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 timespec64 *time)
819 time64_t sec = ktime_get_real_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;
1260 if (driver->type == TTY_DRIVER_TYPE_PTY &&
1261 driver->subtype == PTY_TYPE_MASTER)
1267 if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
1275 retval = tty_ldisc_reinit(tty, tty->termios.c_line);
1283 * tty_init_dev - initialise a tty device
1284 * @driver: tty driver we are opening a device on
1285 * @idx: device index
1286 * @ret_tty: returned tty structure
1288 * Prepare a tty device. This may not be a "new" clean device but
1289 * could also be an active device. The pty drivers require special
1290 * handling because of this.
1293 * The function is called under the tty_mutex, which
1294 * protects us from the tty struct or driver itself going away.
1296 * On exit the tty device has the line discipline attached and
1297 * a reference count of 1. If a pair was created for pty/tty use
1298 * and the other was a pty master then it too has a reference count of 1.
1300 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1301 * failed open. The new code protects the open with a mutex, so it's
1302 * really quite straightforward. The mutex locking can probably be
1303 * relaxed for the (most common) case of reopening a tty.
1306 struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
1308 struct tty_struct *tty;
1312 * First time open is complex, especially for PTY devices.
1313 * This code guarantees that either everything succeeds and the
1314 * TTY is ready for operation, or else the table slots are vacated
1315 * and the allocated memory released. (Except that the termios
1319 if (!try_module_get(driver->owner))
1320 return ERR_PTR(-ENODEV);
1322 tty = alloc_tty_struct(driver, idx);
1325 goto err_module_put;
1329 retval = tty_driver_install_tty(driver, tty);
1334 tty->port = driver->ports[idx];
1336 WARN_RATELIMIT(!tty->port,
1337 "%s: %s driver does not set tty->port. This will crash the kernel later. Fix the driver!\n",
1338 __func__, tty->driver->name);
1340 retval = tty_ldisc_lock(tty, 5 * HZ);
1342 goto err_release_lock;
1343 tty->port->itty = tty;
1346 * Structures all installed ... call the ldisc open routines.
1347 * If we fail here just call release_tty to clean up. No need
1348 * to decrement the use counts, as release_tty doesn't care.
1350 retval = tty_ldisc_setup(tty, tty->link);
1352 goto err_release_tty;
1353 tty_ldisc_unlock(tty);
1354 /* Return the tty locked so that it cannot vanish under the caller */
1359 free_tty_struct(tty);
1361 module_put(driver->owner);
1362 return ERR_PTR(retval);
1364 /* call the tty release_tty routine to clean out this slot */
1366 tty_ldisc_unlock(tty);
1367 tty_info_ratelimited(tty, "ldisc open failed (%d), clearing slot %d\n",
1371 release_tty(tty, idx);
1372 return ERR_PTR(retval);
1375 static void tty_free_termios(struct tty_struct *tty)
1377 struct ktermios *tp;
1378 int idx = tty->index;
1380 /* If the port is going to reset then it has no termios to save */
1381 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1384 /* Stash the termios data */
1385 tp = tty->driver->termios[idx];
1387 tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
1390 tty->driver->termios[idx] = tp;
1396 * tty_flush_works - flush all works of a tty/pty pair
1397 * @tty: tty device to flush works for (or either end of a pty pair)
1399 * Sync flush all works belonging to @tty (and the 'other' tty).
1401 static void tty_flush_works(struct tty_struct *tty)
1403 flush_work(&tty->SAK_work);
1404 flush_work(&tty->hangup_work);
1406 flush_work(&tty->link->SAK_work);
1407 flush_work(&tty->link->hangup_work);
1412 * release_one_tty - release tty structure memory
1413 * @kref: kref of tty we are obliterating
1415 * Releases memory associated with a tty structure, and clears out the
1416 * driver table slots. This function is called when a device is no longer
1417 * in use. It also gets called when setup of a device fails.
1420 * takes the file list lock internally when working on the list
1421 * of ttys that the driver keeps.
1423 * This method gets called from a work queue so that the driver private
1424 * cleanup ops can sleep (needed for USB at least)
1426 static void release_one_tty(struct work_struct *work)
1428 struct tty_struct *tty =
1429 container_of(work, struct tty_struct, hangup_work);
1430 struct tty_driver *driver = tty->driver;
1431 struct module *owner = driver->owner;
1433 if (tty->ops->cleanup)
1434 tty->ops->cleanup(tty);
1437 tty_driver_kref_put(driver);
1440 spin_lock(&tty->files_lock);
1441 list_del_init(&tty->tty_files);
1442 spin_unlock(&tty->files_lock);
1445 put_pid(tty->session);
1446 free_tty_struct(tty);
1449 static void queue_release_one_tty(struct kref *kref)
1451 struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1453 /* The hangup queue is now free so we can reuse it rather than
1454 waste a chunk of memory for each port */
1455 INIT_WORK(&tty->hangup_work, release_one_tty);
1456 schedule_work(&tty->hangup_work);
1460 * tty_kref_put - release a tty kref
1463 * Release a reference to a tty device and if need be let the kref
1464 * layer destruct the object for us
1467 void tty_kref_put(struct tty_struct *tty)
1470 kref_put(&tty->kref, queue_release_one_tty);
1472 EXPORT_SYMBOL(tty_kref_put);
1475 * release_tty - release tty structure memory
1477 * Release both @tty and a possible linked partner (think pty pair),
1478 * and decrement the refcount of the backing module.
1482 * takes the file list lock internally when working on the list
1483 * of ttys that the driver keeps.
1486 static void release_tty(struct tty_struct *tty, int idx)
1488 /* This should always be true but check for the moment */
1489 WARN_ON(tty->index != idx);
1490 WARN_ON(!mutex_is_locked(&tty_mutex));
1491 if (tty->ops->shutdown)
1492 tty->ops->shutdown(tty);
1493 tty_free_termios(tty);
1494 tty_driver_remove_tty(tty->driver, tty);
1495 tty->port->itty = NULL;
1497 tty->link->port->itty = NULL;
1498 tty_buffer_cancel_work(tty->port);
1500 tty_buffer_cancel_work(tty->link->port);
1502 tty_kref_put(tty->link);
1507 * tty_release_checks - check a tty before real release
1508 * @tty: tty to check
1509 * @o_tty: link of @tty (if any)
1510 * @idx: index of the tty
1512 * Performs some paranoid checking before true release of the @tty.
