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()
66 * -- Andrew Morton <andrewm@uow.edu.eu> 17Mar01
69 #include <linux/types.h>
70 #include <linux/major.h>
71 #include <linux/errno.h>
72 #include <linux/signal.h>
73 #include <linux/fcntl.h>
74 #include <linux/sched.h>
75 #include <linux/interrupt.h>
76 #include <linux/tty.h>
77 #include <linux/tty_driver.h>
78 #include <linux/tty_flip.h>
79 #include <linux/devpts_fs.h>
80 #include <linux/file.h>
81 #include <linux/fdtable.h>
82 #include <linux/console.h>
83 #include <linux/timer.h>
84 #include <linux/ctype.h>
87 #include <linux/string.h>
88 #include <linux/slab.h>
89 #include <linux/poll.h>
90 #include <linux/proc_fs.h>
91 #include <linux/init.h>
92 #include <linux/module.h>
93 #include <linux/smp_lock.h>
94 #include <linux/device.h>
95 #include <linux/wait.h>
96 #include <linux/bitops.h>
97 #include <linux/delay.h>
98 #include <linux/seq_file.h>
100 #include <linux/uaccess.h>
101 #include <asm/system.h>
103 #include <linux/kbd_kern.h>
104 #include <linux/vt_kern.h>
105 #include <linux/selection.h>
107 #include <linux/kmod.h>
108 #include <linux/nsproxy.h>
110 #undef TTY_DEBUG_HANGUP
112 #define TTY_PARANOIA_CHECK 1
113 #define CHECK_TTY_COUNT 1
115 struct ktermios tty_std_termios = { /* for the benefit of tty drivers */
116 .c_iflag = ICRNL | IXON,
117 .c_oflag = OPOST | ONLCR,
118 .c_cflag = B38400 | CS8 | CREAD | HUPCL,
119 .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
120 ECHOCTL | ECHOKE | IEXTEN,
126 EXPORT_SYMBOL(tty_std_termios);
128 /* This list gets poked at by procfs and various bits of boot up code. This
129 could do with some rationalisation such as pulling the tty proc function
132 LIST_HEAD(tty_drivers); /* linked list of tty drivers */
134 /* Mutex to protect creating and releasing a tty. This is shared with
135 vt.c for deeply disgusting hack reasons */
136 DEFINE_MUTEX(tty_mutex);
137 EXPORT_SYMBOL(tty_mutex);
139 #ifdef CONFIG_UNIX98_PTYS
140 extern struct tty_driver *ptm_driver; /* Unix98 pty masters; for /dev/ptmx */
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 *,
150 static unsigned int tty_poll(struct file *, poll_table *);
151 static int tty_open(struct inode *, struct file *);
152 static int tty_release(struct inode *, struct file *);
153 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
155 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
158 #define tty_compat_ioctl NULL
160 static int tty_fasync(int fd, struct file *filp, int on);
161 static void release_tty(struct tty_struct *tty, int idx);
162 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
163 static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
166 * alloc_tty_struct - allocate a tty object
168 * Return a new empty tty structure. The data fields have not
169 * been initialized in any way but has been zeroed
174 static struct tty_struct *alloc_tty_struct(void)
176 return kzalloc(sizeof(struct tty_struct), GFP_KERNEL);
179 static void tty_buffer_free_all(struct tty_struct *);
182 * free_tty_struct - free a disused tty
183 * @tty: tty struct to free
185 * Free the write buffers, tty queue and tty memory itself.
187 * Locking: none. Must be called after tty is definitely unused
190 static inline void free_tty_struct(struct tty_struct *tty)
192 kfree(tty->write_buf);
193 tty_buffer_free_all(tty);
197 #define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base)
200 * tty_name - return tty naming
201 * @tty: tty structure
202 * @buf: buffer for output
204 * Convert a tty structure into a name. The name reflects the kernel
205 * naming policy and if udev is in use may not reflect user space
210 char *tty_name(struct tty_struct *tty, char *buf)
212 if (!tty) /* Hmm. NULL pointer. That's fun. */
213 strcpy(buf, "NULL tty");
215 strcpy(buf, tty->name);
219 EXPORT_SYMBOL(tty_name);
221 int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
224 #ifdef TTY_PARANOIA_CHECK
227 "null TTY for (%d:%d) in %s\n",
228 imajor(inode), iminor(inode), routine);
231 if (tty->magic != TTY_MAGIC) {
233 "bad magic number for tty struct (%d:%d) in %s\n",
234 imajor(inode), iminor(inode), routine);
241 static int check_tty_count(struct tty_struct *tty, const char *routine)
243 #ifdef CHECK_TTY_COUNT
248 list_for_each(p, &tty->tty_files) {
252 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
253 tty->driver->subtype == PTY_TYPE_SLAVE &&
254 tty->link && tty->link->count)
256 if (tty->count != count) {
257 printk(KERN_WARNING "Warning: dev (%s) tty->count(%d) "
258 "!= #fd's(%d) in %s\n",
259 tty->name, tty->count, count, routine);
267 * Tty buffer allocation management
271 * tty_buffer_free_all - free buffers used by a tty
272 * @tty: tty to free from
274 * Remove all the buffers pending on a tty whether queued with data
275 * or in the free ring. Must be called when the tty is no longer in use
280 static void tty_buffer_free_all(struct tty_struct *tty)
282 struct tty_buffer *thead;
283 while ((thead = tty->buf.head) != NULL) {
284 tty->buf.head = thead->next;
287 while ((thead = tty->buf.free) != NULL) {
288 tty->buf.free = thead->next;
291 tty->buf.tail = NULL;
292 tty->buf.memory_used = 0;
296 * tty_buffer_init - prepare a tty buffer structure
297 * @tty: tty to initialise
299 * Set up the initial state of the buffer management for a tty device.
300 * Must be called before the other tty buffer functions are used.
305 static void tty_buffer_init(struct tty_struct *tty)
307 spin_lock_init(&tty->buf.lock);
308 tty->buf.head = NULL;
309 tty->buf.tail = NULL;
310 tty->buf.free = NULL;
311 tty->buf.memory_used = 0;
315 * tty_buffer_alloc - allocate a tty buffer
317 * @size: desired size (characters)
319 * Allocate a new tty buffer to hold the desired number of characters.
320 * Return NULL if out of memory or the allocation would exceed the
323 * Locking: Caller must hold tty->buf.lock
326 static struct tty_buffer *tty_buffer_alloc(struct tty_struct *tty, size_t size)
328 struct tty_buffer *p;
330 if (tty->buf.memory_used + size > 65536)
332 p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC);
340 p->char_buf_ptr = (char *)(p->data);
341 p->flag_buf_ptr = (unsigned char *)p->char_buf_ptr + size;
342 tty->buf.memory_used += size;
347 * tty_buffer_free - free a tty buffer
348 * @tty: tty owning the buffer
349 * @b: the buffer to free
351 * Free a tty buffer, or add it to the free list according to our
354 * Locking: Caller must hold tty->buf.lock
357 static void tty_buffer_free(struct tty_struct *tty, struct tty_buffer *b)
359 /* Dumb strategy for now - should keep some stats */
360 tty->buf.memory_used -= b->size;
361 WARN_ON(tty->buf.memory_used < 0);
366 b->next = tty->buf.free;
372 * __tty_buffer_flush - flush full tty buffers
375 * flush all the buffers containing receive data. Caller must
376 * hold the buffer lock and must have ensured no parallel flush to
379 * Locking: Caller must hold tty->buf.lock
382 static void __tty_buffer_flush(struct tty_struct *tty)
384 struct tty_buffer *thead;
386 while ((thead = tty->buf.head) != NULL) {
387 tty->buf.head = thead->next;
388 tty_buffer_free(tty, thead);
390 tty->buf.tail = NULL;
394 * tty_buffer_flush - flush full tty buffers
397 * flush all the buffers containing receive data. If the buffer is
398 * being processed by flush_to_ldisc then we defer the processing
404 static void tty_buffer_flush(struct tty_struct *tty)
407 spin_lock_irqsave(&tty->buf.lock, flags);
409 /* If the data is being pushed to the tty layer then we can't
410 process it here. Instead set a flag and the flush_to_ldisc
411 path will process the flush request before it exits */
412 if (test_bit(TTY_FLUSHING, &tty->flags)) {
413 set_bit(TTY_FLUSHPENDING, &tty->flags);
414 spin_unlock_irqrestore(&tty->buf.lock, flags);
415 wait_event(tty->read_wait,
416 test_bit(TTY_FLUSHPENDING, &tty->flags) == 0);
419 __tty_buffer_flush(tty);
420 spin_unlock_irqrestore(&tty->buf.lock, flags);
424 * tty_buffer_find - find a free tty buffer
425 * @tty: tty owning the buffer
426 * @size: characters wanted
428 * Locate an existing suitable tty buffer or if we are lacking one then
429 * allocate a new one. We round our buffers off in 256 character chunks
430 * to get better allocation behaviour.
432 * Locking: Caller must hold tty->buf.lock
435 static struct tty_buffer *tty_buffer_find(struct tty_struct *tty, size_t size)
437 struct tty_buffer **tbh = &tty->buf.free;
438 while ((*tbh) != NULL) {
439 struct tty_buffer *t = *tbh;
440 if (t->size >= size) {
446 tty->buf.memory_used += t->size;
449 tbh = &((*tbh)->next);
451 /* Round the buffer size out */
452 size = (size + 0xFF) & ~0xFF;
453 return tty_buffer_alloc(tty, size);
454 /* Should possibly check if this fails for the largest buffer we
455 have queued and recycle that ? */
459 * tty_buffer_request_room - grow tty buffer if needed
460 * @tty: tty structure
461 * @size: size desired
463 * Make at least size bytes of linear space available for the tty
464 * buffer. If we fail return the size we managed to find.
466 * Locking: Takes tty->buf.lock
468 int tty_buffer_request_room(struct tty_struct *tty, size_t size)
470 struct tty_buffer *b, *n;
474 spin_lock_irqsave(&tty->buf.lock, flags);
476 /* OPTIMISATION: We could keep a per tty "zero" sized buffer to
477 remove this conditional if its worth it. This would be invisible
479 if ((b = tty->buf.tail) != NULL)
480 left = b->size - b->used;
485 /* This is the slow path - looking for new buffers to use */
486 if ((n = tty_buffer_find(tty, size)) != NULL) {
497 spin_unlock_irqrestore(&tty->buf.lock, flags);
500 EXPORT_SYMBOL_GPL(tty_buffer_request_room);
503 * tty_insert_flip_string - Add characters to the tty buffer
504 * @tty: tty structure
508 * Queue a series of bytes to the tty buffering. All the characters
509 * passed are marked as without error. Returns the number added.
511 * Locking: Called functions may take tty->buf.lock
514 int tty_insert_flip_string(struct tty_struct *tty, const unsigned char *chars,
519 int space = tty_buffer_request_room(tty, size - copied);
520 struct tty_buffer *tb = tty->buf.tail;
521 /* If there is no space then tb may be NULL */
522 if (unlikely(space == 0))
524 memcpy(tb->char_buf_ptr + tb->used, chars, space);
525 memset(tb->flag_buf_ptr + tb->used, TTY_NORMAL, space);
529 /* There is a small chance that we need to split the data over
530 several buffers. If this is the case we must loop */
531 } while (unlikely(size > copied));
534 EXPORT_SYMBOL(tty_insert_flip_string);
537 * tty_insert_flip_string_flags - Add characters to the tty buffer
538 * @tty: tty structure
543 * Queue a series of bytes to the tty buffering. For each character
544 * the flags array indicates the status of the character. Returns the
547 * Locking: Called functions may take tty->buf.lock
550 int tty_insert_flip_string_flags(struct tty_struct *tty,
551 const unsigned char *chars, const char *flags, size_t size)
555 int space = tty_buffer_request_room(tty, size - copied);
556 struct tty_buffer *tb = tty->buf.tail;
557 /* If there is no space then tb may be NULL */
558 if (unlikely(space == 0))
560 memcpy(tb->char_buf_ptr + tb->used, chars, space);
561 memcpy(tb->flag_buf_ptr + tb->used, flags, space);
566 /* There is a small chance that we need to split the data over
567 several buffers. If this is the case we must loop */
568 } while (unlikely(size > copied));
571 EXPORT_SYMBOL(tty_insert_flip_string_flags);
574 * tty_schedule_flip - push characters to ldisc
575 * @tty: tty to push from
577 * Takes any pending buffers and transfers their ownership to the
578 * ldisc side of the queue. It then schedules those characters for
579 * processing by the line discipline.
581 * Locking: Takes tty->buf.lock
584 void tty_schedule_flip(struct tty_struct *tty)
587 spin_lock_irqsave(&tty->buf.lock, flags);
588 if (tty->buf.tail != NULL)
589 tty->buf.tail->commit = tty->buf.tail->used;
590 spin_unlock_irqrestore(&tty->buf.lock, flags);
591 schedule_delayed_work(&tty->buf.work, 1);
593 EXPORT_SYMBOL(tty_schedule_flip);
596 * tty_prepare_flip_string - make room for characters
598 * @chars: return pointer for character write area
599 * @size: desired size
601 * Prepare a block of space in the buffer for data. Returns the length
602 * available and buffer pointer to the space which is now allocated and
603 * accounted for as ready for normal characters. This is used for drivers
604 * that need their own block copy routines into the buffer. There is no
605 * guarantee the buffer is a DMA target!
