline
2346 * @p: pointer to user data
2348 * Set the line discipline according to user request.
2350 * Locking: see tty_set_ldisc, this function is just a helper
2353 static int tiocsetd(struct tty_struct *tty, int __user *p)
2358 if (get_user(disc, p))
2361 ret = tty_set_ldisc(tty, disc);
2367 * tiocgetd - get line discipline
2369 * @p: pointer to user data
2371 * Retrieves the line discipline id directly from the ldisc.
2373 * Locking: waits for ldisc reference (in case the line discipline
2374 * is changing or the tty is being hungup)
2377 static int tiocgetd(struct tty_struct *tty, int __user *p)
2379 struct tty_ldisc *ld;
2382 ld = tty_ldisc_ref_wait(tty);
2385 ret = put_user(ld->ops->num, p);
2386 tty_ldisc_deref(ld);
2391 * send_break - performed time break
2392 * @tty: device to break on
2393 * @duration: timeout in mS
2395 * Perform a timed break on hardware that lacks its own driver level
2396 * timed break functionality.
2399 * atomic_write_lock serializes
2403 static int send_break(struct tty_struct *tty, unsigned int duration)
2407 if (tty->ops->break_ctl == NULL)
2410 if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2411 retval = tty->ops->break_ctl(tty, duration);
2413 /* Do the work ourselves */
2414 if (tty_write_lock(tty, 0) < 0)
2416 retval = tty->ops->break_ctl(tty, -1);
2419 if (!signal_pending(current))
2420 msleep_interruptible(duration);
2421 retval = tty->ops->break_ctl(tty, 0);
2423 tty_write_unlock(tty);
2424 if (signal_pending(current))
2431 * tty_tiocmget - get modem status
2433 * @file: user file pointer
2434 * @p: pointer to result
2436 * Obtain the modem status bits from the tty driver if the feature
2437 * is supported. Return -ENOTTY if it is not available.
2439 * Locking: none (up to the driver)
2442 static int tty_tiocmget(struct tty_struct *tty, int __user *p)
2444 int retval = -ENOTTY;
2446 if (tty->ops->tiocmget) {
2447 retval = tty->ops->tiocmget(tty);
2450 retval = put_user(retval, p);
2456 * tty_tiocmset - set modem status
2458 * @cmd: command - clear bits, set bits or set all
2459 * @p: pointer to desired bits
2461 * Set the modem status bits from the tty driver if the feature
2462 * is supported. Return -ENOTTY if it is not available.
2464 * Locking: none (up to the driver)
2467 static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
2471 unsigned int set, clear, val;
2473 if (tty->ops->tiocmset == NULL)
2476 retval = get_user(val, p);
2492 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2493 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2494 return tty->ops->tiocmset(tty, set, clear);
2497 static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
2499 int retval = -EINVAL;
2500 struct serial_icounter_struct icount;
2501 memset(&icount, 0, sizeof(icount));
2502 if (tty->ops->get_icount)
2503 retval = tty->ops->get_icount(tty, &icount);
2506 if (copy_to_user(arg, &icount, sizeof(icount)))
2511 static void tty_warn_deprecated_flags(struct serial_struct __user *ss)
2513 static DEFINE_RATELIMIT_STATE(depr_flags,
2514 DEFAULT_RATELIMIT_INTERVAL,
2515 DEFAULT_RATELIMIT_BURST);
2516 char comm[TASK_COMM_LEN];
2519 if (get_user(flags, &ss->flags))
2522 flags &= ASYNC_DEPRECATED;
2524 if (flags && __ratelimit(&depr_flags))
2525 pr_warn("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
2526 __func__, get_task_comm(comm, current), flags);
2530 * if pty, return the slave side (real_tty)
2531 * otherwise, return self
2533 static struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
2535 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2536 tty->driver->subtype == PTY_TYPE_MASTER)
2542 * Split this up, as gcc can choke on it otherwise..
