2 * linux/drivers/char/tty_io.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
8 * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles
9 * or rs-channels. It also implements echoing, cooked mode etc.
11 * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.
13 * Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the
14 * tty_struct and tty_queue structures. Previously there was an array
15 * of 256 tty_struct's which was statically allocated, and the
16 * tty_queue structures were allocated at boot time. Both are now
17 * dynamically allocated only when the tty is open.
19 * Also restructured routines so that there is more of a separation
20 * between the high-level tty routines (tty_io.c and tty_ioctl.c) and
21 * the low-level tty routines (serial.c, pty.c, console.c). This
22 * makes for cleaner and more compact code. -TYT, 9/17/92
24 * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
25 * which can be dynamically activated and de-activated by the line
26 * discipline handling modules (like SLIP).
28 * NOTE: pay no attention to the line discipline code (yet); its
29 * interface is still subject to change in this version...
32 * Added functionality to the OPOST tty handling. No delays, but all
33 * other bits should be there.
34 * -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993.
36 * Rewrote canonical mode and added more termios flags.
37 * -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94
39 * Reorganized FASYNC support so mouse code can share it.
40 * -- ctm@ardi.com, 9Sep95
42 * New TIOCLINUX variants added.
43 * -- mj@k332.feld.cvut.cz, 19-Nov-95
45 * Restrict vt switching via ioctl()
46 * -- grif@cs.ucr.edu, 5-Dec-95
48 * Move console and virtual terminal code to more appropriate files,
49 * implement CONFIG_VT and generalize console device interface.
50 * -- Marko Kohtala <Marko.Kohtala@hut.fi>, March 97
52 * Rewrote init_dev and release_dev to eliminate races.
53 * -- Bill Hawes <whawes@star.net>, June 97
55 * Added devfs support.
56 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 13-Jan-1998
58 * Added support for a Unix98-style ptmx device.
59 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
61 * Reduced memory usage for older ARM systems
62 * -- Russell King <rmk@arm.linux.org.uk>
64 * Move do_SAK() into process context. Less stack use in devfs functions.
65 * alloc_tty_struct() always uses kmalloc() -- Andrew Morton <andrewm@uow.edu.eu> 17Mar01
68 #include <linux/types.h>
69 #include <linux/major.h>
70 #include <linux/errno.h>
71 #include <linux/signal.h>
72 #include <linux/fcntl.h>
73 #include <linux/sched.h>
74 #include <linux/interrupt.h>
75 #include <linux/tty.h>
76 #include <linux/tty_driver.h>
77 #include <linux/tty_flip.h>
78 #include <linux/devpts_fs.h>
79 #include <linux/file.h>
80 #include <linux/console.h>
81 #include <linux/timer.h>
82 #include <linux/ctype.h>
85 #include <linux/string.h>
86 #include <linux/slab.h>
87 #include <linux/poll.h>
88 #include <linux/proc_fs.h>
89 #include <linux/init.h>
90 #include <linux/module.h>
91 #include <linux/smp_lock.h>
92 #include <linux/device.h>
93 #include <linux/idr.h>
94 #include <linux/wait.h>
95 #include <linux/bitops.h>
96 #include <linux/delay.h>
98 #include <asm/uaccess.h>
99 #include <asm/system.h>
101 #include <linux/kbd_kern.h>
102 #include <linux/vt_kern.h>
103 #include <linux/selection.h>
105 #include <linux/kmod.h>
107 #undef TTY_DEBUG_HANGUP
109 #define TTY_PARANOIA_CHECK 1
110 #define CHECK_TTY_COUNT 1
112 struct ktermios tty_std_termios = { /* for the benefit of tty drivers */
113 .c_iflag = ICRNL | IXON,
114 .c_oflag = OPOST | ONLCR,
115 .c_cflag = B38400 | CS8 | CREAD | HUPCL,
116 .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
117 ECHOCTL | ECHOKE | IEXTEN,
123 EXPORT_SYMBOL(tty_std_termios);
125 /* This list gets poked at by procfs and various bits of boot up code. This
126 could do with some rationalisation such as pulling the tty proc function
129 LIST_HEAD(tty_drivers); /* linked list of tty drivers */
131 /* Mutex to protect creating and releasing a tty. This is shared with
132 vt.c for deeply disgusting hack reasons */
133 DEFINE_MUTEX(tty_mutex);
134 EXPORT_SYMBOL(tty_mutex);
136 #ifdef CONFIG_UNIX98_PTYS
137 extern struct tty_driver *ptm_driver; /* Unix98 pty masters; for /dev/ptmx */
138 extern int pty_limit; /* Config limit on Unix98 ptys */
139 static DEFINE_IDR(allocated_ptys);
140 static DECLARE_MUTEX(allocated_ptys_lock);
141 static int ptmx_open(struct inode *, struct file *);
144 extern void disable_early_printk(void);
146 static void initialize_tty_struct(struct tty_struct *tty);
148 static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
149 static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
150 ssize_t redirected_tty_write(struct file *, const char __user *, size_t, loff_t *);
151 static unsigned int tty_poll(struct file *, poll_table *);
152 static int tty_open(struct inode *, struct file *);
153 static int tty_release(struct inode *, struct file *);
154 int tty_ioctl(struct inode * inode, struct file * file,
155 unsigned int cmd, unsigned long arg);
156 static int tty_fasync(int fd, struct file * filp, int on);
157 static void release_mem(struct tty_struct *tty, int idx);
160 * alloc_tty_struct - allocate a tty object
162 * Return a new empty tty structure. The data fields have not
163 * been initialized in any way but has been zeroed
168 static struct tty_struct *alloc_tty_struct(void)
170 return kzalloc(sizeof(struct tty_struct), GFP_KERNEL);
173 static void tty_buffer_free_all(struct tty_struct *);
176 * free_tty_struct - free a disused tty
177 * @tty: tty struct to free
179 * Free the write buffers, tty queue and tty memory itself.
181 * Locking: none. Must be called after tty is definitely unused
184 static inline void free_tty_struct(struct tty_struct *tty)
186 kfree(tty->write_buf);
187 tty_buffer_free_all(tty);
191 #define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base)
194 * tty_name - return tty naming
195 * @tty: tty structure
196 * @buf: buffer for output
198 * Convert a tty structure into a name. The name reflects the kernel
199 * naming policy and if udev is in use may not reflect user space
204 char *tty_name(struct tty_struct *tty, char *buf)
206 if (!tty) /* Hmm. NULL pointer. That's fun. */
207 strcpy(buf, "NULL tty");
209 strcpy(buf, tty->name);
213 EXPORT_SYMBOL(tty_name);
215 int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
218 #ifdef TTY_PARANOIA_CHECK
221 "null TTY for (%d:%d) in %s\n",
222 imajor(inode), iminor(inode), routine);
225 if (tty->magic != TTY_MAGIC) {
227 "bad magic number for tty struct (%d:%d) in %s\n",
228 imajor(inode), iminor(inode), routine);
235 static int check_tty_count(struct tty_struct *tty, const char *routine)
237 #ifdef CHECK_TTY_COUNT
242 list_for_each(p, &tty->tty_files) {
246 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
247 tty->driver->subtype == PTY_TYPE_SLAVE &&
248 tty->link && tty->link->count)
250 if (tty->count != count) {
251 printk(KERN_WARNING "Warning: dev (%s) tty->count(%d) "
252 "!= #fd's(%d) in %s\n",
253 tty->name, tty->count, count, routine);
261 * Tty buffer allocation management
265 * tty_buffer_free_all - free buffers used by a tty
266 * @tty: tty to free from
268 * Remove all the buffers pending on a tty whether queued with data
269 * or in the free ring. Must be called when the tty is no longer in use
274 static void tty_buffer_free_all(struct tty_struct *tty)
276 struct tty_buffer *thead;
277 while((thead = tty->buf.head) != NULL) {
278 tty->buf.head = thead->next;
281 while((thead = tty->buf.free) != NULL) {
282 tty->buf.free = thead->next;
285 tty->buf.tail = NULL;
286 tty->buf.memory_used = 0;
290 * tty_buffer_init - prepare a tty buffer structure
291 * @tty: tty to initialise
293 * Set up the initial state of the buffer management for a tty device.
294 * Must be called before the other tty buffer functions are used.
299 static void tty_buffer_init(struct tty_struct *tty)
301 spin_lock_init(&tty->buf.lock);
302 tty->buf.head = NULL;
303 tty->buf.tail = NULL;
304 tty->buf.free = NULL;
305 tty->buf.memory_used = 0;
309 * tty_buffer_alloc - allocate a tty buffer
311 * @size: desired size (characters)
313 * Allocate a new tty buffer to hold the desired number of characters.
314 * Return NULL if out of memory or the allocation would exceed the
317 * Locking: Caller must hold tty->buf.lock
320 static struct tty_buffer *tty_buffer_alloc(struct tty_struct *tty, size_t size)
322 struct tty_buffer *p;
324 if (tty->buf.memory_used + size > 65536)
326 p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC);
334 p->char_buf_ptr = (char *)(p->data);
335 p->flag_buf_ptr = (unsigned char *)p->char_buf_ptr + size;
336 tty->buf.memory_used += size;
341 * tty_buffer_free - free a tty buffer
342 * @tty: tty owning the buffer
343 * @b: the buffer to free
345 * Free a tty buffer, or add it to the free list according to our
348 * Locking: Caller must hold tty->buf.lock
351 static void tty_buffer_free(struct tty_struct *tty, struct tty_buffer *b)
353 /* Dumb strategy for now - should keep some stats */
354 tty->buf.memory_used -= b->size;
355 WARN_ON(tty->buf.memory_used < 0);
360 b->next = tty->buf.free;
366 * tty_buffer_find - find a free tty buffer
367 * @tty: tty owning the buffer
368 * @size: characters wanted
370 * Locate an existing suitable tty buffer or if we are lacking one then
371 * allocate a new one. We round our buffers off in 256 character chunks
372 * to get better allocation behaviour.
374 * Locking: Caller must hold tty->buf.lock
377 static struct tty_buffer *tty_buffer_find(struct tty_struct *tty, size_t size)
379 struct tty_buffer **tbh = &tty->buf.free;
380 while((*tbh) != NULL) {
381 struct tty_buffer *t = *tbh;
382 if(t->size >= size) {
388 tty->buf.memory_used += t->size;
391 tbh = &((*tbh)->next);
393 /* Round the buffer size out */
394 size = (size + 0xFF) & ~ 0xFF;
395 return tty_buffer_alloc(tty, size);
396 /* Should possibly check if this fails for the largest buffer we
397 have queued and recycle that ? */
401 * tty_buffer_request_room - grow tty buffer if needed
402 * @tty: tty structure
403 * @size: size desired
405 * Make at least size bytes of linear space available for the tty
406 * buffer. If we fail return the size we managed to find.
408 * Locking: Takes tty->buf.lock
410 int tty_buffer_request_room(struct tty_struct *tty, size_t size)
412 struct tty_buffer *b, *n;
416 spin_lock_irqsave(&tty->buf.lock, flags);
418 /* OPTIMISATION: We could keep a per tty "zero" sized buffer to
419 remove this conditional if its worth it. This would be invisible
421 if ((b = tty->buf.tail) != NULL)
422 left = b->size - b->used;
427 /* This is the slow path - looking for new buffers to use */
428 if ((n = tty_buffer_find(tty, size)) != NULL) {
439 spin_unlock_irqrestore(&tty->buf.lock, flags);
442 EXPORT_SYMBOL_GPL(tty_buffer_request_room);
445 * tty_insert_flip_string - Add characters to the tty buffer
446 * @tty: tty structure
450 * Queue a series of bytes to the tty buffering. All the characters
451 * passed are marked as without error. Returns the number added.
