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 static void initialize_tty_struct(struct tty_struct *tty);
146 static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
147 static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
148 ssize_t redirected_tty_write(struct file *, const char __user *, size_t, loff_t *);
149 static unsigned int tty_poll(struct file *, poll_table *);
150 static int tty_open(struct inode *, struct file *);
151 static int tty_release(struct inode *, struct file *);
152 int tty_ioctl(struct inode * inode, struct file * file,
153 unsigned int cmd, unsigned long arg);
155 static long tty_compat_ioctl(struct file * file, unsigned int cmd,
158 #define tty_compat_ioctl NULL
160 static int tty_fasync(int fd, struct file * filp, int on);
161 static void release_tty(struct tty_struct *tty, int idx);
162 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
163 static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
166 * alloc_tty_struct - allocate a tty object
168 * Return a new empty tty structure. The data fields have not
169 * been initialized in any way but has been zeroed
174 static struct tty_struct *alloc_tty_struct(void)
176 return kzalloc(sizeof(struct tty_struct), GFP_KERNEL);
179 static void tty_buffer_free_all(struct tty_struct *);
182 * free_tty_struct - free a disused tty
183 * @tty: tty struct to free
185 * Free the write buffers, tty queue and tty memory itself.
187 * Locking: none. Must be called after tty is definitely unused
190 static inline void free_tty_struct(struct tty_struct *tty)
192 kfree(tty->write_buf);
193 tty_buffer_free_all(tty);
197 #define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base)
200 * tty_name - return tty naming
201 * @tty: tty structure
202 * @buf: buffer for output
204 * Convert a tty structure into a name. The name reflects the kernel
205 * naming policy and if udev is in use may not reflect user space
210 char *tty_name(struct tty_struct *tty, char *buf)
212 if (!tty) /* Hmm. NULL pointer. That's fun. */
213 strcpy(buf, "NULL tty");
215 strcpy(buf, tty->name);
219 EXPORT_SYMBOL(tty_name);
221 int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
224 #ifdef TTY_PARANOIA_CHECK
227 "null TTY for (%d:%d) in %s\n",
228 imajor(inode), iminor(inode), routine);
231 if (tty->magic != TTY_MAGIC) {
233 "bad magic number for tty struct (%d:%d) in %s\n",
234 imajor(inode), iminor(inode), routine);
241 static int check_tty_count(struct tty_struct *tty, const char *routine)
243 #ifdef CHECK_TTY_COUNT
248 list_for_each(p, &tty->tty_files) {
252 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
253 tty->driver->subtype == PTY_TYPE_SLAVE &&
254 tty->link && tty->link->count)
256 if (tty->count != count) {
257 printk(KERN_WARNING "Warning: dev (%s) tty->count(%d) "
258 "!= #fd's(%d) in %s\n",
259 tty->name, tty->count, count, routine);
267 * Tty buffer allocation management
271 * tty_buffer_free_all - free buffers used by a tty
272 * @tty: tty to free from
274 * Remove all the buffers pending on a tty whether queued with data
275 * or in the free ring. Must be called when the tty is no longer in use
280 static void tty_buffer_free_all(struct tty_struct *tty)
282 struct tty_buffer *thead;
283 while((thead = tty->buf.head) != NULL) {
284 tty->buf.head = thead->next;
287 while((thead = tty->buf.free) != NULL) {
288 tty->buf.free = thead->next;
291 tty->buf.tail = NULL;
292 tty->buf.memory_used = 0;
296 * tty_buffer_init - prepare a tty buffer structure
297 * @tty: tty to initialise
299 * Set up the initial state of the buffer management for a tty device.
300 * Must be called before the other tty buffer functions are used.
305 static void tty_buffer_init(struct tty_struct *tty)
307 spin_lock_init(&tty->buf.lock);
308 tty->buf.head = NULL;
309 tty->buf.tail = NULL;
310 tty->buf.free = NULL;
311 tty->buf.memory_used = 0;
315 * tty_buffer_alloc - allocate a tty buffer
317 * @size: desired size (characters)
319 * Allocate a new tty buffer to hold the desired number of characters.
320 * Return NULL if out of memory or the allocation would exceed the
323 * Locking: Caller must hold tty->buf.lock
326 static struct tty_buffer *tty_buffer_alloc(struct tty_struct *tty, size_t size)
328 struct tty_buffer *p;
330 if (tty->buf.memory_used + size > 65536)
332 p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC);
340 p->char_buf_ptr = (char *)(p->data);
341 p->flag_buf_ptr = (unsigned char *)p->char_buf_ptr + size;
342 tty->buf.memory_used += size;
347 * tty_buffer_free - free a tty buffer
348 * @tty: tty owning the buffer
349 * @b: the buffer to free
351 * Free a tty buffer, or add it to the free list according to our
354 * Locking: Caller must hold tty->buf.lock
357 static void tty_buffer_free(struct tty_struct *tty, struct tty_buffer *b)
359 /* Dumb strategy for now - should keep some stats */
360 tty->buf.memory_used -= b->size;
361 WARN_ON(tty->buf.memory_used < 0);
366 b->next = tty->buf.free;
372 * tty_buffer_flush - flush full tty buffers
375 * flush all the buffers containing receive data
380 static void tty_buffer_flush(struct tty_struct *tty)
382 struct tty_buffer *thead;
385 spin_lock_irqsave(&tty->buf.lock, flags);
386 while((thead = tty->buf.head) != NULL) {
387 tty->buf.head = thead->next;
388 tty_buffer_free(tty, thead);
390 tty->buf.tail = NULL;
391 spin_unlock_irqrestore(&tty->buf.lock, flags);
395 * tty_buffer_find - find a free tty buffer
396 * @tty: tty owning the buffer
397 * @size: characters wanted
399 * Locate an existing suitable tty buffer or if we are lacking one then
400 * allocate a new one. We round our buffers off in 256 character chunks
401 * to get better allocation behaviour.
403 * Locking: Caller must hold tty->buf.lock
406 static struct tty_buffer *tty_buffer_find(struct tty_struct *tty, size_t size)
408 struct tty_buffer **tbh = &tty->buf.free;
409 while((*tbh) != NULL) {
410 struct tty_buffer *t = *tbh;
411 if(t->size >= size) {
417 tty->buf.memory_used += t->size;
420 tbh = &((*tbh)->next);
422 /* Round the buffer size out */
423 size = (size + 0xFF) & ~ 0xFF;
424 return tty_buffer_alloc(tty, size);
425 /* Should possibly check if this fails for the largest buffer we
426 have queued and recycle that ? */
430 * tty_buffer_request_room - grow tty buffer if needed
431 * @tty: tty structure
432 * @size: size desired
434 * Make at least size bytes of linear space available for the tty
435 * buffer. If we fail return the size we managed to find.
437 * Locking: Takes tty->buf.lock
439 int tty_buffer_request_room(struct tty_struct *tty, size_t size)
441 struct tty_buffer *b, *n;
445 spin_lock_irqsave(&tty->buf.lock, flags);
447 /* OPTIMISATION: We could keep a per tty "zero" sized buffer to
448 remove this conditional if its worth it. This would be invisible
450 if ((b = tty->buf.tail) != NULL)
451 left = b->size - b->used;
456 /* This is the slow path - looking for new buffers to use */
457 if ((n = tty_buffer_find(tty, size)) != NULL) {
468 spin_unlock_irqrestore(&tty->buf.lock, flags);
471 EXPORT_SYMBOL_GPL(tty_buffer_request_room);
474 * tty_insert_flip_string - Add characters to the tty buffer
475 * @tty: tty structure
479 * Queue a series of bytes to the tty buffering. All the characters
480 * passed are marked as without error. Returns the number added.
482 * Locking: Called functions may take tty->buf.lock
485 int tty_insert_flip_string(struct tty_struct *tty, const unsigned char *chars,
490 int space = tty_buffer_request_room(tty, size - copied);
491 struct tty_buffer *tb = tty->buf.tail;
492 /* If there is no space then tb may be NULL */
493 if(unlikely(space == 0))
495 memcpy(tb->char_buf_ptr + tb->used, chars, space);
496 memset(tb->flag_buf_ptr + tb->used, TTY_NORMAL, space);
500 /* There is a small chance that we need to split the data over
501 several buffers. If this is the case we must loop */
502 } while (unlikely(size > copied));
505 EXPORT_SYMBOL(tty_insert_flip_string);
508 * tty_insert_flip_string_flags - Add characters to the tty buffer
509 * @tty: tty structure
514 * Queue a series of bytes to the tty buffering. For each character
515 * the flags array indicates the status of the character. Returns the
518 * Locking: Called functions may take tty->buf.lock
521 int tty_insert_flip_string_flags(struct tty_struct *tty,
522 const unsigned char *chars, const char *flags, size_t size)
526 int space = tty_buffer_request_room(tty, size - copied);
527 struct tty_buffer *tb = tty->buf.tail;
528 /* If there is no space then tb may be NULL */
529 if(unlikely(space == 0))
531 memcpy(tb->char_buf_ptr + tb->used, chars, space);
532 memcpy(tb->flag_buf_ptr + tb->used, flags, space);
537 /* There is a small chance that we need to split the data over
538 several buffers. If this is the case we must loop */
539 } while (unlikely(size > copied));
542 EXPORT_SYMBOL(tty_insert_flip_string_flags);
545 * tty_schedule_flip - push characters to ldisc
546 * @tty: tty to push from
548 * Takes any pending buffers and transfers their ownership to the
549 * ldisc side of the queue. It then schedules those characters for
550 * processing by the line discipline.
552 * Locking: Takes tty->buf.lock
555 void tty_schedule_flip(struct tty_struct *tty)
558 spin_lock_irqsave(&tty->buf.lock, flags);
559 if (tty->buf.tail != NULL)
560 tty->buf.tail->commit = tty->buf.tail->used;
561 spin_unlock_irqrestore(&tty->buf.lock, flags);
562 schedule_delayed_work(&tty->buf.work, 1);
564 EXPORT_SYMBOL(tty_schedule_flip);
567 * tty_prepare_flip_string - make room for characters
569 * @chars: return pointer for character write area
570 * @size: desired size
572 * Prepare a block of space in the buffer for data. Returns the length
573 * available and buffer pointer to the space which is now allocated and
574 * accounted for as ready for normal characters. This is used for drivers
575 * that need their own block copy routines into the buffer. There is no
576 * guarantee the buffer is a DMA target!
578 * Locking: May call functions taking tty->buf.lock
581 int tty_prepare_flip_string(struct tty_struct *tty, unsigned char **chars, size_t size)
583 int space = tty_buffer_request_room(tty, size);
585 struct tty_buffer *tb = tty->buf.tail;
586 *chars = tb->char_buf_ptr + tb->used;
587 memset(tb->flag_buf_ptr + tb->used, TTY_NORMAL, space);
593 EXPORT_SYMBOL_GPL(tty_prepare_flip_string);
596 * tty_prepare_flip_string_flags - make room for characters
598 * @chars: return pointer for character write area
599 * @flags: return pointer for status flag write area
600 * @size: desired size
602 * Prepare a block of space in the buffer for data. Returns the length
603 * available and buffer pointer to the space which is now allocated and
604 * accounted for as ready for characters. This is used for drivers
605 * that need their own block copy routines into the buffer. There is no
606 * guarantee the buffer is a DMA target!
608 * Locking: May call functions taking tty->buf.lock
611 int tty_prepare_flip_string_flags(struct tty_struct *tty, unsigned char **chars, char **flags, size_t size)
613 int space = tty_buffer_request_room(tty, size);
615 struct tty_buffer *tb = tty->buf.tail;
616 *chars = tb->char_buf_ptr + tb->used;
617 *flags = tb->flag_buf_ptr + tb->used;
623 EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags);
628 * tty_set_termios_ldisc - set ldisc field
629 * @tty: tty structure
630 * @num: line discipline number
632 * This is probably overkill for real world processors but
633 * they are not on hot paths so a little discipline won't do
636 * Locking: takes termios_mutex
639 static void tty_set_termios_ldisc(struct tty_struct *tty, int num)
641 mutex_lock(&tty->termios_mutex);
642 tty->termios->c_line = num;
643 mutex_unlock(&tty->termios_mutex);
647 * This guards the refcounted line discipline lists. The lock
648 * must be taken with irqs off because there are hangup path
649 * callers who will do ldisc lookups and cannot sleep.
