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 (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;
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, EPOLLOUT);
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)) {
590 * Some console devices aren't actually hung up for technical and
591 * historical reasons, which can lead to indefinite interruptible
592 * sleep in n_tty_read(). The following explicitly tells
593 * n_tty_read() to abort readers.
595 set_bit(TTY_HUPPING, &tty->flags);
597 /* inuse_filps is protected by the single tty lock,
598 this really needs to change if we want to flush the
599 workqueue with the lock held */
600 check_tty_count(tty, "tty_hangup");
602 spin_lock(&tty->files_lock);
603 /* This breaks for file handles being sent over AF_UNIX sockets ? */
604 list_for_each_entry(priv, &tty->tty_files, list) {
606 if (filp->f_op->write == redirected_tty_write)
608 if (filp->f_op->write != tty_write)
611 __tty_fasync(-1, filp, 0); /* can't block */
612 filp->f_op = &hung_up_tty_fops;
614 spin_unlock(&tty->files_lock);
616 refs = tty_signal_session_leader(tty, exit_session);
617 /* Account for the p->signal references we killed */
621 tty_ldisc_hangup(tty, cons_filp != NULL);
623 spin_lock_irq(&tty->ctrl_lock);
624 clear_bit(TTY_THROTTLED, &tty->flags);
625 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
626 put_pid(tty->session);
630 tty->ctrl_status = 0;
631 spin_unlock_irq(&tty->ctrl_lock);
634 * If one of the devices matches a console pointer, we
635 * cannot just call hangup() because that will cause
636 * tty->count and state->count to go out of sync.
637 * So we just call close() the right number of times.
641 for (n = 0; n < closecount; n++)
642 tty->ops->close(tty, cons_filp);
643 } else if (tty->ops->hangup)
644 tty->ops->hangup(tty);
646 * We don't want to have driver/ldisc interactions beyond the ones
647 * we did here. The driver layer expects no calls after ->hangup()
648 * from the ldisc side, which is now guaranteed.
650 set_bit(TTY_HUPPED, &tty->flags);
651 clear_bit(TTY_HUPPING, &tty->flags);
658 static void do_tty_hangup(struct work_struct *work)
660 struct tty_struct *tty =
661 container_of(work, struct tty_struct, hangup_work);
663 __tty_hangup(tty, 0);
667 * tty_hangup - trigger a hangup event
668 * @tty: tty to hangup
670 * A carrier loss (virtual or otherwise) has occurred on this like
671 * schedule a hangup sequence to run after this event.
674 void tty_hangup(struct tty_struct *tty)
676 tty_debug_hangup(tty, "hangup\n");
677 schedule_work(&tty->hangup_work);
680 EXPORT_SYMBOL(tty_hangup);
683 * tty_vhangup - process vhangup
684 * @tty: tty to hangup
686 * The user has asked via system call for the terminal to be hung up.
687 * We do this synchronously so that when the syscall returns the process
688 * is complete. That guarantee is necessary for security reasons.
691 void tty_vhangup(struct tty_struct *tty)
693 tty_debug_hangup(tty, "vhangup\n");
694 __tty_hangup(tty, 0);
697 EXPORT_SYMBOL(tty_vhangup);
701 * tty_vhangup_self - process vhangup for own ctty
703 * Perform a vhangup on the current controlling tty
706 void tty_vhangup_self(void)
708 struct tty_struct *tty;
710 tty = get_current_tty();
718 * tty_vhangup_session - hangup session leader exit
719 * @tty: tty to hangup
721 * The session leader is exiting and hanging up its controlling terminal.
722 * Every process in the foreground process group is signalled SIGHUP.
724 * We do this synchronously so that when the syscall returns the process
725 * is complete. That guarantee is necessary for security reasons.
728 void tty_vhangup_session(struct tty_struct *tty)
730 tty_debug_hangup(tty, "session hangup\n");
731 __tty_hangup(tty, 1);
735 * tty_hung_up_p - was tty hung up
736 * @filp: file pointer of tty
738 * Return true if the tty has been subject to a vhangup or a carrier
742 int tty_hung_up_p(struct file *filp)
744 return (filp && filp->f_op == &hung_up_tty_fops);
747 EXPORT_SYMBOL(tty_hung_up_p);
750 * stop_tty - propagate flow control
753 * Perform flow control to the driver. May be called
754 * on an already stopped device and will not re-call the driver
757 * This functionality is used by both the line disciplines for
758 * halting incoming flow and by the driver. It may therefore be
759 * called from any context, may be under the tty atomic_write_lock
766 void __stop_tty(struct tty_struct *tty)
775 void stop_tty(struct tty_struct *tty)
779 spin_lock_irqsave(&tty->flow_lock, flags);
781 spin_unlock_irqrestore(&tty->flow_lock, flags);
783 EXPORT_SYMBOL(stop_tty);
786 * start_tty - propagate flow control
789 * Start a tty that has been stopped if at all possible. If this
790 * tty was previous stopped and is now being started, the driver
791 * start method is invoked and the line discipline woken.
797 void __start_tty(struct tty_struct *tty)
799 if (!tty->stopped || tty->flow_stopped)
803 tty->ops->start(tty);
807 void start_tty(struct tty_struct *tty)
811 spin_lock_irqsave(&tty->flow_lock, flags);
813 spin_unlock_irqrestore(&tty->flow_lock, flags);
815 EXPORT_SYMBOL(start_tty);
817 static void tty_update_time(struct timespec *time)
819 unsigned long sec = get_seconds();
822 * We only care if the two values differ in anything other than the
823 * lower three bits (i.e every 8 seconds). If so, then we can update
824 * the time of the tty device, otherwise it could be construded as a
825 * security leak to let userspace know the exact timing of the tty.
827 if ((sec ^ time->tv_sec) & ~7)
832 * tty_read - read method for tty device files
833 * @file: pointer to tty file
835 * @count: size of user buffer
838 * Perform the read system call function on this terminal device. Checks
839 * for hung up devices before calling the line discipline method.
842 * Locks the line discipline internally while needed. Multiple
843 * read calls may be outstanding in parallel.
846 static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
850 struct inode *inode = file_inode(file);
851 struct tty_struct *tty = file_tty(file);
852 struct tty_ldisc *ld;
854 if (tty_paranoia_check(tty, inode, "tty_read"))
856 if (!tty || tty_io_error(tty))
859 /* We want to wait for the line discipline to sort out in this
861 ld = tty_ldisc_ref_wait(tty);
863 return hung_up_tty_read(file, buf, count, ppos);
865 i = ld->ops->read(tty, file, buf, count);
871 tty_update_time(&inode->i_atime);
876 static void tty_write_unlock(struct tty_struct *tty)
878 mutex_unlock(&tty->atomic_write_lock);
879 wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
882 static int tty_write_lock(struct tty_struct *tty, int ndelay)
884 if (!mutex_trylock(&tty->atomic_write_lock)) {
887 if (mutex_lock_interruptible(&tty->atomic_write_lock))
894 * Split writes up in sane blocksizes to avoid
895 * denial-of-service type attacks
897 static inline ssize_t do_tty_write(
898 ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
899 struct tty_struct *tty,
901 const char __user *buf,
904 ssize_t ret, written = 0;
907 ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
912 * We chunk up writes into a temporary buffer. This
913 * simplifies low-level drivers immensely, since they
914 * don't have locking issues and user mode accesses.
916 * But if TTY_NO_WRITE_SPLIT is set, we should use a
919 * The default chunk-size is 2kB, because the NTTY
920 * layer has problems with bigger chunks. It will
921 * claim to be able to handle more characters than
924 * FIXME: This can probably go away now except that 64K chunks
925 * are too likely to fail unless switched to vmalloc...
928 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
933 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
934 if (tty->write_cnt < chunk) {
935 unsigned char *buf_chunk;
940 buf_chunk = kmalloc(chunk, GFP_KERNEL);
945 kfree(tty->write_buf);
946 tty->write_cnt = chunk;
947 tty->write_buf = buf_chunk;
950 /* Do the write .. */
956 if (copy_from_user(tty->write_buf, buf, size))
958 ret = write(tty, file, tty->write_buf, size);
967 if (signal_pending(current))
972 tty_update_time(&file_inode(file)->i_mtime);
976 tty_write_unlock(tty);
981 * tty_write_message - write a message to a certain tty, not just the console.
