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 unsigned int 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 (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 unsigned int hung_up_tty_poll(struct file *filp, poll_table *wait)
448 return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM;
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;
516 * tty_wakeup - request more data
519 * Internal and external helper for wakeups of tty. This function
520 * informs the line discipline if present that the driver is ready
521 * to receive more output data.
524 void tty_wakeup(struct tty_struct *tty)
526 struct tty_ldisc *ld;
528 if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
529 ld = tty_ldisc_ref(tty);
531 if (ld->ops->write_wakeup)
532 ld->ops->write_wakeup(tty);
536 wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
539 EXPORT_SYMBOL_GPL(tty_wakeup);
542 * __tty_hangup - actual handler for hangup events
545 * This can be called by a "kworker" kernel thread. That is process
546 * synchronous but doesn't hold any locks, so we need to make sure we
547 * have the appropriate locks for what we're doing.
549 * The hangup event clears any pending redirections onto the hung up
550 * device. It ensures future writes will error and it does the needed
551 * line discipline hangup and signal delivery. The tty object itself
556 * redirect lock for undoing redirection
557 * file list lock for manipulating list of ttys
558 * tty_ldiscs_lock from called functions
559 * termios_rwsem resetting termios data
560 * tasklist_lock to walk task list for hangup event
561 * ->siglock to protect ->signal/->sighand
563 static void __tty_hangup(struct tty_struct *tty, int exit_session)
565 struct file *cons_filp = NULL;
566 struct file *filp, *f = NULL;
567 struct tty_file_private *priv;
568 int closecount = 0, n;
575 spin_lock(&redirect_lock);
576 if (redirect && file_tty(redirect) == tty) {
580 spin_unlock(&redirect_lock);
584 if (test_bit(TTY_HUPPED, &tty->flags)) {
589 /* inuse_filps is protected by the single tty lock,
590 this really needs to change if we want to flush the
591 workqueue with the lock held */
592 check_tty_count(tty, "tty_hangup");
594 spin_lock(&tty->files_lock);
595 /* This breaks for file handles being sent over AF_UNIX sockets ? */
596 list_for_each_entry(priv, &tty->tty_files, list) {
598 if (filp->f_op->write == redirected_tty_write)
600 if (filp->f_op->write != tty_write)
603 __tty_fasync(-1, filp, 0); /* can't block */
604 filp->f_op = &hung_up_tty_fops;
606 spin_unlock(&tty->files_lock);
608 refs = tty_signal_session_leader(tty, exit_session);
609 /* Account for the p->signal references we killed */
613 tty_ldisc_hangup(tty, cons_filp != NULL);
615 spin_lock_irq(&tty->ctrl_lock);
616 clear_bit(TTY_THROTTLED, &tty->flags);
617 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
618 put_pid(tty->session);
622 tty->ctrl_status = 0;
623 spin_unlock_irq(&tty->ctrl_lock);
626 * If one of the devices matches a console pointer, we
627 * cannot just call hangup() because that will cause
628 * tty->count and state->count to go out of sync.
629 * So we just call close() the right number of times.
633 for (n = 0; n < closecount; n++)
634 tty->ops->close(tty, cons_filp);
635 } else if (tty->ops->hangup)
636 tty->ops->hangup(tty);
638 * We don't want to have driver/ldisc interactions beyond the ones
639 * we did here. The driver layer expects no calls after ->hangup()
640 * from the ldisc side, which is now guaranteed.
642 set_bit(TTY_HUPPED, &tty->flags);
649 static void do_tty_hangup(struct work_struct *work)
651 struct tty_struct *tty =
652 container_of(work, struct tty_struct, hangup_work);
654 __tty_hangup(tty, 0);
658 * tty_hangup - trigger a hangup event
659 * @tty: tty to hangup
661 * A carrier loss (virtual or otherwise) has occurred on this like
662 * schedule a hangup sequence to run after this event.
665 void tty_hangup(struct tty_struct *tty)
667 tty_debug_hangup(tty, "hangup\n");
668 schedule_work(&tty->hangup_work);
671 EXPORT_SYMBOL(tty_hangup);
674 * tty_vhangup - process vhangup
675 * @tty: tty to hangup
677 * The user has asked via system call for the terminal to be hung up.
678 * We do this synchronously so that when the syscall returns the process
679 * is complete. That guarantee is necessary for security reasons.
682 void tty_vhangup(struct tty_struct *tty)
684 tty_debug_hangup(tty, "vhangup\n");
685 __tty_hangup(tty, 0);
688 EXPORT_SYMBOL(tty_vhangup);
692 * tty_vhangup_self - process vhangup for own ctty
694 * Perform a vhangup on the current controlling tty
697 void tty_vhangup_self(void)
699 struct tty_struct *tty;
701 tty = get_current_tty();
709 * tty_vhangup_session - hangup session leader exit
710 * @tty: tty to hangup
712 * The session leader is exiting and hanging up its controlling terminal.
713 * Every process in the foreground process group is signalled SIGHUP.
715 * We do this synchronously so that when the syscall returns the process
716 * is complete. That guarantee is necessary for security reasons.
719 void tty_vhangup_session(struct tty_struct *tty)
721 tty_debug_hangup(tty, "session hangup\n");
722 __tty_hangup(tty, 1);
726 * tty_hung_up_p - was tty hung up
727 * @filp: file pointer of tty
729 * Return true if the tty has been subject to a vhangup or a carrier
733 int tty_hung_up_p(struct file *filp)
735 return (filp && filp->f_op == &hung_up_tty_fops);
738 EXPORT_SYMBOL(tty_hung_up_p);
741 * stop_tty - propagate flow control
744 * Perform flow control to the driver. May be called
745 * on an already stopped device and will not re-call the driver
748 * This functionality is used by both the line disciplines for
749 * halting incoming flow and by the driver. It may therefore be
750 * called from any context, may be under the tty atomic_write_lock
757 void __stop_tty(struct tty_struct *tty)
766 void stop_tty(struct tty_struct *tty)
770 spin_lock_irqsave(&tty->flow_lock, flags);
772 spin_unlock_irqrestore(&tty->flow_lock, flags);
774 EXPORT_SYMBOL(stop_tty);
777 * start_tty - propagate flow control
780 * Start a tty that has been stopped if at all possible. If this
781 * tty was previous stopped and is now being started, the driver
782 * start method is invoked and the line discipline woken.
788 void __start_tty(struct tty_struct *tty)
790 if (!tty->stopped || tty->flow_stopped)
794 tty->ops->start(tty);
798 void start_tty(struct tty_struct *tty)
802 spin_lock_irqsave(&tty->flow_lock, flags);
804 spin_unlock_irqrestore(&tty->flow_lock, flags);
806 EXPORT_SYMBOL(start_tty);
808 static void tty_update_time(struct timespec *time)
810 unsigned long sec = get_seconds();
813 * We only care if the two values differ in anything other than the
814 * lower three bits (i.e every 8 seconds). If so, then we can update
815 * the time of the tty device, otherwise it could be construded as a
816 * security leak to let userspace know the exact timing of the tty.
818 if ((sec ^ time->tv_sec) & ~7)
823 * tty_read - read method for tty device files
824 * @file: pointer to tty file
826 * @count: size of user buffer
829 * Perform the read system call function on this terminal device. Checks
830 * for hung up devices before calling the line discipline method.
833 * Locks the line discipline internally while needed. Multiple
834 * read calls may be outstanding in parallel.
837 static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
841 struct inode *inode = file_inode(file);
842 struct tty_struct *tty = file_tty(file);
843 struct tty_ldisc *ld;
845 if (tty_paranoia_check(tty, inode, "tty_read"))
847 if (!tty || tty_io_error(tty))
850 /* We want to wait for the line discipline to sort out in this
852 ld = tty_ldisc_ref_wait(tty);
854 return hung_up_tty_read(file, buf, count, ppos);
856 i = ld->ops->read(tty, file, buf, count);
862 tty_update_time(&inode->i_atime);
867 static void tty_write_unlock(struct tty_struct *tty)
869 mutex_unlock(&tty->atomic_write_lock);
870 wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
873 static int tty_write_lock(struct tty_struct *tty, int ndelay)
875 if (!mutex_trylock(&tty->atomic_write_lock)) {
878 if (mutex_lock_interruptible(&tty->atomic_write_lock))
885 * Split writes up in sane blocksizes to avoid
886 * denial-of-service type attacks
888 static inline ssize_t do_tty_write(
889 ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
890 struct tty_struct *tty,
892 const char __user *buf,
895 ssize_t ret, written = 0;
898 ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
903 * We chunk up writes into a temporary buffer. This
904 * simplifies low-level drivers immensely, since they
905 * don't have locking issues and user mode accesses.