1513 * This is a no-op unless TTY_PARANOIA_CHECK is defined.
1515 static int tty_release_checks(struct tty_struct *tty, int idx)
1517 #ifdef TTY_PARANOIA_CHECK
1518 if (idx < 0 || idx >= tty->driver->num) {
1519 tty_debug(tty, "bad idx %d\n", idx);
1523 /* not much to check for devpts */
1524 if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)
1527 if (tty != tty->driver->ttys[idx]) {
1528 tty_debug(tty, "bad driver table[%d] = %p\n",
1529 idx, tty->driver->ttys[idx]);
1532 if (tty->driver->other) {
1533 struct tty_struct *o_tty = tty->link;
1535 if (o_tty != tty->driver->other->ttys[idx]) {
1536 tty_debug(tty, "bad other table[%d] = %p\n",
1537 idx, tty->driver->other->ttys[idx]);
1540 if (o_tty->link != tty) {
1541 tty_debug(tty, "bad link = %p\n", o_tty->link);
1550 * tty_kclose - closes tty opened by tty_kopen
1553 * Performs the final steps to release and free a tty device. It is the
1554 * same as tty_release_struct except that it also resets TTY_PORT_KOPENED
1555 * flag on tty->port.
1557 void tty_kclose(struct tty_struct *tty)
1560 * Ask the line discipline code to release its structures
1562 tty_ldisc_release(tty);
1564 /* Wait for pending work before tty destruction commmences */
1565 tty_flush_works(tty);
1567 tty_debug_hangup(tty, "freeing structure\n");
1569 * The release_tty function takes care of the details of clearing
1570 * the slots and preserving the termios structure. The tty_unlock_pair
1571 * should be safe as we keep a kref while the tty is locked (so the
1572 * unlock never unlocks a freed tty).
1574 mutex_lock(&tty_mutex);
1575 tty_port_set_kopened(tty->port, 0);
1576 release_tty(tty, tty->index);
1577 mutex_unlock(&tty_mutex);
1579 EXPORT_SYMBOL_GPL(tty_kclose);
1582 * tty_release_struct - release a tty struct
1584 * @idx: index of the tty
1586 * Performs the final steps to release and free a tty device. It is
1587 * roughly the reverse of tty_init_dev.
1589 void tty_release_struct(struct tty_struct *tty, int idx)
1592 * Ask the line discipline code to release its structures
1594 tty_ldisc_release(tty);
1596 /* Wait for pending work before tty destruction commmences */
1597 tty_flush_works(tty);
1599 tty_debug_hangup(tty, "freeing structure\n");
1601 * The release_tty function takes care of the details of clearing
1602 * the slots and preserving the termios structure. The tty_unlock_pair
1603 * should be safe as we keep a kref while the tty is locked (so the
1604 * unlock never unlocks a freed tty).
1606 mutex_lock(&tty_mutex);
1607 release_tty(tty, idx);
1608 mutex_unlock(&tty_mutex);
1610 EXPORT_SYMBOL_GPL(tty_release_struct);
1613 * tty_release - vfs callback for close
1614 * @inode: inode of tty
1615 * @filp: file pointer for handle to tty
1617 * Called the last time each file handle is closed that references
1618 * this tty. There may however be several such references.
1621 * Takes bkl. See tty_release_dev
1623 * Even releasing the tty structures is a tricky business.. We have
1624 * to be very careful that the structures are all released at the
1625 * same time, as interrupts might otherwise get the wrong pointers.
1627 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1628 * lead to double frees or releasing memory still in use.
1631 int tty_release(struct inode *inode, struct file *filp)
1633 struct tty_struct *tty = file_tty(filp);
1634 struct tty_struct *o_tty = NULL;
1635 int do_sleep, final;
1640 if (tty_paranoia_check(tty, inode, __func__))
1644 check_tty_count(tty, __func__);
1646 __tty_fasync(-1, filp, 0);
1649 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1650 tty->driver->subtype == PTY_TYPE_MASTER)
1653 if (tty_release_checks(tty, idx)) {
1658 tty_debug_hangup(tty, "releasing (count=%d)\n", tty->count);
1660 if (tty->ops->close)
1661 tty->ops->close(tty, filp);
1663 /* If tty is pty master, lock the slave pty (stable lock order) */
1664 tty_lock_slave(o_tty);
1667 * Sanity check: if tty->count is going to zero, there shouldn't be
1668 * any waiters on tty->read_wait or tty->write_wait. We test the
1669 * wait queues and kick everyone out _before_ actually starting to
1670 * close. This ensures that we won't block while releasing the tty
1673 * The test for the o_tty closing is necessary, since the master and
1674 * slave sides may close in any order. If the slave side closes out
1675 * first, its count will be one, since the master side holds an open.
1676 * Thus this test wouldn't be triggered at the time the slave closed,
1682 if (tty->count <= 1) {
1683 if (waitqueue_active(&tty->read_wait)) {
1684 wake_up_poll(&tty->read_wait, EPOLLIN);
1687 if (waitqueue_active(&tty->write_wait)) {
1688 wake_up_poll(&tty->write_wait, EPOLLOUT);
1692 if (o_tty && o_tty->count <= 1) {
1693 if (waitqueue_active(&o_tty->read_wait)) {
1694 wake_up_poll(&o_tty->read_wait, EPOLLIN);
1697 if (waitqueue_active(&o_tty->write_wait)) {
1698 wake_up_poll(&o_tty->write_wait, EPOLLOUT);
1707 tty_warn(tty, "read/write wait queue active!\n");
1709 schedule_timeout_killable(timeout);
1710 if (timeout < 120 * HZ)
1711 timeout = 2 * timeout + 1;
1713 timeout = MAX_SCHEDULE_TIMEOUT;
1717 if (--o_tty->count < 0) {
1718 tty_warn(tty, "bad slave count (%d)\n", o_tty->count);
1722 if (--tty->count < 0) {
1723 tty_warn(tty, "bad tty->count (%d)\n", tty->count);
1728 * We've decremented tty->count, so we need to remove this file
1729 * descriptor off the tty->tty_files list; this serves two
1731 * - check_tty_count sees the correct number of file descriptors
1732 * associated with this tty.
1733 * - do_tty_hangup no longer sees this file descriptor as
1734 * something that needs to be handled for hangups.
