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/console.h>
82 #include <linux/timer.h>
83 #include <linux/ctype.h>
86 #include <linux/string.h>
87 #include <linux/slab.h>
88 #include <linux/poll.h>
89 #include <linux/proc_fs.h>
90 #include <linux/init.h>
91 #include <linux/module.h>
92 #include <linux/smp_lock.h>
93 #include <linux/device.h>
94 #include <linux/idr.h>
95 #include <linux/wait.h>
96 #include <linux/bitops.h>
97 #include <linux/delay.h>
99 #include <asm/uaccess.h>
100 #include <asm/system.h>
102 #include <linux/kbd_kern.h>
103 #include <linux/vt_kern.h>
104 #include <linux/selection.h>
106 #include <linux/kmod.h>
107 #include <linux/nsproxy.h>
109 #undef TTY_DEBUG_HANGUP
111 #define TTY_PARANOIA_CHECK 1
112 #define CHECK_TTY_COUNT 1
114 struct ktermios tty_std_termios = { /* for the benefit of tty drivers */
115 .c_iflag = ICRNL | IXON,
116 .c_oflag = OPOST | ONLCR,
117 .c_cflag = B38400 | CS8 | CREAD | HUPCL,
118 .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
119 ECHOCTL | ECHOKE | IEXTEN,
125 EXPORT_SYMBOL(tty_std_termios);
127 /* This list gets poked at by procfs and various bits of boot up code. This
128 could do with some rationalisation such as pulling the tty proc function
131 LIST_HEAD(tty_drivers); /* linked list of tty drivers */
133 /* Mutex to protect creating and releasing a tty. This is shared with
134 vt.c for deeply disgusting hack reasons */
135 DEFINE_MUTEX(tty_mutex);
136 EXPORT_SYMBOL(tty_mutex);
138 #ifdef CONFIG_UNIX98_PTYS
139 extern struct tty_driver *ptm_driver; /* Unix98 pty masters; for /dev/ptmx */
140 extern int pty_limit; /* Config limit on Unix98 ptys */
141 static DEFINE_IDR(allocated_ptys);
142 static DEFINE_MUTEX(allocated_ptys_lock);
143 static int ptmx_open(struct inode *, struct file *);
146 static void initialize_tty_struct(struct tty_struct *tty);
148 static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
149 static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
150 ssize_t redirected_tty_write(struct file *, const char __user *,
152 static unsigned int tty_poll(struct file *, poll_table *);
153 static int tty_open(struct inode *, struct file *);
154 static int tty_release(struct inode *, struct file *);
155 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
157 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
160 #define tty_compat_ioctl NULL
162 static int tty_fasync(int fd, struct file *filp, int on);
163 static void release_tty(struct tty_struct *tty, int idx);
164 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
165 static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
168 * alloc_tty_struct - allocate a tty object
170 * Return a new empty tty structure. The data fields have not
171 * been initialized in any way but has been zeroed
176 static struct tty_struct *alloc_tty_struct(void)
178 return kzalloc(sizeof(struct tty_struct), GFP_KERNEL);
181 static void tty_buffer_free_all(struct tty_struct *);
184 * free_tty_struct - free a disused tty
185 * @tty: tty struct to free
187 * Free the write buffers, tty queue and tty memory itself.
189 * Locking: none. Must be called after tty is definitely unused
192 static inline void free_tty_struct(struct tty_struct *tty)
194 kfree(tty->write_buf);
195 tty_buffer_free_all(tty);
199 #define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base)
202 * tty_name - return tty naming
203 * @tty: tty structure
204 * @buf: buffer for output
206 * Convert a tty structure into a name. The name reflects the kernel
207 * naming policy and if udev is in use may not reflect user space
212 char *tty_name(struct tty_struct *tty, char *buf)
214 if (!tty) /* Hmm. NULL pointer. That's fun. */
215 strcpy(buf, "NULL tty");
217 strcpy(buf, tty->name);
221 EXPORT_SYMBOL(tty_name);
223 int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
226 #ifdef TTY_PARANOIA_CHECK
229 "null TTY for (%d:%d) in %s\n",
230 imajor(inode), iminor(inode), routine);
233 if (tty->magic != TTY_MAGIC) {
235 "bad magic number for tty struct (%d:%d) in %s\n",
236 imajor(inode), iminor(inode), routine);
243 static int check_tty_count(struct tty_struct *tty, const char *routine)
245 #ifdef CHECK_TTY_COUNT
250 list_for_each(p, &tty->tty_files) {
254 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
255 tty->driver->subtype == PTY_TYPE_SLAVE &&
256 tty->link && tty->link->count)
258 if (tty->count != count) {
259 printk(KERN_WARNING "Warning: dev (%s) tty->count(%d) "
260 "!= #fd's(%d) in %s\n",
261 tty->name, tty->count, count, routine);
269 * Tty buffer allocation management
273 * tty_buffer_free_all - free buffers used by a tty
274 * @tty: tty to free from
276 * Remove all the buffers pending on a tty whether queued with data
277 * or in the free ring. Must be called when the tty is no longer in use
282 static void tty_buffer_free_all(struct tty_struct *tty)
284 struct tty_buffer *thead;
285 while ((thead = tty->buf.head) != NULL) {
286 tty->buf.head = thead->next;
289 while ((thead = tty->buf.free) != NULL) {
290 tty->buf.free = thead->next;
293 tty->buf.tail = NULL;
294 tty->buf.memory_used = 0;
298 * tty_buffer_init - prepare a tty buffer structure
299 * @tty: tty to initialise
301 * Set up the initial state of the buffer management for a tty device.
302 * Must be called before the other tty buffer functions are used.
307 static void tty_buffer_init(struct tty_struct *tty)
309 spin_lock_init(&tty->buf.lock);
310 tty->buf.head = NULL;
311 tty->buf.tail = NULL;
312 tty->buf.free = NULL;
313 tty->buf.memory_used = 0;
317 * tty_buffer_alloc - allocate a tty buffer
319 * @size: desired size (characters)
321 * Allocate a new tty buffer to hold the desired number of characters.
322 * Return NULL if out of memory or the allocation would exceed the
325 * Locking: Caller must hold tty->buf.lock
328 static struct tty_buffer *tty_buffer_alloc(struct tty_struct *tty, size_t size)
330 struct tty_buffer *p;
332 if (tty->buf.memory_used + size > 65536)
334 p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC);
342 p->char_buf_ptr = (char *)(p->data);
343 p->flag_buf_ptr = (unsigned char *)p->char_buf_ptr + size;
344 tty->buf.memory_used += size;
349 * tty_buffer_free - free a tty buffer
350 * @tty: tty owning the buffer
351 * @b: the buffer to free
353 * Free a tty buffer, or add it to the free list according to our
356 * Locking: Caller must hold tty->buf.lock
359 static void tty_buffer_free(struct tty_struct *tty, struct tty_buffer *b)
361 /* Dumb strategy for now - should keep some stats */
362 tty->buf.memory_used -= b->size;
363 WARN_ON(tty->buf.memory_used < 0);
368 b->next = tty->buf.free;
374 * __tty_buffer_flush - flush full tty buffers
377 * flush all the buffers containing receive data. Caller must
378 * hold the buffer lock and must have ensured no parallel flush to
381 * Locking: Caller must hold tty->buf.lock
384 static void __tty_buffer_flush(struct tty_struct *tty)
386 struct tty_buffer *thead;
388 while ((thead = tty->buf.head) != NULL) {
389 tty->buf.head = thead->next;
390 tty_buffer_free(tty, thead);
392 tty->buf.tail = NULL;
396 * tty_buffer_flush - flush full tty buffers
399 * flush all the buffers containing receive data. If the buffer is
400 * being processed by flush_to_ldisc then we defer the processing
406 static void tty_buffer_flush(struct tty_struct *tty)
409 spin_lock_irqsave(&tty->buf.lock, flags);
411 /* If the data is being pushed to the tty layer then we can't
412 process it here. Instead set a flag and the flush_to_ldisc
413 path will process the flush request before it exits */
414 if (test_bit(TTY_FLUSHING, &tty->flags)) {
415 set_bit(TTY_FLUSHPENDING, &tty->flags);
416 spin_unlock_irqrestore(&tty->buf.lock, flags);
417 wait_event(tty->read_wait,
418 test_bit(TTY_FLUSHPENDING, &tty->flags) == 0);
421 __tty_buffer_flush(tty);
422 spin_unlock_irqrestore(&tty->buf.lock, flags);
426 * tty_buffer_find - find a free tty buffer
427 * @tty: tty owning the buffer
428 * @size: characters wanted
430 * Locate an existing suitable tty buffer or if we are lacking one then
431 * allocate a new one. We round our buffers off in 256 character chunks
432 * to get better allocation behaviour.
434 * Locking: Caller must hold tty->buf.lock
437 static struct tty_buffer *tty_buffer_find(struct tty_struct *tty, size_t size)
439 struct tty_buffer **tbh = &tty->buf.free;
440 while ((*tbh) != NULL) {
441 struct tty_buffer *t = *tbh;
442 if (t->size >= size) {
448 tty->buf.memory_used += t->size;
451 tbh = &((*tbh)->next);
453 /* Round the buffer size out */
454 size = (size + 0xFF) & ~0xFF;
455 return tty_buffer_alloc(tty, size);
456 /* Should possibly check if this fails for the largest buffer we
457 have queued and recycle that ? */
461 * tty_buffer_request_room - grow tty buffer if needed
462 * @tty: tty structure
463 * @size: size desired
465 * Make at least size bytes of linear space available for the tty
466 * buffer. If we fail return the size we managed to find.
468 * Locking: Takes tty->buf.lock
470 int tty_buffer_request_room(struct tty_struct *tty, size_t size)
472 struct tty_buffer *b, *n;
476 spin_lock_irqsave(&tty->buf.lock, flags);
478 /* OPTIMISATION: We could keep a per tty "zero" sized buffer to
479 remove this conditional if its worth it. This would be invisible
481 if ((b = tty->buf.tail) != NULL)
482 left = b->size - b->used;
487 /* This is the slow path - looking for new buffers to use */
488 if ((n = tty_buffer_find(tty, size)) != NULL) {
499 spin_unlock_irqrestore(&tty->buf.lock, flags);
502 EXPORT_SYMBOL_GPL(tty_buffer_request_room);
505 * tty_insert_flip_string - Add characters to the tty buffer
506 * @tty: tty structure
510 * Queue a series of bytes to the tty buffering. All the characters
511 * passed are marked as without error. Returns the number added.
513 * Locking: Called functions may take tty->buf.lock
516 int tty_insert_flip_string(struct tty_struct *tty, const unsigned char *chars,
521 int space = tty_buffer_request_room(tty, size - copied);
522 struct tty_buffer *tb = tty->buf.tail;
523 /* If there is no space then tb may be NULL */
524 if (unlikely(space == 0))
526 memcpy(tb->char_buf_ptr + tb->used, chars, space);
527 memset(tb->flag_buf_ptr + tb->used, TTY_NORMAL, space);
531 /* There is a small chance that we need to split the data over
532 several buffers. If this is the case we must loop */
533 } while (unlikely(size > copied));
536 EXPORT_SYMBOL(tty_insert_flip_string);
539 * tty_insert_flip_string_flags - Add characters to the tty buffer
540 * @tty: tty structure
545 * Queue a series of bytes to the tty buffering. For each character
546 * the flags array indicates the status of the character. Returns the
549 * Locking: Called functions may take tty->buf.lock
552 int tty_insert_flip_string_flags(struct tty_struct *tty,
553 const unsigned char *chars, const char *flags, size_t size)
557 int space = tty_buffer_request_room(tty, size - copied);
558 struct tty_buffer *tb = tty->buf.tail;
559 /* If there is no space then tb may be NULL */
560 if (unlikely(space == 0))
562 memcpy(tb->char_buf_ptr + tb->used, chars, space);
563 memcpy(tb->flag_buf_ptr + tb->used, flags, space);
568 /* There is a small chance that we need to split the data over
569 several buffers. If this is the case we must loop */
570 } while (unlikely(size > copied));
573 EXPORT_SYMBOL(tty_insert_flip_string_flags);
576 * tty_schedule_flip - push characters to ldisc
577 * @tty: tty to push from
579 * Takes any pending buffers and transfers their ownership to the
580 * ldisc side of the queue. It then schedules those characters for
581 * processing by the line discipline.
583 * Locking: Takes tty->buf.lock
586 void tty_schedule_flip(struct tty_struct *tty)
589 spin_lock_irqsave(&tty->buf.lock, flags);
590 if (tty->buf.tail != NULL)
591 tty->buf.tail->commit = tty->buf.tail->used;
592 spin_unlock_irqrestore(&tty->buf.lock, flags);
593 schedule_delayed_work(&tty->buf.work, 1);
595 EXPORT_SYMBOL(tty_schedule_flip);
598 * tty_prepare_flip_string - make room for characters
600 * @chars: return pointer for character write area
601 * @size: desired size
603 * Prepare a block of space in the buffer for data. Returns the length
604 * available and buffer pointer to the space which is now allocated and
605 * accounted for as ready for normal characters. This is used for drivers
606 * that need their own block copy routines into the buffer. There is no
607 * guarantee the buffer is a DMA target!