607 * Locking: May call functions taking tty->buf.lock
610 int tty_prepare_flip_string(struct tty_struct *tty, unsigned char **chars,
613 int space = tty_buffer_request_room(tty, size);
615 struct tty_buffer *tb = tty->buf.tail;
616 *chars = tb->char_buf_ptr + tb->used;
617 memset(tb->flag_buf_ptr + tb->used, TTY_NORMAL, space);
623 EXPORT_SYMBOL_GPL(tty_prepare_flip_string);
626 * tty_prepare_flip_string_flags - make room for characters
628 * @chars: return pointer for character write area
629 * @flags: return pointer for status flag write area
630 * @size: desired size
632 * Prepare a block of space in the buffer for data. Returns the length
633 * available and buffer pointer to the space which is now allocated and
634 * accounted for as ready for characters. This is used for drivers
635 * that need their own block copy routines into the buffer. There is no
636 * guarantee the buffer is a DMA target!
638 * Locking: May call functions taking tty->buf.lock
641 int tty_prepare_flip_string_flags(struct tty_struct *tty,
642 unsigned char **chars, char **flags, size_t size)
644 int space = tty_buffer_request_room(tty, size);
646 struct tty_buffer *tb = tty->buf.tail;
647 *chars = tb->char_buf_ptr + tb->used;
648 *flags = tb->flag_buf_ptr + tb->used;
654 EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags);
659 * tty_set_termios_ldisc - set ldisc field
660 * @tty: tty structure
661 * @num: line discipline number
663 * This is probably overkill for real world processors but
664 * they are not on hot paths so a little discipline won't do
667 * Locking: takes termios_mutex
670 static void tty_set_termios_ldisc(struct tty_struct *tty, int num)
672 mutex_lock(&tty->termios_mutex);
673 tty->termios->c_line = num;
674 mutex_unlock(&tty->termios_mutex);
678 * This guards the refcounted line discipline lists. The lock
679 * must be taken with irqs off because there are hangup path
680 * callers who will do ldisc lookups and cannot sleep.
683 static DEFINE_SPINLOCK(tty_ldisc_lock);
684 static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_wait);
685 /* Line disc dispatch table */
686 static struct tty_ldisc_ops *tty_ldiscs[NR_LDISCS];
689 * tty_register_ldisc - install a line discipline
690 * @disc: ldisc number
691 * @new_ldisc: pointer to the ldisc object
693 * Installs a new line discipline into the kernel. The discipline
694 * is set up as unreferenced and then made available to the kernel
695 * from this point onwards.
698 * takes tty_ldisc_lock to guard against ldisc races
701 int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc)
706 if (disc < N_TTY || disc >= NR_LDISCS)
709 spin_lock_irqsave(&tty_ldisc_lock, flags);
710 tty_ldiscs[disc] = new_ldisc;
711 new_ldisc->num = disc;
712 new_ldisc->refcount = 0;
713 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
717 EXPORT_SYMBOL(tty_register_ldisc);
720 * tty_unregister_ldisc - unload a line discipline
721 * @disc: ldisc number
722 * @new_ldisc: pointer to the ldisc object
724 * Remove a line discipline from the kernel providing it is not
728 * takes tty_ldisc_lock to guard against ldisc races
731 int tty_unregister_ldisc(int disc)
736 if (disc < N_TTY || disc >= NR_LDISCS)
739 spin_lock_irqsave(&tty_ldisc_lock, flags);
740 if (tty_ldiscs[disc]->refcount)
743 tty_ldiscs[disc] = NULL;
744 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
748 EXPORT_SYMBOL(tty_unregister_ldisc);
752 * tty_ldisc_try_get - try and reference an ldisc
753 * @disc: ldisc number
754 * @ld: tty ldisc structure to complete
756 * Attempt to open and lock a line discipline into place. Return
757 * the line discipline refcounted and assigned in ld. On an error
758 * report the error code back
761 static int tty_ldisc_try_get(int disc, struct tty_ldisc *ld)
764 struct tty_ldisc_ops *ldops;
767 spin_lock_irqsave(&tty_ldisc_lock, flags);
769 ldops = tty_ldiscs[disc];
770 /* Check the entry is defined */
772 /* If the module is being unloaded we can't use it */
773 if (!try_module_get(ldops->owner))
782 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
787 * tty_ldisc_get - take a reference to an ldisc
788 * @disc: ldisc number
789 * @ld: tty line discipline structure to use
791 * Takes a reference to a line discipline. Deals with refcounts and
792 * module locking counts. Returns NULL if the discipline is not available.
793 * Returns a pointer to the discipline and bumps the ref count if it is
797 * takes tty_ldisc_lock to guard against ldisc races
800 static int tty_ldisc_get(int disc, struct tty_ldisc *ld)
804 if (disc < N_TTY || disc >= NR_LDISCS)
806 err = tty_ldisc_try_get(disc, ld);
807 if (err == -EAGAIN) {
808 request_module("tty-ldisc-%d", disc);
809 err = tty_ldisc_try_get(disc, ld);
815 * tty_ldisc_put - drop ldisc reference
816 * @disc: ldisc number
818 * Drop a reference to a line discipline. Manage refcounts and
819 * module usage counts
822 * takes tty_ldisc_lock to guard against ldisc races
825 static void tty_ldisc_put(struct tty_ldisc_ops *ld)
830 BUG_ON(disc < N_TTY || disc >= NR_LDISCS);
832 spin_lock_irqsave(&tty_ldisc_lock, flags);
833 ld = tty_ldiscs[disc];
834 BUG_ON(ld->refcount == 0);
836 module_put(ld->owner);
837 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
840 static void * tty_ldiscs_seq_start(struct seq_file *m, loff_t *pos)
842 return (*pos < NR_LDISCS) ? pos : NULL;
845 static void * tty_ldiscs_seq_next(struct seq_file *m, void *v, loff_t *pos)
848 return (*pos < NR_LDISCS) ? pos : NULL;
851 static void tty_ldiscs_seq_stop(struct seq_file *m, void *v)
855 static int tty_ldiscs_seq_show(struct seq_file *m, void *v)
857 int i = *(loff_t *)v;
860 if (tty_ldisc_get(i, &ld) < 0)
862 seq_printf(m, "%-10s %2d\n", ld.ops->name ? ld.ops->name : "???", i);
863 tty_ldisc_put(ld.ops);
867 static const struct seq_operations tty_ldiscs_seq_ops = {
868 .start = tty_ldiscs_seq_start,
869 .next = tty_ldiscs_seq_next,
870 .stop = tty_ldiscs_seq_stop,
871 .show = tty_ldiscs_seq_show,
874 static int proc_tty_ldiscs_open(struct inode *inode, struct file *file)
876 return seq_open(file, &tty_ldiscs_seq_ops);
879 const struct file_operations tty_ldiscs_proc_fops = {
880 .owner = THIS_MODULE,
881 .open = proc_tty_ldiscs_open,
884 .release = seq_release,
888 * tty_ldisc_assign - set ldisc on a tty
889 * @tty: tty to assign
890 * @ld: line discipline
892 * Install an instance of a line discipline into a tty structure. The
893 * ldisc must have a reference count above zero to ensure it remains/
894 * The tty instance refcount starts at zero.
897 * Caller must hold references
900 static void tty_ldisc_assign(struct tty_struct *tty, struct tty_ldisc *ld)
907 * tty_ldisc_try - internal helper
910 * Make a single attempt to grab and bump the refcount on
911 * the tty ldisc. Return 0 on failure or 1 on success. This is
912 * used to implement both the waiting and non waiting versions
915 * Locking: takes tty_ldisc_lock
918 static int tty_ldisc_try(struct tty_struct *tty)
921 struct tty_ldisc *ld;
924 spin_lock_irqsave(&tty_ldisc_lock, flags);
926 if (test_bit(TTY_LDISC, &tty->flags)) {
930 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
935 * tty_ldisc_ref_wait - wait for the tty ldisc
938 * Dereference the line discipline for the terminal and take a
939 * reference to it. If the line discipline is in flux then
940 * wait patiently until it changes.
942 * Note: Must not be called from an IRQ/timer context. The caller
943 * must also be careful not to hold other locks that will deadlock
944 * against a discipline change, such as an existing ldisc reference
945 * (which we check for)
947 * Locking: call functions take tty_ldisc_lock
950 struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty)
952 /* wait_event is a macro */
953 wait_event(tty_ldisc_wait, tty_ldisc_try(tty));
954 if (tty->ldisc.refcount == 0)
955 printk(KERN_ERR "tty_ldisc_ref_wait\n");
959 EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait);
962 * tty_ldisc_ref - get the tty ldisc
965 * Dereference the line discipline for the terminal and take a
966 * reference to it. If the line discipline is in flux then
967 * return NULL. Can be called from IRQ and timer functions.
969 * Locking: called functions take tty_ldisc_lock
972 struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty)
974 if (tty_ldisc_try(tty))
979 EXPORT_SYMBOL_GPL(tty_ldisc_ref);
982 * tty_ldisc_deref - free a tty ldisc reference
983 * @ld: reference to free up
985 * Undoes the effect of tty_ldisc_ref or tty_ldisc_ref_wait. May
986 * be called in IRQ context.
988 * Locking: takes tty_ldisc_lock
991 void tty_ldisc_deref(struct tty_ldisc *ld)
997 spin_lock_irqsave(&tty_ldisc_lock, flags);
998 if (ld->refcount == 0)
999 printk(KERN_ERR "tty_ldisc_deref: no references.\n");
1002 if (ld->refcount == 0)
1003 wake_up(&tty_ldisc_wait);
1004 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
1007 EXPORT_SYMBOL_GPL(tty_ldisc_deref);
1010 * tty_ldisc_enable - allow ldisc use
1011 * @tty: terminal to activate ldisc on
1013 * Set the TTY_LDISC flag when the line discipline can be called
1014 * again. Do necessary wakeups for existing sleepers.
1016 * Note: nobody should set this bit except via this function. Clearing
1017 * directly is allowed.
1020 static void tty_ldisc_enable(struct tty_struct *tty)
1022 set_bit(TTY_LDISC, &tty->flags);
1023 wake_up(&tty_ldisc_wait);
1027 * tty_ldisc_restore - helper for tty ldisc change
1028 * @tty: tty to recover
1029 * @old: previous ldisc
1031 * Restore the previous line discipline or N_TTY when a line discipline
1032 * change fails due to an open error
1035 static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old)
1038 struct tty_ldisc new_ldisc;
1040 /* There is an outstanding reference here so this is safe */
1041 tty_ldisc_get(old->ops->num, old);
1042 tty_ldisc_assign(tty, old);
1043 tty_set_termios_ldisc(tty, old->ops->num);
1044 if (old->ops->open && (old->ops->open(tty) < 0)) {
1045 tty_ldisc_put(old->ops);
1046 /* This driver is always present */
1047 if (tty_ldisc_get(N_TTY, &new_ldisc) < 0)
1048 panic("n_tty: get");
1049 tty_ldisc_assign(tty, &new_ldisc);
1050 tty_set_termios_ldisc(tty, N_TTY);
1051 if (new_ldisc.ops->open) {
1052 int r = new_ldisc.ops->open(tty);
1054 panic("Couldn't open N_TTY ldisc for "
1056 tty_name(tty, buf), r);
1062 * tty_set_ldisc - set line discipline
1063 * @tty: the terminal to set
1064 * @ldisc: the line discipline
1066 * Set the discipline of a tty line. Must be called from a process
1069 * Locking: takes tty_ldisc_lock.
1070 * called functions take termios_mutex
1073 static int tty_set_ldisc(struct tty_struct *tty, int ldisc)
1076 struct tty_ldisc o_ldisc, new_ldisc;
1078 unsigned long flags;
1079 struct tty_struct *o_tty;
1082 /* This is a bit ugly for now but means we can break the 'ldisc
1083 is part of the tty struct' assumption later */
1084 retval = tty_ldisc_get(ldisc, &new_ldisc);
1089 * Problem: What do we do if this blocks ?
1092 tty_wait_until_sent(tty, 0);
1094 if (tty->ldisc.ops->num == ldisc) {
1095 tty_ldisc_put(new_ldisc.ops);
1100 * No more input please, we are switching. The new ldisc
1101 * will update this value in the ldisc open function
1104 tty->receive_room = 0;
1106 o_ldisc = tty->ldisc;
1110 * Make sure we don't change while someone holds a
1111 * reference to the line discipline. The TTY_LDISC bit
1112 * prevents anyone taking a reference once it is clear.
1113 * We need the lock to avoid racing reference takers.
1116 spin_lock_irqsave(&tty_ldisc_lock, flags);
1117 if (tty->ldisc.refcount || (o_tty && o_tty->ldisc.refcount)) {
1118 if (tty->ldisc.refcount) {
1119 /* Free the new ldisc we grabbed. Must drop the lock
1121 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
1122 tty_ldisc_put(o_ldisc.ops);
1124 * There are several reasons we may be busy, including
1125 * random momentary I/O traffic. We must therefore
1126 * retry. We could distinguish between blocking ops
1127 * and retries if we made tty_ldisc_wait() smarter.
1128 * That is up for discussion.
