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);
154 static int tty_fasync(int fd, struct file * filp, int on);
155 static void release_tty(struct tty_struct *tty, int idx);
156 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
159 * alloc_tty_struct - allocate a tty object
161 * Return a new empty tty structure. The data fields have not
162 * been initialized in any way but has been zeroed
167 static struct tty_struct *alloc_tty_struct(void)
169 return kzalloc(sizeof(struct tty_struct), GFP_KERNEL);
172 static void tty_buffer_free_all(struct tty_struct *);
175 * free_tty_struct - free a disused tty
176 * @tty: tty struct to free
178 * Free the write buffers, tty queue and tty memory itself.
180 * Locking: none. Must be called after tty is definitely unused
183 static inline void free_tty_struct(struct tty_struct *tty)
185 kfree(tty->write_buf);
186 tty_buffer_free_all(tty);
190 #define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base)
193 * tty_name - return tty naming
194 * @tty: tty structure
195 * @buf: buffer for output
197 * Convert a tty structure into a name. The name reflects the kernel
198 * naming policy and if udev is in use may not reflect user space
203 char *tty_name(struct tty_struct *tty, char *buf)
205 if (!tty) /* Hmm. NULL pointer. That's fun. */
206 strcpy(buf, "NULL tty");
208 strcpy(buf, tty->name);
212 EXPORT_SYMBOL(tty_name);
214 int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
217 #ifdef TTY_PARANOIA_CHECK
220 "null TTY for (%d:%d) in %s\n",
221 imajor(inode), iminor(inode), routine);
224 if (tty->magic != TTY_MAGIC) {
226 "bad magic number for tty struct (%d:%d) in %s\n",
227 imajor(inode), iminor(inode), routine);
234 static int check_tty_count(struct tty_struct *tty, const char *routine)
236 #ifdef CHECK_TTY_COUNT
241 list_for_each(p, &tty->tty_files) {
245 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
246 tty->driver->subtype == PTY_TYPE_SLAVE &&
247 tty->link && tty->link->count)
249 if (tty->count != count) {
250 printk(KERN_WARNING "Warning: dev (%s) tty->count(%d) "
251 "!= #fd's(%d) in %s\n",
252 tty->name, tty->count, count, routine);
260 * Tty buffer allocation management
264 * tty_buffer_free_all - free buffers used by a tty
265 * @tty: tty to free from
267 * Remove all the buffers pending on a tty whether queued with data
268 * or in the free ring. Must be called when the tty is no longer in use
273 static void tty_buffer_free_all(struct tty_struct *tty)
275 struct tty_buffer *thead;
276 while((thead = tty->buf.head) != NULL) {
277 tty->buf.head = thead->next;
280 while((thead = tty->buf.free) != NULL) {
281 tty->buf.free = thead->next;
284 tty->buf.tail = NULL;
285 tty->buf.memory_used = 0;
289 * tty_buffer_init - prepare a tty buffer structure
290 * @tty: tty to initialise
292 * Set up the initial state of the buffer management for a tty device.
293 * Must be called before the other tty buffer functions are used.
298 static void tty_buffer_init(struct tty_struct *tty)
300 spin_lock_init(&tty->buf.lock);
301 tty->buf.head = NULL;
302 tty->buf.tail = NULL;
303 tty->buf.free = NULL;
304 tty->buf.memory_used = 0;
308 * tty_buffer_alloc - allocate a tty buffer
310 * @size: desired size (characters)
312 * Allocate a new tty buffer to hold the desired number of characters.
313 * Return NULL if out of memory or the allocation would exceed the
316 * Locking: Caller must hold tty->buf.lock
319 static struct tty_buffer *tty_buffer_alloc(struct tty_struct *tty, size_t size)
321 struct tty_buffer *p;
323 if (tty->buf.memory_used + size > 65536)
325 p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC);
333 p->char_buf_ptr = (char *)(p->data);
334 p->flag_buf_ptr = (unsigned char *)p->char_buf_ptr + size;
335 tty->buf.memory_used += size;
340 * tty_buffer_free - free a tty buffer
341 * @tty: tty owning the buffer
342 * @b: the buffer to free
344 * Free a tty buffer, or add it to the free list according to our
347 * Locking: Caller must hold tty->buf.lock
350 static void tty_buffer_free(struct tty_struct *tty, struct tty_buffer *b)
352 /* Dumb strategy for now - should keep some stats */
353 tty->buf.memory_used -= b->size;
354 WARN_ON(tty->buf.memory_used < 0);
359 b->next = tty->buf.free;
365 * tty_buffer_find - find a free tty buffer
366 * @tty: tty owning the buffer
367 * @size: characters wanted
369 * Locate an existing suitable tty buffer or if we are lacking one then
370 * allocate a new one. We round our buffers off in 256 character chunks
371 * to get better allocation behaviour.
373 * Locking: Caller must hold tty->buf.lock
376 static struct tty_buffer *tty_buffer_find(struct tty_struct *tty, size_t size)
378 struct tty_buffer **tbh = &tty->buf.free;
379 while((*tbh) != NULL) {
380 struct tty_buffer *t = *tbh;
381 if(t->size >= size) {
387 tty->buf.memory_used += t->size;
390 tbh = &((*tbh)->next);
392 /* Round the buffer size out */
393 size = (size + 0xFF) & ~ 0xFF;
394 return tty_buffer_alloc(tty, size);
395 /* Should possibly check if this fails for the largest buffer we
396 have queued and recycle that ? */
400 * tty_buffer_request_room - grow tty buffer if needed
401 * @tty: tty structure
402 * @size: size desired
404 * Make at least size bytes of linear space available for the tty
405 * buffer. If we fail return the size we managed to find.
407 * Locking: Takes tty->buf.lock
409 int tty_buffer_request_room(struct tty_struct *tty, size_t size)
411 struct tty_buffer *b, *n;
415 spin_lock_irqsave(&tty->buf.lock, flags);
417 /* OPTIMISATION: We could keep a per tty "zero" sized buffer to
418 remove this conditional if its worth it. This would be invisible
420 if ((b = tty->buf.tail) != NULL)
421 left = b->size - b->used;
426 /* This is the slow path - looking for new buffers to use */
427 if ((n = tty_buffer_find(tty, size)) != NULL) {
438 spin_unlock_irqrestore(&tty->buf.lock, flags);
441 EXPORT_SYMBOL_GPL(tty_buffer_request_room);
444 * tty_insert_flip_string - Add characters to the tty buffer
445 * @tty: tty structure
449 * Queue a series of bytes to the tty buffering. All the characters
450 * passed are marked as without error. Returns the number added.
452 * Locking: Called functions may take tty->buf.lock
455 int tty_insert_flip_string(struct tty_struct *tty, const unsigned char *chars,
460 int space = tty_buffer_request_room(tty, size - copied);
461 struct tty_buffer *tb = tty->buf.tail;
462 /* If there is no space then tb may be NULL */
463 if(unlikely(space == 0))
465 memcpy(tb->char_buf_ptr + tb->used, chars, space);
466 memset(tb->flag_buf_ptr + tb->used, TTY_NORMAL, space);
470 /* There is a small chance that we need to split the data over
471 several buffers. If this is the case we must loop */
472 } while (unlikely(size > copied));
475 EXPORT_SYMBOL(tty_insert_flip_string);
478 * tty_insert_flip_string_flags - Add characters to the tty buffer
479 * @tty: tty structure
484 * Queue a series of bytes to the tty buffering. For each character
485 * the flags array indicates the status of the character. Returns the
488 * Locking: Called functions may take tty->buf.lock
491 int tty_insert_flip_string_flags(struct tty_struct *tty,
492 const unsigned char *chars, const char *flags, size_t size)
496 int space = tty_buffer_request_room(tty, size - copied);
497 struct tty_buffer *tb = tty->buf.tail;
498 /* If there is no space then tb may be NULL */
499 if(unlikely(space == 0))
501 memcpy(tb->char_buf_ptr + tb->used, chars, space);
502 memcpy(tb->flag_buf_ptr + tb->used, flags, space);
507 /* There is a small chance that we need to split the data over
508 several buffers. If this is the case we must loop */
509 } while (unlikely(size > copied));
512 EXPORT_SYMBOL(tty_insert_flip_string_flags);
515 * tty_schedule_flip - push characters to ldisc
516 * @tty: tty to push from
518 * Takes any pending buffers and transfers their ownership to the
519 * ldisc side of the queue. It then schedules those characters for
520 * processing by the line discipline.
522 * Locking: Takes tty->buf.lock
525 void tty_schedule_flip(struct tty_struct *tty)
528 spin_lock_irqsave(&tty->buf.lock, flags);
529 if (tty->buf.tail != NULL)
530 tty->buf.tail->commit = tty->buf.tail->used;
531 spin_unlock_irqrestore(&tty->buf.lock, flags);
532 schedule_delayed_work(&tty->buf.work, 1);
534 EXPORT_SYMBOL(tty_schedule_flip);
537 * tty_prepare_flip_string - make room for characters
539 * @chars: return pointer for character write area
540 * @size: desired size
542 * Prepare a block of space in the buffer for data. Returns the length
543 * available and buffer pointer to the space which is now allocated and
544 * accounted for as ready for normal characters. This is used for drivers
545 * that need their own block copy routines into the buffer. There is no
546 * guarantee the buffer is a DMA target!
548 * Locking: May call functions taking tty->buf.lock
551 int tty_prepare_flip_string(struct tty_struct *tty, unsigned char **chars, size_t size)
553 int space = tty_buffer_request_room(tty, size);
555 struct tty_buffer *tb = tty->buf.tail;
556 *chars = tb->char_buf_ptr + tb->used;
557 memset(tb->flag_buf_ptr + tb->used, TTY_NORMAL, space);
563 EXPORT_SYMBOL_GPL(tty_prepare_flip_string);
566 * tty_prepare_flip_string_flags - make room for characters
568 * @chars: return pointer for character write area
569 * @flags: return pointer for status flag 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 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_flags(struct tty_struct *tty, unsigned char **chars, char **flags, 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 *flags = tb->flag_buf_ptr + tb->used;
593 EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags);
598 * tty_set_termios_ldisc - set ldisc field
599 * @tty: tty structure
600 * @num: line discipline number
602 * This is probably overkill for real world processors but
603 * they are not on hot paths so a little discipline won't do
606 * Locking: takes termios_mutex
609 static void tty_set_termios_ldisc(struct tty_struct *tty, int num)
611 mutex_lock(&tty->termios_mutex);
612 tty->termios->c_line = num;
613 mutex_unlock(&tty->termios_mutex);
617 * This guards the refcounted line discipline lists. The lock
618 * must be taken with irqs off because there are hangup path
619 * callers who will do ldisc lookups and cannot sleep.
622 static DEFINE_SPINLOCK(tty_ldisc_lock);
623 static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_wait);
624 static struct tty_ldisc tty_ldiscs[NR_LDISCS]; /* line disc dispatch table */
627 * tty_register_ldisc - install a line discipline
628 * @disc: ldisc number
629 * @new_ldisc: pointer to the ldisc object
631 * Installs a new line discipline into the kernel. The discipline
632 * is set up as unreferenced and then made available to the kernel
633 * from this point onwards.