609 * Locking: May call functions taking tty->buf.lock
612 int tty_prepare_flip_string(struct tty_struct *tty, unsigned char **chars,
615 int space = tty_buffer_request_room(tty, size);
617 struct tty_buffer *tb = tty->buf.tail;
618 *chars = tb->char_buf_ptr + tb->used;
619 memset(tb->flag_buf_ptr + tb->used, TTY_NORMAL, space);
625 EXPORT_SYMBOL_GPL(tty_prepare_flip_string);
628 * tty_prepare_flip_string_flags - make room for characters
630 * @chars: return pointer for character write area
631 * @flags: return pointer for status flag write area
632 * @size: desired size
634 * Prepare a block of space in the buffer for data. Returns the length
635 * available and buffer pointer to the space which is now allocated and
636 * accounted for as ready for characters. This is used for drivers
637 * that need their own block copy routines into the buffer. There is no
638 * guarantee the buffer is a DMA target!
640 * Locking: May call functions taking tty->buf.lock
643 int tty_prepare_flip_string_flags(struct tty_struct *tty,
644 unsigned char **chars, char **flags, size_t size)
646 int space = tty_buffer_request_room(tty, size);
648 struct tty_buffer *tb = tty->buf.tail;
649 *chars = tb->char_buf_ptr + tb->used;
650 *flags = tb->flag_buf_ptr + tb->used;
656 EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags);
661 * tty_set_termios_ldisc - set ldisc field
662 * @tty: tty structure
663 * @num: line discipline number
665 * This is probably overkill for real world processors but
666 * they are not on hot paths so a little discipline won't do
669 * Locking: takes termios_mutex
672 static void tty_set_termios_ldisc(struct tty_struct *tty, int num)
674 mutex_lock(&tty->termios_mutex);
675 tty->termios->c_line = num;
676 mutex_unlock(&tty->termios_mutex);
680 * This guards the refcounted line discipline lists. The lock
681 * must be taken with irqs off because there are hangup path
682 * callers who will do ldisc lookups and cannot sleep.
685 static DEFINE_SPINLOCK(tty_ldisc_lock);
686 static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_wait);
687 /* Line disc dispatch table */
688 static struct tty_ldisc tty_ldiscs[NR_LDISCS];
691 * tty_register_ldisc - install a line discipline
692 * @disc: ldisc number
693 * @new_ldisc: pointer to the ldisc object
695 * Installs a new line discipline into the kernel. The discipline
696 * is set up as unreferenced and then made available to the kernel
697 * from this point onwards.
700 * takes tty_ldisc_lock to guard against ldisc races
703 int tty_register_ldisc(int disc, struct tty_ldisc *new_ldisc)
708 if (disc < N_TTY || disc >= NR_LDISCS)
711 spin_lock_irqsave(&tty_ldisc_lock, flags);
712 tty_ldiscs[disc] = *new_ldisc;
713 tty_ldiscs[disc].num = disc;
714 tty_ldiscs[disc].flags |= LDISC_FLAG_DEFINED;
715 tty_ldiscs[disc].refcount = 0;
716 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
720 EXPORT_SYMBOL(tty_register_ldisc);
723 * tty_unregister_ldisc - unload a line discipline
724 * @disc: ldisc number
725 * @new_ldisc: pointer to the ldisc object
727 * Remove a line discipline from the kernel providing it is not
731 * takes tty_ldisc_lock to guard against ldisc races
734 int tty_unregister_ldisc(int disc)
739 if (disc < N_TTY || disc >= NR_LDISCS)
742 spin_lock_irqsave(&tty_ldisc_lock, flags);
743 if (tty_ldiscs[disc].refcount)
746 tty_ldiscs[disc].flags &= ~LDISC_FLAG_DEFINED;
747 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
751 EXPORT_SYMBOL(tty_unregister_ldisc);
754 * tty_ldisc_get - take a reference to an ldisc
755 * @disc: ldisc number
757 * Takes a reference to a line discipline. Deals with refcounts and
758 * module locking counts. Returns NULL if the discipline is not available.
759 * Returns a pointer to the discipline and bumps the ref count if it is
763 * takes tty_ldisc_lock to guard against ldisc races
766 struct tty_ldisc *tty_ldisc_get(int disc)
769 struct tty_ldisc *ld;
771 if (disc < N_TTY || disc >= NR_LDISCS)
774 spin_lock_irqsave(&tty_ldisc_lock, flags);
776 ld = &tty_ldiscs[disc];
777 /* Check the entry is defined */
778 if (ld->flags & LDISC_FLAG_DEFINED) {
779 /* If the module is being unloaded we can't use it */
780 if (!try_module_get(ld->owner))
786 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
790 EXPORT_SYMBOL_GPL(tty_ldisc_get);
793 * tty_ldisc_put - drop ldisc reference
794 * @disc: ldisc number
796 * Drop a reference to a line discipline. Manage refcounts and
797 * module usage counts
800 * takes tty_ldisc_lock to guard against ldisc races
803 void tty_ldisc_put(int disc)
805 struct tty_ldisc *ld;
808 BUG_ON(disc < N_TTY || disc >= NR_LDISCS);
810 spin_lock_irqsave(&tty_ldisc_lock, flags);
811 ld = &tty_ldiscs[disc];
812 BUG_ON(ld->refcount == 0);
814 module_put(ld->owner);
815 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
818 EXPORT_SYMBOL_GPL(tty_ldisc_put);
821 * tty_ldisc_assign - set ldisc on a tty
822 * @tty: tty to assign
823 * @ld: line discipline
825 * Install an instance of a line discipline into a tty structure. The
826 * ldisc must have a reference count above zero to ensure it remains/
827 * The tty instance refcount starts at zero.
830 * Caller must hold references
833 static void tty_ldisc_assign(struct tty_struct *tty, struct tty_ldisc *ld)
836 tty->ldisc.refcount = 0;
840 * tty_ldisc_try - internal helper
843 * Make a single attempt to grab and bump the refcount on
844 * the tty ldisc. Return 0 on failure or 1 on success. This is
845 * used to implement both the waiting and non waiting versions
848 * Locking: takes tty_ldisc_lock
851 static int tty_ldisc_try(struct tty_struct *tty)
854 struct tty_ldisc *ld;
857 spin_lock_irqsave(&tty_ldisc_lock, flags);
859 if (test_bit(TTY_LDISC, &tty->flags)) {
863 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
868 * tty_ldisc_ref_wait - wait for the tty ldisc
871 * Dereference the line discipline for the terminal and take a
872 * reference to it. If the line discipline is in flux then
873 * wait patiently until it changes.
875 * Note: Must not be called from an IRQ/timer context. The caller
876 * must also be careful not to hold other locks that will deadlock
877 * against a discipline change, such as an existing ldisc reference
878 * (which we check for)
880 * Locking: call functions take tty_ldisc_lock
883 struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty)
885 /* wait_event is a macro */
886 wait_event(tty_ldisc_wait, tty_ldisc_try(tty));
887 if (tty->ldisc.refcount == 0)
888 printk(KERN_ERR "tty_ldisc_ref_wait\n");
892 EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait);
895 * tty_ldisc_ref - get the tty ldisc
898 * Dereference the line discipline for the terminal and take a
899 * reference to it. If the line discipline is in flux then
900 * return NULL. Can be called from IRQ and timer functions.
902 * Locking: called functions take tty_ldisc_lock
905 struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty)
907 if (tty_ldisc_try(tty))
912 EXPORT_SYMBOL_GPL(tty_ldisc_ref);
915 * tty_ldisc_deref - free a tty ldisc reference
916 * @ld: reference to free up
918 * Undoes the effect of tty_ldisc_ref or tty_ldisc_ref_wait. May
919 * be called in IRQ context.
921 * Locking: takes tty_ldisc_lock
924 void tty_ldisc_deref(struct tty_ldisc *ld)
930 spin_lock_irqsave(&tty_ldisc_lock, flags);
931 if (ld->refcount == 0)
932 printk(KERN_ERR "tty_ldisc_deref: no references.\n");
935 if (ld->refcount == 0)
936 wake_up(&tty_ldisc_wait);
937 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
940 EXPORT_SYMBOL_GPL(tty_ldisc_deref);
943 * tty_ldisc_enable - allow ldisc use
944 * @tty: terminal to activate ldisc on
946 * Set the TTY_LDISC flag when the line discipline can be called
947 * again. Do necessary wakeups for existing sleepers.
949 * Note: nobody should set this bit except via this function. Clearing
950 * directly is allowed.
953 static void tty_ldisc_enable(struct tty_struct *tty)
955 set_bit(TTY_LDISC, &tty->flags);
956 wake_up(&tty_ldisc_wait);
960 * tty_set_ldisc - set line discipline
961 * @tty: the terminal to set
962 * @ldisc: the line discipline
964 * Set the discipline of a tty line. Must be called from a process
967 * Locking: takes tty_ldisc_lock.
968 * called functions take termios_mutex
971 static int tty_set_ldisc(struct tty_struct *tty, int ldisc)
974 struct tty_ldisc o_ldisc;
978 struct tty_ldisc *ld;
979 struct tty_struct *o_tty;
981 if ((ldisc < N_TTY) || (ldisc >= NR_LDISCS))
986 ld = tty_ldisc_get(ldisc);
987 /* Eduardo Blanco <ejbs@cs.cs.com.uy> */
988 /* Cyrus Durgin <cider@speakeasy.org> */
990 request_module("tty-ldisc-%d", ldisc);
991 ld = tty_ldisc_get(ldisc);
997 * Problem: What do we do if this blocks ?
1000 tty_wait_until_sent(tty, 0);
1002 if (tty->ldisc.num == ldisc) {
1003 tty_ldisc_put(ldisc);
1008 * No more input please, we are switching. The new ldisc
1009 * will update this value in the ldisc open function
1012 tty->receive_room = 0;
1014 o_ldisc = tty->ldisc;
1018 * Make sure we don't change while someone holds a
1019 * reference to the line discipline. The TTY_LDISC bit
1020 * prevents anyone taking a reference once it is clear.
1021 * We need the lock to avoid racing reference takers.
1024 spin_lock_irqsave(&tty_ldisc_lock, flags);
1025 if (tty->ldisc.refcount || (o_tty && o_tty->ldisc.refcount)) {
1026 if (tty->ldisc.refcount) {
1027 /* Free the new ldisc we grabbed. Must drop the lock
1029 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
1030 tty_ldisc_put(ldisc);
1032 * There are several reasons we may be busy, including
1033 * random momentary I/O traffic. We must therefore
1034 * retry. We could distinguish between blocking ops
1035 * and retries if we made tty_ldisc_wait() smarter.
1036 * That is up for discussion.
1038 if (wait_event_interruptible(tty_ldisc_wait, tty->ldisc.refcount == 0) < 0)
1039 return -ERESTARTSYS;
1042 if (o_tty && o_tty->ldisc.refcount) {
1043 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
1044 tty_ldisc_put(ldisc);
1045 if (wait_event_interruptible(tty_ldisc_wait, o_tty->ldisc.refcount == 0) < 0)
1046 return -ERESTARTSYS;
1051 * If the TTY_LDISC bit is set, then we are racing against
1052 * another ldisc change
1054 if (!test_bit(TTY_LDISC, &tty->flags)) {
1055 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
1056 tty_ldisc_put(ldisc);
1057 ld = tty_ldisc_ref_wait(tty);
1058 tty_ldisc_deref(ld);
1062 clear_bit(TTY_LDISC, &tty->flags);
1064 clear_bit(TTY_LDISC, &o_tty->flags);
1065 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
1068 * From this point on we know nobody has an ldisc
1069 * usage reference, nor can they obtain one until
1070 * we say so later on.
1073 work = cancel_delayed_work(&tty->buf.work);
1075 * Wait for ->hangup_work and ->buf.work handlers to terminate
1077 flush_scheduled_work();
1078 /* Shutdown the current discipline. */
1079 if (tty->ldisc.close)
1080 (tty->ldisc.close)(tty);
1082 /* Now set up the new line discipline. */
1083 tty_ldisc_assign(tty, ld);
1084 tty_set_termios_ldisc(tty, ldisc);
1085 if (tty->ldisc.open)
1086 retval = (tty->ldisc.open)(tty);
1088 tty_ldisc_put(ldisc);
1089 /* There is an outstanding reference here so this is safe */
1090 tty_ldisc_assign(tty, tty_ldisc_get(o_ldisc.num));
1091 tty_set_termios_ldisc(tty, tty->ldisc.num);
1092 if (tty->ldisc.open && (tty->ldisc.open(tty) < 0)) {
1093 tty_ldisc_put(o_ldisc.num);
1094 /* This driver is always present */
1095 tty_ldisc_assign(tty, tty_ldisc_get(N_TTY));
1096 tty_set_termios_ldisc(tty, N_TTY);
1097 if (tty->ldisc.open) {
1098 int r = tty->ldisc.open(tty);
1101 panic("Couldn't open N_TTY ldisc for "
1103 tty_name(tty, buf), r);
1107 /* At this point we hold a reference to the new ldisc and a
1108 a reference to the old ldisc. If we ended up flipping back
1109 to the existing ldisc we have two references to it */
1111 if (tty->ldisc.num != o_ldisc.num && tty->driver->set_ldisc)
1112 tty->driver->set_ldisc(tty);
1114 tty_ldisc_put(o_ldisc.num);
1117 * Allow ldisc referencing to occur as soon as the driver
1118 * ldisc callback completes.
