2 * linux/drivers/char/tty_io.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
8 * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles
9 * or rs-channels. It also implements echoing, cooked mode etc.
11 * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.
13 * Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the
14 * tty_struct and tty_queue structures. Previously there was an array
15 * of 256 tty_struct's which was statically allocated, and the
16 * tty_queue structures were allocated at boot time. Both are now
17 * dynamically allocated only when the tty is open.
19 * Also restructured routines so that there is more of a separation
20 * between the high-level tty routines (tty_io.c and tty_ioctl.c) and
21 * the low-level tty routines (serial.c, pty.c, console.c). This
22 * makes for cleaner and more compact code. -TYT, 9/17/92
24 * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
25 * which can be dynamically activated and de-activated by the line
26 * discipline handling modules (like SLIP).
28 * NOTE: pay no attention to the line discipline code (yet); its
29 * interface is still subject to change in this version...
32 * Added functionality to the OPOST tty handling. No delays, but all
33 * other bits should be there.
34 * -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993.
36 * Rewrote canonical mode and added more termios flags.
37 * -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94
39 * Reorganized FASYNC support so mouse code can share it.
40 * -- ctm@ardi.com, 9Sep95
42 * New TIOCLINUX variants added.
43 * -- mj@k332.feld.cvut.cz, 19-Nov-95
45 * Restrict vt switching via ioctl()
46 * -- grif@cs.ucr.edu, 5-Dec-95
48 * Move console and virtual terminal code to more appropriate files,
49 * implement CONFIG_VT and generalize console device interface.
50 * -- Marko Kohtala <Marko.Kohtala@hut.fi>, March 97
52 * Rewrote init_dev and release_dev to eliminate races.
53 * -- Bill Hawes <whawes@star.net>, June 97
55 * Added devfs support.
56 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 13-Jan-1998
58 * Added support for a Unix98-style ptmx device.
59 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
61 * Reduced memory usage for older ARM systems
62 * -- Russell King <rmk@arm.linux.org.uk>
64 * Move do_SAK() into process context. Less stack use in devfs functions.
65 * alloc_tty_struct() always uses kmalloc() -- 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.h>
74 #include <linux/interrupt.h>
75 #include <linux/tty.h>
76 #include <linux/tty_driver.h>
77 #include <linux/tty_flip.h>
78 #include <linux/devpts_fs.h>
79 #include <linux/file.h>
80 #include <linux/console.h>
81 #include <linux/timer.h>
82 #include <linux/ctype.h>
85 #include <linux/string.h>
86 #include <linux/slab.h>
87 #include <linux/poll.h>
88 #include <linux/proc_fs.h>
89 #include <linux/init.h>
90 #include <linux/module.h>
91 #include <linux/smp_lock.h>
92 #include <linux/device.h>
93 #include <linux/idr.h>
94 #include <linux/wait.h>
95 #include <linux/bitops.h>
96 #include <linux/delay.h>
98 #include <asm/uaccess.h>
99 #include <asm/system.h>
101 #include <linux/kbd_kern.h>
102 #include <linux/vt_kern.h>
103 #include <linux/selection.h>
105 #include <linux/kmod.h>
107 #undef TTY_DEBUG_HANGUP
109 #define TTY_PARANOIA_CHECK 1
110 #define CHECK_TTY_COUNT 1
112 struct ktermios tty_std_termios = { /* for the benefit of tty drivers */
113 .c_iflag = ICRNL | IXON,
114 .c_oflag = OPOST | ONLCR,
115 .c_cflag = B38400 | CS8 | CREAD | HUPCL,
116 .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
117 ECHOCTL | ECHOKE | IEXTEN,
123 EXPORT_SYMBOL(tty_std_termios);
125 /* This list gets poked at by procfs and various bits of boot up code. This
126 could do with some rationalisation such as pulling the tty proc function
129 LIST_HEAD(tty_drivers); /* linked list of tty drivers */
131 /* Mutex to protect creating and releasing a tty. This is shared with
132 vt.c for deeply disgusting hack reasons */
133 DEFINE_MUTEX(tty_mutex);
134 EXPORT_SYMBOL(tty_mutex);
136 #ifdef CONFIG_UNIX98_PTYS
137 extern struct tty_driver *ptm_driver; /* Unix98 pty masters; for /dev/ptmx */
138 extern int pty_limit; /* Config limit on Unix98 ptys */
139 static DEFINE_IDR(allocated_ptys);
140 static DECLARE_MUTEX(allocated_ptys_lock);
141 static int ptmx_open(struct inode *, struct file *);
144 extern void disable_early_printk(void);
146 static void initialize_tty_struct(struct tty_struct *tty);
148 static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
149 static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
150 ssize_t redirected_tty_write(struct file *, const char __user *, size_t, loff_t *);
151 static unsigned int tty_poll(struct file *, poll_table *);
152 static int tty_open(struct inode *, struct file *);
153 static int tty_release(struct inode *, struct file *);
154 int tty_ioctl(struct inode * inode, struct file * file,
155 unsigned int cmd, unsigned long arg);
156 static int tty_fasync(int fd, struct file * filp, int on);
157 static void release_tty(struct tty_struct *tty, int idx);
158 static struct pid *__proc_set_tty(struct task_struct *tsk,
159 struct tty_struct *tty);
162 * alloc_tty_struct - allocate a tty object
164 * Return a new empty tty structure. The data fields have not
165 * been initialized in any way but has been zeroed
170 static struct tty_struct *alloc_tty_struct(void)
172 return kzalloc(sizeof(struct tty_struct), GFP_KERNEL);
175 static void tty_buffer_free_all(struct tty_struct *);
178 * free_tty_struct - free a disused tty
179 * @tty: tty struct to free
181 * Free the write buffers, tty queue and tty memory itself.
183 * Locking: none. Must be called after tty is definitely unused
186 static inline void free_tty_struct(struct tty_struct *tty)
188 kfree(tty->write_buf);
189 tty_buffer_free_all(tty);
193 #define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base)
196 * tty_name - return tty naming
197 * @tty: tty structure
198 * @buf: buffer for output
200 * Convert a tty structure into a name. The name reflects the kernel
201 * naming policy and if udev is in use may not reflect user space
206 char *tty_name(struct tty_struct *tty, char *buf)
208 if (!tty) /* Hmm. NULL pointer. That's fun. */
209 strcpy(buf, "NULL tty");
211 strcpy(buf, tty->name);
215 EXPORT_SYMBOL(tty_name);
217 int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
220 #ifdef TTY_PARANOIA_CHECK
223 "null TTY for (%d:%d) in %s\n",
224 imajor(inode), iminor(inode), routine);
227 if (tty->magic != TTY_MAGIC) {
229 "bad magic number for tty struct (%d:%d) in %s\n",
230 imajor(inode), iminor(inode), routine);
237 static int check_tty_count(struct tty_struct *tty, const char *routine)
239 #ifdef CHECK_TTY_COUNT
244 list_for_each(p, &tty->tty_files) {
248 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
249 tty->driver->subtype == PTY_TYPE_SLAVE &&
250 tty->link && tty->link->count)
252 if (tty->count != count) {
253 printk(KERN_WARNING "Warning: dev (%s) tty->count(%d) "
254 "!= #fd's(%d) in %s\n",
255 tty->name, tty->count, count, routine);
263 * Tty buffer allocation management
267 * tty_buffer_free_all - free buffers used by a tty
268 * @tty: tty to free from
270 * Remove all the buffers pending on a tty whether queued with data
271 * or in the free ring. Must be called when the tty is no longer in use
276 static void tty_buffer_free_all(struct tty_struct *tty)
278 struct tty_buffer *thead;
279 while((thead = tty->buf.head) != NULL) {
280 tty->buf.head = thead->next;
283 while((thead = tty->buf.free) != NULL) {
284 tty->buf.free = thead->next;
287 tty->buf.tail = NULL;
288 tty->buf.memory_used = 0;
292 * tty_buffer_init - prepare a tty buffer structure
293 * @tty: tty to initialise
295 * Set up the initial state of the buffer management for a tty device.
296 * Must be called before the other tty buffer functions are used.
301 static void tty_buffer_init(struct tty_struct *tty)
303 spin_lock_init(&tty->buf.lock);
304 tty->buf.head = NULL;
305 tty->buf.tail = NULL;
306 tty->buf.free = NULL;
307 tty->buf.memory_used = 0;
311 * tty_buffer_alloc - allocate a tty buffer
313 * @size: desired size (characters)
315 * Allocate a new tty buffer to hold the desired number of characters.
316 * Return NULL if out of memory or the allocation would exceed the
319 * Locking: Caller must hold tty->buf.lock
322 static struct tty_buffer *tty_buffer_alloc(struct tty_struct *tty, size_t size)
324 struct tty_buffer *p;
326 if (tty->buf.memory_used + size > 65536)
328 p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC);
336 p->char_buf_ptr = (char *)(p->data);
337 p->flag_buf_ptr = (unsigned char *)p->char_buf_ptr + size;
338 tty->buf.memory_used += size;
343 * tty_buffer_free - free a tty buffer
344 * @tty: tty owning the buffer
345 * @b: the buffer to free
347 * Free a tty buffer, or add it to the free list according to our
350 * Locking: Caller must hold tty->buf.lock
353 static void tty_buffer_free(struct tty_struct *tty, struct tty_buffer *b)
355 /* Dumb strategy for now - should keep some stats */
356 tty->buf.memory_used -= b->size;
357 WARN_ON(tty->buf.memory_used < 0);
362 b->next = tty->buf.free;
368 * tty_buffer_find - find a free tty buffer
369 * @tty: tty owning the buffer
370 * @size: characters wanted
372 * Locate an existing suitable tty buffer or if we are lacking one then
373 * allocate a new one. We round our buffers off in 256 character chunks
374 * to get better allocation behaviour.
376 * Locking: Caller must hold tty->buf.lock
379 static struct tty_buffer *tty_buffer_find(struct tty_struct *tty, size_t size)
381 struct tty_buffer **tbh = &tty->buf.free;
382 while((*tbh) != NULL) {
383 struct tty_buffer *t = *tbh;
384 if(t->size >= size) {
390 tty->buf.memory_used += t->size;
393 tbh = &((*tbh)->next);
395 /* Round the buffer size out */
396 size = (size + 0xFF) & ~ 0xFF;
397 return tty_buffer_alloc(tty, size);
398 /* Should possibly check if this fails for the largest buffer we
399 have queued and recycle that ? */
403 * tty_buffer_request_room - grow tty buffer if needed
404 * @tty: tty structure
405 * @size: size desired
407 * Make at least size bytes of linear space available for the tty
408 * buffer. If we fail return the size we managed to find.
410 * Locking: Takes tty->buf.lock
412 int tty_buffer_request_room(struct tty_struct *tty, size_t size)
414 struct tty_buffer *b, *n;
418 spin_lock_irqsave(&tty->buf.lock, flags);
420 /* OPTIMISATION: We could keep a per tty "zero" sized buffer to
421 remove this conditional if its worth it. This would be invisible
423 if ((b = tty->buf.tail) != NULL)
424 left = b->size - b->used;
429 /* This is the slow path - looking for new buffers to use */
430 if ((n = tty_buffer_find(tty, size)) != NULL) {
441 spin_unlock_irqrestore(&tty->buf.lock, flags);
444 EXPORT_SYMBOL_GPL(tty_buffer_request_room);
447 * tty_insert_flip_string - Add characters to the tty buffer
448 * @tty: tty structure
452 * Queue a series of bytes to the tty buffering. All the characters
453 * passed are marked as without error. Returns the number added.