2544 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2546 struct tty_struct *tty = file_tty(file);
2547 struct tty_struct *real_tty;
2548 void __user *p = (void __user *)arg;
2550 struct tty_ldisc *ld;
2552 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2555 real_tty = tty_pair_get_tty(tty);
2558 * Factor out some common prep work
2566 retval = tty_check_change(tty);
2569 if (cmd != TIOCCBRK) {
2570 tty_wait_until_sent(tty, 0);
2571 if (signal_pending(current))
2582 return tiocsti(tty, p);
2584 return tiocgwinsz(real_tty, p);
2586 return tiocswinsz(real_tty, p);
2588 return real_tty != tty ? -EINVAL : tioccons(file);
2590 return fionbio(file, p);
2592 set_bit(TTY_EXCLUSIVE, &tty->flags);
2595 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2599 int excl = test_bit(TTY_EXCLUSIVE, &tty->flags);
2600 return put_user(excl, (int __user *)p);
2603 return tiocgetd(tty, p);
2605 return tiocsetd(tty, p);
2607 if (!capable(CAP_SYS_ADMIN))
2613 unsigned int ret = new_encode_dev(tty_devnum(real_tty));
2614 return put_user(ret, (unsigned int __user *)p);
2619 case TIOCSBRK: /* Turn break on, unconditionally */
2620 if (tty->ops->break_ctl)
2621 return tty->ops->break_ctl(tty, -1);
2623 case TIOCCBRK: /* Turn break off, unconditionally */
2624 if (tty->ops->break_ctl)
2625 return tty->ops->break_ctl(tty, 0);
2627 case TCSBRK: /* SVID version: non-zero arg --> no break */
2628 /* non-zero arg means wait for all output data
2629 * to be sent (performed above) but don't send break.
2630 * This is used by the tcdrain() termios function.
2633 return send_break(tty, 250);
2635 case TCSBRKP: /* support for POSIX tcsendbreak() */
2636 return send_break(tty, arg ? arg*100 : 250);
2639 return tty_tiocmget(tty, p);
2643 return tty_tiocmset(tty, cmd, p);
2645 retval = tty_tiocgicount(tty, p);
2646 /* For the moment allow fall through to the old method */
2647 if (retval != -EINVAL)
2654 /* flush tty buffer and allow ldisc to process ioctl */
2655 tty_buffer_flush(tty, NULL);
2660 tty_warn_deprecated_flags(p);
2663 /* Special because the struct file is needed */
2664 return ptm_open_peer(file, tty, (int)arg);
2666 retval = tty_jobctrl_ioctl(tty, real_tty, file, cmd, arg);
2667 if (retval != -ENOIOCTLCMD)
2670 if (tty->ops->ioctl) {
2671 retval = tty->ops->ioctl(tty, cmd, arg);
2672 if (retval != -ENOIOCTLCMD)
2675 ld = tty_ldisc_ref_wait(tty);
2677 return hung_up_tty_ioctl(file, cmd, arg);
2679 if (ld->ops->ioctl) {
2680 retval = ld->ops->ioctl(tty, file, cmd, arg);
2681 if (retval == -ENOIOCTLCMD)
2684 tty_ldisc_deref(ld);
2688 #ifdef CONFIG_COMPAT
2689 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2692 struct tty_struct *tty = file_tty(file);
2693 struct tty_ldisc *ld;
2694 int retval = -ENOIOCTLCMD;
2696 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2699 if (tty->ops->compat_ioctl) {
2700 retval = tty->ops->compat_ioctl(tty, cmd, arg);
2701 if (retval != -ENOIOCTLCMD)
2705 ld = tty_ldisc_ref_wait(tty);
2707 return hung_up_tty_compat_ioctl(file, cmd, arg);
2708 if (ld->ops->compat_ioctl)
2709 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
2711 retval = n_tty_compat_ioctl_helper(tty, file, cmd, arg);
2712 tty_ldisc_deref(ld);
2718 static int this_tty(const void *t, struct file *file, unsigned fd)
2720 if (likely(file->f_op->read != tty_read))
2722 return file_tty(file) != t ? 0 : fd + 1;
2726 * This implements the "Secure Attention Key" --- the idea is to
2727 * prevent trojan horses by killing all processes associated with this
2728 * tty when the user hits the "Secure Attention Key". Required for
2729 * super-paranoid applications --- see the Orange Book for more details.
