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 int tty_ioctl(struct inode
*inode
, struct file
*file
,
156 unsigned int cmd
, unsigned long arg
);
158 static long tty_compat_ioctl(struct file
*file
, unsigned int cmd
,
161 #define tty_compat_ioctl NULL
163 static int tty_fasync(int fd
, struct file
*filp
, int on
);
164 static void release_tty(struct tty_struct
*tty
, int idx
);
165 static void __proc_set_tty(struct task_struct
*tsk
, struct tty_struct
*tty
);
166 static void proc_set_tty(struct task_struct
*tsk
, struct tty_struct
*tty
);
169 * alloc_tty_struct - allocate a tty object
171 * Return a new empty tty structure. The data fields have not
172 * been initialized in any way but has been zeroed
177 static struct tty_struct
*alloc_tty_struct(void)
179 return kzalloc(sizeof(struct tty_struct
), GFP_KERNEL
);
182 static void tty_buffer_free_all(struct tty_struct
*);
185 * free_tty_struct - free a disused tty
186 * @tty: tty struct to free
188 * Free the write buffers, tty queue and tty memory itself.
190 * Locking: none. Must be called after tty is definitely unused
193 static inline void free_tty_struct(struct tty_struct
*tty
)
195 kfree(tty
->write_buf
);
196 tty_buffer_free_all(tty
);
200 #define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base)
203 * tty_name - return tty naming
204 * @tty: tty structure
205 * @buf: buffer for output
207 * Convert a tty structure into a name. The name reflects the kernel
208 * naming policy and if udev is in use may not reflect user space
213 char *tty_name(struct tty_struct
*tty
, char *buf
)
215 if (!tty
) /* Hmm. NULL pointer. That's fun. */
216 strcpy(buf
, "NULL tty");
218 strcpy(buf
, tty
->name
);
222 EXPORT_SYMBOL(tty_name
);
224 int tty_paranoia_check(struct tty_struct
*tty
, struct inode
*inode
,
227 #ifdef TTY_PARANOIA_CHECK
230 "null TTY for (%d:%d) in %s\n",
231 imajor(inode
), iminor(inode
), routine
);
234 if (tty
->magic
!= TTY_MAGIC
) {
236 "bad magic number for tty struct (%d:%d) in %s\n",
237 imajor(inode
), iminor(inode
), routine
);
244 static int check_tty_count(struct tty_struct
*tty
, const char *routine
)
246 #ifdef CHECK_TTY_COUNT
251 list_for_each(p
, &tty
->tty_files
) {
255 if (tty
->driver
->type
== TTY_DRIVER_TYPE_PTY
&&
256 tty
->driver
->subtype
== PTY_TYPE_SLAVE
&&
257 tty
->link
&& tty
->link
->count
)
259 if (tty
->count
!= count
) {
260 printk(KERN_WARNING
"Warning: dev (%s) tty->count(%d) "
261 "!= #fd's(%d) in %s\n",
262 tty
->name
, tty
->count
, count
, routine
);
270 * Tty buffer allocation management
274 * tty_buffer_free_all - free buffers used by a tty
275 * @tty: tty to free from
277 * Remove all the buffers pending on a tty whether queued with data
278 * or in the free ring. Must be called when the tty is no longer in use
283 static void tty_buffer_free_all(struct tty_struct
*tty
)
285 struct tty_buffer
*thead
;
286 while ((thead
= tty
->buf
.head
) != NULL
) {
287 tty
->buf
.head
= thead
->next
;
290 while ((thead
= tty
->buf
.free
) != NULL
) {
291 tty
->buf
.free
= thead
->next
;
294 tty
->buf
.tail
= NULL
;
295 tty
->buf
.memory_used
= 0;
299 * tty_buffer_init - prepare a tty buffer structure
300 * @tty: tty to initialise
302 * Set up the initial state of the buffer management for a tty device.
303 * Must be called before the other tty buffer functions are used.