1130 if (wait_event_interruptible(tty_ldisc_wait, tty->ldisc.refcount == 0) < 0)
1131 return -ERESTARTSYS;
1134 if (o_tty && o_tty->ldisc.refcount) {
1135 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
1136 tty_ldisc_put(o_tty->ldisc.ops);
1137 if (wait_event_interruptible(tty_ldisc_wait, o_tty->ldisc.refcount == 0) < 0)
1138 return -ERESTARTSYS;
1143 * If the TTY_LDISC bit is set, then we are racing against
1144 * another ldisc change
1146 if (!test_bit(TTY_LDISC, &tty->flags)) {
1147 struct tty_ldisc *ld;
1148 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
1149 tty_ldisc_put(new_ldisc.ops);
1150 ld = tty_ldisc_ref_wait(tty);
1151 tty_ldisc_deref(ld);
1155 clear_bit(TTY_LDISC, &tty->flags);
1157 clear_bit(TTY_LDISC, &o_tty->flags);
1158 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
1161 * From this point on we know nobody has an ldisc
1162 * usage reference, nor can they obtain one until
1163 * we say so later on.
1166 work = cancel_delayed_work(&tty->buf.work);
1168 * Wait for ->hangup_work and ->buf.work handlers to terminate
1169 * MUST NOT hold locks here.
1171 flush_scheduled_work();
1172 /* Shutdown the current discipline. */
1173 if (o_ldisc.ops->close)
1174 (o_ldisc.ops->close)(tty);
1176 /* Now set up the new line discipline. */
1177 tty_ldisc_assign(tty, &new_ldisc);
1178 tty_set_termios_ldisc(tty, ldisc);
1179 if (new_ldisc.ops->open)
1180 retval = (new_ldisc.ops->open)(tty);
1182 tty_ldisc_put(new_ldisc.ops);
1183 tty_ldisc_restore(tty, &o_ldisc);
1185 /* At this point we hold a reference to the new ldisc and a
1186 a reference to the old ldisc. If we ended up flipping back
1187 to the existing ldisc we have two references to it */
1189 if (tty->ldisc.ops->num != o_ldisc.ops->num && tty->ops->set_ldisc)
1190 tty->ops->set_ldisc(tty);
1192 tty_ldisc_put(o_ldisc.ops);
1195 * Allow ldisc referencing to occur as soon as the driver
1196 * ldisc callback completes.
1199 tty_ldisc_enable(tty);
1201 tty_ldisc_enable(o_tty);
1203 /* Restart it in case no characters kick it off. Safe if
1206 schedule_delayed_work(&tty->buf.work, 1);
1211 * get_tty_driver - find device of a tty
1212 * @dev_t: device identifier
1213 * @index: returns the index of the tty
1215 * This routine returns a tty driver structure, given a device number
1216 * and also passes back the index number.
1218 * Locking: caller must hold tty_mutex
1221 static struct tty_driver *get_tty_driver(dev_t device, int *index)
1223 struct tty_driver *p;
1225 list_for_each_entry(p, &tty_drivers, tty_drivers) {
1226 dev_t base = MKDEV(p->major, p->minor_start);
1227 if (device < base || device >= base + p->num)
1229 *index = device - base;
1235 #ifdef CONFIG_CONSOLE_POLL
1238 * tty_find_polling_driver - find device of a polled tty
1239 * @name: name string to match
1240 * @line: pointer to resulting tty line nr
1242 * This routine returns a tty driver structure, given a name
1243 * and the condition that the tty driver is capable of polled
1246 struct tty_driver *tty_find_polling_driver(char *name, int *line)
1248 struct tty_driver *p, *res = NULL;
1252 mutex_lock(&tty_mutex);
1253 /* Search through the tty devices to look for a match */
1254 list_for_each_entry(p, &tty_drivers, tty_drivers) {
1255 str = name + strlen(p->name);
1256 tty_line = simple_strtoul(str, &str, 10);
1262 if (tty_line >= 0 && tty_line <= p->num && p->ops &&
1263 p->ops->poll_init && !p->ops->poll_init(p, tty_line, str)) {
1269 mutex_unlock(&tty_mutex);
1273 EXPORT_SYMBOL_GPL(tty_find_polling_driver);
1277 * tty_check_change - check for POSIX terminal changes
1278 * @tty: tty to check
1280 * If we try to write to, or set the state of, a terminal and we're
1281 * not in the foreground, send a SIGTTOU. If the signal is blocked or
1282 * ignored, go ahead and perform the operation. (POSIX 7.2)
1284 * Locking: ctrl_lock
1287 int tty_check_change(struct tty_struct *tty)
1289 unsigned long flags;
1292 if (current->signal->tty != tty)
1295 spin_lock_irqsave(&tty->ctrl_lock, flags);
1298 printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");
1301 if (task_pgrp(current) == tty->pgrp)
1303 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
1304 if (is_ignored(SIGTTOU))
1306 if (is_current_pgrp_orphaned()) {
1310 kill_pgrp(task_pgrp(current), SIGTTOU, 1);
1311 set_thread_flag(TIF_SIGPENDING);
1316 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
1320 EXPORT_SYMBOL(tty_check_change);
1322 static ssize_t hung_up_tty_read(struct file *file, char __user *buf,
1323 size_t count, loff_t *ppos)
1328 static ssize_t hung_up_tty_write(struct file *file, const char __user *buf,
1329 size_t count, loff_t *ppos)
1334 /* No kernel lock held - none needed ;) */
1335 static unsigned int hung_up_tty_poll(struct file *filp, poll_table *wait)
1337 return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM;
1340 static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
1343 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
1346 static long hung_up_tty_compat_ioctl(struct file *file,
1347 unsigned int cmd, unsigned long arg)
1349 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
1352 static const struct file_operations tty_fops = {
1353 .llseek = no_llseek,
1357 .unlocked_ioctl = tty_ioctl,
1358 .compat_ioctl = tty_compat_ioctl,
1360 .release = tty_release,
1361 .fasync = tty_fasync,
1364 #ifdef CONFIG_UNIX98_PTYS
1365 static const struct file_operations ptmx_fops = {
1366 .llseek = no_llseek,
1370 .unlocked_ioctl = tty_ioctl,
1371 .compat_ioctl = tty_compat_ioctl,
1373 .release = tty_release,
1374 .fasync = tty_fasync,
1378 static const struct file_operations console_fops = {
1379 .llseek = no_llseek,
1381 .write = redirected_tty_write,
1383 .unlocked_ioctl = tty_ioctl,
1384 .compat_ioctl = tty_compat_ioctl,
1386 .release = tty_release,
1387 .fasync = tty_fasync,
1390 static const struct file_operations hung_up_tty_fops = {
1391 .llseek = no_llseek,
1392 .read = hung_up_tty_read,
1393 .write = hung_up_tty_write,
1394 .poll = hung_up_tty_poll,
1395 .unlocked_ioctl = hung_up_tty_ioctl,
1396 .compat_ioctl = hung_up_tty_compat_ioctl,
1397 .release = tty_release,
1400 static DEFINE_SPINLOCK(redirect_lock);
1401 static struct file *redirect;
1404 * tty_wakeup - request more data
1407 * Internal and external helper for wakeups of tty. This function
1408 * informs the line discipline if present that the driver is ready
1409 * to receive more output data.
1412 void tty_wakeup(struct tty_struct *tty)
1414 struct tty_ldisc *ld;
1416 if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
1417 ld = tty_ldisc_ref(tty);
1419 if (ld->ops->write_wakeup)
1420 ld->ops->write_wakeup(tty);
1421 tty_ldisc_deref(ld);
1424 wake_up_interruptible(&tty->write_wait);
1427 EXPORT_SYMBOL_GPL(tty_wakeup);
1430 * tty_ldisc_flush - flush line discipline queue
1433 * Flush the line discipline queue (if any) for this tty. If there
1434 * is no line discipline active this is a no-op.
1437 void tty_ldisc_flush(struct tty_struct *tty)
1439 struct tty_ldisc *ld = tty_ldisc_ref(tty);
1441 if (ld->ops->flush_buffer)
1442 ld->ops->flush_buffer(tty);
1443 tty_ldisc_deref(ld);
1445 tty_buffer_flush(tty);
1448 EXPORT_SYMBOL_GPL(tty_ldisc_flush);
1451 * tty_reset_termios - reset terminal state
1452 * @tty: tty to reset
1454 * Restore a terminal to the driver default state
1457 static void tty_reset_termios(struct tty_struct *tty)
1459 mutex_lock(&tty->termios_mutex);
1460 *tty->termios = tty->driver->init_termios;
1461 tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
1462 tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
1463 mutex_unlock(&tty->termios_mutex);
1467 * do_tty_hangup - actual handler for hangup events
1470 k * This can be called by the "eventd" kernel thread. That is process
1471 * synchronous but doesn't hold any locks, so we need to make sure we
1472 * have the appropriate locks for what we're doing.
1474 * The hangup event clears any pending redirections onto the hung up
1475 * device. It ensures future writes will error and it does the needed
1476 * line discipline hangup and signal delivery. The tty object itself
1481 * redirect lock for undoing redirection
1482 * file list lock for manipulating list of ttys
1483 * tty_ldisc_lock from called functions
1484 * termios_mutex resetting termios data
1485 * tasklist_lock to walk task list for hangup event
1486 * ->siglock to protect ->signal/->sighand
1488 static void do_tty_hangup(struct work_struct *work)
1490 struct tty_struct *tty =
1491 container_of(work, struct tty_struct, hangup_work);
1492 struct file *cons_filp = NULL;
1493 struct file *filp, *f = NULL;
1494 struct task_struct *p;
1495 struct tty_ldisc *ld;
1496 int closecount = 0, n;
1497 unsigned long flags;
1502 /* inuse_filps is protected by the single kernel lock */
1505 spin_lock(&redirect_lock);
1506 if (redirect && redirect->private_data == tty) {
1510 spin_unlock(&redirect_lock);
1512 check_tty_count(tty, "do_tty_hangup");
1514 /* This breaks for file handles being sent over AF_UNIX sockets ? */
1515 list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) {
1516 if (filp->f_op->write == redirected_tty_write)
1518 if (filp->f_op->write != tty_write)
1521 tty_fasync(-1, filp, 0); /* can't block */
1522 filp->f_op = &hung_up_tty_fops;
1526 * FIXME! What are the locking issues here? This may me overdoing
1527 * things... This question is especially important now that we've
1528 * removed the irqlock.
1530 ld = tty_ldisc_ref(tty);
1532 /* We may have no line discipline at this point */
1533 if (ld->ops->flush_buffer)
1534 ld->ops->flush_buffer(tty);
1535 tty_driver_flush_buffer(tty);
1536 if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) &&
1537 ld->ops->write_wakeup)
1538 ld->ops->write_wakeup(tty);
1539 if (ld->ops->hangup)
1540 ld->ops->hangup(tty);
1543 * FIXME: Once we trust the LDISC code better we can wait here for
1544 * ldisc completion and fix the driver call race
1546 wake_up_interruptible(&tty->write_wait);
1547 wake_up_interruptible(&tty->read_wait);
1549 * Shutdown the current line discipline, and reset it to
1552 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1553 tty_reset_termios(tty);
1554 /* Defer ldisc switch */
1555 /* tty_deferred_ldisc_switch(N_TTY);
1557 This should get done automatically when the port closes and
1558 tty_release is called */
1560 read_lock(&tasklist_lock);
1562 do_each_pid_task(tty->session, PIDTYPE_SID, p) {
1563 spin_lock_irq(&p->sighand->siglock);
1564 if (p->signal->tty == tty)
1565 p->signal->tty = NULL;
1566 if (!p->signal->leader) {
1567 spin_unlock_irq(&p->sighand->siglock);
1570 __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
1571 __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
1572 put_pid(p->signal->tty_old_pgrp); /* A noop */
1573 spin_lock_irqsave(&tty->ctrl_lock, flags);
1575 p->signal->tty_old_pgrp = get_pid(tty->pgrp);
1576 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
1577 spin_unlock_irq(&p->sighand->siglock);
1578 } while_each_pid_task(tty->session, PIDTYPE_SID, p);
1580 read_unlock(&tasklist_lock);
1582 spin_lock_irqsave(&tty->ctrl_lock, flags);
1584 put_pid(tty->session);
1586 tty->session = NULL;
1588 tty->ctrl_status = 0;
1589 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
1592 * If one of the devices matches a console pointer, we
1593 * cannot just call hangup() because that will cause
1594 * tty->count and state->count to go out of sync.
1595 * So we just call close() the right number of times.
1598 if (tty->ops->close)
1599 for (n = 0; n < closecount; n++)
1600 tty->ops->close(tty, cons_filp);
1601 } else if (tty->ops->hangup)
1602 (tty->ops->hangup)(tty);
1604 * We don't want to have driver/ldisc interactions beyond
1605 * the ones we did here. The driver layer expects no
1606 * calls after ->hangup() from the ldisc side. However we
1607 * can't yet guarantee all that.
1609 set_bit(TTY_HUPPED, &tty->flags);
1611 tty_ldisc_enable(tty);
1612 tty_ldisc_deref(ld);
1620 * tty_hangup - trigger a hangup event
1621 * @tty: tty to hangup
1623 * A carrier loss (virtual or otherwise) has occurred on this like
1624 * schedule a hangup sequence to run after this event.