1739 * Perform some housekeeping before deciding whether to return.
1741 * If _either_ side is closing, make sure there aren't any
1742 * processes that still think tty or o_tty is their controlling
1746 read_lock(&tasklist_lock);
1747 session_clear_tty(tty->session);
1749 session_clear_tty(o_tty->session);
1750 read_unlock(&tasklist_lock);
1753 /* check whether both sides are closing ... */
1754 final = !tty->count && !(o_tty && o_tty->count);
1756 tty_unlock_slave(o_tty);
1759 /* At this point, the tty->count == 0 should ensure a dead tty
1760 cannot be re-opened by a racing opener */
1765 tty_debug_hangup(tty, "final close\n");
1767 tty_release_struct(tty, idx);
1772 * tty_open_current_tty - get locked tty of current task
1773 * @device: device number
1774 * @filp: file pointer to tty
1775 * @return: locked tty of the current task iff @device is /dev/tty
1777 * Performs a re-open of the current task's controlling tty.
1779 * We cannot return driver and index like for the other nodes because
1780 * devpts will not work then. It expects inodes to be from devpts FS.
1782 static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
1784 struct tty_struct *tty;
1787 if (device != MKDEV(TTYAUX_MAJOR, 0))
1790 tty = get_current_tty();
1792 return ERR_PTR(-ENXIO);
1794 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1797 tty_kref_put(tty); /* safe to drop the kref now */
1799 retval = tty_reopen(tty);
1802 tty = ERR_PTR(retval);
1808 * tty_lookup_driver - lookup a tty driver for a given device file
1809 * @device: device number
1810 * @filp: file pointer to tty
1811 * @index: index for the device in the @return driver
1812 * @return: driver for this inode (with increased refcount)
1814 * If @return is not erroneous, the caller is responsible to decrement the
1815 * refcount by tty_driver_kref_put.
1817 * Locking: tty_mutex protects get_tty_driver
1819 static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
1822 struct tty_driver *driver;
1826 case MKDEV(TTY_MAJOR, 0): {
1827 extern struct tty_driver *console_driver;
1828 driver = tty_driver_kref_get(console_driver);
1829 *index = fg_console;
1833 case MKDEV(TTYAUX_MAJOR, 1): {
1834 struct tty_driver *console_driver = console_device(index);
1835 if (console_driver) {
1836 driver = tty_driver_kref_get(console_driver);
1837 if (driver && filp) {
1838 /* Don't let /dev/console block */
1839 filp->f_flags |= O_NONBLOCK;
1843 return ERR_PTR(-ENODEV);
1846 driver = get_tty_driver(device, index);
1848 return ERR_PTR(-ENODEV);
1855 * tty_kopen - open a tty device for kernel
1856 * @device: dev_t of device to open
1858 * Opens tty exclusively for kernel. Performs the driver lookup,
1859 * makes sure it's not already opened and performs the first-time
1860 * tty initialization.
1862 * Returns the locked initialized &tty_struct
1864 * Claims the global tty_mutex to serialize:
1865 * - concurrent first-time tty initialization
1866 * - concurrent tty driver removal w/ lookup
1867 * - concurrent tty removal from driver table
1869 struct tty_struct *tty_kopen(dev_t device)
1871 struct tty_struct *tty;
1872 struct tty_driver *driver = NULL;
1875 mutex_lock(&tty_mutex);
1876 driver = tty_lookup_driver(device, NULL, &index);
1877 if (IS_ERR(driver)) {
1878 mutex_unlock(&tty_mutex);
1879 return ERR_CAST(driver);
1882 /* check whether we're reopening an existing tty */
1883 tty = tty_driver_lookup_tty(driver, NULL, index);
1888 /* drop kref from tty_driver_lookup_tty() */
1890 tty = ERR_PTR(-EBUSY);
1891 } else { /* tty_init_dev returns tty with the tty_lock held */
1892 tty = tty_init_dev(driver, index);
1895 tty_port_set_kopened(tty->port, 1);
1898 mutex_unlock(&tty_mutex);
1899 tty_driver_kref_put(driver);
1902 EXPORT_SYMBOL_GPL(tty_kopen);
1905 * tty_open_by_driver - open a tty device
1906 * @device: dev_t of device to open
1907 * @inode: inode of device file
1908 * @filp: file pointer to tty
1910 * Performs the driver lookup, checks for a reopen, or otherwise
1911 * performs the first-time tty initialization.
1913 * Returns the locked initialized or re-opened &tty_struct
1915 * Claims the global tty_mutex to serialize:
1916 * - concurrent first-time tty initialization
1917 * - concurrent tty driver removal w/ lookup
1918 * - concurrent tty removal from driver table
1920 static struct tty_struct *tty_open_by_driver(dev_t device, struct inode *inode,
1923 struct tty_struct *tty;
1924 struct tty_driver *driver = NULL;
1928 mutex_lock(&tty_mutex);
1929 driver = tty_lookup_driver(device, filp, &index);
1930 if (IS_ERR(driver)) {
1931 mutex_unlock(&tty_mutex);
1932 return ERR_CAST(driver);
1935 /* check whether we're reopening an existing tty */
1936 tty = tty_driver_lookup_tty(driver, filp, index);
1938 mutex_unlock(&tty_mutex);
1943 if (tty_port_kopened(tty->port)) {
1945 mutex_unlock(&tty_mutex);
1946 tty = ERR_PTR(-EBUSY);
1949 mutex_unlock(&tty_mutex);
1950 retval = tty_lock_interruptible(tty);
1951 tty_kref_put(tty); /* drop kref from tty_driver_lookup_tty() */
1953 if (retval == -EINTR)
1954 retval = -ERESTARTSYS;
1955 tty = ERR_PTR(retval);
1958 retval = tty_reopen(tty);
1961 tty = ERR_PTR(retval);
1963 } else { /* Returns with the tty_lock held for now */
1964 tty = tty_init_dev(driver, index);
1965 mutex_unlock(&tty_mutex);
1968 tty_driver_kref_put(driver);
1973 * tty_open - open a tty device
1974 * @inode: inode of device file
1975 * @filp: file pointer to tty
1977 * tty_open and tty_release keep up the tty count that contains the
1978 * number of opens done on a tty. We cannot use the inode-count, as
1979 * different inodes might point to the same tty.