308 static void tty_buffer_init(struct tty_struct
*tty
)
310 spin_lock_init(&tty
->buf
.lock
);
311 tty
->buf
.head
= NULL
;
312 tty
->buf
.tail
= NULL
;
313 tty
->buf
.free
= NULL
;
314 tty
->buf
.memory_used
= 0;
318 * tty_buffer_alloc - allocate a tty buffer
320 * @size: desired size (characters)
322 * Allocate a new tty buffer to hold the desired number of characters.
323 * Return NULL if out of memory or the allocation would exceed the
326 * Locking: Caller must hold tty->buf.lock
329 static struct tty_buffer
*tty_buffer_alloc(struct tty_struct
*tty
, size_t size
)
331 struct tty_buffer
*p
;
333 if (tty
->buf
.memory_used
+ size
> 65536)
335 p
= kmalloc(sizeof(struct tty_buffer
) + 2 * size
, GFP_ATOMIC
);
343 p
->char_buf_ptr
= (char *)(p
->data
);
344 p
->flag_buf_ptr
= (unsigned char *)p
->char_buf_ptr
+ size
;
345 tty
->buf
.memory_used
+= size
;
350 * tty_buffer_free - free a tty buffer
351 * @tty: tty owning the buffer
352 * @b: the buffer to free
354 * Free a tty buffer, or add it to the free list according to our
357 * Locking: Caller must hold tty->buf.lock
360 static void tty_buffer_free(struct tty_struct
*tty
, struct tty_buffer
*b
)
362 /* Dumb strategy for now - should keep some stats */
363 tty
->buf
.memory_used
-= b
->size
;
364 WARN_ON(tty
->buf
.memory_used
< 0);
369 b
->next
= tty
->buf
.free
;
375 * __tty_buffer_flush - flush full tty buffers
378 * flush all the buffers containing receive data. Caller must
379 * hold the buffer lock and must have ensured no parallel flush to
382 * Locking: Caller must hold tty->buf.lock
385 static void __tty_buffer_flush(struct tty_struct
*tty
)
387 struct tty_buffer
*thead
;
389 while ((thead
= tty
->buf
.head
) != NULL
) {
390 tty
->buf
.head
= thead
->next
;
391 tty_buffer_free(tty
, thead
);
393 tty
->buf
.tail
= NULL
;
397 * tty_buffer_flush - flush full tty buffers
400 * flush all the buffers containing receive data. If the buffer is
401 * being processed by flush_to_ldisc then we defer the processing
407 static void tty_buffer_flush(struct tty_struct
*tty
)
410 spin_lock_irqsave(&tty
->buf
.lock
, flags
);
412 /* If the data is being pushed to the tty layer then we can't
413 process it here. Instead set a flag and the flush_to_ldisc
414 path will process the flush request before it exits */
415 if (test_bit(TTY_FLUSHING
, &tty
->flags
)) {
416 set_bit(TTY_FLUSHPENDING
, &tty
->flags
);
417 spin_unlock_irqrestore(&tty
->buf
.lock
, flags
);
418 wait_event(tty
->read_wait
,
419 test_bit(TTY_FLUSHPENDING
, &tty
->flags
) == 0);
422 __tty_buffer_flush(tty
);
423 spin_unlock_irqrestore(&tty
->buf
.lock
, flags
);
427 * tty_buffer_find - find a free tty buffer
428 * @tty: tty owning the buffer
429 * @size: characters wanted
431 * Locate an existing suitable tty buffer or if we are lacking one then
432 * allocate a new one. We round our buffers off in 256 character chunks
433 * to get better allocation behaviour.