982 * @tty: the destination tty_struct
983 * @msg: the message to write
985 * This is used for messages that need to be redirected to a specific tty.
986 * We don't put it into the syslog queue right now maybe in the future if
989 * We must still hold the BTM and test the CLOSING flag for the moment.
992 void tty_write_message(struct tty_struct *tty, char *msg)
995 mutex_lock(&tty->atomic_write_lock);
997 if (tty->ops->write && tty->count > 0)
998 tty->ops->write(tty, msg, strlen(msg));
1000 tty_write_unlock(tty);
1007 * tty_write - write method for tty device file
1008 * @file: tty file pointer
1009 * @buf: user data to write
1010 * @count: bytes to write
1013 * Write data to a tty device via the line discipline.
1016 * Locks the line discipline as required
1017 * Writes to the tty driver are serialized by the atomic_write_lock
1018 * and are then processed in chunks to the device. The line discipline
1019 * write method will not be invoked in parallel for each device.
1022 static ssize_t tty_write(struct file *file, const char __user *buf,
1023 size_t count, loff_t *ppos)
1025 struct tty_struct *tty = file_tty(file);
1026 struct tty_ldisc *ld;
1029 if (tty_paranoia_check(tty, file_inode(file), "tty_write"))
1031 if (!tty || !tty->ops->write || tty_io_error(tty))
1033 /* Short term debug to catch buggy drivers */
1034 if (tty->ops->write_room == NULL)
1035 tty_err(tty, "missing write_room method\n");
1036 ld = tty_ldisc_ref_wait(tty);
1038 return hung_up_tty_write(file, buf, count, ppos);
1039 if (!ld->ops->write)
1042 ret = do_tty_write(ld->ops->write, tty, file, buf, count);
1043 tty_ldisc_deref(ld);
1047 ssize_t redirected_tty_write(struct file *file, const char __user *buf,
1048 size_t count, loff_t *ppos)
1050 struct file *p = NULL;
1052 spin_lock(&redirect_lock);
1054 p = get_file(redirect);
1055 spin_unlock(&redirect_lock);
1059 res = vfs_write(p, buf, count, &p->f_pos);
1063 return tty_write(file, buf, count, ppos);
1067 * tty_send_xchar - send priority character
1069 * Send a high priority character to the tty even if stopped
1071 * Locking: none for xchar method, write ordering for write method.
1074 int tty_send_xchar(struct tty_struct *tty, char ch)
1076 int was_stopped = tty->stopped;
1078 if (tty->ops->send_xchar) {
1079 down_read(&tty->termios_rwsem);
1080 tty->ops->send_xchar(tty, ch);
1081 up_read(&tty->termios_rwsem);
1085 if (tty_write_lock(tty, 0) < 0)
1086 return -ERESTARTSYS;
1088 down_read(&tty->termios_rwsem);
1091 tty->ops->write(tty, &ch, 1);
1094 up_read(&tty->termios_rwsem);
1095 tty_write_unlock(tty);
1099 static char ptychar[] = "pqrstuvwxyzabcde";
1102 * pty_line_name - generate name for a pty
1103 * @driver: the tty driver in use
1104 * @index: the minor number
1105 * @p: output buffer of at least 6 bytes
1107 * Generate a name from a driver reference and write it to the output
1112 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1114 int i = index + driver->name_base;
1115 /* ->name is initialized to "ttyp", but "tty" is expected */
1116 sprintf(p, "%s%c%x",
1117 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1118 ptychar[i >> 4 & 0xf], i & 0xf);
1122 * tty_line_name - generate name for a tty
1123 * @driver: the tty driver in use
1124 * @index: the minor number
1125 * @p: output buffer of at least 7 bytes
1127 * Generate a name from a driver reference and write it to the output
1132 static ssize_t tty_line_name(struct tty_driver *driver, int index, char *p)
1134 if (driver->flags & TTY_DRIVER_UNNUMBERED_NODE)
1135 return sprintf(p, "%s", driver->name);
1137 return sprintf(p, "%s%d", driver->name,
1138 index + driver->name_base);
1142 * tty_driver_lookup_tty() - find an existing tty, if any
1143 * @driver: the driver for the tty
1144 * @idx: the minor number
1146 * Return the tty, if found. If not found, return NULL or ERR_PTR() if the
1147 * driver lookup() method returns an error.
1149 * Locking: tty_mutex must be held. If the tty is found, bump the tty kref.
1151 static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
1152 struct file *file, int idx)
1154 struct tty_struct *tty;
1156 if (driver->ops->lookup)
1158 tty = ERR_PTR(-EIO);
1160 tty = driver->ops->lookup(driver, file, idx);
1162 tty = driver->ttys[idx];
1170 * tty_init_termios - helper for termios setup
1171 * @tty: the tty to set up
1173 * Initialise the termios structures for this tty. Thus runs under
1174 * the tty_mutex currently so we can be relaxed about ordering.
1177 void tty_init_termios(struct tty_struct *tty)
1179 struct ktermios *tp;
1180 int idx = tty->index;
1182 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1183 tty->termios = tty->driver->init_termios;
1185 /* Check for lazy saved data */
1186 tp = tty->driver->termios[idx];
1189 tty->termios.c_line = tty->driver->init_termios.c_line;
1191 tty->termios = tty->driver->init_termios;
1193 /* Compatibility until drivers always set this */
1194 tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
1195 tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
1197 EXPORT_SYMBOL_GPL(tty_init_termios);
1199 int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty)
1201 tty_init_termios(tty);
1202 tty_driver_kref_get(driver);
1204 driver->ttys[tty->index] = tty;
1207 EXPORT_SYMBOL_GPL(tty_standard_install);
1210 * tty_driver_install_tty() - install a tty entry in the driver
1211 * @driver: the driver for the tty
1214 * Install a tty object into the driver tables. The tty->index field
1215 * will be set by the time this is called. This method is responsible
1216 * for ensuring any need additional structures are allocated and
1219 * Locking: tty_mutex for now
1221 static int tty_driver_install_tty(struct tty_driver *driver,
1222 struct tty_struct *tty)
1224 return driver->ops->install ? driver->ops->install(driver, tty) :
1225 tty_standard_install(driver, tty);
1229 * tty_driver_remove_tty() - remove a tty from the driver tables
1230 * @driver: the driver for the tty
1231 * @idx: the minor number
1233 * Remvoe a tty object from the driver tables. The tty->index field
1234 * will be set by the time this is called.
1236 * Locking: tty_mutex for now
1238 static void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *tty)
1240 if (driver->ops->remove)
1241 driver->ops->remove(driver, tty);
1243 driver->ttys[tty->index] = NULL;
1247 * tty_reopen() - fast re-open of an open tty
1248 * @tty - the tty to open
1250 * Return 0 on success, -errno on error.
1251 * Re-opens on master ptys are not allowed and return -EIO.
1253 * Locking: Caller must hold tty_lock
1255 static int tty_reopen(struct tty_struct *tty)
1257 struct tty_driver *driver = tty->driver;
1259 if (driver->type == TTY_DRIVER_TYPE_PTY &&
1260 driver->subtype == PTY_TYPE_MASTER)
1266 if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
1272 return tty_ldisc_reinit(tty, tty->termios.c_line);
1278 * tty_init_dev - initialise a tty device
1279 * @driver: tty driver we are opening a device on
1280 * @idx: device index
1281 * @ret_tty: returned tty structure
1283 * Prepare a tty device. This may not be a "new" clean device but
1284 * could also be an active device. The pty drivers require special
1285 * handling because of this.
1288 * The function is called under the tty_mutex, which
1289 * protects us from the tty struct or driver itself going away.
1291 * On exit the tty device has the line discipline attached and
1292 * a reference count of 1. If a pair was created for pty/tty use
1293 * and the other was a pty master then it too has a reference count of 1.
1295 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1296 * failed open. The new code protects the open with a mutex, so it's
1297 * really quite straightforward. The mutex locking can probably be
1298 * relaxed for the (most common) case of reopening a tty.
1301 struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
1303 struct tty_struct *tty;
1307 * First time open is complex, especially for PTY devices.