1981 * Open-counting is needed for pty masters, as well as for keeping
1982 * track of serial lines: DTR is dropped when the last close happens.
1983 * (This is not done solely through tty->count, now. - Ted 1/27/92)
1985 * The termios state of a pty is reset on first open so that
1986 * settings don't persist across reuse.
1988 * Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.
1989 * tty->count should protect the rest.
1990 * ->siglock protects ->signal/->sighand
1992 * Note: the tty_unlock/lock cases without a ref are only safe due to
1996 static int tty_open(struct inode *inode, struct file *filp)
1998 struct tty_struct *tty;
2000 dev_t device = inode->i_rdev;
2001 unsigned saved_flags = filp->f_flags;
2003 nonseekable_open(inode, filp);
2006 retval = tty_alloc_file(filp);
2010 tty = tty_open_current_tty(device, filp);
2012 tty = tty_open_by_driver(device, inode, filp);
2015 tty_free_file(filp);
2016 retval = PTR_ERR(tty);
2017 if (retval != -EAGAIN || signal_pending(current))
2023 tty_add_file(tty, filp);
2025 check_tty_count(tty, __func__);
2026 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
2029 retval = tty->ops->open(tty, filp);
2032 filp->f_flags = saved_flags;
2035 tty_debug_hangup(tty, "open error %d, releasing\n", retval);
2037 tty_unlock(tty); /* need to call tty_release without BTM */
2038 tty_release(inode, filp);
2039 if (retval != -ERESTARTSYS)
2042 if (signal_pending(current))
2047 * Need to reset f_op in case a hangup happened.
2049 if (tty_hung_up_p(filp))
2050 filp->f_op = &tty_fops;
2053 clear_bit(TTY_HUPPED, &tty->flags);
2055 noctty = (filp->f_flags & O_NOCTTY) ||
2056 (IS_ENABLED(CONFIG_VT) && device == MKDEV(TTY_MAJOR, 0)) ||
2057 device == MKDEV(TTYAUX_MAJOR, 1) ||
2058 (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2059 tty->driver->subtype == PTY_TYPE_MASTER);
2061 tty_open_proc_set_tty(filp, tty);
2069 * tty_poll - check tty status
2070 * @filp: file being polled
2071 * @wait: poll wait structures to update
2073 * Call the line discipline polling method to obtain the poll
2074 * status of the device.
2076 * Locking: locks called line discipline but ldisc poll method
2077 * may be re-entered freely by other callers.
2080 static __poll_t tty_poll(struct file *filp, poll_table *wait)
2082 struct tty_struct *tty = file_tty(filp);
2083 struct tty_ldisc *ld;
2086 if (tty_paranoia_check(tty, file_inode(filp), "tty_poll"))
2089 ld = tty_ldisc_ref_wait(tty);
2091 return hung_up_tty_poll(filp, wait);
2093 ret = ld->ops->poll(tty, filp, wait);
2094 tty_ldisc_deref(ld);
2098 static int __tty_fasync(int fd, struct file *filp, int on)
2100 struct tty_struct *tty = file_tty(filp);
2101 unsigned long flags;
2104 if (tty_paranoia_check(tty, file_inode(filp), "tty_fasync"))
2107 retval = fasync_helper(fd, filp, on, &tty->fasync);
2115 spin_lock_irqsave(&tty->ctrl_lock, flags);
2118 type = PIDTYPE_PGID;
2120 pid = task_pid(current);
2121 type = PIDTYPE_TGID;
2124 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2125 __f_setown(filp, pid, type, 0);
2133 static int tty_fasync(int fd, struct file *filp, int on)
2135 struct tty_struct *tty = file_tty(filp);
2136 int retval = -ENOTTY;
2139 if (!tty_hung_up_p(filp))
2140 retval = __tty_fasync(fd, filp, on);
2147 * tiocsti - fake input character
2148 * @tty: tty to fake input into
2149 * @p: pointer to character
2151 * Fake input to a tty device. Does the necessary locking and
2154 * FIXME: does not honour flow control ??
2157 * Called functions take tty_ldiscs_lock
2158 * current->signal->tty check is safe without locks
2160 * FIXME: may race normal receive processing
2163 static int tiocsti(struct tty_struct *tty, char __user *p)
2166 struct tty_ldisc *ld;
2168 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2170 if (get_user(ch, p))
2172 tty_audit_tiocsti(tty, ch);
2173 ld = tty_ldisc_ref_wait(tty);
2176 ld->ops->receive_buf(tty, &ch, &mbz, 1);
2177 tty_ldisc_deref(ld);
2182 * tiocgwinsz - implement window query ioctl
2184 * @arg: user buffer for result
2186 * Copies the kernel idea of the window size into the user buffer.
2188 * Locking: tty->winsize_mutex is taken to ensure the winsize data
2192 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2196 mutex_lock(&tty->winsize_mutex);
2197 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2198 mutex_unlock(&tty->winsize_mutex);
2200 return err ? -EFAULT: 0;
2204 * tty_do_resize - resize event
2205 * @tty: tty being resized
2206 * @rows: rows (character)
2207 * @cols: cols (character)
2209 * Update the termios variables and send the necessary signals to
2210 * peform a terminal resize correctly
2213 int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
2218 mutex_lock(&tty->winsize_mutex);
2219 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
2222 /* Signal the foreground process group */
2223 pgrp = tty_get_pgrp(tty);
2225 kill_pgrp(pgrp, SIGWINCH, 1);
2230 mutex_unlock(&tty->winsize_mutex);
2233 EXPORT_SYMBOL(tty_do_resize);
2236 * tiocswinsz - implement window size set ioctl
2237 * @tty; tty side of tty
2238 * @arg: user buffer for result
2240 * Copies the user idea of the window size to the kernel. Traditionally
2241 * this is just advisory information but for the Linux console it
2242 * actually has driver level meaning and triggers a VC resize.
2245 * Driver dependent. The default do_resize method takes the
2246 * tty termios mutex and ctrl_lock. The console takes its own lock
2247 * then calls into the default method.