435 * Locking: Caller must hold tty->buf.lock
438 static struct tty_buffer
*tty_buffer_find(struct tty_struct
*tty
, size_t size
)
440 struct tty_buffer
**tbh
= &tty
->buf
.free
;
441 while ((*tbh
) != NULL
) {
442 struct tty_buffer
*t
= *tbh
;
443 if (t
->size
>= size
) {
449 tty
->buf
.memory_used
+= t
->size
;
452 tbh
= &((*tbh
)->next
);
454 /* Round the buffer size out */
455 size
= (size
+ 0xFF) & ~0xFF;
456 return tty_buffer_alloc(tty
, size
);
457 /* Should possibly check if this fails for the largest buffer we
458 have queued and recycle that ? */
462 * tty_buffer_request_room - grow tty buffer if needed
463 * @tty: tty structure
464 * @size: size desired
466 * Make at least size bytes of linear space available for the tty
467 * buffer. If we fail return the size we managed to find.
469 * Locking: Takes tty->buf.lock
471 int tty_buffer_request_room(struct tty_struct
*tty
, size_t size
)
473 struct tty_buffer
*b
, *n
;
477 spin_lock_irqsave(&tty
->buf
.lock
, flags
);
479 /* OPTIMISATION: We could keep a per tty "zero" sized buffer to
480 remove this conditional if its worth it. This would be invisible
482 if ((b
= tty
->buf
.tail
) != NULL
)
483 left
= b
->size
- b
->used
;
488 /* This is the slow path - looking for new buffers to use */
489 if ((n
= tty_buffer_find(tty
, size
)) != NULL
) {
500 spin_unlock_irqrestore(&tty
->buf
.lock
, flags
);
503 EXPORT_SYMBOL_GPL(tty_buffer_request_room
);
506 * tty_insert_flip_string - Add characters to the tty buffer
507 * @tty: tty structure
511 * Queue a series of bytes to the tty buffering. All the characters
512 * passed are marked as without error. Returns the number added.
514 * Locking: Called functions may take tty->buf.lock
517 int tty_insert_flip_string(struct tty_struct
*tty
, const unsigned char *chars
,
522 int space
= tty_buffer_request_room(tty
, size
- copied
);
523 struct tty_buffer
*tb
= tty
->buf
.tail
;
524 /* If there is no space then tb may be NULL */
525 if (unlikely(space
== 0))
527 memcpy(tb
->char_buf_ptr
+ tb
->used
, chars
, space
);
528 memset(tb
->flag_buf_ptr
+ tb
->used
, TTY_NORMAL
, space
);
532 /* There is a small chance that we need to split the data over
533 several buffers. If this is the case we must loop */
534 } while (unlikely(size
> copied
));
537 EXPORT_SYMBOL(tty_insert_flip_string
);
540 * tty_insert_flip_string_flags - Add characters to the tty buffer
541 * @tty: tty structure
546 * Queue a series of bytes to the tty buffering. For each character
547 * the flags array indicates the status of the character. Returns the
550 * Locking: Called functions may take tty->buf.lock
553 int tty_insert_flip_string_flags(struct tty_struct
*tty
,
554 const unsigned char *chars
, const char *flags
, size_t size
)
558 int space
= tty_buffer_request_room(tty
, size
- copied
);
559 struct tty_buffer
*tb
= tty
->buf
.tail
;
560 /* If there is no space then tb may be NULL */
561 if (unlikely(space
== 0))
563 memcpy(tb
->char_buf_ptr
+ tb
->used
, chars
, space
);
564 memcpy(tb
->flag_buf_ptr
+ tb
->used
, flags
, space
);
569 /* There is a small chance that we need to split the data over
570 several buffers. If this is the case we must loop */
571 } while (unlikely(size
> copied
));
574 EXPORT_SYMBOL(tty_insert_flip_string_flags
);
577 * tty_schedule_flip - push characters to ldisc
578 * @tty: tty to push from
580 * Takes any pending buffers and transfers their ownership to the
581 * ldisc side of the queue. It then schedules those characters for
582 * processing by the line discipline.