907 * But if TTY_NO_WRITE_SPLIT is set, we should use a
910 * The default chunk-size is 2kB, because the NTTY
911 * layer has problems with bigger chunks. It will
912 * claim to be able to handle more characters than
915 * FIXME: This can probably go away now except that 64K chunks
916 * are too likely to fail unless switched to vmalloc...
919 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
924 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
925 if (tty->write_cnt < chunk) {
926 unsigned char *buf_chunk;
931 buf_chunk = kmalloc(chunk, GFP_KERNEL);
936 kfree(tty->write_buf);
937 tty->write_cnt = chunk;
938 tty->write_buf = buf_chunk;
941 /* Do the write .. */
947 if (copy_from_user(tty->write_buf, buf, size))
949 ret = write(tty, file, tty->write_buf, size);
958 if (signal_pending(current))
963 tty_update_time(&file_inode(file)->i_mtime);
967 tty_write_unlock(tty);
972 * tty_write_message - write a message to a certain tty, not just the console.
973 * @tty: the destination tty_struct
974 * @msg: the message to write
976 * This is used for messages that need to be redirected to a specific tty.
977 * We don't put it into the syslog queue right now maybe in the future if
980 * We must still hold the BTM and test the CLOSING flag for the moment.
983 void tty_write_message(struct tty_struct *tty, char *msg)
986 mutex_lock(&tty->atomic_write_lock);
988 if (tty->ops->write && tty->count > 0)
989 tty->ops->write(tty, msg, strlen(msg));
991 tty_write_unlock(tty);
998 * tty_write - write method for tty device file
999 * @file: tty file pointer
1000 * @buf: user data to write
1001 * @count: bytes to write
1004 * Write data to a tty device via the line discipline.
1007 * Locks the line discipline as required
1008 * Writes to the tty driver are serialized by the atomic_write_lock
1009 * and are then processed in chunks to the device. The line discipline
1010 * write method will not be invoked in parallel for each device.
1013 static ssize_t tty_write(struct file *file, const char __user *buf,
1014 size_t count, loff_t *ppos)
1016 struct tty_struct *tty = file_tty(file);
1017 struct tty_ldisc *ld;
1020 if (tty_paranoia_check(tty, file_inode(file), "tty_write"))
1022 if (!tty || !tty->ops->write || tty_io_error(tty))
1024 /* Short term debug to catch buggy drivers */
1025 if (tty->ops->write_room == NULL)
1026 tty_err(tty, "missing write_room method\n");
1027 ld = tty_ldisc_ref_wait(tty);
1029 return hung_up_tty_write(file, buf, count, ppos);
1030 if (!ld->ops->write)
1033 ret = do_tty_write(ld->ops->write, tty, file, buf, count);
1034 tty_ldisc_deref(ld);
1038 ssize_t redirected_tty_write(struct file *file, const char __user *buf,
1039 size_t count, loff_t *ppos)
1041 struct file *p = NULL;
1043 spin_lock(&redirect_lock);
1045 p = get_file(redirect);
1046 spin_unlock(&redirect_lock);
1050 res = vfs_write(p, buf, count, &p->f_pos);
1054 return tty_write(file, buf, count, ppos);
1058 * tty_send_xchar - send priority character
1060 * Send a high priority character to the tty even if stopped
1062 * Locking: none for xchar method, write ordering for write method.
1065 int tty_send_xchar(struct tty_struct *tty, char ch)
1067 int was_stopped = tty->stopped;
1069 if (tty->ops->send_xchar) {
1070 down_read(&tty->termios_rwsem);
1071 tty->ops->send_xchar(tty, ch);
1072 up_read(&tty->termios_rwsem);
1076 if (tty_write_lock(tty, 0) < 0)
1077 return -ERESTARTSYS;
1079 down_read(&tty->termios_rwsem);
1082 tty->ops->write(tty, &ch, 1);
1085 up_read(&tty->termios_rwsem);
1086 tty_write_unlock(tty);
1090 static char ptychar[] = "pqrstuvwxyzabcde";
1093 * pty_line_name - generate name for a pty
1094 * @driver: the tty driver in use
1095 * @index: the minor number
1096 * @p: output buffer of at least 6 bytes
1098 * Generate a name from a driver reference and write it to the output
1103 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1105 int i = index + driver->name_base;
1106 /* ->name is initialized to "ttyp", but "tty" is expected */
1107 sprintf(p, "%s%c%x",
1108 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1109 ptychar[i >> 4 & 0xf], i & 0xf);
1113 * tty_line_name - generate name for a tty
1114 * @driver: the tty driver in use
1115 * @index: the minor number
1116 * @p: output buffer of at least 7 bytes
1118 * Generate a name from a driver reference and write it to the output
1123 static ssize_t tty_line_name(struct tty_driver *driver, int index, char *p)
1125 if (driver->flags & TTY_DRIVER_UNNUMBERED_NODE)
1126 return sprintf(p, "%s", driver->name);
1128 return sprintf(p, "%s%d", driver->name,
1129 index + driver->name_base);
1133 * tty_driver_lookup_tty() - find an existing tty, if any
1134 * @driver: the driver for the tty
1135 * @idx: the minor number
1137 * Return the tty, if found. If not found, return NULL or ERR_PTR() if the
1138 * driver lookup() method returns an error.
1140 * Locking: tty_mutex must be held. If the tty is found, bump the tty kref.
1142 static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
1143 struct file *file, int idx)
1145 struct tty_struct *tty;
1147 if (driver->ops->lookup)
1149 tty = ERR_PTR(-EIO);
1151 tty = driver->ops->lookup(driver, file, idx);
1153 tty = driver->ttys[idx];
1161 * tty_init_termios - helper for termios setup
1162 * @tty: the tty to set up
1164 * Initialise the termios structures for this tty. Thus runs under
1165 * the tty_mutex currently so we can be relaxed about ordering.
1168 void tty_init_termios(struct tty_struct *tty)
1170 struct ktermios *tp;
1171 int idx = tty->index;
1173 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1174 tty->termios = tty->driver->init_termios;
1176 /* Check for lazy saved data */
1177 tp = tty->driver->termios[idx];
1180 tty->termios.c_line = tty->driver->init_termios.c_line;
1182 tty->termios = tty->driver->init_termios;
1184 /* Compatibility until drivers always set this */
1185 tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
1186 tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
1188 EXPORT_SYMBOL_GPL(tty_init_termios);
1190 int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty)
1192 tty_init_termios(tty);
1193 tty_driver_kref_get(driver);
1195 driver->ttys[tty->index] = tty;
1198 EXPORT_SYMBOL_GPL(tty_standard_install);
1201 * tty_driver_install_tty() - install a tty entry in the driver
1202 * @driver: the driver for the tty
1205 * Install a tty object into the driver tables. The tty->index field
1206 * will be set by the time this is called. This method is responsible
1207 * for ensuring any need additional structures are allocated and
1210 * Locking: tty_mutex for now
1212 static int tty_driver_install_tty(struct tty_driver *driver,
1213 struct tty_struct *tty)
1215 return driver->ops->install ? driver->ops->install(driver, tty) :
1216 tty_standard_install(driver, tty);
1220 * tty_driver_remove_tty() - remove a tty from the driver tables
1221 * @driver: the driver for the tty
1222 * @idx: the minor number
1224 * Remvoe a tty object from the driver tables. The tty->index field
1225 * will be set by the time this is called.
1227 * Locking: tty_mutex for now
1229 static void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *tty)
1231 if (driver->ops->remove)
1232 driver->ops->remove(driver, tty);
1234 driver->ttys[tty->index] = NULL;
1238 * tty_reopen() - fast re-open of an open tty
1239 * @tty - the tty to open
1241 * Return 0 on success, -errno on error.
1242 * Re-opens on master ptys are not allowed and return -EIO.