2731 * This code could be nicer; ideally it should send a HUP, wait a few
2732 * seconds, then send a INT, and then a KILL signal. But you then
2733 * have to coordinate with the init process, since all processes associated
2734 * with the current tty must be dead before the new getty is allowed
2737 * Now, if it would be correct ;-/ The current code has a nasty hole -
2738 * it doesn't catch files in flight. We may send the descriptor to ourselves
2739 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
2741 * Nasty bug: do_SAK is being called in interrupt context. This can
2742 * deadlock. We punt it up to process context. AKPM - 16Mar2001
2744 void __do_SAK(struct tty_struct *tty)
2749 struct task_struct *g, *p;
2750 struct pid *session;
2752 unsigned long flags;
2757 spin_lock_irqsave(&tty->ctrl_lock, flags);
2758 session = get_pid(tty->session);
2759 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2761 tty_ldisc_flush(tty);
2763 tty_driver_flush_buffer(tty);
2765 read_lock(&tasklist_lock);
2766 /* Kill the entire session */
2767 do_each_pid_task(session, PIDTYPE_SID, p) {
2768 tty_notice(tty, "SAK: killed process %d (%s): by session\n",
2769 task_pid_nr(p), p->comm);
2770 send_sig(SIGKILL, p, 1);
2771 } while_each_pid_task(session, PIDTYPE_SID, p);
2773 /* Now kill any processes that happen to have the tty open */
2774 do_each_thread(g, p) {
2775 if (p->signal->tty == tty) {
2776 tty_notice(tty, "SAK: killed process %d (%s): by controlling tty\n",
2777 task_pid_nr(p), p->comm);
2778 send_sig(SIGKILL, p, 1);
2782 i = iterate_fd(p->files, 0, this_tty, tty);
2784 tty_notice(tty, "SAK: killed process %d (%s): by fd#%d\n",
2785 task_pid_nr(p), p->comm, i - 1);
2786 force_sig(SIGKILL, p);
2789 } while_each_thread(g, p);
2790 read_unlock(&tasklist_lock);
2795 static void do_SAK_work(struct work_struct *work)
2797 struct tty_struct *tty =
2798 container_of(work, struct tty_struct, SAK_work);
2803 * The tq handling here is a little racy - tty->SAK_work may already be queued.
2804 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
2805 * the values which we write to it will be identical to the values which it
2806 * already has. --akpm
2808 void do_SAK(struct tty_struct *tty)
2812 schedule_work(&tty->SAK_work);
2815 EXPORT_SYMBOL(do_SAK);
2817 static int dev_match_devt(struct device *dev, const void *data)
2819 const dev_t *devt = data;
2820 return dev->devt == *devt;
2823 /* Must put_device() after it's unused! */
2824 static struct device *tty_get_device(struct tty_struct *tty)
2826 dev_t devt = tty_devnum(tty);
2827 return class_find_device(tty_class, NULL, &devt, dev_match_devt);
2834 * This subroutine allocates and initializes a tty structure.
2836 * Locking: none - tty in question is not exposed at this point
2839 struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
2841 struct tty_struct *tty;
2843 tty = kzalloc(sizeof(*tty), GFP_KERNEL);
2847 kref_init(&tty->kref);
2848 tty->magic = TTY_MAGIC;
2849 if (tty_ldisc_init(tty)) {
2853 tty->session = NULL;
2855 mutex_init(&tty->legacy_mutex);
2856 mutex_init(&tty->throttle_mutex);
2857 init_rwsem(&tty->termios_rwsem);
2858 mutex_init(&tty->winsize_mutex);
2859 init_ldsem(&tty->ldisc_sem);
2860 init_waitqueue_head(&tty->write_wait);
2861 init_waitqueue_head(&tty->read_wait);
2862 INIT_WORK(&tty->hangup_work, do_tty_hangup);
2863 mutex_init(&tty->atomic_write_lock);
2864 spin_lock_init(&tty->ctrl_lock);
2865 spin_lock_init(&tty->flow_lock);
2866 spin_lock_init(&tty->files_lock);
2867 INIT_LIST_HEAD(&tty->tty_files);
2868 INIT_WORK(&tty->SAK_work, do_SAK_work);
2870 tty->driver = driver;
2871 tty->ops = driver->ops;
2873 tty_line_name(driver, idx, tty->name);
2874 tty->dev = tty_get_device(tty);
2880 * tty_put_char - write one character to a tty
2884 * Write one byte to the tty using the provided put_char method
2885 * if present. Returns the number of characters successfully output.