1308 * This code guarantees that either everything succeeds and the
1309 * TTY is ready for operation, or else the table slots are vacated
1310 * and the allocated memory released. (Except that the termios
1314 if (!try_module_get(driver->owner))
1315 return ERR_PTR(-ENODEV);
1317 tty = alloc_tty_struct(driver, idx);
1320 goto err_module_put;
1324 retval = tty_driver_install_tty(driver, tty);
1329 tty->port = driver->ports[idx];
1331 WARN_RATELIMIT(!tty->port,
1332 "%s: %s driver does not set tty->port. This will crash the kernel later. Fix the driver!\n",
1333 __func__, tty->driver->name);
1335 retval = tty_ldisc_lock(tty, 5 * HZ);
1337 goto err_release_lock;
1338 tty->port->itty = tty;
1341 * Structures all installed ... call the ldisc open routines.
1342 * If we fail here just call release_tty to clean up. No need
1343 * to decrement the use counts, as release_tty doesn't care.
1345 retval = tty_ldisc_setup(tty, tty->link);
1347 goto err_release_tty;
1348 tty_ldisc_unlock(tty);
1349 /* Return the tty locked so that it cannot vanish under the caller */
1354 free_tty_struct(tty);
1356 module_put(driver->owner);
1357 return ERR_PTR(retval);
1359 /* call the tty release_tty routine to clean out this slot */
1361 tty_ldisc_unlock(tty);
1362 tty_info_ratelimited(tty, "ldisc open failed (%d), clearing slot %d\n",
1366 release_tty(tty, idx);
1367 return ERR_PTR(retval);
1370 static void tty_free_termios(struct tty_struct *tty)
1372 struct ktermios *tp;
1373 int idx = tty->index;
1375 /* If the port is going to reset then it has no termios to save */
1376 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1379 /* Stash the termios data */
1380 tp = tty->driver->termios[idx];
1382 tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
1385 tty->driver->termios[idx] = tp;
1391 * tty_flush_works - flush all works of a tty/pty pair
1392 * @tty: tty device to flush works for (or either end of a pty pair)
1394 * Sync flush all works belonging to @tty (and the 'other' tty).
1396 static void tty_flush_works(struct tty_struct *tty)
1398 flush_work(&tty->SAK_work);
1399 flush_work(&tty->hangup_work);
1401 flush_work(&tty->link->SAK_work);
1402 flush_work(&tty->link->hangup_work);
1407 * release_one_tty - release tty structure memory
1408 * @kref: kref of tty we are obliterating
1410 * Releases memory associated with a tty structure, and clears out the
1411 * driver table slots. This function is called when a device is no longer
1412 * in use. It also gets called when setup of a device fails.
1415 * takes the file list lock internally when working on the list
1416 * of ttys that the driver keeps.
1418 * This method gets called from a work queue so that the driver private
1419 * cleanup ops can sleep (needed for USB at least)
1421 static void release_one_tty(struct work_struct *work)
1423 struct tty_struct *tty =
1424 container_of(work, struct tty_struct, hangup_work);
1425 struct tty_driver *driver = tty->driver;
1426 struct module *owner = driver->owner;
1428 if (tty->ops->cleanup)
1429 tty->ops->cleanup(tty);
1432 tty_driver_kref_put(driver);
1435 spin_lock(&tty->files_lock);
1436 list_del_init(&tty->tty_files);
1437 spin_unlock(&tty->files_lock);
1440 put_pid(tty->session);
1441 free_tty_struct(tty);
1444 static void queue_release_one_tty(struct kref *kref)
1446 struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1448 /* The hangup queue is now free so we can reuse it rather than
1449 waste a chunk of memory for each port */
1450 INIT_WORK(&tty->hangup_work, release_one_tty);
1451 schedule_work(&tty->hangup_work);
1455 * tty_kref_put - release a tty kref
1458 * Release a reference to a tty device and if need be let the kref
1459 * layer destruct the object for us
1462 void tty_kref_put(struct tty_struct *tty)
1465 kref_put(&tty->kref, queue_release_one_tty);
1467 EXPORT_SYMBOL(tty_kref_put);
1470 * release_tty - release tty structure memory
1472 * Release both @tty and a possible linked partner (think pty pair),
1473 * and decrement the refcount of the backing module.
1477 * takes the file list lock internally when working on the list
1478 * of ttys that the driver keeps.
1481 static void release_tty(struct tty_struct *tty, int idx)
1483 /* This should always be true but check for the moment */
1484 WARN_ON(tty->index != idx);
1485 WARN_ON(!mutex_is_locked(&tty_mutex));
1486 if (tty->ops->shutdown)
1487 tty->ops->shutdown(tty);
1488 tty_free_termios(tty);
1489 tty_driver_remove_tty(tty->driver, tty);
1490 tty->port->itty = NULL;
1492 tty->link->port->itty = NULL;
1493 tty_buffer_cancel_work(tty->port);
1495 tty_buffer_cancel_work(tty->link->port);
1497 tty_kref_put(tty->link);
1502 * tty_release_checks - check a tty before real release
1503 * @tty: tty to check
1504 * @o_tty: link of @tty (if any)
1505 * @idx: index of the tty
1507 * Performs some paranoid checking before true release of the @tty.
1508 * This is a no-op unless TTY_PARANOIA_CHECK is defined.
1510 static int tty_release_checks(struct tty_struct *tty, int idx)
1512 #ifdef TTY_PARANOIA_CHECK
1513 if (idx < 0 || idx >= tty->driver->num) {
1514 tty_debug(tty, "bad idx %d\n", idx);
1518 /* not much to check for devpts */
1519 if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)
1522 if (tty != tty->driver->ttys[idx]) {
1523 tty_debug(tty, "bad driver table[%d] = %p\n",
1524 idx, tty->driver->ttys[idx]);
1527 if (tty->driver->other) {
1528 struct tty_struct *o_tty = tty->link;
1530 if (o_tty != tty->driver->other->ttys[idx]) {
1531 tty_debug(tty, "bad other table[%d] = %p\n",
1532 idx, tty->driver->other->ttys[idx]);
1535 if (o_tty->link != tty) {
1536 tty_debug(tty, "bad link = %p\n", o_tty->link);
1545 * tty_kclose - closes tty opened by tty_kopen
1548 * Performs the final steps to release and free a tty device. It is the
1549 * same as tty_release_struct except that it also resets TTY_PORT_KOPENED
1550 * flag on tty->port.
1552 void tty_kclose(struct tty_struct *tty)
1555 * Ask the line discipline code to release its structures
1557 tty_ldisc_release(tty);
1559 /* Wait for pending work before tty destruction commmences */
1560 tty_flush_works(tty);
1562 tty_debug_hangup(tty, "freeing structure\n");
1564 * The release_tty function takes care of the details of clearing
1565 * the slots and preserving the termios structure. The tty_unlock_pair
1566 * should be safe as we keep a kref while the tty is locked (so the
1567 * unlock never unlocks a freed tty).
1569 mutex_lock(&tty_mutex);
1570 tty_port_set_kopened(tty->port, 0);
1571 release_tty(tty, tty->index);
1572 mutex_unlock(&tty_mutex);
1574 EXPORT_SYMBOL_GPL(tty_kclose);
1577 * tty_release_struct - release a tty struct
1579 * @idx: index of the tty
1581 * Performs the final steps to release and free a tty device. It is
1582 * roughly the reverse of tty_init_dev.
1584 void tty_release_struct(struct tty_struct *tty, int idx)
1587 * Ask the line discipline code to release its structures
1589 tty_ldisc_release(tty);
1591 /* Wait for pending work before tty destruction commmences */
1592 tty_flush_works(tty);
1594 tty_debug_hangup(tty, "freeing structure\n");
1596 * The release_tty function takes care of the details of clearing
1597 * the slots and preserving the termios structure. The tty_unlock_pair
1598 * should be safe as we keep a kref while the tty is locked (so the
1599 * unlock never unlocks a freed tty).
1601 mutex_lock(&tty_mutex);
1602 release_tty(tty, idx);
1603 mutex_unlock(&tty_mutex);
1605 EXPORT_SYMBOL_GPL(tty_release_struct);
1608 * tty_release - vfs callback for close
1609 * @inode: inode of tty
1610 * @filp: file pointer for handle to tty
1612 * Called the last time each file handle is closed that references
1613 * this tty. There may however be several such references.