453 * Locking: Called functions may take tty->buf.lock
456 int tty_insert_flip_string(struct tty_struct *tty, const unsigned char *chars,
461 int space = tty_buffer_request_room(tty, size - copied);
462 struct tty_buffer *tb = tty->buf.tail;
463 /* If there is no space then tb may be NULL */
464 if(unlikely(space == 0))
466 memcpy(tb->char_buf_ptr + tb->used, chars, space);
467 memset(tb->flag_buf_ptr + tb->used, TTY_NORMAL, space);
471 /* There is a small chance that we need to split the data over
472 several buffers. If this is the case we must loop */
473 } while (unlikely(size > copied));
476 EXPORT_SYMBOL(tty_insert_flip_string);
479 * tty_insert_flip_string_flags - Add characters to the tty buffer
480 * @tty: tty structure
485 * Queue a series of bytes to the tty buffering. For each character
486 * the flags array indicates the status of the character. Returns the
489 * Locking: Called functions may take tty->buf.lock
492 int tty_insert_flip_string_flags(struct tty_struct *tty,
493 const unsigned char *chars, const char *flags, size_t size)
497 int space = tty_buffer_request_room(tty, size - copied);
498 struct tty_buffer *tb = tty->buf.tail;
499 /* If there is no space then tb may be NULL */
500 if(unlikely(space == 0))
502 memcpy(tb->char_buf_ptr + tb->used, chars, space);
503 memcpy(tb->flag_buf_ptr + tb->used, flags, space);
508 /* There is a small chance that we need to split the data over
509 several buffers. If this is the case we must loop */
510 } while (unlikely(size > copied));
513 EXPORT_SYMBOL(tty_insert_flip_string_flags);
516 * tty_schedule_flip - push characters to ldisc
517 * @tty: tty to push from
519 * Takes any pending buffers and transfers their ownership to the
520 * ldisc side of the queue. It then schedules those characters for
521 * processing by the line discipline.
523 * Locking: Takes tty->buf.lock
526 void tty_schedule_flip(struct tty_struct *tty)
529 spin_lock_irqsave(&tty->buf.lock, flags);
530 if (tty->buf.tail != NULL)
531 tty->buf.tail->commit = tty->buf.tail->used;
532 spin_unlock_irqrestore(&tty->buf.lock, flags);
533 schedule_delayed_work(&tty->buf.work, 1);
535 EXPORT_SYMBOL(tty_schedule_flip);
538 * tty_prepare_flip_string - make room for characters
540 * @chars: return pointer for character write area
541 * @size: desired size
543 * Prepare a block of space in the buffer for data. Returns the length
544 * available and buffer pointer to the space which is now allocated and
545 * accounted for as ready for normal characters. This is used for drivers
546 * that need their own block copy routines into the buffer. There is no
547 * guarantee the buffer is a DMA target!
549 * Locking: May call functions taking tty->buf.lock
552 int tty_prepare_flip_string(struct tty_struct *tty, unsigned char **chars, size_t size)
554 int space = tty_buffer_request_room(tty, size);
556 struct tty_buffer *tb = tty->buf.tail;
557 *chars = tb->char_buf_ptr + tb->used;
558 memset(tb->flag_buf_ptr + tb->used, TTY_NORMAL, space);
564 EXPORT_SYMBOL_GPL(tty_prepare_flip_string);
567 * tty_prepare_flip_string_flags - make room for characters
569 * @chars: return pointer for character write area
570 * @flags: return pointer for status flag write area
571 * @size: desired size
573 * Prepare a block of space in the buffer for data. Returns the length
574 * available and buffer pointer to the space which is now allocated and
575 * accounted for as ready for characters. This is used for drivers
576 * that need their own block copy routines into the buffer. There is no
577 * guarantee the buffer is a DMA target!
579 * Locking: May call functions taking tty->buf.lock
582 int tty_prepare_flip_string_flags(struct tty_struct *tty, unsigned char **chars, char **flags, size_t size)
584 int space = tty_buffer_request_room(tty, size);
586 struct tty_buffer *tb = tty->buf.tail;
587 *chars = tb->char_buf_ptr + tb->used;
588 *flags = tb->flag_buf_ptr + tb->used;
594 EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags);
599 * tty_set_termios_ldisc - set ldisc field
600 * @tty: tty structure
601 * @num: line discipline number
603 * This is probably overkill for real world processors but
604 * they are not on hot paths so a little discipline won't do
607 * Locking: takes termios_mutex
610 static void tty_set_termios_ldisc(struct tty_struct *tty, int num)
612 mutex_lock(&tty->termios_mutex);
613 tty->termios->c_line = num;
614 mutex_unlock(&tty->termios_mutex);
618 * This guards the refcounted line discipline lists. The lock
619 * must be taken with irqs off because there are hangup path
620 * callers who will do ldisc lookups and cannot sleep.
623 static DEFINE_SPINLOCK(tty_ldisc_lock);
624 static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_wait);
625 static struct tty_ldisc tty_ldiscs[NR_LDISCS]; /* line disc dispatch table */
628 * tty_register_ldisc - install a line discipline
629 * @disc: ldisc number
630 * @new_ldisc: pointer to the ldisc object
632 * Installs a new line discipline into the kernel. The discipline
633 * is set up as unreferenced and then made available to the kernel
634 * from this point onwards.
637 * takes tty_ldisc_lock to guard against ldisc races
640 int tty_register_ldisc(int disc, struct tty_ldisc *new_ldisc)
645 if (disc < N_TTY || disc >= NR_LDISCS)
648 spin_lock_irqsave(&tty_ldisc_lock, flags);
649 tty_ldiscs[disc] = *new_ldisc;
650 tty_ldiscs[disc].num = disc;
651 tty_ldiscs[disc].flags |= LDISC_FLAG_DEFINED;
652 tty_ldiscs[disc].refcount = 0;
653 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
657 EXPORT_SYMBOL(tty_register_ldisc);
660 * tty_unregister_ldisc - unload a line discipline
661 * @disc: ldisc number
662 * @new_ldisc: pointer to the ldisc object
664 * Remove a line discipline from the kernel providing it is not
668 * takes tty_ldisc_lock to guard against ldisc races
671 int tty_unregister_ldisc(int disc)
676 if (disc < N_TTY || disc >= NR_LDISCS)
679 spin_lock_irqsave(&tty_ldisc_lock, flags);
680 if (tty_ldiscs[disc].refcount)
683 tty_ldiscs[disc].flags &= ~LDISC_FLAG_DEFINED;
684 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
688 EXPORT_SYMBOL(tty_unregister_ldisc);
691 * tty_ldisc_get - take a reference to an ldisc
692 * @disc: ldisc number
694 * Takes a reference to a line discipline. Deals with refcounts and
695 * module locking counts. Returns NULL if the discipline is not available.
696 * Returns a pointer to the discipline and bumps the ref count if it is
700 * takes tty_ldisc_lock to guard against ldisc races
703 struct tty_ldisc *tty_ldisc_get(int disc)
706 struct tty_ldisc *ld;
708 if (disc < N_TTY || disc >= NR_LDISCS)
711 spin_lock_irqsave(&tty_ldisc_lock, flags);
713 ld = &tty_ldiscs[disc];
714 /* Check the entry is defined */
715 if(ld->flags & LDISC_FLAG_DEFINED)
717 /* If the module is being unloaded we can't use it */
718 if (!try_module_get(ld->owner))
725 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
729 EXPORT_SYMBOL_GPL(tty_ldisc_get);
732 * tty_ldisc_put - drop ldisc reference
733 * @disc: ldisc number
735 * Drop a reference to a line discipline. Manage refcounts and
736 * module usage counts
739 * takes tty_ldisc_lock to guard against ldisc races
742 void tty_ldisc_put(int disc)
744 struct tty_ldisc *ld;
747 BUG_ON(disc < N_TTY || disc >= NR_LDISCS);
749 spin_lock_irqsave(&tty_ldisc_lock, flags);
750 ld = &tty_ldiscs[disc];
751 BUG_ON(ld->refcount == 0);
753 module_put(ld->owner);
754 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
757 EXPORT_SYMBOL_GPL(tty_ldisc_put);
760 * tty_ldisc_assign - set ldisc on a tty
761 * @tty: tty to assign
762 * @ld: line discipline
764 * Install an instance of a line discipline into a tty structure. The
765 * ldisc must have a reference count above zero to ensure it remains/
766 * The tty instance refcount starts at zero.
769 * Caller must hold references
772 static void tty_ldisc_assign(struct tty_struct *tty, struct tty_ldisc *ld)
775 tty->ldisc.refcount = 0;
779 * tty_ldisc_try - internal helper
782 * Make a single attempt to grab and bump the refcount on
783 * the tty ldisc. Return 0 on failure or 1 on success. This is
784 * used to implement both the waiting and non waiting versions
787 * Locking: takes tty_ldisc_lock
790 static int tty_ldisc_try(struct tty_struct *tty)
793 struct tty_ldisc *ld;
796 spin_lock_irqsave(&tty_ldisc_lock, flags);
798 if(test_bit(TTY_LDISC, &tty->flags))
803 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
808 * tty_ldisc_ref_wait - wait for the tty ldisc
811 * Dereference the line discipline for the terminal and take a
812 * reference to it. If the line discipline is in flux then
813 * wait patiently until it changes.
815 * Note: Must not be called from an IRQ/timer context. The caller
816 * must also be careful not to hold other locks that will deadlock
817 * against a discipline change, such as an existing ldisc reference
818 * (which we check for)
820 * Locking: call functions take tty_ldisc_lock
823 struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty)
825 /* wait_event is a macro */
826 wait_event(tty_ldisc_wait, tty_ldisc_try(tty));
827 if(tty->ldisc.refcount == 0)
828 printk(KERN_ERR "tty_ldisc_ref_wait\n");
832 EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait);
835 * tty_ldisc_ref - get the tty ldisc
838 * Dereference the line discipline for the terminal and take a
839 * reference to it. If the line discipline is in flux then
840 * return NULL. Can be called from IRQ and timer functions.
842 * Locking: called functions take tty_ldisc_lock
845 struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty)
847 if(tty_ldisc_try(tty))
852 EXPORT_SYMBOL_GPL(tty_ldisc_ref);
855 * tty_ldisc_deref - free a tty ldisc reference
856 * @ld: reference to free up
858 * Undoes the effect of tty_ldisc_ref or tty_ldisc_ref_wait. May
859 * be called in IRQ context.
861 * Locking: takes tty_ldisc_lock
864 void tty_ldisc_deref(struct tty_ldisc *ld)
870 spin_lock_irqsave(&tty_ldisc_lock, flags);
871 if(ld->refcount == 0)
872 printk(KERN_ERR "tty_ldisc_deref: no references.\n");
875 if(ld->refcount == 0)
876 wake_up(&tty_ldisc_wait);
877 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
880 EXPORT_SYMBOL_GPL(tty_ldisc_deref);
883 * tty_ldisc_enable - allow ldisc use
884 * @tty: terminal to activate ldisc on
886 * Set the TTY_LDISC flag when the line discipline can be called
887 * again. Do neccessary wakeups for existing sleepers.
889 * Note: nobody should set this bit except via this function. Clearing
890 * directly is allowed.
893 static void tty_ldisc_enable(struct tty_struct *tty)
895 set_bit(TTY_LDISC, &tty->flags);
896 wake_up(&tty_ldisc_wait);
900 * tty_set_ldisc - set line discipline
901 * @tty: the terminal to set
902 * @ldisc: the line discipline
904 * Set the discipline of a tty line. Must be called from a process
907 * Locking: takes tty_ldisc_lock.
908 * called functions take termios_mutex
911 static int tty_set_ldisc(struct tty_struct *tty, int ldisc)
914 struct tty_ldisc o_ldisc;
918 struct tty_ldisc *ld;
919 struct tty_struct *o_tty;
921 if ((ldisc < N_TTY) || (ldisc >= NR_LDISCS))
926 ld = tty_ldisc_get(ldisc);
927 /* Eduardo Blanco <ejbs@cs.cs.com.uy> */
928 /* Cyrus Durgin <cider@speakeasy.org> */
930 request_module("tty-ldisc-%d", ldisc);
931 ld = tty_ldisc_get(ldisc);
937 * No more input please, we are switching. The new ldisc
938 * will update this value in the ldisc open function
941 tty->receive_room = 0;
944 * Problem: What do we do if this blocks ?
947 tty_wait_until_sent(tty, 0);
949 if (tty->ldisc.num == ldisc) {
950 tty_ldisc_put(ldisc);
954 o_ldisc = tty->ldisc;
958 * Make sure we don't change while someone holds a
959 * reference to the line discipline. The TTY_LDISC bit
960 * prevents anyone taking a reference once it is clear.
961 * We need the lock to avoid racing reference takers.