2887 * Note: the specific put_char operation in the driver layer may go
2888 * away soon. Don't call it directly, use this method
2891 int tty_put_char(struct tty_struct *tty, unsigned char ch)
2893 if (tty->ops->put_char)
2894 return tty->ops->put_char(tty, ch);
2895 return tty->ops->write(tty, &ch, 1);
2897 EXPORT_SYMBOL_GPL(tty_put_char);
2899 struct class *tty_class;
2901 static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
2902 unsigned int index, unsigned int count)
2906 /* init here, since reused cdevs cause crashes */
2907 driver->cdevs[index] = cdev_alloc();
2908 if (!driver->cdevs[index])
2910 driver->cdevs[index]->ops = &tty_fops;
2911 driver->cdevs[index]->owner = driver->owner;
2912 err = cdev_add(driver->cdevs[index], dev, count);
2914 kobject_put(&driver->cdevs[index]->kobj);
2919 * tty_register_device - register a tty device
2920 * @driver: the tty driver that describes the tty device
2921 * @index: the index in the tty driver for this tty device
2922 * @device: a struct device that is associated with this tty device.
2923 * This field is optional, if there is no known struct device
2924 * for this tty device it can be set to NULL safely.
2926 * Returns a pointer to the struct device for this tty device
2927 * (or ERR_PTR(-EFOO) on error).
2929 * This call is required to be made to register an individual tty device
2930 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
2931 * that bit is not set, this function should not be called by a tty
2937 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
2938 struct device *device)
2940 return tty_register_device_attr(driver, index, device, NULL, NULL);
2942 EXPORT_SYMBOL(tty_register_device);
2944 static void tty_device_create_release(struct device *dev)
2946 dev_dbg(dev, "releasing...\n");
2951 * tty_register_device_attr - register a tty device
2952 * @driver: the tty driver that describes the tty device
2953 * @index: the index in the tty driver for this tty device
2954 * @device: a struct device that is associated with this tty device.
2955 * This field is optional, if there is no known struct device
2956 * for this tty device it can be set to NULL safely.
2957 * @drvdata: Driver data to be set to device.
2958 * @attr_grp: Attribute group to be set on device.
2960 * Returns a pointer to the struct device for this tty device
2961 * (or ERR_PTR(-EFOO) on error).
2963 * This call is required to be made to register an individual tty device
2964 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
2965 * that bit is not set, this function should not be called by a tty
2970 struct device *tty_register_device_attr(struct tty_driver *driver,
2971 unsigned index, struct device *device,
2973 const struct attribute_group **attr_grp)
2976 dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
2977 struct ktermios *tp;
2981 if (index >= driver->num) {
2982 pr_err("%s: Attempt to register invalid tty line number (%d)\n",
2983 driver->name, index);
2984 return ERR_PTR(-EINVAL);
2987 if (driver->type == TTY_DRIVER_TYPE_PTY)
2988 pty_line_name(driver, index, name);
2990 tty_line_name(driver, index, name);
2992 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
2994 return ERR_PTR(-ENOMEM);
2997 dev->class = tty_class;
2998 dev->parent = device;
2999 dev->release = tty_device_create_release;
3000 dev_set_name(dev, "%s", name);
3001 dev->groups = attr_grp;
3002 dev_set_drvdata(dev, drvdata);
3004 dev_set_uevent_suppress(dev, 1);
3006 retval = device_register(dev);
3010 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3012 * Free any saved termios data so that the termios state is
3013 * reset when reusing a minor number.