652 static DEFINE_SPINLOCK(tty_ldisc_lock);
653 static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_wait);
654 static struct tty_ldisc tty_ldiscs[NR_LDISCS]; /* line disc dispatch table */
657 * tty_register_ldisc - install a line discipline
658 * @disc: ldisc number
659 * @new_ldisc: pointer to the ldisc object
661 * Installs a new line discipline into the kernel. The discipline
662 * is set up as unreferenced and then made available to the kernel
663 * from this point onwards.
666 * takes tty_ldisc_lock to guard against ldisc races
669 int tty_register_ldisc(int disc, struct tty_ldisc *new_ldisc)
674 if (disc < N_TTY || disc >= NR_LDISCS)
677 spin_lock_irqsave(&tty_ldisc_lock, flags);
678 tty_ldiscs[disc] = *new_ldisc;
679 tty_ldiscs[disc].num = disc;
680 tty_ldiscs[disc].flags |= LDISC_FLAG_DEFINED;
681 tty_ldiscs[disc].refcount = 0;
682 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
686 EXPORT_SYMBOL(tty_register_ldisc);
689 * tty_unregister_ldisc - unload a line discipline
690 * @disc: ldisc number
691 * @new_ldisc: pointer to the ldisc object
693 * Remove a line discipline from the kernel providing it is not
697 * takes tty_ldisc_lock to guard against ldisc races
700 int tty_unregister_ldisc(int disc)
705 if (disc < N_TTY || disc >= NR_LDISCS)
708 spin_lock_irqsave(&tty_ldisc_lock, flags);
709 if (tty_ldiscs[disc].refcount)
712 tty_ldiscs[disc].flags &= ~LDISC_FLAG_DEFINED;
713 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
717 EXPORT_SYMBOL(tty_unregister_ldisc);
720 * tty_ldisc_get - take a reference to an ldisc
721 * @disc: ldisc number
723 * Takes a reference to a line discipline. Deals with refcounts and
724 * module locking counts. Returns NULL if the discipline is not available.
725 * Returns a pointer to the discipline and bumps the ref count if it is
729 * takes tty_ldisc_lock to guard against ldisc races
732 struct tty_ldisc *tty_ldisc_get(int disc)
735 struct tty_ldisc *ld;
737 if (disc < N_TTY || disc >= NR_LDISCS)
740 spin_lock_irqsave(&tty_ldisc_lock, flags);
742 ld = &tty_ldiscs[disc];
743 /* Check the entry is defined */
744 if(ld->flags & LDISC_FLAG_DEFINED)
746 /* If the module is being unloaded we can't use it */
747 if (!try_module_get(ld->owner))
754 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
758 EXPORT_SYMBOL_GPL(tty_ldisc_get);
761 * tty_ldisc_put - drop ldisc reference
762 * @disc: ldisc number
764 * Drop a reference to a line discipline. Manage refcounts and
765 * module usage counts
768 * takes tty_ldisc_lock to guard against ldisc races
771 void tty_ldisc_put(int disc)
773 struct tty_ldisc *ld;
776 BUG_ON(disc < N_TTY || disc >= NR_LDISCS);
778 spin_lock_irqsave(&tty_ldisc_lock, flags);
779 ld = &tty_ldiscs[disc];
780 BUG_ON(ld->refcount == 0);
782 module_put(ld->owner);
783 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
786 EXPORT_SYMBOL_GPL(tty_ldisc_put);
789 * tty_ldisc_assign - set ldisc on a tty
790 * @tty: tty to assign
791 * @ld: line discipline
793 * Install an instance of a line discipline into a tty structure. The
794 * ldisc must have a reference count above zero to ensure it remains/
795 * The tty instance refcount starts at zero.
798 * Caller must hold references
801 static void tty_ldisc_assign(struct tty_struct *tty, struct tty_ldisc *ld)
804 tty->ldisc.refcount = 0;
808 * tty_ldisc_try - internal helper
811 * Make a single attempt to grab and bump the refcount on
812 * the tty ldisc. Return 0 on failure or 1 on success. This is
813 * used to implement both the waiting and non waiting versions
816 * Locking: takes tty_ldisc_lock
819 static int tty_ldisc_try(struct tty_struct *tty)
822 struct tty_ldisc *ld;
825 spin_lock_irqsave(&tty_ldisc_lock, flags);
827 if(test_bit(TTY_LDISC, &tty->flags))
832 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
837 * tty_ldisc_ref_wait - wait for 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 * wait patiently until it changes.
844 * Note: Must not be called from an IRQ/timer context. The caller
845 * must also be careful not to hold other locks that will deadlock
846 * against a discipline change, such as an existing ldisc reference
847 * (which we check for)
849 * Locking: call functions take tty_ldisc_lock
852 struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty)
854 /* wait_event is a macro */
855 wait_event(tty_ldisc_wait, tty_ldisc_try(tty));
856 if(tty->ldisc.refcount == 0)
857 printk(KERN_ERR "tty_ldisc_ref_wait\n");
861 EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait);
864 * tty_ldisc_ref - get the tty ldisc
867 * Dereference the line discipline for the terminal and take a
868 * reference to it. If the line discipline is in flux then
869 * return NULL. Can be called from IRQ and timer functions.
871 * Locking: called functions take tty_ldisc_lock
874 struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty)
876 if(tty_ldisc_try(tty))
881 EXPORT_SYMBOL_GPL(tty_ldisc_ref);
884 * tty_ldisc_deref - free a tty ldisc reference
885 * @ld: reference to free up
887 * Undoes the effect of tty_ldisc_ref or tty_ldisc_ref_wait. May
888 * be called in IRQ context.
890 * Locking: takes tty_ldisc_lock
893 void tty_ldisc_deref(struct tty_ldisc *ld)
899 spin_lock_irqsave(&tty_ldisc_lock, flags);
900 if(ld->refcount == 0)
901 printk(KERN_ERR "tty_ldisc_deref: no references.\n");
904 if(ld->refcount == 0)
905 wake_up(&tty_ldisc_wait);
906 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
909 EXPORT_SYMBOL_GPL(tty_ldisc_deref);
912 * tty_ldisc_enable - allow ldisc use
913 * @tty: terminal to activate ldisc on
915 * Set the TTY_LDISC flag when the line discipline can be called
916 * again. Do neccessary wakeups for existing sleepers.
918 * Note: nobody should set this bit except via this function. Clearing
919 * directly is allowed.
922 static void tty_ldisc_enable(struct tty_struct *tty)
924 set_bit(TTY_LDISC, &tty->flags);
925 wake_up(&tty_ldisc_wait);
929 * tty_set_ldisc - set line discipline
930 * @tty: the terminal to set
931 * @ldisc: the line discipline
933 * Set the discipline of a tty line. Must be called from a process
936 * Locking: takes tty_ldisc_lock.
937 * called functions take termios_mutex
940 static int tty_set_ldisc(struct tty_struct *tty, int ldisc)
943 struct tty_ldisc o_ldisc;
947 struct tty_ldisc *ld;
948 struct tty_struct *o_tty;
950 if ((ldisc < N_TTY) || (ldisc >= NR_LDISCS))
955 ld = tty_ldisc_get(ldisc);
956 /* Eduardo Blanco <ejbs@cs.cs.com.uy> */
957 /* Cyrus Durgin <cider@speakeasy.org> */
959 request_module("tty-ldisc-%d", ldisc);
960 ld = tty_ldisc_get(ldisc);
966 * Problem: What do we do if this blocks ?
969 tty_wait_until_sent(tty, 0);
971 if (tty->ldisc.num == ldisc) {
972 tty_ldisc_put(ldisc);
977 * No more input please, we are switching. The new ldisc
978 * will update this value in the ldisc open function
981 tty->receive_room = 0;
983 o_ldisc = tty->ldisc;
987 * Make sure we don't change while someone holds a
988 * reference to the line discipline. The TTY_LDISC bit
989 * prevents anyone taking a reference once it is clear.
990 * We need the lock to avoid racing reference takers.
993 spin_lock_irqsave(&tty_ldisc_lock, flags);
994 if (tty->ldisc.refcount || (o_tty && o_tty->ldisc.refcount)) {
995 if(tty->ldisc.refcount) {
996 /* Free the new ldisc we grabbed. Must drop the lock
998 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
999 tty_ldisc_put(ldisc);
1001 * There are several reasons we may be busy, including
1002 * random momentary I/O traffic. We must therefore
1003 * retry. We could distinguish between blocking ops
1004 * and retries if we made tty_ldisc_wait() smarter. That
1005 * is up for discussion.
1007 if (wait_event_interruptible(tty_ldisc_wait, tty->ldisc.refcount == 0) < 0)
1008 return -ERESTARTSYS;
1011 if(o_tty && o_tty->ldisc.refcount) {
1012 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
1013 tty_ldisc_put(ldisc);
1014 if (wait_event_interruptible(tty_ldisc_wait, o_tty->ldisc.refcount == 0) < 0)
1015 return -ERESTARTSYS;
1020 /* if the TTY_LDISC bit is set, then we are racing against another ldisc change */
1022 if (!test_bit(TTY_LDISC, &tty->flags)) {
1023 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
1024 tty_ldisc_put(ldisc);
1025 ld = tty_ldisc_ref_wait(tty);
1026 tty_ldisc_deref(ld);
1030 clear_bit(TTY_LDISC, &tty->flags);
1032 clear_bit(TTY_LDISC, &o_tty->flags);
1033 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
1036 * From this point on we know nobody has an ldisc
1037 * usage reference, nor can they obtain one until
1038 * we say so later on.
1041 work = cancel_delayed_work(&tty->buf.work);
1043 * Wait for ->hangup_work and ->buf.work handlers to terminate
1046 flush_scheduled_work();
1047 /* Shutdown the current discipline. */
1048 if (tty->ldisc.close)
1049 (tty->ldisc.close)(tty);
1051 /* Now set up the new line discipline. */
1052 tty_ldisc_assign(tty, ld);
1053 tty_set_termios_ldisc(tty, ldisc);
1054 if (tty->ldisc.open)
1055 retval = (tty->ldisc.open)(tty);
1057 tty_ldisc_put(ldisc);
1058 /* There is an outstanding reference here so this is safe */
1059 tty_ldisc_assign(tty, tty_ldisc_get(o_ldisc.num));
1060 tty_set_termios_ldisc(tty, tty->ldisc.num);
1061 if (tty->ldisc.open && (tty->ldisc.open(tty) < 0)) {
1062 tty_ldisc_put(o_ldisc.num);
1063 /* This driver is always present */
1064 tty_ldisc_assign(tty, tty_ldisc_get(N_TTY));
1065 tty_set_termios_ldisc(tty, N_TTY);
1066 if (tty->ldisc.open) {
1067 int r = tty->ldisc.open(tty);
1070 panic("Couldn't open N_TTY ldisc for "
1072 tty_name(tty, buf), r);
1076 /* At this point we hold a reference to the new ldisc and a
1077 a reference to the old ldisc. If we ended up flipping back
1078 to the existing ldisc we have two references to it */
1080 if (tty->ldisc.num != o_ldisc.num && tty->driver->set_ldisc)
1081 tty->driver->set_ldisc(tty);
1083 tty_ldisc_put(o_ldisc.num);
1086 * Allow ldisc referencing to occur as soon as the driver
1087 * ldisc callback completes.
1090 tty_ldisc_enable(tty);
1092 tty_ldisc_enable(o_tty);
1094 /* Restart it in case no characters kick it off. Safe if
1097 schedule_delayed_work(&tty->buf.work, 1);
1102 * get_tty_driver - find device of a tty
1103 * @dev_t: device identifier
1104 * @index: returns the index of the tty
1106 * This routine returns a tty driver structure, given a device number
1107 * and also passes back the index number.