584 * Locking: Takes tty->buf.lock
587 void tty_schedule_flip(struct tty_struct
*tty
)
590 spin_lock_irqsave(&tty
->buf
.lock
, flags
);
591 if (tty
->buf
.tail
!= NULL
)
592 tty
->buf
.tail
->commit
= tty
->buf
.tail
->used
;
593 spin_unlock_irqrestore(&tty
->buf
.lock
, flags
);
594 schedule_delayed_work(&tty
->buf
.work
, 1);
596 EXPORT_SYMBOL(tty_schedule_flip
);
599 * tty_prepare_flip_string - make room for characters
601 * @chars: return pointer for character write area
602 * @size: desired size
604 * Prepare a block of space in the buffer for data. Returns the length
605 * available and buffer pointer to the space which is now allocated and
606 * accounted for as ready for normal characters. This is used for drivers
607 * that need their own block copy routines into the buffer. There is no
608 * guarantee the buffer is a DMA target!
610 * Locking: May call functions taking tty->buf.lock
613 int tty_prepare_flip_string(struct tty_struct
*tty
, unsigned char **chars
,
616 int space
= tty_buffer_request_room(tty
, size
);
618 struct tty_buffer
*tb
= tty
->buf
.tail
;
619 *chars
= tb
->char_buf_ptr
+ tb
->used
;
620 memset(tb
->flag_buf_ptr
+ tb
->used
, TTY_NORMAL
, space
);
626 EXPORT_SYMBOL_GPL(tty_prepare_flip_string
);
629 * tty_prepare_flip_string_flags - make room for characters
631 * @chars: return pointer for character write area
632 * @flags: return pointer for status flag write area
633 * @size: desired size
635 * Prepare a block of space in the buffer for data. Returns the length
636 * available and buffer pointer to the space which is now allocated and
637 * accounted for as ready for characters. This is used for drivers
638 * that need their own block copy routines into the buffer. There is no
639 * guarantee the buffer is a DMA target!
641 * Locking: May call functions taking tty->buf.lock
644 int tty_prepare_flip_string_flags(struct tty_struct
*tty
,
645 unsigned char **chars
, char **flags
, size_t size
)
647 int space
= tty_buffer_request_room(tty
, size
);
649 struct tty_buffer
*tb
= tty
->buf
.tail
;
650 *chars
= tb
->char_buf_ptr
+ tb
->used
;
651 *flags
= tb
->flag_buf_ptr
+ tb
->used
;
657 EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags
);
662 * tty_set_termios_ldisc - set ldisc field
663 * @tty: tty structure
664 * @num: line discipline number
666 * This is probably overkill for real world processors but
667 * they are not on hot paths so a little discipline won't do
670 * Locking: takes termios_mutex
673 static void tty_set_termios_ldisc(struct tty_struct
*tty
, int num
)
675 mutex_lock(&tty
->termios_mutex
);
676 tty
->termios
->c_line
= num
;
677 mutex_unlock(&tty
->termios_mutex
);
681 * This guards the refcounted line discipline lists. The lock
682 * must be taken with irqs off because there are hangup path
683 * callers who will do ldisc lookups and cannot sleep.
686 static DEFINE_SPINLOCK(tty_ldisc_lock
);
687 static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_wait
);
688 /* Line disc dispatch table */
689 static struct tty_ldisc tty_ldiscs
[NR_LDISCS
];
692 * tty_register_ldisc - install a line discipline
693 * @disc: ldisc number
694 * @new_ldisc: pointer to the ldisc object
696 * Installs a new line discipline into the kernel. The discipline
697 * is set up as unreferenced and then made available to the kernel
698 * from this point onwards.