1244 * Locking: Caller must hold tty_lock
1246 static int tty_reopen(struct tty_struct *tty)
1248 struct tty_driver *driver = tty->driver;
1250 if (driver->type == TTY_DRIVER_TYPE_PTY &&
1251 driver->subtype == PTY_TYPE_MASTER)
1257 if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
1263 return tty_ldisc_reinit(tty, tty->termios.c_line);
1269 * tty_init_dev - initialise a tty device
1270 * @driver: tty driver we are opening a device on
1271 * @idx: device index
1272 * @ret_tty: returned tty structure
1274 * Prepare a tty device. This may not be a "new" clean device but
1275 * could also be an active device. The pty drivers require special
1276 * handling because of this.
1279 * The function is called under the tty_mutex, which
1280 * protects us from the tty struct or driver itself going away.
1282 * On exit the tty device has the line discipline attached and
1283 * a reference count of 1. If a pair was created for pty/tty use
1284 * and the other was a pty master then it too has a reference count of 1.
1286 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1287 * failed open. The new code protects the open with a mutex, so it's
1288 * really quite straightforward. The mutex locking can probably be
1289 * relaxed for the (most common) case of reopening a tty.
1292 struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
1294 struct tty_struct *tty;
1298 * First time open is complex, especially for PTY devices.
1299 * This code guarantees that either everything succeeds and the
1300 * TTY is ready for operation, or else the table slots are vacated
1301 * and the allocated memory released. (Except that the termios
1305 if (!try_module_get(driver->owner))
1306 return ERR_PTR(-ENODEV);
1308 tty = alloc_tty_struct(driver, idx);
1311 goto err_module_put;
1315 retval = tty_driver_install_tty(driver, tty);
1320 tty->port = driver->ports[idx];
1322 WARN_RATELIMIT(!tty->port,
1323 "%s: %s driver does not set tty->port. This will crash the kernel later. Fix the driver!\n",
1324 __func__, tty->driver->name);
1326 tty->port->itty = tty;
1329 * Structures all installed ... call the ldisc open routines.
1330 * If we fail here just call release_tty to clean up. No need
1331 * to decrement the use counts, as release_tty doesn't care.
1333 retval = tty_ldisc_setup(tty, tty->link);
1335 goto err_release_tty;
1336 /* Return the tty locked so that it cannot vanish under the caller */
1341 free_tty_struct(tty);
1343 module_put(driver->owner);
1344 return ERR_PTR(retval);
1346 /* call the tty release_tty routine to clean out this slot */
1349 tty_info_ratelimited(tty, "ldisc open failed (%d), clearing slot %d\n",
1351 release_tty(tty, idx);
1352 return ERR_PTR(retval);
1355 static void tty_free_termios(struct tty_struct *tty)
1357 struct ktermios *tp;
1358 int idx = tty->index;
1360 /* If the port is going to reset then it has no termios to save */
1361 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1364 /* Stash the termios data */
1365 tp = tty->driver->termios[idx];
1367 tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
1370 tty->driver->termios[idx] = tp;
1376 * tty_flush_works - flush all works of a tty/pty pair
1377 * @tty: tty device to flush works for (or either end of a pty pair)
1379 * Sync flush all works belonging to @tty (and the 'other' tty).
1381 static void tty_flush_works(struct tty_struct *tty)
1383 flush_work(&tty->SAK_work);
1384 flush_work(&tty->hangup_work);
1386 flush_work(&tty->link->SAK_work);
1387 flush_work(&tty->link->hangup_work);
1392 * release_one_tty - release tty structure memory
1393 * @kref: kref of tty we are obliterating
1395 * Releases memory associated with a tty structure, and clears out the
1396 * driver table slots. This function is called when a device is no longer
1397 * in use. It also gets called when setup of a device fails.
1400 * takes the file list lock internally when working on the list
1401 * of ttys that the driver keeps.
1403 * This method gets called from a work queue so that the driver private
1404 * cleanup ops can sleep (needed for USB at least)
1406 static void release_one_tty(struct work_struct *work)
1408 struct tty_struct *tty =
1409 container_of(work, struct tty_struct, hangup_work);
1410 struct tty_driver *driver = tty->driver;
1411 struct module *owner = driver->owner;
1413 if (tty->ops->cleanup)
1414 tty->ops->cleanup(tty);
1417 tty_driver_kref_put(driver);
1420 spin_lock(&tty->files_lock);
1421 list_del_init(&tty->tty_files);
1422 spin_unlock(&tty->files_lock);
1425 put_pid(tty->session);
1426 free_tty_struct(tty);
1429 static void queue_release_one_tty(struct kref *kref)
1431 struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1433 /* The hangup queue is now free so we can reuse it rather than
1434 waste a chunk of memory for each port */
1435 INIT_WORK(&tty->hangup_work, release_one_tty);
1436 schedule_work(&tty->hangup_work);
1440 * tty_kref_put - release a tty kref
1443 * Release a reference to a tty device and if need be let the kref
1444 * layer destruct the object for us
1447 void tty_kref_put(struct tty_struct *tty)
1450 kref_put(&tty->kref, queue_release_one_tty);
1452 EXPORT_SYMBOL(tty_kref_put);
1455 * release_tty - release tty structure memory
1457 * Release both @tty and a possible linked partner (think pty pair),
1458 * and decrement the refcount of the backing module.
1462 * takes the file list lock internally when working on the list
1463 * of ttys that the driver keeps.
1466 static void release_tty(struct tty_struct *tty, int idx)
1468 /* This should always be true but check for the moment */
1469 WARN_ON(tty->index != idx);
1470 WARN_ON(!mutex_is_locked(&tty_mutex));
1471 if (tty->ops->shutdown)
1472 tty->ops->shutdown(tty);
1473 tty_free_termios(tty);
1474 tty_driver_remove_tty(tty->driver, tty);
1475 tty->port->itty = NULL;
1477 tty->link->port->itty = NULL;
1478 tty_buffer_cancel_work(tty->port);
1480 tty_kref_put(tty->link);
1485 * tty_release_checks - check a tty before real release
1486 * @tty: tty to check
1487 * @o_tty: link of @tty (if any)
1488 * @idx: index of the tty
1490 * Performs some paranoid checking before true release of the @tty.
1491 * This is a no-op unless TTY_PARANOIA_CHECK is defined.
1493 static int tty_release_checks(struct tty_struct *tty, int idx)
1495 #ifdef TTY_PARANOIA_CHECK
1496 if (idx < 0 || idx >= tty->driver->num) {
1497 tty_debug(tty, "bad idx %d\n", idx);
1501 /* not much to check for devpts */
1502 if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)
1505 if (tty != tty->driver->ttys[idx]) {
1506 tty_debug(tty, "bad driver table[%d] = %p\n",
1507 idx, tty->driver->ttys[idx]);
1510 if (tty->driver->other) {
1511 struct tty_struct *o_tty = tty->link;
1513 if (o_tty != tty->driver->other->ttys[idx]) {
1514 tty_debug(tty, "bad other table[%d] = %p\n",
1515 idx, tty->driver->other->ttys[idx]);
1518 if (o_tty->link != tty) {
1519 tty_debug(tty, "bad link = %p\n", o_tty->link);
1528 * tty_kclose - closes tty opened by tty_kopen
1531 * Performs the final steps to release and free a tty device. It is the
1532 * same as tty_release_struct except that it also resets TTY_PORT_KOPENED
1533 * flag on tty->port.
1535 void tty_kclose(struct tty_struct *tty)
1538 * Ask the line discipline code to release its structures
1540 tty_ldisc_release(tty);
1542 /* Wait for pending work before tty destruction commmences */
1543 tty_flush_works(tty);
1545 tty_debug_hangup(tty, "freeing structure\n");
1547 * The release_tty function takes care of the details of clearing
1548 * the slots and preserving the termios structure. The tty_unlock_pair
1549 * should be safe as we keep a kref while the tty is locked (so the
1550 * unlock never unlocks a freed tty).
1552 mutex_lock(&tty_mutex);
1553 tty_port_set_kopened(tty->port, 0);
1554 release_tty(tty, tty->index);
1555 mutex_unlock(&tty_mutex);
1557 EXPORT_SYMBOL_GPL(tty_kclose);
1560 * tty_release_struct - release a tty struct
1562 * @idx: index of the tty
1564 * Performs the final steps to release and free a tty device. It is
1565 * roughly the reverse of tty_init_dev.