1627 void tty_hangup(struct tty_struct *tty)
1629 #ifdef TTY_DEBUG_HANGUP
1631 printk(KERN_DEBUG "%s hangup...\n", tty_name(tty, buf));
1633 schedule_work(&tty->hangup_work);
1636 EXPORT_SYMBOL(tty_hangup);
1639 * tty_vhangup - process vhangup
1640 * @tty: tty to hangup
1642 * The user has asked via system call for the terminal to be hung up.
1643 * We do this synchronously so that when the syscall returns the process
1644 * is complete. That guarantee is necessary for security reasons.
1647 void tty_vhangup(struct tty_struct *tty)
1649 #ifdef TTY_DEBUG_HANGUP
1652 printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf));
1654 do_tty_hangup(&tty->hangup_work);
1657 EXPORT_SYMBOL(tty_vhangup);
1660 * tty_hung_up_p - was tty hung up
1661 * @filp: file pointer of tty
1663 * Return true if the tty has been subject to a vhangup or a carrier
1667 int tty_hung_up_p(struct file *filp)
1669 return (filp->f_op == &hung_up_tty_fops);
1672 EXPORT_SYMBOL(tty_hung_up_p);
1675 * is_tty - checker whether file is a TTY
1676 * @filp: file handle that may be a tty
1678 * Check if the file handle is a tty handle.
1681 int is_tty(struct file *filp)
1683 return filp->f_op->read == tty_read
1684 || filp->f_op->read == hung_up_tty_read;
1687 static void session_clear_tty(struct pid *session)
1689 struct task_struct *p;
1690 do_each_pid_task(session, PIDTYPE_SID, p) {
1692 } while_each_pid_task(session, PIDTYPE_SID, p);
1696 * disassociate_ctty - disconnect controlling tty
1697 * @on_exit: true if exiting so need to "hang up" the session
1699 * This function is typically called only by the session leader, when
1700 * it wants to disassociate itself from its controlling tty.
1702 * It performs the following functions:
1703 * (1) Sends a SIGHUP and SIGCONT to the foreground process group
1704 * (2) Clears the tty from being controlling the session
1705 * (3) Clears the controlling tty for all processes in the
1708 * The argument on_exit is set to 1 if called when a process is
1709 * exiting; it is 0 if called by the ioctl TIOCNOTTY.
1712 * BKL is taken for hysterical raisins
1713 * tty_mutex is taken to protect tty
1714 * ->siglock is taken to protect ->signal/->sighand
1715 * tasklist_lock is taken to walk process list for sessions
1716 * ->siglock is taken to protect ->signal/->sighand
1719 void disassociate_ctty(int on_exit)
1721 struct tty_struct *tty;
1722 struct pid *tty_pgrp = NULL;
1725 mutex_lock(&tty_mutex);
1726 tty = get_current_tty();
1728 tty_pgrp = get_pid(tty->pgrp);
1729 mutex_unlock(&tty_mutex);
1731 /* XXX: here we race, there is nothing protecting tty */
1732 if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)
1735 } else if (on_exit) {
1736 struct pid *old_pgrp;
1737 spin_lock_irq(¤t->sighand->siglock);
1738 old_pgrp = current->signal->tty_old_pgrp;
1739 current->signal->tty_old_pgrp = NULL;
1740 spin_unlock_irq(¤t->sighand->siglock);
1742 kill_pgrp(old_pgrp, SIGHUP, on_exit);
1743 kill_pgrp(old_pgrp, SIGCONT, on_exit);
1746 mutex_unlock(&tty_mutex);
1750 kill_pgrp(tty_pgrp, SIGHUP, on_exit);
1752 kill_pgrp(tty_pgrp, SIGCONT, on_exit);
1756 spin_lock_irq(¤t->sighand->siglock);
1757 put_pid(current->signal->tty_old_pgrp);
1758 current->signal->tty_old_pgrp = NULL;
1759 spin_unlock_irq(¤t->sighand->siglock);
1761 mutex_lock(&tty_mutex);
1762 /* It is possible that do_tty_hangup has free'd this tty */
1763 tty = get_current_tty();
1765 unsigned long flags;
1766 spin_lock_irqsave(&tty->ctrl_lock, flags);
1767 put_pid(tty->session);
1769 tty->session = NULL;
1771 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
1773 #ifdef TTY_DEBUG_HANGUP
1774 printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
1778 mutex_unlock(&tty_mutex);
1780 /* Now clear signal->tty under the lock */
1781 read_lock(&tasklist_lock);
1782 session_clear_tty(task_session(current));
1783 read_unlock(&tasklist_lock);
1788 * no_tty - Ensure the current process does not have a controlling tty
1792 struct task_struct *tsk = current;
1794 if (tsk->signal->leader)
1795 disassociate_ctty(0);
1797 proc_clear_tty(tsk);
1802 * stop_tty - propagate flow control
1805 * Perform flow control to the driver. For PTY/TTY pairs we
1806 * must also propagate the TIOCKPKT status. May be called
1807 * on an already stopped device and will not re-call the driver
1810 * This functionality is used by both the line disciplines for
1811 * halting incoming flow and by the driver. It may therefore be
1812 * called from any context, may be under the tty atomic_write_lock
1816 * Uses the tty control lock internally
1819 void stop_tty(struct tty_struct *tty)
1821 unsigned long flags;
1822 spin_lock_irqsave(&tty->ctrl_lock, flags);
1824 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
1828 if (tty->link && tty->link->packet) {
1829 tty->ctrl_status &= ~TIOCPKT_START;
1830 tty->ctrl_status |= TIOCPKT_STOP;
1831 wake_up_interruptible(&tty->link->read_wait);
1833 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
1835 (tty->ops->stop)(tty);
1838 EXPORT_SYMBOL(stop_tty);
1841 * start_tty - propagate flow control
1842 * @tty: tty to start
1844 * Start a tty that has been stopped if at all possible. Perform
1845 * any necessary wakeups and propagate the TIOCPKT status. If this
1846 * is the tty was previous stopped and is being started then the
1847 * driver start method is invoked and the line discipline woken.
1853 void start_tty(struct tty_struct *tty)
1855 unsigned long flags;
1856 spin_lock_irqsave(&tty->ctrl_lock, flags);
1857 if (!tty->stopped || tty->flow_stopped) {
1858 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
1862 if (tty->link && tty->link->packet) {
1863 tty->ctrl_status &= ~TIOCPKT_STOP;
1864 tty->ctrl_status |= TIOCPKT_START;
1865 wake_up_interruptible(&tty->link->read_wait);
1867 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
1868 if (tty->ops->start)
1869 (tty->ops->start)(tty);
1870 /* If we have a running line discipline it may need kicking */
1874 EXPORT_SYMBOL(start_tty);
1877 * tty_read - read method for tty device files
1878 * @file: pointer to tty file
1880 * @count: size of user buffer
1883 * Perform the read system call function on this terminal device. Checks
1884 * for hung up devices before calling the line discipline method.
1887 * Locks the line discipline internally while needed. Multiple
1888 * read calls may be outstanding in parallel.
1891 static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
1895 struct tty_struct *tty;
1896 struct inode *inode;
1897 struct tty_ldisc *ld;
1899 tty = (struct tty_struct *)file->private_data;
1900 inode = file->f_path.dentry->d_inode;
1901 if (tty_paranoia_check(tty, inode, "tty_read"))
1903 if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags)))
1906 /* We want to wait for the line discipline to sort out in this
1908 ld = tty_ldisc_ref_wait(tty);
1910 i = (ld->ops->read)(tty, file, buf, count);
1913 tty_ldisc_deref(ld);
1915 inode->i_atime = current_fs_time(inode->i_sb);
1919 void tty_write_unlock(struct tty_struct *tty)
1921 mutex_unlock(&tty->atomic_write_lock);
1922 wake_up_interruptible(&tty->write_wait);
1925 int tty_write_lock(struct tty_struct *tty, int ndelay)
1927 if (!mutex_trylock(&tty->atomic_write_lock)) {
1930 if (mutex_lock_interruptible(&tty->atomic_write_lock))
1931 return -ERESTARTSYS;
1937 * Split writes up in sane blocksizes to avoid
1938 * denial-of-service type attacks
1940 static inline ssize_t do_tty_write(
1941 ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
1942 struct tty_struct *tty,
1944 const char __user *buf,
1947 ssize_t ret, written = 0;
1950 ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
1955 * We chunk up writes into a temporary buffer. This
1956 * simplifies low-level drivers immensely, since they
1957 * don't have locking issues and user mode accesses.
1959 * But if TTY_NO_WRITE_SPLIT is set, we should use a
1962 * The default chunk-size is 2kB, because the NTTY
1963 * layer has problems with bigger chunks. It will
1964 * claim to be able to handle more characters than
1967 * FIXME: This can probably go away now except that 64K chunks
1968 * are too likely to fail unless switched to vmalloc...
1971 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
1976 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
1977 if (tty->write_cnt < chunk) {
1983 buf = kmalloc(chunk, GFP_KERNEL);
1988 kfree(tty->write_buf);
1989 tty->write_cnt = chunk;
1990 tty->write_buf = buf;
1993 /* Do the write .. */
1995 size_t size = count;
1999 if (copy_from_user(tty->write_buf, buf, size))
2001 ret = write(tty, file, tty->write_buf, size);
2010 if (signal_pending(current))
2015 struct inode *inode = file->f_path.dentry->d_inode;
2016 inode->i_mtime = current_fs_time(inode->i_sb);
2020 tty_write_unlock(tty);
2026 * tty_write - write method for tty device file
2027 * @file: tty file pointer
2028 * @buf: user data to write
2029 * @count: bytes to write
2032 * Write data to a tty device via the line discipline.
2035 * Locks the line discipline as required
2036 * Writes to the tty driver are serialized by the atomic_write_lock
2037 * and are then processed in chunks to the device. The line discipline
2038 * write method will not be involked in parallel for each device
2039 * The line discipline write method is called under the big
2040 * kernel lock for historical reasons. New code should not rely on this.
2043 static ssize_t tty_write(struct file *file, const char __user *buf,
2044 size_t count, loff_t *ppos)
2046 struct tty_struct *tty;
2047 struct inode *inode = file->f_path.dentry->d_inode;
2049 struct tty_ldisc *ld;
2051 tty = (struct tty_struct *)file->private_data;
2052 if (tty_paranoia_check(tty, inode, "tty_write"))
2054 if (!tty || !tty->ops->write ||
2055 (test_bit(TTY_IO_ERROR, &tty->flags)))
2057 /* Short term debug to catch buggy drivers */
2058 if (tty->ops->write_room == NULL)
2059 printk(KERN_ERR "tty driver %s lacks a write_room method.\n",
2061 ld = tty_ldisc_ref_wait(tty);
2062 if (!ld->ops->write)
2065 ret = do_tty_write(ld->ops->write, tty, file, buf, count);
2066 tty_ldisc_deref(ld);
2070 ssize_t redirected_tty_write(struct file *file, const char __user *buf,
2071 size_t count, loff_t *ppos)
2073 struct file *p = NULL;
2075 spin_lock(&redirect_lock);
2080 spin_unlock(&redirect_lock);
2084 res = vfs_write(p, buf, count, &p->f_pos);
2088 return tty_write(file, buf, count, ppos);
2091 void tty_port_init(struct tty_port *port)
2093 memset(port, 0, sizeof(*port));
2094 init_waitqueue_head(&port->open_wait);
2095 init_waitqueue_head(&port->close_wait);
2096 mutex_init(&port->mutex);
2098 EXPORT_SYMBOL(tty_port_init);
2100 int tty_port_alloc_xmit_buf(struct tty_port *port)
2102 /* We may sleep in get_zeroed_page() */
2103 mutex_lock(&port->mutex);
2104 if (port->xmit_buf == NULL)
2105 port->xmit_buf = (unsigned char *)get_zeroed_page(GFP_KERNEL);
2106 mutex_unlock(&port->mutex);
2107 if (port->xmit_buf == NULL)
2111 EXPORT_SYMBOL(tty_port_alloc_xmit_buf);
2113 void tty_port_free_xmit_buf(struct tty_port *port)
2115 mutex_lock(&port->mutex);
2116 if (port->xmit_buf != NULL) {
2117 free_page((unsigned long)port->xmit_buf);
2118 port->xmit_buf = NULL;
2120 mutex_unlock(&port->mutex);
2122 EXPORT_SYMBOL(tty_port_free_xmit_buf);
2125 static char ptychar[] = "pqrstuvwxyzabcde";
2128 * pty_line_name - generate name for a pty
2129 * @driver: the tty driver in use
2130 * @index: the minor number
2131 * @p: output buffer of at least 6 bytes
2133 * Generate a name from a driver reference and write it to the output
2138 static void pty_line_name(struct tty_driver *driver, int index, char *p)
2140 int i = index + driver->name_base;
2141 /* ->name is initialized to "ttyp", but "tty" is expected */
2142 sprintf(p, "%s%c%x",
2143 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
2144 ptychar[i >> 4 & 0xf], i & 0xf);
2148 * pty_line_name - generate name for a tty
2149 * @driver: the tty driver in use
2150 * @index: the minor number
2151 * @p: output buffer of at least 7 bytes
2153 * Generate a name from a driver reference and write it to the output
2158 static void tty_line_name(struct tty_driver *driver, int index, char *p)
2160 sprintf(p, "%s%d", driver->name, index + driver->name_base);
2164 * init_dev - initialise a tty device
2165 * @driver: tty driver we are opening a device on
2166 * @idx: device index
2167 * @tty: returned tty structure
2169 * Prepare a tty device. This may not be a "new" clean device but
2170 * could also be an active device. The pty drivers require special
2171 * handling because of this.