455 * Locking: Called functions may take tty->buf.lock
458 int tty_insert_flip_string(struct tty_struct *tty, const unsigned char *chars,
463 int space = tty_buffer_request_room(tty, size - copied);
464 struct tty_buffer *tb = tty->buf.tail;
465 /* If there is no space then tb may be NULL */
466 if(unlikely(space == 0))
468 memcpy(tb->char_buf_ptr + tb->used, chars, space);
469 memset(tb->flag_buf_ptr + tb->used, TTY_NORMAL, space);
473 /* There is a small chance that we need to split the data over
474 several buffers. If this is the case we must loop */
475 } while (unlikely(size > copied));
478 EXPORT_SYMBOL(tty_insert_flip_string);
481 * tty_insert_flip_string_flags - Add characters to the tty buffer
482 * @tty: tty structure
487 * Queue a series of bytes to the tty buffering. For each character
488 * the flags array indicates the status of the character. Returns the
491 * Locking: Called functions may take tty->buf.lock
494 int tty_insert_flip_string_flags(struct tty_struct *tty,
495 const unsigned char *chars, const char *flags, size_t size)
499 int space = tty_buffer_request_room(tty, size - copied);
500 struct tty_buffer *tb = tty->buf.tail;
501 /* If there is no space then tb may be NULL */
502 if(unlikely(space == 0))
504 memcpy(tb->char_buf_ptr + tb->used, chars, space);
505 memcpy(tb->flag_buf_ptr + tb->used, flags, space);
510 /* There is a small chance that we need to split the data over
511 several buffers. If this is the case we must loop */
512 } while (unlikely(size > copied));
515 EXPORT_SYMBOL(tty_insert_flip_string_flags);
518 * tty_schedule_flip - push characters to ldisc
519 * @tty: tty to push from
521 * Takes any pending buffers and transfers their ownership to the
522 * ldisc side of the queue. It then schedules those characters for
523 * processing by the line discipline.
525 * Locking: Takes tty->buf.lock
528 void tty_schedule_flip(struct tty_struct *tty)
531 spin_lock_irqsave(&tty->buf.lock, flags);
532 if (tty->buf.tail != NULL)
533 tty->buf.tail->commit = tty->buf.tail->used;
534 spin_unlock_irqrestore(&tty->buf.lock, flags);
535 schedule_delayed_work(&tty->buf.work, 1);
537 EXPORT_SYMBOL(tty_schedule_flip);
540 * tty_prepare_flip_string - make room for characters
542 * @chars: return pointer for character write area
543 * @size: desired size
545 * Prepare a block of space in the buffer for data. Returns the length
546 * available and buffer pointer to the space which is now allocated and
547 * accounted for as ready for normal characters. This is used for drivers
548 * that need their own block copy routines into the buffer. There is no
549 * guarantee the buffer is a DMA target!
551 * Locking: May call functions taking tty->buf.lock
554 int tty_prepare_flip_string(struct tty_struct *tty, unsigned char **chars, size_t size)
556 int space = tty_buffer_request_room(tty, size);
558 struct tty_buffer *tb = tty->buf.tail;
559 *chars = tb->char_buf_ptr + tb->used;
560 memset(tb->flag_buf_ptr + tb->used, TTY_NORMAL, space);
566 EXPORT_SYMBOL_GPL(tty_prepare_flip_string);
569 * tty_prepare_flip_string_flags - make room for characters
571 * @chars: return pointer for character write area
572 * @flags: return pointer for status flag write area
573 * @size: desired size
575 * Prepare a block of space in the buffer for data. Returns the length
576 * available and buffer pointer to the space which is now allocated and
577 * accounted for as ready for characters. This is used for drivers
578 * that need their own block copy routines into the buffer. There is no
579 * guarantee the buffer is a DMA target!
581 * Locking: May call functions taking tty->buf.lock
584 int tty_prepare_flip_string_flags(struct tty_struct *tty, unsigned char **chars, char **flags, size_t size)
586 int space = tty_buffer_request_room(tty, size);
588 struct tty_buffer *tb = tty->buf.tail;
589 *chars = tb->char_buf_ptr + tb->used;
590 *flags = tb->flag_buf_ptr + tb->used;
596 EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags);
601 * tty_set_termios_ldisc - set ldisc field
602 * @tty: tty structure
603 * @num: line discipline number
605 * This is probably overkill for real world processors but
606 * they are not on hot paths so a little discipline won't do
609 * Locking: takes termios_mutex
612 static void tty_set_termios_ldisc(struct tty_struct *tty, int num)
614 mutex_lock(&tty->termios_mutex);
615 tty->termios->c_line = num;
616 mutex_unlock(&tty->termios_mutex);
620 * This guards the refcounted line discipline lists. The lock
621 * must be taken with irqs off because there are hangup path
622 * callers who will do ldisc lookups and cannot sleep.
625 static DEFINE_SPINLOCK(tty_ldisc_lock);
626 static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_wait);
627 static struct tty_ldisc tty_ldiscs[NR_LDISCS]; /* line disc dispatch table */
630 * tty_register_ldisc - install a line discipline
631 * @disc: ldisc number
632 * @new_ldisc: pointer to the ldisc object
634 * Installs a new line discipline into the kernel. The discipline
635 * is set up as unreferenced and then made available to the kernel
636 * from this point onwards.
639 * takes tty_ldisc_lock to guard against ldisc races
642 int tty_register_ldisc(int disc, struct tty_ldisc *new_ldisc)
647 if (disc < N_TTY || disc >= NR_LDISCS)
650 spin_lock_irqsave(&tty_ldisc_lock, flags);
651 tty_ldiscs[disc] = *new_ldisc;
652 tty_ldiscs[disc].num = disc;
653 tty_ldiscs[disc].flags |= LDISC_FLAG_DEFINED;
654 tty_ldiscs[disc].refcount = 0;
655 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
659 EXPORT_SYMBOL(tty_register_ldisc);
662 * tty_unregister_ldisc - unload a line discipline
663 * @disc: ldisc number
664 * @new_ldisc: pointer to the ldisc object
666 * Remove a line discipline from the kernel providing it is not
670 * takes tty_ldisc_lock to guard against ldisc races
673 int tty_unregister_ldisc(int disc)
678 if (disc < N_TTY || disc >= NR_LDISCS)
681 spin_lock_irqsave(&tty_ldisc_lock, flags);
682 if (tty_ldiscs[disc].refcount)
685 tty_ldiscs[disc].flags &= ~LDISC_FLAG_DEFINED;
686 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
690 EXPORT_SYMBOL(tty_unregister_ldisc);
693 * tty_ldisc_get - take a reference to an ldisc
694 * @disc: ldisc number
696 * Takes a reference to a line discipline. Deals with refcounts and
697 * module locking counts. Returns NULL if the discipline is not available.
698 * Returns a pointer to the discipline and bumps the ref count if it is
702 * takes tty_ldisc_lock to guard against ldisc races
705 struct tty_ldisc *tty_ldisc_get(int disc)
708 struct tty_ldisc *ld;
710 if (disc < N_TTY || disc >= NR_LDISCS)
713 spin_lock_irqsave(&tty_ldisc_lock, flags);
715 ld = &tty_ldiscs[disc];
716 /* Check the entry is defined */
717 if(ld->flags & LDISC_FLAG_DEFINED)
719 /* If the module is being unloaded we can't use it */
720 if (!try_module_get(ld->owner))
727 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
731 EXPORT_SYMBOL_GPL(tty_ldisc_get);
734 * tty_ldisc_put - drop ldisc reference
735 * @disc: ldisc number
737 * Drop a reference to a line discipline. Manage refcounts and
738 * module usage counts
741 * takes tty_ldisc_lock to guard against ldisc races
744 void tty_ldisc_put(int disc)
746 struct tty_ldisc *ld;
749 BUG_ON(disc < N_TTY || disc >= NR_LDISCS);
751 spin_lock_irqsave(&tty_ldisc_lock, flags);
752 ld = &tty_ldiscs[disc];
753 BUG_ON(ld->refcount == 0);
755 module_put(ld->owner);
756 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
759 EXPORT_SYMBOL_GPL(tty_ldisc_put);
762 * tty_ldisc_assign - set ldisc on a tty
763 * @tty: tty to assign
764 * @ld: line discipline
766 * Install an instance of a line discipline into a tty structure. The
767 * ldisc must have a reference count above zero to ensure it remains/
768 * The tty instance refcount starts at zero.
771 * Caller must hold references
774 static void tty_ldisc_assign(struct tty_struct *tty, struct tty_ldisc *ld)
777 tty->ldisc.refcount = 0;
781 * tty_ldisc_try - internal helper
784 * Make a single attempt to grab and bump the refcount on
785 * the tty ldisc. Return 0 on failure or 1 on success. This is
786 * used to implement both the waiting and non waiting versions
789 * Locking: takes tty_ldisc_lock
792 static int tty_ldisc_try(struct tty_struct *tty)
795 struct tty_ldisc *ld;
798 spin_lock_irqsave(&tty_ldisc_lock, flags);
800 if(test_bit(TTY_LDISC, &tty->flags))
805 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
810 * tty_ldisc_ref_wait - wait for the tty ldisc
813 * Dereference the line discipline for the terminal and take a
814 * reference to it. If the line discipline is in flux then
815 * wait patiently until it changes.
817 * Note: Must not be called from an IRQ/timer context. The caller
818 * must also be careful not to hold other locks that will deadlock
819 * against a discipline change, such as an existing ldisc reference
820 * (which we check for)
822 * Locking: call functions take tty_ldisc_lock
825 struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty)
827 /* wait_event is a macro */
828 wait_event(tty_ldisc_wait, tty_ldisc_try(tty));
829 if(tty->ldisc.refcount == 0)
830 printk(KERN_ERR "tty_ldisc_ref_wait\n");
834 EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait);
837 * tty_ldisc_ref - get the tty ldisc
840 * Dereference the line discipline for the terminal and take a
841 * reference to it. If the line discipline is in flux then
842 * return NULL. Can be called from IRQ and timer functions.
844 * Locking: called functions take tty_ldisc_lock
847 struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty)
849 if(tty_ldisc_try(tty))
854 EXPORT_SYMBOL_GPL(tty_ldisc_ref);
857 * tty_ldisc_deref - free a tty ldisc reference
858 * @ld: reference to free up
860 * Undoes the effect of tty_ldisc_ref or tty_ldisc_ref_wait. May
861 * be called in IRQ context.
863 * Locking: takes tty_ldisc_lock
866 void tty_ldisc_deref(struct tty_ldisc *ld)
872 spin_lock_irqsave(&tty_ldisc_lock, flags);
873 if(ld->refcount == 0)
874 printk(KERN_ERR "tty_ldisc_deref: no references.\n");
877 if(ld->refcount == 0)
878 wake_up(&tty_ldisc_wait);
879 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
882 EXPORT_SYMBOL_GPL(tty_ldisc_deref);
885 * tty_ldisc_enable - allow ldisc use
886 * @tty: terminal to activate ldisc on
888 * Set the TTY_LDISC flag when the line discipline can be called
889 * again. Do neccessary wakeups for existing sleepers.
891 * Note: nobody should set this bit except via this function. Clearing
892 * directly is allowed.
895 static void tty_ldisc_enable(struct tty_struct *tty)
897 set_bit(TTY_LDISC, &tty->flags);
898 wake_up(&tty_ldisc_wait);
902 * tty_set_ldisc - set line discipline
903 * @tty: the terminal to set
904 * @ldisc: the line discipline
906 * Set the discipline of a tty line. Must be called from a process
909 * Locking: takes tty_ldisc_lock.
910 * called functions take termios_mutex
913 static int tty_set_ldisc(struct tty_struct *tty, int ldisc)
916 struct tty_ldisc o_ldisc;
920 struct tty_ldisc *ld;
921 struct tty_struct *o_tty;
923 if ((ldisc < N_TTY) || (ldisc >= NR_LDISCS))
928 ld = tty_ldisc_get(ldisc);
929 /* Eduardo Blanco <ejbs@cs.cs.com.uy> */
930 /* Cyrus Durgin <cider@speakeasy.org> */
932 request_module("tty-ldisc-%d", ldisc);
933 ld = tty_ldisc_get(ldisc);
939 * No more input please, we are switching. The new ldisc
940 * will update this value in the ldisc open function
943 tty->receive_room = 0;
946 * Problem: What do we do if this blocks ?
949 tty_wait_until_sent(tty, 0);
951 if (tty->ldisc.num == ldisc) {
952 tty_ldisc_put(ldisc);
956 o_ldisc = tty->ldisc;
960 * Make sure we don't change while someone holds a
961 * reference to the line discipline. The TTY_LDISC bit
962 * prevents anyone taking a reference once it is clear.
963 * We need the lock to avoid racing reference takers.
966 spin_lock_irqsave(&tty_ldisc_lock, flags);
967 if (tty->ldisc.refcount || (o_tty && o_tty->ldisc.refcount)) {
968 if(tty->ldisc.refcount) {
969 /* Free the new ldisc we grabbed. Must drop the lock
971 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
972 tty_ldisc_put(ldisc);
974 * There are several reasons we may be busy, including
975 * random momentary I/O traffic. We must therefore
976 * retry. We could distinguish between blocking ops
977 * and retries if we made tty_ldisc_wait() smarter. That
978 * is up for discussion.