3015 tp = driver->termios[index];
3017 driver->termios[index] = NULL;
3021 retval = tty_cdev_add(driver, devt, index, 1);
3026 dev_set_uevent_suppress(dev, 0);
3027 kobject_uevent(&dev->kobj, KOBJ_ADD);
3036 return ERR_PTR(retval);
3038 EXPORT_SYMBOL_GPL(tty_register_device_attr);
3041 * tty_unregister_device - unregister a tty device
3042 * @driver: the tty driver that describes the tty device
3043 * @index: the index in the tty driver for this tty device
3045 * If a tty device is registered with a call to tty_register_device() then
3046 * this function must be called when the tty device is gone.
3051 void tty_unregister_device(struct tty_driver *driver, unsigned index)
3053 device_destroy(tty_class,
3054 MKDEV(driver->major, driver->minor_start) + index);
3055 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3056 cdev_del(driver->cdevs[index]);
3057 driver->cdevs[index] = NULL;
3060 EXPORT_SYMBOL(tty_unregister_device);
3063 * __tty_alloc_driver -- allocate tty driver
3064 * @lines: count of lines this driver can handle at most
3065 * @owner: module which is responsible for this driver
3066 * @flags: some of TTY_DRIVER_* flags, will be set in driver->flags
3068 * This should not be called directly, some of the provided macros should be
3069 * used instead. Use IS_ERR and friends on @retval.
3071 struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
3072 unsigned long flags)
3074 struct tty_driver *driver;
3075 unsigned int cdevs = 1;
3078 if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
3079 return ERR_PTR(-EINVAL);
3081 driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
3083 return ERR_PTR(-ENOMEM);
3085 kref_init(&driver->kref);
3086 driver->magic = TTY_DRIVER_MAGIC;
3087 driver->num = lines;
3088 driver->owner = owner;
3089 driver->flags = flags;
3091 if (!(flags & TTY_DRIVER_DEVPTS_MEM)) {
3092 driver->ttys = kcalloc(lines, sizeof(*driver->ttys),
3094 driver->termios = kcalloc(lines, sizeof(*driver->termios),
3096 if (!driver->ttys || !driver->termios) {
3102 if (!(flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3103 driver->ports = kcalloc(lines, sizeof(*driver->ports),
3105 if (!driver->ports) {
3112 driver->cdevs = kcalloc(cdevs, sizeof(*driver->cdevs), GFP_KERNEL);
3113 if (!driver->cdevs) {
3120 kfree(driver->ports);
3121 kfree(driver->ttys);
3122 kfree(driver->termios);
3123 kfree(driver->cdevs);
3125 return ERR_PTR(err);
3127 EXPORT_SYMBOL(__tty_alloc_driver);
3129 static void destruct_tty_driver(struct kref *kref)
3131 struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
3133 struct ktermios *tp;
3135 if (driver->flags & TTY_DRIVER_INSTALLED) {
3136 for (i = 0; i < driver->num; i++) {
3137 tp = driver->termios[i];
3139 driver->termios[i] = NULL;
3142 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3143 tty_unregister_device(driver, i);
3145 proc_tty_unregister_driver(driver);
3146 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
3147 cdev_del(driver->cdevs[0]);
3149 kfree(driver->cdevs);
3150 kfree(driver->ports);
3151 kfree(driver->termios);
3152 kfree(driver->ttys);
3156 void tty_driver_kref_put(struct tty_driver *driver)
3158 kref_put(&driver->kref, destruct_tty_driver);
3160 EXPORT_SYMBOL(tty_driver_kref_put);
3162 void tty_set_operations(struct tty_driver *driver,
3163 const struct tty_operations *op)
3167 EXPORT_SYMBOL(tty_set_operations);
3169 void put_tty_driver(struct tty_driver *d)
3171 tty_driver_kref_put(d);
3173 EXPORT_SYMBOL(put_tty_driver);
3176 * Called by a tty driver to register itself.