2174 * The function is called under the tty_mutex, which
2175 * protects us from the tty struct or driver itself going away.
2177 * On exit the tty device has the line discipline attached and
2178 * a reference count of 1. If a pair was created for pty/tty use
2179 * and the other was a pty master then it too has a reference count of 1.
2181 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
2182 * failed open. The new code protects the open with a mutex, so it's
2183 * really quite straightforward. The mutex locking can probably be
2184 * relaxed for the (most common) case of reopening a tty.
2187 static int init_dev(struct tty_driver *driver, int idx,
2188 struct tty_struct **ret_tty)
2190 struct tty_struct *tty, *o_tty;
2191 struct ktermios *tp, **tp_loc, *o_tp, **o_tp_loc;
2192 struct ktermios *ltp, **ltp_loc, *o_ltp, **o_ltp_loc;
2194 struct tty_ldisc *ld;
2196 /* check whether we're reopening an existing tty */
2197 if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
2198 tty = devpts_get_tty(idx);
2200 * If we don't have a tty here on a slave open, it's because
2201 * the master already started the close process and there's
2202 * no relation between devpts file and tty anymore.
2204 if (!tty && driver->subtype == PTY_TYPE_SLAVE) {
2209 * It's safe from now on because init_dev() is called with
2210 * tty_mutex held and release_dev() won't change tty->count
2211 * or tty->flags without having to grab tty_mutex
2213 if (tty && driver->subtype == PTY_TYPE_MASTER)
2216 tty = driver->ttys[idx];
2218 if (tty) goto fast_track;
2221 * First time open is complex, especially for PTY devices.
2222 * This code guarantees that either everything succeeds and the
2223 * TTY is ready for operation, or else the table slots are vacated
2224 * and the allocated memory released. (Except that the termios
2225 * and locked termios may be retained.)
2228 if (!try_module_get(driver->owner)) {
2237 tty = alloc_tty_struct();
2240 initialize_tty_struct(tty);
2241 tty->driver = driver;
2242 tty->ops = driver->ops;
2244 tty_line_name(driver, idx, tty->name);
2246 if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
2247 tp_loc = &tty->termios;
2248 ltp_loc = &tty->termios_locked;
2250 tp_loc = &driver->termios[idx];
2251 ltp_loc = &driver->termios_locked[idx];
2255 tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
2258 *tp = driver->init_termios;
2262 ltp = kzalloc(sizeof(struct ktermios), GFP_KERNEL);
2267 if (driver->type == TTY_DRIVER_TYPE_PTY) {
2268 o_tty = alloc_tty_struct();
2271 initialize_tty_struct(o_tty);
2272 o_tty->driver = driver->other;
2273 o_tty->ops = driver->ops;
2275 tty_line_name(driver->other, idx, o_tty->name);
2277 if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
2278 o_tp_loc = &o_tty->termios;
2279 o_ltp_loc = &o_tty->termios_locked;
2281 o_tp_loc = &driver->other->termios[idx];
2282 o_ltp_loc = &driver->other->termios_locked[idx];
2286 o_tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
2289 *o_tp = driver->other->init_termios;
2293 o_ltp = kzalloc(sizeof(struct ktermios), GFP_KERNEL);
2299 * Everything allocated ... set up the o_tty structure.
2301 if (!(driver->other->flags & TTY_DRIVER_DEVPTS_MEM))
2302 driver->other->ttys[idx] = o_tty;
2307 o_tty->termios = *o_tp_loc;
2308 o_tty->termios_locked = *o_ltp_loc;
2309 driver->other->refcount++;
2310 if (driver->subtype == PTY_TYPE_MASTER)
2313 /* Establish the links in both directions */
2319 * All structures have been allocated, so now we install them.
2320 * Failures after this point use release_tty to clean up, so
2321 * there's no need to null out the local pointers.
2323 if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM))
2324 driver->ttys[idx] = tty;
2330 tty->termios = *tp_loc;
2331 tty->termios_locked = *ltp_loc;
2332 /* Compatibility until drivers always set this */
2333 tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
2334 tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
2339 * Structures all installed ... call the ldisc open routines.
2340 * If we fail here just call release_tty to clean up. No need
2341 * to decrement the use counts, as release_tty doesn't care.
2346 if (ld->ops->open) {
2347 retval = (ld->ops->open)(tty);
2349 goto release_mem_out;
2351 if (o_tty && o_tty->ldisc.ops->open) {
2352 retval = (o_tty->ldisc.ops->open)(o_tty);
2355 (ld->ops->close)(tty);
2356 goto release_mem_out;
2358 tty_ldisc_enable(o_tty);
2360 tty_ldisc_enable(tty);
2364 * This fast open can be used if the tty is already open.
2365 * No memory is allocated, and the only failures are from
2366 * attempting to open a closing tty or attempting multiple
2367 * opens on a pty master.
2370 if (test_bit(TTY_CLOSING, &tty->flags)) {
2374 if (driver->type == TTY_DRIVER_TYPE_PTY &&
2375 driver->subtype == PTY_TYPE_MASTER) {
2377 * special case for PTY masters: only one open permitted,
2378 * and the slave side open count is incremented as well.
2387 tty->driver = driver; /* N.B. why do this every time?? */
2390 if (!test_bit(TTY_LDISC, &tty->flags))
2391 printk(KERN_ERR "init_dev but no ldisc\n");
2395 /* All paths come through here to release the mutex */
2399 /* Release locally allocated memory ... nothing placed in slots */
2403 free_tty_struct(o_tty);
2406 free_tty_struct(tty);
2409 module_put(driver->owner);
2413 /* call the tty release_tty routine to clean out this slot */
2415 if (printk_ratelimit())
2416 printk(KERN_INFO "init_dev: ldisc open failed, "
2417 "clearing slot %d\n", idx);
2418 release_tty(tty, idx);
2423 * release_one_tty - release tty structure memory
2425 * Releases memory associated with a tty structure, and clears out the
2426 * driver table slots. This function is called when a device is no longer
2427 * in use. It also gets called when setup of a device fails.
2430 * tty_mutex - sometimes only
2431 * takes the file list lock internally when working on the list
2432 * of ttys that the driver keeps.
2433 * FIXME: should we require tty_mutex is held here ??
2435 static void release_one_tty(struct tty_struct *tty, int idx)
2437 int devpts = tty->driver->flags & TTY_DRIVER_DEVPTS_MEM;
2438 struct ktermios *tp;
2441 tty->driver->ttys[idx] = NULL;
2443 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
2446 tty->driver->termios[idx] = NULL;
2449 tp = tty->termios_locked;
2451 tty->driver->termios_locked[idx] = NULL;
2457 tty->driver->refcount--;
2460 list_del_init(&tty->tty_files);
2463 free_tty_struct(tty);
2467 * release_tty - release tty structure memory
2469 * Release both @tty and a possible linked partner (think pty pair),
2470 * and decrement the refcount of the backing module.
2473 * tty_mutex - sometimes only
2474 * takes the file list lock internally when working on the list
2475 * of ttys that the driver keeps.
2476 * FIXME: should we require tty_mutex is held here ??
2478 static void release_tty(struct tty_struct *tty, int idx)
2480 struct tty_driver *driver = tty->driver;
2483 release_one_tty(tty->link, idx);
2484 release_one_tty(tty, idx);
2485 module_put(driver->owner);
2489 * Even releasing the tty structures is a tricky business.. We have
2490 * to be very careful that the structures are all released at the
2491 * same time, as interrupts might otherwise get the wrong pointers.
2493 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
2494 * lead to double frees or releasing memory still in use.
2496 static void release_dev(struct file *filp)
2498 struct tty_struct *tty, *o_tty;
2499 struct tty_ldisc ld;
2500 int pty_master, tty_closing, o_tty_closing, do_sleep;
2504 unsigned long flags;
2506 tty = (struct tty_struct *)filp->private_data;
2507 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode,
2511 check_tty_count(tty, "release_dev");
2513 tty_fasync(-1, filp, 0);
2516 pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2517 tty->driver->subtype == PTY_TYPE_MASTER);
2518 devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0;
2521 #ifdef TTY_PARANOIA_CHECK
2522 if (idx < 0 || idx >= tty->driver->num) {
2523 printk(KERN_DEBUG "release_dev: bad idx when trying to "
2524 "free (%s)\n", tty->name);
2527 if (!(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
2528 if (tty != tty->driver->ttys[idx]) {
2529 printk(KERN_DEBUG "release_dev: driver.table[%d] not tty "
2530 "for (%s)\n", idx, tty->name);
2533 if (tty->termios != tty->driver->termios[idx]) {
2534 printk(KERN_DEBUG "release_dev: driver.termios[%d] not termios "
2539 if (tty->termios_locked != tty->driver->termios_locked[idx]) {
2540 printk(KERN_DEBUG "release_dev: driver.termios_locked[%d] not "
2541 "termios_locked for (%s)\n",
2548 #ifdef TTY_DEBUG_HANGUP
2549 printk(KERN_DEBUG "release_dev of %s (tty count=%d)...",
2550 tty_name(tty, buf), tty->count);
2553 #ifdef TTY_PARANOIA_CHECK
2554 if (tty->driver->other &&
2555 !(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
2556 if (o_tty != tty->driver->other->ttys[idx]) {
2557 printk(KERN_DEBUG "release_dev: other->table[%d] "
2558 "not o_tty for (%s)\n",
2562 if (o_tty->termios != tty->driver->other->termios[idx]) {
2563 printk(KERN_DEBUG "release_dev: other->termios[%d] "
2564 "not o_termios for (%s)\n",
2568 if (o_tty->termios_locked !=
2569 tty->driver->other->termios_locked[idx]) {
2570 printk(KERN_DEBUG "release_dev: other->termios_locked["
2571 "%d] not o_termios_locked for (%s)\n",
2575 if (o_tty->link != tty) {
2576 printk(KERN_DEBUG "release_dev: bad pty pointers\n");
2581 if (tty->ops->close)
2582 tty->ops->close(tty, filp);
2585 * Sanity check: if tty->count is going to zero, there shouldn't be
2586 * any waiters on tty->read_wait or tty->write_wait. We test the
2587 * wait queues and kick everyone out _before_ actually starting to
2588 * close. This ensures that we won't block while releasing the tty
2591 * The test for the o_tty closing is necessary, since the master and
2592 * slave sides may close in any order. If the slave side closes out
2593 * first, its count will be one, since the master side holds an open.
2594 * Thus this test wouldn't be triggered at the time the slave closes,
2597 * Note that it's possible for the tty to be opened again while we're
2598 * flushing out waiters. By recalculating the closing flags before
2599 * each iteration we avoid any problems.
2602 /* Guard against races with tty->count changes elsewhere and
2603 opens on /dev/tty */
2605 mutex_lock(&tty_mutex);
2606 tty_closing = tty->count <= 1;
2607 o_tty_closing = o_tty &&
2608 (o_tty->count <= (pty_master ? 1 : 0));
2612 if (waitqueue_active(&tty->read_wait)) {
2613 wake_up(&tty->read_wait);
2616 if (waitqueue_active(&tty->write_wait)) {
2617 wake_up(&tty->write_wait);
2621 if (o_tty_closing) {
2622 if (waitqueue_active(&o_tty->read_wait)) {
2623 wake_up(&o_tty->read_wait);
2626 if (waitqueue_active(&o_tty->write_wait)) {
2627 wake_up(&o_tty->write_wait);
2634 printk(KERN_WARNING "release_dev: %s: read/write wait queue "
2635 "active!\n", tty_name(tty, buf));
2636 mutex_unlock(&tty_mutex);
2641 * The closing flags are now consistent with the open counts on
2642 * both sides, and we've completed the last operation that could
2643 * block, so it's safe to proceed with closing.
2646 if (--o_tty->count < 0) {
2647 printk(KERN_WARNING "release_dev: bad pty slave count "
2649 o_tty->count, tty_name(o_tty, buf));
2653 if (--tty->count < 0) {
2654 printk(KERN_WARNING "release_dev: bad tty->count (%d) for %s\n",
2655 tty->count, tty_name(tty, buf));
2660 * We've decremented tty->count, so we need to remove this file
2661 * descriptor off the tty->tty_files list; this serves two
2663 * - check_tty_count sees the correct number of file descriptors
2664 * associated with this tty.
2665 * - do_tty_hangup no longer sees this file descriptor as
2666 * something that needs to be handled for hangups.
2669 filp->private_data = NULL;
2672 * Perform some housekeeping before deciding whether to return.
2674 * Set the TTY_CLOSING flag if this was the last open. In the
2675 * case of a pty we may have to wait around for the other side
2676 * to close, and TTY_CLOSING makes sure we can't be reopened.
2679 set_bit(TTY_CLOSING, &tty->flags);
2681 set_bit(TTY_CLOSING, &o_tty->flags);
2684 * If _either_ side is closing, make sure there aren't any
2685 * processes that still think tty or o_tty is their controlling
2688 if (tty_closing || o_tty_closing) {
2689 read_lock(&tasklist_lock);
2690 session_clear_tty(tty->session);
2692 session_clear_tty(o_tty->session);
2693 read_unlock(&tasklist_lock);
2696 mutex_unlock(&tty_mutex);
2698 /* check whether both sides are closing ... */
2699 if (!tty_closing || (o_tty && !o_tty_closing))
2702 #ifdef TTY_DEBUG_HANGUP
2703 printk(KERN_DEBUG "freeing tty structure...");
2706 * Prevent flush_to_ldisc() from rescheduling the work for later. Then
2707 * kill any delayed work. As this is the final close it does not
2708 * race with the set_ldisc code path.