964 spin_lock_irqsave(&tty_ldisc_lock, flags);
965 if (tty->ldisc.refcount || (o_tty && o_tty->ldisc.refcount)) {
966 if(tty->ldisc.refcount) {
967 /* Free the new ldisc we grabbed. Must drop the lock
969 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
970 tty_ldisc_put(ldisc);
972 * There are several reasons we may be busy, including
973 * random momentary I/O traffic. We must therefore
974 * retry. We could distinguish between blocking ops
975 * and retries if we made tty_ldisc_wait() smarter. That
976 * is up for discussion.
978 if (wait_event_interruptible(tty_ldisc_wait, tty->ldisc.refcount == 0) < 0)
982 if(o_tty && o_tty->ldisc.refcount) {
983 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
984 tty_ldisc_put(ldisc);
985 if (wait_event_interruptible(tty_ldisc_wait, o_tty->ldisc.refcount == 0) < 0)
991 /* if the TTY_LDISC bit is set, then we are racing against another ldisc change */
993 if (!test_bit(TTY_LDISC, &tty->flags)) {
994 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
995 tty_ldisc_put(ldisc);
996 ld = tty_ldisc_ref_wait(tty);
1001 clear_bit(TTY_LDISC, &tty->flags);
1003 clear_bit(TTY_LDISC, &o_tty->flags);
1004 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
1007 * From this point on we know nobody has an ldisc
1008 * usage reference, nor can they obtain one until
1009 * we say so later on.
1012 work = cancel_delayed_work(&tty->buf.work);
1014 * Wait for ->hangup_work and ->buf.work handlers to terminate
1017 flush_scheduled_work();
1018 /* Shutdown the current discipline. */
1019 if (tty->ldisc.close)
1020 (tty->ldisc.close)(tty);
1022 /* Now set up the new line discipline. */
1023 tty_ldisc_assign(tty, ld);
1024 tty_set_termios_ldisc(tty, ldisc);
1025 if (tty->ldisc.open)
1026 retval = (tty->ldisc.open)(tty);
1028 tty_ldisc_put(ldisc);
1029 /* There is an outstanding reference here so this is safe */
1030 tty_ldisc_assign(tty, tty_ldisc_get(o_ldisc.num));
1031 tty_set_termios_ldisc(tty, tty->ldisc.num);
1032 if (tty->ldisc.open && (tty->ldisc.open(tty) < 0)) {
1033 tty_ldisc_put(o_ldisc.num);
1034 /* This driver is always present */
1035 tty_ldisc_assign(tty, tty_ldisc_get(N_TTY));
1036 tty_set_termios_ldisc(tty, N_TTY);
1037 if (tty->ldisc.open) {
1038 int r = tty->ldisc.open(tty);
1041 panic("Couldn't open N_TTY ldisc for "
1043 tty_name(tty, buf), r);
1047 /* At this point we hold a reference to the new ldisc and a
1048 a reference to the old ldisc. If we ended up flipping back
1049 to the existing ldisc we have two references to it */
1051 if (tty->ldisc.num != o_ldisc.num && tty->driver->set_ldisc)
1052 tty->driver->set_ldisc(tty);
1054 tty_ldisc_put(o_ldisc.num);
1057 * Allow ldisc referencing to occur as soon as the driver
1058 * ldisc callback completes.
1061 tty_ldisc_enable(tty);
1063 tty_ldisc_enable(o_tty);
1065 /* Restart it in case no characters kick it off. Safe if
1068 schedule_delayed_work(&tty->buf.work, 1);
1073 * get_tty_driver - find device of a tty
1074 * @dev_t: device identifier
1075 * @index: returns the index of the tty
1077 * This routine returns a tty driver structure, given a device number
1078 * and also passes back the index number.
1080 * Locking: caller must hold tty_mutex
1083 static struct tty_driver *get_tty_driver(dev_t device, int *index)
1085 struct tty_driver *p;
1087 list_for_each_entry(p, &tty_drivers, tty_drivers) {
1088 dev_t base = MKDEV(p->major, p->minor_start);
1089 if (device < base || device >= base + p->num)
1091 *index = device - base;
1098 * tty_check_change - check for POSIX terminal changes
1099 * @tty: tty to check
1101 * If we try to write to, or set the state of, a terminal and we're
1102 * not in the foreground, send a SIGTTOU. If the signal is blocked or
1103 * ignored, go ahead and perform the operation. (POSIX 7.2)
1108 int tty_check_change(struct tty_struct * tty)
1110 if (current->signal->tty != tty)
1112 if (tty->pgrp <= 0) {
1113 printk(KERN_WARNING "tty_check_change: tty->pgrp <= 0!\n");
1116 if (process_group(current) == tty->pgrp)
1118 if (is_ignored(SIGTTOU))
1120 if (is_orphaned_pgrp(process_group(current)))
1122 (void) kill_pg(process_group(current), SIGTTOU, 1);
1123 return -ERESTARTSYS;
1126 EXPORT_SYMBOL(tty_check_change);
1128 static ssize_t hung_up_tty_read(struct file * file, char __user * buf,
1129 size_t count, loff_t *ppos)
1134 static ssize_t hung_up_tty_write(struct file * file, const char __user * buf,
1135 size_t count, loff_t *ppos)
1140 /* No kernel lock held - none needed ;) */
1141 static unsigned int hung_up_tty_poll(struct file * filp, poll_table * wait)
1143 return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM;
1146 static int hung_up_tty_ioctl(struct inode * inode, struct file * file,
1147 unsigned int cmd, unsigned long arg)
1149 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
1152 static const struct file_operations tty_fops = {
1153 .llseek = no_llseek,
1159 .release = tty_release,
1160 .fasync = tty_fasync,
1163 #ifdef CONFIG_UNIX98_PTYS
1164 static const struct file_operations ptmx_fops = {
1165 .llseek = no_llseek,
1171 .release = tty_release,
1172 .fasync = tty_fasync,
1176 static const struct file_operations console_fops = {
1177 .llseek = no_llseek,
1179 .write = redirected_tty_write,
1183 .release = tty_release,
1184 .fasync = tty_fasync,
1187 static const struct file_operations hung_up_tty_fops = {
1188 .llseek = no_llseek,
1189 .read = hung_up_tty_read,
1190 .write = hung_up_tty_write,
1191 .poll = hung_up_tty_poll,
1192 .ioctl = hung_up_tty_ioctl,
1193 .release = tty_release,
1196 static DEFINE_SPINLOCK(redirect_lock);
1197 static struct file *redirect;
1200 * tty_wakeup - request more data
1203 * Internal and external helper for wakeups of tty. This function
1204 * informs the line discipline if present that the driver is ready
1205 * to receive more output data.
1208 void tty_wakeup(struct tty_struct *tty)
1210 struct tty_ldisc *ld;
1212 if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
1213 ld = tty_ldisc_ref(tty);
1215 if(ld->write_wakeup)
1216 ld->write_wakeup(tty);
1217 tty_ldisc_deref(ld);
1220 wake_up_interruptible(&tty->write_wait);
1223 EXPORT_SYMBOL_GPL(tty_wakeup);
1226 * tty_ldisc_flush - flush line discipline queue
1229 * Flush the line discipline queue (if any) for this tty. If there
1230 * is no line discipline active this is a no-op.
1233 void tty_ldisc_flush(struct tty_struct *tty)
1235 struct tty_ldisc *ld = tty_ldisc_ref(tty);
1237 if(ld->flush_buffer)
1238 ld->flush_buffer(tty);
1239 tty_ldisc_deref(ld);
1243 EXPORT_SYMBOL_GPL(tty_ldisc_flush);
1246 * tty_reset_termios - reset terminal state
1247 * @tty: tty to reset
1249 * Restore a terminal to the driver default state
1252 static void tty_reset_termios(struct tty_struct *tty)
1254 mutex_lock(&tty->termios_mutex);
1255 *tty->termios = tty->driver->init_termios;
1256 tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
1257 tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
1258 mutex_unlock(&tty->termios_mutex);
1262 * do_tty_hangup - actual handler for hangup events
1265 * This can be called by the "eventd" kernel thread. That is process
1266 * synchronous but doesn't hold any locks, so we need to make sure we
1267 * have the appropriate locks for what we're doing.
1269 * The hangup event clears any pending redirections onto the hung up
1270 * device. It ensures future writes will error and it does the needed
1271 * line discipline hangup and signal delivery. The tty object itself
1276 * redirect lock for undoing redirection
1277 * file list lock for manipulating list of ttys
1278 * tty_ldisc_lock from called functions
1279 * termios_mutex resetting termios data
1280 * tasklist_lock to walk task list for hangup event
1281 * ->siglock to protect ->signal/->sighand
1283 static void do_tty_hangup(struct work_struct *work)
1285 struct tty_struct *tty =
1286 container_of(work, struct tty_struct, hangup_work);
1287 struct file * cons_filp = NULL;
1288 struct file *filp, *f = NULL;
1289 struct task_struct *p;
1290 struct tty_ldisc *ld;
1291 int closecount = 0, n;
1296 /* inuse_filps is protected by the single kernel lock */
1299 spin_lock(&redirect_lock);
1300 if (redirect && redirect->private_data == tty) {
1304 spin_unlock(&redirect_lock);
1306 check_tty_count(tty, "do_tty_hangup");
1308 /* This breaks for file handles being sent over AF_UNIX sockets ? */
1309 list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) {
1310 if (filp->f_op->write == redirected_tty_write)
1312 if (filp->f_op->write != tty_write)
1315 tty_fasync(-1, filp, 0); /* can't block */
1316 filp->f_op = &hung_up_tty_fops;
1320 /* FIXME! What are the locking issues here? This may me overdoing things..
1321 * this question is especially important now that we've removed the irqlock. */
1323 ld = tty_ldisc_ref(tty);
1324 if(ld != NULL) /* We may have no line discipline at this point */
1326 if (ld->flush_buffer)
1327 ld->flush_buffer(tty);
1328 if (tty->driver->flush_buffer)
1329 tty->driver->flush_buffer(tty);
1330 if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) &&
1332 ld->write_wakeup(tty);
1337 /* FIXME: Once we trust the LDISC code better we can wait here for
1338 ldisc completion and fix the driver call race */
1340 wake_up_interruptible(&tty->write_wait);
1341 wake_up_interruptible(&tty->read_wait);
1344 * Shutdown the current line discipline, and reset it to
1347 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1348 tty_reset_termios(tty);
1350 /* Defer ldisc switch */
1351 /* tty_deferred_ldisc_switch(N_TTY);
1353 This should get done automatically when the port closes and
1354 tty_release is called */
1356 read_lock(&tasklist_lock);
1357 if (tty->session > 0) {
1358 do_each_task_pid(tty->session, PIDTYPE_SID, p) {
1359 spin_lock_irq(&p->sighand->siglock);
1360 if (p->signal->tty == tty)
1361 p->signal->tty = NULL;
1362 if (!p->signal->leader) {
1363 spin_unlock_irq(&p->sighand->siglock);
1366 __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
1367 __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
1369 p->signal->tty_old_pgrp = tty->pgrp;
1370 spin_unlock_irq(&p->sighand->siglock);
1371 } while_each_task_pid(tty->session, PIDTYPE_SID, p);
1373 read_unlock(&tasklist_lock);
1378 tty->ctrl_status = 0;
1380 * If one of the devices matches a console pointer, we
1381 * cannot just call hangup() because that will cause
1382 * tty->count and state->count to go out of sync.
1383 * So we just call close() the right number of times.
1386 if (tty->driver->close)
1387 for (n = 0; n < closecount; n++)
1388 tty->driver->close(tty, cons_filp);
1389 } else if (tty->driver->hangup)
1390 (tty->driver->hangup)(tty);
1392 /* We don't want to have driver/ldisc interactions beyond
1393 the ones we did here. The driver layer expects no
1394 calls after ->hangup() from the ldisc side. However we
1395 can't yet guarantee all that */
1397 set_bit(TTY_HUPPED, &tty->flags);
1399 tty_ldisc_enable(tty);
1400 tty_ldisc_deref(ld);
1408 * tty_hangup - trigger a hangup event
1409 * @tty: tty to hangup
1411 * A carrier loss (virtual or otherwise) has occurred on this like
1412 * schedule a hangup sequence to run after this event.