2250 static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
2252 struct winsize tmp_ws;
2253 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2256 if (tty->ops->resize)
2257 return tty->ops->resize(tty, &tmp_ws);
2259 return tty_do_resize(tty, &tmp_ws);
2263 * tioccons - allow admin to move logical console
2264 * @file: the file to become console
2266 * Allow the administrator to move the redirected console device
2268 * Locking: uses redirect_lock to guard the redirect information
2271 static int tioccons(struct file *file)
2273 if (!capable(CAP_SYS_ADMIN))
2275 if (file->f_op->write == redirected_tty_write) {
2277 spin_lock(&redirect_lock);
2280 spin_unlock(&redirect_lock);
2285 spin_lock(&redirect_lock);
2287 spin_unlock(&redirect_lock);
2290 redirect = get_file(file);
2291 spin_unlock(&redirect_lock);
2296 * fionbio - non blocking ioctl
2297 * @file: file to set blocking value
2298 * @p: user parameter
2300 * Historical tty interfaces had a blocking control ioctl before
2301 * the generic functionality existed. This piece of history is preserved
2302 * in the expected tty API of posix OS's.
2304 * Locking: none, the open file handle ensures it won't go away.
2307 static int fionbio(struct file *file, int __user *p)
2311 if (get_user(nonblock, p))
2314 spin_lock(&file->f_lock);
2316 file->f_flags |= O_NONBLOCK;
2318 file->f_flags &= ~O_NONBLOCK;
2319 spin_unlock(&file->f_lock);
2324 * tiocsetd - set line discipline
2326 * @p: pointer to user data
2328 * Set the line discipline according to user request.
2330 * Locking: see tty_set_ldisc, this function is just a helper
2333 static int tiocsetd(struct tty_struct *tty, int __user *p)
2338 if (get_user(disc, p))
2341 ret = tty_set_ldisc(tty, disc);
2347 * tiocgetd - get line discipline
2349 * @p: pointer to user data
2351 * Retrieves the line discipline id directly from the ldisc.
2353 * Locking: waits for ldisc reference (in case the line discipline
2354 * is changing or the tty is being hungup)
2357 static int tiocgetd(struct tty_struct *tty, int __user *p)
2359 struct tty_ldisc *ld;
2362 ld = tty_ldisc_ref_wait(tty);
2365 ret = put_user(ld->ops->num, p);
2366 tty_ldisc_deref(ld);
2371 * send_break - performed time break
2372 * @tty: device to break on
2373 * @duration: timeout in mS
2375 * Perform a timed break on hardware that lacks its own driver level
2376 * timed break functionality.
2379 * atomic_write_lock serializes
2383 static int send_break(struct tty_struct *tty, unsigned int duration)
2387 if (tty->ops->break_ctl == NULL)
2390 if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2391 retval = tty->ops->break_ctl(tty, duration);
2393 /* Do the work ourselves */
2394 if (tty_write_lock(tty, 0) < 0)
2396 retval = tty->ops->break_ctl(tty, -1);
2399 if (!signal_pending(current))
2400 msleep_interruptible(duration);
2401 retval = tty->ops->break_ctl(tty, 0);
2403 tty_write_unlock(tty);
2404 if (signal_pending(current))
2411 * tty_tiocmget - get modem status
2413 * @file: user file pointer
2414 * @p: pointer to result
2416 * Obtain the modem status bits from the tty driver if the feature
2417 * is supported. Return -EINVAL if it is not available.
2419 * Locking: none (up to the driver)
2422 static int tty_tiocmget(struct tty_struct *tty, int __user *p)
2424 int retval = -EINVAL;
2426 if (tty->ops->tiocmget) {
2427 retval = tty->ops->tiocmget(tty);
2430 retval = put_user(retval, p);
2436 * tty_tiocmset - set modem status
2438 * @cmd: command - clear bits, set bits or set all
2439 * @p: pointer to desired bits
2441 * Set the modem status bits from the tty driver if the feature
2442 * is supported. Return -EINVAL if it is not available.
2444 * Locking: none (up to the driver)
2447 static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
2451 unsigned int set, clear, val;
2453 if (tty->ops->tiocmset == NULL)
2456 retval = get_user(val, p);
2472 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2473 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2474 return tty->ops->tiocmset(tty, set, clear);
2477 static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
2479 int retval = -EINVAL;
2480 struct serial_icounter_struct icount;
2481 memset(&icount, 0, sizeof(icount));
2482 if (tty->ops->get_icount)
2483 retval = tty->ops->get_icount(tty, &icount);
2486 if (copy_to_user(arg, &icount, sizeof(icount)))
2491 static void tty_warn_deprecated_flags(struct serial_struct __user *ss)
2493 static DEFINE_RATELIMIT_STATE(depr_flags,
2494 DEFAULT_RATELIMIT_INTERVAL,
2495 DEFAULT_RATELIMIT_BURST);
2496 char comm[TASK_COMM_LEN];
2499 if (get_user(flags, &ss->flags))
2502 flags &= ASYNC_DEPRECATED;
2504 if (flags && __ratelimit(&depr_flags))
2505 pr_warn("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
2506 __func__, get_task_comm(comm, current), flags);
2510 * if pty, return the slave side (real_tty)
2511 * otherwise, return self
2513 static struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
2515 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2516 tty->driver->subtype == PTY_TYPE_MASTER)
2522 * Split this up, as gcc can choke on it otherwise..
2524 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2526 struct tty_struct *tty = file_tty(file);
2527 struct tty_struct *real_tty;
2528 void __user *p = (void __user *)arg;
2530 struct tty_ldisc *ld;
2532 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2535 real_tty = tty_pair_get_tty(tty);
2538 * Factor out some common prep work
2546 retval = tty_check_change(tty);
2549 if (cmd != TIOCCBRK) {
2550 tty_wait_until_sent(tty, 0);
2551 if (signal_pending(current))
2562 return tiocsti(tty, p);
2564 return tiocgwinsz(real_tty, p);
2566 return tiocswinsz(real_tty, p);
2568 return real_tty != tty ? -EINVAL : tioccons(file);
2570 return fionbio(file, p);
2572 set_bit(TTY_EXCLUSIVE, &tty->flags);
2575 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2579 int excl = test_bit(TTY_EXCLUSIVE, &tty->flags);
2580 return put_user(excl, (int __user *)p);
2583 return tiocgetd(tty, p);
2585 return tiocsetd(tty, p);
2587 if (!capable(CAP_SYS_ADMIN))
2593 unsigned int ret = new_encode_dev(tty_devnum(real_tty));
2594 return put_user(ret, (unsigned int __user *)p);
2599 case TIOCSBRK: /* Turn break on, unconditionally */
2600 if (tty->ops->break_ctl)
2601 return tty->ops->break_ctl(tty, -1);
2603 case TIOCCBRK: /* Turn break off, unconditionally */
2604 if (tty->ops->break_ctl)
2605 return tty->ops->break_ctl(tty, 0);
2607 case TCSBRK: /* SVID version: non-zero arg --> no break */
2608 /* non-zero arg means wait for all output data
2609 * to be sent (performed above) but don't send break.