636 * takes tty_ldisc_lock to guard against ldisc races
639 int tty_register_ldisc(int disc, struct tty_ldisc *new_ldisc)
644 if (disc < N_TTY || disc >= NR_LDISCS)
647 spin_lock_irqsave(&tty_ldisc_lock, flags);
648 tty_ldiscs[disc] = *new_ldisc;
649 tty_ldiscs[disc].num = disc;
650 tty_ldiscs[disc].flags |= LDISC_FLAG_DEFINED;
651 tty_ldiscs[disc].refcount = 0;
652 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
656 EXPORT_SYMBOL(tty_register_ldisc);
659 * tty_unregister_ldisc - unload a line discipline
660 * @disc: ldisc number
661 * @new_ldisc: pointer to the ldisc object
663 * Remove a line discipline from the kernel providing it is not
667 * takes tty_ldisc_lock to guard against ldisc races
670 int tty_unregister_ldisc(int disc)
675 if (disc < N_TTY || disc >= NR_LDISCS)
678 spin_lock_irqsave(&tty_ldisc_lock, flags);
679 if (tty_ldiscs[disc].refcount)
682 tty_ldiscs[disc].flags &= ~LDISC_FLAG_DEFINED;
683 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
687 EXPORT_SYMBOL(tty_unregister_ldisc);
690 * tty_ldisc_get - take a reference to an ldisc
691 * @disc: ldisc number
693 * Takes a reference to a line discipline. Deals with refcounts and
694 * module locking counts. Returns NULL if the discipline is not available.
695 * Returns a pointer to the discipline and bumps the ref count if it is
699 * takes tty_ldisc_lock to guard against ldisc races
702 struct tty_ldisc *tty_ldisc_get(int disc)
705 struct tty_ldisc *ld;
707 if (disc < N_TTY || disc >= NR_LDISCS)
710 spin_lock_irqsave(&tty_ldisc_lock, flags);
712 ld = &tty_ldiscs[disc];
713 /* Check the entry is defined */
714 if(ld->flags & LDISC_FLAG_DEFINED)
716 /* If the module is being unloaded we can't use it */
717 if (!try_module_get(ld->owner))
724 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
728 EXPORT_SYMBOL_GPL(tty_ldisc_get);
731 * tty_ldisc_put - drop ldisc reference
732 * @disc: ldisc number
734 * Drop a reference to a line discipline. Manage refcounts and
735 * module usage counts
738 * takes tty_ldisc_lock to guard against ldisc races
741 void tty_ldisc_put(int disc)
743 struct tty_ldisc *ld;
746 BUG_ON(disc < N_TTY || disc >= NR_LDISCS);
748 spin_lock_irqsave(&tty_ldisc_lock, flags);
749 ld = &tty_ldiscs[disc];
750 BUG_ON(ld->refcount == 0);
752 module_put(ld->owner);
753 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
756 EXPORT_SYMBOL_GPL(tty_ldisc_put);
759 * tty_ldisc_assign - set ldisc on a tty
760 * @tty: tty to assign
761 * @ld: line discipline
763 * Install an instance of a line discipline into a tty structure. The
764 * ldisc must have a reference count above zero to ensure it remains/
765 * The tty instance refcount starts at zero.
768 * Caller must hold references
771 static void tty_ldisc_assign(struct tty_struct *tty, struct tty_ldisc *ld)
774 tty->ldisc.refcount = 0;
778 * tty_ldisc_try - internal helper
781 * Make a single attempt to grab and bump the refcount on
782 * the tty ldisc. Return 0 on failure or 1 on success. This is
783 * used to implement both the waiting and non waiting versions
786 * Locking: takes tty_ldisc_lock
789 static int tty_ldisc_try(struct tty_struct *tty)
792 struct tty_ldisc *ld;
795 spin_lock_irqsave(&tty_ldisc_lock, flags);
797 if(test_bit(TTY_LDISC, &tty->flags))
802 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
807 * tty_ldisc_ref_wait - wait for the tty ldisc
810 * Dereference the line discipline for the terminal and take a
811 * reference to it. If the line discipline is in flux then
812 * wait patiently until it changes.
814 * Note: Must not be called from an IRQ/timer context. The caller
815 * must also be careful not to hold other locks that will deadlock
816 * against a discipline change, such as an existing ldisc reference
817 * (which we check for)
819 * Locking: call functions take tty_ldisc_lock
822 struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty)
824 /* wait_event is a macro */
825 wait_event(tty_ldisc_wait, tty_ldisc_try(tty));
826 if(tty->ldisc.refcount == 0)
827 printk(KERN_ERR "tty_ldisc_ref_wait\n");
831 EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait);
834 * tty_ldisc_ref - get the tty ldisc
837 * Dereference the line discipline for the terminal and take a
838 * reference to it. If the line discipline is in flux then
839 * return NULL. Can be called from IRQ and timer functions.
841 * Locking: called functions take tty_ldisc_lock
844 struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty)
846 if(tty_ldisc_try(tty))
851 EXPORT_SYMBOL_GPL(tty_ldisc_ref);
854 * tty_ldisc_deref - free a tty ldisc reference
855 * @ld: reference to free up
857 * Undoes the effect of tty_ldisc_ref or tty_ldisc_ref_wait. May
858 * be called in IRQ context.
860 * Locking: takes tty_ldisc_lock
863 void tty_ldisc_deref(struct tty_ldisc *ld)
869 spin_lock_irqsave(&tty_ldisc_lock, flags);
870 if(ld->refcount == 0)
871 printk(KERN_ERR "tty_ldisc_deref: no references.\n");
874 if(ld->refcount == 0)
875 wake_up(&tty_ldisc_wait);
876 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
879 EXPORT_SYMBOL_GPL(tty_ldisc_deref);
882 * tty_ldisc_enable - allow ldisc use
883 * @tty: terminal to activate ldisc on
885 * Set the TTY_LDISC flag when the line discipline can be called
886 * again. Do neccessary wakeups for existing sleepers.
888 * Note: nobody should set this bit except via this function. Clearing
889 * directly is allowed.
892 static void tty_ldisc_enable(struct tty_struct *tty)
894 set_bit(TTY_LDISC, &tty->flags);
895 wake_up(&tty_ldisc_wait);
899 * tty_set_ldisc - set line discipline
900 * @tty: the terminal to set
901 * @ldisc: the line discipline
903 * Set the discipline of a tty line. Must be called from a process
906 * Locking: takes tty_ldisc_lock.
907 * called functions take termios_mutex
910 static int tty_set_ldisc(struct tty_struct *tty, int ldisc)
913 struct tty_ldisc o_ldisc;
917 struct tty_ldisc *ld;
918 struct tty_struct *o_tty;
920 if ((ldisc < N_TTY) || (ldisc >= NR_LDISCS))
925 ld = tty_ldisc_get(ldisc);
926 /* Eduardo Blanco <ejbs@cs.cs.com.uy> */
927 /* Cyrus Durgin <cider@speakeasy.org> */
929 request_module("tty-ldisc-%d", ldisc);
930 ld = tty_ldisc_get(ldisc);
936 * No more input please, we are switching. The new ldisc
937 * will update this value in the ldisc open function
940 tty->receive_room = 0;
943 * Problem: What do we do if this blocks ?
946 tty_wait_until_sent(tty, 0);
948 if (tty->ldisc.num == ldisc) {
949 tty_ldisc_put(ldisc);
953 o_ldisc = tty->ldisc;
957 * Make sure we don't change while someone holds a
958 * reference to the line discipline. The TTY_LDISC bit
959 * prevents anyone taking a reference once it is clear.
960 * We need the lock to avoid racing reference takers.
963 spin_lock_irqsave(&tty_ldisc_lock, flags);
964 if (tty->ldisc.refcount || (o_tty && o_tty->ldisc.refcount)) {
965 if(tty->ldisc.refcount) {
966 /* Free the new ldisc we grabbed. Must drop the lock
968 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
969 tty_ldisc_put(ldisc);
971 * There are several reasons we may be busy, including
972 * random momentary I/O traffic. We must therefore
973 * retry. We could distinguish between blocking ops
974 * and retries if we made tty_ldisc_wait() smarter. That
975 * is up for discussion.
977 if (wait_event_interruptible(tty_ldisc_wait, tty->ldisc.refcount == 0) < 0)
981 if(o_tty && o_tty->ldisc.refcount) {
982 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
983 tty_ldisc_put(ldisc);
984 if (wait_event_interruptible(tty_ldisc_wait, o_tty->ldisc.refcount == 0) < 0)
990 /* if the TTY_LDISC bit is set, then we are racing against another ldisc change */
992 if (!test_bit(TTY_LDISC, &tty->flags)) {
993 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
994 tty_ldisc_put(ldisc);
995 ld = tty_ldisc_ref_wait(tty);
1000 clear_bit(TTY_LDISC, &tty->flags);
1002 clear_bit(TTY_LDISC, &o_tty->flags);
1003 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
1006 * From this point on we know nobody has an ldisc
1007 * usage reference, nor can they obtain one until
1008 * we say so later on.
1011 work = cancel_delayed_work(&tty->buf.work);
1013 * Wait for ->hangup_work and ->buf.work handlers to terminate
1016 flush_scheduled_work();
1017 /* Shutdown the current discipline. */
1018 if (tty->ldisc.close)
1019 (tty->ldisc.close)(tty);
1021 /* Now set up the new line discipline. */
1022 tty_ldisc_assign(tty, ld);
1023 tty_set_termios_ldisc(tty, ldisc);
1024 if (tty->ldisc.open)
1025 retval = (tty->ldisc.open)(tty);
1027 tty_ldisc_put(ldisc);
1028 /* There is an outstanding reference here so this is safe */
1029 tty_ldisc_assign(tty, tty_ldisc_get(o_ldisc.num));
1030 tty_set_termios_ldisc(tty, tty->ldisc.num);
1031 if (tty->ldisc.open && (tty->ldisc.open(tty) < 0)) {
1032 tty_ldisc_put(o_ldisc.num);
1033 /* This driver is always present */
1034 tty_ldisc_assign(tty, tty_ldisc_get(N_TTY));
1035 tty_set_termios_ldisc(tty, N_TTY);
1036 if (tty->ldisc.open) {
1037 int r = tty->ldisc.open(tty);
1040 panic("Couldn't open N_TTY ldisc for "
1042 tty_name(tty, buf), r);
1046 /* At this point we hold a reference to the new ldisc and a
1047 a reference to the old ldisc. If we ended up flipping back
1048 to the existing ldisc we have two references to it */
1050 if (tty->ldisc.num != o_ldisc.num && tty->driver->set_ldisc)
1051 tty->driver->set_ldisc(tty);
1053 tty_ldisc_put(o_ldisc.num);
1056 * Allow ldisc referencing to occur as soon as the driver
1057 * ldisc callback completes.
1060 tty_ldisc_enable(tty);
1062 tty_ldisc_enable(o_tty);
1064 /* Restart it in case no characters kick it off. Safe if
1067 schedule_delayed_work(&tty->buf.work, 1);
1072 * get_tty_driver - find device of a tty
1073 * @dev_t: device identifier
1074 * @index: returns the index of the tty
1076 * This routine returns a tty driver structure, given a device number
1077 * and also passes back the index number.