1415 void tty_hangup(struct tty_struct * tty)
1417 #ifdef TTY_DEBUG_HANGUP
1420 printk(KERN_DEBUG "%s hangup...\n", tty_name(tty, buf));
1422 schedule_work(&tty->hangup_work);
1425 EXPORT_SYMBOL(tty_hangup);
1428 * tty_vhangup - process vhangup
1429 * @tty: tty to hangup
1431 * The user has asked via system call for the terminal to be hung up.
1432 * We do this synchronously so that when the syscall returns the process
1433 * is complete. That guarantee is neccessary for security reasons.
1436 void tty_vhangup(struct tty_struct * tty)
1438 #ifdef TTY_DEBUG_HANGUP
1441 printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf));
1443 do_tty_hangup(&tty->hangup_work);
1445 EXPORT_SYMBOL(tty_vhangup);
1448 * tty_hung_up_p - was tty hung up
1449 * @filp: file pointer of tty
1451 * Return true if the tty has been subject to a vhangup or a carrier
1455 int tty_hung_up_p(struct file * filp)
1457 return (filp->f_op == &hung_up_tty_fops);
1460 EXPORT_SYMBOL(tty_hung_up_p);
1462 static void session_clear_tty(pid_t session)
1464 struct task_struct *p;
1465 do_each_task_pid(session, PIDTYPE_SID, p) {
1467 } while_each_task_pid(session, PIDTYPE_SID, p);
1471 * disassociate_ctty - disconnect controlling tty
1472 * @on_exit: true if exiting so need to "hang up" the session
1474 * This function is typically called only by the session leader, when
1475 * it wants to disassociate itself from its controlling tty.
1477 * It performs the following functions:
1478 * (1) Sends a SIGHUP and SIGCONT to the foreground process group
1479 * (2) Clears the tty from being controlling the session
1480 * (3) Clears the controlling tty for all processes in the
1483 * The argument on_exit is set to 1 if called when a process is
1484 * exiting; it is 0 if called by the ioctl TIOCNOTTY.
1487 * BKL is taken for hysterical raisins
1488 * tty_mutex is taken to protect tty
1489 * ->siglock is taken to protect ->signal/->sighand
1490 * tasklist_lock is taken to walk process list for sessions
1491 * ->siglock is taken to protect ->signal/->sighand
1494 void disassociate_ctty(int on_exit)
1496 struct tty_struct *tty;
1502 mutex_lock(&tty_mutex);
1503 tty = get_current_tty();
1505 tty_pgrp = tty->pgrp;
1506 mutex_unlock(&tty_mutex);
1507 /* XXX: here we race, there is nothing protecting tty */
1508 if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)
1511 pid_t old_pgrp = current->signal->tty_old_pgrp;
1513 kill_pg(old_pgrp, SIGHUP, on_exit);
1514 kill_pg(old_pgrp, SIGCONT, on_exit);
1516 mutex_unlock(&tty_mutex);
1521 kill_pg(tty_pgrp, SIGHUP, on_exit);
1523 kill_pg(tty_pgrp, SIGCONT, on_exit);
1526 spin_lock_irq(¤t->sighand->siglock);
1527 current->signal->tty_old_pgrp = 0;
1528 session = process_session(current);
1529 spin_unlock_irq(¤t->sighand->siglock);
1531 mutex_lock(&tty_mutex);
1532 /* It is possible that do_tty_hangup has free'd this tty */
1533 tty = get_current_tty();
1538 #ifdef TTY_DEBUG_HANGUP
1539 printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
1543 mutex_unlock(&tty_mutex);
1545 /* Now clear signal->tty under the lock */
1546 read_lock(&tasklist_lock);
1547 session_clear_tty(session);
1548 read_unlock(&tasklist_lock);
1554 * stop_tty - propogate flow control
1557 * Perform flow control to the driver. For PTY/TTY pairs we
1558 * must also propogate the TIOCKPKT status. May be called
1559 * on an already stopped device and will not re-call the driver
1562 * This functionality is used by both the line disciplines for
1563 * halting incoming flow and by the driver. It may therefore be
1564 * called from any context, may be under the tty atomic_write_lock
1568 * Broken. Relies on BKL which is unsafe here.
1571 void stop_tty(struct tty_struct *tty)
1576 if (tty->link && tty->link->packet) {
1577 tty->ctrl_status &= ~TIOCPKT_START;
1578 tty->ctrl_status |= TIOCPKT_STOP;
1579 wake_up_interruptible(&tty->link->read_wait);
1581 if (tty->driver->stop)
1582 (tty->driver->stop)(tty);
1585 EXPORT_SYMBOL(stop_tty);
1588 * start_tty - propogate flow control
1589 * @tty: tty to start
1591 * Start a tty that has been stopped if at all possible. Perform
1592 * any neccessary wakeups and propogate the TIOCPKT status. If this
1593 * is the tty was previous stopped and is being started then the
1594 * driver start method is invoked and the line discipline woken.
1597 * Broken. Relies on BKL which is unsafe here.
1600 void start_tty(struct tty_struct *tty)
1602 if (!tty->stopped || tty->flow_stopped)
1605 if (tty->link && tty->link->packet) {
1606 tty->ctrl_status &= ~TIOCPKT_STOP;
1607 tty->ctrl_status |= TIOCPKT_START;
1608 wake_up_interruptible(&tty->link->read_wait);
1610 if (tty->driver->start)
1611 (tty->driver->start)(tty);
1613 /* If we have a running line discipline it may need kicking */
1617 EXPORT_SYMBOL(start_tty);
1620 * tty_read - read method for tty device files
1621 * @file: pointer to tty file
1623 * @count: size of user buffer
1626 * Perform the read system call function on this terminal device. Checks
1627 * for hung up devices before calling the line discipline method.
1630 * Locks the line discipline internally while needed
1631 * For historical reasons the line discipline read method is
1632 * invoked under the BKL. This will go away in time so do not rely on it
1633 * in new code. Multiple read calls may be outstanding in parallel.
1636 static ssize_t tty_read(struct file * file, char __user * buf, size_t count,
1640 struct tty_struct * tty;
1641 struct inode *inode;
1642 struct tty_ldisc *ld;
1644 tty = (struct tty_struct *)file->private_data;
1645 inode = file->f_path.dentry->d_inode;
1646 if (tty_paranoia_check(tty, inode, "tty_read"))
1648 if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags)))
1651 /* We want to wait for the line discipline to sort out in this
1653 ld = tty_ldisc_ref_wait(tty);
1656 i = (ld->read)(tty,file,buf,count);
1659 tty_ldisc_deref(ld);
1662 inode->i_atime = current_fs_time(inode->i_sb);
1667 * Split writes up in sane blocksizes to avoid
1668 * denial-of-service type attacks
1670 static inline ssize_t do_tty_write(
1671 ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
1672 struct tty_struct *tty,
1674 const char __user *buf,
1677 ssize_t ret = 0, written = 0;
1680 /* FIXME: O_NDELAY ... */
1681 if (mutex_lock_interruptible(&tty->atomic_write_lock)) {
1682 return -ERESTARTSYS;
1686 * We chunk up writes into a temporary buffer. This
1687 * simplifies low-level drivers immensely, since they
1688 * don't have locking issues and user mode accesses.
1690 * But if TTY_NO_WRITE_SPLIT is set, we should use a
1693 * The default chunk-size is 2kB, because the NTTY
1694 * layer has problems with bigger chunks. It will
1695 * claim to be able to handle more characters than
1698 * FIXME: This can probably go away now except that 64K chunks
1699 * are too likely to fail unless switched to vmalloc...
1702 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
1707 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
1708 if (tty->write_cnt < chunk) {
1714 buf = kmalloc(chunk, GFP_KERNEL);
1716 mutex_unlock(&tty->atomic_write_lock);
1719 kfree(tty->write_buf);
1720 tty->write_cnt = chunk;
1721 tty->write_buf = buf;
1724 /* Do the write .. */
1726 size_t size = count;
1730 if (copy_from_user(tty->write_buf, buf, size))
1733 ret = write(tty, file, tty->write_buf, size);
1743 if (signal_pending(current))
1748 struct inode *inode = file->f_path.dentry->d_inode;
1749 inode->i_mtime = current_fs_time(inode->i_sb);
1752 mutex_unlock(&tty->atomic_write_lock);
1758 * tty_write - write method for tty device file
1759 * @file: tty file pointer
1760 * @buf: user data to write
1761 * @count: bytes to write
1764 * Write data to a tty device via the line discipline.
1767 * Locks the line discipline as required
1768 * Writes to the tty driver are serialized by the atomic_write_lock
1769 * and are then processed in chunks to the device. The line discipline
1770 * write method will not be involked in parallel for each device
1771 * The line discipline write method is called under the big
1772 * kernel lock for historical reasons. New code should not rely on this.
1775 static ssize_t tty_write(struct file * file, const char __user * buf, size_t count,
1778 struct tty_struct * tty;
1779 struct inode *inode = file->f_path.dentry->d_inode;
1781 struct tty_ldisc *ld;
1783 tty = (struct tty_struct *)file->private_data;
1784 if (tty_paranoia_check(tty, inode, "tty_write"))
1786 if (!tty || !tty->driver->write || (test_bit(TTY_IO_ERROR, &tty->flags)))
1789 ld = tty_ldisc_ref_wait(tty);
1793 ret = do_tty_write(ld->write, tty, file, buf, count);
1794 tty_ldisc_deref(ld);
1798 ssize_t redirected_tty_write(struct file * file, const char __user * buf, size_t count,
1801 struct file *p = NULL;
1803 spin_lock(&redirect_lock);
1808 spin_unlock(&redirect_lock);
1812 res = vfs_write(p, buf, count, &p->f_pos);
1817 return tty_write(file, buf, count, ppos);
1820 static char ptychar[] = "pqrstuvwxyzabcde";
1823 * pty_line_name - generate name for a pty
1824 * @driver: the tty driver in use
1825 * @index: the minor number
1826 * @p: output buffer of at least 6 bytes
1828 * Generate a name from a driver reference and write it to the output
1833 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1835 int i = index + driver->name_base;
1836 /* ->name is initialized to "ttyp", but "tty" is expected */
1837 sprintf(p, "%s%c%x",
1838 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1839 ptychar[i >> 4 & 0xf], i & 0xf);
1843 * pty_line_name - generate name for a tty
1844 * @driver: the tty driver in use
1845 * @index: the minor number
1846 * @p: output buffer of at least 7 bytes
1848 * Generate a name from a driver reference and write it to the output
1853 static void tty_line_name(struct tty_driver *driver, int index, char *p)
1855 sprintf(p, "%s%d", driver->name, index + driver->name_base);
1859 * init_dev - initialise a tty device
1860 * @driver: tty driver we are opening a device on
1861 * @idx: device index
1862 * @tty: returned tty structure
1864 * Prepare a tty device. This may not be a "new" clean device but
1865 * could also be an active device. The pty drivers require special
1866 * handling because of this.
1869 * The function is called under the tty_mutex, which
1870 * protects us from the tty struct or driver itself going away.
1872 * On exit the tty device has the line discipline attached and
1873 * a reference count of 1. If a pair was created for pty/tty use
1874 * and the other was a pty master then it too has a reference count of 1.
1876 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1877 * failed open. The new code protects the open with a mutex, so it's
1878 * really quite straightforward. The mutex locking can probably be
1879 * relaxed for the (most common) case of reopening a tty.
1882 static int init_dev(struct tty_driver *driver, int idx,
1883 struct tty_struct **ret_tty)
1885 struct tty_struct *tty, *o_tty;
1886 struct ktermios *tp, **tp_loc, *o_tp, **o_tp_loc;
1887 struct ktermios *ltp, **ltp_loc, *o_ltp, **o_ltp_loc;
1890 /* check whether we're reopening an existing tty */
1891 if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
1892 tty = devpts_get_tty(idx);
1893 if (tty && driver->subtype == PTY_TYPE_MASTER)
1896 tty = driver->ttys[idx];
1898 if (tty) goto fast_track;
1901 * First time open is complex, especially for PTY devices.
1902 * This code guarantees that either everything succeeds and the
1903 * TTY is ready for operation, or else the table slots are vacated
1904 * and the allocated memory released. (Except that the termios
1905 * and locked termios may be retained.)