980 if (wait_event_interruptible(tty_ldisc_wait, tty->ldisc.refcount == 0) < 0)
984 if(o_tty && o_tty->ldisc.refcount) {
985 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
986 tty_ldisc_put(ldisc);
987 if (wait_event_interruptible(tty_ldisc_wait, o_tty->ldisc.refcount == 0) < 0)
993 /* if the TTY_LDISC bit is set, then we are racing against another ldisc change */
995 if (!test_bit(TTY_LDISC, &tty->flags)) {
996 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
997 tty_ldisc_put(ldisc);
998 ld = tty_ldisc_ref_wait(tty);
1003 clear_bit(TTY_LDISC, &tty->flags);
1005 clear_bit(TTY_LDISC, &o_tty->flags);
1006 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
1009 * From this point on we know nobody has an ldisc
1010 * usage reference, nor can they obtain one until
1011 * we say so later on.
1014 work = cancel_delayed_work(&tty->buf.work);
1016 * Wait for ->hangup_work and ->buf.work handlers to terminate
1019 flush_scheduled_work();
1020 /* Shutdown the current discipline. */
1021 if (tty->ldisc.close)
1022 (tty->ldisc.close)(tty);
1024 /* Now set up the new line discipline. */
1025 tty_ldisc_assign(tty, ld);
1026 tty_set_termios_ldisc(tty, ldisc);
1027 if (tty->ldisc.open)
1028 retval = (tty->ldisc.open)(tty);
1030 tty_ldisc_put(ldisc);
1031 /* There is an outstanding reference here so this is safe */
1032 tty_ldisc_assign(tty, tty_ldisc_get(o_ldisc.num));
1033 tty_set_termios_ldisc(tty, tty->ldisc.num);
1034 if (tty->ldisc.open && (tty->ldisc.open(tty) < 0)) {
1035 tty_ldisc_put(o_ldisc.num);
1036 /* This driver is always present */
1037 tty_ldisc_assign(tty, tty_ldisc_get(N_TTY));
1038 tty_set_termios_ldisc(tty, N_TTY);
1039 if (tty->ldisc.open) {
1040 int r = tty->ldisc.open(tty);
1043 panic("Couldn't open N_TTY ldisc for "
1045 tty_name(tty, buf), r);
1049 /* At this point we hold a reference to the new ldisc and a
1050 a reference to the old ldisc. If we ended up flipping back
1051 to the existing ldisc we have two references to it */
1053 if (tty->ldisc.num != o_ldisc.num && tty->driver->set_ldisc)
1054 tty->driver->set_ldisc(tty);
1056 tty_ldisc_put(o_ldisc.num);
1059 * Allow ldisc referencing to occur as soon as the driver
1060 * ldisc callback completes.
1063 tty_ldisc_enable(tty);
1065 tty_ldisc_enable(o_tty);
1067 /* Restart it in case no characters kick it off. Safe if
1070 schedule_delayed_work(&tty->buf.work, 1);
1075 * get_tty_driver - find device of a tty
1076 * @dev_t: device identifier
1077 * @index: returns the index of the tty
1079 * This routine returns a tty driver structure, given a device number
1080 * and also passes back the index number.
1082 * Locking: caller must hold tty_mutex
1085 static struct tty_driver *get_tty_driver(dev_t device, int *index)
1087 struct tty_driver *p;
1089 list_for_each_entry(p, &tty_drivers, tty_drivers) {
1090 dev_t base = MKDEV(p->major, p->minor_start);
1091 if (device < base || device >= base + p->num)
1093 *index = device - base;
1100 * tty_check_change - check for POSIX terminal changes
1101 * @tty: tty to check
1103 * If we try to write to, or set the state of, a terminal and we're
1104 * not in the foreground, send a SIGTTOU. If the signal is blocked or
1105 * ignored, go ahead and perform the operation. (POSIX 7.2)
1110 int tty_check_change(struct tty_struct * tty)
1112 if (current->signal->tty != tty)
1115 printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");
1118 if (task_pgrp(current) == tty->pgrp)
1120 if (is_ignored(SIGTTOU))
1122 if (is_current_pgrp_orphaned())
1124 (void) kill_pgrp(task_pgrp(current), SIGTTOU, 1);
1125 return -ERESTARTSYS;
1128 EXPORT_SYMBOL(tty_check_change);
1130 static ssize_t hung_up_tty_read(struct file * file, char __user * buf,
1131 size_t count, loff_t *ppos)
1136 static ssize_t hung_up_tty_write(struct file * file, const char __user * buf,
1137 size_t count, loff_t *ppos)
1142 /* No kernel lock held - none needed ;) */
1143 static unsigned int hung_up_tty_poll(struct file * filp, poll_table * wait)
1145 return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM;
1148 static int hung_up_tty_ioctl(struct inode * inode, struct file * file,
1149 unsigned int cmd, unsigned long arg)
1151 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
1154 static const struct file_operations tty_fops = {
1155 .llseek = no_llseek,
1161 .release = tty_release,
1162 .fasync = tty_fasync,
1165 #ifdef CONFIG_UNIX98_PTYS
1166 static const struct file_operations ptmx_fops = {
1167 .llseek = no_llseek,
1173 .release = tty_release,
1174 .fasync = tty_fasync,
1178 static const struct file_operations console_fops = {
1179 .llseek = no_llseek,
1181 .write = redirected_tty_write,
1185 .release = tty_release,
1186 .fasync = tty_fasync,
1189 static const struct file_operations hung_up_tty_fops = {
1190 .llseek = no_llseek,
1191 .read = hung_up_tty_read,
1192 .write = hung_up_tty_write,
1193 .poll = hung_up_tty_poll,
1194 .ioctl = hung_up_tty_ioctl,
1195 .release = tty_release,
1198 static DEFINE_SPINLOCK(redirect_lock);
1199 static struct file *redirect;
1202 * tty_wakeup - request more data
1205 * Internal and external helper for wakeups of tty. This function
1206 * informs the line discipline if present that the driver is ready
1207 * to receive more output data.
1210 void tty_wakeup(struct tty_struct *tty)
1212 struct tty_ldisc *ld;
1214 if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
1215 ld = tty_ldisc_ref(tty);
1217 if(ld->write_wakeup)
1218 ld->write_wakeup(tty);
1219 tty_ldisc_deref(ld);
1222 wake_up_interruptible(&tty->write_wait);
1225 EXPORT_SYMBOL_GPL(tty_wakeup);
1228 * tty_ldisc_flush - flush line discipline queue
1231 * Flush the line discipline queue (if any) for this tty. If there
1232 * is no line discipline active this is a no-op.
1235 void tty_ldisc_flush(struct tty_struct *tty)
1237 struct tty_ldisc *ld = tty_ldisc_ref(tty);
1239 if(ld->flush_buffer)
1240 ld->flush_buffer(tty);
1241 tty_ldisc_deref(ld);
1245 EXPORT_SYMBOL_GPL(tty_ldisc_flush);
1248 * tty_reset_termios - reset terminal state
1249 * @tty: tty to reset
1251 * Restore a terminal to the driver default state
1254 static void tty_reset_termios(struct tty_struct *tty)
1256 mutex_lock(&tty->termios_mutex);
1257 *tty->termios = tty->driver->init_termios;
1258 tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
1259 tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
1260 mutex_unlock(&tty->termios_mutex);
1264 * do_tty_hangup - actual handler for hangup events
1267 * This can be called by the "eventd" kernel thread. That is process
1268 * synchronous but doesn't hold any locks, so we need to make sure we
1269 * have the appropriate locks for what we're doing.
1271 * The hangup event clears any pending redirections onto the hung up
1272 * device. It ensures future writes will error and it does the needed
1273 * line discipline hangup and signal delivery. The tty object itself
1278 * redirect lock for undoing redirection
1279 * file list lock for manipulating list of ttys
1280 * tty_ldisc_lock from called functions
1281 * termios_mutex resetting termios data
1282 * tasklist_lock to walk task list for hangup event
1283 * ->siglock to protect ->signal/->sighand
1285 static void do_tty_hangup(struct work_struct *work)
1287 struct tty_struct *tty =
1288 container_of(work, struct tty_struct, hangup_work);
1289 struct file * cons_filp = NULL;
1290 struct file *filp, *f = NULL;
1291 struct task_struct *p;
1292 struct tty_ldisc *ld;
1293 int closecount = 0, n;
1298 /* inuse_filps is protected by the single kernel lock */
1301 spin_lock(&redirect_lock);
1302 if (redirect && redirect->private_data == tty) {
1306 spin_unlock(&redirect_lock);
1308 check_tty_count(tty, "do_tty_hangup");
1310 /* This breaks for file handles being sent over AF_UNIX sockets ? */
1311 list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) {
1312 if (filp->f_op->write == redirected_tty_write)
1314 if (filp->f_op->write != tty_write)
1317 tty_fasync(-1, filp, 0); /* can't block */
1318 filp->f_op = &hung_up_tty_fops;
1322 /* FIXME! What are the locking issues here? This may me overdoing things..
1323 * this question is especially important now that we've removed the irqlock. */
1325 ld = tty_ldisc_ref(tty);
1326 if(ld != NULL) /* We may have no line discipline at this point */
1328 if (ld->flush_buffer)
1329 ld->flush_buffer(tty);
1330 if (tty->driver->flush_buffer)
1331 tty->driver->flush_buffer(tty);
1332 if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) &&
1334 ld->write_wakeup(tty);
1339 /* FIXME: Once we trust the LDISC code better we can wait here for
1340 ldisc completion and fix the driver call race */
1342 wake_up_interruptible(&tty->write_wait);
1343 wake_up_interruptible(&tty->read_wait);
1346 * Shutdown the current line discipline, and reset it to
1349 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1350 tty_reset_termios(tty);
1352 /* Defer ldisc switch */
1353 /* tty_deferred_ldisc_switch(N_TTY);
1355 This should get done automatically when the port closes and
1356 tty_release is called */
1358 read_lock(&tasklist_lock);
1360 do_each_pid_task(tty->session, PIDTYPE_SID, p) {
1361 spin_lock_irq(&p->sighand->siglock);
1362 if (p->signal->tty == tty)
1363 p->signal->tty = NULL;
1364 if (!p->signal->leader) {
1365 spin_unlock_irq(&p->sighand->siglock);
1368 __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
1369 __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
1370 put_pid(p->signal->tty_old_pgrp); /* A noop */
1372 p->signal->tty_old_pgrp = get_pid(tty->pgrp);
1373 spin_unlock_irq(&p->sighand->siglock);
1374 } while_each_pid_task(tty->session, PIDTYPE_SID, p);
1376 read_unlock(&tasklist_lock);
1379 tty->session = NULL;
1381 tty->ctrl_status = 0;
1383 * If one of the devices matches a console pointer, we
1384 * cannot just call hangup() because that will cause
1385 * tty->count and state->count to go out of sync.
1386 * So we just call close() the right number of times.
1389 if (tty->driver->close)
1390 for (n = 0; n < closecount; n++)
1391 tty->driver->close(tty, cons_filp);
1392 } else if (tty->driver->hangup)
1393 (tty->driver->hangup)(tty);
1395 /* We don't want to have driver/ldisc interactions beyond
1396 the ones we did here. The driver layer expects no
1397 calls after ->hangup() from the ldisc side. However we
1398 can't yet guarantee all that */
1400 set_bit(TTY_HUPPED, &tty->flags);
1402 tty_ldisc_enable(tty);
1403 tty_ldisc_deref(ld);
1411 * tty_hangup - trigger a hangup event
1412 * @tty: tty to hangup
1414 * A carrier loss (virtual or otherwise) has occurred on this like
1415 * schedule a hangup sequence to run after this event.
1418 void tty_hangup(struct tty_struct * tty)
1420 #ifdef TTY_DEBUG_HANGUP
1423 printk(KERN_DEBUG "%s hangup...\n", tty_name(tty, buf));
1425 schedule_work(&tty->hangup_work);
1428 EXPORT_SYMBOL(tty_hangup);
1431 * tty_vhangup - process vhangup
1432 * @tty: tty to hangup
1434 * The user has asked via system call for the terminal to be hung up.
1435 * We do this synchronously so that when the syscall returns the process
1436 * is complete. That guarantee is neccessary for security reasons.