1109 * Locking: caller must hold tty_mutex
1112 static struct tty_driver *get_tty_driver(dev_t device, int *index)
1114 struct tty_driver *p;
1116 list_for_each_entry(p, &tty_drivers, tty_drivers) {
1117 dev_t base = MKDEV(p->major, p->minor_start);
1118 if (device < base || device >= base + p->num)
1120 *index = device - base;
1127 * tty_check_change - check for POSIX terminal changes
1128 * @tty: tty to check
1130 * If we try to write to, or set the state of, a terminal and we're
1131 * not in the foreground, send a SIGTTOU. If the signal is blocked or
1132 * ignored, go ahead and perform the operation. (POSIX 7.2)
1137 int tty_check_change(struct tty_struct * tty)
1139 if (current->signal->tty != tty)
1142 printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");
1145 if (task_pgrp(current) == tty->pgrp)
1147 if (is_ignored(SIGTTOU))
1149 if (is_current_pgrp_orphaned())
1151 (void) kill_pgrp(task_pgrp(current), SIGTTOU, 1);
1152 return -ERESTARTSYS;
1155 EXPORT_SYMBOL(tty_check_change);
1157 static ssize_t hung_up_tty_read(struct file * file, char __user * buf,
1158 size_t count, loff_t *ppos)
1163 static ssize_t hung_up_tty_write(struct file * file, const char __user * buf,
1164 size_t count, loff_t *ppos)
1169 /* No kernel lock held - none needed ;) */
1170 static unsigned int hung_up_tty_poll(struct file * filp, poll_table * wait)
1172 return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM;
1175 static long hung_up_tty_ioctl(struct file * file,
1176 unsigned int cmd, unsigned long arg)
1178 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
1181 static const struct file_operations tty_fops = {
1182 .llseek = no_llseek,
1187 .compat_ioctl = tty_compat_ioctl,
1189 .release = tty_release,
1190 .fasync = tty_fasync,
1193 #ifdef CONFIG_UNIX98_PTYS
1194 static const struct file_operations ptmx_fops = {
1195 .llseek = no_llseek,
1200 .compat_ioctl = tty_compat_ioctl,
1202 .release = tty_release,
1203 .fasync = tty_fasync,
1207 static const struct file_operations console_fops = {
1208 .llseek = no_llseek,
1210 .write = redirected_tty_write,
1213 .compat_ioctl = tty_compat_ioctl,
1215 .release = tty_release,
1216 .fasync = tty_fasync,
1219 static const struct file_operations hung_up_tty_fops = {
1220 .llseek = no_llseek,
1221 .read = hung_up_tty_read,
1222 .write = hung_up_tty_write,
1223 .poll = hung_up_tty_poll,
1224 .unlocked_ioctl = hung_up_tty_ioctl,
1225 .compat_ioctl = hung_up_tty_ioctl,
1226 .release = tty_release,
1229 static DEFINE_SPINLOCK(redirect_lock);
1230 static struct file *redirect;
1233 * tty_wakeup - request more data
1236 * Internal and external helper for wakeups of tty. This function
1237 * informs the line discipline if present that the driver is ready
1238 * to receive more output data.
1241 void tty_wakeup(struct tty_struct *tty)
1243 struct tty_ldisc *ld;
1245 if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
1246 ld = tty_ldisc_ref(tty);
1248 if(ld->write_wakeup)
1249 ld->write_wakeup(tty);
1250 tty_ldisc_deref(ld);
1253 wake_up_interruptible(&tty->write_wait);
1256 EXPORT_SYMBOL_GPL(tty_wakeup);
1259 * tty_ldisc_flush - flush line discipline queue
1262 * Flush the line discipline queue (if any) for this tty. If there
1263 * is no line discipline active this is a no-op.
1266 void tty_ldisc_flush(struct tty_struct *tty)
1268 struct tty_ldisc *ld = tty_ldisc_ref(tty);
1270 if(ld->flush_buffer)
1271 ld->flush_buffer(tty);
1272 tty_ldisc_deref(ld);
1274 tty_buffer_flush(tty);
1277 EXPORT_SYMBOL_GPL(tty_ldisc_flush);
1280 * tty_reset_termios - reset terminal state
1281 * @tty: tty to reset
1283 * Restore a terminal to the driver default state
1286 static void tty_reset_termios(struct tty_struct *tty)
1288 mutex_lock(&tty->termios_mutex);
1289 *tty->termios = tty->driver->init_termios;
1290 tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
1291 tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
1292 mutex_unlock(&tty->termios_mutex);
1296 * do_tty_hangup - actual handler for hangup events
1299 * This can be called by the "eventd" kernel thread. That is process
1300 * synchronous but doesn't hold any locks, so we need to make sure we
1301 * have the appropriate locks for what we're doing.
1303 * The hangup event clears any pending redirections onto the hung up
1304 * device. It ensures future writes will error and it does the needed
1305 * line discipline hangup and signal delivery. The tty object itself
1310 * redirect lock for undoing redirection
1311 * file list lock for manipulating list of ttys
1312 * tty_ldisc_lock from called functions
1313 * termios_mutex resetting termios data
1314 * tasklist_lock to walk task list for hangup event
1315 * ->siglock to protect ->signal/->sighand
1317 static void do_tty_hangup(struct work_struct *work)
1319 struct tty_struct *tty =
1320 container_of(work, struct tty_struct, hangup_work);
1321 struct file * cons_filp = NULL;
1322 struct file *filp, *f = NULL;
1323 struct task_struct *p;
1324 struct tty_ldisc *ld;
1325 int closecount = 0, n;
1330 /* inuse_filps is protected by the single kernel lock */
1333 spin_lock(&redirect_lock);
1334 if (redirect && redirect->private_data == tty) {
1338 spin_unlock(&redirect_lock);
1340 check_tty_count(tty, "do_tty_hangup");
1342 /* This breaks for file handles being sent over AF_UNIX sockets ? */
1343 list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) {
1344 if (filp->f_op->write == redirected_tty_write)
1346 if (filp->f_op->write != tty_write)
1349 tty_fasync(-1, filp, 0); /* can't block */
1350 filp->f_op = &hung_up_tty_fops;
1354 /* FIXME! What are the locking issues here? This may me overdoing things..
1355 * this question is especially important now that we've removed the irqlock. */
1357 ld = tty_ldisc_ref(tty);
1358 if(ld != NULL) /* We may have no line discipline at this point */
1360 if (ld->flush_buffer)
1361 ld->flush_buffer(tty);
1362 if (tty->driver->flush_buffer)
1363 tty->driver->flush_buffer(tty);
1364 if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) &&
1366 ld->write_wakeup(tty);
1371 /* FIXME: Once we trust the LDISC code better we can wait here for
1372 ldisc completion and fix the driver call race */
1374 wake_up_interruptible(&tty->write_wait);
1375 wake_up_interruptible(&tty->read_wait);
1378 * Shutdown the current line discipline, and reset it to
1381 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1382 tty_reset_termios(tty);
1384 /* Defer ldisc switch */
1385 /* tty_deferred_ldisc_switch(N_TTY);
1387 This should get done automatically when the port closes and
1388 tty_release is called */
1390 read_lock(&tasklist_lock);
1392 do_each_pid_task(tty->session, PIDTYPE_SID, p) {
1393 spin_lock_irq(&p->sighand->siglock);
1394 if (p->signal->tty == tty)
1395 p->signal->tty = NULL;
1396 if (!p->signal->leader) {
1397 spin_unlock_irq(&p->sighand->siglock);
1400 __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
1401 __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
1402 put_pid(p->signal->tty_old_pgrp); /* A noop */
1404 p->signal->tty_old_pgrp = get_pid(tty->pgrp);
1405 spin_unlock_irq(&p->sighand->siglock);
1406 } while_each_pid_task(tty->session, PIDTYPE_SID, p);
1408 read_unlock(&tasklist_lock);
1411 put_pid(tty->session);
1413 tty->session = NULL;
1415 tty->ctrl_status = 0;
1417 * If one of the devices matches a console pointer, we
1418 * cannot just call hangup() because that will cause
1419 * tty->count and state->count to go out of sync.
1420 * So we just call close() the right number of times.
1423 if (tty->driver->close)
1424 for (n = 0; n < closecount; n++)
1425 tty->driver->close(tty, cons_filp);
1426 } else if (tty->driver->hangup)
1427 (tty->driver->hangup)(tty);
1429 /* We don't want to have driver/ldisc interactions beyond
1430 the ones we did here. The driver layer expects no
1431 calls after ->hangup() from the ldisc side. However we
1432 can't yet guarantee all that */
1434 set_bit(TTY_HUPPED, &tty->flags);
1436 tty_ldisc_enable(tty);
1437 tty_ldisc_deref(ld);
1445 * tty_hangup - trigger a hangup event
1446 * @tty: tty to hangup
1448 * A carrier loss (virtual or otherwise) has occurred on this like
1449 * schedule a hangup sequence to run after this event.
1452 void tty_hangup(struct tty_struct * tty)
1454 #ifdef TTY_DEBUG_HANGUP
1457 printk(KERN_DEBUG "%s hangup...\n", tty_name(tty, buf));
1459 schedule_work(&tty->hangup_work);
1462 EXPORT_SYMBOL(tty_hangup);
1465 * tty_vhangup - process vhangup
1466 * @tty: tty to hangup
1468 * The user has asked via system call for the terminal to be hung up.
1469 * We do this synchronously so that when the syscall returns the process
1470 * is complete. That guarantee is neccessary for security reasons.
1473 void tty_vhangup(struct tty_struct * tty)
1475 #ifdef TTY_DEBUG_HANGUP
1478 printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf));
1480 do_tty_hangup(&tty->hangup_work);
1482 EXPORT_SYMBOL(tty_vhangup);
1485 * tty_hung_up_p - was tty hung up
1486 * @filp: file pointer of tty
1488 * Return true if the tty has been subject to a vhangup or a carrier
1492 int tty_hung_up_p(struct file * filp)
1494 return (filp->f_op == &hung_up_tty_fops);
1497 EXPORT_SYMBOL(tty_hung_up_p);
1499 static void session_clear_tty(struct pid *session)
1501 struct task_struct *p;
1502 do_each_pid_task(session, PIDTYPE_SID, p) {
1504 } while_each_pid_task(session, PIDTYPE_SID, p);
1508 * disassociate_ctty - disconnect controlling tty
1509 * @on_exit: true if exiting so need to "hang up" the session
1511 * This function is typically called only by the session leader, when
1512 * it wants to disassociate itself from its controlling tty.
1514 * It performs the following functions:
1515 * (1) Sends a SIGHUP and SIGCONT to the foreground process group
1516 * (2) Clears the tty from being controlling the session
1517 * (3) Clears the controlling tty for all processes in the
1520 * The argument on_exit is set to 1 if called when a process is
1521 * exiting; it is 0 if called by the ioctl TIOCNOTTY.
1524 * BKL is taken for hysterical raisins
1525 * tty_mutex is taken to protect tty
1526 * ->siglock is taken to protect ->signal/->sighand
1527 * tasklist_lock is taken to walk process list for sessions
1528 * ->siglock is taken to protect ->signal/->sighand
1531 void disassociate_ctty(int on_exit)
1533 struct tty_struct *tty;
1534 struct pid *tty_pgrp = NULL;
1538 mutex_lock(&tty_mutex);
1539 tty = get_current_tty();
1541 tty_pgrp = get_pid(tty->pgrp);
1542 mutex_unlock(&tty_mutex);
1543 /* XXX: here we race, there is nothing protecting tty */
1544 if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)
1546 } else if (on_exit) {
1547 struct pid *old_pgrp;
1548 spin_lock_irq(¤t->sighand->siglock);
1549 old_pgrp = current->signal->tty_old_pgrp;
1550 current->signal->tty_old_pgrp = NULL;
1551 spin_unlock_irq(¤t->sighand->siglock);
1553 kill_pgrp(old_pgrp, SIGHUP, on_exit);
1554 kill_pgrp(old_pgrp, SIGCONT, on_exit);
1557 mutex_unlock(&tty_mutex);
1562 kill_pgrp(tty_pgrp, SIGHUP, on_exit);
1564 kill_pgrp(tty_pgrp, SIGCONT, on_exit);
1568 spin_lock_irq(¤t->sighand->siglock);
1569 put_pid(current->signal->tty_old_pgrp);
1570 current->signal->tty_old_pgrp = NULL;
1571 spin_unlock_irq(¤t->sighand->siglock);
1573 mutex_lock(&tty_mutex);
1574 /* It is possible that do_tty_hangup has free'd this tty */
1575 tty = get_current_tty();
1577 put_pid(tty->session);
1579 tty->session = NULL;
1582 #ifdef TTY_DEBUG_HANGUP
1583 printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
1587 mutex_unlock(&tty_mutex);
1589 /* Now clear signal->tty under the lock */
1590 read_lock(&tasklist_lock);
1591 session_clear_tty(task_session(current));
1592 read_unlock(&tasklist_lock);
1598 * no_tty - Ensure the current process does not have a controlling tty
1602 struct task_struct *tsk = current;
1603 if (tsk->signal->leader)
1604 disassociate_ctty(0);
1605 proc_clear_tty(tsk);
1610 * stop_tty - propagate flow control
1613 * Perform flow control to the driver. For PTY/TTY pairs we
1614 * must also propagate the TIOCKPKT status. May be called
1615 * on an already stopped device and will not re-call the driver
1618 * This functionality is used by both the line disciplines for
1619 * halting incoming flow and by the driver. It may therefore be
1620 * called from any context, may be under the tty atomic_write_lock
1624 * Broken. Relies on BKL which is unsafe here.