2710 clear_bit(TTY_LDISC, &tty->flags);
2711 cancel_delayed_work(&tty->buf.work);
2714 * Wait for ->hangup_work and ->buf.work handlers to terminate
2717 flush_scheduled_work();
2720 * Wait for any short term users (we know they are just driver
2721 * side waiters as the file is closing so user count on the file
2724 spin_lock_irqsave(&tty_ldisc_lock, flags);
2725 while (tty->ldisc.refcount) {
2726 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
2727 wait_event(tty_ldisc_wait, tty->ldisc.refcount == 0);
2728 spin_lock_irqsave(&tty_ldisc_lock, flags);
2730 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
2732 * Shutdown the current line discipline, and reset it to N_TTY.
2734 * FIXME: this MUST get fixed for the new reflocking
2736 if (tty->ldisc.ops->close)
2737 (tty->ldisc.ops->close)(tty);
2738 tty_ldisc_put(tty->ldisc.ops);
2741 * Switch the line discipline back
2743 WARN_ON(tty_ldisc_get(N_TTY, &ld));
2744 tty_ldisc_assign(tty, &ld);
2745 tty_set_termios_ldisc(tty, N_TTY);
2747 /* FIXME: could o_tty be in setldisc here ? */
2748 clear_bit(TTY_LDISC, &o_tty->flags);
2749 if (o_tty->ldisc.ops->close)
2750 (o_tty->ldisc.ops->close)(o_tty);
2751 tty_ldisc_put(o_tty->ldisc.ops);
2752 WARN_ON(tty_ldisc_get(N_TTY, &ld));
2753 tty_ldisc_assign(o_tty, &ld);
2754 tty_set_termios_ldisc(o_tty, N_TTY);
2757 * The release_tty function takes care of the details of clearing
2758 * the slots and preserving the termios structure.
2760 release_tty(tty, idx);
2762 /* Make this pty number available for reallocation */
2764 devpts_kill_index(idx);
2768 * tty_open - open a tty device
2769 * @inode: inode of device file
2770 * @filp: file pointer to tty
2772 * tty_open and tty_release keep up the tty count that contains the
2773 * number of opens done on a tty. We cannot use the inode-count, as
2774 * different inodes might point to the same tty.
2776 * Open-counting is needed for pty masters, as well as for keeping
2777 * track of serial lines: DTR is dropped when the last close happens.
2778 * (This is not done solely through tty->count, now. - Ted 1/27/92)
2780 * The termios state of a pty is reset on first open so that
2781 * settings don't persist across reuse.
2783 * Locking: tty_mutex protects tty, get_tty_driver and init_dev work.
2784 * tty->count should protect the rest.
2785 * ->siglock protects ->signal/->sighand
2788 static int __tty_open(struct inode *inode, struct file *filp)
2790 struct tty_struct *tty;
2792 struct tty_driver *driver;
2794 dev_t device = inode->i_rdev;
2795 unsigned short saved_flags = filp->f_flags;
2797 nonseekable_open(inode, filp);
2800 noctty = filp->f_flags & O_NOCTTY;
2804 mutex_lock(&tty_mutex);
2806 if (device == MKDEV(TTYAUX_MAJOR, 0)) {
2807 tty = get_current_tty();
2809 mutex_unlock(&tty_mutex);
2812 driver = tty->driver;
2814 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
2819 if (device == MKDEV(TTY_MAJOR, 0)) {
2820 extern struct tty_driver *console_driver;
2821 driver = console_driver;
2827 if (device == MKDEV(TTYAUX_MAJOR, 1)) {
2828 driver = console_device(&index);
2830 /* Don't let /dev/console block */
2831 filp->f_flags |= O_NONBLOCK;
2835 mutex_unlock(&tty_mutex);
2839 driver = get_tty_driver(device, &index);
2841 mutex_unlock(&tty_mutex);
2845 retval = init_dev(driver, index, &tty);
2846 mutex_unlock(&tty_mutex);
2850 filp->private_data = tty;
2851 file_move(filp, &tty->tty_files);
2852 check_tty_count(tty, "tty_open");
2853 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2854 tty->driver->subtype == PTY_TYPE_MASTER)
2856 #ifdef TTY_DEBUG_HANGUP
2857 printk(KERN_DEBUG "opening %s...", tty->name);
2861 retval = tty->ops->open(tty, filp);
2865 filp->f_flags = saved_flags;
2867 if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) &&
2868 !capable(CAP_SYS_ADMIN))
2872 #ifdef TTY_DEBUG_HANGUP
2873 printk(KERN_DEBUG "error %d in opening %s...", retval,
2877 if (retval != -ERESTARTSYS)
2879 if (signal_pending(current))
2883 * Need to reset f_op in case a hangup happened.
2885 if (filp->f_op == &hung_up_tty_fops)
2886 filp->f_op = &tty_fops;
2890 mutex_lock(&tty_mutex);
2891 spin_lock_irq(¤t->sighand->siglock);
2893 current->signal->leader &&
2894 !current->signal->tty &&
2895 tty->session == NULL)
2896 __proc_set_tty(current, tty);
2897 spin_unlock_irq(¤t->sighand->siglock);
2898 mutex_unlock(&tty_mutex);
2902 /* BKL pushdown: scary code avoidance wrapper */
2903 static int tty_open(struct inode *inode, struct file *filp)
2908 ret = __tty_open(inode, filp);
2915 #ifdef CONFIG_UNIX98_PTYS
2917 * ptmx_open - open a unix 98 pty master
2918 * @inode: inode of device file
2919 * @filp: file pointer to tty
2921 * Allocate a unix98 pty master device from the ptmx driver.
2923 * Locking: tty_mutex protects theinit_dev work. tty->count should
2925 * allocated_ptys_lock handles the list of free pty numbers
2928 static int __ptmx_open(struct inode *inode, struct file *filp)
2930 struct tty_struct *tty;
2934 nonseekable_open(inode, filp);
2936 /* find a device that is not in use. */
2937 index = devpts_new_index();
2941 mutex_lock(&tty_mutex);
2942 retval = init_dev(ptm_driver, index, &tty);
2943 mutex_unlock(&tty_mutex);
2948 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
2949 filp->private_data = tty;
2950 file_move(filp, &tty->tty_files);
2952 retval = devpts_pty_new(tty->link);
2956 check_tty_count(tty, "ptmx_open");
2957 retval = ptm_driver->ops->open(tty, filp);
2964 devpts_kill_index(index);
2968 static int ptmx_open(struct inode *inode, struct file *filp)
2973 ret = __ptmx_open(inode, filp);
2980 * tty_release - vfs callback for close
2981 * @inode: inode of tty
2982 * @filp: file pointer for handle to tty
2984 * Called the last time each file handle is closed that references
2985 * this tty. There may however be several such references.
2988 * Takes bkl. See release_dev
2991 static int tty_release(struct inode *inode, struct file *filp)
3000 * tty_poll - check tty status
3001 * @filp: file being polled
3002 * @wait: poll wait structures to update
3004 * Call the line discipline polling method to obtain the poll
3005 * status of the device.
3007 * Locking: locks called line discipline but ldisc poll method
3008 * may be re-entered freely by other callers.
3011 static unsigned int tty_poll(struct file *filp, poll_table *wait)
3013 struct tty_struct *tty;
3014 struct tty_ldisc *ld;
3017 tty = (struct tty_struct *)filp->private_data;
3018 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_poll"))
3021 ld = tty_ldisc_ref_wait(tty);
3023 ret = (ld->ops->poll)(tty, filp, wait);
3024 tty_ldisc_deref(ld);
3028 static int tty_fasync(int fd, struct file *filp, int on)
3030 struct tty_struct *tty;
3031 unsigned long flags;
3035 tty = (struct tty_struct *)filp->private_data;
3036 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_fasync"))
3039 retval = fasync_helper(fd, filp, on, &tty->fasync);
3046 if (!waitqueue_active(&tty->read_wait))
3047 tty->minimum_to_wake = 1;
3048 spin_lock_irqsave(&tty->ctrl_lock, flags);
3051 type = PIDTYPE_PGID;
3053 pid = task_pid(current);
3056 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
3057 retval = __f_setown(filp, pid, type, 0);
3061 if (!tty->fasync && !waitqueue_active(&tty->read_wait))
3062 tty->minimum_to_wake = N_TTY_BUF_SIZE;
3071 * tiocsti - fake input character
3072 * @tty: tty to fake input into
3073 * @p: pointer to character
3075 * Fake input to a tty device. Does the necessary locking and
3078 * FIXME: does not honour flow control ??
3081 * Called functions take tty_ldisc_lock
3082 * current->signal->tty check is safe without locks
3084 * FIXME: may race normal receive processing
3087 static int tiocsti(struct tty_struct *tty, char __user *p)
3090 struct tty_ldisc *ld;
3092 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
3094 if (get_user(ch, p))
3096 ld = tty_ldisc_ref_wait(tty);
3097 ld->ops->receive_buf(tty, &ch, &mbz, 1);
3098 tty_ldisc_deref(ld);
3103 * tiocgwinsz - implement window query ioctl
3105 * @arg: user buffer for result
3107 * Copies the kernel idea of the window size into the user buffer.
3109 * Locking: tty->termios_mutex is taken to ensure the winsize data
3113 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
3117 mutex_lock(&tty->termios_mutex);
3118 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
3119 mutex_unlock(&tty->termios_mutex);
3121 return err ? -EFAULT: 0;
3125 * tiocswinsz - implement window size set ioctl
3127 * @arg: user buffer for result
3129 * Copies the user idea of the window size to the kernel. Traditionally
3130 * this is just advisory information but for the Linux console it
3131 * actually has driver level meaning and triggers a VC resize.
3134 * Called function use the console_sem is used to ensure we do
3135 * not try and resize the console twice at once.
3136 * The tty->termios_mutex is used to ensure we don't double
3137 * resize and get confused. Lock order - tty->termios_mutex before
3141 static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty,
3142 struct winsize __user *arg)
3144 struct winsize tmp_ws;
3145 struct pid *pgrp, *rpgrp;
3146 unsigned long flags;
3148 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
3151 mutex_lock(&tty->termios_mutex);
3152 if (!memcmp(&tmp_ws, &tty->winsize, sizeof(*arg)))
3156 if (tty->driver->type == TTY_DRIVER_TYPE_CONSOLE) {
3157 if (vc_lock_resize(tty->driver_data, tmp_ws.ws_col,
3159 mutex_unlock(&tty->termios_mutex);
3164 /* Get the PID values and reference them so we can
3165 avoid holding the tty ctrl lock while sending signals */
3166 spin_lock_irqsave(&tty->ctrl_lock, flags);
3167 pgrp = get_pid(tty->pgrp);
3168 rpgrp = get_pid(real_tty->pgrp);
3169 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
3172 kill_pgrp(pgrp, SIGWINCH, 1);
3173 if (rpgrp != pgrp && rpgrp)
3174 kill_pgrp(rpgrp, SIGWINCH, 1);
3179 tty->winsize = tmp_ws;
3180 real_tty->winsize = tmp_ws;
3182 mutex_unlock(&tty->termios_mutex);
3187 * tioccons - allow admin to move logical console
3188 * @file: the file to become console
3190 * Allow the adminstrator to move the redirected console device
3192 * Locking: uses redirect_lock to guard the redirect information
3195 static int tioccons(struct file *file)
3197 if (!capable(CAP_SYS_ADMIN))
3199 if (file->f_op->write == redirected_tty_write) {
3201 spin_lock(&redirect_lock);
3204 spin_unlock(&redirect_lock);
3209 spin_lock(&redirect_lock);
3211 spin_unlock(&redirect_lock);
3216 spin_unlock(&redirect_lock);
3221 * fionbio - non blocking ioctl
3222 * @file: file to set blocking value
3223 * @p: user parameter
3225 * Historical tty interfaces had a blocking control ioctl before
3226 * the generic functionality existed. This piece of history is preserved
3227 * in the expected tty API of posix OS's.
3229 * Locking: none, the open fle handle ensures it won't go away.
3232 static int fionbio(struct file *file, int __user *p)
3236 if (get_user(nonblock, p))
3239 /* file->f_flags is still BKL protected in the fs layer - vomit */
3242 file->f_flags |= O_NONBLOCK;
3244 file->f_flags &= ~O_NONBLOCK;
3250 * tiocsctty - set controlling tty
3251 * @tty: tty structure
3252 * @arg: user argument
3254 * This ioctl is used to manage job control. It permits a session
3255 * leader to set this tty as the controlling tty for the session.
3258 * Takes tty_mutex() to protect tty instance
3259 * Takes tasklist_lock internally to walk sessions
3260 * Takes ->siglock() when updating signal->tty
3263 static int tiocsctty(struct tty_struct *tty, int arg)
3266 if (current->signal->leader && (task_session(current) == tty->session))
3269 mutex_lock(&tty_mutex);
3271 * The process must be a session leader and
3272 * not have a controlling tty already.
3274 if (!current->signal->leader || current->signal->tty) {
3281 * This tty is already the controlling
3282 * tty for another session group!