701 * takes tty_ldisc_lock to guard against ldisc races
704 int tty_register_ldisc(int disc
, struct tty_ldisc
*new_ldisc
)
709 if (disc
< N_TTY
|| disc
>= NR_LDISCS
)
712 spin_lock_irqsave(&tty_ldisc_lock
, flags
);
713 tty_ldiscs
[disc
] = *new_ldisc
;
714 tty_ldiscs
[disc
].num
= disc
;
715 tty_ldiscs
[disc
].flags
|= LDISC_FLAG_DEFINED
;
716 tty_ldiscs
[disc
].refcount
= 0;
717 spin_unlock_irqrestore(&tty_ldisc_lock
, flags
);
721 EXPORT_SYMBOL(tty_register_ldisc
);
724 * tty_unregister_ldisc - unload a line discipline
725 * @disc: ldisc number
726 * @new_ldisc: pointer to the ldisc object
728 * Remove a line discipline from the kernel providing it is not
732 * takes tty_ldisc_lock to guard against ldisc races
735 int tty_unregister_ldisc(int disc
)
740 if (disc
< N_TTY
|| disc
>= NR_LDISCS
)
743 spin_lock_irqsave(&tty_ldisc_lock
, flags
);
744 if (tty_ldiscs
[disc
].refcount
)
747 tty_ldiscs
[disc
].flags
&= ~LDISC_FLAG_DEFINED
;
748 spin_unlock_irqrestore(&tty_ldisc_lock
, flags
);
752 EXPORT_SYMBOL(tty_unregister_ldisc
);
755 * tty_ldisc_get - take a reference to an ldisc
756 * @disc: ldisc number
758 * Takes a reference to a line discipline. Deals with refcounts and
759 * module locking counts. Returns NULL if the discipline is not available.
760 * Returns a pointer to the discipline and bumps the ref count if it is
764 * takes tty_ldisc_lock to guard against ldisc races
767 struct tty_ldisc
*tty_ldisc_get(int disc
)
770 struct tty_ldisc
*ld
;
772 if (disc
< N_TTY
|| disc
>= NR_LDISCS
)
775 spin_lock_irqsave(&tty_ldisc_lock
, flags
);
777 ld
= &tty_ldiscs
[disc
];
778 /* Check the entry is defined */
779 if (ld
->flags
& LDISC_FLAG_DEFINED
) {
780 /* If the module is being unloaded we can't use it */
781 if (!try_module_get(ld
->owner
))
787 spin_unlock_irqrestore(&tty_ldisc_lock
, flags
);
791 EXPORT_SYMBOL_GPL(tty_ldisc_get
);
794 * tty_ldisc_put - drop ldisc reference
795 * @disc: ldisc number
797 * Drop a reference to a line discipline. Manage refcounts and
798 * module usage counts
801 * takes tty_ldisc_lock to guard against ldisc races
804 void tty_ldisc_put(int disc
)
806 struct tty_ldisc
*ld
;
809 BUG_ON(disc
< N_TTY
|| disc
>= NR_LDISCS
);
811 spin_lock_irqsave(&tty_ldisc_lock
, flags
);
812 ld
= &tty_ldiscs
[disc
];
813 BUG_ON(ld
->refcount
== 0);
815 module_put(ld
->owner
);
816 spin_unlock_irqrestore(&tty_ldisc_lock
, flags
);
819 EXPORT_SYMBOL_GPL(tty_ldisc_put
);
822 * tty_ldisc_assign - set ldisc on a tty
823 * @tty: tty to assign
824 * @ld: line discipline
826 * Install an instance of a line discipline into a tty structure. The
827 * ldisc must have a reference count above zero to ensure it remains/
828 * The tty instance refcount starts at zero.
831 * Caller must hold references
834 static void tty_ldisc_assign(struct tty_struct
*tty
, struct tty_ldisc
*ld
)
837 tty
->ldisc
.refcount
= 0;
841 * tty_ldisc_try - internal helper
844 * Make a single attempt to grab and bump the refcount on
845 * the tty ldisc. Return 0 on failure or 1 on success. This is
846 * used to implement both the waiting and non waiting versions
849 * Locking: takes tty_ldisc_lock
852 static int tty_ldisc_try(struct tty_struct
*tty
)
855 struct tty_ldisc
*ld
;
858 spin_lock_irqsave(&tty_ldisc_lock
, flags
);
860 if (test_bit(TTY_LDISC
, &tty
->flags
)) {
864 spin_unlock_irqrestore(&tty_ldisc_lock
, flags
);
869 * tty_ldisc_ref_wait - wait for the tty ldisc
872 * Dereference the line discipline for the terminal and take a
873 * reference to it. If the line discipline is in flux then
874 * wait patiently until it changes.