1079 * Locking: caller must hold tty_mutex
1082 static struct tty_driver *get_tty_driver(dev_t device, int *index)
1084 struct tty_driver *p;
1086 list_for_each_entry(p, &tty_drivers, tty_drivers) {
1087 dev_t base = MKDEV(p->major, p->minor_start);
1088 if (device < base || device >= base + p->num)
1090 *index = device - base;
1097 * tty_check_change - check for POSIX terminal changes
1098 * @tty: tty to check
1100 * If we try to write to, or set the state of, a terminal and we're
1101 * not in the foreground, send a SIGTTOU. If the signal is blocked or
1102 * ignored, go ahead and perform the operation. (POSIX 7.2)
1107 int tty_check_change(struct tty_struct * tty)
1109 if (current->signal->tty != tty)
1112 printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");
1115 if (task_pgrp(current) == tty->pgrp)
1117 if (is_ignored(SIGTTOU))
1119 if (is_current_pgrp_orphaned())
1121 (void) kill_pgrp(task_pgrp(current), SIGTTOU, 1);
1122 return -ERESTARTSYS;
1125 EXPORT_SYMBOL(tty_check_change);
1127 static ssize_t hung_up_tty_read(struct file * file, char __user * buf,
1128 size_t count, loff_t *ppos)
1133 static ssize_t hung_up_tty_write(struct file * file, const char __user * buf,
1134 size_t count, loff_t *ppos)
1139 /* No kernel lock held - none needed ;) */
1140 static unsigned int hung_up_tty_poll(struct file * filp, poll_table * wait)
1142 return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM;
1145 static int hung_up_tty_ioctl(struct inode * inode, struct file * file,
1146 unsigned int cmd, unsigned long arg)
1148 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
1151 static const struct file_operations tty_fops = {
1152 .llseek = no_llseek,
1158 .release = tty_release,
1159 .fasync = tty_fasync,
1162 #ifdef CONFIG_UNIX98_PTYS
1163 static const struct file_operations ptmx_fops = {
1164 .llseek = no_llseek,
1170 .release = tty_release,
1171 .fasync = tty_fasync,
1175 static const struct file_operations console_fops = {
1176 .llseek = no_llseek,
1178 .write = redirected_tty_write,
1182 .release = tty_release,
1183 .fasync = tty_fasync,
1186 static const struct file_operations hung_up_tty_fops = {
1187 .llseek = no_llseek,
1188 .read = hung_up_tty_read,
1189 .write = hung_up_tty_write,
1190 .poll = hung_up_tty_poll,
1191 .ioctl = hung_up_tty_ioctl,
1192 .release = tty_release,
1195 static DEFINE_SPINLOCK(redirect_lock);
1196 static struct file *redirect;
1199 * tty_wakeup - request more data
1202 * Internal and external helper for wakeups of tty. This function
1203 * informs the line discipline if present that the driver is ready
1204 * to receive more output data.
1207 void tty_wakeup(struct tty_struct *tty)
1209 struct tty_ldisc *ld;
1211 if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
1212 ld = tty_ldisc_ref(tty);
1214 if(ld->write_wakeup)
1215 ld->write_wakeup(tty);
1216 tty_ldisc_deref(ld);
1219 wake_up_interruptible(&tty->write_wait);
1222 EXPORT_SYMBOL_GPL(tty_wakeup);
1225 * tty_ldisc_flush - flush line discipline queue
1228 * Flush the line discipline queue (if any) for this tty. If there
1229 * is no line discipline active this is a no-op.
1232 void tty_ldisc_flush(struct tty_struct *tty)
1234 struct tty_ldisc *ld = tty_ldisc_ref(tty);
1236 if(ld->flush_buffer)
1237 ld->flush_buffer(tty);
1238 tty_ldisc_deref(ld);
1242 EXPORT_SYMBOL_GPL(tty_ldisc_flush);
1245 * tty_reset_termios - reset terminal state
1246 * @tty: tty to reset
1248 * Restore a terminal to the driver default state
1251 static void tty_reset_termios(struct tty_struct *tty)
1253 mutex_lock(&tty->termios_mutex);
1254 *tty->termios = tty->driver->init_termios;
1255 tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
1256 tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
1257 mutex_unlock(&tty->termios_mutex);
1261 * do_tty_hangup - actual handler for hangup events
1264 * This can be called by the "eventd" kernel thread. That is process
1265 * synchronous but doesn't hold any locks, so we need to make sure we
1266 * have the appropriate locks for what we're doing.
1268 * The hangup event clears any pending redirections onto the hung up
1269 * device. It ensures future writes will error and it does the needed
1270 * line discipline hangup and signal delivery. The tty object itself
1275 * redirect lock for undoing redirection
1276 * file list lock for manipulating list of ttys
1277 * tty_ldisc_lock from called functions
1278 * termios_mutex resetting termios data
1279 * tasklist_lock to walk task list for hangup event
1280 * ->siglock to protect ->signal/->sighand
1282 static void do_tty_hangup(struct work_struct *work)
1284 struct tty_struct *tty =
1285 container_of(work, struct tty_struct, hangup_work);
1286 struct file * cons_filp = NULL;
1287 struct file *filp, *f = NULL;
1288 struct task_struct *p;
1289 struct tty_ldisc *ld;
1290 int closecount = 0, n;
1295 /* inuse_filps is protected by the single kernel lock */
1298 spin_lock(&redirect_lock);
1299 if (redirect && redirect->private_data == tty) {
1303 spin_unlock(&redirect_lock);
1305 check_tty_count(tty, "do_tty_hangup");
1307 /* This breaks for file handles being sent over AF_UNIX sockets ? */
1308 list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) {
1309 if (filp->f_op->write == redirected_tty_write)
1311 if (filp->f_op->write != tty_write)
1314 tty_fasync(-1, filp, 0); /* can't block */
1315 filp->f_op = &hung_up_tty_fops;
1319 /* FIXME! What are the locking issues here? This may me overdoing things..
1320 * this question is especially important now that we've removed the irqlock. */
1322 ld = tty_ldisc_ref(tty);
1323 if(ld != NULL) /* We may have no line discipline at this point */
1325 if (ld->flush_buffer)
1326 ld->flush_buffer(tty);
1327 if (tty->driver->flush_buffer)
1328 tty->driver->flush_buffer(tty);
1329 if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) &&
1331 ld->write_wakeup(tty);
1336 /* FIXME: Once we trust the LDISC code better we can wait here for
1337 ldisc completion and fix the driver call race */
1339 wake_up_interruptible(&tty->write_wait);
1340 wake_up_interruptible(&tty->read_wait);
1343 * Shutdown the current line discipline, and reset it to
1346 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1347 tty_reset_termios(tty);
1349 /* Defer ldisc switch */
1350 /* tty_deferred_ldisc_switch(N_TTY);
1352 This should get done automatically when the port closes and
1353 tty_release is called */
1355 read_lock(&tasklist_lock);
1357 do_each_pid_task(tty->session, PIDTYPE_SID, p) {
1358 spin_lock_irq(&p->sighand->siglock);
1359 if (p->signal->tty == tty)
1360 p->signal->tty = NULL;
1361 if (!p->signal->leader) {
1362 spin_unlock_irq(&p->sighand->siglock);
1365 __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
1366 __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
1367 put_pid(p->signal->tty_old_pgrp); /* A noop */
1369 p->signal->tty_old_pgrp = get_pid(tty->pgrp);
1370 spin_unlock_irq(&p->sighand->siglock);
1371 } while_each_pid_task(tty->session, PIDTYPE_SID, p);
1373 read_unlock(&tasklist_lock);
1376 put_pid(tty->session);
1378 tty->session = NULL;
1380 tty->ctrl_status = 0;
1382 * If one of the devices matches a console pointer, we
1383 * cannot just call hangup() because that will cause
1384 * tty->count and state->count to go out of sync.
1385 * So we just call close() the right number of times.
1388 if (tty->driver->close)
1389 for (n = 0; n < closecount; n++)
1390 tty->driver->close(tty, cons_filp);
1391 } else if (tty->driver->hangup)
1392 (tty->driver->hangup)(tty);
1394 /* We don't want to have driver/ldisc interactions beyond
1395 the ones we did here. The driver layer expects no
1396 calls after ->hangup() from the ldisc side. However we
1397 can't yet guarantee all that */
1399 set_bit(TTY_HUPPED, &tty->flags);
1401 tty_ldisc_enable(tty);
1402 tty_ldisc_deref(ld);
1410 * tty_hangup - trigger a hangup event
1411 * @tty: tty to hangup
1413 * A carrier loss (virtual or otherwise) has occurred on this like
1414 * schedule a hangup sequence to run after this event.
1417 void tty_hangup(struct tty_struct * tty)
1419 #ifdef TTY_DEBUG_HANGUP
1422 printk(KERN_DEBUG "%s hangup...\n", tty_name(tty, buf));
1424 schedule_work(&tty->hangup_work);
1427 EXPORT_SYMBOL(tty_hangup);
1430 * tty_vhangup - process vhangup
1431 * @tty: tty to hangup
1433 * The user has asked via system call for the terminal to be hung up.
1434 * We do this synchronously so that when the syscall returns the process
1435 * is complete. That guarantee is neccessary for security reasons.
1438 void tty_vhangup(struct tty_struct * tty)
1440 #ifdef TTY_DEBUG_HANGUP
1443 printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf));
1445 do_tty_hangup(&tty->hangup_work);
1447 EXPORT_SYMBOL(tty_vhangup);
1450 * tty_hung_up_p - was tty hung up
1451 * @filp: file pointer of tty
1453 * Return true if the tty has been subject to a vhangup or a carrier
1457 int tty_hung_up_p(struct file * filp)
1459 return (filp->f_op == &hung_up_tty_fops);
1462 EXPORT_SYMBOL(tty_hung_up_p);
1464 static void session_clear_tty(struct pid *session)
1466 struct task_struct *p;
1467 do_each_pid_task(session, PIDTYPE_SID, p) {
1469 } while_each_pid_task(session, PIDTYPE_SID, p);
1473 * disassociate_ctty - disconnect controlling tty
1474 * @on_exit: true if exiting so need to "hang up" the session
1476 * This function is typically called only by the session leader, when
1477 * it wants to disassociate itself from its controlling tty.
1479 * It performs the following functions:
1480 * (1) Sends a SIGHUP and SIGCONT to the foreground process group
1481 * (2) Clears the tty from being controlling the session
1482 * (3) Clears the controlling tty for all processes in the
1485 * The argument on_exit is set to 1 if called when a process is
1486 * exiting; it is 0 if called by the ioctl TIOCNOTTY.
1489 * BKL is taken for hysterical raisins
1490 * tty_mutex is taken to protect tty
1491 * ->siglock is taken to protect ->signal/->sighand
1492 * tasklist_lock is taken to walk process list for sessions
1493 * ->siglock is taken to protect ->signal/->sighand
1496 void disassociate_ctty(int on_exit)
1498 struct tty_struct *tty;
1499 struct pid *tty_pgrp = NULL;
1503 mutex_lock(&tty_mutex);
1504 tty = get_current_tty();
1506 tty_pgrp = get_pid(tty->pgrp);
1507 mutex_unlock(&tty_mutex);
1508 /* XXX: here we race, there is nothing protecting tty */
1509 if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)
1511 } else if (on_exit) {
1512 struct pid *old_pgrp;
1513 spin_lock_irq(¤t->sighand->siglock);
1514 old_pgrp = current->signal->tty_old_pgrp;
1515 current->signal->tty_old_pgrp = NULL;
1516 spin_unlock_irq(¤t->sighand->siglock);
1518 kill_pgrp(old_pgrp, SIGHUP, on_exit);
1519 kill_pgrp(old_pgrp, SIGCONT, on_exit);
1522 mutex_unlock(&tty_mutex);
1527 kill_pgrp(tty_pgrp, SIGHUP, on_exit);
1529 kill_pgrp(tty_pgrp, SIGCONT, on_exit);
1533 spin_lock_irq(¤t->sighand->siglock);
1534 put_pid(current->signal->tty_old_pgrp);
1535 current->signal->tty_old_pgrp = NULL;
1536 spin_unlock_irq(¤t->sighand->siglock);
1538 mutex_lock(&tty_mutex);
1539 /* It is possible that do_tty_hangup has free'd this tty */
1540 tty = get_current_tty();
1542 put_pid(tty->session);
1544 tty->session = NULL;
1547 #ifdef TTY_DEBUG_HANGUP
1548 printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
1552 mutex_unlock(&tty_mutex);
1554 /* Now clear signal->tty under the lock */
1555 read_lock(&tasklist_lock);
1556 session_clear_tty(task_session(current));
1557 read_unlock(&tasklist_lock);
1563 * stop_tty - propogate flow control
1566 * Perform flow control to the driver. For PTY/TTY pairs we
1567 * must also propogate the TIOCKPKT status. May be called
1568 * on an already stopped device and will not re-call the driver
1571 * This functionality is used by both the line disciplines for
1572 * halting incoming flow and by the driver. It may therefore be
1573 * called from any context, may be under the tty atomic_write_lock
1577 * Broken. Relies on BKL which is unsafe here.