1439 void tty_vhangup(struct tty_struct * tty)
1441 #ifdef TTY_DEBUG_HANGUP
1444 printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf));
1446 do_tty_hangup(&tty->hangup_work);
1448 EXPORT_SYMBOL(tty_vhangup);
1451 * tty_hung_up_p - was tty hung up
1452 * @filp: file pointer of tty
1454 * Return true if the tty has been subject to a vhangup or a carrier
1458 int tty_hung_up_p(struct file * filp)
1460 return (filp->f_op == &hung_up_tty_fops);
1463 EXPORT_SYMBOL(tty_hung_up_p);
1465 static void session_clear_tty(struct pid *session)
1467 struct task_struct *p;
1468 do_each_pid_task(session, PIDTYPE_SID, p) {
1470 } while_each_pid_task(session, PIDTYPE_SID, p);
1474 * disassociate_ctty - disconnect controlling tty
1475 * @on_exit: true if exiting so need to "hang up" the session
1477 * This function is typically called only by the session leader, when
1478 * it wants to disassociate itself from its controlling tty.
1480 * It performs the following functions:
1481 * (1) Sends a SIGHUP and SIGCONT to the foreground process group
1482 * (2) Clears the tty from being controlling the session
1483 * (3) Clears the controlling tty for all processes in the
1486 * The argument on_exit is set to 1 if called when a process is
1487 * exiting; it is 0 if called by the ioctl TIOCNOTTY.
1490 * BKL is taken for hysterical raisins
1491 * tty_mutex is taken to protect tty
1492 * ->siglock is taken to protect ->signal/->sighand
1493 * tasklist_lock is taken to walk process list for sessions
1494 * ->siglock is taken to protect ->signal/->sighand
1497 void disassociate_ctty(int on_exit)
1499 struct tty_struct *tty;
1500 struct pid *tty_pgrp = NULL;
1504 mutex_lock(&tty_mutex);
1505 tty = get_current_tty();
1507 tty_pgrp = get_pid(tty->pgrp);
1508 mutex_unlock(&tty_mutex);
1509 /* XXX: here we race, there is nothing protecting tty */
1510 if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)
1512 } else if (on_exit) {
1513 struct pid *old_pgrp;
1514 spin_lock_irq(¤t->sighand->siglock);
1515 old_pgrp = current->signal->tty_old_pgrp;
1516 current->signal->tty_old_pgrp = NULL;
1517 spin_unlock_irq(¤t->sighand->siglock);
1519 kill_pgrp(old_pgrp, SIGHUP, on_exit);
1520 kill_pgrp(old_pgrp, SIGCONT, on_exit);
1523 mutex_unlock(&tty_mutex);
1528 kill_pgrp(tty_pgrp, SIGHUP, on_exit);
1530 kill_pgrp(tty_pgrp, SIGCONT, on_exit);
1534 spin_lock_irq(¤t->sighand->siglock);
1535 tty_pgrp = current->signal->tty_old_pgrp;
1536 current->signal->tty_old_pgrp = NULL;
1537 spin_unlock_irq(¤t->sighand->siglock);
1540 mutex_lock(&tty_mutex);
1541 /* It is possible that do_tty_hangup has free'd this tty */
1542 tty = get_current_tty();
1544 put_pid(tty->session);
1546 tty->session = NULL;
1549 #ifdef TTY_DEBUG_HANGUP
1550 printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
1554 mutex_unlock(&tty_mutex);
1556 /* Now clear signal->tty under the lock */
1557 read_lock(&tasklist_lock);
1558 session_clear_tty(task_session(current));
1559 read_unlock(&tasklist_lock);
1565 * stop_tty - propogate flow control
1568 * Perform flow control to the driver. For PTY/TTY pairs we
1569 * must also propogate the TIOCKPKT status. May be called
1570 * on an already stopped device and will not re-call the driver
1573 * This functionality is used by both the line disciplines for
1574 * halting incoming flow and by the driver. It may therefore be
1575 * called from any context, may be under the tty atomic_write_lock
1579 * Broken. Relies on BKL which is unsafe here.
1582 void stop_tty(struct tty_struct *tty)
1587 if (tty->link && tty->link->packet) {
1588 tty->ctrl_status &= ~TIOCPKT_START;
1589 tty->ctrl_status |= TIOCPKT_STOP;
1590 wake_up_interruptible(&tty->link->read_wait);
1592 if (tty->driver->stop)
1593 (tty->driver->stop)(tty);
1596 EXPORT_SYMBOL(stop_tty);
1599 * start_tty - propogate flow control
1600 * @tty: tty to start
1602 * Start a tty that has been stopped if at all possible. Perform
1603 * any neccessary wakeups and propogate the TIOCPKT status. If this
1604 * is the tty was previous stopped and is being started then the
1605 * driver start method is invoked and the line discipline woken.
1608 * Broken. Relies on BKL which is unsafe here.
1611 void start_tty(struct tty_struct *tty)
1613 if (!tty->stopped || tty->flow_stopped)
1616 if (tty->link && tty->link->packet) {
1617 tty->ctrl_status &= ~TIOCPKT_STOP;
1618 tty->ctrl_status |= TIOCPKT_START;
1619 wake_up_interruptible(&tty->link->read_wait);
1621 if (tty->driver->start)
1622 (tty->driver->start)(tty);
1624 /* If we have a running line discipline it may need kicking */
1628 EXPORT_SYMBOL(start_tty);
1631 * tty_read - read method for tty device files
1632 * @file: pointer to tty file
1634 * @count: size of user buffer
1637 * Perform the read system call function on this terminal device. Checks
1638 * for hung up devices before calling the line discipline method.
1641 * Locks the line discipline internally while needed
1642 * For historical reasons the line discipline read method is
1643 * invoked under the BKL. This will go away in time so do not rely on it
1644 * in new code. Multiple read calls may be outstanding in parallel.
1647 static ssize_t tty_read(struct file * file, char __user * buf, size_t count,
1651 struct tty_struct * tty;
1652 struct inode *inode;
1653 struct tty_ldisc *ld;
1655 tty = (struct tty_struct *)file->private_data;
1656 inode = file->f_path.dentry->d_inode;
1657 if (tty_paranoia_check(tty, inode, "tty_read"))
1659 if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags)))
1662 /* We want to wait for the line discipline to sort out in this
1664 ld = tty_ldisc_ref_wait(tty);
1667 i = (ld->read)(tty,file,buf,count);
1670 tty_ldisc_deref(ld);
1673 inode->i_atime = current_fs_time(inode->i_sb);
1678 * Split writes up in sane blocksizes to avoid
1679 * denial-of-service type attacks
1681 static inline ssize_t do_tty_write(
1682 ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
1683 struct tty_struct *tty,
1685 const char __user *buf,
1688 ssize_t ret = 0, written = 0;
1691 /* FIXME: O_NDELAY ... */
1692 if (mutex_lock_interruptible(&tty->atomic_write_lock)) {
1693 return -ERESTARTSYS;
1697 * We chunk up writes into a temporary buffer. This
1698 * simplifies low-level drivers immensely, since they
1699 * don't have locking issues and user mode accesses.
1701 * But if TTY_NO_WRITE_SPLIT is set, we should use a
1704 * The default chunk-size is 2kB, because the NTTY
1705 * layer has problems with bigger chunks. It will
1706 * claim to be able to handle more characters than
1709 * FIXME: This can probably go away now except that 64K chunks
1710 * are too likely to fail unless switched to vmalloc...
1713 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
1718 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
1719 if (tty->write_cnt < chunk) {
1725 buf = kmalloc(chunk, GFP_KERNEL);
1727 mutex_unlock(&tty->atomic_write_lock);
1730 kfree(tty->write_buf);
1731 tty->write_cnt = chunk;
1732 tty->write_buf = buf;
1735 /* Do the write .. */
1737 size_t size = count;
1741 if (copy_from_user(tty->write_buf, buf, size))
1744 ret = write(tty, file, tty->write_buf, size);
1754 if (signal_pending(current))
1759 struct inode *inode = file->f_path.dentry->d_inode;
1760 inode->i_mtime = current_fs_time(inode->i_sb);
1763 mutex_unlock(&tty->atomic_write_lock);
1769 * tty_write - write method for tty device file
1770 * @file: tty file pointer
1771 * @buf: user data to write
1772 * @count: bytes to write
1775 * Write data to a tty device via the line discipline.
1778 * Locks the line discipline as required
1779 * Writes to the tty driver are serialized by the atomic_write_lock
1780 * and are then processed in chunks to the device. The line discipline
1781 * write method will not be involked in parallel for each device
1782 * The line discipline write method is called under the big
1783 * kernel lock for historical reasons. New code should not rely on this.
1786 static ssize_t tty_write(struct file * file, const char __user * buf, size_t count,
1789 struct tty_struct * tty;
1790 struct inode *inode = file->f_path.dentry->d_inode;
1792 struct tty_ldisc *ld;
1794 tty = (struct tty_struct *)file->private_data;
1795 if (tty_paranoia_check(tty, inode, "tty_write"))
1797 if (!tty || !tty->driver->write || (test_bit(TTY_IO_ERROR, &tty->flags)))
1800 ld = tty_ldisc_ref_wait(tty);
1804 ret = do_tty_write(ld->write, tty, file, buf, count);
1805 tty_ldisc_deref(ld);
1809 ssize_t redirected_tty_write(struct file * file, const char __user * buf, size_t count,
1812 struct file *p = NULL;
1814 spin_lock(&redirect_lock);
1819 spin_unlock(&redirect_lock);
1823 res = vfs_write(p, buf, count, &p->f_pos);
1828 return tty_write(file, buf, count, ppos);
1831 static char ptychar[] = "pqrstuvwxyzabcde";
1834 * pty_line_name - generate name for a pty
1835 * @driver: the tty driver in use
1836 * @index: the minor number
1837 * @p: output buffer of at least 6 bytes
1839 * Generate a name from a driver reference and write it to the output
1844 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1846 int i = index + driver->name_base;
1847 /* ->name is initialized to "ttyp", but "tty" is expected */
1848 sprintf(p, "%s%c%x",
1849 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1850 ptychar[i >> 4 & 0xf], i & 0xf);
1854 * pty_line_name - generate name for a tty
1855 * @driver: the tty driver in use
1856 * @index: the minor number
1857 * @p: output buffer of at least 7 bytes
1859 * Generate a name from a driver reference and write it to the output
1864 static void tty_line_name(struct tty_driver *driver, int index, char *p)
1866 sprintf(p, "%s%d", driver->name, index + driver->name_base);
1870 * init_dev - initialise a tty device
1871 * @driver: tty driver we are opening a device on
1872 * @idx: device index
1873 * @tty: returned tty structure
1875 * Prepare a tty device. This may not be a "new" clean device but
1876 * could also be an active device. The pty drivers require special
1877 * handling because of this.
1880 * The function is called under the tty_mutex, which
1881 * protects us from the tty struct or driver itself going away.
1883 * On exit the tty device has the line discipline attached and
1884 * a reference count of 1. If a pair was created for pty/tty use
1885 * and the other was a pty master then it too has a reference count of 1.
1887 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1888 * failed open. The new code protects the open with a mutex, so it's
1889 * really quite straightforward. The mutex locking can probably be
1890 * relaxed for the (most common) case of reopening a tty.
1893 static int init_dev(struct tty_driver *driver, int idx,
1894 struct tty_struct **ret_tty)
1896 struct tty_struct *tty, *o_tty;
1897 struct ktermios *tp, **tp_loc, *o_tp, **o_tp_loc;
1898 struct ktermios *ltp, **ltp_loc, *o_ltp, **o_ltp_loc;
1901 /* check whether we're reopening an existing tty */
1902 if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
1903 tty = devpts_get_tty(idx);
1904 if (tty && driver->subtype == PTY_TYPE_MASTER)
1907 tty = driver->ttys[idx];
1909 if (tty) goto fast_track;
1912 * First time open is complex, especially for PTY devices.
1913 * This code guarantees that either everything succeeds and the
1914 * TTY is ready for operation, or else the table slots are vacated
1915 * and the allocated memory released. (Except that the termios
1916 * and locked termios may be retained.)