1121 tty_ldisc_enable(tty);
1123 tty_ldisc_enable(o_tty);
1125 /* Restart it in case no characters kick it off. Safe if
1128 schedule_delayed_work(&tty->buf.work, 1);
1133 * get_tty_driver - find device of a tty
1134 * @dev_t: device identifier
1135 * @index: returns the index of the tty
1137 * This routine returns a tty driver structure, given a device number
1138 * and also passes back the index number.
1140 * Locking: caller must hold tty_mutex
1143 static struct tty_driver *get_tty_driver(dev_t device, int *index)
1145 struct tty_driver *p;
1147 list_for_each_entry(p, &tty_drivers, tty_drivers) {
1148 dev_t base = MKDEV(p->major, p->minor_start);
1149 if (device < base || device >= base + p->num)
1151 *index = device - base;
1157 #ifdef CONFIG_CONSOLE_POLL
1160 * tty_find_polling_driver - find device of a polled tty
1161 * @name: name string to match
1162 * @line: pointer to resulting tty line nr
1164 * This routine returns a tty driver structure, given a name
1165 * and the condition that the tty driver is capable of polled
1168 struct tty_driver *tty_find_polling_driver(char *name, int *line)
1170 struct tty_driver *p, *res = NULL;
1174 mutex_lock(&tty_mutex);
1175 /* Search through the tty devices to look for a match */
1176 list_for_each_entry(p, &tty_drivers, tty_drivers) {
1177 str = name + strlen(p->name);
1178 tty_line = simple_strtoul(str, &str, 10);
1184 if (tty_line >= 0 && tty_line <= p->num && p->poll_init &&
1185 !p->poll_init(p, tty_line, str)) {
1192 mutex_unlock(&tty_mutex);
1196 EXPORT_SYMBOL_GPL(tty_find_polling_driver);
1200 * tty_check_change - check for POSIX terminal changes
1201 * @tty: tty to check
1203 * If we try to write to, or set the state of, a terminal and we're
1204 * not in the foreground, send a SIGTTOU. If the signal is blocked or
1205 * ignored, go ahead and perform the operation. (POSIX 7.2)
1207 * Locking: ctrl_lock - FIXME: review this
1210 int tty_check_change(struct tty_struct *tty)
1212 unsigned long flags;
1215 if (current->signal->tty != tty)
1218 spin_lock_irqsave(&tty->ctrl_lock, flags);
1221 printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");
1224 if (task_pgrp(current) == tty->pgrp)
1226 if (is_ignored(SIGTTOU))
1228 if (is_current_pgrp_orphaned()) {
1232 kill_pgrp(task_pgrp(current), SIGTTOU, 1);
1233 set_thread_flag(TIF_SIGPENDING);
1236 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
1240 EXPORT_SYMBOL(tty_check_change);
1242 static ssize_t hung_up_tty_read(struct file *file, char __user *buf,
1243 size_t count, loff_t *ppos)
1248 static ssize_t hung_up_tty_write(struct file *file, const char __user *buf,
1249 size_t count, loff_t *ppos)
1254 /* No kernel lock held - none needed ;) */
1255 static unsigned int hung_up_tty_poll(struct file *filp, poll_table *wait)
1257 return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM;
1260 static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
1263 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
1266 static long hung_up_tty_compat_ioctl(struct file *file,
1267 unsigned int cmd, unsigned long arg)
1269 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
1272 static const struct file_operations tty_fops = {
1273 .llseek = no_llseek,
1277 .unlocked_ioctl = tty_ioctl,
1278 .compat_ioctl = tty_compat_ioctl,
1280 .release = tty_release,
1281 .fasync = tty_fasync,
1284 #ifdef CONFIG_UNIX98_PTYS
1285 static const struct file_operations ptmx_fops = {
1286 .llseek = no_llseek,
1290 .unlocked_ioctl = tty_ioctl,
1291 .compat_ioctl = tty_compat_ioctl,
1293 .release = tty_release,
1294 .fasync = tty_fasync,
1298 static const struct file_operations console_fops = {
1299 .llseek = no_llseek,
1301 .write = redirected_tty_write,
1303 .unlocked_ioctl = tty_ioctl,
1304 .compat_ioctl = tty_compat_ioctl,
1306 .release = tty_release,
1307 .fasync = tty_fasync,
1310 static const struct file_operations hung_up_tty_fops = {
1311 .llseek = no_llseek,
1312 .read = hung_up_tty_read,
1313 .write = hung_up_tty_write,
1314 .poll = hung_up_tty_poll,
1315 .unlocked_ioctl = hung_up_tty_ioctl,
1316 .compat_ioctl = hung_up_tty_compat_ioctl,
1317 .release = tty_release,
1320 static DEFINE_SPINLOCK(redirect_lock);
1321 static struct file *redirect;
1324 * tty_wakeup - request more data
1327 * Internal and external helper for wakeups of tty. This function
1328 * informs the line discipline if present that the driver is ready
1329 * to receive more output data.
1332 void tty_wakeup(struct tty_struct *tty)
1334 struct tty_ldisc *ld;
1336 if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
1337 ld = tty_ldisc_ref(tty);
1339 if (ld->write_wakeup)
1340 ld->write_wakeup(tty);
1341 tty_ldisc_deref(ld);
1344 wake_up_interruptible(&tty->write_wait);
1347 EXPORT_SYMBOL_GPL(tty_wakeup);
1350 * tty_ldisc_flush - flush line discipline queue
1353 * Flush the line discipline queue (if any) for this tty. If there
1354 * is no line discipline active this is a no-op.
1357 void tty_ldisc_flush(struct tty_struct *tty)
1359 struct tty_ldisc *ld = tty_ldisc_ref(tty);
1361 if (ld->flush_buffer)
1362 ld->flush_buffer(tty);
1363 tty_ldisc_deref(ld);
1365 tty_buffer_flush(tty);
1368 EXPORT_SYMBOL_GPL(tty_ldisc_flush);
1371 * tty_reset_termios - reset terminal state
1372 * @tty: tty to reset
1374 * Restore a terminal to the driver default state
1377 static void tty_reset_termios(struct tty_struct *tty)
1379 mutex_lock(&tty->termios_mutex);
1380 *tty->termios = tty->driver->init_termios;
1381 tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
1382 tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
1383 mutex_unlock(&tty->termios_mutex);
1387 * do_tty_hangup - actual handler for hangup events
1390 * This can be called by the "eventd" kernel thread. That is process
1391 * synchronous but doesn't hold any locks, so we need to make sure we
1392 * have the appropriate locks for what we're doing.
1394 * The hangup event clears any pending redirections onto the hung up
1395 * device. It ensures future writes will error and it does the needed
1396 * line discipline hangup and signal delivery. The tty object itself
1401 * redirect lock for undoing redirection
1402 * file list lock for manipulating list of ttys
1403 * tty_ldisc_lock from called functions
1404 * termios_mutex resetting termios data
1405 * tasklist_lock to walk task list for hangup event
1406 * ->siglock to protect ->signal/->sighand
1408 static void do_tty_hangup(struct work_struct *work)
1410 struct tty_struct *tty =
1411 container_of(work, struct tty_struct, hangup_work);
1412 struct file *cons_filp = NULL;
1413 struct file *filp, *f = NULL;
1414 struct task_struct *p;
1415 struct tty_ldisc *ld;
1416 int closecount = 0, n;
1417 unsigned long flags;
1422 /* inuse_filps is protected by the single kernel lock */
1425 spin_lock(&redirect_lock);
1426 if (redirect && redirect->private_data == tty) {
1430 spin_unlock(&redirect_lock);
1432 check_tty_count(tty, "do_tty_hangup");
1434 /* This breaks for file handles being sent over AF_UNIX sockets ? */
1435 list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) {
1436 if (filp->f_op->write == redirected_tty_write)
1438 if (filp->f_op->write != tty_write)
1441 tty_fasync(-1, filp, 0); /* can't block */
1442 filp->f_op = &hung_up_tty_fops;
1446 * FIXME! What are the locking issues here? This may me overdoing
1447 * things... This question is especially important now that we've
1448 * removed the irqlock.
1450 ld = tty_ldisc_ref(tty);
1452 /* We may have no line discipline at this point */
1453 if (ld->flush_buffer)
1454 ld->flush_buffer(tty);
1455 if (tty->driver->flush_buffer)
1456 tty->driver->flush_buffer(tty);
1457 if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) &&
1459 ld->write_wakeup(tty);
1464 * FIXME: Once we trust the LDISC code better we can wait here for
1465 * ldisc completion and fix the driver call race
1467 wake_up_interruptible(&tty->write_wait);
1468 wake_up_interruptible(&tty->read_wait);
1470 * Shutdown the current line discipline, and reset it to
1473 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1474 tty_reset_termios(tty);
1475 /* Defer ldisc switch */
1476 /* tty_deferred_ldisc_switch(N_TTY);
1478 This should get done automatically when the port closes and
1479 tty_release is called */
1481 read_lock(&tasklist_lock);
1483 do_each_pid_task(tty->session, PIDTYPE_SID, p) {
1484 spin_lock_irq(&p->sighand->siglock);
1485 if (p->signal->tty == tty)
1486 p->signal->tty = NULL;
1487 if (!p->signal->leader) {
1488 spin_unlock_irq(&p->sighand->siglock);
1491 __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
1492 __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
1493 put_pid(p->signal->tty_old_pgrp); /* A noop */
1494 spin_lock_irqsave(&tty->ctrl_lock, flags);
1496 p->signal->tty_old_pgrp = get_pid(tty->pgrp);
1497 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
1498 spin_unlock_irq(&p->sighand->siglock);
1499 } while_each_pid_task(tty->session, PIDTYPE_SID, p);
1501 read_unlock(&tasklist_lock);
1503 spin_lock_irqsave(&tty->ctrl_lock, flags);
1505 put_pid(tty->session);
1507 tty->session = NULL;
1509 tty->ctrl_status = 0;
1510 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
1513 * If one of the devices matches a console pointer, we
1514 * cannot just call hangup() because that will cause
1515 * tty->count and state->count to go out of sync.
1516 * So we just call close() the right number of times.
1519 if (tty->driver->close)
1520 for (n = 0; n < closecount; n++)
1521 tty->driver->close(tty, cons_filp);
1522 } else if (tty->driver->hangup)
1523 (tty->driver->hangup)(tty);
1525 * We don't want to have driver/ldisc interactions beyond
1526 * the ones we did here. The driver layer expects no
1527 * calls after ->hangup() from the ldisc side. However we
1528 * can't yet guarantee all that.
1530 set_bit(TTY_HUPPED, &tty->flags);
1532 tty_ldisc_enable(tty);
1533 tty_ldisc_deref(ld);
1541 * tty_hangup - trigger a hangup event
1542 * @tty: tty to hangup
1544 * A carrier loss (virtual or otherwise) has occurred on this like
1545 * schedule a hangup sequence to run after this event.
1548 void tty_hangup(struct tty_struct *tty)
1550 #ifdef TTY_DEBUG_HANGUP
1552 printk(KERN_DEBUG "%s hangup...\n", tty_name(tty, buf));
1554 schedule_work(&tty->hangup_work);
1557 EXPORT_SYMBOL(tty_hangup);
1560 * tty_vhangup - process vhangup
1561 * @tty: tty to hangup
1563 * The user has asked via system call for the terminal to be hung up.
1564 * We do this synchronously so that when the syscall returns the process
1565 * is complete. That guarantee is necessary for security reasons.
1568 void tty_vhangup(struct tty_struct *tty)
1570 #ifdef TTY_DEBUG_HANGUP
1573 printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf));
1575 do_tty_hangup(&tty->hangup_work);
1578 EXPORT_SYMBOL(tty_vhangup);
1581 * tty_hung_up_p - was tty hung up
1582 * @filp: file pointer of tty
1584 * Return true if the tty has been subject to a vhangup or a carrier
1588 int tty_hung_up_p(struct file *filp)
1590 return (filp->f_op == &hung_up_tty_fops);
1593 EXPORT_SYMBOL(tty_hung_up_p);
1596 * is_tty - checker whether file is a TTY
1597 * @filp: file handle that may be a tty
1599 * Check if the file handle is a tty handle.