1908 if (!try_module_get(driver->owner)) {
1917 tty = alloc_tty_struct();
1920 initialize_tty_struct(tty);
1921 tty->driver = driver;
1923 tty_line_name(driver, idx, tty->name);
1925 if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
1926 tp_loc = &tty->termios;
1927 ltp_loc = &tty->termios_locked;
1929 tp_loc = &driver->termios[idx];
1930 ltp_loc = &driver->termios_locked[idx];
1934 tp = (struct ktermios *) kmalloc(sizeof(struct ktermios),
1938 *tp = driver->init_termios;
1942 ltp = (struct ktermios *) kmalloc(sizeof(struct ktermios),
1946 memset(ltp, 0, sizeof(struct ktermios));
1949 if (driver->type == TTY_DRIVER_TYPE_PTY) {
1950 o_tty = alloc_tty_struct();
1953 initialize_tty_struct(o_tty);
1954 o_tty->driver = driver->other;
1956 tty_line_name(driver->other, idx, o_tty->name);
1958 if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
1959 o_tp_loc = &o_tty->termios;
1960 o_ltp_loc = &o_tty->termios_locked;
1962 o_tp_loc = &driver->other->termios[idx];
1963 o_ltp_loc = &driver->other->termios_locked[idx];
1967 o_tp = (struct ktermios *)
1968 kmalloc(sizeof(struct ktermios), GFP_KERNEL);
1971 *o_tp = driver->other->init_termios;
1975 o_ltp = (struct ktermios *)
1976 kmalloc(sizeof(struct ktermios), GFP_KERNEL);
1979 memset(o_ltp, 0, sizeof(struct ktermios));
1983 * Everything allocated ... set up the o_tty structure.
1985 if (!(driver->other->flags & TTY_DRIVER_DEVPTS_MEM)) {
1986 driver->other->ttys[idx] = o_tty;
1992 o_tty->termios = *o_tp_loc;
1993 o_tty->termios_locked = *o_ltp_loc;
1994 driver->other->refcount++;
1995 if (driver->subtype == PTY_TYPE_MASTER)
1998 /* Establish the links in both directions */
2004 * All structures have been allocated, so now we install them.
2005 * Failures after this point use release_mem to clean up, so
2006 * there's no need to null out the local pointers.
2008 if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
2009 driver->ttys[idx] = tty;
2016 tty->termios = *tp_loc;
2017 tty->termios_locked = *ltp_loc;
2018 /* Compatibility until drivers always set this */
2019 tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
2020 tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
2025 * Structures all installed ... call the ldisc open routines.
2026 * If we fail here just call release_mem to clean up. No need
2027 * to decrement the use counts, as release_mem doesn't care.
2030 if (tty->ldisc.open) {
2031 retval = (tty->ldisc.open)(tty);
2033 goto release_mem_out;
2035 if (o_tty && o_tty->ldisc.open) {
2036 retval = (o_tty->ldisc.open)(o_tty);
2038 if (tty->ldisc.close)
2039 (tty->ldisc.close)(tty);
2040 goto release_mem_out;
2042 tty_ldisc_enable(o_tty);
2044 tty_ldisc_enable(tty);
2048 * This fast open can be used if the tty is already open.
2049 * No memory is allocated, and the only failures are from
2050 * attempting to open a closing tty or attempting multiple
2051 * opens on a pty master.
2054 if (test_bit(TTY_CLOSING, &tty->flags)) {
2058 if (driver->type == TTY_DRIVER_TYPE_PTY &&
2059 driver->subtype == PTY_TYPE_MASTER) {
2061 * special case for PTY masters: only one open permitted,
2062 * and the slave side open count is incremented as well.
2071 tty->driver = driver; /* N.B. why do this every time?? */
2074 if(!test_bit(TTY_LDISC, &tty->flags))
2075 printk(KERN_ERR "init_dev but no ldisc\n");
2079 /* All paths come through here to release the mutex */
2083 /* Release locally allocated memory ... nothing placed in slots */
2087 free_tty_struct(o_tty);
2090 free_tty_struct(tty);
2093 module_put(driver->owner);
2097 /* call the tty release_mem routine to clean out this slot */
2099 if (printk_ratelimit())
2100 printk(KERN_INFO "init_dev: ldisc open failed, "
2101 "clearing slot %d\n", idx);
2102 release_mem(tty, idx);
2107 * release_mem - release tty structure memory
2109 * Releases memory associated with a tty structure, and clears out the
2110 * driver table slots. This function is called when a device is no longer
2111 * in use. It also gets called when setup of a device fails.
2114 * tty_mutex - sometimes only
2115 * takes the file list lock internally when working on the list
2116 * of ttys that the driver keeps.
2117 * FIXME: should we require tty_mutex is held here ??
2120 static void release_mem(struct tty_struct *tty, int idx)
2122 struct tty_struct *o_tty;
2123 struct ktermios *tp;
2124 int devpts = tty->driver->flags & TTY_DRIVER_DEVPTS_MEM;
2126 if ((o_tty = tty->link) != NULL) {
2128 o_tty->driver->ttys[idx] = NULL;
2129 if (o_tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
2130 tp = o_tty->termios;
2132 o_tty->driver->termios[idx] = NULL;
2135 tp = o_tty->termios_locked;
2137 o_tty->driver->termios_locked[idx] = NULL;
2141 o_tty->driver->refcount--;
2143 list_del_init(&o_tty->tty_files);
2145 free_tty_struct(o_tty);
2149 tty->driver->ttys[idx] = NULL;
2150 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
2153 tty->driver->termios[idx] = NULL;
2156 tp = tty->termios_locked;
2158 tty->driver->termios_locked[idx] = NULL;
2163 tty->driver->refcount--;
2165 list_del_init(&tty->tty_files);
2167 module_put(tty->driver->owner);
2168 free_tty_struct(tty);
2172 * Even releasing the tty structures is a tricky business.. We have
2173 * to be very careful that the structures are all released at the
2174 * same time, as interrupts might otherwise get the wrong pointers.
2176 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
2177 * lead to double frees or releasing memory still in use.
2179 static void release_dev(struct file * filp)
2181 struct tty_struct *tty, *o_tty;
2182 int pty_master, tty_closing, o_tty_closing, do_sleep;
2186 unsigned long flags;
2188 tty = (struct tty_struct *)filp->private_data;
2189 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "release_dev"))
2192 check_tty_count(tty, "release_dev");
2194 tty_fasync(-1, filp, 0);
2197 pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2198 tty->driver->subtype == PTY_TYPE_MASTER);
2199 devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0;
2202 #ifdef TTY_PARANOIA_CHECK
2203 if (idx < 0 || idx >= tty->driver->num) {
2204 printk(KERN_DEBUG "release_dev: bad idx when trying to "
2205 "free (%s)\n", tty->name);
2208 if (!(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
2209 if (tty != tty->driver->ttys[idx]) {
2210 printk(KERN_DEBUG "release_dev: driver.table[%d] not tty "
2211 "for (%s)\n", idx, tty->name);
2214 if (tty->termios != tty->driver->termios[idx]) {
2215 printk(KERN_DEBUG "release_dev: driver.termios[%d] not termios "
2220 if (tty->termios_locked != tty->driver->termios_locked[idx]) {
2221 printk(KERN_DEBUG "release_dev: driver.termios_locked[%d] not "
2222 "termios_locked for (%s)\n",
2229 #ifdef TTY_DEBUG_HANGUP
2230 printk(KERN_DEBUG "release_dev of %s (tty count=%d)...",
2231 tty_name(tty, buf), tty->count);
2234 #ifdef TTY_PARANOIA_CHECK
2235 if (tty->driver->other &&
2236 !(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
2237 if (o_tty != tty->driver->other->ttys[idx]) {
2238 printk(KERN_DEBUG "release_dev: other->table[%d] "
2239 "not o_tty for (%s)\n",
2243 if (o_tty->termios != tty->driver->other->termios[idx]) {
2244 printk(KERN_DEBUG "release_dev: other->termios[%d] "
2245 "not o_termios for (%s)\n",
2249 if (o_tty->termios_locked !=
2250 tty->driver->other->termios_locked[idx]) {
2251 printk(KERN_DEBUG "release_dev: other->termios_locked["
2252 "%d] not o_termios_locked for (%s)\n",
2256 if (o_tty->link != tty) {
2257 printk(KERN_DEBUG "release_dev: bad pty pointers\n");
2262 if (tty->driver->close)
2263 tty->driver->close(tty, filp);
2266 * Sanity check: if tty->count is going to zero, there shouldn't be
2267 * any waiters on tty->read_wait or tty->write_wait. We test the
2268 * wait queues and kick everyone out _before_ actually starting to
2269 * close. This ensures that we won't block while releasing the tty
2272 * The test for the o_tty closing is necessary, since the master and
2273 * slave sides may close in any order. If the slave side closes out
2274 * first, its count will be one, since the master side holds an open.
2275 * Thus this test wouldn't be triggered at the time the slave closes,
2278 * Note that it's possible for the tty to be opened again while we're
2279 * flushing out waiters. By recalculating the closing flags before
2280 * each iteration we avoid any problems.
2283 /* Guard against races with tty->count changes elsewhere and
2284 opens on /dev/tty */
2286 mutex_lock(&tty_mutex);
2287 tty_closing = tty->count <= 1;
2288 o_tty_closing = o_tty &&
2289 (o_tty->count <= (pty_master ? 1 : 0));
2293 if (waitqueue_active(&tty->read_wait)) {
2294 wake_up(&tty->read_wait);
2297 if (waitqueue_active(&tty->write_wait)) {
2298 wake_up(&tty->write_wait);
2302 if (o_tty_closing) {
2303 if (waitqueue_active(&o_tty->read_wait)) {
2304 wake_up(&o_tty->read_wait);
2307 if (waitqueue_active(&o_tty->write_wait)) {
2308 wake_up(&o_tty->write_wait);
2315 printk(KERN_WARNING "release_dev: %s: read/write wait queue "
2316 "active!\n", tty_name(tty, buf));
2317 mutex_unlock(&tty_mutex);
2322 * The closing flags are now consistent with the open counts on
2323 * both sides, and we've completed the last operation that could
2324 * block, so it's safe to proceed with closing.
2327 if (--o_tty->count < 0) {
2328 printk(KERN_WARNING "release_dev: bad pty slave count "
2330 o_tty->count, tty_name(o_tty, buf));
2334 if (--tty->count < 0) {
2335 printk(KERN_WARNING "release_dev: bad tty->count (%d) for %s\n",
2336 tty->count, tty_name(tty, buf));
2341 * We've decremented tty->count, so we need to remove this file
2342 * descriptor off the tty->tty_files list; this serves two
2344 * - check_tty_count sees the correct number of file descriptors
2345 * associated with this tty.
2346 * - do_tty_hangup no longer sees this file descriptor as
2347 * something that needs to be handled for hangups.
2350 filp->private_data = NULL;
2353 * Perform some housekeeping before deciding whether to return.
2355 * Set the TTY_CLOSING flag if this was the last open. In the
2356 * case of a pty we may have to wait around for the other side
2357 * to close, and TTY_CLOSING makes sure we can't be reopened.
2360 set_bit(TTY_CLOSING, &tty->flags);
2362 set_bit(TTY_CLOSING, &o_tty->flags);
2365 * If _either_ side is closing, make sure there aren't any
2366 * processes that still think tty or o_tty is their controlling
2369 if (tty_closing || o_tty_closing) {
2370 read_lock(&tasklist_lock);
2371 session_clear_tty(tty->session);
2373 session_clear_tty(o_tty->session);
2374 read_unlock(&tasklist_lock);
2377 mutex_unlock(&tty_mutex);
2379 /* check whether both sides are closing ... */
2380 if (!tty_closing || (o_tty && !o_tty_closing))
2383 #ifdef TTY_DEBUG_HANGUP
2384 printk(KERN_DEBUG "freeing tty structure...");
2387 * Prevent flush_to_ldisc() from rescheduling the work for later. Then
2388 * kill any delayed work. As this is the final close it does not
2389 * race with the set_ldisc code path.
2391 clear_bit(TTY_LDISC, &tty->flags);
2392 cancel_delayed_work(&tty->buf.work);
2395 * Wait for ->hangup_work and ->buf.work handlers to terminate
2398 flush_scheduled_work();
2401 * Wait for any short term users (we know they are just driver
2402 * side waiters as the file is closing so user count on the file
2405 spin_lock_irqsave(&tty_ldisc_lock, flags);
2406 while(tty->ldisc.refcount)
2408 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
2409 wait_event(tty_ldisc_wait, tty->ldisc.refcount == 0);
2410 spin_lock_irqsave(&tty_ldisc_lock, flags);
2412 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
2414 * Shutdown the current line discipline, and reset it to N_TTY.