1919 if (!try_module_get(driver->owner)) {
1928 tty = alloc_tty_struct();
1931 initialize_tty_struct(tty);
1932 tty->driver = driver;
1934 tty_line_name(driver, idx, tty->name);
1936 if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
1937 tp_loc = &tty->termios;
1938 ltp_loc = &tty->termios_locked;
1940 tp_loc = &driver->termios[idx];
1941 ltp_loc = &driver->termios_locked[idx];
1945 tp = (struct ktermios *) kmalloc(sizeof(struct ktermios),
1949 *tp = driver->init_termios;
1953 ltp = (struct ktermios *) kmalloc(sizeof(struct ktermios),
1957 memset(ltp, 0, sizeof(struct ktermios));
1960 if (driver->type == TTY_DRIVER_TYPE_PTY) {
1961 o_tty = alloc_tty_struct();
1964 initialize_tty_struct(o_tty);
1965 o_tty->driver = driver->other;
1967 tty_line_name(driver->other, idx, o_tty->name);
1969 if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
1970 o_tp_loc = &o_tty->termios;
1971 o_ltp_loc = &o_tty->termios_locked;
1973 o_tp_loc = &driver->other->termios[idx];
1974 o_ltp_loc = &driver->other->termios_locked[idx];
1978 o_tp = (struct ktermios *)
1979 kmalloc(sizeof(struct ktermios), GFP_KERNEL);
1982 *o_tp = driver->other->init_termios;
1986 o_ltp = (struct ktermios *)
1987 kmalloc(sizeof(struct ktermios), GFP_KERNEL);
1990 memset(o_ltp, 0, sizeof(struct ktermios));
1994 * Everything allocated ... set up the o_tty structure.
1996 if (!(driver->other->flags & TTY_DRIVER_DEVPTS_MEM)) {
1997 driver->other->ttys[idx] = o_tty;
2003 o_tty->termios = *o_tp_loc;
2004 o_tty->termios_locked = *o_ltp_loc;
2005 driver->other->refcount++;
2006 if (driver->subtype == PTY_TYPE_MASTER)
2009 /* Establish the links in both directions */
2015 * All structures have been allocated, so now we install them.
2016 * Failures after this point use release_tty to clean up, so
2017 * there's no need to null out the local pointers.
2019 if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
2020 driver->ttys[idx] = tty;
2027 tty->termios = *tp_loc;
2028 tty->termios_locked = *ltp_loc;
2029 /* Compatibility until drivers always set this */
2030 tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
2031 tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
2036 * Structures all installed ... call the ldisc open routines.
2037 * If we fail here just call release_tty to clean up. No need
2038 * to decrement the use counts, as release_tty doesn't care.
2041 if (tty->ldisc.open) {
2042 retval = (tty->ldisc.open)(tty);
2044 goto release_mem_out;
2046 if (o_tty && o_tty->ldisc.open) {
2047 retval = (o_tty->ldisc.open)(o_tty);
2049 if (tty->ldisc.close)
2050 (tty->ldisc.close)(tty);
2051 goto release_mem_out;
2053 tty_ldisc_enable(o_tty);
2055 tty_ldisc_enable(tty);
2059 * This fast open can be used if the tty is already open.
2060 * No memory is allocated, and the only failures are from
2061 * attempting to open a closing tty or attempting multiple
2062 * opens on a pty master.
2065 if (test_bit(TTY_CLOSING, &tty->flags)) {
2069 if (driver->type == TTY_DRIVER_TYPE_PTY &&
2070 driver->subtype == PTY_TYPE_MASTER) {
2072 * special case for PTY masters: only one open permitted,
2073 * and the slave side open count is incremented as well.
2082 tty->driver = driver; /* N.B. why do this every time?? */
2085 if(!test_bit(TTY_LDISC, &tty->flags))
2086 printk(KERN_ERR "init_dev but no ldisc\n");
2090 /* All paths come through here to release the mutex */
2094 /* Release locally allocated memory ... nothing placed in slots */
2098 free_tty_struct(o_tty);
2101 free_tty_struct(tty);
2104 module_put(driver->owner);
2108 /* call the tty release_tty routine to clean out this slot */
2110 if (printk_ratelimit())
2111 printk(KERN_INFO "init_dev: ldisc open failed, "
2112 "clearing slot %d\n", idx);
2113 release_tty(tty, idx);
2118 * release_one_tty - release tty structure memory
2120 * Releases memory associated with a tty structure, and clears out the
2121 * driver table slots. This function is called when a device is no longer
2122 * in use. It also gets called when setup of a device fails.
2125 * tty_mutex - sometimes only
2126 * takes the file list lock internally when working on the list
2127 * of ttys that the driver keeps.
2128 * FIXME: should we require tty_mutex is held here ??
2130 static void release_one_tty(struct tty_struct *tty, int idx)
2132 int devpts = tty->driver->flags & TTY_DRIVER_DEVPTS_MEM;
2133 struct ktermios *tp;
2136 tty->driver->ttys[idx] = NULL;
2138 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
2141 tty->driver->termios[idx] = NULL;
2144 tp = tty->termios_locked;
2146 tty->driver->termios_locked[idx] = NULL;
2152 tty->driver->refcount--;
2155 list_del_init(&tty->tty_files);
2158 free_tty_struct(tty);
2162 * release_tty - release tty structure memory
2164 * Release both @tty and a possible linked partner (think pty pair),
2165 * and decrement the refcount of the backing module.
2168 * tty_mutex - sometimes only
2169 * takes the file list lock internally when working on the list
2170 * of ttys that the driver keeps.
2171 * FIXME: should we require tty_mutex is held here ??
2173 static void release_tty(struct tty_struct *tty, int idx)
2175 struct tty_driver *driver = tty->driver;
2178 release_one_tty(tty->link, idx);
2179 release_one_tty(tty, idx);
2180 module_put(driver->owner);
2184 * Even releasing the tty structures is a tricky business.. We have
2185 * to be very careful that the structures are all released at the
2186 * same time, as interrupts might otherwise get the wrong pointers.
2188 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
2189 * lead to double frees or releasing memory still in use.
2191 static void release_dev(struct file * filp)
2193 struct tty_struct *tty, *o_tty;
2194 int pty_master, tty_closing, o_tty_closing, do_sleep;
2198 unsigned long flags;
2200 tty = (struct tty_struct *)filp->private_data;
2201 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "release_dev"))
2204 check_tty_count(tty, "release_dev");
2206 tty_fasync(-1, filp, 0);
2209 pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2210 tty->driver->subtype == PTY_TYPE_MASTER);
2211 devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0;
2214 #ifdef TTY_PARANOIA_CHECK
2215 if (idx < 0 || idx >= tty->driver->num) {
2216 printk(KERN_DEBUG "release_dev: bad idx when trying to "
2217 "free (%s)\n", tty->name);
2220 if (!(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
2221 if (tty != tty->driver->ttys[idx]) {
2222 printk(KERN_DEBUG "release_dev: driver.table[%d] not tty "
2223 "for (%s)\n", idx, tty->name);
2226 if (tty->termios != tty->driver->termios[idx]) {
2227 printk(KERN_DEBUG "release_dev: driver.termios[%d] not termios "
2232 if (tty->termios_locked != tty->driver->termios_locked[idx]) {
2233 printk(KERN_DEBUG "release_dev: driver.termios_locked[%d] not "
2234 "termios_locked for (%s)\n",
2241 #ifdef TTY_DEBUG_HANGUP
2242 printk(KERN_DEBUG "release_dev of %s (tty count=%d)...",
2243 tty_name(tty, buf), tty->count);
2246 #ifdef TTY_PARANOIA_CHECK
2247 if (tty->driver->other &&
2248 !(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
2249 if (o_tty != tty->driver->other->ttys[idx]) {
2250 printk(KERN_DEBUG "release_dev: other->table[%d] "
2251 "not o_tty for (%s)\n",
2255 if (o_tty->termios != tty->driver->other->termios[idx]) {
2256 printk(KERN_DEBUG "release_dev: other->termios[%d] "
2257 "not o_termios for (%s)\n",
2261 if (o_tty->termios_locked !=
2262 tty->driver->other->termios_locked[idx]) {
2263 printk(KERN_DEBUG "release_dev: other->termios_locked["
2264 "%d] not o_termios_locked for (%s)\n",
2268 if (o_tty->link != tty) {
2269 printk(KERN_DEBUG "release_dev: bad pty pointers\n");
2274 if (tty->driver->close)
2275 tty->driver->close(tty, filp);
2278 * Sanity check: if tty->count is going to zero, there shouldn't be
2279 * any waiters on tty->read_wait or tty->write_wait. We test the
2280 * wait queues and kick everyone out _before_ actually starting to
2281 * close. This ensures that we won't block while releasing the tty
2284 * The test for the o_tty closing is necessary, since the master and
2285 * slave sides may close in any order. If the slave side closes out
2286 * first, its count will be one, since the master side holds an open.
2287 * Thus this test wouldn't be triggered at the time the slave closes,
2290 * Note that it's possible for the tty to be opened again while we're
2291 * flushing out waiters. By recalculating the closing flags before
2292 * each iteration we avoid any problems.
2295 /* Guard against races with tty->count changes elsewhere and
2296 opens on /dev/tty */
2298 mutex_lock(&tty_mutex);
2299 tty_closing = tty->count <= 1;
2300 o_tty_closing = o_tty &&
2301 (o_tty->count <= (pty_master ? 1 : 0));
2305 if (waitqueue_active(&tty->read_wait)) {
2306 wake_up(&tty->read_wait);
2309 if (waitqueue_active(&tty->write_wait)) {
2310 wake_up(&tty->write_wait);
2314 if (o_tty_closing) {
2315 if (waitqueue_active(&o_tty->read_wait)) {
2316 wake_up(&o_tty->read_wait);
2319 if (waitqueue_active(&o_tty->write_wait)) {
2320 wake_up(&o_tty->write_wait);
2327 printk(KERN_WARNING "release_dev: %s: read/write wait queue "
2328 "active!\n", tty_name(tty, buf));
2329 mutex_unlock(&tty_mutex);
2334 * The closing flags are now consistent with the open counts on
2335 * both sides, and we've completed the last operation that could
2336 * block, so it's safe to proceed with closing.
2339 if (--o_tty->count < 0) {
2340 printk(KERN_WARNING "release_dev: bad pty slave count "
2342 o_tty->count, tty_name(o_tty, buf));
2346 if (--tty->count < 0) {
2347 printk(KERN_WARNING "release_dev: bad tty->count (%d) for %s\n",
2348 tty->count, tty_name(tty, buf));
2353 * We've decremented tty->count, so we need to remove this file
2354 * descriptor off the tty->tty_files list; this serves two
2356 * - check_tty_count sees the correct number of file descriptors
2357 * associated with this tty.
2358 * - do_tty_hangup no longer sees this file descriptor as
2359 * something that needs to be handled for hangups.
2362 filp->private_data = NULL;
2365 * Perform some housekeeping before deciding whether to return.
2367 * Set the TTY_CLOSING flag if this was the last open. In the
2368 * case of a pty we may have to wait around for the other side
2369 * to close, and TTY_CLOSING makes sure we can't be reopened.
2372 set_bit(TTY_CLOSING, &tty->flags);
2374 set_bit(TTY_CLOSING, &o_tty->flags);
2377 * If _either_ side is closing, make sure there aren't any
2378 * processes that still think tty or o_tty is their controlling
2381 if (tty_closing || o_tty_closing) {
2382 read_lock(&tasklist_lock);
2383 session_clear_tty(tty->session);
2385 session_clear_tty(o_tty->session);
2386 read_unlock(&tasklist_lock);
2389 mutex_unlock(&tty_mutex);
2391 /* check whether both sides are closing ... */
2392 if (!tty_closing || (o_tty && !o_tty_closing))
2395 #ifdef TTY_DEBUG_HANGUP
2396 printk(KERN_DEBUG "freeing tty structure...");
2399 * Prevent flush_to_ldisc() from rescheduling the work for later. Then
2400 * kill any delayed work. As this is the final close it does not
2401 * race with the set_ldisc code path.
2403 clear_bit(TTY_LDISC, &tty->flags);
2404 cancel_delayed_work(&tty->buf.work);
2407 * Wait for ->hangup_work and ->buf.work handlers to terminate
2410 flush_scheduled_work();
2413 * Wait for any short term users (we know they are just driver
2414 * side waiters as the file is closing so user count on the file
2417 spin_lock_irqsave(&tty_ldisc_lock, flags);
2418 while(tty->ldisc.refcount)
2420 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
2421 wait_event(tty_ldisc_wait, tty->ldisc.refcount == 0);
2422 spin_lock_irqsave(&tty_ldisc_lock, flags);
2424 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
2426 * Shutdown the current line discipline, and reset it to N_TTY.