1616 * Takes bkl. See tty_release_dev
1618 * Even releasing the tty structures is a tricky business.. We have
1619 * to be very careful that the structures are all released at the
1620 * same time, as interrupts might otherwise get the wrong pointers.
1622 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1623 * lead to double frees or releasing memory still in use.
1626 int tty_release(struct inode *inode, struct file *filp)
1628 struct tty_struct *tty = file_tty(filp);
1629 struct tty_struct *o_tty = NULL;
1630 int do_sleep, final;
1635 if (tty_paranoia_check(tty, inode, __func__))
1639 check_tty_count(tty, __func__);
1641 __tty_fasync(-1, filp, 0);
1644 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1645 tty->driver->subtype == PTY_TYPE_MASTER)
1648 if (tty_release_checks(tty, idx)) {
1653 tty_debug_hangup(tty, "releasing (count=%d)\n", tty->count);
1655 if (tty->ops->close)
1656 tty->ops->close(tty, filp);
1658 /* If tty is pty master, lock the slave pty (stable lock order) */
1659 tty_lock_slave(o_tty);
1662 * Sanity check: if tty->count is going to zero, there shouldn't be
1663 * any waiters on tty->read_wait or tty->write_wait. We test the
1664 * wait queues and kick everyone out _before_ actually starting to
1665 * close. This ensures that we won't block while releasing the tty
1668 * The test for the o_tty closing is necessary, since the master and
1669 * slave sides may close in any order. If the slave side closes out
1670 * first, its count will be one, since the master side holds an open.
1671 * Thus this test wouldn't be triggered at the time the slave closed,
1677 if (tty->count <= 1) {
1678 if (waitqueue_active(&tty->read_wait)) {
1679 wake_up_poll(&tty->read_wait, EPOLLIN);
1682 if (waitqueue_active(&tty->write_wait)) {
1683 wake_up_poll(&tty->write_wait, EPOLLOUT);
1687 if (o_tty && o_tty->count <= 1) {
1688 if (waitqueue_active(&o_tty->read_wait)) {
1689 wake_up_poll(&o_tty->read_wait, EPOLLIN);
1692 if (waitqueue_active(&o_tty->write_wait)) {
1693 wake_up_poll(&o_tty->write_wait, EPOLLOUT);
1702 tty_warn(tty, "read/write wait queue active!\n");
1704 schedule_timeout_killable(timeout);
1705 if (timeout < 120 * HZ)
1706 timeout = 2 * timeout + 1;
1708 timeout = MAX_SCHEDULE_TIMEOUT;
1712 if (--o_tty->count < 0) {
1713 tty_warn(tty, "bad slave count (%d)\n", o_tty->count);
1717 if (--tty->count < 0) {
1718 tty_warn(tty, "bad tty->count (%d)\n", tty->count);
1723 * We've decremented tty->count, so we need to remove this file
1724 * descriptor off the tty->tty_files list; this serves two
1726 * - check_tty_count sees the correct number of file descriptors
1727 * associated with this tty.
1728 * - do_tty_hangup no longer sees this file descriptor as
1729 * something that needs to be handled for hangups.
1734 * Perform some housekeeping before deciding whether to return.
1736 * If _either_ side is closing, make sure there aren't any
1737 * processes that still think tty or o_tty is their controlling
1741 read_lock(&tasklist_lock);
1742 session_clear_tty(tty->session);
1744 session_clear_tty(o_tty->session);
1745 read_unlock(&tasklist_lock);
1748 /* check whether both sides are closing ... */
1749 final = !tty->count && !(o_tty && o_tty->count);
1751 tty_unlock_slave(o_tty);
1754 /* At this point, the tty->count == 0 should ensure a dead tty
1755 cannot be re-opened by a racing opener */
1760 tty_debug_hangup(tty, "final close\n");
1762 tty_release_struct(tty, idx);
1767 * tty_open_current_tty - get locked tty of current task
1768 * @device: device number
1769 * @filp: file pointer to tty
1770 * @return: locked tty of the current task iff @device is /dev/tty
1772 * Performs a re-open of the current task's controlling tty.
1774 * We cannot return driver and index like for the other nodes because
1775 * devpts will not work then. It expects inodes to be from devpts FS.
1777 static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
1779 struct tty_struct *tty;
1782 if (device != MKDEV(TTYAUX_MAJOR, 0))
1785 tty = get_current_tty();
1787 return ERR_PTR(-ENXIO);
1789 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1792 tty_kref_put(tty); /* safe to drop the kref now */
1794 retval = tty_reopen(tty);
1797 tty = ERR_PTR(retval);
1803 * tty_lookup_driver - lookup a tty driver for a given device file
1804 * @device: device number
1805 * @filp: file pointer to tty
1806 * @index: index for the device in the @return driver
1807 * @return: driver for this inode (with increased refcount)
1809 * If @return is not erroneous, the caller is responsible to decrement the
1810 * refcount by tty_driver_kref_put.
1812 * Locking: tty_mutex protects get_tty_driver
1814 static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
1817 struct tty_driver *driver;
1821 case MKDEV(TTY_MAJOR, 0): {
1822 extern struct tty_driver *console_driver;
1823 driver = tty_driver_kref_get(console_driver);
1824 *index = fg_console;
1828 case MKDEV(TTYAUX_MAJOR, 1): {
1829 struct tty_driver *console_driver = console_device(index);
1830 if (console_driver) {
1831 driver = tty_driver_kref_get(console_driver);
1832 if (driver && filp) {
1833 /* Don't let /dev/console block */
1834 filp->f_flags |= O_NONBLOCK;
1838 return ERR_PTR(-ENODEV);
1841 driver = get_tty_driver(device, index);
1843 return ERR_PTR(-ENODEV);
1850 * tty_kopen - open a tty device for kernel
1851 * @device: dev_t of device to open
1853 * Opens tty exclusively for kernel. Performs the driver lookup,
1854 * makes sure it's not already opened and performs the first-time
1855 * tty initialization.
1857 * Returns the locked initialized &tty_struct
1859 * Claims the global tty_mutex to serialize:
1860 * - concurrent first-time tty initialization
1861 * - concurrent tty driver removal w/ lookup
1862 * - concurrent tty removal from driver table
1864 struct tty_struct *tty_kopen(dev_t device)
1866 struct tty_struct *tty;
1867 struct tty_driver *driver = NULL;
1870 mutex_lock(&tty_mutex);
1871 driver = tty_lookup_driver(device, NULL, &index);
1872 if (IS_ERR(driver)) {
1873 mutex_unlock(&tty_mutex);
1874 return ERR_CAST(driver);
1877 /* check whether we're reopening an existing tty */
1878 tty = tty_driver_lookup_tty(driver, NULL, index);
1883 /* drop kref from tty_driver_lookup_tty() */
1885 tty = ERR_PTR(-EBUSY);
1886 } else { /* tty_init_dev returns tty with the tty_lock held */
1887 tty = tty_init_dev(driver, index);
1890 tty_port_set_kopened(tty->port, 1);
1893 mutex_unlock(&tty_mutex);
1894 tty_driver_kref_put(driver);
1897 EXPORT_SYMBOL_GPL(tty_kopen);
1900 * tty_open_by_driver - open a tty device
1901 * @device: dev_t of device to open
1902 * @inode: inode of device file
1903 * @filp: file pointer to tty
1905 * Performs the driver lookup, checks for a reopen, or otherwise
1906 * performs the first-time tty initialization.