3284 if (arg == 1 && capable(CAP_SYS_ADMIN)) {
3288 read_lock(&tasklist_lock);
3289 session_clear_tty(tty->session);
3290 read_unlock(&tasklist_lock);
3296 proc_set_tty(current, tty);
3298 mutex_unlock(&tty_mutex);
3303 * tty_get_pgrp - return a ref counted pgrp pid
3306 * Returns a refcounted instance of the pid struct for the process
3307 * group controlling the tty.
3310 struct pid *tty_get_pgrp(struct tty_struct *tty)
3312 unsigned long flags;
3315 spin_lock_irqsave(&tty->ctrl_lock, flags);
3316 pgrp = get_pid(tty->pgrp);
3317 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
3321 EXPORT_SYMBOL_GPL(tty_get_pgrp);
3324 * tiocgpgrp - get process group
3325 * @tty: tty passed by user
3326 * @real_tty: tty side of the tty pased by the user if a pty else the tty
3329 * Obtain the process group of the tty. If there is no process group
3332 * Locking: none. Reference to current->signal->tty is safe.
3335 static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
3340 * (tty == real_tty) is a cheap way of
3341 * testing if the tty is NOT a master pty.
3343 if (tty == real_tty && current->signal->tty != real_tty)
3345 pid = tty_get_pgrp(real_tty);
3346 ret = put_user(pid_vnr(pid), p);
3352 * tiocspgrp - attempt to set process group
3353 * @tty: tty passed by user
3354 * @real_tty: tty side device matching tty passed by user
3357 * Set the process group of the tty to the session passed. Only
3358 * permitted where the tty session is our session.
3360 * Locking: RCU, ctrl lock
3363 static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
3367 int retval = tty_check_change(real_tty);
3368 unsigned long flags;
3374 if (!current->signal->tty ||
3375 (current->signal->tty != real_tty) ||
3376 (real_tty->session != task_session(current)))
3378 if (get_user(pgrp_nr, p))
3383 pgrp = find_vpid(pgrp_nr);
3388 if (session_of_pgrp(pgrp) != task_session(current))
3391 spin_lock_irqsave(&tty->ctrl_lock, flags);
3392 put_pid(real_tty->pgrp);
3393 real_tty->pgrp = get_pid(pgrp);
3394 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
3401 * tiocgsid - get session id
3402 * @tty: tty passed by user
3403 * @real_tty: tty side of the tty pased by the user if a pty else the tty
3404 * @p: pointer to returned session id
3406 * Obtain the session id of the tty. If there is no session
3409 * Locking: none. Reference to current->signal->tty is safe.
3412 static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
3415 * (tty == real_tty) is a cheap way of
3416 * testing if the tty is NOT a master pty.
3418 if (tty == real_tty && current->signal->tty != real_tty)
3420 if (!real_tty->session)
3422 return put_user(pid_vnr(real_tty->session), p);
3426 * tiocsetd - set line discipline
3428 * @p: pointer to user data
3430 * Set the line discipline according to user request.
3432 * Locking: see tty_set_ldisc, this function is just a helper
3435 static int tiocsetd(struct tty_struct *tty, int __user *p)
3440 if (get_user(ldisc, p))
3444 ret = tty_set_ldisc(tty, ldisc);
3451 * send_break - performed time break
3452 * @tty: device to break on
3453 * @duration: timeout in mS
3455 * Perform a timed break on hardware that lacks its own driver level
3456 * timed break functionality.
3459 * atomic_write_lock serializes
3463 static int send_break(struct tty_struct *tty, unsigned int duration)
3465 if (tty_write_lock(tty, 0) < 0)
3467 tty->ops->break_ctl(tty, -1);
3468 if (!signal_pending(current))
3469 msleep_interruptible(duration);
3470 tty->ops->break_ctl(tty, 0);
3471 tty_write_unlock(tty);
3472 if (signal_pending(current))
3478 * tty_tiocmget - get modem status
3480 * @file: user file pointer
3481 * @p: pointer to result
3483 * Obtain the modem status bits from the tty driver if the feature
3484 * is supported. Return -EINVAL if it is not available.
3486 * Locking: none (up to the driver)
3489 static int tty_tiocmget(struct tty_struct *tty, struct file *file, int __user *p)
3491 int retval = -EINVAL;
3493 if (tty->ops->tiocmget) {
3494 retval = tty->ops->tiocmget(tty, file);
3497 retval = put_user(retval, p);
3503 * tty_tiocmset - set modem status
3505 * @file: user file pointer
3506 * @cmd: command - clear bits, set bits or set all
3507 * @p: pointer to desired bits
3509 * Set the modem status bits from the tty driver if the feature
3510 * is supported. Return -EINVAL if it is not available.
3512 * Locking: none (up to the driver)
3515 static int tty_tiocmset(struct tty_struct *tty, struct file *file, unsigned int cmd,
3519 unsigned int set, clear, val;
3521 if (tty->ops->tiocmset == NULL)
3524 retval = get_user(val, p);
3540 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
3541 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
3542 return tty->ops->tiocmset(tty, file, set, clear);
3546 * Split this up, as gcc can choke on it otherwise..
3548 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
3550 struct tty_struct *tty, *real_tty;
3551 void __user *p = (void __user *)arg;
3553 struct tty_ldisc *ld;
3554 struct inode *inode = file->f_dentry->d_inode;
3556 tty = (struct tty_struct *)file->private_data;
3557 if (tty_paranoia_check(tty, inode, "tty_ioctl"))
3561 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
3562 tty->driver->subtype == PTY_TYPE_MASTER)
3563 real_tty = tty->link;
3566 * Break handling by driver
3571 if (!tty->ops->break_ctl) {
3575 if (tty->ops->ioctl)
3576 retval = tty->ops->ioctl(tty, file, cmd, arg);
3577 if (retval != -EINVAL && retval != -ENOIOCTLCMD)
3578 printk(KERN_WARNING "tty: driver %s needs updating to use break_ctl\n", tty->driver->name);
3581 /* These two ioctl's always return success; even if */
3582 /* the driver doesn't support them. */
3585 if (!tty->ops->ioctl)
3587 retval = tty->ops->ioctl(tty, file, cmd, arg);
3588 if (retval != -EINVAL && retval != -ENOIOCTLCMD)
3589 printk(KERN_WARNING "tty: driver %s needs updating to use break_ctl\n", tty->driver->name);
3590 if (retval == -ENOIOCTLCMD)
3597 * Factor out some common prep work
3605 retval = tty_check_change(tty);
3608 if (cmd != TIOCCBRK) {
3609 tty_wait_until_sent(tty, 0);
3610 if (signal_pending(current))
3618 return tiocsti(tty, p);
3620 return tiocgwinsz(tty, p);
3622 return tiocswinsz(tty, real_tty, p);
3624 return real_tty != tty ? -EINVAL : tioccons(file);
3626 return fionbio(file, p);
3628 set_bit(TTY_EXCLUSIVE, &tty->flags);
3631 clear_bit(TTY_EXCLUSIVE, &tty->flags);
3634 if (current->signal->tty != tty)
3639 return tiocsctty(tty, arg);
3641 return tiocgpgrp(tty, real_tty, p);
3643 return tiocspgrp(tty, real_tty, p);
3645 return tiocgsid(tty, real_tty, p);
3647 return put_user(tty->ldisc.ops->num, (int __user *)p);
3649 return tiocsetd(tty, p);
3652 return tioclinux(tty, arg);
3657 case TIOCSBRK: /* Turn break on, unconditionally */
3658 if (tty->ops->break_ctl)
3659 tty->ops->break_ctl(tty, -1);
3662 case TIOCCBRK: /* Turn break off, unconditionally */
3663 if (tty->ops->break_ctl)
3664 tty->ops->break_ctl(tty, 0);
3666 case TCSBRK: /* SVID version: non-zero arg --> no break */
3667 /* non-zero arg means wait for all output data
3668 * to be sent (performed above) but don't send break.
3669 * This is used by the tcdrain() termios function.
3672 return send_break(tty, 250);
3674 case TCSBRKP: /* support for POSIX tcsendbreak() */
3675 return send_break(tty, arg ? arg*100 : 250);
3678 return tty_tiocmget(tty, file, p);
3682 return tty_tiocmset(tty, file, cmd, p);
3687 /* flush tty buffer and allow ldisc to process ioctl */
3688 tty_buffer_flush(tty);
3693 if (tty->ops->ioctl) {
3694 retval = (tty->ops->ioctl)(tty, file, cmd, arg);
3695 if (retval != -ENOIOCTLCMD)
3698 ld = tty_ldisc_ref_wait(tty);
3700 if (ld->ops->ioctl) {
3701 retval = ld->ops->ioctl(tty, file, cmd, arg);
3702 if (retval == -ENOIOCTLCMD)
3705 tty_ldisc_deref(ld);
3709 #ifdef CONFIG_COMPAT
3710 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
3713 struct inode *inode = file->f_dentry->d_inode;
3714 struct tty_struct *tty = file->private_data;
3715 struct tty_ldisc *ld;
3716 int retval = -ENOIOCTLCMD;
3718 if (tty_paranoia_check(tty, inode, "tty_ioctl"))
3721 if (tty->ops->compat_ioctl) {
3722 retval = (tty->ops->compat_ioctl)(tty, file, cmd, arg);
3723 if (retval != -ENOIOCTLCMD)
3727 ld = tty_ldisc_ref_wait(tty);
3728 if (ld->ops->compat_ioctl)
3729 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
3730 tty_ldisc_deref(ld);
3737 * This implements the "Secure Attention Key" --- the idea is to
3738 * prevent trojan horses by killing all processes associated with this
3739 * tty when the user hits the "Secure Attention Key". Required for
3740 * super-paranoid applications --- see the Orange Book for more details.
3742 * This code could be nicer; ideally it should send a HUP, wait a few
3743 * seconds, then send a INT, and then a KILL signal. But you then
3744 * have to coordinate with the init process, since all processes associated
3745 * with the current tty must be dead before the new getty is allowed
3748 * Now, if it would be correct ;-/ The current code has a nasty hole -
3749 * it doesn't catch files in flight. We may send the descriptor to ourselves
3750 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
3752 * Nasty bug: do_SAK is being called in interrupt context. This can
3753 * deadlock. We punt it up to process context. AKPM - 16Mar2001
3755 void __do_SAK(struct tty_struct *tty)
3760 struct task_struct *g, *p;
3761 struct pid *session;
3764 struct fdtable *fdt;
3768 session = tty->session;
3770 tty_ldisc_flush(tty);
3772 tty_driver_flush_buffer(tty);
3774 read_lock(&tasklist_lock);
3775 /* Kill the entire session */
3776 do_each_pid_task(session, PIDTYPE_SID, p) {
3777 printk(KERN_NOTICE "SAK: killed process %d"
3778 " (%s): task_session_nr(p)==tty->session\n",
3779 task_pid_nr(p), p->comm);
3780 send_sig(SIGKILL, p, 1);
3781 } while_each_pid_task(session, PIDTYPE_SID, p);
3782 /* Now kill any processes that happen to have the
3785 do_each_thread(g, p) {
3786 if (p->signal->tty == tty) {
3787 printk(KERN_NOTICE "SAK: killed process %d"
3788 " (%s): task_session_nr(p)==tty->session\n",
3789 task_pid_nr(p), p->comm);
3790 send_sig(SIGKILL, p, 1);
3796 * We don't take a ref to the file, so we must
3797 * hold ->file_lock instead.
3799 spin_lock(&p->files->file_lock);
3800 fdt = files_fdtable(p->files);
3801 for (i = 0; i < fdt->max_fds; i++) {
3802 filp = fcheck_files(p->files, i);
3805 if (filp->f_op->read == tty_read &&
3806 filp->private_data == tty) {
3807 printk(KERN_NOTICE "SAK: killed process %d"
3808 " (%s): fd#%d opened to the tty\n",
3809 task_pid_nr(p), p->comm, i);
3810 force_sig(SIGKILL, p);
3814 spin_unlock(&p->files->file_lock);
3817 } while_each_thread(g, p);
3818 read_unlock(&tasklist_lock);
3822 static void do_SAK_work(struct work_struct *work)
3824 struct tty_struct *tty =
3825 container_of(work, struct tty_struct, SAK_work);
3830 * The tq handling here is a little racy - tty->SAK_work may already be queued.
3831 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
3832 * the values which we write to it will be identical to the values which it
3833 * already has. --akpm
3835 void do_SAK(struct tty_struct *tty)
3839 schedule_work(&tty->SAK_work);
3842 EXPORT_SYMBOL(do_SAK);
3846 * @work: tty structure passed from work queue.
3848 * This routine is called out of the software interrupt to flush data
3849 * from the buffer chain to the line discipline.
3851 * Locking: holds tty->buf.lock to guard buffer list. Drops the lock
3852 * while invoking the line discipline receive_buf method. The
3853 * receive_buf method is single threaded for each tty instance.