2610 * This is used by the tcdrain() termios function.
2613 return send_break(tty, 250);
2615 case TCSBRKP: /* support for POSIX tcsendbreak() */
2616 return send_break(tty, arg ? arg*100 : 250);
2619 return tty_tiocmget(tty, p);
2623 return tty_tiocmset(tty, cmd, p);
2625 retval = tty_tiocgicount(tty, p);
2626 /* For the moment allow fall through to the old method */
2627 if (retval != -EINVAL)
2634 /* flush tty buffer and allow ldisc to process ioctl */
2635 tty_buffer_flush(tty, NULL);
2640 tty_warn_deprecated_flags(p);
2643 /* Special because the struct file is needed */
2644 return ptm_open_peer(file, tty, (int)arg);
2646 retval = tty_jobctrl_ioctl(tty, real_tty, file, cmd, arg);
2647 if (retval != -ENOIOCTLCMD)
2650 if (tty->ops->ioctl) {
2651 retval = tty->ops->ioctl(tty, cmd, arg);
2652 if (retval != -ENOIOCTLCMD)
2655 ld = tty_ldisc_ref_wait(tty);
2657 return hung_up_tty_ioctl(file, cmd, arg);
2659 if (ld->ops->ioctl) {
2660 retval = ld->ops->ioctl(tty, file, cmd, arg);
2661 if (retval == -ENOIOCTLCMD)
2664 tty_ldisc_deref(ld);
2668 #ifdef CONFIG_COMPAT
2669 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2672 struct tty_struct *tty = file_tty(file);
2673 struct tty_ldisc *ld;
2674 int retval = -ENOIOCTLCMD;
2676 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2679 if (tty->ops->compat_ioctl) {
2680 retval = tty->ops->compat_ioctl(tty, cmd, arg);
2681 if (retval != -ENOIOCTLCMD)
2685 ld = tty_ldisc_ref_wait(tty);
2687 return hung_up_tty_compat_ioctl(file, cmd, arg);
2688 if (ld->ops->compat_ioctl)
2689 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
2691 retval = n_tty_compat_ioctl_helper(tty, file, cmd, arg);
2692 tty_ldisc_deref(ld);
2698 static int this_tty(const void *t, struct file *file, unsigned fd)
2700 if (likely(file->f_op->read != tty_read))
2702 return file_tty(file) != t ? 0 : fd + 1;
2706 * This implements the "Secure Attention Key" --- the idea is to
2707 * prevent trojan horses by killing all processes associated with this
2708 * tty when the user hits the "Secure Attention Key". Required for
2709 * super-paranoid applications --- see the Orange Book for more details.
2711 * This code could be nicer; ideally it should send a HUP, wait a few
2712 * seconds, then send a INT, and then a KILL signal. But you then
2713 * have to coordinate with the init process, since all processes associated
2714 * with the current tty must be dead before the new getty is allowed
2717 * Now, if it would be correct ;-/ The current code has a nasty hole -
2718 * it doesn't catch files in flight. We may send the descriptor to ourselves
2719 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
2721 * Nasty bug: do_SAK is being called in interrupt context. This can
2722 * deadlock. We punt it up to process context. AKPM - 16Mar2001
2724 void __do_SAK(struct tty_struct *tty)
2729 struct task_struct *g, *p;
2730 struct pid *session;
2735 session = tty->session;
2737 tty_ldisc_flush(tty);
2739 tty_driver_flush_buffer(tty);
2741 read_lock(&tasklist_lock);
2742 /* Kill the entire session */
2743 do_each_pid_task(session, PIDTYPE_SID, p) {
2744 tty_notice(tty, "SAK: killed process %d (%s): by session\n",
2745 task_pid_nr(p), p->comm);
2746 send_sig(SIGKILL, p, 1);
2747 } while_each_pid_task(session, PIDTYPE_SID, p);
2749 /* Now kill any processes that happen to have the tty open */
2750 do_each_thread(g, p) {
2751 if (p->signal->tty == tty) {
2752 tty_notice(tty, "SAK: killed process %d (%s): by controlling tty\n",
2753 task_pid_nr(p), p->comm);
2754 send_sig(SIGKILL, p, 1);
2758 i = iterate_fd(p->files, 0, this_tty, tty);
2760 tty_notice(tty, "SAK: killed process %d (%s): by fd#%d\n",
2761 task_pid_nr(p), p->comm, i - 1);
2762 force_sig(SIGKILL, p);
2765 } while_each_thread(g, p);
2766 read_unlock(&tasklist_lock);
2770 static void do_SAK_work(struct work_struct *work)
2772 struct tty_struct *tty =
2773 container_of(work, struct tty_struct, SAK_work);
2778 * The tq handling here is a little racy - tty->SAK_work may already be queued.
2779 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
2780 * the values which we write to it will be identical to the values which it
2781 * already has. --akpm
2783 void do_SAK(struct tty_struct *tty)
2787 schedule_work(&tty->SAK_work);
2790 EXPORT_SYMBOL(do_SAK);
2792 static int dev_match_devt(struct device *dev, const void *data)
2794 const dev_t *devt = data;
2795 return dev->devt == *devt;
2798 /* Must put_device() after it's unused! */
2799 static struct device *tty_get_device(struct tty_struct *tty)
2801 dev_t devt = tty_devnum(tty);
2802 return class_find_device(tty_class, NULL, &devt, dev_match_devt);
2809 * This subroutine allocates and initializes a tty structure.