2427 * N.B. why reset ldisc when we're releasing the memory??
2429 * FIXME: this MUST get fixed for the new reflocking
2431 if (tty->ldisc.close)
2432 (tty->ldisc.close)(tty);
2433 tty_ldisc_put(tty->ldisc.num);
2436 * Switch the line discipline back
2438 tty_ldisc_assign(tty, tty_ldisc_get(N_TTY));
2439 tty_set_termios_ldisc(tty,N_TTY);
2441 /* FIXME: could o_tty be in setldisc here ? */
2442 clear_bit(TTY_LDISC, &o_tty->flags);
2443 if (o_tty->ldisc.close)
2444 (o_tty->ldisc.close)(o_tty);
2445 tty_ldisc_put(o_tty->ldisc.num);
2446 tty_ldisc_assign(o_tty, tty_ldisc_get(N_TTY));
2447 tty_set_termios_ldisc(o_tty,N_TTY);
2450 * The release_tty function takes care of the details of clearing
2451 * the slots and preserving the termios structure.
2453 release_tty(tty, idx);
2455 #ifdef CONFIG_UNIX98_PTYS
2456 /* Make this pty number available for reallocation */
2458 down(&allocated_ptys_lock);
2459 idr_remove(&allocated_ptys, idx);
2460 up(&allocated_ptys_lock);
2467 * tty_open - open a tty device
2468 * @inode: inode of device file
2469 * @filp: file pointer to tty
2471 * tty_open and tty_release keep up the tty count that contains the
2472 * number of opens done on a tty. We cannot use the inode-count, as
2473 * different inodes might point to the same tty.
2475 * Open-counting is needed for pty masters, as well as for keeping
2476 * track of serial lines: DTR is dropped when the last close happens.
2477 * (This is not done solely through tty->count, now. - Ted 1/27/92)
2479 * The termios state of a pty is reset on first open so that
2480 * settings don't persist across reuse.
2482 * Locking: tty_mutex protects tty, get_tty_driver and init_dev work.
2483 * tty->count should protect the rest.
2484 * ->siglock protects ->signal/->sighand
2487 static int tty_open(struct inode * inode, struct file * filp)
2489 struct tty_struct *tty;
2491 struct tty_driver *driver;
2493 dev_t device = inode->i_rdev;
2494 unsigned short saved_flags = filp->f_flags;
2495 struct pid *old_pgrp;
2497 nonseekable_open(inode, filp);
2500 noctty = filp->f_flags & O_NOCTTY;
2504 mutex_lock(&tty_mutex);
2506 if (device == MKDEV(TTYAUX_MAJOR,0)) {
2507 tty = get_current_tty();
2509 mutex_unlock(&tty_mutex);
2512 driver = tty->driver;
2514 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
2519 if (device == MKDEV(TTY_MAJOR,0)) {
2520 extern struct tty_driver *console_driver;
2521 driver = console_driver;
2527 if (device == MKDEV(TTYAUX_MAJOR,1)) {
2528 driver = console_device(&index);
2530 /* Don't let /dev/console block */
2531 filp->f_flags |= O_NONBLOCK;
2535 mutex_unlock(&tty_mutex);
2539 driver = get_tty_driver(device, &index);
2541 mutex_unlock(&tty_mutex);
2545 retval = init_dev(driver, index, &tty);
2546 mutex_unlock(&tty_mutex);
2550 filp->private_data = tty;
2551 file_move(filp, &tty->tty_files);
2552 check_tty_count(tty, "tty_open");
2553 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2554 tty->driver->subtype == PTY_TYPE_MASTER)
2556 #ifdef TTY_DEBUG_HANGUP
2557 printk(KERN_DEBUG "opening %s...", tty->name);
2560 if (tty->driver->open)
2561 retval = tty->driver->open(tty, filp);
2565 filp->f_flags = saved_flags;
2567 if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
2571 #ifdef TTY_DEBUG_HANGUP
2572 printk(KERN_DEBUG "error %d in opening %s...", retval,
2576 if (retval != -ERESTARTSYS)
2578 if (signal_pending(current))
2582 * Need to reset f_op in case a hangup happened.
2584 if (filp->f_op == &hung_up_tty_fops)
2585 filp->f_op = &tty_fops;
2590 mutex_lock(&tty_mutex);
2591 spin_lock_irq(¤t->sighand->siglock);
2593 current->signal->leader &&
2594 !current->signal->tty &&
2595 tty->session == NULL)
2596 old_pgrp = __proc_set_tty(current, tty);
2597 spin_unlock_irq(¤t->sighand->siglock);
2598 mutex_unlock(&tty_mutex);
2603 #ifdef CONFIG_UNIX98_PTYS
2605 * ptmx_open - open a unix 98 pty master
2606 * @inode: inode of device file
2607 * @filp: file pointer to tty
2609 * Allocate a unix98 pty master device from the ptmx driver.
2611 * Locking: tty_mutex protects theinit_dev work. tty->count should
2613 * allocated_ptys_lock handles the list of free pty numbers
2616 static int ptmx_open(struct inode * inode, struct file * filp)
2618 struct tty_struct *tty;
2623 nonseekable_open(inode, filp);
2625 /* find a device that is not in use. */
2626 down(&allocated_ptys_lock);
2627 if (!idr_pre_get(&allocated_ptys, GFP_KERNEL)) {
2628 up(&allocated_ptys_lock);
2631 idr_ret = idr_get_new(&allocated_ptys, NULL, &index);
2633 up(&allocated_ptys_lock);
2634 if (idr_ret == -EAGAIN)
2638 if (index >= pty_limit) {
2639 idr_remove(&allocated_ptys, index);
2640 up(&allocated_ptys_lock);
2643 up(&allocated_ptys_lock);
2645 mutex_lock(&tty_mutex);
2646 retval = init_dev(ptm_driver, index, &tty);
2647 mutex_unlock(&tty_mutex);
2652 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
2653 filp->private_data = tty;
2654 file_move(filp, &tty->tty_files);
2657 if (devpts_pty_new(tty->link))
2660 check_tty_count(tty, "tty_open");
2661 retval = ptm_driver->open(tty, filp);
2668 down(&allocated_ptys_lock);
2669 idr_remove(&allocated_ptys, index);
2670 up(&allocated_ptys_lock);
2676 * tty_release - vfs callback for close
2677 * @inode: inode of tty
2678 * @filp: file pointer for handle to tty
2680 * Called the last time each file handle is closed that references
2681 * this tty. There may however be several such references.
2684 * Takes bkl. See release_dev
2687 static int tty_release(struct inode * inode, struct file * filp)
2696 * tty_poll - check tty status
2697 * @filp: file being polled
2698 * @wait: poll wait structures to update
2700 * Call the line discipline polling method to obtain the poll
2701 * status of the device.
2703 * Locking: locks called line discipline but ldisc poll method
2704 * may be re-entered freely by other callers.
2707 static unsigned int tty_poll(struct file * filp, poll_table * wait)
2709 struct tty_struct * tty;
2710 struct tty_ldisc *ld;
2713 tty = (struct tty_struct *)filp->private_data;
2714 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_poll"))
2717 ld = tty_ldisc_ref_wait(tty);
2719 ret = (ld->poll)(tty, filp, wait);
2720 tty_ldisc_deref(ld);
2724 static int tty_fasync(int fd, struct file * filp, int on)
2726 struct tty_struct * tty;
2729 tty = (struct tty_struct *)filp->private_data;
2730 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_fasync"))
2733 retval = fasync_helper(fd, filp, on, &tty->fasync);
2740 if (!waitqueue_active(&tty->read_wait))
2741 tty->minimum_to_wake = 1;
2744 type = PIDTYPE_PGID;
2746 pid = task_pid(current);
2749 retval = __f_setown(filp, pid, type, 0);
2753 if (!tty->fasync && !waitqueue_active(&tty->read_wait))
2754 tty->minimum_to_wake = N_TTY_BUF_SIZE;
2760 * tiocsti - fake input character
2761 * @tty: tty to fake input into
2762 * @p: pointer to character
2764 * Fake input to a tty device. Does the neccessary locking and
2767 * FIXME: does not honour flow control ??
2770 * Called functions take tty_ldisc_lock
2771 * current->signal->tty check is safe without locks
2773 * FIXME: may race normal receive processing
2776 static int tiocsti(struct tty_struct *tty, char __user *p)
2779 struct tty_ldisc *ld;
2781 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2783 if (get_user(ch, p))
2785 ld = tty_ldisc_ref_wait(tty);
2786 ld->receive_buf(tty, &ch, &mbz, 1);
2787 tty_ldisc_deref(ld);
2792 * tiocgwinsz - implement window query ioctl
2794 * @arg: user buffer for result
2796 * Copies the kernel idea of the window size into the user buffer.
2798 * Locking: tty->termios_mutex is taken to ensure the winsize data
2802 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user * arg)
2806 mutex_lock(&tty->termios_mutex);
2807 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2808 mutex_unlock(&tty->termios_mutex);
2810 return err ? -EFAULT: 0;
2814 * tiocswinsz - implement window size set ioctl
2816 * @arg: user buffer for result
2818 * Copies the user idea of the window size to the kernel. Traditionally
2819 * this is just advisory information but for the Linux console it
2820 * actually has driver level meaning and triggers a VC resize.
2823 * Called function use the console_sem is used to ensure we do
2824 * not try and resize the console twice at once.
2825 * The tty->termios_mutex is used to ensure we don't double
2826 * resize and get confused. Lock order - tty->termios_mutex before
2830 static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty,
2831 struct winsize __user * arg)
2833 struct winsize tmp_ws;
2835 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2838 mutex_lock(&tty->termios_mutex);
2839 if (!memcmp(&tmp_ws, &tty->winsize, sizeof(*arg)))
2843 if (tty->driver->type == TTY_DRIVER_TYPE_CONSOLE) {
2844 if (vc_lock_resize(tty->driver_data, tmp_ws.ws_col,
2846 mutex_unlock(&tty->termios_mutex);
2852 kill_pgrp(tty->pgrp, SIGWINCH, 1);
2853 if ((real_tty->pgrp != tty->pgrp) && real_tty->pgrp)
2854 kill_pgrp(real_tty->pgrp, SIGWINCH, 1);
2855 tty->winsize = tmp_ws;
2856 real_tty->winsize = tmp_ws;
2858 mutex_unlock(&tty->termios_mutex);
2863 * tioccons - allow admin to move logical console
2864 * @file: the file to become console
2866 * Allow the adminstrator to move the redirected console device
2868 * Locking: uses redirect_lock to guard the redirect information
2871 static int tioccons(struct file *file)
2873 if (!capable(CAP_SYS_ADMIN))
2875 if (file->f_op->write == redirected_tty_write) {
2877 spin_lock(&redirect_lock);
2880 spin_unlock(&redirect_lock);
2885 spin_lock(&redirect_lock);
2887 spin_unlock(&redirect_lock);
2892 spin_unlock(&redirect_lock);
2897 * fionbio - non blocking ioctl
2898 * @file: file to set blocking value
2899 * @p: user parameter
2901 * Historical tty interfaces had a blocking control ioctl before
2902 * the generic functionality existed. This piece of history is preserved
2903 * in the expected tty API of posix OS's.
2905 * Locking: none, the open fle handle ensures it won't go away.
2908 static int fionbio(struct file *file, int __user *p)
2912 if (get_user(nonblock, p))
2916 file->f_flags |= O_NONBLOCK;
2918 file->f_flags &= ~O_NONBLOCK;
2923 * tiocsctty - set controlling tty
2924 * @tty: tty structure
2925 * @arg: user argument
2927 * This ioctl is used to manage job control. It permits a session
2928 * leader to set this tty as the controlling tty for the session.
2931 * Takes tty_mutex() to protect tty instance
2932 * Takes tasklist_lock internally to walk sessions
2933 * Takes ->siglock() when updating signal->tty
2936 static int tiocsctty(struct tty_struct *tty, int arg)
2939 if (current->signal->leader && (task_session(current) == tty->session))
2942 mutex_lock(&tty_mutex);
2944 * The process must be a session leader and
2945 * not have a controlling tty already.
2947 if (!current->signal->leader || current->signal->tty) {
2954 * This tty is already the controlling
2955 * tty for another session group!