1627 void stop_tty(struct tty_struct *tty)
1632 if (tty->link && tty->link->packet) {
1633 tty->ctrl_status &= ~TIOCPKT_START;
1634 tty->ctrl_status |= TIOCPKT_STOP;
1635 wake_up_interruptible(&tty->link->read_wait);
1637 if (tty->driver->stop)
1638 (tty->driver->stop)(tty);
1641 EXPORT_SYMBOL(stop_tty);
1644 * start_tty - propagate flow control
1645 * @tty: tty to start
1647 * Start a tty that has been stopped if at all possible. Perform
1648 * any neccessary wakeups and propagate the TIOCPKT status. If this
1649 * is the tty was previous stopped and is being started then the
1650 * driver start method is invoked and the line discipline woken.
1653 * Broken. Relies on BKL which is unsafe here.
1656 void start_tty(struct tty_struct *tty)
1658 if (!tty->stopped || tty->flow_stopped)
1661 if (tty->link && tty->link->packet) {
1662 tty->ctrl_status &= ~TIOCPKT_STOP;
1663 tty->ctrl_status |= TIOCPKT_START;
1664 wake_up_interruptible(&tty->link->read_wait);
1666 if (tty->driver->start)
1667 (tty->driver->start)(tty);
1669 /* If we have a running line discipline it may need kicking */
1673 EXPORT_SYMBOL(start_tty);
1676 * tty_read - read method for tty device files
1677 * @file: pointer to tty file
1679 * @count: size of user buffer
1682 * Perform the read system call function on this terminal device. Checks
1683 * for hung up devices before calling the line discipline method.
1686 * Locks the line discipline internally while needed
1687 * For historical reasons the line discipline read method is
1688 * invoked under the BKL. This will go away in time so do not rely on it
1689 * in new code. Multiple read calls may be outstanding in parallel.
1692 static ssize_t tty_read(struct file * file, char __user * buf, size_t count,
1696 struct tty_struct * tty;
1697 struct inode *inode;
1698 struct tty_ldisc *ld;
1700 tty = (struct tty_struct *)file->private_data;
1701 inode = file->f_path.dentry->d_inode;
1702 if (tty_paranoia_check(tty, inode, "tty_read"))
1704 if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags)))
1707 /* We want to wait for the line discipline to sort out in this
1709 ld = tty_ldisc_ref_wait(tty);
1712 i = (ld->read)(tty,file,buf,count);
1715 tty_ldisc_deref(ld);
1718 inode->i_atime = current_fs_time(inode->i_sb);
1723 * Split writes up in sane blocksizes to avoid
1724 * denial-of-service type attacks
1726 static inline ssize_t do_tty_write(
1727 ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
1728 struct tty_struct *tty,
1730 const char __user *buf,
1733 ssize_t ret = 0, written = 0;
1736 /* FIXME: O_NDELAY ... */
1737 if (mutex_lock_interruptible(&tty->atomic_write_lock)) {
1738 return -ERESTARTSYS;
1742 * We chunk up writes into a temporary buffer. This
1743 * simplifies low-level drivers immensely, since they
1744 * don't have locking issues and user mode accesses.
1746 * But if TTY_NO_WRITE_SPLIT is set, we should use a
1749 * The default chunk-size is 2kB, because the NTTY
1750 * layer has problems with bigger chunks. It will
1751 * claim to be able to handle more characters than
1754 * FIXME: This can probably go away now except that 64K chunks
1755 * are too likely to fail unless switched to vmalloc...
1758 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
1763 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
1764 if (tty->write_cnt < chunk) {
1770 buf = kmalloc(chunk, GFP_KERNEL);
1772 mutex_unlock(&tty->atomic_write_lock);
1775 kfree(tty->write_buf);
1776 tty->write_cnt = chunk;
1777 tty->write_buf = buf;
1780 /* Do the write .. */
1782 size_t size = count;
1786 if (copy_from_user(tty->write_buf, buf, size))
1789 ret = write(tty, file, tty->write_buf, size);
1799 if (signal_pending(current))
1804 struct inode *inode = file->f_path.dentry->d_inode;
1805 inode->i_mtime = current_fs_time(inode->i_sb);
1808 mutex_unlock(&tty->atomic_write_lock);
1814 * tty_write - write method for tty device file
1815 * @file: tty file pointer
1816 * @buf: user data to write
1817 * @count: bytes to write
1820 * Write data to a tty device via the line discipline.
1823 * Locks the line discipline as required
1824 * Writes to the tty driver are serialized by the atomic_write_lock
1825 * and are then processed in chunks to the device. The line discipline
1826 * write method will not be involked in parallel for each device
1827 * The line discipline write method is called under the big
1828 * kernel lock for historical reasons. New code should not rely on this.
1831 static ssize_t tty_write(struct file * file, const char __user * buf, size_t count,
1834 struct tty_struct * tty;
1835 struct inode *inode = file->f_path.dentry->d_inode;
1837 struct tty_ldisc *ld;
1839 tty = (struct tty_struct *)file->private_data;
1840 if (tty_paranoia_check(tty, inode, "tty_write"))
1842 if (!tty || !tty->driver->write || (test_bit(TTY_IO_ERROR, &tty->flags)))
1845 ld = tty_ldisc_ref_wait(tty);
1849 ret = do_tty_write(ld->write, tty, file, buf, count);
1850 tty_ldisc_deref(ld);
1854 ssize_t redirected_tty_write(struct file * file, const char __user * buf, size_t count,
1857 struct file *p = NULL;
1859 spin_lock(&redirect_lock);
1864 spin_unlock(&redirect_lock);
1868 res = vfs_write(p, buf, count, &p->f_pos);
1873 return tty_write(file, buf, count, ppos);
1876 static char ptychar[] = "pqrstuvwxyzabcde";
1879 * pty_line_name - generate name for a pty
1880 * @driver: the tty driver in use
1881 * @index: the minor number
1882 * @p: output buffer of at least 6 bytes
1884 * Generate a name from a driver reference and write it to the output
1889 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1891 int i = index + driver->name_base;
1892 /* ->name is initialized to "ttyp", but "tty" is expected */
1893 sprintf(p, "%s%c%x",
1894 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1895 ptychar[i >> 4 & 0xf], i & 0xf);
1899 * pty_line_name - generate name for a tty
1900 * @driver: the tty driver in use
1901 * @index: the minor number
1902 * @p: output buffer of at least 7 bytes
1904 * Generate a name from a driver reference and write it to the output
1909 static void tty_line_name(struct tty_driver *driver, int index, char *p)
1911 sprintf(p, "%s%d", driver->name, index + driver->name_base);
1915 * init_dev - initialise a tty device
1916 * @driver: tty driver we are opening a device on
1917 * @idx: device index
1918 * @tty: returned tty structure
1920 * Prepare a tty device. This may not be a "new" clean device but
1921 * could also be an active device. The pty drivers require special
1922 * handling because of this.
1925 * The function is called under the tty_mutex, which
1926 * protects us from the tty struct or driver itself going away.
1928 * On exit the tty device has the line discipline attached and
1929 * a reference count of 1. If a pair was created for pty/tty use
1930 * and the other was a pty master then it too has a reference count of 1.
1932 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1933 * failed open. The new code protects the open with a mutex, so it's
1934 * really quite straightforward. The mutex locking can probably be
1935 * relaxed for the (most common) case of reopening a tty.
1938 static int init_dev(struct tty_driver *driver, int idx,
1939 struct tty_struct **ret_tty)
1941 struct tty_struct *tty, *o_tty;
1942 struct ktermios *tp, **tp_loc, *o_tp, **o_tp_loc;
1943 struct ktermios *ltp, **ltp_loc, *o_ltp, **o_ltp_loc;
1946 /* check whether we're reopening an existing tty */
1947 if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
1948 tty = devpts_get_tty(idx);
1950 * If we don't have a tty here on a slave open, it's because
1951 * the master already started the close process and there's
1952 * no relation between devpts file and tty anymore.
1954 if (!tty && driver->subtype == PTY_TYPE_SLAVE) {
1959 * It's safe from now on because init_dev() is called with
1960 * tty_mutex held and release_dev() won't change tty->count
1961 * or tty->flags without having to grab tty_mutex
1963 if (tty && driver->subtype == PTY_TYPE_MASTER)
1966 tty = driver->ttys[idx];
1968 if (tty) goto fast_track;
1971 * First time open is complex, especially for PTY devices.
1972 * This code guarantees that either everything succeeds and the
1973 * TTY is ready for operation, or else the table slots are vacated
1974 * and the allocated memory released. (Except that the termios
1975 * and locked termios may be retained.)
1978 if (!try_module_get(driver->owner)) {
1987 tty = alloc_tty_struct();
1990 initialize_tty_struct(tty);
1991 tty->driver = driver;
1993 tty_line_name(driver, idx, tty->name);
1995 if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
1996 tp_loc = &tty->termios;
1997 ltp_loc = &tty->termios_locked;
1999 tp_loc = &driver->termios[idx];
2000 ltp_loc = &driver->termios_locked[idx];
2004 tp = (struct ktermios *) kmalloc(sizeof(struct ktermios),
2008 *tp = driver->init_termios;
2012 ltp = (struct ktermios *) kmalloc(sizeof(struct ktermios),
2016 memset(ltp, 0, sizeof(struct ktermios));
2019 if (driver->type == TTY_DRIVER_TYPE_PTY) {
2020 o_tty = alloc_tty_struct();
2023 initialize_tty_struct(o_tty);
2024 o_tty->driver = driver->other;
2026 tty_line_name(driver->other, idx, o_tty->name);
2028 if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
2029 o_tp_loc = &o_tty->termios;
2030 o_ltp_loc = &o_tty->termios_locked;
2032 o_tp_loc = &driver->other->termios[idx];
2033 o_ltp_loc = &driver->other->termios_locked[idx];
2037 o_tp = (struct ktermios *)
2038 kmalloc(sizeof(struct ktermios), GFP_KERNEL);
2041 *o_tp = driver->other->init_termios;
2045 o_ltp = (struct ktermios *)
2046 kmalloc(sizeof(struct ktermios), GFP_KERNEL);
2049 memset(o_ltp, 0, sizeof(struct ktermios));
2053 * Everything allocated ... set up the o_tty structure.
2055 if (!(driver->other->flags & TTY_DRIVER_DEVPTS_MEM)) {
2056 driver->other->ttys[idx] = o_tty;
2062 o_tty->termios = *o_tp_loc;
2063 o_tty->termios_locked = *o_ltp_loc;
2064 driver->other->refcount++;
2065 if (driver->subtype == PTY_TYPE_MASTER)
2068 /* Establish the links in both directions */
2074 * All structures have been allocated, so now we install them.
2075 * Failures after this point use release_tty to clean up, so
2076 * there's no need to null out the local pointers.