1580 void stop_tty(struct tty_struct *tty)
1585 if (tty->link && tty->link->packet) {
1586 tty->ctrl_status &= ~TIOCPKT_START;
1587 tty->ctrl_status |= TIOCPKT_STOP;
1588 wake_up_interruptible(&tty->link->read_wait);
1590 if (tty->driver->stop)
1591 (tty->driver->stop)(tty);
1594 EXPORT_SYMBOL(stop_tty);
1597 * start_tty - propogate flow control
1598 * @tty: tty to start
1600 * Start a tty that has been stopped if at all possible. Perform
1601 * any neccessary wakeups and propogate the TIOCPKT status. If this
1602 * is the tty was previous stopped and is being started then the
1603 * driver start method is invoked and the line discipline woken.
1606 * Broken. Relies on BKL which is unsafe here.
1609 void start_tty(struct tty_struct *tty)
1611 if (!tty->stopped || tty->flow_stopped)
1614 if (tty->link && tty->link->packet) {
1615 tty->ctrl_status &= ~TIOCPKT_STOP;
1616 tty->ctrl_status |= TIOCPKT_START;
1617 wake_up_interruptible(&tty->link->read_wait);
1619 if (tty->driver->start)
1620 (tty->driver->start)(tty);
1622 /* If we have a running line discipline it may need kicking */
1626 EXPORT_SYMBOL(start_tty);
1629 * tty_read - read method for tty device files
1630 * @file: pointer to tty file
1632 * @count: size of user buffer
1635 * Perform the read system call function on this terminal device. Checks
1636 * for hung up devices before calling the line discipline method.
1639 * Locks the line discipline internally while needed
1640 * For historical reasons the line discipline read method is
1641 * invoked under the BKL. This will go away in time so do not rely on it
1642 * in new code. Multiple read calls may be outstanding in parallel.
1645 static ssize_t tty_read(struct file * file, char __user * buf, size_t count,
1649 struct tty_struct * tty;
1650 struct inode *inode;
1651 struct tty_ldisc *ld;
1653 tty = (struct tty_struct *)file->private_data;
1654 inode = file->f_path.dentry->d_inode;
1655 if (tty_paranoia_check(tty, inode, "tty_read"))
1657 if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags)))
1660 /* We want to wait for the line discipline to sort out in this
1662 ld = tty_ldisc_ref_wait(tty);
1665 i = (ld->read)(tty,file,buf,count);
1668 tty_ldisc_deref(ld);
1671 inode->i_atime = current_fs_time(inode->i_sb);
1676 * Split writes up in sane blocksizes to avoid
1677 * denial-of-service type attacks
1679 static inline ssize_t do_tty_write(
1680 ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
1681 struct tty_struct *tty,
1683 const char __user *buf,
1686 ssize_t ret = 0, written = 0;
1689 /* FIXME: O_NDELAY ... */
1690 if (mutex_lock_interruptible(&tty->atomic_write_lock)) {
1691 return -ERESTARTSYS;
1695 * We chunk up writes into a temporary buffer. This
1696 * simplifies low-level drivers immensely, since they
1697 * don't have locking issues and user mode accesses.
1699 * But if TTY_NO_WRITE_SPLIT is set, we should use a
1702 * The default chunk-size is 2kB, because the NTTY
1703 * layer has problems with bigger chunks. It will
1704 * claim to be able to handle more characters than
1707 * FIXME: This can probably go away now except that 64K chunks
1708 * are too likely to fail unless switched to vmalloc...
1711 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
1716 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
1717 if (tty->write_cnt < chunk) {
1723 buf = kmalloc(chunk, GFP_KERNEL);
1725 mutex_unlock(&tty->atomic_write_lock);
1728 kfree(tty->write_buf);
1729 tty->write_cnt = chunk;
1730 tty->write_buf = buf;
1733 /* Do the write .. */
1735 size_t size = count;
1739 if (copy_from_user(tty->write_buf, buf, size))
1742 ret = write(tty, file, tty->write_buf, size);
1752 if (signal_pending(current))
1757 struct inode *inode = file->f_path.dentry->d_inode;
1758 inode->i_mtime = current_fs_time(inode->i_sb);
1761 mutex_unlock(&tty->atomic_write_lock);
1767 * tty_write - write method for tty device file
1768 * @file: tty file pointer
1769 * @buf: user data to write
1770 * @count: bytes to write
1773 * Write data to a tty device via the line discipline.
1776 * Locks the line discipline as required
1777 * Writes to the tty driver are serialized by the atomic_write_lock
1778 * and are then processed in chunks to the device. The line discipline
1779 * write method will not be involked in parallel for each device
1780 * The line discipline write method is called under the big
1781 * kernel lock for historical reasons. New code should not rely on this.
1784 static ssize_t tty_write(struct file * file, const char __user * buf, size_t count,
1787 struct tty_struct * tty;
1788 struct inode *inode = file->f_path.dentry->d_inode;
1790 struct tty_ldisc *ld;
1792 tty = (struct tty_struct *)file->private_data;
1793 if (tty_paranoia_check(tty, inode, "tty_write"))
1795 if (!tty || !tty->driver->write || (test_bit(TTY_IO_ERROR, &tty->flags)))
1798 ld = tty_ldisc_ref_wait(tty);
1802 ret = do_tty_write(ld->write, tty, file, buf, count);
1803 tty_ldisc_deref(ld);
1807 ssize_t redirected_tty_write(struct file * file, const char __user * buf, size_t count,
1810 struct file *p = NULL;
1812 spin_lock(&redirect_lock);
1817 spin_unlock(&redirect_lock);
1821 res = vfs_write(p, buf, count, &p->f_pos);
1826 return tty_write(file, buf, count, ppos);
1829 static char ptychar[] = "pqrstuvwxyzabcde";
1832 * pty_line_name - generate name for a pty
1833 * @driver: the tty driver in use
1834 * @index: the minor number
1835 * @p: output buffer of at least 6 bytes
1837 * Generate a name from a driver reference and write it to the output
1842 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1844 int i = index + driver->name_base;
1845 /* ->name is initialized to "ttyp", but "tty" is expected */
1846 sprintf(p, "%s%c%x",
1847 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1848 ptychar[i >> 4 & 0xf], i & 0xf);
1852 * pty_line_name - generate name for a tty
1853 * @driver: the tty driver in use
1854 * @index: the minor number
1855 * @p: output buffer of at least 7 bytes
1857 * Generate a name from a driver reference and write it to the output
1862 static void tty_line_name(struct tty_driver *driver, int index, char *p)
1864 sprintf(p, "%s%d", driver->name, index + driver->name_base);
1868 * init_dev - initialise a tty device
1869 * @driver: tty driver we are opening a device on
1870 * @idx: device index
1871 * @tty: returned tty structure
1873 * Prepare a tty device. This may not be a "new" clean device but
1874 * could also be an active device. The pty drivers require special
1875 * handling because of this.
1878 * The function is called under the tty_mutex, which
1879 * protects us from the tty struct or driver itself going away.
1881 * On exit the tty device has the line discipline attached and
1882 * a reference count of 1. If a pair was created for pty/tty use
1883 * and the other was a pty master then it too has a reference count of 1.
1885 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1886 * failed open. The new code protects the open with a mutex, so it's
1887 * really quite straightforward. The mutex locking can probably be
1888 * relaxed for the (most common) case of reopening a tty.
1891 static int init_dev(struct tty_driver *driver, int idx,
1892 struct tty_struct **ret_tty)
1894 struct tty_struct *tty, *o_tty;
1895 struct ktermios *tp, **tp_loc, *o_tp, **o_tp_loc;
1896 struct ktermios *ltp, **ltp_loc, *o_ltp, **o_ltp_loc;
1899 /* check whether we're reopening an existing tty */
1900 if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
1901 tty = devpts_get_tty(idx);
1903 * If we don't have a tty here on a slave open, it's because
1904 * the master already started the close process and there's
1905 * no relation between devpts file and tty anymore.
1907 if (!tty && driver->subtype == PTY_TYPE_SLAVE) {
1912 * It's safe from now on because init_dev() is called with
1913 * tty_mutex held and release_dev() won't change tty->count
1914 * or tty->flags without having to grab tty_mutex
1916 if (tty && driver->subtype == PTY_TYPE_MASTER)
1919 tty = driver->ttys[idx];
1921 if (tty) goto fast_track;
1924 * First time open is complex, especially for PTY devices.
1925 * This code guarantees that either everything succeeds and the
1926 * TTY is ready for operation, or else the table slots are vacated
1927 * and the allocated memory released. (Except that the termios
1928 * and locked termios may be retained.)
1931 if (!try_module_get(driver->owner)) {
1940 tty = alloc_tty_struct();
1943 initialize_tty_struct(tty);
1944 tty->driver = driver;
1946 tty_line_name(driver, idx, tty->name);
1948 if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
1949 tp_loc = &tty->termios;
1950 ltp_loc = &tty->termios_locked;
1952 tp_loc = &driver->termios[idx];
1953 ltp_loc = &driver->termios_locked[idx];
1957 tp = (struct ktermios *) kmalloc(sizeof(struct ktermios),
1961 *tp = driver->init_termios;
1965 ltp = (struct ktermios *) kmalloc(sizeof(struct ktermios),
1969 memset(ltp, 0, sizeof(struct ktermios));
1972 if (driver->type == TTY_DRIVER_TYPE_PTY) {
1973 o_tty = alloc_tty_struct();
1976 initialize_tty_struct(o_tty);
1977 o_tty->driver = driver->other;
1979 tty_line_name(driver->other, idx, o_tty->name);
1981 if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
1982 o_tp_loc = &o_tty->termios;
1983 o_ltp_loc = &o_tty->termios_locked;
1985 o_tp_loc = &driver->other->termios[idx];
1986 o_ltp_loc = &driver->other->termios_locked[idx];
1990 o_tp = (struct ktermios *)
1991 kmalloc(sizeof(struct ktermios), GFP_KERNEL);
1994 *o_tp = driver->other->init_termios;
1998 o_ltp = (struct ktermios *)
1999 kmalloc(sizeof(struct ktermios), GFP_KERNEL);
2002 memset(o_ltp, 0, sizeof(struct ktermios));
2006 * Everything allocated ... set up the o_tty structure.
2008 if (!(driver->other->flags & TTY_DRIVER_DEVPTS_MEM)) {
2009 driver->other->ttys[idx] = o_tty;
2015 o_tty->termios = *o_tp_loc;
2016 o_tty->termios_locked = *o_ltp_loc;
2017 driver->other->refcount++;
2018 if (driver->subtype == PTY_TYPE_MASTER)
2021 /* Establish the links in both directions */
2027 * All structures have been allocated, so now we install them.
2028 * Failures after this point use release_tty to clean up, so
2029 * there's no need to null out the local pointers.
2031 if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
2032 driver->ttys[idx] = tty;
2039 tty->termios = *tp_loc;
2040 tty->termios_locked = *ltp_loc;
2041 /* Compatibility until drivers always set this */
2042 tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
2043 tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
2048 * Structures all installed ... call the ldisc open routines.
2049 * If we fail here just call release_tty to clean up. No need
2050 * to decrement the use counts, as release_tty doesn't care.