1602 int is_tty(struct file *filp)
1604 return filp->f_op->read == tty_read
1605 || filp->f_op->read == hung_up_tty_read;
1608 static void session_clear_tty(struct pid *session)
1610 struct task_struct *p;
1611 do_each_pid_task(session, PIDTYPE_SID, p) {
1613 } while_each_pid_task(session, PIDTYPE_SID, p);
1617 * disassociate_ctty - disconnect controlling tty
1618 * @on_exit: true if exiting so need to "hang up" the session
1620 * This function is typically called only by the session leader, when
1621 * it wants to disassociate itself from its controlling tty.
1623 * It performs the following functions:
1624 * (1) Sends a SIGHUP and SIGCONT to the foreground process group
1625 * (2) Clears the tty from being controlling the session
1626 * (3) Clears the controlling tty for all processes in the
1629 * The argument on_exit is set to 1 if called when a process is
1630 * exiting; it is 0 if called by the ioctl TIOCNOTTY.
1633 * BKL is taken for hysterical raisins
1634 * tty_mutex is taken to protect tty
1635 * ->siglock is taken to protect ->signal/->sighand
1636 * tasklist_lock is taken to walk process list for sessions
1637 * ->siglock is taken to protect ->signal/->sighand
1640 void disassociate_ctty(int on_exit)
1642 struct tty_struct *tty;
1643 struct pid *tty_pgrp = NULL;
1646 mutex_lock(&tty_mutex);
1647 tty = get_current_tty();
1649 tty_pgrp = get_pid(tty->pgrp);
1650 mutex_unlock(&tty_mutex);
1652 /* XXX: here we race, there is nothing protecting tty */
1653 if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)
1656 } else if (on_exit) {
1657 struct pid *old_pgrp;
1658 spin_lock_irq(¤t->sighand->siglock);
1659 old_pgrp = current->signal->tty_old_pgrp;
1660 current->signal->tty_old_pgrp = NULL;
1661 spin_unlock_irq(¤t->sighand->siglock);
1663 kill_pgrp(old_pgrp, SIGHUP, on_exit);
1664 kill_pgrp(old_pgrp, SIGCONT, on_exit);
1667 mutex_unlock(&tty_mutex);
1671 kill_pgrp(tty_pgrp, SIGHUP, on_exit);
1673 kill_pgrp(tty_pgrp, SIGCONT, on_exit);
1677 spin_lock_irq(¤t->sighand->siglock);
1678 put_pid(current->signal->tty_old_pgrp);
1679 current->signal->tty_old_pgrp = NULL;
1680 spin_unlock_irq(¤t->sighand->siglock);
1682 mutex_lock(&tty_mutex);
1683 /* It is possible that do_tty_hangup has free'd this tty */
1684 tty = get_current_tty();
1686 unsigned long flags;
1687 spin_lock_irqsave(&tty->ctrl_lock, flags);
1688 put_pid(tty->session);
1690 tty->session = NULL;
1692 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
1694 #ifdef TTY_DEBUG_HANGUP
1695 printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
1699 mutex_unlock(&tty_mutex);
1701 /* Now clear signal->tty under the lock */
1702 read_lock(&tasklist_lock);
1703 session_clear_tty(task_session(current));
1704 read_unlock(&tasklist_lock);
1709 * no_tty - Ensure the current process does not have a controlling tty
1713 struct task_struct *tsk = current;
1715 if (tsk->signal->leader)
1716 disassociate_ctty(0);
1718 proc_clear_tty(tsk);
1723 * stop_tty - propagate flow control
1726 * Perform flow control to the driver. For PTY/TTY pairs we
1727 * must also propagate the TIOCKPKT status. May be called
1728 * on an already stopped device and will not re-call the driver
1731 * This functionality is used by both the line disciplines for
1732 * halting incoming flow and by the driver. It may therefore be
1733 * called from any context, may be under the tty atomic_write_lock
1737 * Uses the tty control lock internally
1740 void stop_tty(struct tty_struct *tty)
1742 unsigned long flags;
1743 spin_lock_irqsave(&tty->ctrl_lock, flags);
1745 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
1749 if (tty->link && tty->link->packet) {
1750 tty->ctrl_status &= ~TIOCPKT_START;
1751 tty->ctrl_status |= TIOCPKT_STOP;
1752 wake_up_interruptible(&tty->link->read_wait);
1754 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
1755 if (tty->driver->stop)
1756 (tty->driver->stop)(tty);
1759 EXPORT_SYMBOL(stop_tty);
1762 * start_tty - propagate flow control
1763 * @tty: tty to start
1765 * Start a tty that has been stopped if at all possible. Perform
1766 * any necessary wakeups and propagate the TIOCPKT status. If this
1767 * is the tty was previous stopped and is being started then the
1768 * driver start method is invoked and the line discipline woken.
1774 void start_tty(struct tty_struct *tty)
1776 unsigned long flags;
1777 spin_lock_irqsave(&tty->ctrl_lock, flags);
1778 if (!tty->stopped || tty->flow_stopped) {
1779 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
1783 if (tty->link && tty->link->packet) {
1784 tty->ctrl_status &= ~TIOCPKT_STOP;
1785 tty->ctrl_status |= TIOCPKT_START;
1786 wake_up_interruptible(&tty->link->read_wait);
1788 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
1789 if (tty->driver->start)
1790 (tty->driver->start)(tty);
1791 /* If we have a running line discipline it may need kicking */
1795 EXPORT_SYMBOL(start_tty);
1798 * tty_read - read method for tty device files
1799 * @file: pointer to tty file
1801 * @count: size of user buffer
1804 * Perform the read system call function on this terminal device. Checks
1805 * for hung up devices before calling the line discipline method.
1808 * Locks the line discipline internally while needed. Multiple
1809 * read calls may be outstanding in parallel.
1812 static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
1816 struct tty_struct *tty;
1817 struct inode *inode;
1818 struct tty_ldisc *ld;
1820 tty = (struct tty_struct *)file->private_data;
1821 inode = file->f_path.dentry->d_inode;
1822 if (tty_paranoia_check(tty, inode, "tty_read"))
1824 if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags)))
1827 /* We want to wait for the line discipline to sort out in this
1829 ld = tty_ldisc_ref_wait(tty);
1831 i = (ld->read)(tty, file, buf, count);
1834 tty_ldisc_deref(ld);
1836 inode->i_atime = current_fs_time(inode->i_sb);
1840 void tty_write_unlock(struct tty_struct *tty)
1842 mutex_unlock(&tty->atomic_write_lock);
1843 wake_up_interruptible(&tty->write_wait);
1846 int tty_write_lock(struct tty_struct *tty, int ndelay)
1848 if (!mutex_trylock(&tty->atomic_write_lock)) {
1851 if (mutex_lock_interruptible(&tty->atomic_write_lock))
1852 return -ERESTARTSYS;
1858 * Split writes up in sane blocksizes to avoid
1859 * denial-of-service type attacks
1861 static inline ssize_t do_tty_write(
1862 ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
1863 struct tty_struct *tty,
1865 const char __user *buf,
1868 ssize_t ret, written = 0;
1871 ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
1876 * We chunk up writes into a temporary buffer. This
1877 * simplifies low-level drivers immensely, since they
1878 * don't have locking issues and user mode accesses.
1880 * But if TTY_NO_WRITE_SPLIT is set, we should use a
1883 * The default chunk-size is 2kB, because the NTTY
1884 * layer has problems with bigger chunks. It will
1885 * claim to be able to handle more characters than
1888 * FIXME: This can probably go away now except that 64K chunks
1889 * are too likely to fail unless switched to vmalloc...
1892 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
1897 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
1898 if (tty->write_cnt < chunk) {
1904 buf = kmalloc(chunk, GFP_KERNEL);
1909 kfree(tty->write_buf);
1910 tty->write_cnt = chunk;
1911 tty->write_buf = buf;
1914 /* Do the write .. */
1916 size_t size = count;
1920 if (copy_from_user(tty->write_buf, buf, size))
1922 ret = write(tty, file, tty->write_buf, size);
1931 if (signal_pending(current))
1936 struct inode *inode = file->f_path.dentry->d_inode;
1937 inode->i_mtime = current_fs_time(inode->i_sb);
1941 tty_write_unlock(tty);
1947 * tty_write - write method for tty device file
1948 * @file: tty file pointer
1949 * @buf: user data to write
1950 * @count: bytes to write
1953 * Write data to a tty device via the line discipline.
1956 * Locks the line discipline as required
1957 * Writes to the tty driver are serialized by the atomic_write_lock
1958 * and are then processed in chunks to the device. The line discipline
1959 * write method will not be involked in parallel for each device
1960 * The line discipline write method is called under the big
1961 * kernel lock for historical reasons. New code should not rely on this.
1964 static ssize_t tty_write(struct file *file, const char __user *buf,
1965 size_t count, loff_t *ppos)
1967 struct tty_struct *tty;
1968 struct inode *inode = file->f_path.dentry->d_inode;
1970 struct tty_ldisc *ld;
1972 tty = (struct tty_struct *)file->private_data;
1973 if (tty_paranoia_check(tty, inode, "tty_write"))
1975 if (!tty || !tty->driver->write ||
1976 (test_bit(TTY_IO_ERROR, &tty->flags)))
1979 ld = tty_ldisc_ref_wait(tty);
1983 ret = do_tty_write(ld->write, tty, file, buf, count);
1984 tty_ldisc_deref(ld);
1988 ssize_t redirected_tty_write(struct file *file, const char __user *buf,
1989 size_t count, loff_t *ppos)
1991 struct file *p = NULL;
1993 spin_lock(&redirect_lock);
1998 spin_unlock(&redirect_lock);
2002 res = vfs_write(p, buf, count, &p->f_pos);
2006 return tty_write(file, buf, count, ppos);
2009 static char ptychar[] = "pqrstuvwxyzabcde";
2012 * pty_line_name - generate name for a pty
2013 * @driver: the tty driver in use
2014 * @index: the minor number
2015 * @p: output buffer of at least 6 bytes
2017 * Generate a name from a driver reference and write it to the output
2022 static void pty_line_name(struct tty_driver *driver, int index, char *p)
2024 int i = index + driver->name_base;
2025 /* ->name is initialized to "ttyp", but "tty" is expected */
2026 sprintf(p, "%s%c%x",
2027 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
2028 ptychar[i >> 4 & 0xf], i & 0xf);
2032 * pty_line_name - generate name for a tty
2033 * @driver: the tty driver in use
2034 * @index: the minor number
2035 * @p: output buffer of at least 7 bytes
2037 * Generate a name from a driver reference and write it to the output
2042 static void tty_line_name(struct tty_driver *driver, int index, char *p)
2044 sprintf(p, "%s%d", driver->name, index + driver->name_base);
2048 * init_dev - initialise a tty device
2049 * @driver: tty driver we are opening a device on
2050 * @idx: device index
2051 * @tty: returned tty structure
2053 * Prepare a tty device. This may not be a "new" clean device but
2054 * could also be an active device. The pty drivers require special
2055 * handling because of this.
2058 * The function is called under the tty_mutex, which
2059 * protects us from the tty struct or driver itself going away.
2061 * On exit the tty device has the line discipline attached and
2062 * a reference count of 1. If a pair was created for pty/tty use
2063 * and the other was a pty master then it too has a reference count of 1.
2065 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
2066 * failed open. The new code protects the open with a mutex, so it's
2067 * really quite straightforward. The mutex locking can probably be
2068 * relaxed for the (most common) case of reopening a tty.
2071 static int init_dev(struct tty_driver *driver, int idx,
2072 struct tty_struct **ret_tty)
2074 struct tty_struct *tty, *o_tty;
2075 struct ktermios *tp, **tp_loc, *o_tp, **o_tp_loc;
2076 struct ktermios *ltp, **ltp_loc, *o_ltp, **o_ltp_loc;
2079 /* check whether we're reopening an existing tty */
2080 if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
2081 tty = devpts_get_tty(idx);
2083 * If we don't have a tty here on a slave open, it's because
2084 * the master already started the close process and there's
2085 * no relation between devpts file and tty anymore.
2087 if (!tty && driver->subtype == PTY_TYPE_SLAVE) {
2092 * It's safe from now on because init_dev() is called with
2093 * tty_mutex held and release_dev() won't change tty->count
2094 * or tty->flags without having to grab tty_mutex
2096 if (tty && driver->subtype == PTY_TYPE_MASTER)
2099 tty = driver->ttys[idx];
2101 if (tty) goto fast_track;
2104 * First time open is complex, especially for PTY devices.
2105 * This code guarantees that either everything succeeds and the
2106 * TTY is ready for operation, or else the table slots are vacated
2107 * and the allocated memory released. (Except that the termios
2108 * and locked termios may be retained.)