2078 if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
2079 driver->ttys[idx] = tty;
2086 tty->termios = *tp_loc;
2087 tty->termios_locked = *ltp_loc;
2088 /* Compatibility until drivers always set this */
2089 tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
2090 tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
2095 * Structures all installed ... call the ldisc open routines.
2096 * If we fail here just call release_tty to clean up. No need
2097 * to decrement the use counts, as release_tty doesn't care.
2100 if (tty->ldisc.open) {
2101 retval = (tty->ldisc.open)(tty);
2103 goto release_mem_out;
2105 if (o_tty && o_tty->ldisc.open) {
2106 retval = (o_tty->ldisc.open)(o_tty);
2108 if (tty->ldisc.close)
2109 (tty->ldisc.close)(tty);
2110 goto release_mem_out;
2112 tty_ldisc_enable(o_tty);
2114 tty_ldisc_enable(tty);
2118 * This fast open can be used if the tty is already open.
2119 * No memory is allocated, and the only failures are from
2120 * attempting to open a closing tty or attempting multiple
2121 * opens on a pty master.
2124 if (test_bit(TTY_CLOSING, &tty->flags)) {
2128 if (driver->type == TTY_DRIVER_TYPE_PTY &&
2129 driver->subtype == PTY_TYPE_MASTER) {
2131 * special case for PTY masters: only one open permitted,
2132 * and the slave side open count is incremented as well.
2141 tty->driver = driver; /* N.B. why do this every time?? */
2144 if(!test_bit(TTY_LDISC, &tty->flags))
2145 printk(KERN_ERR "init_dev but no ldisc\n");
2149 /* All paths come through here to release the mutex */
2153 /* Release locally allocated memory ... nothing placed in slots */
2157 free_tty_struct(o_tty);
2160 free_tty_struct(tty);
2163 module_put(driver->owner);
2167 /* call the tty release_tty routine to clean out this slot */
2169 if (printk_ratelimit())
2170 printk(KERN_INFO "init_dev: ldisc open failed, "
2171 "clearing slot %d\n", idx);
2172 release_tty(tty, idx);
2177 * release_one_tty - release tty structure memory
2179 * Releases memory associated with a tty structure, and clears out the
2180 * driver table slots. This function is called when a device is no longer
2181 * in use. It also gets called when setup of a device fails.
2184 * tty_mutex - sometimes only
2185 * takes the file list lock internally when working on the list
2186 * of ttys that the driver keeps.
2187 * FIXME: should we require tty_mutex is held here ??
2189 static void release_one_tty(struct tty_struct *tty, int idx)
2191 int devpts = tty->driver->flags & TTY_DRIVER_DEVPTS_MEM;
2192 struct ktermios *tp;
2195 tty->driver->ttys[idx] = NULL;
2197 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
2200 tty->driver->termios[idx] = NULL;
2203 tp = tty->termios_locked;
2205 tty->driver->termios_locked[idx] = NULL;
2211 tty->driver->refcount--;
2214 list_del_init(&tty->tty_files);
2217 free_tty_struct(tty);
2221 * release_tty - release tty structure memory
2223 * Release both @tty and a possible linked partner (think pty pair),
2224 * and decrement the refcount of the backing module.
2227 * tty_mutex - sometimes only
2228 * takes the file list lock internally when working on the list
2229 * of ttys that the driver keeps.
2230 * FIXME: should we require tty_mutex is held here ??
2232 static void release_tty(struct tty_struct *tty, int idx)
2234 struct tty_driver *driver = tty->driver;
2237 release_one_tty(tty->link, idx);
2238 release_one_tty(tty, idx);
2239 module_put(driver->owner);
2243 * Even releasing the tty structures is a tricky business.. We have
2244 * to be very careful that the structures are all released at the
2245 * same time, as interrupts might otherwise get the wrong pointers.
2247 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
2248 * lead to double frees or releasing memory still in use.
2250 static void release_dev(struct file * filp)
2252 struct tty_struct *tty, *o_tty;
2253 int pty_master, tty_closing, o_tty_closing, do_sleep;
2257 unsigned long flags;
2259 tty = (struct tty_struct *)filp->private_data;
2260 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "release_dev"))
2263 check_tty_count(tty, "release_dev");
2265 tty_fasync(-1, filp, 0);
2268 pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2269 tty->driver->subtype == PTY_TYPE_MASTER);
2270 devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0;
2273 #ifdef TTY_PARANOIA_CHECK
2274 if (idx < 0 || idx >= tty->driver->num) {
2275 printk(KERN_DEBUG "release_dev: bad idx when trying to "
2276 "free (%s)\n", tty->name);
2279 if (!(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
2280 if (tty != tty->driver->ttys[idx]) {
2281 printk(KERN_DEBUG "release_dev: driver.table[%d] not tty "
2282 "for (%s)\n", idx, tty->name);
2285 if (tty->termios != tty->driver->termios[idx]) {
2286 printk(KERN_DEBUG "release_dev: driver.termios[%d] not termios "
2291 if (tty->termios_locked != tty->driver->termios_locked[idx]) {
2292 printk(KERN_DEBUG "release_dev: driver.termios_locked[%d] not "
2293 "termios_locked for (%s)\n",
2300 #ifdef TTY_DEBUG_HANGUP
2301 printk(KERN_DEBUG "release_dev of %s (tty count=%d)...",
2302 tty_name(tty, buf), tty->count);
2305 #ifdef TTY_PARANOIA_CHECK
2306 if (tty->driver->other &&
2307 !(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
2308 if (o_tty != tty->driver->other->ttys[idx]) {
2309 printk(KERN_DEBUG "release_dev: other->table[%d] "
2310 "not o_tty for (%s)\n",
2314 if (o_tty->termios != tty->driver->other->termios[idx]) {
2315 printk(KERN_DEBUG "release_dev: other->termios[%d] "
2316 "not o_termios for (%s)\n",
2320 if (o_tty->termios_locked !=
2321 tty->driver->other->termios_locked[idx]) {
2322 printk(KERN_DEBUG "release_dev: other->termios_locked["
2323 "%d] not o_termios_locked for (%s)\n",
2327 if (o_tty->link != tty) {
2328 printk(KERN_DEBUG "release_dev: bad pty pointers\n");
2333 if (tty->driver->close)
2334 tty->driver->close(tty, filp);
2337 * Sanity check: if tty->count is going to zero, there shouldn't be
2338 * any waiters on tty->read_wait or tty->write_wait. We test the
2339 * wait queues and kick everyone out _before_ actually starting to
2340 * close. This ensures that we won't block while releasing the tty
2343 * The test for the o_tty closing is necessary, since the master and
2344 * slave sides may close in any order. If the slave side closes out
2345 * first, its count will be one, since the master side holds an open.
2346 * Thus this test wouldn't be triggered at the time the slave closes,
2349 * Note that it's possible for the tty to be opened again while we're
2350 * flushing out waiters. By recalculating the closing flags before
2351 * each iteration we avoid any problems.
2354 /* Guard against races with tty->count changes elsewhere and
2355 opens on /dev/tty */
2357 mutex_lock(&tty_mutex);
2358 tty_closing = tty->count <= 1;
2359 o_tty_closing = o_tty &&
2360 (o_tty->count <= (pty_master ? 1 : 0));
2364 if (waitqueue_active(&tty->read_wait)) {
2365 wake_up(&tty->read_wait);
2368 if (waitqueue_active(&tty->write_wait)) {
2369 wake_up(&tty->write_wait);
2373 if (o_tty_closing) {
2374 if (waitqueue_active(&o_tty->read_wait)) {
2375 wake_up(&o_tty->read_wait);
2378 if (waitqueue_active(&o_tty->write_wait)) {
2379 wake_up(&o_tty->write_wait);
2386 printk(KERN_WARNING "release_dev: %s: read/write wait queue "
2387 "active!\n", tty_name(tty, buf));
2388 mutex_unlock(&tty_mutex);
2393 * The closing flags are now consistent with the open counts on
2394 * both sides, and we've completed the last operation that could
2395 * block, so it's safe to proceed with closing.
2398 if (--o_tty->count < 0) {
2399 printk(KERN_WARNING "release_dev: bad pty slave count "
2401 o_tty->count, tty_name(o_tty, buf));
2405 if (--tty->count < 0) {
2406 printk(KERN_WARNING "release_dev: bad tty->count (%d) for %s\n",
2407 tty->count, tty_name(tty, buf));
2412 * We've decremented tty->count, so we need to remove this file
2413 * descriptor off the tty->tty_files list; this serves two
2415 * - check_tty_count sees the correct number of file descriptors
2416 * associated with this tty.
2417 * - do_tty_hangup no longer sees this file descriptor as
2418 * something that needs to be handled for hangups.
2421 filp->private_data = NULL;
2424 * Perform some housekeeping before deciding whether to return.
2426 * Set the TTY_CLOSING flag if this was the last open. In the
2427 * case of a pty we may have to wait around for the other side
2428 * to close, and TTY_CLOSING makes sure we can't be reopened.
2431 set_bit(TTY_CLOSING, &tty->flags);
2433 set_bit(TTY_CLOSING, &o_tty->flags);
2436 * If _either_ side is closing, make sure there aren't any
2437 * processes that still think tty or o_tty is their controlling
2440 if (tty_closing || o_tty_closing) {
2441 read_lock(&tasklist_lock);
2442 session_clear_tty(tty->session);
2444 session_clear_tty(o_tty->session);
2445 read_unlock(&tasklist_lock);
2448 mutex_unlock(&tty_mutex);
2450 /* check whether both sides are closing ... */
2451 if (!tty_closing || (o_tty && !o_tty_closing))
2454 #ifdef TTY_DEBUG_HANGUP
2455 printk(KERN_DEBUG "freeing tty structure...");
2458 * Prevent flush_to_ldisc() from rescheduling the work for later. Then
2459 * kill any delayed work. As this is the final close it does not
2460 * race with the set_ldisc code path.
2462 clear_bit(TTY_LDISC, &tty->flags);
2463 cancel_delayed_work(&tty->buf.work);
2466 * Wait for ->hangup_work and ->buf.work handlers to terminate
2469 flush_scheduled_work();
2472 * Wait for any short term users (we know they are just driver
2473 * side waiters as the file is closing so user count on the file
2476 spin_lock_irqsave(&tty_ldisc_lock, flags);
2477 while(tty->ldisc.refcount)
2479 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
2480 wait_event(tty_ldisc_wait, tty->ldisc.refcount == 0);
2481 spin_lock_irqsave(&tty_ldisc_lock, flags);
2483 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
2485 * Shutdown the current line discipline, and reset it to N_TTY.
2486 * N.B. why reset ldisc when we're releasing the memory??
2488 * FIXME: this MUST get fixed for the new reflocking
2490 if (tty->ldisc.close)
2491 (tty->ldisc.close)(tty);
2492 tty_ldisc_put(tty->ldisc.num);
2495 * Switch the line discipline back
2497 tty_ldisc_assign(tty, tty_ldisc_get(N_TTY));
2498 tty_set_termios_ldisc(tty,N_TTY);
2500 /* FIXME: could o_tty be in setldisc here ? */
2501 clear_bit(TTY_LDISC, &o_tty->flags);
2502 if (o_tty->ldisc.close)
2503 (o_tty->ldisc.close)(o_tty);
2504 tty_ldisc_put(o_tty->ldisc.num);
2505 tty_ldisc_assign(o_tty, tty_ldisc_get(N_TTY));
2506 tty_set_termios_ldisc(o_tty,N_TTY);
2509 * The release_tty function takes care of the details of clearing
2510 * the slots and preserving the termios structure.
2512 release_tty(tty, idx);
2514 #ifdef CONFIG_UNIX98_PTYS
2515 /* Make this pty number available for reallocation */
2517 down(&allocated_ptys_lock);
2518 idr_remove(&allocated_ptys, idx);
2519 up(&allocated_ptys_lock);
2526 * tty_open - open a tty device
2527 * @inode: inode of device file
2528 * @filp: file pointer to tty
2530 * tty_open and tty_release keep up the tty count that contains the
2531 * number of opens done on a tty. We cannot use the inode-count, as
2532 * different inodes might point to the same tty.