1908 * Returns the locked initialized or re-opened &tty_struct
1910 * Claims the global tty_mutex to serialize:
1911 * - concurrent first-time tty initialization
1912 * - concurrent tty driver removal w/ lookup
1913 * - concurrent tty removal from driver table
1915 static struct tty_struct *tty_open_by_driver(dev_t device, struct inode *inode,
1918 struct tty_struct *tty;
1919 struct tty_driver *driver = NULL;
1923 mutex_lock(&tty_mutex);
1924 driver = tty_lookup_driver(device, filp, &index);
1925 if (IS_ERR(driver)) {
1926 mutex_unlock(&tty_mutex);
1927 return ERR_CAST(driver);
1930 /* check whether we're reopening an existing tty */
1931 tty = tty_driver_lookup_tty(driver, filp, index);
1933 mutex_unlock(&tty_mutex);
1938 if (tty_port_kopened(tty->port)) {
1940 mutex_unlock(&tty_mutex);
1941 tty = ERR_PTR(-EBUSY);
1944 mutex_unlock(&tty_mutex);
1945 retval = tty_lock_interruptible(tty);
1946 tty_kref_put(tty); /* drop kref from tty_driver_lookup_tty() */
1948 if (retval == -EINTR)
1949 retval = -ERESTARTSYS;
1950 tty = ERR_PTR(retval);
1953 retval = tty_reopen(tty);
1956 tty = ERR_PTR(retval);
1958 } else { /* Returns with the tty_lock held for now */
1959 tty = tty_init_dev(driver, index);
1960 mutex_unlock(&tty_mutex);
1963 tty_driver_kref_put(driver);
1968 * tty_open - open a tty device
1969 * @inode: inode of device file
1970 * @filp: file pointer to tty
1972 * tty_open and tty_release keep up the tty count that contains the
1973 * number of opens done on a tty. We cannot use the inode-count, as
1974 * different inodes might point to the same tty.
1976 * Open-counting is needed for pty masters, as well as for keeping
1977 * track of serial lines: DTR is dropped when the last close happens.
1978 * (This is not done solely through tty->count, now. - Ted 1/27/92)
1980 * The termios state of a pty is reset on first open so that
1981 * settings don't persist across reuse.
1983 * Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.
1984 * tty->count should protect the rest.
1985 * ->siglock protects ->signal/->sighand
1987 * Note: the tty_unlock/lock cases without a ref are only safe due to
1991 static int tty_open(struct inode *inode, struct file *filp)
1993 struct tty_struct *tty;
1995 dev_t device = inode->i_rdev;
1996 unsigned saved_flags = filp->f_flags;
1998 nonseekable_open(inode, filp);
2001 retval = tty_alloc_file(filp);
2005 tty = tty_open_current_tty(device, filp);
2007 tty = tty_open_by_driver(device, inode, filp);
2010 tty_free_file(filp);
2011 retval = PTR_ERR(tty);
2012 if (retval != -EAGAIN || signal_pending(current))
2018 tty_add_file(tty, filp);
2020 check_tty_count(tty, __func__);
2021 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
2024 retval = tty->ops->open(tty, filp);
2027 filp->f_flags = saved_flags;
2030 tty_debug_hangup(tty, "open error %d, releasing\n", retval);
2032 tty_unlock(tty); /* need to call tty_release without BTM */
2033 tty_release(inode, filp);
2034 if (retval != -ERESTARTSYS)
2037 if (signal_pending(current))
2042 * Need to reset f_op in case a hangup happened.
2044 if (tty_hung_up_p(filp))
2045 filp->f_op = &tty_fops;
2048 clear_bit(TTY_HUPPED, &tty->flags);
2050 noctty = (filp->f_flags & O_NOCTTY) ||
2051 (IS_ENABLED(CONFIG_VT) && device == MKDEV(TTY_MAJOR, 0)) ||
2052 device == MKDEV(TTYAUX_MAJOR, 1) ||
2053 (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2054 tty->driver->subtype == PTY_TYPE_MASTER);
2056 tty_open_proc_set_tty(filp, tty);
2064 * tty_poll - check tty status
2065 * @filp: file being polled
2066 * @wait: poll wait structures to update
2068 * Call the line discipline polling method to obtain the poll
2069 * status of the device.
2071 * Locking: locks called line discipline but ldisc poll method
2072 * may be re-entered freely by other callers.
2075 static __poll_t tty_poll(struct file *filp, poll_table *wait)
2077 struct tty_struct *tty = file_tty(filp);
2078 struct tty_ldisc *ld;
2081 if (tty_paranoia_check(tty, file_inode(filp), "tty_poll"))
2084 ld = tty_ldisc_ref_wait(tty);
2086 return hung_up_tty_poll(filp, wait);
2088 ret = ld->ops->poll(tty, filp, wait);
2089 tty_ldisc_deref(ld);
2093 static int __tty_fasync(int fd, struct file *filp, int on)
2095 struct tty_struct *tty = file_tty(filp);
2096 unsigned long flags;
2099 if (tty_paranoia_check(tty, file_inode(filp), "tty_fasync"))
2102 retval = fasync_helper(fd, filp, on, &tty->fasync);
2110 spin_lock_irqsave(&tty->ctrl_lock, flags);
2113 type = PIDTYPE_PGID;
2115 pid = task_pid(current);
2119 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2120 __f_setown(filp, pid, type, 0);
2128 static int tty_fasync(int fd, struct file *filp, int on)
2130 struct tty_struct *tty = file_tty(filp);
2131 int retval = -ENOTTY;
2134 if (!tty_hung_up_p(filp))
2135 retval = __tty_fasync(fd, filp, on);
2142 * tiocsti - fake input character
2143 * @tty: tty to fake input into
2144 * @p: pointer to character
2146 * Fake input to a tty device. Does the necessary locking and
2149 * FIXME: does not honour flow control ??
2152 * Called functions take tty_ldiscs_lock
2153 * current->signal->tty check is safe without locks
2155 * FIXME: may race normal receive processing
2158 static int tiocsti(struct tty_struct *tty, char __user *p)
2161 struct tty_ldisc *ld;
2163 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2165 if (get_user(ch, p))
2167 tty_audit_tiocsti(tty, ch);
2168 ld = tty_ldisc_ref_wait(tty);
2171 ld->ops->receive_buf(tty, &ch, &mbz, 1);
2172 tty_ldisc_deref(ld);
2177 * tiocgwinsz - implement window query ioctl
2179 * @arg: user buffer for result
2181 * Copies the kernel idea of the window size into the user buffer.
2183 * Locking: tty->winsize_mutex is taken to ensure the winsize data
2187 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2191 mutex_lock(&tty->winsize_mutex);
2192 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2193 mutex_unlock(&tty->winsize_mutex);
2195 return err ? -EFAULT: 0;
2199 * tty_do_resize - resize event
2200 * @tty: tty being resized
2201 * @rows: rows (character)
2202 * @cols: cols (character)
2204 * Update the termios variables and send the necessary signals to
2205 * peform a terminal resize correctly
2208 int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
2213 mutex_lock(&tty->winsize_mutex);
2214 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
2217 /* Signal the foreground process group */
2218 pgrp = tty_get_pgrp(tty);
2220 kill_pgrp(pgrp, SIGWINCH, 1);
2225 mutex_unlock(&tty->winsize_mutex);
2228 EXPORT_SYMBOL(tty_do_resize);
2231 * tiocswinsz - implement window size set ioctl
2232 * @tty; tty side of tty
2233 * @arg: user buffer for result
2235 * Copies the user idea of the window size to the kernel. Traditionally
2236 * this is just advisory information but for the Linux console it
2237 * actually has driver level meaning and triggers a VC resize.
2240 * Driver dependent. The default do_resize method takes the
2241 * tty termios mutex and ctrl_lock. The console takes its own lock
2242 * then calls into the default method.
2245 static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
2247 struct winsize tmp_ws;
2248 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2251 if (tty->ops->resize)
2252 return tty->ops->resize(tty, &tmp_ws);
2254 return tty_do_resize(tty, &tmp_ws);
2258 * tioccons - allow admin to move logical console
2259 * @file: the file to become console
2261 * Allow the administrator to move the redirected console device
2263 * Locking: uses redirect_lock to guard the redirect information
2266 static int tioccons(struct file *file)
2268 if (!capable(CAP_SYS_ADMIN))
2270 if (file->f_op->write == redirected_tty_write) {
2272 spin_lock(&redirect_lock);
2275 spin_unlock(&redirect_lock);
2280 spin_lock(&redirect_lock);
2282 spin_unlock(&redirect_lock);
2285 redirect = get_file(file);
2286 spin_unlock(&redirect_lock);
2291 * fionbio - non blocking ioctl
2292 * @file: file to set blocking value
2293 * @p: user parameter
2295 * Historical tty interfaces had a blocking control ioctl before
2296 * the generic functionality existed. This piece of history is preserved
2297 * in the expected tty API of posix OS's.