2111 if (!try_module_get(driver->owner)) {
2120 tty = alloc_tty_struct();
2123 initialize_tty_struct(tty);
2124 tty->driver = driver;
2126 tty_line_name(driver, idx, tty->name);
2128 if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
2129 tp_loc = &tty->termios;
2130 ltp_loc = &tty->termios_locked;
2132 tp_loc = &driver->termios[idx];
2133 ltp_loc = &driver->termios_locked[idx];
2137 tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
2140 *tp = driver->init_termios;
2144 ltp = kzalloc(sizeof(struct ktermios), GFP_KERNEL);
2149 if (driver->type == TTY_DRIVER_TYPE_PTY) {
2150 o_tty = alloc_tty_struct();
2153 initialize_tty_struct(o_tty);
2154 o_tty->driver = driver->other;
2156 tty_line_name(driver->other, idx, o_tty->name);
2158 if (driver->flags & TTY_DRIVER_DEVPTS_MEM) {
2159 o_tp_loc = &o_tty->termios;
2160 o_ltp_loc = &o_tty->termios_locked;
2162 o_tp_loc = &driver->other->termios[idx];
2163 o_ltp_loc = &driver->other->termios_locked[idx];
2167 o_tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
2170 *o_tp = driver->other->init_termios;
2174 o_ltp = kzalloc(sizeof(struct ktermios), GFP_KERNEL);
2180 * Everything allocated ... set up the o_tty structure.
2182 if (!(driver->other->flags & TTY_DRIVER_DEVPTS_MEM))
2183 driver->other->ttys[idx] = o_tty;
2188 o_tty->termios = *o_tp_loc;
2189 o_tty->termios_locked = *o_ltp_loc;
2190 driver->other->refcount++;
2191 if (driver->subtype == PTY_TYPE_MASTER)
2194 /* Establish the links in both directions */
2200 * All structures have been allocated, so now we install them.
2201 * Failures after this point use release_tty to clean up, so
2202 * there's no need to null out the local pointers.
2204 if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM))
2205 driver->ttys[idx] = tty;
2211 tty->termios = *tp_loc;
2212 tty->termios_locked = *ltp_loc;
2213 /* Compatibility until drivers always set this */
2214 tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
2215 tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
2220 * Structures all installed ... call the ldisc open routines.
2221 * If we fail here just call release_tty to clean up. No need
2222 * to decrement the use counts, as release_tty doesn't care.
2225 if (tty->ldisc.open) {
2226 retval = (tty->ldisc.open)(tty);
2228 goto release_mem_out;
2230 if (o_tty && o_tty->ldisc.open) {
2231 retval = (o_tty->ldisc.open)(o_tty);
2233 if (tty->ldisc.close)
2234 (tty->ldisc.close)(tty);
2235 goto release_mem_out;
2237 tty_ldisc_enable(o_tty);
2239 tty_ldisc_enable(tty);
2243 * This fast open can be used if the tty is already open.
2244 * No memory is allocated, and the only failures are from
2245 * attempting to open a closing tty or attempting multiple
2246 * opens on a pty master.
2249 if (test_bit(TTY_CLOSING, &tty->flags)) {
2253 if (driver->type == TTY_DRIVER_TYPE_PTY &&
2254 driver->subtype == PTY_TYPE_MASTER) {
2256 * special case for PTY masters: only one open permitted,
2257 * and the slave side open count is incremented as well.
2266 tty->driver = driver; /* N.B. why do this every time?? */
2269 if (!test_bit(TTY_LDISC, &tty->flags))
2270 printk(KERN_ERR "init_dev but no ldisc\n");
2274 /* All paths come through here to release the mutex */
2278 /* Release locally allocated memory ... nothing placed in slots */
2282 free_tty_struct(o_tty);
2285 free_tty_struct(tty);
2288 module_put(driver->owner);
2292 /* call the tty release_tty routine to clean out this slot */
2294 if (printk_ratelimit())
2295 printk(KERN_INFO "init_dev: ldisc open failed, "
2296 "clearing slot %d\n", idx);
2297 release_tty(tty, idx);
2302 * release_one_tty - release tty structure memory
2304 * Releases memory associated with a tty structure, and clears out the
2305 * driver table slots. This function is called when a device is no longer
2306 * in use. It also gets called when setup of a device fails.
2309 * tty_mutex - sometimes only
2310 * takes the file list lock internally when working on the list
2311 * of ttys that the driver keeps.
2312 * FIXME: should we require tty_mutex is held here ??
2314 static void release_one_tty(struct tty_struct *tty, int idx)
2316 int devpts = tty->driver->flags & TTY_DRIVER_DEVPTS_MEM;
2317 struct ktermios *tp;
2320 tty->driver->ttys[idx] = NULL;
2322 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
2325 tty->driver->termios[idx] = NULL;
2328 tp = tty->termios_locked;
2330 tty->driver->termios_locked[idx] = NULL;
2336 tty->driver->refcount--;
2339 list_del_init(&tty->tty_files);
2342 free_tty_struct(tty);
2346 * release_tty - release tty structure memory
2348 * Release both @tty and a possible linked partner (think pty pair),
2349 * and decrement the refcount of the backing module.
2352 * tty_mutex - sometimes only
2353 * takes the file list lock internally when working on the list
2354 * of ttys that the driver keeps.
2355 * FIXME: should we require tty_mutex is held here ??
2357 static void release_tty(struct tty_struct *tty, int idx)
2359 struct tty_driver *driver = tty->driver;
2362 release_one_tty(tty->link, idx);
2363 release_one_tty(tty, idx);
2364 module_put(driver->owner);
2368 * Even releasing the tty structures is a tricky business.. We have
2369 * to be very careful that the structures are all released at the
2370 * same time, as interrupts might otherwise get the wrong pointers.
2372 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
2373 * lead to double frees or releasing memory still in use.
2375 static void release_dev(struct file *filp)
2377 struct tty_struct *tty, *o_tty;
2378 int pty_master, tty_closing, o_tty_closing, do_sleep;
2382 unsigned long flags;
2384 tty = (struct tty_struct *)filp->private_data;
2385 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode,
2389 check_tty_count(tty, "release_dev");
2391 tty_fasync(-1, filp, 0);
2394 pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2395 tty->driver->subtype == PTY_TYPE_MASTER);
2396 devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0;
2399 #ifdef TTY_PARANOIA_CHECK
2400 if (idx < 0 || idx >= tty->driver->num) {
2401 printk(KERN_DEBUG "release_dev: bad idx when trying to "
2402 "free (%s)\n", tty->name);
2405 if (!(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
2406 if (tty != tty->driver->ttys[idx]) {
2407 printk(KERN_DEBUG "release_dev: driver.table[%d] not tty "
2408 "for (%s)\n", idx, tty->name);
2411 if (tty->termios != tty->driver->termios[idx]) {
2412 printk(KERN_DEBUG "release_dev: driver.termios[%d] not termios "
2417 if (tty->termios_locked != tty->driver->termios_locked[idx]) {
2418 printk(KERN_DEBUG "release_dev: driver.termios_locked[%d] not "
2419 "termios_locked for (%s)\n",
2426 #ifdef TTY_DEBUG_HANGUP
2427 printk(KERN_DEBUG "release_dev of %s (tty count=%d)...",
2428 tty_name(tty, buf), tty->count);
2431 #ifdef TTY_PARANOIA_CHECK
2432 if (tty->driver->other &&
2433 !(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
2434 if (o_tty != tty->driver->other->ttys[idx]) {
2435 printk(KERN_DEBUG "release_dev: other->table[%d] "
2436 "not o_tty for (%s)\n",
2440 if (o_tty->termios != tty->driver->other->termios[idx]) {
2441 printk(KERN_DEBUG "release_dev: other->termios[%d] "
2442 "not o_termios for (%s)\n",
2446 if (o_tty->termios_locked !=
2447 tty->driver->other->termios_locked[idx]) {
2448 printk(KERN_DEBUG "release_dev: other->termios_locked["
2449 "%d] not o_termios_locked for (%s)\n",
2453 if (o_tty->link != tty) {
2454 printk(KERN_DEBUG "release_dev: bad pty pointers\n");
2459 if (tty->driver->close)
2460 tty->driver->close(tty, filp);
2463 * Sanity check: if tty->count is going to zero, there shouldn't be
2464 * any waiters on tty->read_wait or tty->write_wait. We test the
2465 * wait queues and kick everyone out _before_ actually starting to
2466 * close. This ensures that we won't block while releasing the tty
2469 * The test for the o_tty closing is necessary, since the master and
2470 * slave sides may close in any order. If the slave side closes out
2471 * first, its count will be one, since the master side holds an open.
2472 * Thus this test wouldn't be triggered at the time the slave closes,
2475 * Note that it's possible for the tty to be opened again while we're
2476 * flushing out waiters. By recalculating the closing flags before
2477 * each iteration we avoid any problems.
2480 /* Guard against races with tty->count changes elsewhere and
2481 opens on /dev/tty */
2483 mutex_lock(&tty_mutex);
2484 tty_closing = tty->count <= 1;
2485 o_tty_closing = o_tty &&
2486 (o_tty->count <= (pty_master ? 1 : 0));
2490 if (waitqueue_active(&tty->read_wait)) {
2491 wake_up(&tty->read_wait);
2494 if (waitqueue_active(&tty->write_wait)) {
2495 wake_up(&tty->write_wait);
2499 if (o_tty_closing) {
2500 if (waitqueue_active(&o_tty->read_wait)) {
2501 wake_up(&o_tty->read_wait);
2504 if (waitqueue_active(&o_tty->write_wait)) {
2505 wake_up(&o_tty->write_wait);
2512 printk(KERN_WARNING "release_dev: %s: read/write wait queue "
2513 "active!\n", tty_name(tty, buf));
2514 mutex_unlock(&tty_mutex);
2519 * The closing flags are now consistent with the open counts on
2520 * both sides, and we've completed the last operation that could
2521 * block, so it's safe to proceed with closing.
2524 if (--o_tty->count < 0) {
2525 printk(KERN_WARNING "release_dev: bad pty slave count "
2527 o_tty->count, tty_name(o_tty, buf));
2531 if (--tty->count < 0) {
2532 printk(KERN_WARNING "release_dev: bad tty->count (%d) for %s\n",
2533 tty->count, tty_name(tty, buf));
2538 * We've decremented tty->count, so we need to remove this file
2539 * descriptor off the tty->tty_files list; this serves two
2541 * - check_tty_count sees the correct number of file descriptors
2542 * associated with this tty.
2543 * - do_tty_hangup no longer sees this file descriptor as
2544 * something that needs to be handled for hangups.
2547 filp->private_data = NULL;
2550 * Perform some housekeeping before deciding whether to return.
2552 * Set the TTY_CLOSING flag if this was the last open. In the
2553 * case of a pty we may have to wait around for the other side
2554 * to close, and TTY_CLOSING makes sure we can't be reopened.
2557 set_bit(TTY_CLOSING, &tty->flags);
2559 set_bit(TTY_CLOSING, &o_tty->flags);
2562 * If _either_ side is closing, make sure there aren't any
2563 * processes that still think tty or o_tty is their controlling
2566 if (tty_closing || o_tty_closing) {
2567 read_lock(&tasklist_lock);
2568 session_clear_tty(tty->session);
2570 session_clear_tty(o_tty->session);
2571 read_unlock(&tasklist_lock);
2574 mutex_unlock(&tty_mutex);
2576 /* check whether both sides are closing ... */
2577 if (!tty_closing || (o_tty && !o_tty_closing))
2580 #ifdef TTY_DEBUG_HANGUP
2581 printk(KERN_DEBUG "freeing tty structure...");
2584 * Prevent flush_to_ldisc() from rescheduling the work for later. Then
2585 * kill any delayed work. As this is the final close it does not
2586 * race with the set_ldisc code path.
2588 clear_bit(TTY_LDISC, &tty->flags);
2589 cancel_delayed_work(&tty->buf.work);
2592 * Wait for ->hangup_work and ->buf.work handlers to terminate
2595 flush_scheduled_work();
2598 * Wait for any short term users (we know they are just driver
2599 * side waiters as the file is closing so user count on the file
2602 spin_lock_irqsave(&tty_ldisc_lock, flags);
2603 while (tty->ldisc.refcount) {
2604 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
2605 wait_event(tty_ldisc_wait, tty->ldisc.refcount == 0);
2606 spin_lock_irqsave(&tty_ldisc_lock, flags);
2608 spin_unlock_irqrestore(&tty_ldisc_lock, flags);
2610 * Shutdown the current line discipline, and reset it to N_TTY.
2611 * N.B. why reset ldisc when we're releasing the memory??
2613 * FIXME: this MUST get fixed for the new reflocking
2615 if (tty->ldisc.close)
2616 (tty->ldisc.close)(tty);
2617 tty_ldisc_put(tty->ldisc.num);
2620 * Switch the line discipline back
2622 tty_ldisc_assign(tty, tty_ldisc_get(N_TTY));
2623 tty_set_termios_ldisc(tty, N_TTY);
2625 /* FIXME: could o_tty be in setldisc here ? */
2626 clear_bit(TTY_LDISC, &o_tty->flags);
2627 if (o_tty->ldisc.close)
2628 (o_tty->ldisc.close)(o_tty);
2629 tty_ldisc_put(o_tty->ldisc.num);
2630 tty_ldisc_assign(o_tty, tty_ldisc_get(N_TTY));
2631 tty_set_termios_ldisc(o_tty, N_TTY);
2634 * The release_tty function takes care of the details of clearing
2635 * the slots and preserving the termios structure.