2415 * N.B. why reset ldisc when we're releasing the memory??
2417 * FIXME: this MUST get fixed for the new reflocking
2419 if (tty->ldisc.close)
2420 (tty->ldisc.close)(tty);
2421 tty_ldisc_put(tty->ldisc.num);
2424 * Switch the line discipline back
2426 tty_ldisc_assign(tty, tty_ldisc_get(N_TTY));
2427 tty_set_termios_ldisc(tty,N_TTY);
2429 /* FIXME: could o_tty be in setldisc here ? */
2430 clear_bit(TTY_LDISC, &o_tty->flags);
2431 if (o_tty->ldisc.close)
2432 (o_tty->ldisc.close)(o_tty);
2433 tty_ldisc_put(o_tty->ldisc.num);
2434 tty_ldisc_assign(o_tty, tty_ldisc_get(N_TTY));
2435 tty_set_termios_ldisc(o_tty,N_TTY);
2438 * The release_mem function takes care of the details of clearing
2439 * the slots and preserving the termios structure.
2441 release_mem(tty, idx);
2443 #ifdef CONFIG_UNIX98_PTYS
2444 /* Make this pty number available for reallocation */
2446 down(&allocated_ptys_lock);
2447 idr_remove(&allocated_ptys, idx);
2448 up(&allocated_ptys_lock);
2455 * tty_open - open a tty device
2456 * @inode: inode of device file
2457 * @filp: file pointer to tty
2459 * tty_open and tty_release keep up the tty count that contains the
2460 * number of opens done on a tty. We cannot use the inode-count, as
2461 * different inodes might point to the same tty.
2463 * Open-counting is needed for pty masters, as well as for keeping
2464 * track of serial lines: DTR is dropped when the last close happens.
2465 * (This is not done solely through tty->count, now. - Ted 1/27/92)
2467 * The termios state of a pty is reset on first open so that
2468 * settings don't persist across reuse.
2470 * Locking: tty_mutex protects tty, get_tty_driver and init_dev work.
2471 * tty->count should protect the rest.
2472 * ->siglock protects ->signal/->sighand
2475 static int tty_open(struct inode * inode, struct file * filp)
2477 struct tty_struct *tty;
2479 struct tty_driver *driver;
2481 dev_t device = inode->i_rdev;
2482 unsigned short saved_flags = filp->f_flags;
2484 nonseekable_open(inode, filp);
2487 noctty = filp->f_flags & O_NOCTTY;
2491 mutex_lock(&tty_mutex);
2493 if (device == MKDEV(TTYAUX_MAJOR,0)) {
2494 tty = get_current_tty();
2496 mutex_unlock(&tty_mutex);
2499 driver = tty->driver;
2501 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
2506 if (device == MKDEV(TTY_MAJOR,0)) {
2507 extern struct tty_driver *console_driver;
2508 driver = console_driver;
2514 if (device == MKDEV(TTYAUX_MAJOR,1)) {
2515 driver = console_device(&index);
2517 /* Don't let /dev/console block */
2518 filp->f_flags |= O_NONBLOCK;
2522 mutex_unlock(&tty_mutex);
2526 driver = get_tty_driver(device, &index);
2528 mutex_unlock(&tty_mutex);
2532 retval = init_dev(driver, index, &tty);
2533 mutex_unlock(&tty_mutex);
2537 filp->private_data = tty;
2538 file_move(filp, &tty->tty_files);
2539 check_tty_count(tty, "tty_open");
2540 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2541 tty->driver->subtype == PTY_TYPE_MASTER)
2543 #ifdef TTY_DEBUG_HANGUP
2544 printk(KERN_DEBUG "opening %s...", tty->name);
2547 if (tty->driver->open)
2548 retval = tty->driver->open(tty, filp);
2552 filp->f_flags = saved_flags;
2554 if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
2558 #ifdef TTY_DEBUG_HANGUP
2559 printk(KERN_DEBUG "error %d in opening %s...", retval,
2563 if (retval != -ERESTARTSYS)
2565 if (signal_pending(current))
2569 * Need to reset f_op in case a hangup happened.
2571 if (filp->f_op == &hung_up_tty_fops)
2572 filp->f_op = &tty_fops;
2576 mutex_lock(&tty_mutex);
2577 spin_lock_irq(¤t->sighand->siglock);
2579 current->signal->leader &&
2580 !current->signal->tty &&
2582 __proc_set_tty(current, tty);
2583 spin_unlock_irq(¤t->sighand->siglock);
2584 mutex_unlock(&tty_mutex);
2588 #ifdef CONFIG_UNIX98_PTYS
2590 * ptmx_open - open a unix 98 pty master
2591 * @inode: inode of device file
2592 * @filp: file pointer to tty
2594 * Allocate a unix98 pty master device from the ptmx driver.
2596 * Locking: tty_mutex protects theinit_dev work. tty->count should
2598 * allocated_ptys_lock handles the list of free pty numbers
2601 static int ptmx_open(struct inode * inode, struct file * filp)
2603 struct tty_struct *tty;
2608 nonseekable_open(inode, filp);
2610 /* find a device that is not in use. */
2611 down(&allocated_ptys_lock);
2612 if (!idr_pre_get(&allocated_ptys, GFP_KERNEL)) {
2613 up(&allocated_ptys_lock);
2616 idr_ret = idr_get_new(&allocated_ptys, NULL, &index);
2618 up(&allocated_ptys_lock);
2619 if (idr_ret == -EAGAIN)
2623 if (index >= pty_limit) {
2624 idr_remove(&allocated_ptys, index);
2625 up(&allocated_ptys_lock);
2628 up(&allocated_ptys_lock);
2630 mutex_lock(&tty_mutex);
2631 retval = init_dev(ptm_driver, index, &tty);
2632 mutex_unlock(&tty_mutex);
2637 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
2638 filp->private_data = tty;
2639 file_move(filp, &tty->tty_files);
2642 if (devpts_pty_new(tty->link))
2645 check_tty_count(tty, "tty_open");
2646 retval = ptm_driver->open(tty, filp);
2653 down(&allocated_ptys_lock);
2654 idr_remove(&allocated_ptys, index);
2655 up(&allocated_ptys_lock);
2661 * tty_release - vfs callback for close
2662 * @inode: inode of tty
2663 * @filp: file pointer for handle to tty
2665 * Called the last time each file handle is closed that references
2666 * this tty. There may however be several such references.
2669 * Takes bkl. See release_dev
2672 static int tty_release(struct inode * inode, struct file * filp)
2681 * tty_poll - check tty status
2682 * @filp: file being polled
2683 * @wait: poll wait structures to update
2685 * Call the line discipline polling method to obtain the poll
2686 * status of the device.
2688 * Locking: locks called line discipline but ldisc poll method
2689 * may be re-entered freely by other callers.
2692 static unsigned int tty_poll(struct file * filp, poll_table * wait)
2694 struct tty_struct * tty;
2695 struct tty_ldisc *ld;
2698 tty = (struct tty_struct *)filp->private_data;
2699 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_poll"))
2702 ld = tty_ldisc_ref_wait(tty);
2704 ret = (ld->poll)(tty, filp, wait);
2705 tty_ldisc_deref(ld);
2709 static int tty_fasync(int fd, struct file * filp, int on)
2711 struct tty_struct * tty;
2714 tty = (struct tty_struct *)filp->private_data;
2715 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_fasync"))
2718 retval = fasync_helper(fd, filp, on, &tty->fasync);
2723 if (!waitqueue_active(&tty->read_wait))
2724 tty->minimum_to_wake = 1;
2725 retval = f_setown(filp, (-tty->pgrp) ? : current->pid, 0);
2729 if (!tty->fasync && !waitqueue_active(&tty->read_wait))
2730 tty->minimum_to_wake = N_TTY_BUF_SIZE;
2736 * tiocsti - fake input character
2737 * @tty: tty to fake input into
2738 * @p: pointer to character
2740 * Fake input to a tty device. Does the neccessary locking and
2743 * FIXME: does not honour flow control ??
2746 * Called functions take tty_ldisc_lock
2747 * current->signal->tty check is safe without locks
2749 * FIXME: may race normal receive processing
2752 static int tiocsti(struct tty_struct *tty, char __user *p)
2755 struct tty_ldisc *ld;
2757 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2759 if (get_user(ch, p))
2761 ld = tty_ldisc_ref_wait(tty);
2762 ld->receive_buf(tty, &ch, &mbz, 1);
2763 tty_ldisc_deref(ld);
2768 * tiocgwinsz - implement window query ioctl
2770 * @arg: user buffer for result
2772 * Copies the kernel idea of the window size into the user buffer.
2774 * Locking: tty->termios_mutex is taken to ensure the winsize data
2778 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user * arg)
2782 mutex_lock(&tty->termios_mutex);
2783 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2784 mutex_unlock(&tty->termios_mutex);
2786 return err ? -EFAULT: 0;
2790 * tiocswinsz - implement window size set ioctl
2792 * @arg: user buffer for result
2794 * Copies the user idea of the window size to the kernel. Traditionally
2795 * this is just advisory information but for the Linux console it
2796 * actually has driver level meaning and triggers a VC resize.
2799 * Called function use the console_sem is used to ensure we do
2800 * not try and resize the console twice at once.
2801 * The tty->termios_mutex is used to ensure we don't double
2802 * resize and get confused. Lock order - tty->termios_mutex before
2806 static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty,
2807 struct winsize __user * arg)
2809 struct winsize tmp_ws;
2811 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2814 mutex_lock(&tty->termios_mutex);
2815 if (!memcmp(&tmp_ws, &tty->winsize, sizeof(*arg)))
2819 if (tty->driver->type == TTY_DRIVER_TYPE_CONSOLE) {
2820 if (vc_lock_resize(tty->driver_data, tmp_ws.ws_col,
2822 mutex_unlock(&tty->termios_mutex);
2828 kill_pg(tty->pgrp, SIGWINCH, 1);
2829 if ((real_tty->pgrp != tty->pgrp) && (real_tty->pgrp > 0))
2830 kill_pg(real_tty->pgrp, SIGWINCH, 1);
2831 tty->winsize = tmp_ws;
2832 real_tty->winsize = tmp_ws;
2834 mutex_unlock(&tty->termios_mutex);
2839 * tioccons - allow admin to move logical console
2840 * @file: the file to become console
2842 * Allow the adminstrator to move the redirected console device
2844 * Locking: uses redirect_lock to guard the redirect information
2847 static int tioccons(struct file *file)
2849 if (!capable(CAP_SYS_ADMIN))
2851 if (file->f_op->write == redirected_tty_write) {
2853 spin_lock(&redirect_lock);
2856 spin_unlock(&redirect_lock);
2861 spin_lock(&redirect_lock);
2863 spin_unlock(&redirect_lock);
2868 spin_unlock(&redirect_lock);
2873 * fionbio - non blocking ioctl
2874 * @file: file to set blocking value
2875 * @p: user parameter
2877 * Historical tty interfaces had a blocking control ioctl before
2878 * the generic functionality existed. This piece of history is preserved
2879 * in the expected tty API of posix OS's.
2881 * Locking: none, the open fle handle ensures it won't go away.
2884 static int fionbio(struct file *file, int __user *p)
2888 if (get_user(nonblock, p))
2892 file->f_flags |= O_NONBLOCK;
2894 file->f_flags &= ~O_NONBLOCK;
2899 * tiocsctty - set controlling tty
2900 * @tty: tty structure
2901 * @arg: user argument
2903 * This ioctl is used to manage job control. It permits a session
2904 * leader to set this tty as the controlling tty for the session.
2907 * Takes tty_mutex() to protect tty instance
2908 * Takes tasklist_lock internally to walk sessions
2909 * Takes ->siglock() when updating signal->tty
2912 static int tiocsctty(struct tty_struct *tty, int arg)
2915 if (current->signal->leader &&
2916 (process_session(current) == tty->session))
2919 mutex_lock(&tty_mutex);
2921 * The process must be a session leader and
2922 * not have a controlling tty already.