2811 * Locking: none - tty in question is not exposed at this point
2814 struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
2816 struct tty_struct *tty;
2818 tty = kzalloc(sizeof(*tty), GFP_KERNEL);
2822 kref_init(&tty->kref);
2823 tty->magic = TTY_MAGIC;
2824 if (tty_ldisc_init(tty)) {
2828 tty->session = NULL;
2830 mutex_init(&tty->legacy_mutex);
2831 mutex_init(&tty->throttle_mutex);
2832 init_rwsem(&tty->termios_rwsem);
2833 mutex_init(&tty->winsize_mutex);
2834 init_ldsem(&tty->ldisc_sem);
2835 init_waitqueue_head(&tty->write_wait);
2836 init_waitqueue_head(&tty->read_wait);
2837 INIT_WORK(&tty->hangup_work, do_tty_hangup);
2838 mutex_init(&tty->atomic_write_lock);
2839 spin_lock_init(&tty->ctrl_lock);
2840 spin_lock_init(&tty->flow_lock);
2841 spin_lock_init(&tty->files_lock);
2842 INIT_LIST_HEAD(&tty->tty_files);
2843 INIT_WORK(&tty->SAK_work, do_SAK_work);
2845 tty->driver = driver;
2846 tty->ops = driver->ops;
2848 tty_line_name(driver, idx, tty->name);
2849 tty->dev = tty_get_device(tty);
2855 * tty_put_char - write one character to a tty
2859 * Write one byte to the tty using the provided put_char method
2860 * if present. Returns the number of characters successfully output.
2862 * Note: the specific put_char operation in the driver layer may go
2863 * away soon. Don't call it directly, use this method
2866 int tty_put_char(struct tty_struct *tty, unsigned char ch)
2868 if (tty->ops->put_char)
2869 return tty->ops->put_char(tty, ch);
2870 return tty->ops->write(tty, &ch, 1);
2872 EXPORT_SYMBOL_GPL(tty_put_char);
2874 struct class *tty_class;
2876 static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
2877 unsigned int index, unsigned int count)
2881 /* init here, since reused cdevs cause crashes */
2882 driver->cdevs[index] = cdev_alloc();
2883 if (!driver->cdevs[index])
2885 driver->cdevs[index]->ops = &tty_fops;
2886 driver->cdevs[index]->owner = driver->owner;
2887 err = cdev_add(driver->cdevs[index], dev, count);
2889 kobject_put(&driver->cdevs[index]->kobj);
2894 * tty_register_device - register a tty device
2895 * @driver: the tty driver that describes the tty device
2896 * @index: the index in the tty driver for this tty device
2897 * @device: a struct device that is associated with this tty device.
2898 * This field is optional, if there is no known struct device
2899 * for this tty device it can be set to NULL safely.
2901 * Returns a pointer to the struct device for this tty device
2902 * (or ERR_PTR(-EFOO) on error).
2904 * This call is required to be made to register an individual tty device
2905 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
2906 * that bit is not set, this function should not be called by a tty
2912 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
2913 struct device *device)
2915 return tty_register_device_attr(driver, index, device, NULL, NULL);
2917 EXPORT_SYMBOL(tty_register_device);
2919 static void tty_device_create_release(struct device *dev)
2921 dev_dbg(dev, "releasing...\n");
2926 * tty_register_device_attr - register a tty device
2927 * @driver: the tty driver that describes the tty device
2928 * @index: the index in the tty driver for this tty device
2929 * @device: a struct device that is associated with this tty device.
2930 * This field is optional, if there is no known struct device
2931 * for this tty device it can be set to NULL safely.
2932 * @drvdata: Driver data to be set to device.
2933 * @attr_grp: Attribute group to be set on device.
2935 * Returns a pointer to the struct device for this tty device
2936 * (or ERR_PTR(-EFOO) on error).
2938 * This call is required to be made to register an individual tty device
2939 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
2940 * that bit is not set, this function should not be called by a tty
2945 struct device *tty_register_device_attr(struct tty_driver *driver,
2946 unsigned index, struct device *device,
2948 const struct attribute_group **attr_grp)
2951 dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
2952 struct ktermios *tp;
2956 if (index >= driver->num) {
2957 pr_err("%s: Attempt to register invalid tty line number (%d)\n",
2958 driver->name, index);
2959 return ERR_PTR(-EINVAL);
2962 if (driver->type == TTY_DRIVER_TYPE_PTY)
2963 pty_line_name(driver, index, name);
2965 tty_line_name(driver, index, name);
2967 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
2969 return ERR_PTR(-ENOMEM);
2972 dev->class = tty_class;
2973 dev->parent = device;
2974 dev->release = tty_device_create_release;
2975 dev_set_name(dev, "%s", name);
2976 dev->groups = attr_grp;
2977 dev_set_drvdata(dev, drvdata);
2979 dev_set_uevent_suppress(dev, 1);
2981 retval = device_register(dev);
2985 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
2987 * Free any saved termios data so that the termios state is
2988 * reset when reusing a minor number.
2990 tp = driver->termios[index];
2992 driver->termios[index] = NULL;
2996 retval = tty_cdev_add(driver, devt, index, 1);
3001 dev_set_uevent_suppress(dev, 0);
3002 kobject_uevent(&dev->kobj, KOBJ_ADD);
3011 return ERR_PTR(retval);
3013 EXPORT_SYMBOL_GPL(tty_register_device_attr);
3016 * tty_unregister_device - unregister a tty device
3017 * @driver: the tty driver that describes the tty device
3018 * @index: the index in the tty driver for this tty device
3020 * If a tty device is registered with a call to tty_register_device() then
3021 * this function must be called when the tty device is gone.
3026 void tty_unregister_device(struct tty_driver *driver, unsigned index)
3028 device_destroy(tty_class,
3029 MKDEV(driver->major, driver->minor_start) + index);
3030 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3031 cdev_del(driver->cdevs[index]);
3032 driver->cdevs[index] = NULL;
3035 EXPORT_SYMBOL(tty_unregister_device);
3038 * __tty_alloc_driver -- allocate tty driver
3039 * @lines: count of lines this driver can handle at most
3040 * @owner: module which is responsible for this driver
3041 * @flags: some of TTY_DRIVER_* flags, will be set in driver->flags
3043 * This should not be called directly, some of the provided macros should be
3044 * used instead. Use IS_ERR and friends on @retval.