2053 if (tty->ldisc.open) {
2054 retval = (tty->ldisc.open)(tty);
2056 goto release_mem_out;
2058 if (o_tty && o_tty->ldisc.open) {
2059 retval = (o_tty->ldisc.open)(o_tty);
2061 if (tty->ldisc.close)
2062 (tty->ldisc.close)(tty);
2063 goto release_mem_out;
2065 tty_ldisc_enable(o_tty);
2067 tty_ldisc_enable(tty);
2071 * This fast open can be used if the tty is already open.
2072 * No memory is allocated, and the only failures are from
2073 * attempting to open a closing tty or attempting multiple
2074 * opens on a pty master.
2077 if (test_bit(TTY_CLOSING, &tty->flags)) {
2081 if (driver->type == TTY_DRIVER_TYPE_PTY &&
2082 driver->subtype == PTY_TYPE_MASTER) {
2084 * special case for PTY masters: only one open permitted,
2085 * and the slave side open count is incremented as well.
2094 tty->driver = driver; /* N.B. why do this every time?? */
2097 if(!test_bit(TTY_LDISC, &tty->flags))
2098 printk(KERN_ERR "init_dev but no ldisc\n");
2102 /* All paths come through here to release the mutex */
2106 /* Release locally allocated memory ... nothing placed in slots */
2110 free_tty_struct(o_tty);
2113 free_tty_struct(tty);
2116 module_put(driver->owner);
2120 /* call the tty release_tty routine to clean out this slot */
2122 if (printk_ratelimit())
2123 printk(KERN_INFO "init_dev: ldisc open failed, "
2124 "clearing slot %d\n", idx);
2125 release_tty(tty, idx);
2130 * release_one_tty - release tty structure memory
2132 * Releases memory associated with a tty structure, and clears out the
2133 * driver table slots. This function is called when a device is no longer
2134 * in use. It also gets called when setup of a device fails.
2137 * tty_mutex - sometimes only
2138 * takes the file list lock internally when working on the list
2139 * of ttys that the driver keeps.
2140 * FIXME: should we require tty_mutex is held here ??
2142 static void release_one_tty(struct tty_struct *tty, int idx)
2144 int devpts = tty->driver->flags & TTY_DRIVER_DEVPTS_MEM;
2145 struct ktermios *tp;
2148 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;
2164 tty->driver->refcount--;
2167 list_del_init(&tty->tty_files);
2170 free_tty_struct(tty);
2174 * release_tty - release tty structure memory
2176 * Release both @tty and a possible linked partner (think pty pair),
2177 * and decrement the refcount of the backing module.
2180 * tty_mutex - sometimes only
2181 * takes the file list lock internally when working on the list
2182 * of ttys that the driver keeps.
2183 * FIXME: should we require tty_mutex is held here ??
2185 static void release_tty(struct tty_struct *tty, int idx)
2187 struct tty_driver *driver = tty->driver;
2190 release_one_tty(tty->link, idx);
2191 release_one_tty(tty, idx);
2192 module_put(driver->owner);
2196 * Even releasing the tty structures is a tricky business.. We have
2197 * to be very careful that the structures are all released at the
2198 * same time, as interrupts might otherwise get the wrong pointers.
2200 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
2201 * lead to double frees or releasing memory still in use.
2203 static void release_dev(struct file * filp)
2205 struct tty_struct *tty, *o_tty;
2206 int pty_master, tty_closing, o_tty_closing, do_sleep;
2210 unsigned long flags;
2212 tty = (struct tty_struct *)filp->private_data;
2213 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "release_dev"))
2216 check_tty_count(tty, "release_dev");
2218 tty_fasync(-1, filp, 0);
2221 pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2222 tty->driver->subtype == PTY_TYPE_MASTER);
2223 devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0;
2226 #ifdef TTY_PARANOIA_CHECK
2227 if (idx < 0 || idx >= tty->driver->num) {
2228 printk(KERN_DEBUG "release_dev: bad idx when trying to "
2229 "free (%s)\n", tty->name);
2232 if (!(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
2233 if (tty != tty->driver->ttys[idx]) {
2234 printk(KERN_DEBUG "release_dev: driver.table[%d] not tty "
2235 "for (%s)\n", idx, tty->name);
2238 if (tty->termios != tty->driver->termios[idx]) {
2239 printk(KERN_DEBUG "release_dev: driver.termios[%d] not termios "
2244 if (tty->termios_locked != tty->driver->termios_locked[idx]) {
2245 printk(KERN_DEBUG "release_dev: driver.termios_locked[%d] not "
2246 "termios_locked for (%s)\n",
2253 #ifdef TTY_DEBUG_HANGUP
2254 printk(KERN_DEBUG "release_dev of %s (tty count=%d)...",
2255 tty_name(tty, buf), tty->count);
2258 #ifdef TTY_PARANOIA_CHECK
2259 if (tty->driver->other &&
2260 !(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
2261 if (o_tty != tty->driver->other->ttys[idx]) {
2262 printk(KERN_DEBUG "release_dev: other->table[%d] "
2263 "not o_tty for (%s)\n",
2267 if (o_tty->termios != tty->driver->other->termios[idx]) {
2268 printk(KERN_DEBUG "release_dev: other->termios[%d] "
2269 "not o_termios for (%s)\n",
2273 if (o_tty->termios_locked !=
2274 tty->driver->other->termios_locked[idx]) {
2275 printk(KERN_DEBUG "release_dev: other->termios_locked["
2276 "%d] not o_termios_locked for (%s)\n",
2280 if (o_tty->link != tty) {
2281 printk(KERN_DEBUG "release_dev: bad pty pointers\n");
2286 if (tty->driver->close)
2287 tty->driver->close(tty, filp);
2290 * Sanity check: if tty->count is going to zero, there shouldn't be
2291 * any waiters on tty->read_wait or tty->write_wait. We test the
2292 * wait queues and kick everyone out _before_ actually starting to
2293 * close. This ensures that we won't block while releasing the tty
2296 * The test for the o_tty closing is necessary, since the master and
2297 * slave sides may close in any order. If the slave side closes out
2298 * first, its count will be one, since the master side holds an open.
2299 * Thus this test wouldn't be triggered at the time the slave closes,
2302 * Note that it's possible for the tty to be opened again while we're
2303 * flushing out waiters. By recalculating the closing flags before
2304 * each iteration we avoid any problems.
2307 /* Guard against races with tty->count changes elsewhere and
2308 opens on /dev/tty */
2310 mutex_lock(&tty_mutex);
2311 tty_closing = tty->count <= 1;
2312 o_tty_closing = o_tty &&
2313 (o_tty->count <= (pty_master ? 1 : 0));
2317 if (waitqueue_active(&tty->read_wait)) {
2318 wake_up(&tty->read_wait);
2321 if (waitqueue_active(&tty->write_wait)) {
2322 wake_up(&tty->write_wait);
2326 if (o_tty_closing) {
2327 if (waitqueue_active(&o_tty->read_wait)) {
2328 wake_up(&o_tty->read_wait);
2331 if (waitqueue_active(&o_tty->write_wait)) {
2332 wake_up(&o_tty->write_wait);
2339 printk(KERN_WARNING "release_dev: %s: read/write wait queue "
2340 "active!\n", tty_name(tty, buf));
2341 mutex_unlock(&tty_mutex);
2346 * The closing flags are now consistent with the open counts on
2347 * both sides, and we've completed the last operation that could
2348 * block, so it's safe to proceed with closing.
2351 if (--o_tty->count < 0) {
2352 printk(KERN_WARNING "release_dev: bad pty slave count "
2354 o_tty->count, tty_name(o_tty, buf));
2358 if (--tty->count < 0) {
2359 printk(KERN_WARNING "release_dev: bad tty->count (%d) for %s\n",
2360 tty->count, tty_name(tty, buf));
2365 * We've decremented tty->count, so we need to remove this file
2366 * descriptor off the tty->tty_files list; this serves two
2368 * - check_tty_count sees the correct number of file descriptors
2369 * associated with this tty.
2370 * - do_tty_hangup no longer sees this file descriptor as
2371 * something that needs to be handled for hangups.
2374 filp->private_data = NULL;
2377 * Perform some housekeeping before deciding whether to return.
2379 * Set the TTY_CLOSING flag if this was the last open. In the
2380 * case of a pty we may have to wait around for the other side
2381 * to close, and TTY_CLOSING makes sure we can't be reopened.
2384 set_bit(TTY_CLOSING, &tty->flags);
2386 set_bit(TTY_CLOSING, &o_tty->flags);
2389 * If _either_ side is closing, make sure there aren't any
2390 * processes that still think tty or o_tty is their controlling
2393 if (tty_closing || o_tty_closing) {
2394 read_lock(&tasklist_lock);
2395 session_clear_tty(tty->session);
2397 session_clear_tty(o_tty->session);
2398 read_unlock(&tasklist_lock);
2401 mutex_unlock(&tty_mutex);
2403 /* check whether both sides are closing ... */
2404 if (!tty_closing || (o_tty && !o_tty_closing))
2407 #ifdef TTY_DEBUG_HANGUP
2408 printk(KERN_DEBUG "freeing tty structure...");
2411 * Prevent flush_to_ldisc() from rescheduling the work for later. Then
2412 * kill any delayed work. As this is the final close it does not
2413 * race with the set_ldisc code path.
2415 clear_bit(TTY_LDISC, &tty->flags);
2416 cancel_delayed_work(&tty->buf.work);
2419 * Wait for ->hangup_work and ->buf.work handlers to terminate
2422 flush_scheduled_work();
2425 * Wait for any short term users (we know they are just driver
2426 * side waiters as the file is closing so user count on the file
2429 spin_lock_irqsave(&tty_ldisc_lock, flags);
2430 while(tty->ldisc.refcount)
2432 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
2433 wait_event(tty_ldisc_wait, tty->ldisc.refcount == 0);
2434 spin_lock_irqsave(&tty_ldisc_lock, flags);
2436 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
2438 * Shutdown the current line discipline, and reset it to N_TTY.
2439 * N.B. why reset ldisc when we're releasing the memory??
2441 * FIXME: this MUST get fixed for the new reflocking
2443 if (tty->ldisc.close)
2444 (tty->ldisc.close)(tty);
2445 tty_ldisc_put(tty->ldisc.num);
2448 * Switch the line discipline back
2450 tty_ldisc_assign(tty, tty_ldisc_get(N_TTY));
2451 tty_set_termios_ldisc(tty,N_TTY);
2453 /* FIXME: could o_tty be in setldisc here ? */
2454 clear_bit(TTY_LDISC, &o_tty->flags);
2455 if (o_tty->ldisc.close)
2456 (o_tty->ldisc.close)(o_tty);
2457 tty_ldisc_put(o_tty->ldisc.num);
2458 tty_ldisc_assign(o_tty, tty_ldisc_get(N_TTY));
2459 tty_set_termios_ldisc(o_tty,N_TTY);
2462 * The release_tty function takes care of the details of clearing
2463 * the slots and preserving the termios structure.
2465 release_tty(tty, idx);
2467 #ifdef CONFIG_UNIX98_PTYS
2468 /* Make this pty number available for reallocation */
2470 down(&allocated_ptys_lock);
2471 idr_remove(&allocated_ptys, idx);
2472 up(&allocated_ptys_lock);
2479 * tty_open - open a tty device
2480 * @inode: inode of device file
2481 * @filp: file pointer to tty
2483 * tty_open and tty_release keep up the tty count that contains the
2484 * number of opens done on a tty. We cannot use the inode-count, as
2485 * different inodes might point to the same tty.
2487 * Open-counting is needed for pty masters, as well as for keeping
2488 * track of serial lines: DTR is dropped when the last close happens.