876 * Note: Must not be called from an IRQ/timer context. The caller
877 * must also be careful not to hold other locks that will deadlock
878 * against a discipline change, such as an existing ldisc reference
879 * (which we check for)
881 * Locking: call functions take tty_ldisc_lock
884 struct tty_ldisc
*tty_ldisc_ref_wait(struct tty_struct
*tty
)
886 /* wait_event is a macro */
887 wait_event(tty_ldisc_wait
, tty_ldisc_try(tty
));
888 if (tty
->ldisc
.refcount
== 0)
889 printk(KERN_ERR
"tty_ldisc_ref_wait\n");
893 EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait
);
896 * tty_ldisc_ref - get the tty ldisc
899 * Dereference the line discipline for the terminal and take a
900 * reference to it. If the line discipline is in flux then
901 * return NULL. Can be called from IRQ and timer functions.
903 * Locking: called functions take tty_ldisc_lock
906 struct tty_ldisc
*tty_ldisc_ref(struct tty_struct
*tty
)
908 if (tty_ldisc_try(tty
))
913 EXPORT_SYMBOL_GPL(tty_ldisc_ref
);
916 * tty_ldisc_deref - free a tty ldisc reference
917 * @ld: reference to free up
919 * Undoes the effect of tty_ldisc_ref or tty_ldisc_ref_wait. May
920 * be called in IRQ context.
922 * Locking: takes tty_ldisc_lock
925 void tty_ldisc_deref(struct tty_ldisc
*ld
)
931 spin_lock_irqsave(&tty_ldisc_lock
, flags
);
932 if (ld
->refcount
== 0)
933 printk(KERN_ERR
"tty_ldisc_deref: no references.\n");
936 if (ld
->refcount
== 0)
937 wake_up(&tty_ldisc_wait
);
938 spin_unlock_irqrestore(&tty_ldisc_lock
, flags
);
941 EXPORT_SYMBOL_GPL(tty_ldisc_deref
);
944 * tty_ldisc_enable - allow ldisc use
945 * @tty: terminal to activate ldisc on
947 * Set the TTY_LDISC flag when the line discipline can be called
948 * again. Do necessary wakeups for existing sleepers.
950 * Note: nobody should set this bit except via this function. Clearing
951 * directly is allowed.
954 static void tty_ldisc_enable(struct tty_struct
*tty
)
956 set_bit(TTY_LDISC
, &tty
->flags
);
957 wake_up(&tty_ldisc_wait
);
961 * tty_set_ldisc - set line discipline
962 * @tty: the terminal to set
963 * @ldisc: the line discipline
965 * Set the discipline of a tty line. Must be called from a process
968 * Locking: takes tty_ldisc_lock.
969 * called functions take termios_mutex
972 static int tty_set_ldisc(struct tty_struct
*tty
, int ldisc
)
975 struct tty_ldisc o_ldisc
;
979 struct tty_ldisc
*ld
;
980 struct tty_struct
*o_tty
;
982 if ((ldisc
< N_TTY
) || (ldisc
>= NR_LDISCS
))
987 ld
= tty_ldisc_get(ldisc
);
988 /* Eduardo Blanco <ejbs@cs.cs.com.uy> */
989 /* Cyrus Durgin <cider@speakeasy.org> */
991 request_module("tty-ldisc-%d", ldisc
);
992 ld
= tty_ldisc_get(ldisc
);
998 * Problem: What do we do if this blocks ?