2637 release_tty(tty, idx);
2639 #ifdef CONFIG_UNIX98_PTYS
2640 /* Make this pty number available for reallocation */
2642 mutex_lock(&allocated_ptys_lock);
2643 idr_remove(&allocated_ptys, idx);
2644 mutex_unlock(&allocated_ptys_lock);
2651 * tty_open - open a tty device
2652 * @inode: inode of device file
2653 * @filp: file pointer to tty
2655 * tty_open and tty_release keep up the tty count that contains the
2656 * number of opens done on a tty. We cannot use the inode-count, as
2657 * different inodes might point to the same tty.
2659 * Open-counting is needed for pty masters, as well as for keeping
2660 * track of serial lines: DTR is dropped when the last close happens.
2661 * (This is not done solely through tty->count, now. - Ted 1/27/92)
2663 * The termios state of a pty is reset on first open so that
2664 * settings don't persist across reuse.
2666 * Locking: tty_mutex protects tty, get_tty_driver and init_dev work.
2667 * tty->count should protect the rest.
2668 * ->siglock protects ->signal/->sighand
2671 static int tty_open(struct inode *inode, struct file *filp)
2673 struct tty_struct *tty;
2675 struct tty_driver *driver;
2677 dev_t device = inode->i_rdev;
2678 unsigned short saved_flags = filp->f_flags;
2680 nonseekable_open(inode, filp);
2683 noctty = filp->f_flags & O_NOCTTY;
2687 mutex_lock(&tty_mutex);
2689 if (device == MKDEV(TTYAUX_MAJOR, 0)) {
2690 tty = get_current_tty();
2692 mutex_unlock(&tty_mutex);
2695 driver = tty->driver;
2697 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
2702 if (device == MKDEV(TTY_MAJOR, 0)) {
2703 extern struct tty_driver *console_driver;
2704 driver = console_driver;
2710 if (device == MKDEV(TTYAUX_MAJOR, 1)) {
2711 driver = console_device(&index);
2713 /* Don't let /dev/console block */
2714 filp->f_flags |= O_NONBLOCK;
2718 mutex_unlock(&tty_mutex);
2722 driver = get_tty_driver(device, &index);
2724 mutex_unlock(&tty_mutex);
2728 retval = init_dev(driver, index, &tty);
2729 mutex_unlock(&tty_mutex);
2733 filp->private_data = tty;
2734 file_move(filp, &tty->tty_files);
2735 check_tty_count(tty, "tty_open");
2736 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2737 tty->driver->subtype == PTY_TYPE_MASTER)
2739 #ifdef TTY_DEBUG_HANGUP
2740 printk(KERN_DEBUG "opening %s...", tty->name);
2743 if (tty->driver->open)
2744 retval = tty->driver->open(tty, filp);
2748 filp->f_flags = saved_flags;
2750 if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) &&
2751 !capable(CAP_SYS_ADMIN))
2755 #ifdef TTY_DEBUG_HANGUP
2756 printk(KERN_DEBUG "error %d in opening %s...", retval,
2760 if (retval != -ERESTARTSYS)
2762 if (signal_pending(current))
2766 * Need to reset f_op in case a hangup happened.
2768 if (filp->f_op == &hung_up_tty_fops)
2769 filp->f_op = &tty_fops;
2773 mutex_lock(&tty_mutex);
2774 spin_lock_irq(¤t->sighand->siglock);
2776 current->signal->leader &&
2777 !current->signal->tty &&
2778 tty->session == NULL)
2779 __proc_set_tty(current, tty);
2780 spin_unlock_irq(¤t->sighand->siglock);
2781 mutex_unlock(&tty_mutex);
2785 #ifdef CONFIG_UNIX98_PTYS
2787 * ptmx_open - open a unix 98 pty master
2788 * @inode: inode of device file
2789 * @filp: file pointer to tty
2791 * Allocate a unix98 pty master device from the ptmx driver.
2793 * Locking: tty_mutex protects theinit_dev work. tty->count should
2795 * allocated_ptys_lock handles the list of free pty numbers
2798 static int ptmx_open(struct inode *inode, struct file *filp)
2800 struct tty_struct *tty;
2805 nonseekable_open(inode, filp);
2807 /* find a device that is not in use. */
2808 mutex_lock(&allocated_ptys_lock);
2809 if (!idr_pre_get(&allocated_ptys, GFP_KERNEL)) {
2810 mutex_unlock(&allocated_ptys_lock);
2813 idr_ret = idr_get_new(&allocated_ptys, NULL, &index);
2815 mutex_unlock(&allocated_ptys_lock);
2816 if (idr_ret == -EAGAIN)
2820 if (index >= pty_limit) {
2821 idr_remove(&allocated_ptys, index);
2822 mutex_unlock(&allocated_ptys_lock);
2825 mutex_unlock(&allocated_ptys_lock);
2827 mutex_lock(&tty_mutex);
2828 retval = init_dev(ptm_driver, index, &tty);
2829 mutex_unlock(&tty_mutex);
2834 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
2835 filp->private_data = tty;
2836 file_move(filp, &tty->tty_files);
2839 if (devpts_pty_new(tty->link))
2842 check_tty_count(tty, "tty_open");
2843 retval = ptm_driver->open(tty, filp);
2850 mutex_lock(&allocated_ptys_lock);
2851 idr_remove(&allocated_ptys, index);
2852 mutex_unlock(&allocated_ptys_lock);
2858 * tty_release - vfs callback for close
2859 * @inode: inode of tty
2860 * @filp: file pointer for handle to tty
2862 * Called the last time each file handle is closed that references
2863 * this tty. There may however be several such references.
2866 * Takes bkl. See release_dev
2869 static int tty_release(struct inode *inode, struct file *filp)
2878 * tty_poll - check tty status
2879 * @filp: file being polled
2880 * @wait: poll wait structures to update
2882 * Call the line discipline polling method to obtain the poll
2883 * status of the device.
2885 * Locking: locks called line discipline but ldisc poll method
2886 * may be re-entered freely by other callers.
2889 static unsigned int tty_poll(struct file *filp, poll_table *wait)
2891 struct tty_struct *tty;
2892 struct tty_ldisc *ld;
2895 tty = (struct tty_struct *)filp->private_data;
2896 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_poll"))
2899 ld = tty_ldisc_ref_wait(tty);
2901 ret = (ld->poll)(tty, filp, wait);
2902 tty_ldisc_deref(ld);
2906 static int tty_fasync(int fd, struct file *filp, int on)
2908 struct tty_struct *tty;
2909 unsigned long flags;
2912 tty = (struct tty_struct *)filp->private_data;
2913 if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_fasync"))
2916 retval = fasync_helper(fd, filp, on, &tty->fasync);
2923 if (!waitqueue_active(&tty->read_wait))
2924 tty->minimum_to_wake = 1;
2925 spin_lock_irqsave(&tty->ctrl_lock, flags);
2928 type = PIDTYPE_PGID;
2930 pid = task_pid(current);
2933 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2934 retval = __f_setown(filp, pid, type, 0);
2938 if (!tty->fasync && !waitqueue_active(&tty->read_wait))
2939 tty->minimum_to_wake = N_TTY_BUF_SIZE;
2945 * tiocsti - fake input character
2946 * @tty: tty to fake input into
2947 * @p: pointer to character
2949 * Fake input to a tty device. Does the necessary locking and
2952 * FIXME: does not honour flow control ??
2955 * Called functions take tty_ldisc_lock
2956 * current->signal->tty check is safe without locks
2958 * FIXME: may race normal receive processing
2961 static int tiocsti(struct tty_struct *tty, char __user *p)
2964 struct tty_ldisc *ld;
2966 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2968 if (get_user(ch, p))
2970 ld = tty_ldisc_ref_wait(tty);
2971 ld->receive_buf(tty, &ch, &mbz, 1);
2972 tty_ldisc_deref(ld);
2977 * tiocgwinsz - implement window query ioctl
2979 * @arg: user buffer for result
2981 * Copies the kernel idea of the window size into the user buffer.
2983 * Locking: tty->termios_mutex is taken to ensure the winsize data
2987 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2991 mutex_lock(&tty->termios_mutex);
2992 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2993 mutex_unlock(&tty->termios_mutex);
2995 return err ? -EFAULT: 0;
2999 * tiocswinsz - implement window size set ioctl
3001 * @arg: user buffer for result
3003 * Copies the user idea of the window size to the kernel. Traditionally
3004 * this is just advisory information but for the Linux console it
3005 * actually has driver level meaning and triggers a VC resize.
3008 * Called function use the console_sem is used to ensure we do
3009 * not try and resize the console twice at once.
3010 * The tty->termios_mutex is used to ensure we don't double
3011 * resize and get confused. Lock order - tty->termios_mutex before
3015 static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty,
3016 struct winsize __user *arg)
3018 struct winsize tmp_ws;
3019 struct pid *pgrp, *rpgrp;
3020 unsigned long flags;
3022 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
3025 mutex_lock(&tty->termios_mutex);
3026 if (!memcmp(&tmp_ws, &tty->winsize, sizeof(*arg)))
3030 if (tty->driver->type == TTY_DRIVER_TYPE_CONSOLE) {
3031 if (vc_lock_resize(tty->driver_data, tmp_ws.ws_col,
3033 mutex_unlock(&tty->termios_mutex);
3038 /* Get the PID values and reference them so we can
3039 avoid holding the tty ctrl lock while sending signals */
3040 spin_lock_irqsave(&tty->ctrl_lock, flags);
3041 pgrp = get_pid(tty->pgrp);
3042 rpgrp = get_pid(real_tty->pgrp);
3043 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
3046 kill_pgrp(pgrp, SIGWINCH, 1);
3047 if (rpgrp != pgrp && rpgrp)
3048 kill_pgrp(rpgrp, SIGWINCH, 1);
3053 tty->winsize = tmp_ws;
3054 real_tty->winsize = tmp_ws;
3056 mutex_unlock(&tty->termios_mutex);
3061 * tioccons - allow admin to move logical console
3062 * @file: the file to become console
3064 * Allow the adminstrator to move the redirected console device
3066 * Locking: uses redirect_lock to guard the redirect information
3069 static int tioccons(struct file *file)
3071 if (!capable(CAP_SYS_ADMIN))
3073 if (file->f_op->write == redirected_tty_write) {
3075 spin_lock(&redirect_lock);
3078 spin_unlock(&redirect_lock);
3083 spin_lock(&redirect_lock);
3085 spin_unlock(&redirect_lock);
3090 spin_unlock(&redirect_lock);
3095 * fionbio - non blocking ioctl
3096 * @file: file to set blocking value
3097 * @p: user parameter
3099 * Historical tty interfaces had a blocking control ioctl before
3100 * the generic functionality existed. This piece of history is preserved
3101 * in the expected tty API of posix OS's.
3103 * Locking: none, the open fle handle ensures it won't go away.
3106 static int fionbio(struct file *file, int __user *p)
3110 if (get_user(nonblock, p))
3113 /* file->f_flags is still BKL protected in the fs layer - vomit */
3116 file->f_flags |= O_NONBLOCK;
3118 file->f_flags &= ~O_NONBLOCK;
3124 * tiocsctty - set controlling tty
3125 * @tty: tty structure
3126 * @arg: user argument
3128 * This ioctl is used to manage job control. It permits a session
3129 * leader to set this tty as the controlling tty for the session.
3132 * Takes tty_mutex() to protect tty instance
3133 * Takes tasklist_lock internally to walk sessions
3134 * Takes ->siglock() when updating signal->tty
3137 static int tiocsctty(struct tty_struct *tty, int arg)
3140 if (current->signal->leader && (task_session(current) == tty->session))
3143 mutex_lock(&tty_mutex);
3145 * The process must be a session leader and
3146 * not have a controlling tty already.
3148 if (!current->signal->leader || current->signal->tty) {
3155 * This tty is already the controlling
3156 * tty for another session group!
3158 if (arg == 1 && capable(CAP_SYS_ADMIN)) {
3162 read_lock(&tasklist_lock);
3163 session_clear_tty(tty->session);
3164 read_unlock(&tasklist_lock);
3170 proc_set_tty(current, tty);
3172 mutex_unlock(&tty_mutex);
3177 * tty_get_pgrp - return a ref counted pgrp pid
3180 * Returns a refcounted instance of the pid struct for the process
3181 * group controlling the tty.
3184 struct pid *tty_get_pgrp(struct tty_struct *tty)
3186 unsigned long flags;
3189 spin_lock_irqsave(&tty->ctrl_lock, flags);
3190 pgrp = get_pid(tty->pgrp);
3191 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
3195 EXPORT_SYMBOL_GPL(tty_get_pgrp);
3198 * tiocgpgrp - get process group
3199 * @tty: tty passed by user
3200 * @real_tty: tty side of the tty pased by the user if a pty else the tty
3203 * Obtain the process group of the tty. If there is no process group
3206 * Locking: none. Reference to current->signal->tty is safe.
3209 static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
3214 * (tty == real_tty) is a cheap way of
3215 * testing if the tty is NOT a master pty.