1567 void tty_release_struct(struct tty_struct *tty, int idx)
1570 * Ask the line discipline code to release its structures
1572 tty_ldisc_release(tty);
1574 /* Wait for pending work before tty destruction commmences */
1575 tty_flush_works(tty);
1577 tty_debug_hangup(tty, "freeing structure\n");
1579 * The release_tty function takes care of the details of clearing
1580 * the slots and preserving the termios structure. The tty_unlock_pair
1581 * should be safe as we keep a kref while the tty is locked (so the
1582 * unlock never unlocks a freed tty).
1584 mutex_lock(&tty_mutex);
1585 release_tty(tty, idx);
1586 mutex_unlock(&tty_mutex);
1588 EXPORT_SYMBOL_GPL(tty_release_struct);
1591 * tty_release - vfs callback for close
1592 * @inode: inode of tty
1593 * @filp: file pointer for handle to tty
1595 * Called the last time each file handle is closed that references
1596 * this tty. There may however be several such references.
1599 * Takes bkl. See tty_release_dev
1601 * Even releasing the tty structures is a tricky business.. We have
1602 * to be very careful that the structures are all released at the
1603 * same time, as interrupts might otherwise get the wrong pointers.
1605 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1606 * lead to double frees or releasing memory still in use.
1609 int tty_release(struct inode *inode, struct file *filp)
1611 struct tty_struct *tty = file_tty(filp);
1612 struct tty_struct *o_tty = NULL;
1613 int do_sleep, final;
1618 if (tty_paranoia_check(tty, inode, __func__))
1622 check_tty_count(tty, __func__);
1624 __tty_fasync(-1, filp, 0);
1627 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1628 tty->driver->subtype == PTY_TYPE_MASTER)
1631 if (tty_release_checks(tty, idx)) {
1636 tty_debug_hangup(tty, "releasing (count=%d)\n", tty->count);
1638 if (tty->ops->close)
1639 tty->ops->close(tty, filp);
1641 /* If tty is pty master, lock the slave pty (stable lock order) */
1642 tty_lock_slave(o_tty);
1645 * Sanity check: if tty->count is going to zero, there shouldn't be
1646 * any waiters on tty->read_wait or tty->write_wait. We test the
1647 * wait queues and kick everyone out _before_ actually starting to
1648 * close. This ensures that we won't block while releasing the tty
1651 * The test for the o_tty closing is necessary, since the master and
1652 * slave sides may close in any order. If the slave side closes out
1653 * first, its count will be one, since the master side holds an open.
1654 * Thus this test wouldn't be triggered at the time the slave closed,
1660 if (tty->count <= 1) {
1661 if (waitqueue_active(&tty->read_wait)) {
1662 wake_up_poll(&tty->read_wait, POLLIN);
1665 if (waitqueue_active(&tty->write_wait)) {
1666 wake_up_poll(&tty->write_wait, POLLOUT);
1670 if (o_tty && o_tty->count <= 1) {
1671 if (waitqueue_active(&o_tty->read_wait)) {
1672 wake_up_poll(&o_tty->read_wait, POLLIN);
1675 if (waitqueue_active(&o_tty->write_wait)) {
1676 wake_up_poll(&o_tty->write_wait, POLLOUT);
1685 tty_warn(tty, "read/write wait queue active!\n");
1687 schedule_timeout_killable(timeout);
1688 if (timeout < 120 * HZ)
1689 timeout = 2 * timeout + 1;
1691 timeout = MAX_SCHEDULE_TIMEOUT;
1695 if (--o_tty->count < 0) {
1696 tty_warn(tty, "bad slave count (%d)\n", o_tty->count);
1700 if (--tty->count < 0) {
1701 tty_warn(tty, "bad tty->count (%d)\n", tty->count);
1706 * We've decremented tty->count, so we need to remove this file
1707 * descriptor off the tty->tty_files list; this serves two
1709 * - check_tty_count sees the correct number of file descriptors
1710 * associated with this tty.
1711 * - do_tty_hangup no longer sees this file descriptor as
1712 * something that needs to be handled for hangups.
1717 * Perform some housekeeping before deciding whether to return.
1719 * If _either_ side is closing, make sure there aren't any
1720 * processes that still think tty or o_tty is their controlling
1724 read_lock(&tasklist_lock);
1725 session_clear_tty(tty->session);
1727 session_clear_tty(o_tty->session);
1728 read_unlock(&tasklist_lock);
1731 /* check whether both sides are closing ... */
1732 final = !tty->count && !(o_tty && o_tty->count);
1734 tty_unlock_slave(o_tty);
1737 /* At this point, the tty->count == 0 should ensure a dead tty
1738 cannot be re-opened by a racing opener */
1743 tty_debug_hangup(tty, "final close\n");
1745 tty_release_struct(tty, idx);
1750 * tty_open_current_tty - get locked tty of current task
1751 * @device: device number
1752 * @filp: file pointer to tty
1753 * @return: locked tty of the current task iff @device is /dev/tty
1755 * Performs a re-open of the current task's controlling tty.
1757 * We cannot return driver and index like for the other nodes because
1758 * devpts will not work then. It expects inodes to be from devpts FS.
1760 static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
1762 struct tty_struct *tty;
1765 if (device != MKDEV(TTYAUX_MAJOR, 0))
1768 tty = get_current_tty();
1770 return ERR_PTR(-ENXIO);
1772 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1775 tty_kref_put(tty); /* safe to drop the kref now */
1777 retval = tty_reopen(tty);
1780 tty = ERR_PTR(retval);
1786 * tty_lookup_driver - lookup a tty driver for a given device file
1787 * @device: device number
1788 * @filp: file pointer to tty
1789 * @index: index for the device in the @return driver
1790 * @return: driver for this inode (with increased refcount)
1792 * If @return is not erroneous, the caller is responsible to decrement the
1793 * refcount by tty_driver_kref_put.
1795 * Locking: tty_mutex protects get_tty_driver
1797 static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
1800 struct tty_driver *driver;
1804 case MKDEV(TTY_MAJOR, 0): {
1805 extern struct tty_driver *console_driver;
1806 driver = tty_driver_kref_get(console_driver);
1807 *index = fg_console;
1811 case MKDEV(TTYAUX_MAJOR, 1): {
1812 struct tty_driver *console_driver = console_device(index);
1813 if (console_driver) {
1814 driver = tty_driver_kref_get(console_driver);
1815 if (driver && filp) {
1816 /* Don't let /dev/console block */
1817 filp->f_flags |= O_NONBLOCK;
1821 return ERR_PTR(-ENODEV);
1824 driver = get_tty_driver(device, index);
1826 return ERR_PTR(-ENODEV);
1833 * tty_kopen - open a tty device for kernel
1834 * @device: dev_t of device to open
1836 * Opens tty exclusively for kernel. Performs the driver lookup,
1837 * makes sure it's not already opened and performs the first-time
1838 * tty initialization.
1840 * Returns the locked initialized &tty_struct
1842 * Claims the global tty_mutex to serialize:
1843 * - concurrent first-time tty initialization
1844 * - concurrent tty driver removal w/ lookup
1845 * - concurrent tty removal from driver table
1847 struct tty_struct *tty_kopen(dev_t device)
1849 struct tty_struct *tty;
1850 struct tty_driver *driver = NULL;
1853 mutex_lock(&tty_mutex);
1854 driver = tty_lookup_driver(device, NULL, &index);
1855 if (IS_ERR(driver)) {
1856 mutex_unlock(&tty_mutex);
1857 return ERR_CAST(driver);
1860 /* check whether we're reopening an existing tty */
1861 tty = tty_driver_lookup_tty(driver, NULL, index);
1866 /* drop kref from tty_driver_lookup_tty() */
1868 tty = ERR_PTR(-EBUSY);
1869 } else { /* tty_init_dev returns tty with the tty_lock held */
1870 tty = tty_init_dev(driver, index);
1873 tty_port_set_kopened(tty->port, 1);
1876 mutex_unlock(&tty_mutex);
1877 tty_driver_kref_put(driver);
1880 EXPORT_SYMBOL_GPL(tty_kopen);
1883 * tty_open_by_driver - open a tty device
1884 * @device: dev_t of device to open
1885 * @inode: inode of device file
1886 * @filp: file pointer to tty
1888 * Performs the driver lookup, checks for a reopen, or otherwise
1889 * performs the first-time tty initialization.