2534 * Open-counting is needed for pty masters, as well as for keeping
2535 * track of serial lines: DTR is dropped when the last close happens.
2536 * (This is not done solely through tty->count, now. - Ted 1/27/92)
2538 * The termios state of a pty is reset on first open so that
2539 * settings don't persist across reuse.
2541 * Locking: tty_mutex protects tty, get_tty_driver and init_dev work.
2542 * tty->count should protect the rest.
2543 * ->siglock protects ->signal/->sighand
2546 static int tty_open(struct inode * inode, struct file * filp)
2548 struct tty_struct *tty;
2550 struct tty_driver *driver;
2552 dev_t device = inode->i_rdev;
2553 unsigned short saved_flags = filp->f_flags;
2555 nonseekable_open(inode, filp);
2558 noctty = filp->f_flags & O_NOCTTY;
2562 mutex_lock(&tty_mutex);
2564 if (device == MKDEV(TTYAUX_MAJOR,0)) {
2565 tty = get_current_tty();
2567 mutex_unlock(&tty_mutex);
2570 driver = tty->driver;
2572 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
2577 if (device == MKDEV(TTY_MAJOR,0)) {
2578 extern struct tty_driver *console_driver;
2579 driver = console_driver;
2585 if (device == MKDEV(TTYAUX_MAJOR,1)) {
2586 driver = console_device(&index);
2588 /* Don't let /dev/console block */
2589 filp->f_flags |= O_NONBLOCK;
2593 mutex_unlock(&tty_mutex);
2597 driver = get_tty_driver(device, &index);
2599 mutex_unlock(&tty_mutex);
2603 retval = init_dev(driver, index, &tty);
2604 mutex_unlock(&tty_mutex);
2608 filp->private_data = tty;
2609 file_move(filp, &tty->tty_files);
2610 check_tty_count(tty, "tty_open");
2611 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2612 tty->driver->subtype == PTY_TYPE_MASTER)
2614 #ifdef TTY_DEBUG_HANGUP
2615 printk(KERN_DEBUG "opening %s...", tty->name);
2618 if (tty->driver->open)
2619 retval = tty->driver->open(tty, filp);
2623 filp->f_flags = saved_flags;
2625 if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
2629 #ifdef TTY_DEBUG_HANGUP
2630 printk(KERN_DEBUG "error %d in opening %s...", retval,
2634 if (retval != -ERESTARTSYS)
2636 if (signal_pending(current))
2640 * Need to reset f_op in case a hangup happened.
2642 if (filp->f_op == &hung_up_tty_fops)
2643 filp->f_op = &tty_fops;
2647 mutex_lock(&tty_mutex);
2648 spin_lock_irq(¤t->sighand->siglock);
2650 current->signal->leader &&
2651 !current->signal->tty &&
2652 tty->session == NULL)
2653 __proc_set_tty(current, tty);
2654 spin_unlock_irq(¤t->sighand->siglock);
2655 mutex_unlock(&tty_mutex);
2659 #ifdef CONFIG_UNIX98_PTYS
2661 * ptmx_open - open a unix 98 pty master
2662 * @inode: inode of device file
2663 * @filp: file pointer to tty
2665 * Allocate a unix98 pty master device from the ptmx driver.
2667 * Locking: tty_mutex protects theinit_dev work. tty->count should
2669 * allocated_ptys_lock handles the list of free pty numbers
2672 static int ptmx_open(struct inode * inode, struct file * filp)
2674 struct tty_struct *tty;
2679 nonseekable_open(inode, filp);
2681 /* find a device that is not in use. */
2682 down(&allocated_ptys_lock);
2683 if (!idr_pre_get(&allocated_ptys, GFP_KERNEL)) {
2684 up(&allocated_ptys_lock);
2687 idr_ret = idr_get_new(&allocated_ptys, NULL, &index);
2689 up(&allocated_ptys_lock);
2690 if (idr_ret == -EAGAIN)
2694 if (index >= pty_limit) {
2695 idr_remove(&allocated_ptys, index);
2696 up(&allocated_ptys_lock);
2699 up(&allocated_ptys_lock);
2701 mutex_lock(&tty_mutex);
2702 retval = init_dev(ptm_driver, index, &tty);
2703 mutex_unlock(&tty_mutex);
2708 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
2709 filp->private_data = tty;
2710 file_move(filp, &tty->tty_files);
2713 if (devpts_pty_new(tty->link))
2716 check_tty_count(tty, "tty_open");
2717 retval = ptm_driver->open(tty, filp);
2724 down(&allocated_ptys_lock);
2725 idr_remove(&allocated_ptys, index);
2726 up(&allocated_ptys_lock);
2732 * tty_release - vfs callback for close
2733 * @inode: inode of tty
2734 * @filp: file pointer for handle to tty
2736 * Called the last time each file handle is closed that references
2737 * this tty. There may however be several such references.
2740 * Takes bkl. See release_dev
2743 static int tty_release(struct inode * inode, struct file * filp)
2752 * tty_poll - check tty status
2753 * @filp: file being polled
2754 * @wait: poll wait structures to update
2756 * Call the line discipline polling method to obtain the poll
2757 * status of the device.
2759 * Locking: locks called line discipline but ldisc poll method
2760 * may be re-entered freely by other callers.
2763 static unsigned int tty_poll(struct file * filp, poll_table * wait)
2765 struct tty_struct * tty;
2766 struct tty_ldisc *ld;
2769 tty = (struct tty_struct *)filp->private_data;
2770 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_poll"))
2773 ld = tty_ldisc_ref_wait(tty);
2775 ret = (ld->poll)(tty, filp, wait);
2776 tty_ldisc_deref(ld);
2780 static int tty_fasync(int fd, struct file * filp, int on)
2782 struct tty_struct * tty;
2785 tty = (struct tty_struct *)filp->private_data;
2786 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_fasync"))
2789 retval = fasync_helper(fd, filp, on, &tty->fasync);
2796 if (!waitqueue_active(&tty->read_wait))
2797 tty->minimum_to_wake = 1;
2800 type = PIDTYPE_PGID;
2802 pid = task_pid(current);
2805 retval = __f_setown(filp, pid, type, 0);
2809 if (!tty->fasync && !waitqueue_active(&tty->read_wait))
2810 tty->minimum_to_wake = N_TTY_BUF_SIZE;
2816 * tiocsti - fake input character
2817 * @tty: tty to fake input into
2818 * @p: pointer to character
2820 * Fake input to a tty device. Does the neccessary locking and
2823 * FIXME: does not honour flow control ??
2826 * Called functions take tty_ldisc_lock
2827 * current->signal->tty check is safe without locks
2829 * FIXME: may race normal receive processing
2832 static int tiocsti(struct tty_struct *tty, char __user *p)
2835 struct tty_ldisc *ld;
2837 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2839 if (get_user(ch, p))
2841 ld = tty_ldisc_ref_wait(tty);
2842 ld->receive_buf(tty, &ch, &mbz, 1);
2843 tty_ldisc_deref(ld);
2848 * tiocgwinsz - implement window query ioctl
2850 * @arg: user buffer for result
2852 * Copies the kernel idea of the window size into the user buffer.
2854 * Locking: tty->termios_mutex is taken to ensure the winsize data
2858 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user * arg)
2862 mutex_lock(&tty->termios_mutex);
2863 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2864 mutex_unlock(&tty->termios_mutex);
2866 return err ? -EFAULT: 0;
2870 * tiocswinsz - implement window size set ioctl
2872 * @arg: user buffer for result
2874 * Copies the user idea of the window size to the kernel. Traditionally
2875 * this is just advisory information but for the Linux console it
2876 * actually has driver level meaning and triggers a VC resize.
2879 * Called function use the console_sem is used to ensure we do
2880 * not try and resize the console twice at once.
2881 * The tty->termios_mutex is used to ensure we don't double
2882 * resize and get confused. Lock order - tty->termios_mutex before
2886 static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty,
2887 struct winsize __user * arg)
2889 struct winsize tmp_ws;
2891 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2894 mutex_lock(&tty->termios_mutex);
2895 if (!memcmp(&tmp_ws, &tty->winsize, sizeof(*arg)))
2899 if (tty->driver->type == TTY_DRIVER_TYPE_CONSOLE) {
2900 if (vc_lock_resize(tty->driver_data, tmp_ws.ws_col,
2902 mutex_unlock(&tty->termios_mutex);
2908 kill_pgrp(tty->pgrp, SIGWINCH, 1);
2909 if ((real_tty->pgrp != tty->pgrp) && real_tty->pgrp)
2910 kill_pgrp(real_tty->pgrp, SIGWINCH, 1);
2911 tty->winsize = tmp_ws;
2912 real_tty->winsize = tmp_ws;
2914 mutex_unlock(&tty->termios_mutex);
2919 * tioccons - allow admin to move logical console
2920 * @file: the file to become console
2922 * Allow the adminstrator to move the redirected console device
2924 * Locking: uses redirect_lock to guard the redirect information
2927 static int tioccons(struct file *file)
2929 if (!capable(CAP_SYS_ADMIN))
2931 if (file->f_op->write == redirected_tty_write) {
2933 spin_lock(&redirect_lock);
2936 spin_unlock(&redirect_lock);
2941 spin_lock(&redirect_lock);
2943 spin_unlock(&redirect_lock);
2948 spin_unlock(&redirect_lock);
2953 * fionbio - non blocking ioctl
2954 * @file: file to set blocking value
2955 * @p: user parameter
2957 * Historical tty interfaces had a blocking control ioctl before
2958 * the generic functionality existed. This piece of history is preserved
2959 * in the expected tty API of posix OS's.
2961 * Locking: none, the open fle handle ensures it won't go away.
2964 static int fionbio(struct file *file, int __user *p)
2968 if (get_user(nonblock, p))
2972 file->f_flags |= O_NONBLOCK;
2974 file->f_flags &= ~O_NONBLOCK;
2979 * tiocsctty - set controlling tty
2980 * @tty: tty structure
2981 * @arg: user argument
2983 * This ioctl is used to manage job control. It permits a session
2984 * leader to set this tty as the controlling tty for the session.
2987 * Takes tty_mutex() to protect tty instance
2988 * Takes tasklist_lock internally to walk sessions
2989 * Takes ->siglock() when updating signal->tty
2992 static int tiocsctty(struct tty_struct *tty, int arg)
2995 if (current->signal->leader && (task_session(current) == tty->session))
2998 mutex_lock(&tty_mutex);
3000 * The process must be a session leader and
3001 * not have a controlling tty already.
3003 if (!current->signal->leader || current->signal->tty) {
3010 * This tty is already the controlling
3011 * tty for another session group!
3013 if ((arg == 1) && capable(CAP_SYS_ADMIN)) {
3017 read_lock(&tasklist_lock);
3018 session_clear_tty(tty->session);
3019 read_unlock(&tasklist_lock);
3025 proc_set_tty(current, tty);
3027 mutex_unlock(&tty_mutex);
3032 * tiocgpgrp - get process group
3033 * @tty: tty passed by user
3034 * @real_tty: tty side of the tty pased by the user if a pty else the tty
3037 * Obtain the process group of the tty. If there is no process group
3040 * Locking: none. Reference to current->signal->tty is safe.
3043 static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
3046 * (tty == real_tty) is a cheap way of
3047 * testing if the tty is NOT a master pty.
3049 if (tty == real_tty && current->signal->tty != real_tty)
3051 return put_user(pid_nr(real_tty->pgrp), p);
3055 * tiocspgrp - attempt to set process group
3056 * @tty: tty passed by user
3057 * @real_tty: tty side device matching tty passed by user
3060 * Set the process group of the tty to the session passed. Only
3061 * permitted where the tty session is our session.
3066 static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
3070 int retval = tty_check_change(real_tty);
3076 if (!current->signal->tty ||
3077 (current->signal->tty != real_tty) ||
3078 (real_tty->session != task_session(current)))
3080 if (get_user(pgrp_nr, p))
3085 pgrp = find_pid(pgrp_nr);
3090 if (session_of_pgrp(pgrp) != task_session(current))
3093 put_pid(real_tty->pgrp);
3094 real_tty->pgrp = get_pid(pgrp);
3101 * tiocgsid - get session id
3102 * @tty: tty passed by user
3103 * @real_tty: tty side of the tty pased by the user if a pty else the tty
3104 * @p: pointer to returned session id
3106 * Obtain the session id of the tty. If there is no session
3109 * Locking: none. Reference to current->signal->tty is safe.