3217 if (tty == real_tty && current->signal->tty != real_tty)
3219 pid = tty_get_pgrp(real_tty);
3220 ret = put_user(pid_vnr(pid), p);
3226 * tiocspgrp - attempt to set process group
3227 * @tty: tty passed by user
3228 * @real_tty: tty side device matching tty passed by user
3231 * Set the process group of the tty to the session passed. Only
3232 * permitted where the tty session is our session.
3234 * Locking: RCU, ctrl lock
3237 static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
3241 int retval = tty_check_change(real_tty);
3242 unsigned long flags;
3248 if (!current->signal->tty ||
3249 (current->signal->tty != real_tty) ||
3250 (real_tty->session != task_session(current)))
3252 if (get_user(pgrp_nr, p))
3257 pgrp = find_vpid(pgrp_nr);
3262 if (session_of_pgrp(pgrp) != task_session(current))
3265 spin_lock_irqsave(&tty->ctrl_lock, flags);
3266 put_pid(real_tty->pgrp);
3267 real_tty->pgrp = get_pid(pgrp);
3268 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
3275 * tiocgsid - get session id
3276 * @tty: tty passed by user
3277 * @real_tty: tty side of the tty pased by the user if a pty else the tty
3278 * @p: pointer to returned session id
3280 * Obtain the session id of the tty. If there is no session
3283 * Locking: none. Reference to current->signal->tty is safe.
3286 static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
3289 * (tty == real_tty) is a cheap way of
3290 * testing if the tty is NOT a master pty.
3292 if (tty == real_tty && current->signal->tty != real_tty)
3294 if (!real_tty->session)
3296 return put_user(pid_vnr(real_tty->session), p);
3300 * tiocsetd - set line discipline
3302 * @p: pointer to user data
3304 * Set the line discipline according to user request.
3306 * Locking: see tty_set_ldisc, this function is just a helper
3309 static int tiocsetd(struct tty_struct *tty, int __user *p)
3314 if (get_user(ldisc, p))
3318 ret = tty_set_ldisc(tty, ldisc);
3325 * send_break - performed time break
3326 * @tty: device to break on
3327 * @duration: timeout in mS
3329 * Perform a timed break on hardware that lacks its own driver level
3330 * timed break functionality.
3333 * atomic_write_lock serializes
3337 static int send_break(struct tty_struct *tty, unsigned int duration)
3339 int retval = -EINTR;
3342 if (tty_write_lock(tty, 0) < 0)
3344 tty->driver->break_ctl(tty, -1);
3345 if (!signal_pending(current))
3346 msleep_interruptible(duration);
3347 tty->driver->break_ctl(tty, 0);
3348 tty_write_unlock(tty);
3349 if (!signal_pending(current))
3357 * tiocmget - get modem status
3359 * @file: user file pointer
3360 * @p: pointer to result
3362 * Obtain the modem status bits from the tty driver if the feature
3363 * is supported. Return -EINVAL if it is not available.
3365 * Locking: none (up to the driver)
3368 static int tty_tiocmget(struct tty_struct *tty, struct file *file, int __user *p)
3370 int retval = -EINVAL;
3372 if (tty->driver->tiocmget) {
3374 retval = tty->driver->tiocmget(tty, file);
3378 retval = put_user(retval, p);
3384 * tiocmset - set modem status
3386 * @file: user file pointer
3387 * @cmd: command - clear bits, set bits or set all
3388 * @p: pointer to desired bits
3390 * Set the modem status bits from the tty driver if the feature
3391 * is supported. Return -EINVAL if it is not available.
3393 * Locking: none (up to the driver)
3396 static int tty_tiocmset(struct tty_struct *tty, struct file *file, unsigned int cmd,
3399 int retval = -EINVAL;
3401 if (tty->driver->tiocmset) {
3402 unsigned int set, clear, val;
3404 retval = get_user(val, p);
3422 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
3423 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
3426 retval = tty->driver->tiocmset(tty, file, set, clear);
3433 * Split this up, as gcc can choke on it otherwise..
3435 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
3437 struct tty_struct *tty, *real_tty;
3438 void __user *p = (void __user *)arg;
3440 struct tty_ldisc *ld;
3441 struct inode *inode = file->f_dentry->d_inode;
3443 tty = (struct tty_struct *)file->private_data;
3444 if (tty_paranoia_check(tty, inode, "tty_ioctl"))
3448 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
3449 tty->driver->subtype == PTY_TYPE_MASTER)
3450 real_tty = tty->link;
3453 * Break handling by driver
3458 if (!tty->driver->break_ctl) {
3462 if (tty->driver->ioctl)
3463 retval = tty->driver->ioctl(tty, file, cmd, arg);
3466 /* These two ioctl's always return success; even if */
3467 /* the driver doesn't support them. */
3470 if (!tty->driver->ioctl)
3473 retval = tty->driver->ioctl(tty, file, cmd, arg);
3475 if (retval == -ENOIOCTLCMD)
3482 * Factor out some common prep work
3490 retval = tty_check_change(tty);
3493 if (cmd != TIOCCBRK) {
3495 tty_wait_until_sent(tty, 0);
3497 if (signal_pending(current))
3505 return tiocsti(tty, p);
3507 return tiocgwinsz(tty, p);
3509 return tiocswinsz(tty, real_tty, p);
3511 return real_tty != tty ? -EINVAL : tioccons(file);
3513 return fionbio(file, p);
3515 set_bit(TTY_EXCLUSIVE, &tty->flags);
3518 clear_bit(TTY_EXCLUSIVE, &tty->flags);
3521 if (current->signal->tty != tty)
3526 return tiocsctty(tty, arg);
3528 return tiocgpgrp(tty, real_tty, p);
3530 return tiocspgrp(tty, real_tty, p);
3532 return tiocgsid(tty, real_tty, p);
3534 /* FIXME: check this is ok */
3535 return put_user(tty->ldisc.num, (int __user *)p);
3537 return tiocsetd(tty, p);
3540 return tioclinux(tty, arg);
3545 case TIOCSBRK: /* Turn break on, unconditionally */
3547 tty->driver->break_ctl(tty, -1);
3551 case TIOCCBRK: /* Turn break off, unconditionally */
3553 tty->driver->break_ctl(tty, 0);
3556 case TCSBRK: /* SVID version: non-zero arg --> no break */
3557 /* non-zero arg means wait for all output data
3558 * to be sent (performed above) but don't send break.
3559 * This is used by the tcdrain() termios function.
3562 return send_break(tty, 250);
3564 case TCSBRKP: /* support for POSIX tcsendbreak() */
3565 return send_break(tty, arg ? arg*100 : 250);
3568 return tty_tiocmget(tty, file, p);
3572 return tty_tiocmset(tty, file, cmd, p);
3577 /* flush tty buffer and allow ldisc to process ioctl */
3578 tty_buffer_flush(tty);
3583 if (tty->driver->ioctl) {
3584 retval = (tty->driver->ioctl)(tty, file, cmd, arg);
3585 if (retval != -ENOIOCTLCMD)
3588 ld = tty_ldisc_ref_wait(tty);
3591 retval = ld->ioctl(tty, file, cmd, arg);
3592 if (retval == -ENOIOCTLCMD)
3595 tty_ldisc_deref(ld);
3599 #ifdef CONFIG_COMPAT
3600 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
3603 struct inode *inode = file->f_dentry->d_inode;
3604 struct tty_struct *tty = file->private_data;
3605 struct tty_ldisc *ld;
3606 int retval = -ENOIOCTLCMD;
3608 if (tty_paranoia_check(tty, inode, "tty_ioctl"))
3611 if (tty->driver->compat_ioctl) {
3612 retval = (tty->driver->compat_ioctl)(tty, file, cmd, arg);
3613 if (retval != -ENOIOCTLCMD)
3617 ld = tty_ldisc_ref_wait(tty);
3618 if (ld->compat_ioctl)
3619 retval = ld->compat_ioctl(tty, file, cmd, arg);
3620 tty_ldisc_deref(ld);
3627 * This implements the "Secure Attention Key" --- the idea is to
3628 * prevent trojan horses by killing all processes associated with this
3629 * tty when the user hits the "Secure Attention Key". Required for
3630 * super-paranoid applications --- see the Orange Book for more details.
3632 * This code could be nicer; ideally it should send a HUP, wait a few
3633 * seconds, then send a INT, and then a KILL signal. But you then
3634 * have to coordinate with the init process, since all processes associated
3635 * with the current tty must be dead before the new getty is allowed
3638 * Now, if it would be correct ;-/ The current code has a nasty hole -
3639 * it doesn't catch files in flight. We may send the descriptor to ourselves
3640 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
3642 * Nasty bug: do_SAK is being called in interrupt context. This can
3643 * deadlock. We punt it up to process context. AKPM - 16Mar2001
3645 void __do_SAK(struct tty_struct *tty)
3650 struct task_struct *g, *p;
3651 struct pid *session;
3654 struct fdtable *fdt;
3658 session = tty->session;
3660 tty_ldisc_flush(tty);
3662 if (tty->driver->flush_buffer)
3663 tty->driver->flush_buffer(tty);
3665 read_lock(&tasklist_lock);
3666 /* Kill the entire session */
3667 do_each_pid_task(session, PIDTYPE_SID, p) {
3668 printk(KERN_NOTICE "SAK: killed process %d"
3669 " (%s): task_session_nr(p)==tty->session\n",
3670 task_pid_nr(p), p->comm);
3671 send_sig(SIGKILL, p, 1);
3672 } while_each_pid_task(session, PIDTYPE_SID, p);
3673 /* Now kill any processes that happen to have the
3676 do_each_thread(g, p) {
3677 if (p->signal->tty == tty) {
3678 printk(KERN_NOTICE "SAK: killed process %d"
3679 " (%s): task_session_nr(p)==tty->session\n",
3680 task_pid_nr(p), p->comm);
3681 send_sig(SIGKILL, p, 1);
3687 * We don't take a ref to the file, so we must
3688 * hold ->file_lock instead.
3690 spin_lock(&p->files->file_lock);
3691 fdt = files_fdtable(p->files);
3692 for (i = 0; i < fdt->max_fds; i++) {
3693 filp = fcheck_files(p->files, i);
3696 if (filp->f_op->read == tty_read &&
3697 filp->private_data == tty) {
3698 printk(KERN_NOTICE "SAK: killed process %d"
3699 " (%s): fd#%d opened to the tty\n",
3700 task_pid_nr(p), p->comm, i);
3701 force_sig(SIGKILL, p);
3705 spin_unlock(&p->files->file_lock);
3708 } while_each_thread(g, p);
3709 read_unlock(&tasklist_lock);
3713 static void do_SAK_work(struct work_struct *work)
3715 struct tty_struct *tty =
3716 container_of(work, struct tty_struct, SAK_work);
3721 * The tq handling here is a little racy - tty->SAK_work may already be queued.
3722 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
3723 * the values which we write to it will be identical to the values which it
3724 * already has. --akpm
3726 void do_SAK(struct tty_struct *tty)
3730 schedule_work(&tty->SAK_work);
3733 EXPORT_SYMBOL(do_SAK);
3737 * @work: tty structure passed from work queue.
3739 * This routine is called out of the software interrupt to flush data
3740 * from the buffer chain to the line discipline.
3742 * Locking: holds tty->buf.lock to guard buffer list. Drops the lock
3743 * while invoking the line discipline receive_buf method. The
3744 * receive_buf method is single threaded for each tty instance.
3747 static void flush_to_ldisc(struct work_struct *work)
3749 struct tty_struct *tty =
3750 container_of(work, struct tty_struct, buf.work.work);
3751 unsigned long flags;
3752 struct tty_ldisc *disc;
3753 struct tty_buffer *tbuf, *head;
3755 unsigned char *flag_buf;
3757 disc = tty_ldisc_ref(tty);
3758 if (disc == NULL) /* !TTY_LDISC */
3761 spin_lock_irqsave(&tty->buf.lock, flags);
3762 /* So we know a flush is running */
3763 set_bit(TTY_FLUSHING, &tty->flags);
3764 head = tty->buf.head;
3766 tty->buf.head = NULL;
3768 int count = head->commit - head->read;
3770 if (head->next == NULL)
3774 tty_buffer_free(tty, tbuf);
3777 /* Ldisc or user is trying to flush the buffers
3778 we are feeding to the ldisc, stop feeding the
3779 line discipline as we want to empty the queue */
3780 if (test_bit(TTY_FLUSHPENDING, &tty->flags))
3782 if (!tty->receive_room) {
3783 schedule_delayed_work(&tty->buf.work, 1);
3786 if (count > tty->receive_room)
3787 count = tty->receive_room;
3788 char_buf = head->char_buf_ptr + head->read;
3789 flag_buf = head->flag_buf_ptr + head->read;
3790 head->read += count;
3791 spin_unlock_irqrestore(&tty->buf.lock, flags);
3792 disc->receive_buf(tty, char_buf, flag_buf, count);
3793 spin_lock_irqsave(&tty->buf.lock, flags);
3795 /* Restore the queue head */
3796 tty->buf.head = head;
3798 /* We may have a deferred request to flush the input buffer,
3799 if so pull the chain under the lock and empty the queue */
3800 if (test_bit(TTY_FLUSHPENDING, &tty->flags)) {
3801 __tty_buffer_flush(tty);
3802 clear_bit(TTY_FLUSHPENDING, &tty->flags);
3803 wake_up(&tty->read_wait);
3805 clear_bit(TTY_FLUSHING, &tty->flags);
3806 spin_unlock_irqrestore(&tty->buf.lock, flags);
3808 tty_ldisc_deref(disc);
3812 * tty_flip_buffer_push - terminal
3815 * Queue a push of the terminal flip buffers to the line discipline. This
3816 * function must not be called from IRQ context if tty->low_latency is set.