1891 * Returns the locked initialized or re-opened &tty_struct
1893 * Claims the global tty_mutex to serialize:
1894 * - concurrent first-time tty initialization
1895 * - concurrent tty driver removal w/ lookup
1896 * - concurrent tty removal from driver table
1898 static struct tty_struct *tty_open_by_driver(dev_t device, struct inode *inode,
1901 struct tty_struct *tty;
1902 struct tty_driver *driver = NULL;
1906 mutex_lock(&tty_mutex);
1907 driver = tty_lookup_driver(device, filp, &index);
1908 if (IS_ERR(driver)) {
1909 mutex_unlock(&tty_mutex);
1910 return ERR_CAST(driver);
1913 /* check whether we're reopening an existing tty */
1914 tty = tty_driver_lookup_tty(driver, filp, index);
1916 mutex_unlock(&tty_mutex);
1921 if (tty_port_kopened(tty->port)) {
1923 mutex_unlock(&tty_mutex);
1924 tty = ERR_PTR(-EBUSY);
1927 mutex_unlock(&tty_mutex);
1928 retval = tty_lock_interruptible(tty);
1929 tty_kref_put(tty); /* drop kref from tty_driver_lookup_tty() */
1931 if (retval == -EINTR)
1932 retval = -ERESTARTSYS;
1933 tty = ERR_PTR(retval);
1936 retval = tty_reopen(tty);
1939 tty = ERR_PTR(retval);
1941 } else { /* Returns with the tty_lock held for now */
1942 tty = tty_init_dev(driver, index);
1943 mutex_unlock(&tty_mutex);
1946 tty_driver_kref_put(driver);
1951 * tty_open - open a tty device
1952 * @inode: inode of device file
1953 * @filp: file pointer to tty
1955 * tty_open and tty_release keep up the tty count that contains the
1956 * number of opens done on a tty. We cannot use the inode-count, as
1957 * different inodes might point to the same tty.
1959 * Open-counting is needed for pty masters, as well as for keeping
1960 * track of serial lines: DTR is dropped when the last close happens.
1961 * (This is not done solely through tty->count, now. - Ted 1/27/92)
1963 * The termios state of a pty is reset on first open so that
1964 * settings don't persist across reuse.
1966 * Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.
1967 * tty->count should protect the rest.
1968 * ->siglock protects ->signal/->sighand
1970 * Note: the tty_unlock/lock cases without a ref are only safe due to
1974 static int tty_open(struct inode *inode, struct file *filp)
1976 struct tty_struct *tty;
1978 dev_t device = inode->i_rdev;
1979 unsigned saved_flags = filp->f_flags;
1981 nonseekable_open(inode, filp);
1984 retval = tty_alloc_file(filp);
1988 tty = tty_open_current_tty(device, filp);
1990 tty = tty_open_by_driver(device, inode, filp);
1993 tty_free_file(filp);
1994 retval = PTR_ERR(tty);
1995 if (retval != -EAGAIN || signal_pending(current))
2001 tty_add_file(tty, filp);
2003 check_tty_count(tty, __func__);
2004 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
2007 retval = tty->ops->open(tty, filp);
2010 filp->f_flags = saved_flags;
2013 tty_debug_hangup(tty, "open error %d, releasing\n", retval);
2015 tty_unlock(tty); /* need to call tty_release without BTM */
2016 tty_release(inode, filp);
2017 if (retval != -ERESTARTSYS)
2020 if (signal_pending(current))
2025 * Need to reset f_op in case a hangup happened.
2027 if (tty_hung_up_p(filp))
2028 filp->f_op = &tty_fops;
2031 clear_bit(TTY_HUPPED, &tty->flags);
2033 noctty = (filp->f_flags & O_NOCTTY) ||
2034 (IS_ENABLED(CONFIG_VT) && device == MKDEV(TTY_MAJOR, 0)) ||
2035 device == MKDEV(TTYAUX_MAJOR, 1) ||
2036 (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2037 tty->driver->subtype == PTY_TYPE_MASTER);
2039 tty_open_proc_set_tty(filp, tty);
2047 * tty_poll - check tty status
2048 * @filp: file being polled
2049 * @wait: poll wait structures to update
2051 * Call the line discipline polling method to obtain the poll
2052 * status of the device.
2054 * Locking: locks called line discipline but ldisc poll method
2055 * may be re-entered freely by other callers.
2058 static unsigned int tty_poll(struct file *filp, poll_table *wait)
2060 struct tty_struct *tty = file_tty(filp);
2061 struct tty_ldisc *ld;
2064 if (tty_paranoia_check(tty, file_inode(filp), "tty_poll"))
2067 ld = tty_ldisc_ref_wait(tty);
2069 return hung_up_tty_poll(filp, wait);
2071 ret = ld->ops->poll(tty, filp, wait);
2072 tty_ldisc_deref(ld);
2076 static int __tty_fasync(int fd, struct file *filp, int on)
2078 struct tty_struct *tty = file_tty(filp);
2079 unsigned long flags;
2082 if (tty_paranoia_check(tty, file_inode(filp), "tty_fasync"))
2085 retval = fasync_helper(fd, filp, on, &tty->fasync);
2093 spin_lock_irqsave(&tty->ctrl_lock, flags);
2096 type = PIDTYPE_PGID;
2098 pid = task_pid(current);
2102 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2103 __f_setown(filp, pid, type, 0);
2111 static int tty_fasync(int fd, struct file *filp, int on)
2113 struct tty_struct *tty = file_tty(filp);
2114 int retval = -ENOTTY;
2117 if (!tty_hung_up_p(filp))
2118 retval = __tty_fasync(fd, filp, on);
2125 * tiocsti - fake input character
2126 * @tty: tty to fake input into
2127 * @p: pointer to character
2129 * Fake input to a tty device. Does the necessary locking and
2132 * FIXME: does not honour flow control ??
2135 * Called functions take tty_ldiscs_lock
2136 * current->signal->tty check is safe without locks
2138 * FIXME: may race normal receive processing
2141 static int tiocsti(struct tty_struct *tty, char __user *p)
2144 struct tty_ldisc *ld;
2146 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2148 if (get_user(ch, p))
2150 tty_audit_tiocsti(tty, ch);
2151 ld = tty_ldisc_ref_wait(tty);
2154 ld->ops->receive_buf(tty, &ch, &mbz, 1);
2155 tty_ldisc_deref(ld);
2160 * tiocgwinsz - implement window query ioctl
2162 * @arg: user buffer for result
2164 * Copies the kernel idea of the window size into the user buffer.
2166 * Locking: tty->winsize_mutex is taken to ensure the winsize data
2170 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2174 mutex_lock(&tty->winsize_mutex);
2175 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2176 mutex_unlock(&tty->winsize_mutex);
2178 return err ? -EFAULT: 0;
2182 * tty_do_resize - resize event
2183 * @tty: tty being resized
2184 * @rows: rows (character)
2185 * @cols: cols (character)
2187 * Update the termios variables and send the necessary signals to
2188 * peform a terminal resize correctly
2191 int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
2196 mutex_lock(&tty->winsize_mutex);
2197 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
2200 /* Signal the foreground process group */
2201 pgrp = tty_get_pgrp(tty);
2203 kill_pgrp(pgrp, SIGWINCH, 1);
2208 mutex_unlock(&tty->winsize_mutex);
2211 EXPORT_SYMBOL(tty_do_resize);
2214 * tiocswinsz - implement window size set ioctl
2215 * @tty; tty side of tty
2216 * @arg: user buffer for result
2218 * Copies the user idea of the window size to the kernel. Traditionally
2219 * this is just advisory information but for the Linux console it
2220 * actually has driver level meaning and triggers a VC resize.
2223 * Driver dependent. The default do_resize method takes the
2224 * tty termios mutex and ctrl_lock. The console takes its own lock
2225 * then calls into the default method.
2228 static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
2230 struct winsize tmp_ws;
2231 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2234 if (tty->ops->resize)
2235 return tty->ops->resize(tty, &tmp_ws);
2237 return tty_do_resize(tty, &tmp_ws);
2241 * tioccons - allow admin to move logical console
2242 * @file: the file to become console
2244 * Allow the administrator to move the redirected console device
2246 * Locking: uses redirect_lock to guard the redirect information
2249 static int tioccons(struct file *file)
2251 if (!capable(CAP_SYS_ADMIN))
2253 if (file->f_op->write == redirected_tty_write) {
2255 spin_lock(&redirect_lock);
2258 spin_unlock(&redirect_lock);
2263 spin_lock(&redirect_lock);
2265 spin_unlock(&redirect_lock);
2268 redirect = get_file(file);
2269 spin_unlock(&redirect_lock);
2274 * fionbio - non blocking ioctl
2275 * @file: file to set blocking value
2276 * @p: user parameter
2278 * Historical tty interfaces had a blocking control ioctl before
2279 * the generic functionality existed. This piece of history is preserved
2280 * in the expected tty API of posix OS's.