2957 if ((arg == 1) && capable(CAP_SYS_ADMIN)) {
2961 read_lock(&tasklist_lock);
2962 session_clear_tty(tty->session);
2963 read_unlock(&tasklist_lock);
2969 proc_set_tty(current, tty);
2971 mutex_unlock(&tty_mutex);
2976 * tiocgpgrp - get process group
2977 * @tty: tty passed by user
2978 * @real_tty: tty side of the tty pased by the user if a pty else the tty
2981 * Obtain the process group of the tty. If there is no process group
2984 * Locking: none. Reference to current->signal->tty is safe.
2987 static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2990 * (tty == real_tty) is a cheap way of
2991 * testing if the tty is NOT a master pty.
2993 if (tty == real_tty && current->signal->tty != real_tty)
2995 return put_user(pid_nr(real_tty->pgrp), p);
2999 * tiocspgrp - attempt to set process group
3000 * @tty: tty passed by user
3001 * @real_tty: tty side device matching tty passed by user
3004 * Set the process group of the tty to the session passed. Only
3005 * permitted where the tty session is our session.
3010 static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
3014 int retval = tty_check_change(real_tty);
3020 if (!current->signal->tty ||
3021 (current->signal->tty != real_tty) ||
3022 (real_tty->session != task_session(current)))
3024 if (get_user(pgrp_nr, p))
3029 pgrp = find_pid(pgrp_nr);
3034 if (session_of_pgrp(pgrp) != task_session(current))
3037 put_pid(real_tty->pgrp);
3038 real_tty->pgrp = get_pid(pgrp);
3045 * tiocgsid - get session id
3046 * @tty: tty passed by user
3047 * @real_tty: tty side of the tty pased by the user if a pty else the tty
3048 * @p: pointer to returned session id
3050 * Obtain the session id of the tty. If there is no session
3053 * Locking: none. Reference to current->signal->tty is safe.
3056 static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
3059 * (tty == real_tty) is a cheap way of
3060 * testing if the tty is NOT a master pty.
3062 if (tty == real_tty && current->signal->tty != real_tty)
3064 if (!real_tty->session)
3066 return put_user(pid_nr(real_tty->session), p);
3070 * tiocsetd - set line discipline
3072 * @p: pointer to user data
3074 * Set the line discipline according to user request.
3076 * Locking: see tty_set_ldisc, this function is just a helper
3079 static int tiocsetd(struct tty_struct *tty, int __user *p)
3083 if (get_user(ldisc, p))
3085 return tty_set_ldisc(tty, ldisc);
3089 * send_break - performed time break
3090 * @tty: device to break on
3091 * @duration: timeout in mS
3093 * Perform a timed break on hardware that lacks its own driver level
3094 * timed break functionality.
3097 * atomic_write_lock serializes
3101 static int send_break(struct tty_struct *tty, unsigned int duration)
3103 if (mutex_lock_interruptible(&tty->atomic_write_lock))
3105 tty->driver->break_ctl(tty, -1);
3106 if (!signal_pending(current)) {
3107 msleep_interruptible(duration);
3109 tty->driver->break_ctl(tty, 0);
3110 mutex_unlock(&tty->atomic_write_lock);
3111 if (signal_pending(current))
3117 * tiocmget - get modem status
3119 * @file: user file pointer
3120 * @p: pointer to result
3122 * Obtain the modem status bits from the tty driver if the feature
3123 * is supported. Return -EINVAL if it is not available.
3125 * Locking: none (up to the driver)
3128 static int tty_tiocmget(struct tty_struct *tty, struct file *file, int __user *p)
3130 int retval = -EINVAL;
3132 if (tty->driver->tiocmget) {
3133 retval = tty->driver->tiocmget(tty, file);
3136 retval = put_user(retval, p);
3142 * tiocmset - set modem status
3144 * @file: user file pointer
3145 * @cmd: command - clear bits, set bits or set all
3146 * @p: pointer to desired bits
3148 * Set the modem status bits from the tty driver if the feature
3149 * is supported. Return -EINVAL if it is not available.
3151 * Locking: none (up to the driver)
3154 static int tty_tiocmset(struct tty_struct *tty, struct file *file, unsigned int cmd,
3157 int retval = -EINVAL;
3159 if (tty->driver->tiocmset) {
3160 unsigned int set, clear, val;
3162 retval = get_user(val, p);
3180 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
3181 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
3183 retval = tty->driver->tiocmset(tty, file, set, clear);
3189 * Split this up, as gcc can choke on it otherwise..
3191 int tty_ioctl(struct inode * inode, struct file * file,
3192 unsigned int cmd, unsigned long arg)
3194 struct tty_struct *tty, *real_tty;
3195 void __user *p = (void __user *)arg;
3197 struct tty_ldisc *ld;
3199 tty = (struct tty_struct *)file->private_data;
3200 if (tty_paranoia_check(tty, inode, "tty_ioctl"))
3203 /* CHECKME: is this safe as one end closes ? */
3206 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
3207 tty->driver->subtype == PTY_TYPE_MASTER)
3208 real_tty = tty->link;
3211 * Break handling by driver
3213 if (!tty->driver->break_ctl) {
3217 if (tty->driver->ioctl)
3218 return tty->driver->ioctl(tty, file, cmd, arg);
3221 /* These two ioctl's always return success; even if */
3222 /* the driver doesn't support them. */
3225 if (!tty->driver->ioctl)
3227 retval = tty->driver->ioctl(tty, file, cmd, arg);
3228 if (retval == -ENOIOCTLCMD)
3235 * Factor out some common prep work
3243 retval = tty_check_change(tty);
3246 if (cmd != TIOCCBRK) {
3247 tty_wait_until_sent(tty, 0);
3248 if (signal_pending(current))
3256 return tiocsti(tty, p);
3258 return tiocgwinsz(tty, p);
3260 return tiocswinsz(tty, real_tty, p);
3262 return real_tty!=tty ? -EINVAL : tioccons(file);
3264 return fionbio(file, p);
3266 set_bit(TTY_EXCLUSIVE, &tty->flags);
3269 clear_bit(TTY_EXCLUSIVE, &tty->flags);
3272 if (current->signal->tty != tty)
3274 if (current->signal->leader)
3275 disassociate_ctty(0);
3276 proc_clear_tty(current);
3279 return tiocsctty(tty, arg);
3281 return tiocgpgrp(tty, real_tty, p);
3283 return tiocspgrp(tty, real_tty, p);
3285 return tiocgsid(tty, real_tty, p);
3287 /* FIXME: check this is ok */
3288 return put_user(tty->ldisc.num, (int __user *)p);
3290 return tiocsetd(tty, p);
3293 return tioclinux(tty, arg);
3298 case TIOCSBRK: /* Turn break on, unconditionally */
3299 tty->driver->break_ctl(tty, -1);
3302 case TIOCCBRK: /* Turn break off, unconditionally */
3303 tty->driver->break_ctl(tty, 0);
3305 case TCSBRK: /* SVID version: non-zero arg --> no break */
3306 /* non-zero arg means wait for all output data
3307 * to be sent (performed above) but don't send break.
3308 * This is used by the tcdrain() termios function.
3311 return send_break(tty, 250);
3313 case TCSBRKP: /* support for POSIX tcsendbreak() */
3314 return send_break(tty, arg ? arg*100 : 250);
3317 return tty_tiocmget(tty, file, p);
3322 return tty_tiocmset(tty, file, cmd, p);
3324 if (tty->driver->ioctl) {
3325 retval = (tty->driver->ioctl)(tty, file, cmd, arg);
3326 if (retval != -ENOIOCTLCMD)
3329 ld = tty_ldisc_ref_wait(tty);
3332 retval = ld->ioctl(tty, file, cmd, arg);
3333 if (retval == -ENOIOCTLCMD)
3336 tty_ldisc_deref(ld);
3342 * This implements the "Secure Attention Key" --- the idea is to
3343 * prevent trojan horses by killing all processes associated with this
3344 * tty when the user hits the "Secure Attention Key". Required for
3345 * super-paranoid applications --- see the Orange Book for more details.
3347 * This code could be nicer; ideally it should send a HUP, wait a few
3348 * seconds, then send a INT, and then a KILL signal. But you then
3349 * have to coordinate with the init process, since all processes associated
3350 * with the current tty must be dead before the new getty is allowed
3353 * Now, if it would be correct ;-/ The current code has a nasty hole -
3354 * it doesn't catch files in flight. We may send the descriptor to ourselves
3355 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
3357 * Nasty bug: do_SAK is being called in interrupt context. This can
3358 * deadlock. We punt it up to process context. AKPM - 16Mar2001
3360 void __do_SAK(struct tty_struct *tty)
3365 struct task_struct *g, *p;
3366 struct pid *session;
3369 struct fdtable *fdt;
3373 session = tty->session;
3375 tty_ldisc_flush(tty);
3377 if (tty->driver->flush_buffer)
3378 tty->driver->flush_buffer(tty);
3380 read_lock(&tasklist_lock);
3381 /* Kill the entire session */
3382 do_each_pid_task(session, PIDTYPE_SID, p) {
3383 printk(KERN_NOTICE "SAK: killed process %d"
3384 " (%s): process_session(p)==tty->session\n",
3386 send_sig(SIGKILL, p, 1);
3387 } while_each_pid_task(session, PIDTYPE_SID, p);
3388 /* Now kill any processes that happen to have the
3391 do_each_thread(g, p) {
3392 if (p->signal->tty == tty) {
3393 printk(KERN_NOTICE "SAK: killed process %d"
3394 " (%s): process_session(p)==tty->session\n",
3396 send_sig(SIGKILL, p, 1);
3402 * We don't take a ref to the file, so we must
3403 * hold ->file_lock instead.
3405 spin_lock(&p->files->file_lock);
3406 fdt = files_fdtable(p->files);
3407 for (i=0; i < fdt->max_fds; i++) {
3408 filp = fcheck_files(p->files, i);
3411 if (filp->f_op->read == tty_read &&
3412 filp->private_data == tty) {
3413 printk(KERN_NOTICE "SAK: killed process %d"
3414 " (%s): fd#%d opened to the tty\n",
3415 p->pid, p->comm, i);
3416 force_sig(SIGKILL, p);
3420 spin_unlock(&p->files->file_lock);
3423 } while_each_thread(g, p);
3424 read_unlock(&tasklist_lock);
3428 static void do_SAK_work(struct work_struct *work)
3430 struct tty_struct *tty =
3431 container_of(work, struct tty_struct, SAK_work);
3436 * The tq handling here is a little racy - tty->SAK_work may already be queued.
3437 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
3438 * the values which we write to it will be identical to the values which it
3439 * already has. --akpm
3441 void do_SAK(struct tty_struct *tty)
3445 schedule_work(&tty->SAK_work);
3448 EXPORT_SYMBOL(do_SAK);
3452 * @work: tty structure passed from work queue.
3454 * This routine is called out of the software interrupt to flush data
3455 * from the buffer chain to the line discipline.
3457 * Locking: holds tty->buf.lock to guard buffer list. Drops the lock
3458 * while invoking the line discipline receive_buf method. The
3459 * receive_buf method is single threaded for each tty instance.
3462 static void flush_to_ldisc(struct work_struct *work)
3464 struct tty_struct *tty =
3465 container_of(work, struct tty_struct, buf.work.work);
3466 unsigned long flags;
3467 struct tty_ldisc *disc;
3468 struct tty_buffer *tbuf, *head;
3470 unsigned char *flag_buf;
3472 disc = tty_ldisc_ref(tty);
3473 if (disc == NULL) /* !TTY_LDISC */
3476 spin_lock_irqsave(&tty->buf.lock, flags);
3477 head = tty->buf.head;
3479 tty->buf.head = NULL;
3481 int count = head->commit - head->read;
3483 if (head->next == NULL)
3487 tty_buffer_free(tty, tbuf);
3490 if (!tty->receive_room) {
3491 schedule_delayed_work(&tty->buf.work, 1);
3494 if (count > tty->receive_room)
3495 count = tty->receive_room;
3496 char_buf = head->char_buf_ptr + head->read;
3497 flag_buf = head->flag_buf_ptr + head->read;
3498 head->read += count;
3499 spin_unlock_irqrestore(&tty->buf.lock, flags);
3500 disc->receive_buf(tty, char_buf, flag_buf, count);
3501 spin_lock_irqsave(&tty->buf.lock, flags);
3503 tty->buf.head = head;
3505 spin_unlock_irqrestore(&tty->buf.lock, flags);
3507 tty_ldisc_deref(disc);
3511 * tty_flip_buffer_push - terminal
3514 * Queue a push of the terminal flip buffers to the line discipline. This
3515 * function must not be called from IRQ context if tty->low_latency is set.