2924 if (!current->signal->leader || current->signal->tty) {
2929 if (tty->session > 0) {
2931 * This tty is already the controlling
2932 * tty for another session group!
2934 if ((arg == 1) && capable(CAP_SYS_ADMIN)) {
2938 read_lock(&tasklist_lock);
2939 session_clear_tty(tty->session);
2940 read_unlock(&tasklist_lock);
2946 proc_set_tty(current, tty);
2948 mutex_unlock(&tty_mutex);
2953 * tiocgpgrp - get process group
2954 * @tty: tty passed by user
2955 * @real_tty: tty side of the tty pased by the user if a pty else the tty
2958 * Obtain the process group of the tty. If there is no process group
2961 * Locking: none. Reference to current->signal->tty is safe.
2964 static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2967 * (tty == real_tty) is a cheap way of
2968 * testing if the tty is NOT a master pty.
2970 if (tty == real_tty && current->signal->tty != real_tty)
2972 return put_user(real_tty->pgrp, p);
2976 * tiocspgrp - attempt to set process group
2977 * @tty: tty passed by user
2978 * @real_tty: tty side device matching tty passed by user
2981 * Set the process group of the tty to the session passed. Only
2982 * permitted where the tty session is our session.
2987 static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2990 int retval = tty_check_change(real_tty);
2996 if (!current->signal->tty ||
2997 (current->signal->tty != real_tty) ||
2998 (real_tty->session != process_session(current)))
3000 if (get_user(pgrp, p))
3004 if (session_of_pgrp(pgrp) != process_session(current))
3006 real_tty->pgrp = pgrp;
3011 * tiocgsid - get session id
3012 * @tty: tty passed by user
3013 * @real_tty: tty side of the tty pased by the user if a pty else the tty
3014 * @p: pointer to returned session id
3016 * Obtain the session id of the tty. If there is no session
3019 * Locking: none. Reference to current->signal->tty is safe.
3022 static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
3025 * (tty == real_tty) is a cheap way of
3026 * testing if the tty is NOT a master pty.
3028 if (tty == real_tty && current->signal->tty != real_tty)
3030 if (real_tty->session <= 0)
3032 return put_user(real_tty->session, p);
3036 * tiocsetd - set line discipline
3038 * @p: pointer to user data
3040 * Set the line discipline according to user request.
3042 * Locking: see tty_set_ldisc, this function is just a helper
3045 static int tiocsetd(struct tty_struct *tty, int __user *p)
3049 if (get_user(ldisc, p))
3051 return tty_set_ldisc(tty, ldisc);
3055 * send_break - performed time break
3056 * @tty: device to break on
3057 * @duration: timeout in mS
3059 * Perform a timed break on hardware that lacks its own driver level
3060 * timed break functionality.
3063 * atomic_write_lock serializes
3067 static int send_break(struct tty_struct *tty, unsigned int duration)
3069 if (mutex_lock_interruptible(&tty->atomic_write_lock))
3071 tty->driver->break_ctl(tty, -1);
3072 if (!signal_pending(current)) {
3073 msleep_interruptible(duration);
3075 tty->driver->break_ctl(tty, 0);
3076 mutex_unlock(&tty->atomic_write_lock);
3077 if (signal_pending(current))
3083 * tiocmget - get modem status
3085 * @file: user file pointer
3086 * @p: pointer to result
3088 * Obtain the modem status bits from the tty driver if the feature
3089 * is supported. Return -EINVAL if it is not available.
3091 * Locking: none (up to the driver)
3094 static int tty_tiocmget(struct tty_struct *tty, struct file *file, int __user *p)
3096 int retval = -EINVAL;
3098 if (tty->driver->tiocmget) {
3099 retval = tty->driver->tiocmget(tty, file);
3102 retval = put_user(retval, p);
3108 * tiocmset - set modem status
3110 * @file: user file pointer
3111 * @cmd: command - clear bits, set bits or set all
3112 * @p: pointer to desired bits
3114 * Set the modem status bits from the tty driver if the feature
3115 * is supported. Return -EINVAL if it is not available.
3117 * Locking: none (up to the driver)
3120 static int tty_tiocmset(struct tty_struct *tty, struct file *file, unsigned int cmd,
3123 int retval = -EINVAL;
3125 if (tty->driver->tiocmset) {
3126 unsigned int set, clear, val;
3128 retval = get_user(val, p);
3146 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
3147 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
3149 retval = tty->driver->tiocmset(tty, file, set, clear);
3155 * Split this up, as gcc can choke on it otherwise..
3157 int tty_ioctl(struct inode * inode, struct file * file,
3158 unsigned int cmd, unsigned long arg)
3160 struct tty_struct *tty, *real_tty;
3161 void __user *p = (void __user *)arg;
3163 struct tty_ldisc *ld;
3165 tty = (struct tty_struct *)file->private_data;
3166 if (tty_paranoia_check(tty, inode, "tty_ioctl"))
3169 /* CHECKME: is this safe as one end closes ? */
3172 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
3173 tty->driver->subtype == PTY_TYPE_MASTER)
3174 real_tty = tty->link;
3177 * Break handling by driver
3179 if (!tty->driver->break_ctl) {
3183 if (tty->driver->ioctl)
3184 return tty->driver->ioctl(tty, file, cmd, arg);
3187 /* These two ioctl's always return success; even if */
3188 /* the driver doesn't support them. */
3191 if (!tty->driver->ioctl)
3193 retval = tty->driver->ioctl(tty, file, cmd, arg);
3194 if (retval == -ENOIOCTLCMD)
3201 * Factor out some common prep work
3209 retval = tty_check_change(tty);
3212 if (cmd != TIOCCBRK) {
3213 tty_wait_until_sent(tty, 0);
3214 if (signal_pending(current))
3222 return tiocsti(tty, p);
3224 return tiocgwinsz(tty, p);
3226 return tiocswinsz(tty, real_tty, p);
3228 return real_tty!=tty ? -EINVAL : tioccons(file);
3230 return fionbio(file, p);
3232 set_bit(TTY_EXCLUSIVE, &tty->flags);
3235 clear_bit(TTY_EXCLUSIVE, &tty->flags);
3238 if (current->signal->tty != tty)
3240 if (current->signal->leader)
3241 disassociate_ctty(0);
3242 proc_clear_tty(current);
3245 return tiocsctty(tty, arg);
3247 return tiocgpgrp(tty, real_tty, p);
3249 return tiocspgrp(tty, real_tty, p);
3251 return tiocgsid(tty, real_tty, p);
3253 /* FIXME: check this is ok */
3254 return put_user(tty->ldisc.num, (int __user *)p);
3256 return tiocsetd(tty, p);
3259 return tioclinux(tty, arg);
3264 case TIOCSBRK: /* Turn break on, unconditionally */
3265 tty->driver->break_ctl(tty, -1);
3268 case TIOCCBRK: /* Turn break off, unconditionally */
3269 tty->driver->break_ctl(tty, 0);
3271 case TCSBRK: /* SVID version: non-zero arg --> no break */
3272 /* non-zero arg means wait for all output data
3273 * to be sent (performed above) but don't send break.
3274 * This is used by the tcdrain() termios function.
3277 return send_break(tty, 250);
3279 case TCSBRKP: /* support for POSIX tcsendbreak() */
3280 return send_break(tty, arg ? arg*100 : 250);
3283 return tty_tiocmget(tty, file, p);
3288 return tty_tiocmset(tty, file, cmd, p);
3290 if (tty->driver->ioctl) {
3291 retval = (tty->driver->ioctl)(tty, file, cmd, arg);
3292 if (retval != -ENOIOCTLCMD)
3295 ld = tty_ldisc_ref_wait(tty);
3298 retval = ld->ioctl(tty, file, cmd, arg);
3299 if (retval == -ENOIOCTLCMD)
3302 tty_ldisc_deref(ld);
3308 * This implements the "Secure Attention Key" --- the idea is to
3309 * prevent trojan horses by killing all processes associated with this
3310 * tty when the user hits the "Secure Attention Key". Required for
3311 * super-paranoid applications --- see the Orange Book for more details.
3313 * This code could be nicer; ideally it should send a HUP, wait a few
3314 * seconds, then send a INT, and then a KILL signal. But you then
3315 * have to coordinate with the init process, since all processes associated
3316 * with the current tty must be dead before the new getty is allowed
3319 * Now, if it would be correct ;-/ The current code has a nasty hole -
3320 * it doesn't catch files in flight. We may send the descriptor to ourselves
3321 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
3323 * Nasty bug: do_SAK is being called in interrupt context. This can
3324 * deadlock. We punt it up to process context. AKPM - 16Mar2001
3326 void __do_SAK(struct tty_struct *tty)
3331 struct task_struct *g, *p;
3335 struct fdtable *fdt;
3339 session = tty->session;
3341 tty_ldisc_flush(tty);
3343 if (tty->driver->flush_buffer)
3344 tty->driver->flush_buffer(tty);
3346 read_lock(&tasklist_lock);
3347 /* Kill the entire session */
3348 do_each_task_pid(session, PIDTYPE_SID, p) {
3349 printk(KERN_NOTICE "SAK: killed process %d"
3350 " (%s): process_session(p)==tty->session\n",
3352 send_sig(SIGKILL, p, 1);
3353 } while_each_task_pid(session, PIDTYPE_SID, p);
3354 /* Now kill any processes that happen to have the
3357 do_each_thread(g, p) {
3358 if (p->signal->tty == tty) {
3359 printk(KERN_NOTICE "SAK: killed process %d"
3360 " (%s): process_session(p)==tty->session\n",
3362 send_sig(SIGKILL, p, 1);
3368 * We don't take a ref to the file, so we must
3369 * hold ->file_lock instead.
3371 spin_lock(&p->files->file_lock);
3372 fdt = files_fdtable(p->files);
3373 for (i=0; i < fdt->max_fds; i++) {
3374 filp = fcheck_files(p->files, i);
3377 if (filp->f_op->read == tty_read &&
3378 filp->private_data == tty) {
3379 printk(KERN_NOTICE "SAK: killed process %d"
3380 " (%s): fd#%d opened to the tty\n",
3381 p->pid, p->comm, i);
3382 force_sig(SIGKILL, p);
3386 spin_unlock(&p->files->file_lock);
3389 } while_each_thread(g, p);
3390 read_unlock(&tasklist_lock);
3394 static void do_SAK_work(struct work_struct *work)
3396 struct tty_struct *tty =
3397 container_of(work, struct tty_struct, SAK_work);
3402 * The tq handling here is a little racy - tty->SAK_work may already be queued.
3403 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
3404 * the values which we write to it will be identical to the values which it
3405 * already has. --akpm
3407 void do_SAK(struct tty_struct *tty)
3411 PREPARE_WORK(&tty->SAK_work, do_SAK_work);
3412 schedule_work(&tty->SAK_work);
3415 EXPORT_SYMBOL(do_SAK);
3419 * @work: tty structure passed from work queue.
3421 * This routine is called out of the software interrupt to flush data
3422 * from the buffer chain to the line discipline.
3424 * Locking: holds tty->buf.lock to guard buffer list. Drops the lock
3425 * while invoking the line discipline receive_buf method. The
3426 * receive_buf method is single threaded for each tty instance.
3429 static void flush_to_ldisc(struct work_struct *work)
3431 struct tty_struct *tty =
3432 container_of(work, struct tty_struct, buf.work.work);
3433 unsigned long flags;
3434 struct tty_ldisc *disc;
3435 struct tty_buffer *tbuf, *head;
3437 unsigned char *flag_buf;
3439 disc = tty_ldisc_ref(tty);
3440 if (disc == NULL) /* !TTY_LDISC */
3443 spin_lock_irqsave(&tty->buf.lock, flags);
3444 head = tty->buf.head;
3446 tty->buf.head = NULL;
3448 int count = head->commit - head->read;
3450 if (head->next == NULL)
3454 tty_buffer_free(tty, tbuf);
3457 if (!tty->receive_room) {
3458 schedule_delayed_work(&tty->buf.work, 1);
3461 if (count > tty->receive_room)
3462 count = tty->receive_room;
3463 char_buf = head->char_buf_ptr + head->read;
3464 flag_buf = head->flag_buf_ptr + head->read;
3465 head->read += count;
3466 spin_unlock_irqrestore(&tty->buf.lock, flags);
3467 disc->receive_buf(tty, char_buf, flag_buf, count);
3468 spin_lock_irqsave(&tty->buf.lock, flags);
3470 tty->buf.head = head;
3472 spin_unlock_irqrestore(&tty->buf.lock, flags);
3474 tty_ldisc_deref(disc);
3478 * tty_flip_buffer_push - terminal
3481 * Queue a push of the terminal flip buffers to the line discipline. This
3482 * function must not be called from IRQ context if tty->low_latency is set.