2282 * Locking: none, the open file handle ensures it won't go away.
2285 static int fionbio(struct file *file, int __user *p)
2289 if (get_user(nonblock, p))
2292 spin_lock(&file->f_lock);
2294 file->f_flags |= O_NONBLOCK;
2296 file->f_flags &= ~O_NONBLOCK;
2297 spin_unlock(&file->f_lock);
2302 * tiocsetd - set line discipline
2304 * @p: pointer to user data
2306 * Set the line discipline according to user request.
2308 * Locking: see tty_set_ldisc, this function is just a helper
2311 static int tiocsetd(struct tty_struct *tty, int __user *p)
2316 if (get_user(disc, p))
2319 ret = tty_set_ldisc(tty, disc);
2325 * tiocgetd - get line discipline
2327 * @p: pointer to user data
2329 * Retrieves the line discipline id directly from the ldisc.
2331 * Locking: waits for ldisc reference (in case the line discipline
2332 * is changing or the tty is being hungup)
2335 static int tiocgetd(struct tty_struct *tty, int __user *p)
2337 struct tty_ldisc *ld;
2340 ld = tty_ldisc_ref_wait(tty);
2343 ret = put_user(ld->ops->num, p);
2344 tty_ldisc_deref(ld);
2349 * send_break - performed time break
2350 * @tty: device to break on
2351 * @duration: timeout in mS
2353 * Perform a timed break on hardware that lacks its own driver level
2354 * timed break functionality.
2357 * atomic_write_lock serializes
2361 static int send_break(struct tty_struct *tty, unsigned int duration)
2365 if (tty->ops->break_ctl == NULL)
2368 if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2369 retval = tty->ops->break_ctl(tty, duration);
2371 /* Do the work ourselves */
2372 if (tty_write_lock(tty, 0) < 0)
2374 retval = tty->ops->break_ctl(tty, -1);
2377 if (!signal_pending(current))
2378 msleep_interruptible(duration);
2379 retval = tty->ops->break_ctl(tty, 0);
2381 tty_write_unlock(tty);
2382 if (signal_pending(current))
2389 * tty_tiocmget - get modem status
2391 * @file: user file pointer
2392 * @p: pointer to result
2394 * Obtain the modem status bits from the tty driver if the feature
2395 * is supported. Return -EINVAL if it is not available.
2397 * Locking: none (up to the driver)
2400 static int tty_tiocmget(struct tty_struct *tty, int __user *p)
2402 int retval = -EINVAL;
2404 if (tty->ops->tiocmget) {
2405 retval = tty->ops->tiocmget(tty);
2408 retval = put_user(retval, p);
2414 * tty_tiocmset - set modem status
2416 * @cmd: command - clear bits, set bits or set all
2417 * @p: pointer to desired bits
2419 * Set the modem status bits from the tty driver if the feature
2420 * is supported. Return -EINVAL if it is not available.
2422 * Locking: none (up to the driver)
2425 static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
2429 unsigned int set, clear, val;
2431 if (tty->ops->tiocmset == NULL)
2434 retval = get_user(val, p);
2450 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2451 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2452 return tty->ops->tiocmset(tty, set, clear);
2455 static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
2457 int retval = -EINVAL;
2458 struct serial_icounter_struct icount;
2459 memset(&icount, 0, sizeof(icount));
2460 if (tty->ops->get_icount)
2461 retval = tty->ops->get_icount(tty, &icount);
2464 if (copy_to_user(arg, &icount, sizeof(icount)))
2469 static void tty_warn_deprecated_flags(struct serial_struct __user *ss)
2471 static DEFINE_RATELIMIT_STATE(depr_flags,
2472 DEFAULT_RATELIMIT_INTERVAL,
2473 DEFAULT_RATELIMIT_BURST);
2474 char comm[TASK_COMM_LEN];
2477 if (get_user(flags, &ss->flags))
2480 flags &= ASYNC_DEPRECATED;
2482 if (flags && __ratelimit(&depr_flags))
2483 pr_warn("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
2484 __func__, get_task_comm(comm, current), flags);
2488 * if pty, return the slave side (real_tty)
2489 * otherwise, return self
2491 static struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
2493 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2494 tty->driver->subtype == PTY_TYPE_MASTER)
2500 * Split this up, as gcc can choke on it otherwise..
2502 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2504 struct tty_struct *tty = file_tty(file);
2505 struct tty_struct *real_tty;
2506 void __user *p = (void __user *)arg;
2508 struct tty_ldisc *ld;
2510 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2513 real_tty = tty_pair_get_tty(tty);
2516 * Factor out some common prep work
2524 retval = tty_check_change(tty);
2527 if (cmd != TIOCCBRK) {
2528 tty_wait_until_sent(tty, 0);
2529 if (signal_pending(current))
2540 return tiocsti(tty, p);
2542 return tiocgwinsz(real_tty, p);
2544 return tiocswinsz(real_tty, p);
2546 return real_tty != tty ? -EINVAL : tioccons(file);
2548 return fionbio(file, p);
2550 set_bit(TTY_EXCLUSIVE, &tty->flags);
2553 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2557 int excl = test_bit(TTY_EXCLUSIVE, &tty->flags);
2558 return put_user(excl, (int __user *)p);
2561 return tiocgetd(tty, p);
2563 return tiocsetd(tty, p);
2565 if (!capable(CAP_SYS_ADMIN))
2571 unsigned int ret = new_encode_dev(tty_devnum(real_tty));
2572 return put_user(ret, (unsigned int __user *)p);
2577 case TIOCSBRK: /* Turn break on, unconditionally */
2578 if (tty->ops->break_ctl)
2579 return tty->ops->break_ctl(tty, -1);
2581 case TIOCCBRK: /* Turn break off, unconditionally */
2582 if (tty->ops->break_ctl)
2583 return tty->ops->break_ctl(tty, 0);
2585 case TCSBRK: /* SVID version: non-zero arg --> no break */
2586 /* non-zero arg means wait for all output data
2587 * to be sent (performed above) but don't send break.
2588 * This is used by the tcdrain() termios function.
2591 return send_break(tty, 250);
2593 case TCSBRKP: /* support for POSIX tcsendbreak() */
2594 return send_break(tty, arg ? arg*100 : 250);
2597 return tty_tiocmget(tty, p);
2601 return tty_tiocmset(tty, cmd, p);
2603 retval = tty_tiocgicount(tty, p);
2604 /* For the moment allow fall through to the old method */
2605 if (retval != -EINVAL)
2612 /* flush tty buffer and allow ldisc to process ioctl */
2613 tty_buffer_flush(tty, NULL);
2618 tty_warn_deprecated_flags(p);
2621 /* Special because the struct file is needed */
2622 return ptm_open_peer(file, tty, (int)arg);
2624 retval = tty_jobctrl_ioctl(tty, real_tty, file, cmd, arg);
2625 if (retval != -ENOIOCTLCMD)
2628 if (tty->ops->ioctl) {
2629 retval = tty->ops->ioctl(tty, cmd, arg);
2630 if (retval != -ENOIOCTLCMD)
2633 ld = tty_ldisc_ref_wait(tty);
2635 return hung_up_tty_ioctl(file, cmd, arg);
2637 if (ld->ops->ioctl) {
2638 retval = ld->ops->ioctl(tty, file, cmd, arg);
2639 if (retval == -ENOIOCTLCMD)
2642 tty_ldisc_deref(ld);
2646 #ifdef CONFIG_COMPAT
2647 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2650 struct tty_struct *tty = file_tty(file);
2651 struct tty_ldisc *ld;
2652 int retval = -ENOIOCTLCMD;
2654 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2657 if (tty->ops->compat_ioctl) {
2658 retval = tty->ops->compat_ioctl(tty, cmd, arg);
2659 if (retval != -ENOIOCTLCMD)
2663 ld = tty_ldisc_ref_wait(tty);
2665 return hung_up_tty_compat_ioctl(file, cmd, arg);
2666 if (ld->ops->compat_ioctl)
2667 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
2669 retval = n_tty_compat_ioctl_helper(tty, file, cmd, arg);
2670 tty_ldisc_deref(ld);
2676 static int this_tty(const void *t, struct file *file, unsigned fd)
2678 if (likely(file->f_op->read != tty_read))
2680 return file_tty(file) != t ? 0 : fd + 1;
2684 * This implements the "Secure Attention Key" --- the idea is to
2685 * prevent trojan horses by killing all processes associated with this
2686 * tty when the user hits the "Secure Attention Key". Required for
2687 * super-paranoid applications --- see the Orange Book for more details.