2489 * (This is not done solely through tty->count, now. - Ted 1/27/92)
2491 * The termios state of a pty is reset on first open so that
2492 * settings don't persist across reuse.
2494 * Locking: tty_mutex protects tty, get_tty_driver and init_dev work.
2495 * tty->count should protect the rest.
2496 * ->siglock protects ->signal/->sighand
2499 static int tty_open(struct inode * inode, struct file * filp)
2501 struct tty_struct *tty;
2503 struct tty_driver *driver;
2505 dev_t device = inode->i_rdev;
2506 unsigned short saved_flags = filp->f_flags;
2508 nonseekable_open(inode, filp);
2511 noctty = filp->f_flags & O_NOCTTY;
2515 mutex_lock(&tty_mutex);
2517 if (device == MKDEV(TTYAUX_MAJOR,0)) {
2518 tty = get_current_tty();
2520 mutex_unlock(&tty_mutex);
2523 driver = tty->driver;
2525 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
2530 if (device == MKDEV(TTY_MAJOR,0)) {
2531 extern struct tty_driver *console_driver;
2532 driver = console_driver;
2538 if (device == MKDEV(TTYAUX_MAJOR,1)) {
2539 driver = console_device(&index);
2541 /* Don't let /dev/console block */
2542 filp->f_flags |= O_NONBLOCK;
2546 mutex_unlock(&tty_mutex);
2550 driver = get_tty_driver(device, &index);
2552 mutex_unlock(&tty_mutex);
2556 retval = init_dev(driver, index, &tty);
2557 mutex_unlock(&tty_mutex);
2561 filp->private_data = tty;
2562 file_move(filp, &tty->tty_files);
2563 check_tty_count(tty, "tty_open");
2564 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2565 tty->driver->subtype == PTY_TYPE_MASTER)
2567 #ifdef TTY_DEBUG_HANGUP
2568 printk(KERN_DEBUG "opening %s...", tty->name);
2571 if (tty->driver->open)
2572 retval = tty->driver->open(tty, filp);
2576 filp->f_flags = saved_flags;
2578 if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
2582 #ifdef TTY_DEBUG_HANGUP
2583 printk(KERN_DEBUG "error %d in opening %s...", retval,
2587 if (retval != -ERESTARTSYS)
2589 if (signal_pending(current))
2593 * Need to reset f_op in case a hangup happened.
2595 if (filp->f_op == &hung_up_tty_fops)
2596 filp->f_op = &tty_fops;
2600 mutex_lock(&tty_mutex);
2601 spin_lock_irq(¤t->sighand->siglock);
2603 current->signal->leader &&
2604 !current->signal->tty &&
2605 tty->session == NULL)
2606 __proc_set_tty(current, tty);
2607 spin_unlock_irq(¤t->sighand->siglock);
2608 mutex_unlock(&tty_mutex);
2612 #ifdef CONFIG_UNIX98_PTYS
2614 * ptmx_open - open a unix 98 pty master
2615 * @inode: inode of device file
2616 * @filp: file pointer to tty
2618 * Allocate a unix98 pty master device from the ptmx driver.
2620 * Locking: tty_mutex protects theinit_dev work. tty->count should
2622 * allocated_ptys_lock handles the list of free pty numbers
2625 static int ptmx_open(struct inode * inode, struct file * filp)
2627 struct tty_struct *tty;
2632 nonseekable_open(inode, filp);
2634 /* find a device that is not in use. */
2635 down(&allocated_ptys_lock);
2636 if (!idr_pre_get(&allocated_ptys, GFP_KERNEL)) {
2637 up(&allocated_ptys_lock);
2640 idr_ret = idr_get_new(&allocated_ptys, NULL, &index);
2642 up(&allocated_ptys_lock);
2643 if (idr_ret == -EAGAIN)
2647 if (index >= pty_limit) {
2648 idr_remove(&allocated_ptys, index);
2649 up(&allocated_ptys_lock);
2652 up(&allocated_ptys_lock);
2654 mutex_lock(&tty_mutex);
2655 retval = init_dev(ptm_driver, index, &tty);
2656 mutex_unlock(&tty_mutex);
2661 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
2662 filp->private_data = tty;
2663 file_move(filp, &tty->tty_files);
2666 if (devpts_pty_new(tty->link))
2669 check_tty_count(tty, "tty_open");
2670 retval = ptm_driver->open(tty, filp);
2677 down(&allocated_ptys_lock);
2678 idr_remove(&allocated_ptys, index);
2679 up(&allocated_ptys_lock);
2685 * tty_release - vfs callback for close
2686 * @inode: inode of tty
2687 * @filp: file pointer for handle to tty
2689 * Called the last time each file handle is closed that references
2690 * this tty. There may however be several such references.
2693 * Takes bkl. See release_dev
2696 static int tty_release(struct inode * inode, struct file * filp)
2705 * tty_poll - check tty status
2706 * @filp: file being polled
2707 * @wait: poll wait structures to update
2709 * Call the line discipline polling method to obtain the poll
2710 * status of the device.
2712 * Locking: locks called line discipline but ldisc poll method
2713 * may be re-entered freely by other callers.
2716 static unsigned int tty_poll(struct file * filp, poll_table * wait)
2718 struct tty_struct * tty;
2719 struct tty_ldisc *ld;
2722 tty = (struct tty_struct *)filp->private_data;
2723 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_poll"))
2726 ld = tty_ldisc_ref_wait(tty);
2728 ret = (ld->poll)(tty, filp, wait);
2729 tty_ldisc_deref(ld);
2733 static int tty_fasync(int fd, struct file * filp, int on)
2735 struct tty_struct * tty;
2738 tty = (struct tty_struct *)filp->private_data;
2739 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_fasync"))
2742 retval = fasync_helper(fd, filp, on, &tty->fasync);
2749 if (!waitqueue_active(&tty->read_wait))
2750 tty->minimum_to_wake = 1;
2753 type = PIDTYPE_PGID;
2755 pid = task_pid(current);
2758 retval = __f_setown(filp, pid, type, 0);
2762 if (!tty->fasync && !waitqueue_active(&tty->read_wait))
2763 tty->minimum_to_wake = N_TTY_BUF_SIZE;
2769 * tiocsti - fake input character
2770 * @tty: tty to fake input into
2771 * @p: pointer to character
2773 * Fake input to a tty device. Does the neccessary locking and
2776 * FIXME: does not honour flow control ??
2779 * Called functions take tty_ldisc_lock
2780 * current->signal->tty check is safe without locks
2782 * FIXME: may race normal receive processing
2785 static int tiocsti(struct tty_struct *tty, char __user *p)
2788 struct tty_ldisc *ld;
2790 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2792 if (get_user(ch, p))
2794 ld = tty_ldisc_ref_wait(tty);
2795 ld->receive_buf(tty, &ch, &mbz, 1);
2796 tty_ldisc_deref(ld);
2801 * tiocgwinsz - implement window query ioctl
2803 * @arg: user buffer for result
2805 * Copies the kernel idea of the window size into the user buffer.
2807 * Locking: tty->termios_mutex is taken to ensure the winsize data
2811 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user * arg)
2815 mutex_lock(&tty->termios_mutex);
2816 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2817 mutex_unlock(&tty->termios_mutex);
2819 return err ? -EFAULT: 0;
2823 * tiocswinsz - implement window size set ioctl
2825 * @arg: user buffer for result
2827 * Copies the user idea of the window size to the kernel. Traditionally
2828 * this is just advisory information but for the Linux console it
2829 * actually has driver level meaning and triggers a VC resize.
2832 * Called function use the console_sem is used to ensure we do
2833 * not try and resize the console twice at once.
2834 * The tty->termios_mutex is used to ensure we don't double
2835 * resize and get confused. Lock order - tty->termios_mutex before
2839 static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty,
2840 struct winsize __user * arg)
2842 struct winsize tmp_ws;
2844 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2847 mutex_lock(&tty->termios_mutex);
2848 if (!memcmp(&tmp_ws, &tty->winsize, sizeof(*arg)))
2852 if (tty->driver->type == TTY_DRIVER_TYPE_CONSOLE) {
2853 if (vc_lock_resize(tty->driver_data, tmp_ws.ws_col,
2855 mutex_unlock(&tty->termios_mutex);
2861 kill_pgrp(tty->pgrp, SIGWINCH, 1);
2862 if ((real_tty->pgrp != tty->pgrp) && real_tty->pgrp)
2863 kill_pgrp(real_tty->pgrp, SIGWINCH, 1);
2864 tty->winsize = tmp_ws;
2865 real_tty->winsize = tmp_ws;
2867 mutex_unlock(&tty->termios_mutex);
2872 * tioccons - allow admin to move logical console
2873 * @file: the file to become console
2875 * Allow the adminstrator to move the redirected console device
2877 * Locking: uses redirect_lock to guard the redirect information
2880 static int tioccons(struct file *file)
2882 if (!capable(CAP_SYS_ADMIN))
2884 if (file->f_op->write == redirected_tty_write) {
2886 spin_lock(&redirect_lock);
2889 spin_unlock(&redirect_lock);
2894 spin_lock(&redirect_lock);
2896 spin_unlock(&redirect_lock);
2901 spin_unlock(&redirect_lock);
2906 * fionbio - non blocking ioctl
2907 * @file: file to set blocking value
2908 * @p: user parameter
2910 * Historical tty interfaces had a blocking control ioctl before
2911 * the generic functionality existed. This piece of history is preserved
2912 * in the expected tty API of posix OS's.
2914 * Locking: none, the open fle handle ensures it won't go away.
2917 static int fionbio(struct file *file, int __user *p)
2921 if (get_user(nonblock, p))
2925 file->f_flags |= O_NONBLOCK;
2927 file->f_flags &= ~O_NONBLOCK;
2932 * tiocsctty - set controlling tty
2933 * @tty: tty structure
2934 * @arg: user argument
2936 * This ioctl is used to manage job control. It permits a session
2937 * leader to set this tty as the controlling tty for the session.
2940 * Takes tty_mutex() to protect tty instance
2941 * Takes tasklist_lock internally to walk sessions
2942 * Takes ->siglock() when updating signal->tty
2945 static int tiocsctty(struct tty_struct *tty, int arg)
2948 if (current->signal->leader && (task_session(current) == tty->session))
2951 mutex_lock(&tty_mutex);
2953 * The process must be a session leader and
2954 * not have a controlling tty already.
2956 if (!current->signal->leader || current->signal->tty) {
2963 * This tty is already the controlling
2964 * tty for another session group!
2966 if ((arg == 1) && capable(CAP_SYS_ADMIN)) {
2970 read_lock(&tasklist_lock);
2971 session_clear_tty(tty->session);
2972 read_unlock(&tasklist_lock);
2978 proc_set_tty(current, tty);
2980 mutex_unlock(&tty_mutex);
2985 * tiocgpgrp - get process group
2986 * @tty: tty passed by user
2987 * @real_tty: tty side of the tty pased by the user if a pty else the tty
2990 * Obtain the process group of the tty. If there is no process group
2993 * Locking: none. Reference to current->signal->tty is safe.
2996 static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
2999 * (tty == real_tty) is a cheap way of
3000 * testing if the tty is NOT a master pty.
3002 if (tty == real_tty && current->signal->tty != real_tty)
3004 return put_user(pid_nr(real_tty->pgrp), p);
3008 * tiocspgrp - attempt to set process group
3009 * @tty: tty passed by user
3010 * @real_tty: tty side device matching tty passed by user
3013 * Set the process group of the tty to the session passed. Only
3014 * permitted where the tty session is our session.