1001 tty_wait_until_sent(tty
, 0);
1003 if (tty
->ldisc
.num
== ldisc
) {
1004 tty_ldisc_put(ldisc
);
1009 * No more input please, we are switching. The new ldisc
1010 * will update this value in the ldisc open function
1013 tty
->receive_room
= 0;
1015 o_ldisc
= tty
->ldisc
;
1019 * Make sure we don't change while someone holds a
1020 * reference to the line discipline. The TTY_LDISC bit
1021 * prevents anyone taking a reference once it is clear.
1022 * We need the lock to avoid racing reference takers.
1025 spin_lock_irqsave(&tty_ldisc_lock
, flags
);
1026 if (tty
->ldisc
.refcount
|| (o_tty
&& o_tty
->ldisc
.refcount
)) {
1027 if (tty
->ldisc
.refcount
) {
1028 /* Free the new ldisc we grabbed. Must drop the lock
1030 spin_unlock_irqrestore(&tty_ldisc_lock
, flags
);
1031 tty_ldisc_put(ldisc
);
1033 * There are several reasons we may be busy, including
1034 * random momentary I/O traffic. We must therefore
1035 * retry. We could distinguish between blocking ops
1036 * and retries if we made tty_ldisc_wait() smarter.
1037 * That is up for discussion.
1039 if (wait_event_interruptible(tty_ldisc_wait
, tty
->ldisc
.refcount
== 0) < 0)
1040 return -ERESTARTSYS
;
1043 if (o_tty
&& o_tty
->ldisc
.refcount
) {
1044 spin_unlock_irqrestore(&tty_ldisc_lock
, flags
);
1045 tty_ldisc_put(ldisc
);
1046 if (wait_event_interruptible(tty_ldisc_wait
, o_tty
->ldisc
.refcount
== 0) < 0)
1047 return -ERESTARTSYS
;
1052 * If the TTY_LDISC bit is set, then we are racing against
1053 * another ldisc change
1055 if (!test_bit(TTY_LDISC
, &tty
->flags
)) {
1056 spin_unlock_irqrestore(&tty_ldisc_lock
, flags
);
1057 tty_ldisc_put(ldisc
);
1058 ld
= tty_ldisc_ref_wait(tty
);
1059 tty_ldisc_deref(ld
);
1063 clear_bit(TTY_LDISC
, &tty
->flags
);
1065 clear_bit(TTY_LDISC
, &o_tty
->flags
);
1066 spin_unlock_irqrestore(&tty_ldisc_lock
, flags
);
1069 * From this point on we know nobody has an ldisc
1070 * usage reference, nor can they obtain one until
1071 * we say so later on.
1074 work
= cancel_delayed_work(&tty
->buf
.work
);
1076 * Wait for ->hangup_work and ->buf.work handlers to terminate
1078 flush_scheduled_work();
1079 /* Shutdown the current discipline. */
1080 if (tty
->ldisc
.close
)
1081 (tty
->ldisc
.close
)(tty
);
1083 /* Now set up the new line discipline. */
1084 tty_ldisc_assign(tty
, ld
);
1085 tty_set_termios_ldisc(tty
, ldisc
);
1086 if (tty
->ldisc
.open
)
1087 retval
= (tty
->ldisc
.open
)(tty
);
1089 tty_ldisc_put(ldisc
);
1090 /* There is an outstanding reference here so this is safe */
1091 tty_ldisc_assign(tty
, tty_ldisc_get(o_ldisc
.num
));
1092 tty_set_termios_ldisc(tty
, tty
->ldisc
.num
);
1093 if (tty
->ldisc
.open
&& (tty
->ldisc
.open(tty
) < 0)) {
1094 tty_ldisc_put(o_ldisc
.num
);
1095 /* This driver is always present */
1096 tty_ldisc_assign(tty
, tty_ldisc_get(N_TTY
));
1097 tty_set_termios_ldisc(tty
, N_TTY
);
1098 if (tty
->ldisc
.open
) {
1099 int r
= tty
->ldisc
.open(tty
);
1102 panic("Couldn't open N_TTY ldisc for "
1104 tty_name(tty
, buf
), r
);
1108 /* At this point we hold a reference to the new ldisc and a
1109 a reference to the old ldisc. If we ended up flipping back
1110 to the existing ldisc we have two references to it */
1112 if (tty
->ldisc
.num
!= o_ldisc
.num
&& tty
->driver
->set_ldisc
)
1113 tty
->driver
->set_ldisc(tty
);
1115 tty_ldisc_put(o_ldisc
.num
);
1118 * Allow ldisc referencing to occur as soon as the driver
1119 * ldisc callback completes.