3484 * In the event of the queue being busy for flipping the work will be
3485 * held off and retried later.
3487 * Locking: tty buffer lock. Driver locks in low latency mode.
3490 void tty_flip_buffer_push(struct tty_struct *tty)
3492 unsigned long flags;
3493 spin_lock_irqsave(&tty->buf.lock, flags);
3494 if (tty->buf.tail != NULL)
3495 tty->buf.tail->commit = tty->buf.tail->used;
3496 spin_unlock_irqrestore(&tty->buf.lock, flags);
3498 if (tty->low_latency)
3499 flush_to_ldisc(&tty->buf.work.work);
3501 schedule_delayed_work(&tty->buf.work, 1);
3504 EXPORT_SYMBOL(tty_flip_buffer_push);
3508 * initialize_tty_struct
3509 * @tty: tty to initialize
3511 * This subroutine initializes a tty structure that has been newly
3514 * Locking: none - tty in question must not be exposed at this point
3517 static void initialize_tty_struct(struct tty_struct *tty)
3519 memset(tty, 0, sizeof(struct tty_struct));
3520 tty->magic = TTY_MAGIC;
3521 tty_ldisc_assign(tty, tty_ldisc_get(N_TTY));
3523 tty->overrun_time = jiffies;
3524 tty->buf.head = tty->buf.tail = NULL;
3525 tty_buffer_init(tty);
3526 INIT_DELAYED_WORK(&tty->buf.work, flush_to_ldisc);
3527 init_MUTEX(&tty->buf.pty_sem);
3528 mutex_init(&tty->termios_mutex);
3529 init_waitqueue_head(&tty->write_wait);
3530 init_waitqueue_head(&tty->read_wait);
3531 INIT_WORK(&tty->hangup_work, do_tty_hangup);
3532 mutex_init(&tty->atomic_read_lock);
3533 mutex_init(&tty->atomic_write_lock);
3534 spin_lock_init(&tty->read_lock);
3535 INIT_LIST_HEAD(&tty->tty_files);
3536 INIT_WORK(&tty->SAK_work, NULL);
3540 * The default put_char routine if the driver did not define one.
3543 static void tty_default_put_char(struct tty_struct *tty, unsigned char ch)
3545 tty->driver->write(tty, &ch, 1);
3548 static struct class *tty_class;
3551 * tty_register_device - register a tty device
3552 * @driver: the tty driver that describes the tty device
3553 * @index: the index in the tty driver for this tty device
3554 * @device: a struct device that is associated with this tty device.
3555 * This field is optional, if there is no known struct device
3556 * for this tty device it can be set to NULL safely.
3558 * Returns a pointer to the struct device for this tty device
3559 * (or ERR_PTR(-EFOO) on error).
3561 * This call is required to be made to register an individual tty device
3562 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3563 * that bit is not set, this function should not be called by a tty
3569 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
3570 struct device *device)
3573 dev_t dev = MKDEV(driver->major, driver->minor_start) + index;
3575 if (index >= driver->num) {
3576 printk(KERN_ERR "Attempt to register invalid tty line number "
3578 return ERR_PTR(-EINVAL);
3581 if (driver->type == TTY_DRIVER_TYPE_PTY)
3582 pty_line_name(driver, index, name);
3584 tty_line_name(driver, index, name);
3586 return device_create(tty_class, device, dev, name);
3590 * tty_unregister_device - unregister a tty device
3591 * @driver: the tty driver that describes the tty device
3592 * @index: the index in the tty driver for this tty device
3594 * If a tty device is registered with a call to tty_register_device() then
3595 * this function must be called when the tty device is gone.
3600 void tty_unregister_device(struct tty_driver *driver, unsigned index)
3602 device_destroy(tty_class, MKDEV(driver->major, driver->minor_start) + index);
3605 EXPORT_SYMBOL(tty_register_device);
3606 EXPORT_SYMBOL(tty_unregister_device);
3608 struct tty_driver *alloc_tty_driver(int lines)
3610 struct tty_driver *driver;
3612 driver = kmalloc(sizeof(struct tty_driver), GFP_KERNEL);
3614 memset(driver, 0, sizeof(struct tty_driver));
3615 driver->magic = TTY_DRIVER_MAGIC;
3616 driver->num = lines;
3617 /* later we'll move allocation of tables here */
3622 void put_tty_driver(struct tty_driver *driver)
3627 void tty_set_operations(struct tty_driver *driver,
3628 const struct tty_operations *op)
3630 driver->open = op->open;
3631 driver->close = op->close;
3632 driver->write = op->write;
3633 driver->put_char = op->put_char;
3634 driver->flush_chars = op->flush_chars;
3635 driver->write_room = op->write_room;
3636 driver->chars_in_buffer = op->chars_in_buffer;
3637 driver->ioctl = op->ioctl;
3638 driver->set_termios = op->set_termios;
3639 driver->throttle = op->throttle;
3640 driver->unthrottle = op->unthrottle;
3641 driver->stop = op->stop;
3642 driver->start = op->start;
3643 driver->hangup = op->hangup;
3644 driver->break_ctl = op->break_ctl;
3645 driver->flush_buffer = op->flush_buffer;
3646 driver->set_ldisc = op->set_ldisc;
3647 driver->wait_until_sent = op->wait_until_sent;
3648 driver->send_xchar = op->send_xchar;
3649 driver->read_proc = op->read_proc;
3650 driver->write_proc = op->write_proc;
3651 driver->tiocmget = op->tiocmget;
3652 driver->tiocmset = op->tiocmset;
3656 EXPORT_SYMBOL(alloc_tty_driver);
3657 EXPORT_SYMBOL(put_tty_driver);
3658 EXPORT_SYMBOL(tty_set_operations);
3661 * Called by a tty driver to register itself.
3663 int tty_register_driver(struct tty_driver *driver)
3670 if (driver->flags & TTY_DRIVER_INSTALLED)
3673 if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
3674 p = kmalloc(driver->num * 3 * sizeof(void *), GFP_KERNEL);
3677 memset(p, 0, driver->num * 3 * sizeof(void *));
3680 if (!driver->major) {
3681 error = alloc_chrdev_region(&dev, driver->minor_start, driver->num,
3682 (char*)driver->name);
3684 driver->major = MAJOR(dev);
3685 driver->minor_start = MINOR(dev);
3688 dev = MKDEV(driver->major, driver->minor_start);
3689 error = register_chrdev_region(dev, driver->num,
3690 (char*)driver->name);
3698 driver->ttys = (struct tty_struct **)p;
3699 driver->termios = (struct ktermios **)(p + driver->num);
3700 driver->termios_locked = (struct ktermios **)(p + driver->num * 2);
3702 driver->ttys = NULL;
3703 driver->termios = NULL;
3704 driver->termios_locked = NULL;
3707 cdev_init(&driver->cdev, &tty_fops);
3708 driver->cdev.owner = driver->owner;
3709 error = cdev_add(&driver->cdev, dev, driver->num);
3711 unregister_chrdev_region(dev, driver->num);
3712 driver->ttys = NULL;
3713 driver->termios = driver->termios_locked = NULL;
3718 if (!driver->put_char)
3719 driver->put_char = tty_default_put_char;
3721 list_add(&driver->tty_drivers, &tty_drivers);
3723 if ( !(driver->flags & TTY_DRIVER_DYNAMIC_DEV) ) {
3724 for(i = 0; i < driver->num; i++)
3725 tty_register_device(driver, i, NULL);
3727 proc_tty_register_driver(driver);
3731 EXPORT_SYMBOL(tty_register_driver);
3734 * Called by a tty driver to unregister itself.
3736 int tty_unregister_driver(struct tty_driver *driver)
3739 struct ktermios *tp;
3742 if (driver->refcount)
3745 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3748 list_del(&driver->tty_drivers);
3751 * Free the termios and termios_locked structures because
3752 * we don't want to get memory leaks when modular tty
3753 * drivers are removed from the kernel.
3755 for (i = 0; i < driver->num; i++) {
3756 tp = driver->termios[i];
3758 driver->termios[i] = NULL;
3761 tp = driver->termios_locked[i];
3763 driver->termios_locked[i] = NULL;
3766 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3767 tty_unregister_device(driver, i);
3770 proc_tty_unregister_driver(driver);
3771 driver->ttys = NULL;
3772 driver->termios = driver->termios_locked = NULL;
3774 cdev_del(&driver->cdev);
3777 EXPORT_SYMBOL(tty_unregister_driver);
3779 dev_t tty_devnum(struct tty_struct *tty)
3781 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3783 EXPORT_SYMBOL(tty_devnum);
3785 void proc_clear_tty(struct task_struct *p)
3787 spin_lock_irq(&p->sighand->siglock);
3788 p->signal->tty = NULL;
3789 spin_unlock_irq(&p->sighand->siglock);
3791 EXPORT_SYMBOL(proc_clear_tty);
3793 void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3796 tty->session = process_session(tsk);
3797 tty->pgrp = process_group(tsk);
3799 tsk->signal->tty = tty;
3800 tsk->signal->tty_old_pgrp = 0;
3803 void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3805 spin_lock_irq(&tsk->sighand->siglock);
3806 __proc_set_tty(tsk, tty);
3807 spin_unlock_irq(&tsk->sighand->siglock);
3810 struct tty_struct *get_current_tty(void)
3812 struct tty_struct *tty;
3813 WARN_ON_ONCE(!mutex_is_locked(&tty_mutex));
3814 tty = current->signal->tty;
3816 * session->tty can be changed/cleared from under us, make sure we
3817 * issue the load. The obtained pointer, when not NULL, is valid as
3818 * long as we hold tty_mutex.
3823 EXPORT_SYMBOL_GPL(get_current_tty);
3826 * Initialize the console device. This is called *early*, so
3827 * we can't necessarily depend on lots of kernel help here.
3828 * Just do some early initializations, and do the complex setup
3831 void __init console_init(void)
3835 /* Setup the default TTY line discipline. */
3836 (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY);
3839 * set up the console device so that later boot sequences can
3840 * inform about problems etc..
3842 #ifdef CONFIG_EARLY_PRINTK
3843 disable_early_printk();
3845 call = __con_initcall_start;
3846 while (call < __con_initcall_end) {
3853 extern int vty_init(void);
3856 static int __init tty_class_init(void)
3858 tty_class = class_create(THIS_MODULE, "tty");
3859 if (IS_ERR(tty_class))
3860 return PTR_ERR(tty_class);
3864 postcore_initcall(tty_class_init);
3866 /* 3/2004 jmc: why do these devices exist? */
3868 static struct cdev tty_cdev, console_cdev;
3869 #ifdef CONFIG_UNIX98_PTYS
3870 static struct cdev ptmx_cdev;
3873 static struct cdev vc0_cdev;
3877 * Ok, now we can initialize the rest of the tty devices and can count
3878 * on memory allocations, interrupts etc..
3880 static int __init tty_init(void)
3882 cdev_init(&tty_cdev, &tty_fops);
3883 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3884 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3885 panic("Couldn't register /dev/tty driver\n");
3886 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), "tty");
3888 cdev_init(&console_cdev, &console_fops);
3889 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3890 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3891 panic("Couldn't register /dev/console driver\n");
3892 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 1), "console");
3894 #ifdef CONFIG_UNIX98_PTYS
3895 cdev_init(&ptmx_cdev, &ptmx_fops);
3896 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
3897 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
3898 panic("Couldn't register /dev/ptmx driver\n");
3899 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), "ptmx");
3903 cdev_init(&vc0_cdev, &console_fops);
3904 if (cdev_add(&vc0_cdev, MKDEV(TTY_MAJOR, 0), 1) ||
3905 register_chrdev_region(MKDEV(TTY_MAJOR, 0), 1, "/dev/vc/0") < 0)
3906 panic("Couldn't register /dev/tty0 driver\n");
3907 device_create(tty_class, NULL, MKDEV(TTY_MAJOR, 0), "tty0");
3913 module_init(tty_init);