2299 * Locking: none, the open file handle ensures it won't go away.
2302 static int fionbio(struct file *file, int __user *p)
2306 if (get_user(nonblock, p))
2309 spin_lock(&file->f_lock);
2311 file->f_flags |= O_NONBLOCK;
2313 file->f_flags &= ~O_NONBLOCK;
2314 spin_unlock(&file->f_lock);
2319 * tiocsetd - set line discipline
2321 * @p: pointer to user data
2323 * Set the line discipline according to user request.
2325 * Locking: see tty_set_ldisc, this function is just a helper
2328 static int tiocsetd(struct tty_struct *tty, int __user *p)
2333 if (get_user(disc, p))
2336 ret = tty_set_ldisc(tty, disc);
2342 * tiocgetd - get line discipline
2344 * @p: pointer to user data
2346 * Retrieves the line discipline id directly from the ldisc.
2348 * Locking: waits for ldisc reference (in case the line discipline
2349 * is changing or the tty is being hungup)
2352 static int tiocgetd(struct tty_struct *tty, int __user *p)
2354 struct tty_ldisc *ld;
2357 ld = tty_ldisc_ref_wait(tty);
2360 ret = put_user(ld->ops->num, p);
2361 tty_ldisc_deref(ld);
2366 * send_break - performed time break
2367 * @tty: device to break on
2368 * @duration: timeout in mS
2370 * Perform a timed break on hardware that lacks its own driver level
2371 * timed break functionality.
2374 * atomic_write_lock serializes
2378 static int send_break(struct tty_struct *tty, unsigned int duration)
2382 if (tty->ops->break_ctl == NULL)
2385 if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2386 retval = tty->ops->break_ctl(tty, duration);
2388 /* Do the work ourselves */
2389 if (tty_write_lock(tty, 0) < 0)
2391 retval = tty->ops->break_ctl(tty, -1);
2394 if (!signal_pending(current))
2395 msleep_interruptible(duration);
2396 retval = tty->ops->break_ctl(tty, 0);
2398 tty_write_unlock(tty);
2399 if (signal_pending(current))
2406 * tty_tiocmget - get modem status
2408 * @file: user file pointer
2409 * @p: pointer to result
2411 * Obtain the modem status bits from the tty driver if the feature
2412 * is supported. Return -EINVAL if it is not available.
2414 * Locking: none (up to the driver)
2417 static int tty_tiocmget(struct tty_struct *tty, int __user *p)
2419 int retval = -EINVAL;
2421 if (tty->ops->tiocmget) {
2422 retval = tty->ops->tiocmget(tty);
2425 retval = put_user(retval, p);
2431 * tty_tiocmset - set modem status
2433 * @cmd: command - clear bits, set bits or set all
2434 * @p: pointer to desired bits
2436 * Set the modem status bits from the tty driver if the feature
2437 * is supported. Return -EINVAL if it is not available.
2439 * Locking: none (up to the driver)
2442 static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
2446 unsigned int set, clear, val;
2448 if (tty->ops->tiocmset == NULL)
2451 retval = get_user(val, p);
2467 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2468 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2469 return tty->ops->tiocmset(tty, set, clear);
2472 static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
2474 int retval = -EINVAL;
2475 struct serial_icounter_struct icount;
2476 memset(&icount, 0, sizeof(icount));
2477 if (tty->ops->get_icount)
2478 retval = tty->ops->get_icount(tty, &icount);
2481 if (copy_to_user(arg, &icount, sizeof(icount)))
2486 static void tty_warn_deprecated_flags(struct serial_struct __user *ss)
2488 static DEFINE_RATELIMIT_STATE(depr_flags,
2489 DEFAULT_RATELIMIT_INTERVAL,
2490 DEFAULT_RATELIMIT_BURST);
2491 char comm[TASK_COMM_LEN];
2494 if (get_user(flags, &ss->flags))
2497 flags &= ASYNC_DEPRECATED;
2499 if (flags && __ratelimit(&depr_flags))
2500 pr_warn("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
2501 __func__, get_task_comm(comm, current), flags);
2505 * if pty, return the slave side (real_tty)
2506 * otherwise, return self
2508 static struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
2510 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2511 tty->driver->subtype == PTY_TYPE_MASTER)
2517 * Split this up, as gcc can choke on it otherwise..
2519 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2521 struct tty_struct *tty = file_tty(file);
2522 struct tty_struct *real_tty;
2523 void __user *p = (void __user *)arg;
2525 struct tty_ldisc *ld;
2527 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2530 real_tty = tty_pair_get_tty(tty);
2533 * Factor out some common prep work
2541 retval = tty_check_change(tty);
2544 if (cmd != TIOCCBRK) {
2545 tty_wait_until_sent(tty, 0);
2546 if (signal_pending(current))
2557 return tiocsti(tty, p);
2559 return tiocgwinsz(real_tty, p);
2561 return tiocswinsz(real_tty, p);
2563 return real_tty != tty ? -EINVAL : tioccons(file);
2565 return fionbio(file, p);
2567 set_bit(TTY_EXCLUSIVE, &tty->flags);
2570 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2574 int excl = test_bit(TTY_EXCLUSIVE, &tty->flags);
2575 return put_user(excl, (int __user *)p);
2578 return tiocgetd(tty, p);
2580 return tiocsetd(tty, p);
2582 if (!capable(CAP_SYS_ADMIN))
2588 unsigned int ret = new_encode_dev(tty_devnum(real_tty));
2589 return put_user(ret, (unsigned int __user *)p);
2594 case TIOCSBRK: /* Turn break on, unconditionally */
2595 if (tty->ops->break_ctl)
2596 return tty->ops->break_ctl(tty, -1);
2598 case TIOCCBRK: /* Turn break off, unconditionally */
2599 if (tty->ops->break_ctl)
2600 return tty->ops->break_ctl(tty, 0);
2602 case TCSBRK: /* SVID version: non-zero arg --> no break */
2603 /* non-zero arg means wait for all output data
2604 * to be sent (performed above) but don't send break.
2605 * This is used by the tcdrain() termios function.
2608 return send_break(tty, 250);
2610 case TCSBRKP: /* support for POSIX tcsendbreak() */
2611 return send_break(tty, arg ? arg*100 : 250);
2614 return tty_tiocmget(tty, p);
2618 return tty_tiocmset(tty, cmd, p);
2620 retval = tty_tiocgicount(tty, p);
2621 /* For the moment allow fall through to the old method */
2622 if (retval != -EINVAL)
2629 /* flush tty buffer and allow ldisc to process ioctl */
2630 tty_buffer_flush(tty, NULL);
2635 tty_warn_deprecated_flags(p);
2638 /* Special because the struct file is needed */
2639 return ptm_open_peer(file, tty, (int)arg);
2641 retval = tty_jobctrl_ioctl(tty, real_tty, file, cmd, arg);
2642 if (retval != -ENOIOCTLCMD)
2645 if (tty->ops->ioctl) {
2646 retval = tty->ops->ioctl(tty, cmd, arg);
2647 if (retval != -ENOIOCTLCMD)
2650 ld = tty_ldisc_ref_wait(tty);
2652 return hung_up_tty_ioctl(file, cmd, arg);
2654 if (ld->ops->ioctl) {
2655 retval = ld->ops->ioctl(tty, file, cmd, arg);
2656 if (retval == -ENOIOCTLCMD)
2659 tty_ldisc_deref(ld);
2663 #ifdef CONFIG_COMPAT
2664 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2667 struct tty_struct *tty = file_tty(file);
2668 struct tty_ldisc *ld;
2669 int retval = -ENOIOCTLCMD;
2671 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2674 if (tty->ops->compat_ioctl) {
2675 retval = tty->ops->compat_ioctl(tty, cmd, arg);
2676 if (retval != -ENOIOCTLCMD)
2680 ld = tty_ldisc_ref_wait(tty);
2682 return hung_up_tty_compat_ioctl(file, cmd, arg);
2683 if (ld->ops->compat_ioctl)
2684 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
2686 retval = n_tty_compat_ioctl_helper(tty, file, cmd, arg);
2687 tty_ldisc_deref(ld);
2693 static int this_tty(const void *t, struct file *file, unsigned fd)
2695 if (likely(file->f_op->read != tty_read))
2697 return file_tty(file) != t ? 0 : fd + 1;
2701 * This implements the "Secure Attention Key" --- the idea is to
2702 * prevent trojan horses by killing all processes associated with this
2703 * tty when the user hits the "Secure Attention Key". Required for
2704 * super-paranoid applications --- see the Orange Book for more details.