3112 static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
3115 * (tty == real_tty) is a cheap way of
3116 * testing if the tty is NOT a master pty.
3118 if (tty == real_tty && current->signal->tty != real_tty)
3120 if (!real_tty->session)
3122 return put_user(pid_nr(real_tty->session), p);
3126 * tiocsetd - set line discipline
3128 * @p: pointer to user data
3130 * Set the line discipline according to user request.
3132 * Locking: see tty_set_ldisc, this function is just a helper
3135 static int tiocsetd(struct tty_struct *tty, int __user *p)
3139 if (get_user(ldisc, p))
3141 return tty_set_ldisc(tty, ldisc);
3145 * send_break - performed time break
3146 * @tty: device to break on
3147 * @duration: timeout in mS
3149 * Perform a timed break on hardware that lacks its own driver level
3150 * timed break functionality.
3153 * atomic_write_lock serializes
3157 static int send_break(struct tty_struct *tty, unsigned int duration)
3159 if (mutex_lock_interruptible(&tty->atomic_write_lock))
3161 tty->driver->break_ctl(tty, -1);
3162 if (!signal_pending(current)) {
3163 msleep_interruptible(duration);
3165 tty->driver->break_ctl(tty, 0);
3166 mutex_unlock(&tty->atomic_write_lock);
3167 if (signal_pending(current))
3173 * tiocmget - get modem status
3175 * @file: user file pointer
3176 * @p: pointer to result
3178 * Obtain the modem status bits from the tty driver if the feature
3179 * is supported. Return -EINVAL if it is not available.
3181 * Locking: none (up to the driver)
3184 static int tty_tiocmget(struct tty_struct *tty, struct file *file, int __user *p)
3186 int retval = -EINVAL;
3188 if (tty->driver->tiocmget) {
3189 retval = tty->driver->tiocmget(tty, file);
3192 retval = put_user(retval, p);
3198 * tiocmset - set modem status
3200 * @file: user file pointer
3201 * @cmd: command - clear bits, set bits or set all
3202 * @p: pointer to desired bits
3204 * Set the modem status bits from the tty driver if the feature
3205 * is supported. Return -EINVAL if it is not available.
3207 * Locking: none (up to the driver)
3210 static int tty_tiocmset(struct tty_struct *tty, struct file *file, unsigned int cmd,
3213 int retval = -EINVAL;
3215 if (tty->driver->tiocmset) {
3216 unsigned int set, clear, val;
3218 retval = get_user(val, p);
3236 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
3237 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
3239 retval = tty->driver->tiocmset(tty, file, set, clear);
3245 * Split this up, as gcc can choke on it otherwise..
3247 int tty_ioctl(struct inode * inode, struct file * file,
3248 unsigned int cmd, unsigned long arg)
3250 struct tty_struct *tty, *real_tty;
3251 void __user *p = (void __user *)arg;
3253 struct tty_ldisc *ld;
3255 tty = (struct tty_struct *)file->private_data;
3256 if (tty_paranoia_check(tty, inode, "tty_ioctl"))
3259 /* CHECKME: is this safe as one end closes ? */
3262 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
3263 tty->driver->subtype == PTY_TYPE_MASTER)
3264 real_tty = tty->link;
3267 * Break handling by driver
3269 if (!tty->driver->break_ctl) {
3273 if (tty->driver->ioctl)
3274 return tty->driver->ioctl(tty, file, cmd, arg);
3277 /* These two ioctl's always return success; even if */
3278 /* the driver doesn't support them. */
3281 if (!tty->driver->ioctl)
3283 retval = tty->driver->ioctl(tty, file, cmd, arg);
3284 if (retval == -ENOIOCTLCMD)
3291 * Factor out some common prep work
3299 retval = tty_check_change(tty);
3302 if (cmd != TIOCCBRK) {
3303 tty_wait_until_sent(tty, 0);
3304 if (signal_pending(current))
3312 return tiocsti(tty, p);
3314 return tiocgwinsz(tty, p);
3316 return tiocswinsz(tty, real_tty, p);
3318 return real_tty!=tty ? -EINVAL : tioccons(file);
3320 return fionbio(file, p);
3322 set_bit(TTY_EXCLUSIVE, &tty->flags);
3325 clear_bit(TTY_EXCLUSIVE, &tty->flags);
3328 if (current->signal->tty != tty)
3333 return tiocsctty(tty, arg);
3335 return tiocgpgrp(tty, real_tty, p);
3337 return tiocspgrp(tty, real_tty, p);
3339 return tiocgsid(tty, real_tty, p);
3341 /* FIXME: check this is ok */
3342 return put_user(tty->ldisc.num, (int __user *)p);
3344 return tiocsetd(tty, p);
3347 return tioclinux(tty, arg);
3352 case TIOCSBRK: /* Turn break on, unconditionally */
3353 tty->driver->break_ctl(tty, -1);
3356 case TIOCCBRK: /* Turn break off, unconditionally */
3357 tty->driver->break_ctl(tty, 0);
3359 case TCSBRK: /* SVID version: non-zero arg --> no break */
3360 /* non-zero arg means wait for all output data
3361 * to be sent (performed above) but don't send break.
3362 * This is used by the tcdrain() termios function.
3365 return send_break(tty, 250);
3367 case TCSBRKP: /* support for POSIX tcsendbreak() */
3368 return send_break(tty, arg ? arg*100 : 250);
3371 return tty_tiocmget(tty, file, p);
3376 return tty_tiocmset(tty, file, cmd, p);
3381 /* flush tty buffer and allow ldisc to process ioctl */
3382 tty_buffer_flush(tty);
3387 if (tty->driver->ioctl) {
3388 retval = (tty->driver->ioctl)(tty, file, cmd, arg);
3389 if (retval != -ENOIOCTLCMD)
3392 ld = tty_ldisc_ref_wait(tty);
3395 retval = ld->ioctl(tty, file, cmd, arg);
3396 if (retval == -ENOIOCTLCMD)
3399 tty_ldisc_deref(ld);
3403 #ifdef CONFIG_COMPAT
3404 static long tty_compat_ioctl(struct file * file, unsigned int cmd,
3407 struct inode *inode = file->f_dentry->d_inode;
3408 struct tty_struct *tty = file->private_data;
3409 struct tty_ldisc *ld;
3410 int retval = -ENOIOCTLCMD;
3412 if (tty_paranoia_check(tty, inode, "tty_ioctl"))
3415 if (tty->driver->compat_ioctl) {
3416 retval = (tty->driver->compat_ioctl)(tty, file, cmd, arg);
3417 if (retval != -ENOIOCTLCMD)
3421 ld = tty_ldisc_ref_wait(tty);
3422 if (ld->compat_ioctl)
3423 retval = ld->compat_ioctl(tty, file, cmd, arg);
3424 tty_ldisc_deref(ld);
3431 * This implements the "Secure Attention Key" --- the idea is to
3432 * prevent trojan horses by killing all processes associated with this
3433 * tty when the user hits the "Secure Attention Key". Required for
3434 * super-paranoid applications --- see the Orange Book for more details.
3436 * This code could be nicer; ideally it should send a HUP, wait a few
3437 * seconds, then send a INT, and then a KILL signal. But you then
3438 * have to coordinate with the init process, since all processes associated
3439 * with the current tty must be dead before the new getty is allowed
3442 * Now, if it would be correct ;-/ The current code has a nasty hole -
3443 * it doesn't catch files in flight. We may send the descriptor to ourselves
3444 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
3446 * Nasty bug: do_SAK is being called in interrupt context. This can
3447 * deadlock. We punt it up to process context. AKPM - 16Mar2001
3449 void __do_SAK(struct tty_struct *tty)
3454 struct task_struct *g, *p;
3455 struct pid *session;
3458 struct fdtable *fdt;
3462 session = tty->session;
3464 tty_ldisc_flush(tty);
3466 if (tty->driver->flush_buffer)
3467 tty->driver->flush_buffer(tty);
3469 read_lock(&tasklist_lock);
3470 /* Kill the entire session */
3471 do_each_pid_task(session, PIDTYPE_SID, p) {
3472 printk(KERN_NOTICE "SAK: killed process %d"
3473 " (%s): process_session(p)==tty->session\n",
3475 send_sig(SIGKILL, p, 1);
3476 } while_each_pid_task(session, PIDTYPE_SID, p);
3477 /* Now kill any processes that happen to have the
3480 do_each_thread(g, p) {
3481 if (p->signal->tty == tty) {
3482 printk(KERN_NOTICE "SAK: killed process %d"
3483 " (%s): process_session(p)==tty->session\n",
3485 send_sig(SIGKILL, p, 1);
3491 * We don't take a ref to the file, so we must
3492 * hold ->file_lock instead.
3494 spin_lock(&p->files->file_lock);
3495 fdt = files_fdtable(p->files);
3496 for (i=0; i < fdt->max_fds; i++) {
3497 filp = fcheck_files(p->files, i);
3500 if (filp->f_op->read == tty_read &&
3501 filp->private_data == tty) {
3502 printk(KERN_NOTICE "SAK: killed process %d"
3503 " (%s): fd#%d opened to the tty\n",
3504 p->pid, p->comm, i);
3505 force_sig(SIGKILL, p);
3509 spin_unlock(&p->files->file_lock);
3512 } while_each_thread(g, p);
3513 read_unlock(&tasklist_lock);
3517 static void do_SAK_work(struct work_struct *work)
3519 struct tty_struct *tty =
3520 container_of(work, struct tty_struct, SAK_work);
3525 * The tq handling here is a little racy - tty->SAK_work may already be queued.
3526 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
3527 * the values which we write to it will be identical to the values which it
3528 * already has. --akpm
3530 void do_SAK(struct tty_struct *tty)
3534 schedule_work(&tty->SAK_work);
3537 EXPORT_SYMBOL(do_SAK);
3541 * @work: tty structure passed from work queue.
3543 * This routine is called out of the software interrupt to flush data
3544 * from the buffer chain to the line discipline.
3546 * Locking: holds tty->buf.lock to guard buffer list. Drops the lock
3547 * while invoking the line discipline receive_buf method. The
3548 * receive_buf method is single threaded for each tty instance.
3551 static void flush_to_ldisc(struct work_struct *work)
3553 struct tty_struct *tty =
3554 container_of(work, struct tty_struct, buf.work.work);
3555 unsigned long flags;
3556 struct tty_ldisc *disc;
3557 struct tty_buffer *tbuf, *head;
3559 unsigned char *flag_buf;
3561 disc = tty_ldisc_ref(tty);
3562 if (disc == NULL) /* !TTY_LDISC */
3565 spin_lock_irqsave(&tty->buf.lock, flags);
3566 head = tty->buf.head;
3568 tty->buf.head = NULL;
3570 int count = head->commit - head->read;
3572 if (head->next == NULL)
3576 tty_buffer_free(tty, tbuf);
3579 if (!tty->receive_room) {
3580 schedule_delayed_work(&tty->buf.work, 1);
3583 if (count > tty->receive_room)
3584 count = tty->receive_room;
3585 char_buf = head->char_buf_ptr + head->read;
3586 flag_buf = head->flag_buf_ptr + head->read;
3587 head->read += count;
3588 spin_unlock_irqrestore(&tty->buf.lock, flags);
3589 disc->receive_buf(tty, char_buf, flag_buf, count);
3590 spin_lock_irqsave(&tty->buf.lock, flags);
3592 tty->buf.head = head;
3594 spin_unlock_irqrestore(&tty->buf.lock, flags);
3596 tty_ldisc_deref(disc);
3600 * tty_flip_buffer_push - terminal
3603 * Queue a push of the terminal flip buffers to the line discipline. This
3604 * function must not be called from IRQ context if tty->low_latency is set.
3606 * In the event of the queue being busy for flipping the work will be
3607 * held off and retried later.