2689 * This code could be nicer; ideally it should send a HUP, wait a few
2690 * seconds, then send a INT, and then a KILL signal. But you then
2691 * have to coordinate with the init process, since all processes associated
2692 * with the current tty must be dead before the new getty is allowed
2695 * Now, if it would be correct ;-/ The current code has a nasty hole -
2696 * it doesn't catch files in flight. We may send the descriptor to ourselves
2697 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
2699 * Nasty bug: do_SAK is being called in interrupt context. This can
2700 * deadlock. We punt it up to process context. AKPM - 16Mar2001
2702 void __do_SAK(struct tty_struct *tty)
2707 struct task_struct *g, *p;
2708 struct pid *session;
2713 session = tty->session;
2715 tty_ldisc_flush(tty);
2717 tty_driver_flush_buffer(tty);
2719 read_lock(&tasklist_lock);
2720 /* Kill the entire session */
2721 do_each_pid_task(session, PIDTYPE_SID, p) {
2722 tty_notice(tty, "SAK: killed process %d (%s): by session\n",
2723 task_pid_nr(p), p->comm);
2724 send_sig(SIGKILL, p, 1);
2725 } while_each_pid_task(session, PIDTYPE_SID, p);
2727 /* Now kill any processes that happen to have the tty open */
2728 do_each_thread(g, p) {
2729 if (p->signal->tty == tty) {
2730 tty_notice(tty, "SAK: killed process %d (%s): by controlling tty\n",
2731 task_pid_nr(p), p->comm);
2732 send_sig(SIGKILL, p, 1);
2736 i = iterate_fd(p->files, 0, this_tty, tty);
2738 tty_notice(tty, "SAK: killed process %d (%s): by fd#%d\n",
2739 task_pid_nr(p), p->comm, i - 1);
2740 force_sig(SIGKILL, p);
2743 } while_each_thread(g, p);
2744 read_unlock(&tasklist_lock);
2748 static void do_SAK_work(struct work_struct *work)
2750 struct tty_struct *tty =
2751 container_of(work, struct tty_struct, SAK_work);
2756 * The tq handling here is a little racy - tty->SAK_work may already be queued.
2757 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
2758 * the values which we write to it will be identical to the values which it
2759 * already has. --akpm
2761 void do_SAK(struct tty_struct *tty)
2765 schedule_work(&tty->SAK_work);
2768 EXPORT_SYMBOL(do_SAK);
2770 static int dev_match_devt(struct device *dev, const void *data)
2772 const dev_t *devt = data;
2773 return dev->devt == *devt;
2776 /* Must put_device() after it's unused! */
2777 static struct device *tty_get_device(struct tty_struct *tty)
2779 dev_t devt = tty_devnum(tty);
2780 return class_find_device(tty_class, NULL, &devt, dev_match_devt);
2787 * This subroutine allocates and initializes a tty structure.
2789 * Locking: none - tty in question is not exposed at this point
2792 struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
2794 struct tty_struct *tty;
2796 tty = kzalloc(sizeof(*tty), GFP_KERNEL);
2800 kref_init(&tty->kref);
2801 tty->magic = TTY_MAGIC;
2802 tty_ldisc_init(tty);
2803 tty->session = NULL;
2805 mutex_init(&tty->legacy_mutex);
2806 mutex_init(&tty->throttle_mutex);
2807 init_rwsem(&tty->termios_rwsem);
2808 mutex_init(&tty->winsize_mutex);
2809 init_ldsem(&tty->ldisc_sem);
2810 init_waitqueue_head(&tty->write_wait);
2811 init_waitqueue_head(&tty->read_wait);
2812 INIT_WORK(&tty->hangup_work, do_tty_hangup);
2813 mutex_init(&tty->atomic_write_lock);
2814 spin_lock_init(&tty->ctrl_lock);
2815 spin_lock_init(&tty->flow_lock);
2816 spin_lock_init(&tty->files_lock);
2817 INIT_LIST_HEAD(&tty->tty_files);
2818 INIT_WORK(&tty->SAK_work, do_SAK_work);
2820 tty->driver = driver;
2821 tty->ops = driver->ops;
2823 tty_line_name(driver, idx, tty->name);
2824 tty->dev = tty_get_device(tty);
2830 * tty_put_char - write one character to a tty
2834 * Write one byte to the tty using the provided put_char method
2835 * if present. Returns the number of characters successfully output.
2837 * Note: the specific put_char operation in the driver layer may go
2838 * away soon. Don't call it directly, use this method
2841 int tty_put_char(struct tty_struct *tty, unsigned char ch)
2843 if (tty->ops->put_char)
2844 return tty->ops->put_char(tty, ch);
2845 return tty->ops->write(tty, &ch, 1);
2847 EXPORT_SYMBOL_GPL(tty_put_char);
2849 struct class *tty_class;
2851 static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
2852 unsigned int index, unsigned int count)
2856 /* init here, since reused cdevs cause crashes */
2857 driver->cdevs[index] = cdev_alloc();
2858 if (!driver->cdevs[index])
2860 driver->cdevs[index]->ops = &tty_fops;
2861 driver->cdevs[index]->owner = driver->owner;
2862 err = cdev_add(driver->cdevs[index], dev, count);
2864 kobject_put(&driver->cdevs[index]->kobj);
2869 * tty_register_device - register a tty device
2870 * @driver: the tty driver that describes the tty device
2871 * @index: the index in the tty driver for this tty device
2872 * @device: a struct device that is associated with this tty device.
2873 * This field is optional, if there is no known struct device
2874 * for this tty device it can be set to NULL safely.
2876 * Returns a pointer to the struct device for this tty device
2877 * (or ERR_PTR(-EFOO) on error).
2879 * This call is required to be made to register an individual tty device
2880 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
2881 * that bit is not set, this function should not be called by a tty
2887 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
2888 struct device *device)
2890 return tty_register_device_attr(driver, index, device, NULL, NULL);
2892 EXPORT_SYMBOL(tty_register_device);
2894 static void tty_device_create_release(struct device *dev)
2896 dev_dbg(dev, "releasing...\n");
2901 * tty_register_device_attr - register a tty device
2902 * @driver: the tty driver that describes the tty device
2903 * @index: the index in the tty driver for this tty device
2904 * @device: a struct device that is associated with this tty device.
2905 * This field is optional, if there is no known struct device
2906 * for this tty device it can be set to NULL safely.
2907 * @drvdata: Driver data to be set to device.
2908 * @attr_grp: Attribute group to be set on device.
2910 * Returns a pointer to the struct device for this tty device
2911 * (or ERR_PTR(-EFOO) on error).
2913 * This call is required to be made to register an individual tty device
2914 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
2915 * that bit is not set, this function should not be called by a tty
2920 struct device *tty_register_device_attr(struct tty_driver *driver,
2921 unsigned index, struct device *device,
2923 const struct attribute_group **attr_grp)
2926 dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
2927 struct ktermios *tp;
2931 if (index >= driver->num) {
2932 pr_err("%s: Attempt to register invalid tty line number (%d)\n",
2933 driver->name, index);
2934 return ERR_PTR(-EINVAL);
2937 if (driver->type == TTY_DRIVER_TYPE_PTY)
2938 pty_line_name(driver, index, name);
2940 tty_line_name(driver, index, name);
2942 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
2944 return ERR_PTR(-ENOMEM);
2947 dev->class = tty_class;
2948 dev->parent = device;
2949 dev->release = tty_device_create_release;
2950 dev_set_name(dev, "%s", name);
2951 dev->groups = attr_grp;
2952 dev_set_drvdata(dev, drvdata);
2954 dev_set_uevent_suppress(dev, 1);
2956 retval = device_register(dev);
2960 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
2962 * Free any saved termios data so that the termios state is
2963 * reset when reusing a minor number.