2706 * This code could be nicer; ideally it should send a HUP, wait a few
2707 * seconds, then send a INT, and then a KILL signal. But you then
2708 * have to coordinate with the init process, since all processes associated
2709 * with the current tty must be dead before the new getty is allowed
2712 * Now, if it would be correct ;-/ The current code has a nasty hole -
2713 * it doesn't catch files in flight. We may send the descriptor to ourselves
2714 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
2716 * Nasty bug: do_SAK is being called in interrupt context. This can
2717 * deadlock. We punt it up to process context. AKPM - 16Mar2001
2719 void __do_SAK(struct tty_struct *tty)
2724 struct task_struct *g, *p;
2725 struct pid *session;
2730 session = tty->session;
2732 tty_ldisc_flush(tty);
2734 tty_driver_flush_buffer(tty);
2736 read_lock(&tasklist_lock);
2737 /* Kill the entire session */
2738 do_each_pid_task(session, PIDTYPE_SID, p) {
2739 tty_notice(tty, "SAK: killed process %d (%s): by session\n",
2740 task_pid_nr(p), p->comm);
2741 send_sig(SIGKILL, p, 1);
2742 } while_each_pid_task(session, PIDTYPE_SID, p);
2744 /* Now kill any processes that happen to have the tty open */
2745 do_each_thread(g, p) {
2746 if (p->signal->tty == tty) {
2747 tty_notice(tty, "SAK: killed process %d (%s): by controlling tty\n",
2748 task_pid_nr(p), p->comm);
2749 send_sig(SIGKILL, p, 1);
2753 i = iterate_fd(p->files, 0, this_tty, tty);
2755 tty_notice(tty, "SAK: killed process %d (%s): by fd#%d\n",
2756 task_pid_nr(p), p->comm, i - 1);
2757 force_sig(SIGKILL, p);
2760 } while_each_thread(g, p);
2761 read_unlock(&tasklist_lock);
2765 static void do_SAK_work(struct work_struct *work)
2767 struct tty_struct *tty =
2768 container_of(work, struct tty_struct, SAK_work);
2773 * The tq handling here is a little racy - tty->SAK_work may already be queued.
2774 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
2775 * the values which we write to it will be identical to the values which it
2776 * already has. --akpm
2778 void do_SAK(struct tty_struct *tty)
2782 schedule_work(&tty->SAK_work);
2785 EXPORT_SYMBOL(do_SAK);
2787 static int dev_match_devt(struct device *dev, const void *data)
2789 const dev_t *devt = data;
2790 return dev->devt == *devt;
2793 /* Must put_device() after it's unused! */
2794 static struct device *tty_get_device(struct tty_struct *tty)
2796 dev_t devt = tty_devnum(tty);
2797 return class_find_device(tty_class, NULL, &devt, dev_match_devt);
2804 * This subroutine allocates and initializes a tty structure.
2806 * Locking: none - tty in question is not exposed at this point
2809 struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
2811 struct tty_struct *tty;
2813 tty = kzalloc(sizeof(*tty), GFP_KERNEL);
2817 kref_init(&tty->kref);
2818 tty->magic = TTY_MAGIC;
2819 if (tty_ldisc_init(tty)) {
2823 tty->session = NULL;
2825 mutex_init(&tty->legacy_mutex);
2826 mutex_init(&tty->throttle_mutex);
2827 init_rwsem(&tty->termios_rwsem);
2828 mutex_init(&tty->winsize_mutex);
2829 init_ldsem(&tty->ldisc_sem);
2830 init_waitqueue_head(&tty->write_wait);
2831 init_waitqueue_head(&tty->read_wait);
2832 INIT_WORK(&tty->hangup_work, do_tty_hangup);
2833 mutex_init(&tty->atomic_write_lock);
2834 spin_lock_init(&tty->ctrl_lock);
2835 spin_lock_init(&tty->flow_lock);
2836 spin_lock_init(&tty->files_lock);
2837 INIT_LIST_HEAD(&tty->tty_files);
2838 INIT_WORK(&tty->SAK_work, do_SAK_work);
2840 tty->driver = driver;
2841 tty->ops = driver->ops;
2843 tty_line_name(driver, idx, tty->name);
2844 tty->dev = tty_get_device(tty);
2850 * tty_put_char - write one character to a tty
2854 * Write one byte to the tty using the provided put_char method
2855 * if present. Returns the number of characters successfully output.
2857 * Note: the specific put_char operation in the driver layer may go
2858 * away soon. Don't call it directly, use this method
2861 int tty_put_char(struct tty_struct *tty, unsigned char ch)
2863 if (tty->ops->put_char)
2864 return tty->ops->put_char(tty, ch);
2865 return tty->ops->write(tty, &ch, 1);
2867 EXPORT_SYMBOL_GPL(tty_put_char);
2869 struct class *tty_class;
2871 static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
2872 unsigned int index, unsigned int count)
2876 /* init here, since reused cdevs cause crashes */
2877 driver->cdevs[index] = cdev_alloc();
2878 if (!driver->cdevs[index])
2880 driver->cdevs[index]->ops = &tty_fops;
2881 driver->cdevs[index]->owner = driver->owner;
2882 err = cdev_add(driver->cdevs[index], dev, count);
2884 kobject_put(&driver->cdevs[index]->kobj);
2889 * tty_register_device - register a tty device
2890 * @driver: the tty driver that describes the tty device
2891 * @index: the index in the tty driver for this tty device
2892 * @device: a struct device that is associated with this tty device.
2893 * This field is optional, if there is no known struct device
2894 * for this tty device it can be set to NULL safely.
2896 * Returns a pointer to the struct device for this tty device
2897 * (or ERR_PTR(-EFOO) on error).
2899 * This call is required to be made to register an individual tty device
2900 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
2901 * that bit is not set, this function should not be called by a tty
2907 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
2908 struct device *device)
2910 return tty_register_device_attr(driver, index, device, NULL, NULL);
2912 EXPORT_SYMBOL(tty_register_device);
2914 static void tty_device_create_release(struct device *dev)
2916 dev_dbg(dev, "releasing...\n");
2921 * tty_register_device_attr - register a tty device
2922 * @driver: the tty driver that describes the tty device
2923 * @index: the index in the tty driver for this tty device
2924 * @device: a struct device that is associated with this tty device.
2925 * This field is optional, if there is no known struct device
2926 * for this tty device it can be set to NULL safely.
2927 * @drvdata: Driver data to be set to device.
2928 * @attr_grp: Attribute group to be set on device.
2930 * Returns a pointer to the struct device for this tty device
2931 * (or ERR_PTR(-EFOO) on error).
2933 * This call is required to be made to register an individual tty device
2934 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
2935 * that bit is not set, this function should not be called by a tty
2940 struct device *tty_register_device_attr(struct tty_driver *driver,
2941 unsigned index, struct device *device,
2943 const struct attribute_group **attr_grp)
2946 dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
2947 struct ktermios *tp;
2951 if (index >= driver->num) {
2952 pr_err("%s: Attempt to register invalid tty line number (%d)\n",
2953 driver->name, index);
2954 return ERR_PTR(-EINVAL);
2957 if (driver->type == TTY_DRIVER_TYPE_PTY)
2958 pty_line_name(driver, index, name);
2960 tty_line_name(driver, index, name);
2962 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
2964 return ERR_PTR(-ENOMEM);
2967 dev->class = tty_class;
2968 dev->parent = device;
2969 dev->release = tty_device_create_release;
2970 dev_set_name(dev, "%s", name);
2971 dev->groups = attr_grp;
2972 dev_set_drvdata(dev, drvdata);
2974 dev_set_uevent_suppress(dev, 1);
2976 retval = device_register(dev);
2980 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
2982 * Free any saved termios data so that the termios state is
2983 * reset when reusing a minor number.