3019 static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
3023 int retval = tty_check_change(real_tty);
3029 if (!current->signal->tty ||
3030 (current->signal->tty != real_tty) ||
3031 (real_tty->session != task_session(current)))
3033 if (get_user(pgrp_nr, p))
3038 pgrp = find_pid(pgrp_nr);
3043 if (session_of_pgrp(pgrp) != task_session(current))
3046 put_pid(real_tty->pgrp);
3047 real_tty->pgrp = get_pid(pgrp);
3054 * tiocgsid - get session id
3055 * @tty: tty passed by user
3056 * @real_tty: tty side of the tty pased by the user if a pty else the tty
3057 * @p: pointer to returned session id
3059 * Obtain the session id of the tty. If there is no session
3062 * Locking: none. Reference to current->signal->tty is safe.
3065 static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
3068 * (tty == real_tty) is a cheap way of
3069 * testing if the tty is NOT a master pty.
3071 if (tty == real_tty && current->signal->tty != real_tty)
3073 if (!real_tty->session)
3075 return put_user(pid_nr(real_tty->session), p);
3079 * tiocsetd - set line discipline
3081 * @p: pointer to user data
3083 * Set the line discipline according to user request.
3085 * Locking: see tty_set_ldisc, this function is just a helper
3088 static int tiocsetd(struct tty_struct *tty, int __user *p)
3092 if (get_user(ldisc, p))
3094 return tty_set_ldisc(tty, ldisc);
3098 * send_break - performed time break
3099 * @tty: device to break on
3100 * @duration: timeout in mS
3102 * Perform a timed break on hardware that lacks its own driver level
3103 * timed break functionality.
3106 * atomic_write_lock serializes
3110 static int send_break(struct tty_struct *tty, unsigned int duration)
3112 if (mutex_lock_interruptible(&tty->atomic_write_lock))
3114 tty->driver->break_ctl(tty, -1);
3115 if (!signal_pending(current)) {
3116 msleep_interruptible(duration);
3118 tty->driver->break_ctl(tty, 0);
3119 mutex_unlock(&tty->atomic_write_lock);
3120 if (signal_pending(current))
3126 * tiocmget - get modem status
3128 * @file: user file pointer
3129 * @p: pointer to result
3131 * Obtain the modem status bits from the tty driver if the feature
3132 * is supported. Return -EINVAL if it is not available.
3134 * Locking: none (up to the driver)
3137 static int tty_tiocmget(struct tty_struct *tty, struct file *file, int __user *p)
3139 int retval = -EINVAL;
3141 if (tty->driver->tiocmget) {
3142 retval = tty->driver->tiocmget(tty, file);
3145 retval = put_user(retval, p);
3151 * tiocmset - set modem status
3153 * @file: user file pointer
3154 * @cmd: command - clear bits, set bits or set all
3155 * @p: pointer to desired bits
3157 * Set the modem status bits from the tty driver if the feature
3158 * is supported. Return -EINVAL if it is not available.
3160 * Locking: none (up to the driver)
3163 static int tty_tiocmset(struct tty_struct *tty, struct file *file, unsigned int cmd,
3166 int retval = -EINVAL;
3168 if (tty->driver->tiocmset) {
3169 unsigned int set, clear, val;
3171 retval = get_user(val, p);
3189 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
3190 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
3192 retval = tty->driver->tiocmset(tty, file, set, clear);
3198 * Split this up, as gcc can choke on it otherwise..
3200 int tty_ioctl(struct inode * inode, struct file * file,
3201 unsigned int cmd, unsigned long arg)
3203 struct tty_struct *tty, *real_tty;
3204 void __user *p = (void __user *)arg;
3206 struct tty_ldisc *ld;
3208 tty = (struct tty_struct *)file->private_data;
3209 if (tty_paranoia_check(tty, inode, "tty_ioctl"))
3212 /* CHECKME: is this safe as one end closes ? */
3215 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
3216 tty->driver->subtype == PTY_TYPE_MASTER)
3217 real_tty = tty->link;
3220 * Break handling by driver
3222 if (!tty->driver->break_ctl) {
3226 if (tty->driver->ioctl)
3227 return tty->driver->ioctl(tty, file, cmd, arg);
3230 /* These two ioctl's always return success; even if */
3231 /* the driver doesn't support them. */
3234 if (!tty->driver->ioctl)
3236 retval = tty->driver->ioctl(tty, file, cmd, arg);
3237 if (retval == -ENOIOCTLCMD)
3244 * Factor out some common prep work
3252 retval = tty_check_change(tty);
3255 if (cmd != TIOCCBRK) {
3256 tty_wait_until_sent(tty, 0);
3257 if (signal_pending(current))
3265 return tiocsti(tty, p);
3267 return tiocgwinsz(tty, p);
3269 return tiocswinsz(tty, real_tty, p);
3271 return real_tty!=tty ? -EINVAL : tioccons(file);
3273 return fionbio(file, p);
3275 set_bit(TTY_EXCLUSIVE, &tty->flags);
3278 clear_bit(TTY_EXCLUSIVE, &tty->flags);
3281 if (current->signal->tty != tty)
3283 if (current->signal->leader)
3284 disassociate_ctty(0);
3285 proc_clear_tty(current);
3288 return tiocsctty(tty, arg);
3290 return tiocgpgrp(tty, real_tty, p);
3292 return tiocspgrp(tty, real_tty, p);
3294 return tiocgsid(tty, real_tty, p);
3296 /* FIXME: check this is ok */
3297 return put_user(tty->ldisc.num, (int __user *)p);
3299 return tiocsetd(tty, p);
3302 return tioclinux(tty, arg);
3307 case TIOCSBRK: /* Turn break on, unconditionally */
3308 tty->driver->break_ctl(tty, -1);
3311 case TIOCCBRK: /* Turn break off, unconditionally */
3312 tty->driver->break_ctl(tty, 0);
3314 case TCSBRK: /* SVID version: non-zero arg --> no break */
3315 /* non-zero arg means wait for all output data
3316 * to be sent (performed above) but don't send break.
3317 * This is used by the tcdrain() termios function.
3320 return send_break(tty, 250);
3322 case TCSBRKP: /* support for POSIX tcsendbreak() */
3323 return send_break(tty, arg ? arg*100 : 250);
3326 return tty_tiocmget(tty, file, p);
3331 return tty_tiocmset(tty, file, cmd, p);
3333 if (tty->driver->ioctl) {
3334 retval = (tty->driver->ioctl)(tty, file, cmd, arg);
3335 if (retval != -ENOIOCTLCMD)
3338 ld = tty_ldisc_ref_wait(tty);
3341 retval = ld->ioctl(tty, file, cmd, arg);
3342 if (retval == -ENOIOCTLCMD)
3345 tty_ldisc_deref(ld);
3351 * This implements the "Secure Attention Key" --- the idea is to
3352 * prevent trojan horses by killing all processes associated with this
3353 * tty when the user hits the "Secure Attention Key". Required for
3354 * super-paranoid applications --- see the Orange Book for more details.
3356 * This code could be nicer; ideally it should send a HUP, wait a few
3357 * seconds, then send a INT, and then a KILL signal. But you then
3358 * have to coordinate with the init process, since all processes associated
3359 * with the current tty must be dead before the new getty is allowed
3362 * Now, if it would be correct ;-/ The current code has a nasty hole -
3363 * it doesn't catch files in flight. We may send the descriptor to ourselves
3364 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
3366 * Nasty bug: do_SAK is being called in interrupt context. This can
3367 * deadlock. We punt it up to process context. AKPM - 16Mar2001
3369 void __do_SAK(struct tty_struct *tty)
3374 struct task_struct *g, *p;
3375 struct pid *session;
3378 struct fdtable *fdt;
3382 session = tty->session;
3384 tty_ldisc_flush(tty);
3386 if (tty->driver->flush_buffer)
3387 tty->driver->flush_buffer(tty);
3389 read_lock(&tasklist_lock);
3390 /* Kill the entire session */
3391 do_each_pid_task(session, PIDTYPE_SID, p) {
3392 printk(KERN_NOTICE "SAK: killed process %d"
3393 " (%s): process_session(p)==tty->session\n",
3395 send_sig(SIGKILL, p, 1);
3396 } while_each_pid_task(session, PIDTYPE_SID, p);
3397 /* Now kill any processes that happen to have the
3400 do_each_thread(g, p) {
3401 if (p->signal->tty == tty) {
3402 printk(KERN_NOTICE "SAK: killed process %d"
3403 " (%s): process_session(p)==tty->session\n",
3405 send_sig(SIGKILL, p, 1);
3411 * We don't take a ref to the file, so we must
3412 * hold ->file_lock instead.
3414 spin_lock(&p->files->file_lock);
3415 fdt = files_fdtable(p->files);
3416 for (i=0; i < fdt->max_fds; i++) {
3417 filp = fcheck_files(p->files, i);
3420 if (filp->f_op->read == tty_read &&
3421 filp->private_data == tty) {
3422 printk(KERN_NOTICE "SAK: killed process %d"
3423 " (%s): fd#%d opened to the tty\n",
3424 p->pid, p->comm, i);
3425 force_sig(SIGKILL, p);
3429 spin_unlock(&p->files->file_lock);
3432 } while_each_thread(g, p);
3433 read_unlock(&tasklist_lock);
3437 static void do_SAK_work(struct work_struct *work)
3439 struct tty_struct *tty =
3440 container_of(work, struct tty_struct, SAK_work);
3445 * The tq handling here is a little racy - tty->SAK_work may already be queued.
3446 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
3447 * the values which we write to it will be identical to the values which it
3448 * already has. --akpm
3450 void do_SAK(struct tty_struct *tty)
3454 schedule_work(&tty->SAK_work);
3457 EXPORT_SYMBOL(do_SAK);
3461 * @work: tty structure passed from work queue.
3463 * This routine is called out of the software interrupt to flush data
3464 * from the buffer chain to the line discipline.
3466 * Locking: holds tty->buf.lock to guard buffer list. Drops the lock
3467 * while invoking the line discipline receive_buf method. The
3468 * receive_buf method is single threaded for each tty instance.
3471 static void flush_to_ldisc(struct work_struct *work)
3473 struct tty_struct *tty =
3474 container_of(work, struct tty_struct, buf.work.work);
3475 unsigned long flags;
3476 struct tty_ldisc *disc;
3477 struct tty_buffer *tbuf, *head;
3479 unsigned char *flag_buf;
3481 disc = tty_ldisc_ref(tty);
3482 if (disc == NULL) /* !TTY_LDISC */
3485 spin_lock_irqsave(&tty->buf.lock, flags);
3486 head = tty->buf.head;
3488 tty->buf.head = NULL;
3490 int count = head->commit - head->read;
3492 if (head->next == NULL)
3496 tty_buffer_free(tty, tbuf);
3499 if (!tty->receive_room) {
3500 schedule_delayed_work(&tty->buf.work, 1);
3503 if (count > tty->receive_room)
3504 count = tty->receive_room;
3505 char_buf = head->char_buf_ptr + head->read;
3506 flag_buf = head->flag_buf_ptr + head->read;
3507 head->read += count;
3508 spin_unlock_irqrestore(&tty->buf.lock, flags);
3509 disc->receive_buf(tty, char_buf, flag_buf, count);
3510 spin_lock_irqsave(&tty->buf.lock, flags);
3512 tty->buf.head = head;
3514 spin_unlock_irqrestore(&tty->buf.lock, flags);
3516 tty_ldisc_deref(disc);
3520 * tty_flip_buffer_push - terminal
3523 * Queue a push of the terminal flip buffers to the line discipline. This
3524 * function must not be called from IRQ context if tty->low_latency is set.
3526 * In the event of the queue being busy for flipping the work will be
3527 * held off and retried later.
3529 * Locking: tty buffer lock. Driver locks in low latency mode.