3517 * In the event of the queue being busy for flipping the work will be
3518 * held off and retried later.
3520 * Locking: tty buffer lock. Driver locks in low latency mode.
3523 void tty_flip_buffer_push(struct tty_struct *tty)
3525 unsigned long flags;
3526 spin_lock_irqsave(&tty->buf.lock, flags);
3527 if (tty->buf.tail != NULL)
3528 tty->buf.tail->commit = tty->buf.tail->used;
3529 spin_unlock_irqrestore(&tty->buf.lock, flags);
3531 if (tty->low_latency)
3532 flush_to_ldisc(&tty->buf.work.work);
3534 schedule_delayed_work(&tty->buf.work, 1);
3537 EXPORT_SYMBOL(tty_flip_buffer_push);
3541 * initialize_tty_struct
3542 * @tty: tty to initialize
3544 * This subroutine initializes a tty structure that has been newly
3547 * Locking: none - tty in question must not be exposed at this point
3550 static void initialize_tty_struct(struct tty_struct *tty)
3552 memset(tty, 0, sizeof(struct tty_struct));
3553 tty->magic = TTY_MAGIC;
3554 tty_ldisc_assign(tty, tty_ldisc_get(N_TTY));
3555 tty->session = NULL;
3557 tty->overrun_time = jiffies;
3558 tty->buf.head = tty->buf.tail = NULL;
3559 tty_buffer_init(tty);
3560 INIT_DELAYED_WORK(&tty->buf.work, flush_to_ldisc);
3561 init_MUTEX(&tty->buf.pty_sem);
3562 mutex_init(&tty->termios_mutex);
3563 init_waitqueue_head(&tty->write_wait);
3564 init_waitqueue_head(&tty->read_wait);
3565 INIT_WORK(&tty->hangup_work, do_tty_hangup);
3566 mutex_init(&tty->atomic_read_lock);
3567 mutex_init(&tty->atomic_write_lock);
3568 spin_lock_init(&tty->read_lock);
3569 INIT_LIST_HEAD(&tty->tty_files);
3570 INIT_WORK(&tty->SAK_work, do_SAK_work);
3574 * The default put_char routine if the driver did not define one.
3577 static void tty_default_put_char(struct tty_struct *tty, unsigned char ch)
3579 tty->driver->write(tty, &ch, 1);
3582 static struct class *tty_class;
3585 * tty_register_device - register a tty device
3586 * @driver: the tty driver that describes the tty device
3587 * @index: the index in the tty driver for this tty device
3588 * @device: a struct device that is associated with this tty device.
3589 * This field is optional, if there is no known struct device
3590 * for this tty device it can be set to NULL safely.
3592 * Returns a pointer to the struct device for this tty device
3593 * (or ERR_PTR(-EFOO) on error).
3595 * This call is required to be made to register an individual tty device
3596 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3597 * that bit is not set, this function should not be called by a tty
3603 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
3604 struct device *device)
3607 dev_t dev = MKDEV(driver->major, driver->minor_start) + index;
3609 if (index >= driver->num) {
3610 printk(KERN_ERR "Attempt to register invalid tty line number "
3612 return ERR_PTR(-EINVAL);
3615 if (driver->type == TTY_DRIVER_TYPE_PTY)
3616 pty_line_name(driver, index, name);
3618 tty_line_name(driver, index, name);
3620 return device_create(tty_class, device, dev, name);
3624 * tty_unregister_device - unregister a tty device
3625 * @driver: the tty driver that describes the tty device
3626 * @index: the index in the tty driver for this tty device
3628 * If a tty device is registered with a call to tty_register_device() then
3629 * this function must be called when the tty device is gone.
3634 void tty_unregister_device(struct tty_driver *driver, unsigned index)
3636 device_destroy(tty_class, MKDEV(driver->major, driver->minor_start) + index);
3639 EXPORT_SYMBOL(tty_register_device);
3640 EXPORT_SYMBOL(tty_unregister_device);
3642 struct tty_driver *alloc_tty_driver(int lines)
3644 struct tty_driver *driver;
3646 driver = kmalloc(sizeof(struct tty_driver), GFP_KERNEL);
3648 memset(driver, 0, sizeof(struct tty_driver));
3649 driver->magic = TTY_DRIVER_MAGIC;
3650 driver->num = lines;
3651 /* later we'll move allocation of tables here */
3656 void put_tty_driver(struct tty_driver *driver)
3661 void tty_set_operations(struct tty_driver *driver,
3662 const struct tty_operations *op)
3664 driver->open = op->open;
3665 driver->close = op->close;
3666 driver->write = op->write;
3667 driver->put_char = op->put_char;
3668 driver->flush_chars = op->flush_chars;
3669 driver->write_room = op->write_room;
3670 driver->chars_in_buffer = op->chars_in_buffer;
3671 driver->ioctl = op->ioctl;
3672 driver->set_termios = op->set_termios;
3673 driver->throttle = op->throttle;
3674 driver->unthrottle = op->unthrottle;
3675 driver->stop = op->stop;
3676 driver->start = op->start;
3677 driver->hangup = op->hangup;
3678 driver->break_ctl = op->break_ctl;
3679 driver->flush_buffer = op->flush_buffer;
3680 driver->set_ldisc = op->set_ldisc;
3681 driver->wait_until_sent = op->wait_until_sent;
3682 driver->send_xchar = op->send_xchar;
3683 driver->read_proc = op->read_proc;
3684 driver->write_proc = op->write_proc;
3685 driver->tiocmget = op->tiocmget;
3686 driver->tiocmset = op->tiocmset;
3690 EXPORT_SYMBOL(alloc_tty_driver);
3691 EXPORT_SYMBOL(put_tty_driver);
3692 EXPORT_SYMBOL(tty_set_operations);
3695 * Called by a tty driver to register itself.
3697 int tty_register_driver(struct tty_driver *driver)
3704 if (driver->flags & TTY_DRIVER_INSTALLED)
3707 if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
3708 p = kmalloc(driver->num * 3 * sizeof(void *), GFP_KERNEL);
3711 memset(p, 0, driver->num * 3 * sizeof(void *));
3714 if (!driver->major) {
3715 error = alloc_chrdev_region(&dev, driver->minor_start, driver->num,
3718 driver->major = MAJOR(dev);
3719 driver->minor_start = MINOR(dev);
3722 dev = MKDEV(driver->major, driver->minor_start);
3723 error = register_chrdev_region(dev, driver->num, driver->name);
3731 driver->ttys = (struct tty_struct **)p;
3732 driver->termios = (struct ktermios **)(p + driver->num);
3733 driver->termios_locked = (struct ktermios **)(p + driver->num * 2);
3735 driver->ttys = NULL;
3736 driver->termios = NULL;
3737 driver->termios_locked = NULL;
3740 cdev_init(&driver->cdev, &tty_fops);
3741 driver->cdev.owner = driver->owner;
3742 error = cdev_add(&driver->cdev, dev, driver->num);
3744 unregister_chrdev_region(dev, driver->num);
3745 driver->ttys = NULL;
3746 driver->termios = driver->termios_locked = NULL;
3751 if (!driver->put_char)
3752 driver->put_char = tty_default_put_char;
3754 list_add(&driver->tty_drivers, &tty_drivers);
3756 if ( !(driver->flags & TTY_DRIVER_DYNAMIC_DEV) ) {
3757 for(i = 0; i < driver->num; i++)
3758 tty_register_device(driver, i, NULL);
3760 proc_tty_register_driver(driver);
3764 EXPORT_SYMBOL(tty_register_driver);
3767 * Called by a tty driver to unregister itself.
3769 int tty_unregister_driver(struct tty_driver *driver)
3772 struct ktermios *tp;
3775 if (driver->refcount)
3778 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3781 list_del(&driver->tty_drivers);
3784 * Free the termios and termios_locked structures because
3785 * we don't want to get memory leaks when modular tty
3786 * drivers are removed from the kernel.
3788 for (i = 0; i < driver->num; i++) {
3789 tp = driver->termios[i];
3791 driver->termios[i] = NULL;
3794 tp = driver->termios_locked[i];
3796 driver->termios_locked[i] = NULL;
3799 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3800 tty_unregister_device(driver, i);
3803 proc_tty_unregister_driver(driver);
3804 driver->ttys = NULL;
3805 driver->termios = driver->termios_locked = NULL;
3807 cdev_del(&driver->cdev);
3810 EXPORT_SYMBOL(tty_unregister_driver);
3812 dev_t tty_devnum(struct tty_struct *tty)
3814 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3816 EXPORT_SYMBOL(tty_devnum);
3818 void proc_clear_tty(struct task_struct *p)
3820 spin_lock_irq(&p->sighand->siglock);
3821 p->signal->tty = NULL;
3822 spin_unlock_irq(&p->sighand->siglock);
3824 EXPORT_SYMBOL(proc_clear_tty);
3826 static struct pid *__proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3828 struct pid *old_pgrp;
3830 tty->session = get_pid(task_session(tsk));
3831 tty->pgrp = get_pid(task_pgrp(tsk));
3833 old_pgrp = tsk->signal->tty_old_pgrp;
3834 tsk->signal->tty = tty;
3835 tsk->signal->tty_old_pgrp = NULL;
3839 void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3841 struct pid *old_pgrp;
3843 spin_lock_irq(&tsk->sighand->siglock);
3844 old_pgrp = __proc_set_tty(tsk, tty);
3845 spin_unlock_irq(&tsk->sighand->siglock);
3850 struct tty_struct *get_current_tty(void)
3852 struct tty_struct *tty;
3853 WARN_ON_ONCE(!mutex_is_locked(&tty_mutex));
3854 tty = current->signal->tty;
3856 * session->tty can be changed/cleared from under us, make sure we
3857 * issue the load. The obtained pointer, when not NULL, is valid as
3858 * long as we hold tty_mutex.
3863 EXPORT_SYMBOL_GPL(get_current_tty);
3866 * Initialize the console device. This is called *early*, so
3867 * we can't necessarily depend on lots of kernel help here.
3868 * Just do some early initializations, and do the complex setup
3871 void __init console_init(void)
3875 /* Setup the default TTY line discipline. */
3876 (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY);
3879 * set up the console device so that later boot sequences can
3880 * inform about problems etc..
3882 #ifdef CONFIG_EARLY_PRINTK
3883 disable_early_printk();
3885 call = __con_initcall_start;
3886 while (call < __con_initcall_end) {
3893 extern int vty_init(void);
3896 static int __init tty_class_init(void)
3898 tty_class = class_create(THIS_MODULE, "tty");
3899 if (IS_ERR(tty_class))
3900 return PTR_ERR(tty_class);
3904 postcore_initcall(tty_class_init);
3906 /* 3/2004 jmc: why do these devices exist? */
3908 static struct cdev tty_cdev, console_cdev;
3909 #ifdef CONFIG_UNIX98_PTYS
3910 static struct cdev ptmx_cdev;
3913 static struct cdev vc0_cdev;
3917 * Ok, now we can initialize the rest of the tty devices and can count
3918 * on memory allocations, interrupts etc..
3920 static int __init tty_init(void)
3922 cdev_init(&tty_cdev, &tty_fops);
3923 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3924 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3925 panic("Couldn't register /dev/tty driver\n");
3926 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), "tty");
3928 cdev_init(&console_cdev, &console_fops);
3929 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3930 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3931 panic("Couldn't register /dev/console driver\n");
3932 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 1), "console");
3934 #ifdef CONFIG_UNIX98_PTYS
3935 cdev_init(&ptmx_cdev, &ptmx_fops);
3936 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
3937 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
3938 panic("Couldn't register /dev/ptmx driver\n");
3939 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), "ptmx");
3943 cdev_init(&vc0_cdev, &console_fops);
3944 if (cdev_add(&vc0_cdev, MKDEV(TTY_MAJOR, 0), 1) ||
3945 register_chrdev_region(MKDEV(TTY_MAJOR, 0), 1, "/dev/vc/0") < 0)
3946 panic("Couldn't register /dev/tty0 driver\n");
3947 device_create(tty_class, NULL, MKDEV(TTY_MAJOR, 0), "tty0");
3953 module_init(tty_init);