2965 tp = driver->termios[index];
2967 driver->termios[index] = NULL;
2971 retval = tty_cdev_add(driver, devt, index, 1);
2976 dev_set_uevent_suppress(dev, 0);
2977 kobject_uevent(&dev->kobj, KOBJ_ADD);
2986 return ERR_PTR(retval);
2988 EXPORT_SYMBOL_GPL(tty_register_device_attr);
2991 * tty_unregister_device - unregister a tty device
2992 * @driver: the tty driver that describes the tty device
2993 * @index: the index in the tty driver for this tty device
2995 * If a tty device is registered with a call to tty_register_device() then
2996 * this function must be called when the tty device is gone.
3001 void tty_unregister_device(struct tty_driver *driver, unsigned index)
3003 device_destroy(tty_class,
3004 MKDEV(driver->major, driver->minor_start) + index);
3005 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3006 cdev_del(driver->cdevs[index]);
3007 driver->cdevs[index] = NULL;
3010 EXPORT_SYMBOL(tty_unregister_device);
3013 * __tty_alloc_driver -- allocate tty driver
3014 * @lines: count of lines this driver can handle at most
3015 * @owner: module which is responsible for this driver
3016 * @flags: some of TTY_DRIVER_* flags, will be set in driver->flags
3018 * This should not be called directly, some of the provided macros should be
3019 * used instead. Use IS_ERR and friends on @retval.
3021 struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
3022 unsigned long flags)
3024 struct tty_driver *driver;
3025 unsigned int cdevs = 1;
3028 if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
3029 return ERR_PTR(-EINVAL);
3031 driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
3033 return ERR_PTR(-ENOMEM);
3035 kref_init(&driver->kref);
3036 driver->magic = TTY_DRIVER_MAGIC;
3037 driver->num = lines;
3038 driver->owner = owner;
3039 driver->flags = flags;
3041 if (!(flags & TTY_DRIVER_DEVPTS_MEM)) {
3042 driver->ttys = kcalloc(lines, sizeof(*driver->ttys),
3044 driver->termios = kcalloc(lines, sizeof(*driver->termios),
3046 if (!driver->ttys || !driver->termios) {
3052 if (!(flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3053 driver->ports = kcalloc(lines, sizeof(*driver->ports),
3055 if (!driver->ports) {
3062 driver->cdevs = kcalloc(cdevs, sizeof(*driver->cdevs), GFP_KERNEL);
3063 if (!driver->cdevs) {
3070 kfree(driver->ports);
3071 kfree(driver->ttys);
3072 kfree(driver->termios);
3073 kfree(driver->cdevs);
3075 return ERR_PTR(err);
3077 EXPORT_SYMBOL(__tty_alloc_driver);
3079 static void destruct_tty_driver(struct kref *kref)
3081 struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
3083 struct ktermios *tp;
3085 if (driver->flags & TTY_DRIVER_INSTALLED) {
3086 for (i = 0; i < driver->num; i++) {
3087 tp = driver->termios[i];
3089 driver->termios[i] = NULL;
3092 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3093 tty_unregister_device(driver, i);
3095 proc_tty_unregister_driver(driver);
3096 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
3097 cdev_del(driver->cdevs[0]);
3099 kfree(driver->cdevs);
3100 kfree(driver->ports);
3101 kfree(driver->termios);
3102 kfree(driver->ttys);
3106 void tty_driver_kref_put(struct tty_driver *driver)
3108 kref_put(&driver->kref, destruct_tty_driver);
3110 EXPORT_SYMBOL(tty_driver_kref_put);
3112 void tty_set_operations(struct tty_driver *driver,
3113 const struct tty_operations *op)
3117 EXPORT_SYMBOL(tty_set_operations);
3119 void put_tty_driver(struct tty_driver *d)
3121 tty_driver_kref_put(d);
3123 EXPORT_SYMBOL(put_tty_driver);
3126 * Called by a tty driver to register itself.
3128 int tty_register_driver(struct tty_driver *driver)
3135 if (!driver->major) {
3136 error = alloc_chrdev_region(&dev, driver->minor_start,
3137 driver->num, driver->name);
3139 driver->major = MAJOR(dev);
3140 driver->minor_start = MINOR(dev);
3143 dev = MKDEV(driver->major, driver->minor_start);
3144 error = register_chrdev_region(dev, driver->num, driver->name);
3149 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) {
3150 error = tty_cdev_add(driver, dev, 0, driver->num);
3152 goto err_unreg_char;
3155 mutex_lock(&tty_mutex);
3156 list_add(&driver->tty_drivers, &tty_drivers);
3157 mutex_unlock(&tty_mutex);
3159 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
3160 for (i = 0; i < driver->num; i++) {
3161 d = tty_register_device(driver, i, NULL);
3164 goto err_unreg_devs;
3168 proc_tty_register_driver(driver);
3169 driver->flags |= TTY_DRIVER_INSTALLED;
3173 for (i--; i >= 0; i--)
3174 tty_unregister_device(driver, i);
3176 mutex_lock(&tty_mutex);
3177 list_del(&driver->tty_drivers);
3178 mutex_unlock(&tty_mutex);
3181 unregister_chrdev_region(dev, driver->num);
3185 EXPORT_SYMBOL(tty_register_driver);
3188 * Called by a tty driver to unregister itself.
3190 int tty_unregister_driver(struct tty_driver *driver)
3194 if (driver->refcount)
3197 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3199 mutex_lock(&tty_mutex);
3200 list_del(&driver->tty_drivers);
3201 mutex_unlock(&tty_mutex);
3205 EXPORT_SYMBOL(tty_unregister_driver);
3207 dev_t tty_devnum(struct tty_struct *tty)
3209 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3211 EXPORT_SYMBOL(tty_devnum);
3213 void tty_default_fops(struct file_operations *fops)
3218 static char *tty_devnode(struct device *dev, umode_t *mode)
3222 if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
3223 dev->devt == MKDEV(TTYAUX_MAJOR, 2))
3228 static int __init tty_class_init(void)
3230 tty_class = class_create(THIS_MODULE, "tty");
3231 if (IS_ERR(tty_class))
3232 return PTR_ERR(tty_class);
3233 tty_class->devnode = tty_devnode;
3237 postcore_initcall(tty_class_init);
3239 /* 3/2004 jmc: why do these devices exist? */
3240 static struct cdev tty_cdev, console_cdev;
3242 static ssize_t show_cons_active(struct device *dev,
3243 struct device_attribute *attr, char *buf)
3245 struct console *cs[16];
3251 for_each_console(c) {
3256 if ((c->flags & CON_ENABLED) == 0)
3259 if (i >= ARRAY_SIZE(cs))
3263 int index = cs[i]->index;
3264 struct tty_driver *drv = cs[i]->device(cs[i], &index);
3266 /* don't resolve tty0 as some programs depend on it */
3267 if (drv && (cs[i]->index > 0 || drv->major != TTY_MAJOR))
3268 count += tty_line_name(drv, index, buf + count);
3270 count += sprintf(buf + count, "%s%d",
3271 cs[i]->name, cs[i]->index);
3273 count += sprintf(buf + count, "%c", i ? ' ':'\n');
3279 static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
3281 static struct attribute *cons_dev_attrs[] = {
3282 &dev_attr_active.attr,
3286 ATTRIBUTE_GROUPS(cons_dev);
3288 static struct device *consdev;
3290 void console_sysfs_notify(void)
3293 sysfs_notify(&consdev->kobj, NULL, "active");
3297 * Ok, now we can initialize the rest of the tty devices and can count
3298 * on memory allocations, interrupts etc..
3300 int __init tty_init(void)
3302 cdev_init(&tty_cdev, &tty_fops);
3303 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3304 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3305 panic("Couldn't register /dev/tty driver\n");
3306 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
3308 cdev_init(&console_cdev, &console_fops);
3309 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3310 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3311 panic("Couldn't register /dev/console driver\n");
3312 consdev = device_create_with_groups(tty_class, NULL,
3313 MKDEV(TTYAUX_MAJOR, 1), NULL,
3314 cons_dev_groups, "console");
3315 if (IS_ERR(consdev))
3319 vty_init(&console_fops);