3856 static void flush_to_ldisc(struct work_struct *work)
3858 struct tty_struct *tty =
3859 container_of(work, struct tty_struct, buf.work.work);
3860 unsigned long flags;
3861 struct tty_ldisc *disc;
3862 struct tty_buffer *tbuf, *head;
3864 unsigned char *flag_buf;
3866 disc = tty_ldisc_ref(tty);
3867 if (disc == NULL) /* !TTY_LDISC */
3870 spin_lock_irqsave(&tty->buf.lock, flags);
3871 /* So we know a flush is running */
3872 set_bit(TTY_FLUSHING, &tty->flags);
3873 head = tty->buf.head;
3875 tty->buf.head = NULL;
3877 int count = head->commit - head->read;
3879 if (head->next == NULL)
3883 tty_buffer_free(tty, tbuf);
3886 /* Ldisc or user is trying to flush the buffers
3887 we are feeding to the ldisc, stop feeding the
3888 line discipline as we want to empty the queue */
3889 if (test_bit(TTY_FLUSHPENDING, &tty->flags))
3891 if (!tty->receive_room) {
3892 schedule_delayed_work(&tty->buf.work, 1);
3895 if (count > tty->receive_room)
3896 count = tty->receive_room;
3897 char_buf = head->char_buf_ptr + head->read;
3898 flag_buf = head->flag_buf_ptr + head->read;
3899 head->read += count;
3900 spin_unlock_irqrestore(&tty->buf.lock, flags);
3901 disc->ops->receive_buf(tty, char_buf,
3903 spin_lock_irqsave(&tty->buf.lock, flags);
3905 /* Restore the queue head */
3906 tty->buf.head = head;
3908 /* We may have a deferred request to flush the input buffer,
3909 if so pull the chain under the lock and empty the queue */
3910 if (test_bit(TTY_FLUSHPENDING, &tty->flags)) {
3911 __tty_buffer_flush(tty);
3912 clear_bit(TTY_FLUSHPENDING, &tty->flags);
3913 wake_up(&tty->read_wait);
3915 clear_bit(TTY_FLUSHING, &tty->flags);
3916 spin_unlock_irqrestore(&tty->buf.lock, flags);
3918 tty_ldisc_deref(disc);
3922 * tty_flip_buffer_push - terminal
3925 * Queue a push of the terminal flip buffers to the line discipline. This
3926 * function must not be called from IRQ context if tty->low_latency is set.
3928 * In the event of the queue being busy for flipping the work will be
3929 * held off and retried later.
3931 * Locking: tty buffer lock. Driver locks in low latency mode.
3934 void tty_flip_buffer_push(struct tty_struct *tty)
3936 unsigned long flags;
3937 spin_lock_irqsave(&tty->buf.lock, flags);
3938 if (tty->buf.tail != NULL)
3939 tty->buf.tail->commit = tty->buf.tail->used;
3940 spin_unlock_irqrestore(&tty->buf.lock, flags);
3942 if (tty->low_latency)
3943 flush_to_ldisc(&tty->buf.work.work);
3945 schedule_delayed_work(&tty->buf.work, 1);
3948 EXPORT_SYMBOL(tty_flip_buffer_push);
3952 * initialize_tty_struct
3953 * @tty: tty to initialize
3955 * This subroutine initializes a tty structure that has been newly
3958 * Locking: none - tty in question must not be exposed at this point
3961 static void initialize_tty_struct(struct tty_struct *tty)
3963 struct tty_ldisc ld;
3964 memset(tty, 0, sizeof(struct tty_struct));
3965 tty->magic = TTY_MAGIC;
3966 if (tty_ldisc_get(N_TTY, &ld) < 0)
3967 panic("n_tty: init_tty");
3968 tty_ldisc_assign(tty, &ld);
3969 tty->session = NULL;
3971 tty->overrun_time = jiffies;
3972 tty->buf.head = tty->buf.tail = NULL;
3973 tty_buffer_init(tty);
3974 INIT_DELAYED_WORK(&tty->buf.work, flush_to_ldisc);
3975 mutex_init(&tty->termios_mutex);
3976 init_waitqueue_head(&tty->write_wait);
3977 init_waitqueue_head(&tty->read_wait);
3978 INIT_WORK(&tty->hangup_work, do_tty_hangup);
3979 mutex_init(&tty->atomic_read_lock);
3980 mutex_init(&tty->atomic_write_lock);
3981 spin_lock_init(&tty->read_lock);
3982 spin_lock_init(&tty->ctrl_lock);
3983 INIT_LIST_HEAD(&tty->tty_files);
3984 INIT_WORK(&tty->SAK_work, do_SAK_work);
3988 * tty_put_char - write one character to a tty
3992 * Write one byte to the tty using the provided put_char method
3993 * if present. Returns the number of characters successfully output.
3995 * Note: the specific put_char operation in the driver layer may go
3996 * away soon. Don't call it directly, use this method
3999 int tty_put_char(struct tty_struct *tty, unsigned char ch)
4001 if (tty->ops->put_char)
4002 return tty->ops->put_char(tty, ch);
4003 return tty->ops->write(tty, &ch, 1);
4006 EXPORT_SYMBOL_GPL(tty_put_char);
4008 static struct class *tty_class;
4011 * tty_register_device - register a tty device
4012 * @driver: the tty driver that describes the tty device
4013 * @index: the index in the tty driver for this tty device
4014 * @device: a struct device that is associated with this tty device.
4015 * This field is optional, if there is no known struct device
4016 * for this tty device it can be set to NULL safely.
4018 * Returns a pointer to the struct device for this tty device
4019 * (or ERR_PTR(-EFOO) on error).
4021 * This call is required to be made to register an individual tty device
4022 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
4023 * that bit is not set, this function should not be called by a tty
4029 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
4030 struct device *device)
4033 dev_t dev = MKDEV(driver->major, driver->minor_start) + index;
4035 if (index >= driver->num) {
4036 printk(KERN_ERR "Attempt to register invalid tty line number "
4038 return ERR_PTR(-EINVAL);
4041 if (driver->type == TTY_DRIVER_TYPE_PTY)
4042 pty_line_name(driver, index, name);
4044 tty_line_name(driver, index, name);
4046 return device_create(tty_class, device, dev, name);
4050 * tty_unregister_device - unregister a tty device
4051 * @driver: the tty driver that describes the tty device
4052 * @index: the index in the tty driver for this tty device
4054 * If a tty device is registered with a call to tty_register_device() then
4055 * this function must be called when the tty device is gone.
4060 void tty_unregister_device(struct tty_driver *driver, unsigned index)
4062 device_destroy(tty_class,
4063 MKDEV(driver->major, driver->minor_start) + index);
4066 EXPORT_SYMBOL(tty_register_device);
4067 EXPORT_SYMBOL(tty_unregister_device);
4069 struct tty_driver *alloc_tty_driver(int lines)
4071 struct tty_driver *driver;
4073 driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
4075 driver->magic = TTY_DRIVER_MAGIC;
4076 driver->num = lines;
4077 /* later we'll move allocation of tables here */
4082 void put_tty_driver(struct tty_driver *driver)
4087 void tty_set_operations(struct tty_driver *driver,
4088 const struct tty_operations *op)
4093 EXPORT_SYMBOL(alloc_tty_driver);
4094 EXPORT_SYMBOL(put_tty_driver);
4095 EXPORT_SYMBOL(tty_set_operations);
4098 * Called by a tty driver to register itself.
4100 int tty_register_driver(struct tty_driver *driver)
4107 if (driver->flags & TTY_DRIVER_INSTALLED)
4110 if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM) && driver->num) {
4111 p = kzalloc(driver->num * 3 * sizeof(void *), GFP_KERNEL);
4116 if (!driver->major) {
4117 error = alloc_chrdev_region(&dev, driver->minor_start,
4118 driver->num, driver->name);
4120 driver->major = MAJOR(dev);
4121 driver->minor_start = MINOR(dev);
4124 dev = MKDEV(driver->major, driver->minor_start);
4125 error = register_chrdev_region(dev, driver->num, driver->name);
4133 driver->ttys = (struct tty_struct **)p;
4134 driver->termios = (struct ktermios **)(p + driver->num);
4135 driver->termios_locked = (struct ktermios **)
4136 (p + driver->num * 2);
4138 driver->ttys = NULL;
4139 driver->termios = NULL;
4140 driver->termios_locked = NULL;
4143 cdev_init(&driver->cdev, &tty_fops);
4144 driver->cdev.owner = driver->owner;
4145 error = cdev_add(&driver->cdev, dev, driver->num);
4147 unregister_chrdev_region(dev, driver->num);
4148 driver->ttys = NULL;
4149 driver->termios = driver->termios_locked = NULL;
4154 mutex_lock(&tty_mutex);
4155 list_add(&driver->tty_drivers, &tty_drivers);
4156 mutex_unlock(&tty_mutex);
4158 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
4159 for (i = 0; i < driver->num; i++)
4160 tty_register_device(driver, i, NULL);
4162 proc_tty_register_driver(driver);
4166 EXPORT_SYMBOL(tty_register_driver);
4169 * Called by a tty driver to unregister itself.
4171 int tty_unregister_driver(struct tty_driver *driver)
4174 struct ktermios *tp;
4177 if (driver->refcount)
4180 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
4182 mutex_lock(&tty_mutex);
4183 list_del(&driver->tty_drivers);
4184 mutex_unlock(&tty_mutex);
4187 * Free the termios and termios_locked structures because
4188 * we don't want to get memory leaks when modular tty
4189 * drivers are removed from the kernel.
4191 for (i = 0; i < driver->num; i++) {
4192 tp = driver->termios[i];
4194 driver->termios[i] = NULL;
4197 tp = driver->termios_locked[i];
4199 driver->termios_locked[i] = NULL;
4202 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
4203 tty_unregister_device(driver, i);
4206 proc_tty_unregister_driver(driver);
4207 driver->ttys = NULL;
4208 driver->termios = driver->termios_locked = NULL;
4210 cdev_del(&driver->cdev);
4213 EXPORT_SYMBOL(tty_unregister_driver);
4215 dev_t tty_devnum(struct tty_struct *tty)
4217 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
4219 EXPORT_SYMBOL(tty_devnum);
4221 void proc_clear_tty(struct task_struct *p)
4223 spin_lock_irq(&p->sighand->siglock);
4224 p->signal->tty = NULL;
4225 spin_unlock_irq(&p->sighand->siglock);
4227 EXPORT_SYMBOL(proc_clear_tty);
4229 /* Called under the sighand lock */
4231 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
4234 unsigned long flags;
4235 /* We should not have a session or pgrp to put here but.... */
4236 spin_lock_irqsave(&tty->ctrl_lock, flags);
4237 put_pid(tty->session);
4239 tty->pgrp = get_pid(task_pgrp(tsk));
4240 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
4241 tty->session = get_pid(task_session(tsk));
4243 put_pid(tsk->signal->tty_old_pgrp);
4244 tsk->signal->tty = tty;
4245 tsk->signal->tty_old_pgrp = NULL;
4248 static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
4250 spin_lock_irq(&tsk->sighand->siglock);
4251 __proc_set_tty(tsk, tty);
4252 spin_unlock_irq(&tsk->sighand->siglock);
4255 struct tty_struct *get_current_tty(void)
4257 struct tty_struct *tty;
4258 WARN_ON_ONCE(!mutex_is_locked(&tty_mutex));
4259 tty = current->signal->tty;
4261 * session->tty can be changed/cleared from under us, make sure we
4262 * issue the load. The obtained pointer, when not NULL, is valid as
4263 * long as we hold tty_mutex.
4268 EXPORT_SYMBOL_GPL(get_current_tty);
4271 * Initialize the console device. This is called *early*, so
4272 * we can't necessarily depend on lots of kernel help here.
4273 * Just do some early initializations, and do the complex setup
4276 void __init console_init(void)
4280 /* Setup the default TTY line discipline. */
4281 (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY);
4284 * set up the console device so that later boot sequences can
4285 * inform about problems etc..
4287 call = __con_initcall_start;
4288 while (call < __con_initcall_end) {
4294 static int __init tty_class_init(void)
4296 tty_class = class_create(THIS_MODULE, "tty");
4297 if (IS_ERR(tty_class))
4298 return PTR_ERR(tty_class);
4302 postcore_initcall(tty_class_init);
4304 /* 3/2004 jmc: why do these devices exist? */
4306 static struct cdev tty_cdev, console_cdev;
4307 #ifdef CONFIG_UNIX98_PTYS
4308 static struct cdev ptmx_cdev;
4311 static struct cdev vc0_cdev;
4315 * Ok, now we can initialize the rest of the tty devices and can count
4316 * on memory allocations, interrupts etc..
4318 static int __init tty_init(void)
4320 cdev_init(&tty_cdev, &tty_fops);
4321 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
4322 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
4323 panic("Couldn't register /dev/tty driver\n");
4324 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), "tty");
4326 cdev_init(&console_cdev, &console_fops);
4327 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
4328 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
4329 panic("Couldn't register /dev/console driver\n");
4330 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 1), "console");
4332 #ifdef CONFIG_UNIX98_PTYS
4333 cdev_init(&ptmx_cdev, &ptmx_fops);
4334 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
4335 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
4336 panic("Couldn't register /dev/ptmx driver\n");
4337 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), "ptmx");
4341 cdev_init(&vc0_cdev, &console_fops);
4342 if (cdev_add(&vc0_cdev, MKDEV(TTY_MAJOR, 0), 1) ||
4343 register_chrdev_region(MKDEV(TTY_MAJOR, 0), 1, "/dev/vc/0") < 0)
4344 panic("Couldn't register /dev/tty0 driver\n");
4345 device_create(tty_class, NULL, MKDEV(TTY_MAJOR, 0), "tty0");
4351 module_init(tty_init);