3046 struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
3047 unsigned long flags)
3049 struct tty_driver *driver;
3050 unsigned int cdevs = 1;
3053 if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
3054 return ERR_PTR(-EINVAL);
3056 driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
3058 return ERR_PTR(-ENOMEM);
3060 kref_init(&driver->kref);
3061 driver->magic = TTY_DRIVER_MAGIC;
3062 driver->num = lines;
3063 driver->owner = owner;
3064 driver->flags = flags;
3066 if (!(flags & TTY_DRIVER_DEVPTS_MEM)) {
3067 driver->ttys = kcalloc(lines, sizeof(*driver->ttys),
3069 driver->termios = kcalloc(lines, sizeof(*driver->termios),
3071 if (!driver->ttys || !driver->termios) {
3077 if (!(flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3078 driver->ports = kcalloc(lines, sizeof(*driver->ports),
3080 if (!driver->ports) {
3087 driver->cdevs = kcalloc(cdevs, sizeof(*driver->cdevs), GFP_KERNEL);
3088 if (!driver->cdevs) {
3095 kfree(driver->ports);
3096 kfree(driver->ttys);
3097 kfree(driver->termios);
3098 kfree(driver->cdevs);
3100 return ERR_PTR(err);
3102 EXPORT_SYMBOL(__tty_alloc_driver);
3104 static void destruct_tty_driver(struct kref *kref)
3106 struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
3108 struct ktermios *tp;
3110 if (driver->flags & TTY_DRIVER_INSTALLED) {
3111 for (i = 0; i < driver->num; i++) {
3112 tp = driver->termios[i];
3114 driver->termios[i] = NULL;
3117 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3118 tty_unregister_device(driver, i);
3120 proc_tty_unregister_driver(driver);
3121 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
3122 cdev_del(driver->cdevs[0]);
3124 kfree(driver->cdevs);
3125 kfree(driver->ports);
3126 kfree(driver->termios);
3127 kfree(driver->ttys);
3131 void tty_driver_kref_put(struct tty_driver *driver)
3133 kref_put(&driver->kref, destruct_tty_driver);
3135 EXPORT_SYMBOL(tty_driver_kref_put);
3137 void tty_set_operations(struct tty_driver *driver,
3138 const struct tty_operations *op)
3142 EXPORT_SYMBOL(tty_set_operations);
3144 void put_tty_driver(struct tty_driver *d)
3146 tty_driver_kref_put(d);
3148 EXPORT_SYMBOL(put_tty_driver);
3151 * Called by a tty driver to register itself.
3153 int tty_register_driver(struct tty_driver *driver)
3160 if (!driver->major) {
3161 error = alloc_chrdev_region(&dev, driver->minor_start,
3162 driver->num, driver->name);
3164 driver->major = MAJOR(dev);
3165 driver->minor_start = MINOR(dev);
3168 dev = MKDEV(driver->major, driver->minor_start);
3169 error = register_chrdev_region(dev, driver->num, driver->name);
3174 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) {
3175 error = tty_cdev_add(driver, dev, 0, driver->num);
3177 goto err_unreg_char;
3180 mutex_lock(&tty_mutex);
3181 list_add(&driver->tty_drivers, &tty_drivers);
3182 mutex_unlock(&tty_mutex);
3184 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
3185 for (i = 0; i < driver->num; i++) {
3186 d = tty_register_device(driver, i, NULL);
3189 goto err_unreg_devs;
3193 proc_tty_register_driver(driver);
3194 driver->flags |= TTY_DRIVER_INSTALLED;
3198 for (i--; i >= 0; i--)
3199 tty_unregister_device(driver, i);
3201 mutex_lock(&tty_mutex);
3202 list_del(&driver->tty_drivers);
3203 mutex_unlock(&tty_mutex);
3206 unregister_chrdev_region(dev, driver->num);
3210 EXPORT_SYMBOL(tty_register_driver);
3213 * Called by a tty driver to unregister itself.
3215 int tty_unregister_driver(struct tty_driver *driver)
3219 if (driver->refcount)
3222 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3224 mutex_lock(&tty_mutex);
3225 list_del(&driver->tty_drivers);
3226 mutex_unlock(&tty_mutex);
3230 EXPORT_SYMBOL(tty_unregister_driver);
3232 dev_t tty_devnum(struct tty_struct *tty)
3234 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3236 EXPORT_SYMBOL(tty_devnum);
3238 void tty_default_fops(struct file_operations *fops)
3243 static char *tty_devnode(struct device *dev, umode_t *mode)
3247 if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
3248 dev->devt == MKDEV(TTYAUX_MAJOR, 2))
3253 static int __init tty_class_init(void)
3255 tty_class = class_create(THIS_MODULE, "tty");
3256 if (IS_ERR(tty_class))
3257 return PTR_ERR(tty_class);
3258 tty_class->devnode = tty_devnode;
3262 postcore_initcall(tty_class_init);
3264 /* 3/2004 jmc: why do these devices exist? */
3265 static struct cdev tty_cdev, console_cdev;
3267 static ssize_t show_cons_active(struct device *dev,
3268 struct device_attribute *attr, char *buf)
3270 struct console *cs[16];
3276 for_each_console(c) {
3281 if ((c->flags & CON_ENABLED) == 0)
3284 if (i >= ARRAY_SIZE(cs))
3288 int index = cs[i]->index;
3289 struct tty_driver *drv = cs[i]->device(cs[i], &index);
3291 /* don't resolve tty0 as some programs depend on it */
3292 if (drv && (cs[i]->index > 0 || drv->major != TTY_MAJOR))
3293 count += tty_line_name(drv, index, buf + count);
3295 count += sprintf(buf + count, "%s%d",
3296 cs[i]->name, cs[i]->index);
3298 count += sprintf(buf + count, "%c", i ? ' ':'\n');
3304 static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
3306 static struct attribute *cons_dev_attrs[] = {
3307 &dev_attr_active.attr,
3311 ATTRIBUTE_GROUPS(cons_dev);
3313 static struct device *consdev;
3315 void console_sysfs_notify(void)
3318 sysfs_notify(&consdev->kobj, NULL, "active");
3322 * Ok, now we can initialize the rest of the tty devices and can count
3323 * on memory allocations, interrupts etc..
3325 int __init tty_init(void)
3327 cdev_init(&tty_cdev, &tty_fops);
3328 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3329 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3330 panic("Couldn't register /dev/tty driver\n");
3331 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
3333 cdev_init(&console_cdev, &console_fops);
3334 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3335 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3336 panic("Couldn't register /dev/console driver\n");
3337 consdev = device_create_with_groups(tty_class, NULL,
3338 MKDEV(TTYAUX_MAJOR, 1), NULL,
3339 cons_dev_groups, "console");
3340 if (IS_ERR(consdev))
3344 vty_init(&console_fops);