3178 int tty_register_driver(struct tty_driver *driver)
3185 if (!driver->major) {
3186 error = alloc_chrdev_region(&dev, driver->minor_start,
3187 driver->num, driver->name);
3189 driver->major = MAJOR(dev);
3190 driver->minor_start = MINOR(dev);
3193 dev = MKDEV(driver->major, driver->minor_start);
3194 error = register_chrdev_region(dev, driver->num, driver->name);
3199 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) {
3200 error = tty_cdev_add(driver, dev, 0, driver->num);
3202 goto err_unreg_char;
3205 mutex_lock(&tty_mutex);
3206 list_add(&driver->tty_drivers, &tty_drivers);
3207 mutex_unlock(&tty_mutex);
3209 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
3210 for (i = 0; i < driver->num; i++) {
3211 d = tty_register_device(driver, i, NULL);
3214 goto err_unreg_devs;
3218 proc_tty_register_driver(driver);
3219 driver->flags |= TTY_DRIVER_INSTALLED;
3223 for (i--; i >= 0; i--)
3224 tty_unregister_device(driver, i);
3226 mutex_lock(&tty_mutex);
3227 list_del(&driver->tty_drivers);
3228 mutex_unlock(&tty_mutex);
3231 unregister_chrdev_region(dev, driver->num);
3235 EXPORT_SYMBOL(tty_register_driver);
3238 * Called by a tty driver to unregister itself.
3240 int tty_unregister_driver(struct tty_driver *driver)
3244 if (driver->refcount)
3247 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3249 mutex_lock(&tty_mutex);
3250 list_del(&driver->tty_drivers);
3251 mutex_unlock(&tty_mutex);
3255 EXPORT_SYMBOL(tty_unregister_driver);
3257 dev_t tty_devnum(struct tty_struct *tty)
3259 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3261 EXPORT_SYMBOL(tty_devnum);
3263 void tty_default_fops(struct file_operations *fops)
3268 static char *tty_devnode(struct device *dev, umode_t *mode)
3272 if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
3273 dev->devt == MKDEV(TTYAUX_MAJOR, 2))
3278 static int __init tty_class_init(void)
3280 tty_class = class_create(THIS_MODULE, "tty");
3281 if (IS_ERR(tty_class))
3282 return PTR_ERR(tty_class);
3283 tty_class->devnode = tty_devnode;
3287 postcore_initcall(tty_class_init);
3289 /* 3/2004 jmc: why do these devices exist? */
3290 static struct cdev tty_cdev, console_cdev;
3292 static ssize_t show_cons_active(struct device *dev,
3293 struct device_attribute *attr, char *buf)
3295 struct console *cs[16];
3301 for_each_console(c) {
3306 if ((c->flags & CON_ENABLED) == 0)
3309 if (i >= ARRAY_SIZE(cs))
3313 int index = cs[i]->index;
3314 struct tty_driver *drv = cs[i]->device(cs[i], &index);
3316 /* don't resolve tty0 as some programs depend on it */
3317 if (drv && (cs[i]->index > 0 || drv->major != TTY_MAJOR))
3318 count += tty_line_name(drv, index, buf + count);
3320 count += sprintf(buf + count, "%s%d",
3321 cs[i]->name, cs[i]->index);
3323 count += sprintf(buf + count, "%c", i ? ' ':'\n');
3329 static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
3331 static struct attribute *cons_dev_attrs[] = {
3332 &dev_attr_active.attr,
3336 ATTRIBUTE_GROUPS(cons_dev);
3338 static struct device *consdev;
3340 void console_sysfs_notify(void)
3343 sysfs_notify(&consdev->kobj, NULL, "active");
3347 * Ok, now we can initialize the rest of the tty devices and can count
3348 * on memory allocations, interrupts etc..
3350 int __init tty_init(void)
3353 cdev_init(&tty_cdev, &tty_fops);
3354 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3355 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3356 panic("Couldn't register /dev/tty driver\n");
3357 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
3359 cdev_init(&console_cdev, &console_fops);
3360 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3361 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3362 panic("Couldn't register /dev/console driver\n");
3363 consdev = device_create_with_groups(tty_class, NULL,
3364 MKDEV(TTYAUX_MAJOR, 1), NULL,
3365 cons_dev_groups, "console");
3366 if (IS_ERR(consdev))
3370 vty_init(&console_fops);