3818 * In the event of the queue being busy for flipping the work will be
3819 * held off and retried later.
3821 * Locking: tty buffer lock. Driver locks in low latency mode.
3824 void tty_flip_buffer_push(struct tty_struct *tty)
3826 unsigned long flags;
3827 spin_lock_irqsave(&tty->buf.lock, flags);
3828 if (tty->buf.tail != NULL)
3829 tty->buf.tail->commit = tty->buf.tail->used;
3830 spin_unlock_irqrestore(&tty->buf.lock, flags);
3832 if (tty->low_latency)
3833 flush_to_ldisc(&tty->buf.work.work);
3835 schedule_delayed_work(&tty->buf.work, 1);
3838 EXPORT_SYMBOL(tty_flip_buffer_push);
3842 * initialize_tty_struct
3843 * @tty: tty to initialize
3845 * This subroutine initializes a tty structure that has been newly
3848 * Locking: none - tty in question must not be exposed at this point
3851 static void initialize_tty_struct(struct tty_struct *tty)
3853 memset(tty, 0, sizeof(struct tty_struct));
3854 tty->magic = TTY_MAGIC;
3855 tty_ldisc_assign(tty, tty_ldisc_get(N_TTY));
3856 tty->session = NULL;
3858 tty->overrun_time = jiffies;
3859 tty->buf.head = tty->buf.tail = NULL;
3860 tty_buffer_init(tty);
3861 INIT_DELAYED_WORK(&tty->buf.work, flush_to_ldisc);
3862 mutex_init(&tty->termios_mutex);
3863 init_waitqueue_head(&tty->write_wait);
3864 init_waitqueue_head(&tty->read_wait);
3865 INIT_WORK(&tty->hangup_work, do_tty_hangup);
3866 mutex_init(&tty->atomic_read_lock);
3867 mutex_init(&tty->atomic_write_lock);
3868 spin_lock_init(&tty->read_lock);
3869 spin_lock_init(&tty->ctrl_lock);
3870 INIT_LIST_HEAD(&tty->tty_files);
3871 INIT_WORK(&tty->SAK_work, do_SAK_work);
3875 * The default put_char routine if the driver did not define one.
3878 static void tty_default_put_char(struct tty_struct *tty, unsigned char ch)
3880 tty->driver->write(tty, &ch, 1);
3883 static struct class *tty_class;
3886 * tty_register_device - register a tty device
3887 * @driver: the tty driver that describes the tty device
3888 * @index: the index in the tty driver for this tty device
3889 * @device: a struct device that is associated with this tty device.
3890 * This field is optional, if there is no known struct device
3891 * for this tty device it can be set to NULL safely.
3893 * Returns a pointer to the struct device for this tty device
3894 * (or ERR_PTR(-EFOO) on error).
3896 * This call is required to be made to register an individual tty device
3897 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3898 * that bit is not set, this function should not be called by a tty
3904 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
3905 struct device *device)
3908 dev_t dev = MKDEV(driver->major, driver->minor_start) + index;
3910 if (index >= driver->num) {
3911 printk(KERN_ERR "Attempt to register invalid tty line number "
3913 return ERR_PTR(-EINVAL);
3916 if (driver->type == TTY_DRIVER_TYPE_PTY)
3917 pty_line_name(driver, index, name);
3919 tty_line_name(driver, index, name);
3921 return device_create(tty_class, device, dev, name);
3925 * tty_unregister_device - unregister a tty device
3926 * @driver: the tty driver that describes the tty device
3927 * @index: the index in the tty driver for this tty device
3929 * If a tty device is registered with a call to tty_register_device() then
3930 * this function must be called when the tty device is gone.
3935 void tty_unregister_device(struct tty_driver *driver, unsigned index)
3937 device_destroy(tty_class,
3938 MKDEV(driver->major, driver->minor_start) + index);
3941 EXPORT_SYMBOL(tty_register_device);
3942 EXPORT_SYMBOL(tty_unregister_device);
3944 struct tty_driver *alloc_tty_driver(int lines)
3946 struct tty_driver *driver;
3948 driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
3950 driver->magic = TTY_DRIVER_MAGIC;
3951 driver->num = lines;
3952 /* later we'll move allocation of tables here */
3957 void put_tty_driver(struct tty_driver *driver)
3962 void tty_set_operations(struct tty_driver *driver,
3963 const struct tty_operations *op)
3965 driver->open = op->open;
3966 driver->close = op->close;
3967 driver->write = op->write;
3968 driver->put_char = op->put_char;
3969 driver->flush_chars = op->flush_chars;
3970 driver->write_room = op->write_room;
3971 driver->chars_in_buffer = op->chars_in_buffer;
3972 driver->ioctl = op->ioctl;
3973 driver->compat_ioctl = op->compat_ioctl;
3974 driver->set_termios = op->set_termios;
3975 driver->throttle = op->throttle;
3976 driver->unthrottle = op->unthrottle;
3977 driver->stop = op->stop;
3978 driver->start = op->start;
3979 driver->hangup = op->hangup;
3980 driver->break_ctl = op->break_ctl;
3981 driver->flush_buffer = op->flush_buffer;
3982 driver->set_ldisc = op->set_ldisc;
3983 driver->wait_until_sent = op->wait_until_sent;
3984 driver->send_xchar = op->send_xchar;
3985 driver->read_proc = op->read_proc;
3986 driver->write_proc = op->write_proc;
3987 driver->tiocmget = op->tiocmget;
3988 driver->tiocmset = op->tiocmset;
3989 #ifdef CONFIG_CONSOLE_POLL
3990 driver->poll_init = op->poll_init;
3991 driver->poll_get_char = op->poll_get_char;
3992 driver->poll_put_char = op->poll_put_char;
3997 EXPORT_SYMBOL(alloc_tty_driver);
3998 EXPORT_SYMBOL(put_tty_driver);
3999 EXPORT_SYMBOL(tty_set_operations);
4002 * Called by a tty driver to register itself.
4004 int tty_register_driver(struct tty_driver *driver)
4011 if (driver->flags & TTY_DRIVER_INSTALLED)
4014 if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM) && driver->num) {
4015 p = kzalloc(driver->num * 3 * sizeof(void *), GFP_KERNEL);
4020 if (!driver->major) {
4021 error = alloc_chrdev_region(&dev, driver->minor_start,
4022 driver->num, driver->name);
4024 driver->major = MAJOR(dev);
4025 driver->minor_start = MINOR(dev);
4028 dev = MKDEV(driver->major, driver->minor_start);
4029 error = register_chrdev_region(dev, driver->num, driver->name);
4037 driver->ttys = (struct tty_struct **)p;
4038 driver->termios = (struct ktermios **)(p + driver->num);
4039 driver->termios_locked = (struct ktermios **)
4040 (p + driver->num * 2);
4042 driver->ttys = NULL;
4043 driver->termios = NULL;
4044 driver->termios_locked = NULL;
4047 cdev_init(&driver->cdev, &tty_fops);
4048 driver->cdev.owner = driver->owner;
4049 error = cdev_add(&driver->cdev, dev, driver->num);
4051 unregister_chrdev_region(dev, driver->num);
4052 driver->ttys = NULL;
4053 driver->termios = driver->termios_locked = NULL;
4058 if (!driver->put_char)
4059 driver->put_char = tty_default_put_char;
4061 mutex_lock(&tty_mutex);
4062 list_add(&driver->tty_drivers, &tty_drivers);
4063 mutex_unlock(&tty_mutex);
4065 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
4066 for (i = 0; i < driver->num; i++)
4067 tty_register_device(driver, i, NULL);
4069 proc_tty_register_driver(driver);
4073 EXPORT_SYMBOL(tty_register_driver);
4076 * Called by a tty driver to unregister itself.
4078 int tty_unregister_driver(struct tty_driver *driver)
4081 struct ktermios *tp;
4084 if (driver->refcount)
4087 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
4089 mutex_lock(&tty_mutex);
4090 list_del(&driver->tty_drivers);
4091 mutex_unlock(&tty_mutex);
4094 * Free the termios and termios_locked structures because
4095 * we don't want to get memory leaks when modular tty
4096 * drivers are removed from the kernel.
4098 for (i = 0; i < driver->num; i++) {
4099 tp = driver->termios[i];
4101 driver->termios[i] = NULL;
4104 tp = driver->termios_locked[i];
4106 driver->termios_locked[i] = NULL;
4109 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
4110 tty_unregister_device(driver, i);
4113 proc_tty_unregister_driver(driver);
4114 driver->ttys = NULL;
4115 driver->termios = driver->termios_locked = NULL;
4117 cdev_del(&driver->cdev);
4120 EXPORT_SYMBOL(tty_unregister_driver);
4122 dev_t tty_devnum(struct tty_struct *tty)
4124 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
4126 EXPORT_SYMBOL(tty_devnum);
4128 void proc_clear_tty(struct task_struct *p)
4130 spin_lock_irq(&p->sighand->siglock);
4131 p->signal->tty = NULL;
4132 spin_unlock_irq(&p->sighand->siglock);
4134 EXPORT_SYMBOL(proc_clear_tty);
4136 /* Called under the sighand lock */
4138 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
4141 unsigned long flags;
4142 /* We should not have a session or pgrp to put here but.... */
4143 spin_lock_irqsave(&tty->ctrl_lock, flags);
4144 put_pid(tty->session);
4146 tty->pgrp = get_pid(task_pgrp(tsk));
4147 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
4148 tty->session = get_pid(task_session(tsk));
4150 put_pid(tsk->signal->tty_old_pgrp);
4151 tsk->signal->tty = tty;
4152 tsk->signal->tty_old_pgrp = NULL;
4155 static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
4157 spin_lock_irq(&tsk->sighand->siglock);
4158 __proc_set_tty(tsk, tty);
4159 spin_unlock_irq(&tsk->sighand->siglock);
4162 struct tty_struct *get_current_tty(void)
4164 struct tty_struct *tty;
4165 WARN_ON_ONCE(!mutex_is_locked(&tty_mutex));
4166 tty = current->signal->tty;
4168 * session->tty can be changed/cleared from under us, make sure we
4169 * issue the load. The obtained pointer, when not NULL, is valid as
4170 * long as we hold tty_mutex.
4175 EXPORT_SYMBOL_GPL(get_current_tty);
4178 * Initialize the console device. This is called *early*, so
4179 * we can't necessarily depend on lots of kernel help here.
4180 * Just do some early initializations, and do the complex setup
4183 void __init console_init(void)
4187 /* Setup the default TTY line discipline. */
4188 (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY);
4191 * set up the console device so that later boot sequences can
4192 * inform about problems etc..
4194 call = __con_initcall_start;
4195 while (call < __con_initcall_end) {
4201 static int __init tty_class_init(void)
4203 tty_class = class_create(THIS_MODULE, "tty");
4204 if (IS_ERR(tty_class))
4205 return PTR_ERR(tty_class);
4209 postcore_initcall(tty_class_init);
4211 /* 3/2004 jmc: why do these devices exist? */
4213 static struct cdev tty_cdev, console_cdev;
4214 #ifdef CONFIG_UNIX98_PTYS
4215 static struct cdev ptmx_cdev;
4218 static struct cdev vc0_cdev;
4222 * Ok, now we can initialize the rest of the tty devices and can count
4223 * on memory allocations, interrupts etc..
4225 static int __init tty_init(void)
4227 cdev_init(&tty_cdev, &tty_fops);
4228 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
4229 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
4230 panic("Couldn't register /dev/tty driver\n");
4231 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), "tty");
4233 cdev_init(&console_cdev, &console_fops);
4234 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
4235 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
4236 panic("Couldn't register /dev/console driver\n");
4237 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 1), "console");
4239 #ifdef CONFIG_UNIX98_PTYS
4240 cdev_init(&ptmx_cdev, &ptmx_fops);
4241 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
4242 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
4243 panic("Couldn't register /dev/ptmx driver\n");
4244 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), "ptmx");
4248 cdev_init(&vc0_cdev, &console_fops);
4249 if (cdev_add(&vc0_cdev, MKDEV(TTY_MAJOR, 0), 1) ||
4250 register_chrdev_region(MKDEV(TTY_MAJOR, 0), 1, "/dev/vc/0") < 0)
4251 panic("Couldn't register /dev/tty0 driver\n");
4252 device_create(tty_class, NULL, MKDEV(TTY_MAJOR, 0), "tty0");
4258 module_init(tty_init);