3609 * Locking: tty buffer lock. Driver locks in low latency mode.
3612 void tty_flip_buffer_push(struct tty_struct *tty)
3614 unsigned long flags;
3615 spin_lock_irqsave(&tty->buf.lock, flags);
3616 if (tty->buf.tail != NULL)
3617 tty->buf.tail->commit = tty->buf.tail->used;
3618 spin_unlock_irqrestore(&tty->buf.lock, flags);
3620 if (tty->low_latency)
3621 flush_to_ldisc(&tty->buf.work.work);
3623 schedule_delayed_work(&tty->buf.work, 1);
3626 EXPORT_SYMBOL(tty_flip_buffer_push);
3630 * initialize_tty_struct
3631 * @tty: tty to initialize
3633 * This subroutine initializes a tty structure that has been newly
3636 * Locking: none - tty in question must not be exposed at this point
3639 static void initialize_tty_struct(struct tty_struct *tty)
3641 memset(tty, 0, sizeof(struct tty_struct));
3642 tty->magic = TTY_MAGIC;
3643 tty_ldisc_assign(tty, tty_ldisc_get(N_TTY));
3644 tty->session = NULL;
3646 tty->overrun_time = jiffies;
3647 tty->buf.head = tty->buf.tail = NULL;
3648 tty_buffer_init(tty);
3649 INIT_DELAYED_WORK(&tty->buf.work, flush_to_ldisc);
3650 init_MUTEX(&tty->buf.pty_sem);
3651 mutex_init(&tty->termios_mutex);
3652 init_waitqueue_head(&tty->write_wait);
3653 init_waitqueue_head(&tty->read_wait);
3654 INIT_WORK(&tty->hangup_work, do_tty_hangup);
3655 mutex_init(&tty->atomic_read_lock);
3656 mutex_init(&tty->atomic_write_lock);
3657 spin_lock_init(&tty->read_lock);
3658 INIT_LIST_HEAD(&tty->tty_files);
3659 INIT_WORK(&tty->SAK_work, do_SAK_work);
3663 * The default put_char routine if the driver did not define one.
3666 static void tty_default_put_char(struct tty_struct *tty, unsigned char ch)
3668 tty->driver->write(tty, &ch, 1);
3671 static struct class *tty_class;
3674 * tty_register_device - register a tty device
3675 * @driver: the tty driver that describes the tty device
3676 * @index: the index in the tty driver for this tty device
3677 * @device: a struct device that is associated with this tty device.
3678 * This field is optional, if there is no known struct device
3679 * for this tty device it can be set to NULL safely.
3681 * Returns a pointer to the struct device for this tty device
3682 * (or ERR_PTR(-EFOO) on error).
3684 * This call is required to be made to register an individual tty device
3685 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3686 * that bit is not set, this function should not be called by a tty
3692 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
3693 struct device *device)
3696 dev_t dev = MKDEV(driver->major, driver->minor_start) + index;
3698 if (index >= driver->num) {
3699 printk(KERN_ERR "Attempt to register invalid tty line number "
3701 return ERR_PTR(-EINVAL);
3704 if (driver->type == TTY_DRIVER_TYPE_PTY)
3705 pty_line_name(driver, index, name);
3707 tty_line_name(driver, index, name);
3709 return device_create(tty_class, device, dev, name);
3713 * tty_unregister_device - unregister a tty device
3714 * @driver: the tty driver that describes the tty device
3715 * @index: the index in the tty driver for this tty device
3717 * If a tty device is registered with a call to tty_register_device() then
3718 * this function must be called when the tty device is gone.
3723 void tty_unregister_device(struct tty_driver *driver, unsigned index)
3725 device_destroy(tty_class, MKDEV(driver->major, driver->minor_start) + index);
3728 EXPORT_SYMBOL(tty_register_device);
3729 EXPORT_SYMBOL(tty_unregister_device);
3731 struct tty_driver *alloc_tty_driver(int lines)
3733 struct tty_driver *driver;
3735 driver = kmalloc(sizeof(struct tty_driver), GFP_KERNEL);
3737 memset(driver, 0, sizeof(struct tty_driver));
3738 driver->magic = TTY_DRIVER_MAGIC;
3739 driver->num = lines;
3740 /* later we'll move allocation of tables here */
3745 void put_tty_driver(struct tty_driver *driver)
3750 void tty_set_operations(struct tty_driver *driver,
3751 const struct tty_operations *op)
3753 driver->open = op->open;
3754 driver->close = op->close;
3755 driver->write = op->write;
3756 driver->put_char = op->put_char;
3757 driver->flush_chars = op->flush_chars;
3758 driver->write_room = op->write_room;
3759 driver->chars_in_buffer = op->chars_in_buffer;
3760 driver->ioctl = op->ioctl;
3761 driver->compat_ioctl = op->compat_ioctl;
3762 driver->set_termios = op->set_termios;
3763 driver->throttle = op->throttle;
3764 driver->unthrottle = op->unthrottle;
3765 driver->stop = op->stop;
3766 driver->start = op->start;
3767 driver->hangup = op->hangup;
3768 driver->break_ctl = op->break_ctl;
3769 driver->flush_buffer = op->flush_buffer;
3770 driver->set_ldisc = op->set_ldisc;
3771 driver->wait_until_sent = op->wait_until_sent;
3772 driver->send_xchar = op->send_xchar;
3773 driver->read_proc = op->read_proc;
3774 driver->write_proc = op->write_proc;
3775 driver->tiocmget = op->tiocmget;
3776 driver->tiocmset = op->tiocmset;
3780 EXPORT_SYMBOL(alloc_tty_driver);
3781 EXPORT_SYMBOL(put_tty_driver);
3782 EXPORT_SYMBOL(tty_set_operations);
3785 * Called by a tty driver to register itself.
3787 int tty_register_driver(struct tty_driver *driver)
3794 if (driver->flags & TTY_DRIVER_INSTALLED)
3797 if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM) && driver->num) {
3798 p = kzalloc(driver->num * 3 * sizeof(void *), GFP_KERNEL);
3803 if (!driver->major) {
3804 error = alloc_chrdev_region(&dev, driver->minor_start, driver->num,
3807 driver->major = MAJOR(dev);
3808 driver->minor_start = MINOR(dev);
3811 dev = MKDEV(driver->major, driver->minor_start);
3812 error = register_chrdev_region(dev, driver->num, driver->name);
3820 driver->ttys = (struct tty_struct **)p;
3821 driver->termios = (struct ktermios **)(p + driver->num);
3822 driver->termios_locked = (struct ktermios **)(p + driver->num * 2);
3824 driver->ttys = NULL;
3825 driver->termios = NULL;
3826 driver->termios_locked = NULL;
3829 cdev_init(&driver->cdev, &tty_fops);
3830 driver->cdev.owner = driver->owner;
3831 error = cdev_add(&driver->cdev, dev, driver->num);
3833 unregister_chrdev_region(dev, driver->num);
3834 driver->ttys = NULL;
3835 driver->termios = driver->termios_locked = NULL;
3840 if (!driver->put_char)
3841 driver->put_char = tty_default_put_char;
3843 mutex_lock(&tty_mutex);
3844 list_add(&driver->tty_drivers, &tty_drivers);
3845 mutex_unlock(&tty_mutex);
3847 if ( !(driver->flags & TTY_DRIVER_DYNAMIC_DEV) ) {
3848 for(i = 0; i < driver->num; i++)
3849 tty_register_device(driver, i, NULL);
3851 proc_tty_register_driver(driver);
3855 EXPORT_SYMBOL(tty_register_driver);
3858 * Called by a tty driver to unregister itself.
3860 int tty_unregister_driver(struct tty_driver *driver)
3863 struct ktermios *tp;
3866 if (driver->refcount)
3869 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3871 mutex_lock(&tty_mutex);
3872 list_del(&driver->tty_drivers);
3873 mutex_unlock(&tty_mutex);
3876 * Free the termios and termios_locked structures because
3877 * we don't want to get memory leaks when modular tty
3878 * drivers are removed from the kernel.
3880 for (i = 0; i < driver->num; i++) {
3881 tp = driver->termios[i];
3883 driver->termios[i] = NULL;
3886 tp = driver->termios_locked[i];
3888 driver->termios_locked[i] = NULL;
3891 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3892 tty_unregister_device(driver, i);
3895 proc_tty_unregister_driver(driver);
3896 driver->ttys = NULL;
3897 driver->termios = driver->termios_locked = NULL;
3899 cdev_del(&driver->cdev);
3902 EXPORT_SYMBOL(tty_unregister_driver);
3904 dev_t tty_devnum(struct tty_struct *tty)
3906 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3908 EXPORT_SYMBOL(tty_devnum);
3910 void proc_clear_tty(struct task_struct *p)
3912 spin_lock_irq(&p->sighand->siglock);
3913 p->signal->tty = NULL;
3914 spin_unlock_irq(&p->sighand->siglock);
3916 EXPORT_SYMBOL(proc_clear_tty);
3918 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3921 /* We should not have a session or pgrp to here but.... */
3922 put_pid(tty->session);
3924 tty->session = get_pid(task_session(tsk));
3925 tty->pgrp = get_pid(task_pgrp(tsk));
3927 put_pid(tsk->signal->tty_old_pgrp);
3928 tsk->signal->tty = tty;
3929 tsk->signal->tty_old_pgrp = NULL;
3932 static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3934 spin_lock_irq(&tsk->sighand->siglock);
3935 __proc_set_tty(tsk, tty);
3936 spin_unlock_irq(&tsk->sighand->siglock);
3939 struct tty_struct *get_current_tty(void)
3941 struct tty_struct *tty;
3942 WARN_ON_ONCE(!mutex_is_locked(&tty_mutex));
3943 tty = current->signal->tty;
3945 * session->tty can be changed/cleared from under us, make sure we
3946 * issue the load. The obtained pointer, when not NULL, is valid as
3947 * long as we hold tty_mutex.
3952 EXPORT_SYMBOL_GPL(get_current_tty);
3955 * Initialize the console device. This is called *early*, so
3956 * we can't necessarily depend on lots of kernel help here.
3957 * Just do some early initializations, and do the complex setup
3960 void __init console_init(void)
3964 /* Setup the default TTY line discipline. */
3965 (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY);
3968 * set up the console device so that later boot sequences can
3969 * inform about problems etc..
3971 call = __con_initcall_start;
3972 while (call < __con_initcall_end) {
3979 extern int vty_init(void);
3982 static int __init tty_class_init(void)
3984 tty_class = class_create(THIS_MODULE, "tty");
3985 if (IS_ERR(tty_class))
3986 return PTR_ERR(tty_class);
3990 postcore_initcall(tty_class_init);
3992 /* 3/2004 jmc: why do these devices exist? */
3994 static struct cdev tty_cdev, console_cdev;
3995 #ifdef CONFIG_UNIX98_PTYS
3996 static struct cdev ptmx_cdev;
3999 static struct cdev vc0_cdev;
4003 * Ok, now we can initialize the rest of the tty devices and can count
4004 * on memory allocations, interrupts etc..
4006 static int __init tty_init(void)
4008 cdev_init(&tty_cdev, &tty_fops);
4009 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
4010 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
4011 panic("Couldn't register /dev/tty driver\n");
4012 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), "tty");
4014 cdev_init(&console_cdev, &console_fops);
4015 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
4016 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
4017 panic("Couldn't register /dev/console driver\n");
4018 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 1), "console");
4020 #ifdef CONFIG_UNIX98_PTYS
4021 cdev_init(&ptmx_cdev, &ptmx_fops);
4022 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
4023 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
4024 panic("Couldn't register /dev/ptmx driver\n");
4025 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), "ptmx");
4029 cdev_init(&vc0_cdev, &console_fops);
4030 if (cdev_add(&vc0_cdev, MKDEV(TTY_MAJOR, 0), 1) ||
4031 register_chrdev_region(MKDEV(TTY_MAJOR, 0), 1, "/dev/vc/0") < 0)
4032 panic("Couldn't register /dev/tty0 driver\n");
4033 device_create(tty_class, NULL, MKDEV(TTY_MAJOR, 0), "tty0");
4039 module_init(tty_init);