3532 void tty_flip_buffer_push(struct tty_struct *tty)
3534 unsigned long flags;
3535 spin_lock_irqsave(&tty->buf.lock, flags);
3536 if (tty->buf.tail != NULL)
3537 tty->buf.tail->commit = tty->buf.tail->used;
3538 spin_unlock_irqrestore(&tty->buf.lock, flags);
3540 if (tty->low_latency)
3541 flush_to_ldisc(&tty->buf.work.work);
3543 schedule_delayed_work(&tty->buf.work, 1);
3546 EXPORT_SYMBOL(tty_flip_buffer_push);
3550 * initialize_tty_struct
3551 * @tty: tty to initialize
3553 * This subroutine initializes a tty structure that has been newly
3556 * Locking: none - tty in question must not be exposed at this point
3559 static void initialize_tty_struct(struct tty_struct *tty)
3561 memset(tty, 0, sizeof(struct tty_struct));
3562 tty->magic = TTY_MAGIC;
3563 tty_ldisc_assign(tty, tty_ldisc_get(N_TTY));
3564 tty->session = NULL;
3566 tty->overrun_time = jiffies;
3567 tty->buf.head = tty->buf.tail = NULL;
3568 tty_buffer_init(tty);
3569 INIT_DELAYED_WORK(&tty->buf.work, flush_to_ldisc);
3570 init_MUTEX(&tty->buf.pty_sem);
3571 mutex_init(&tty->termios_mutex);
3572 init_waitqueue_head(&tty->write_wait);
3573 init_waitqueue_head(&tty->read_wait);
3574 INIT_WORK(&tty->hangup_work, do_tty_hangup);
3575 mutex_init(&tty->atomic_read_lock);
3576 mutex_init(&tty->atomic_write_lock);
3577 spin_lock_init(&tty->read_lock);
3578 INIT_LIST_HEAD(&tty->tty_files);
3579 INIT_WORK(&tty->SAK_work, do_SAK_work);
3583 * The default put_char routine if the driver did not define one.
3586 static void tty_default_put_char(struct tty_struct *tty, unsigned char ch)
3588 tty->driver->write(tty, &ch, 1);
3591 static struct class *tty_class;
3594 * tty_register_device - register a tty device
3595 * @driver: the tty driver that describes the tty device
3596 * @index: the index in the tty driver for this tty device
3597 * @device: a struct device that is associated with this tty device.
3598 * This field is optional, if there is no known struct device
3599 * for this tty device it can be set to NULL safely.
3601 * Returns a pointer to the struct device for this tty device
3602 * (or ERR_PTR(-EFOO) on error).
3604 * This call is required to be made to register an individual tty device
3605 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3606 * that bit is not set, this function should not be called by a tty
3612 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
3613 struct device *device)
3616 dev_t dev = MKDEV(driver->major, driver->minor_start) + index;
3618 if (index >= driver->num) {
3619 printk(KERN_ERR "Attempt to register invalid tty line number "
3621 return ERR_PTR(-EINVAL);
3624 if (driver->type == TTY_DRIVER_TYPE_PTY)
3625 pty_line_name(driver, index, name);
3627 tty_line_name(driver, index, name);
3629 return device_create(tty_class, device, dev, name);
3633 * tty_unregister_device - unregister a tty device
3634 * @driver: the tty driver that describes the tty device
3635 * @index: the index in the tty driver for this tty device
3637 * If a tty device is registered with a call to tty_register_device() then
3638 * this function must be called when the tty device is gone.
3643 void tty_unregister_device(struct tty_driver *driver, unsigned index)
3645 device_destroy(tty_class, MKDEV(driver->major, driver->minor_start) + index);
3648 EXPORT_SYMBOL(tty_register_device);
3649 EXPORT_SYMBOL(tty_unregister_device);
3651 struct tty_driver *alloc_tty_driver(int lines)
3653 struct tty_driver *driver;
3655 driver = kmalloc(sizeof(struct tty_driver), GFP_KERNEL);
3657 memset(driver, 0, sizeof(struct tty_driver));
3658 driver->magic = TTY_DRIVER_MAGIC;
3659 driver->num = lines;
3660 /* later we'll move allocation of tables here */
3665 void put_tty_driver(struct tty_driver *driver)
3670 void tty_set_operations(struct tty_driver *driver,
3671 const struct tty_operations *op)
3673 driver->open = op->open;
3674 driver->close = op->close;
3675 driver->write = op->write;
3676 driver->put_char = op->put_char;
3677 driver->flush_chars = op->flush_chars;
3678 driver->write_room = op->write_room;
3679 driver->chars_in_buffer = op->chars_in_buffer;
3680 driver->ioctl = op->ioctl;
3681 driver->set_termios = op->set_termios;
3682 driver->throttle = op->throttle;
3683 driver->unthrottle = op->unthrottle;
3684 driver->stop = op->stop;
3685 driver->start = op->start;
3686 driver->hangup = op->hangup;
3687 driver->break_ctl = op->break_ctl;
3688 driver->flush_buffer = op->flush_buffer;
3689 driver->set_ldisc = op->set_ldisc;
3690 driver->wait_until_sent = op->wait_until_sent;
3691 driver->send_xchar = op->send_xchar;
3692 driver->read_proc = op->read_proc;
3693 driver->write_proc = op->write_proc;
3694 driver->tiocmget = op->tiocmget;
3695 driver->tiocmset = op->tiocmset;
3699 EXPORT_SYMBOL(alloc_tty_driver);
3700 EXPORT_SYMBOL(put_tty_driver);
3701 EXPORT_SYMBOL(tty_set_operations);
3704 * Called by a tty driver to register itself.
3706 int tty_register_driver(struct tty_driver *driver)
3713 if (driver->flags & TTY_DRIVER_INSTALLED)
3716 if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM) && driver->num) {
3717 p = kzalloc(driver->num * 3 * sizeof(void *), GFP_KERNEL);
3722 if (!driver->major) {
3723 error = alloc_chrdev_region(&dev, driver->minor_start, driver->num,
3726 driver->major = MAJOR(dev);
3727 driver->minor_start = MINOR(dev);
3730 dev = MKDEV(driver->major, driver->minor_start);
3731 error = register_chrdev_region(dev, driver->num, driver->name);
3739 driver->ttys = (struct tty_struct **)p;
3740 driver->termios = (struct ktermios **)(p + driver->num);
3741 driver->termios_locked = (struct ktermios **)(p + driver->num * 2);
3743 driver->ttys = NULL;
3744 driver->termios = NULL;
3745 driver->termios_locked = NULL;
3748 cdev_init(&driver->cdev, &tty_fops);
3749 driver->cdev.owner = driver->owner;
3750 error = cdev_add(&driver->cdev, dev, driver->num);
3752 unregister_chrdev_region(dev, driver->num);
3753 driver->ttys = NULL;
3754 driver->termios = driver->termios_locked = NULL;
3759 if (!driver->put_char)
3760 driver->put_char = tty_default_put_char;
3762 list_add(&driver->tty_drivers, &tty_drivers);
3764 if ( !(driver->flags & TTY_DRIVER_DYNAMIC_DEV) ) {
3765 for(i = 0; i < driver->num; i++)
3766 tty_register_device(driver, i, NULL);
3768 proc_tty_register_driver(driver);
3772 EXPORT_SYMBOL(tty_register_driver);
3775 * Called by a tty driver to unregister itself.
3777 int tty_unregister_driver(struct tty_driver *driver)
3780 struct ktermios *tp;
3783 if (driver->refcount)
3786 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3789 list_del(&driver->tty_drivers);
3792 * Free the termios and termios_locked structures because
3793 * we don't want to get memory leaks when modular tty
3794 * drivers are removed from the kernel.
3796 for (i = 0; i < driver->num; i++) {
3797 tp = driver->termios[i];
3799 driver->termios[i] = NULL;
3802 tp = driver->termios_locked[i];
3804 driver->termios_locked[i] = NULL;
3807 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3808 tty_unregister_device(driver, i);
3811 proc_tty_unregister_driver(driver);
3812 driver->ttys = NULL;
3813 driver->termios = driver->termios_locked = NULL;
3815 cdev_del(&driver->cdev);
3818 EXPORT_SYMBOL(tty_unregister_driver);
3820 dev_t tty_devnum(struct tty_struct *tty)
3822 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3824 EXPORT_SYMBOL(tty_devnum);
3826 void proc_clear_tty(struct task_struct *p)
3828 spin_lock_irq(&p->sighand->siglock);
3829 p->signal->tty = NULL;
3830 spin_unlock_irq(&p->sighand->siglock);
3833 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3836 /* We should not have a session or pgrp to here but.... */
3837 put_pid(tty->session);
3839 tty->session = get_pid(task_session(tsk));
3840 tty->pgrp = get_pid(task_pgrp(tsk));
3842 put_pid(tsk->signal->tty_old_pgrp);
3843 tsk->signal->tty = tty;
3844 tsk->signal->tty_old_pgrp = NULL;
3847 void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
3849 spin_lock_irq(&tsk->sighand->siglock);
3850 __proc_set_tty(tsk, tty);
3851 spin_unlock_irq(&tsk->sighand->siglock);
3854 struct tty_struct *get_current_tty(void)
3856 struct tty_struct *tty;
3857 WARN_ON_ONCE(!mutex_is_locked(&tty_mutex));
3858 tty = current->signal->tty;
3860 * session->tty can be changed/cleared from under us, make sure we
3861 * issue the load. The obtained pointer, when not NULL, is valid as
3862 * long as we hold tty_mutex.
3867 EXPORT_SYMBOL_GPL(get_current_tty);
3870 * Initialize the console device. This is called *early*, so
3871 * we can't necessarily depend on lots of kernel help here.
3872 * Just do some early initializations, and do the complex setup
3875 void __init console_init(void)
3879 /* Setup the default TTY line discipline. */
3880 (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY);
3883 * set up the console device so that later boot sequences can
3884 * inform about problems etc..
3886 call = __con_initcall_start;
3887 while (call < __con_initcall_end) {
3894 extern int vty_init(void);
3897 static int __init tty_class_init(void)
3899 tty_class = class_create(THIS_MODULE, "tty");
3900 if (IS_ERR(tty_class))
3901 return PTR_ERR(tty_class);
3905 postcore_initcall(tty_class_init);
3907 /* 3/2004 jmc: why do these devices exist? */
3909 static struct cdev tty_cdev, console_cdev;
3910 #ifdef CONFIG_UNIX98_PTYS
3911 static struct cdev ptmx_cdev;
3914 static struct cdev vc0_cdev;
3918 * Ok, now we can initialize the rest of the tty devices and can count
3919 * on memory allocations, interrupts etc..
3921 static int __init tty_init(void)
3923 cdev_init(&tty_cdev, &tty_fops);
3924 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3925 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3926 panic("Couldn't register /dev/tty driver\n");
3927 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), "tty");
3929 cdev_init(&console_cdev, &console_fops);
3930 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3931 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3932 panic("Couldn't register /dev/console driver\n");
3933 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 1), "console");
3935 #ifdef CONFIG_UNIX98_PTYS
3936 cdev_init(&ptmx_cdev, &ptmx_fops);
3937 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
3938 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
3939 panic("Couldn't register /dev/ptmx driver\n");
3940 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), "ptmx");
3944 cdev_init(&vc0_cdev, &console_fops);
3945 if (cdev_add(&vc0_cdev, MKDEV(TTY_MAJOR, 0), 1) ||
3946 register_chrdev_region(MKDEV(TTY_MAJOR, 0), 1, "/dev/vc/0") < 0)
3947 panic("Couldn't register /dev/tty0 driver\n");
3948 device_create(tty_class, NULL, MKDEV(TTY_MAJOR, 0), "tty0");
3954 module_init(tty_init);