2985 tp = driver->termios[index];
2987 driver->termios[index] = NULL;
2991 retval = tty_cdev_add(driver, devt, index, 1);
2996 dev_set_uevent_suppress(dev, 0);
2997 kobject_uevent(&dev->kobj, KOBJ_ADD);
3006 return ERR_PTR(retval);
3008 EXPORT_SYMBOL_GPL(tty_register_device_attr);
3011 * tty_unregister_device - unregister a tty device
3012 * @driver: the tty driver that describes the tty device
3013 * @index: the index in the tty driver for this tty device
3015 * If a tty device is registered with a call to tty_register_device() then
3016 * this function must be called when the tty device is gone.
3021 void tty_unregister_device(struct tty_driver *driver, unsigned index)
3023 device_destroy(tty_class,
3024 MKDEV(driver->major, driver->minor_start) + index);
3025 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3026 cdev_del(driver->cdevs[index]);
3027 driver->cdevs[index] = NULL;
3030 EXPORT_SYMBOL(tty_unregister_device);
3033 * __tty_alloc_driver -- allocate tty driver
3034 * @lines: count of lines this driver can handle at most
3035 * @owner: module which is responsible for this driver
3036 * @flags: some of TTY_DRIVER_* flags, will be set in driver->flags
3038 * This should not be called directly, some of the provided macros should be
3039 * used instead. Use IS_ERR and friends on @retval.
3041 struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
3042 unsigned long flags)
3044 struct tty_driver *driver;
3045 unsigned int cdevs = 1;
3048 if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
3049 return ERR_PTR(-EINVAL);
3051 driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
3053 return ERR_PTR(-ENOMEM);
3055 kref_init(&driver->kref);
3056 driver->magic = TTY_DRIVER_MAGIC;
3057 driver->num = lines;
3058 driver->owner = owner;
3059 driver->flags = flags;
3061 if (!(flags & TTY_DRIVER_DEVPTS_MEM)) {
3062 driver->ttys = kcalloc(lines, sizeof(*driver->ttys),
3064 driver->termios = kcalloc(lines, sizeof(*driver->termios),
3066 if (!driver->ttys || !driver->termios) {
3072 if (!(flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3073 driver->ports = kcalloc(lines, sizeof(*driver->ports),
3075 if (!driver->ports) {
3082 driver->cdevs = kcalloc(cdevs, sizeof(*driver->cdevs), GFP_KERNEL);
3083 if (!driver->cdevs) {
3090 kfree(driver->ports);
3091 kfree(driver->ttys);
3092 kfree(driver->termios);
3093 kfree(driver->cdevs);
3095 return ERR_PTR(err);
3097 EXPORT_SYMBOL(__tty_alloc_driver);
3099 static void destruct_tty_driver(struct kref *kref)
3101 struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
3103 struct ktermios *tp;
3105 if (driver->flags & TTY_DRIVER_INSTALLED) {
3106 for (i = 0; i < driver->num; i++) {
3107 tp = driver->termios[i];
3109 driver->termios[i] = NULL;
3112 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3113 tty_unregister_device(driver, i);
3115 proc_tty_unregister_driver(driver);
3116 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
3117 cdev_del(driver->cdevs[0]);
3119 kfree(driver->cdevs);
3120 kfree(driver->ports);
3121 kfree(driver->termios);
3122 kfree(driver->ttys);
3126 void tty_driver_kref_put(struct tty_driver *driver)
3128 kref_put(&driver->kref, destruct_tty_driver);
3130 EXPORT_SYMBOL(tty_driver_kref_put);
3132 void tty_set_operations(struct tty_driver *driver,
3133 const struct tty_operations *op)
3137 EXPORT_SYMBOL(tty_set_operations);
3139 void put_tty_driver(struct tty_driver *d)
3141 tty_driver_kref_put(d);
3143 EXPORT_SYMBOL(put_tty_driver);
3146 * Called by a tty driver to register itself.
3148 int tty_register_driver(struct tty_driver *driver)
3155 if (!driver->major) {
3156 error = alloc_chrdev_region(&dev, driver->minor_start,
3157 driver->num, driver->name);
3159 driver->major = MAJOR(dev);
3160 driver->minor_start = MINOR(dev);
3163 dev = MKDEV(driver->major, driver->minor_start);
3164 error = register_chrdev_region(dev, driver->num, driver->name);
3169 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) {
3170 error = tty_cdev_add(driver, dev, 0, driver->num);
3172 goto err_unreg_char;
3175 mutex_lock(&tty_mutex);
3176 list_add(&driver->tty_drivers, &tty_drivers);
3177 mutex_unlock(&tty_mutex);
3179 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
3180 for (i = 0; i < driver->num; i++) {
3181 d = tty_register_device(driver, i, NULL);
3184 goto err_unreg_devs;
3188 proc_tty_register_driver(driver);
3189 driver->flags |= TTY_DRIVER_INSTALLED;
3193 for (i--; i >= 0; i--)
3194 tty_unregister_device(driver, i);
3196 mutex_lock(&tty_mutex);
3197 list_del(&driver->tty_drivers);
3198 mutex_unlock(&tty_mutex);
3201 unregister_chrdev_region(dev, driver->num);
3205 EXPORT_SYMBOL(tty_register_driver);
3208 * Called by a tty driver to unregister itself.
3210 int tty_unregister_driver(struct tty_driver *driver)
3214 if (driver->refcount)
3217 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3219 mutex_lock(&tty_mutex);
3220 list_del(&driver->tty_drivers);
3221 mutex_unlock(&tty_mutex);
3225 EXPORT_SYMBOL(tty_unregister_driver);
3227 dev_t tty_devnum(struct tty_struct *tty)
3229 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3231 EXPORT_SYMBOL(tty_devnum);
3233 void tty_default_fops(struct file_operations *fops)
3238 static char *tty_devnode(struct device *dev, umode_t *mode)
3242 if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
3243 dev->devt == MKDEV(TTYAUX_MAJOR, 2))
3248 static int __init tty_class_init(void)
3250 tty_class = class_create(THIS_MODULE, "tty");
3251 if (IS_ERR(tty_class))
3252 return PTR_ERR(tty_class);
3253 tty_class->devnode = tty_devnode;
3257 postcore_initcall(tty_class_init);
3259 /* 3/2004 jmc: why do these devices exist? */
3260 static struct cdev tty_cdev, console_cdev;
3262 static ssize_t show_cons_active(struct device *dev,
3263 struct device_attribute *attr, char *buf)
3265 struct console *cs[16];
3271 for_each_console(c) {
3276 if ((c->flags & CON_ENABLED) == 0)
3279 if (i >= ARRAY_SIZE(cs))
3283 int index = cs[i]->index;
3284 struct tty_driver *drv = cs[i]->device(cs[i], &index);
3286 /* don't resolve tty0 as some programs depend on it */
3287 if (drv && (cs[i]->index > 0 || drv->major != TTY_MAJOR))
3288 count += tty_line_name(drv, index, buf + count);
3290 count += sprintf(buf + count, "%s%d",
3291 cs[i]->name, cs[i]->index);
3293 count += sprintf(buf + count, "%c", i ? ' ':'\n');
3299 static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
3301 static struct attribute *cons_dev_attrs[] = {
3302 &dev_attr_active.attr,
3306 ATTRIBUTE_GROUPS(cons_dev);
3308 static struct device *consdev;
3310 void console_sysfs_notify(void)
3313 sysfs_notify(&consdev->kobj, NULL, "active");
3317 * Ok, now we can initialize the rest of the tty devices and can count
3318 * on memory allocations, interrupts etc..
3320 int __init tty_init(void)
3322 cdev_init(&tty_cdev, &tty_fops);
3323 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3324 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3325 panic("Couldn't register /dev/tty driver\n");
3326 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
3328 cdev_init(&console_cdev, &console_fops);
3329 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3330 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3331 panic("Couldn't register /dev/console driver\n");
3332 consdev = device_create_with_groups(tty_class, NULL,
3333 MKDEV(TTYAUX_MAJOR, 1), NULL,
3334 cons_dev_groups, "console");
3335 if (IS_ERR(consdev))
3339 vty_init(&console_fops);