1122 tty_ldisc_enable(tty
);
1124 tty_ldisc_enable(o_tty
);
1126 /* Restart it in case no characters kick it off. Safe if
1129 schedule_delayed_work(&tty
->buf
.work
, 1);
1134 * get_tty_driver - find device of a tty
1135 * @dev_t: device identifier
1136 * @index: returns the index of the tty
1138 * This routine returns a tty driver structure, given a device number
1139 * and also passes back the index number.
1141 * Locking: caller must hold tty_mutex
1144 static struct tty_driver
*get_tty_driver(dev_t device
, int *index
)
1146 struct tty_driver
*p
;
1148 list_for_each_entry(p
, &tty_drivers
, tty_drivers
) {
1149 dev_t base
= MKDEV(p
->major
, p
->minor_start
);
1150 if (device
< base
|| device
>= base
+ p
->num
)
1152 *index
= device
- base
;
1158 #ifdef CONFIG_CONSOLE_POLL
1161 * tty_find_polling_driver - find device of a polled tty
1162 * @name: name string to match
1163 * @line: pointer to resulting tty line nr
1165 * This routine returns a tty driver structure, given a name
1166 * and the condition that the tty driver is capable of polled
1169 struct tty_driver
*tty_find_polling_driver(char *name
, int *line
)
1171 struct tty_driver
*p
, *res
= NULL
;
1175 mutex_lock(&tty_mutex
);
1176 /* Search through the tty devices to look for a match */
1177 list_for_each_entry(p
, &tty_drivers
, tty_drivers
) {
1178 str
= name
+ strlen(p
->name
);
1179 tty_line
= simple_strtoul(str
, &str
, 10);
1185 if (tty_line
>= 0 && tty_line
<= p
->num
&& p
->poll_init
&&
1186 !p
->poll_init(p
, tty_line
, str
)) {
1193 mutex_unlock(&tty_mutex
);
1197 EXPORT_SYMBOL_GPL(tty_find_polling_driver
);
1201 * tty_check_change - check for POSIX terminal changes
1202 * @tty: tty to check
1204 * If we try to write to, or set the state of, a terminal and we're
1205 * not in the foreground, send a SIGTTOU. If the signal is blocked or
1206 * ignored, go ahead and perform the operation. (POSIX 7.2)
1211 int tty_check_change(struct tty_struct
*tty
)
1213 if (current
->signal
->tty
!= tty
)
1216 printk(KERN_WARNING
"tty_check_change: tty->pgrp == NULL!\n");
1219 if (task_pgrp(current
) == tty
->pgrp
)
1221 if (is_ignored(SIGTTOU
))
1223 if (is_current_pgrp_orphaned())
1225 kill_pgrp(task_pgrp(current
), SIGTTOU
, 1);
1226 set_thread_flag(TIF_SIGPENDING
);
1227 return -ERESTARTSYS
;
1230 EXPORT_SYMBOL(tty_check_change
);
1232 static ssize_t
hung_up_tty_read(struct file
*file
, char __user
*buf
,
1233 size_t count
, loff_t
*ppos
)
1238 static ssize_t
hung_up_tty_write(struct file
*file
, const char __user
*buf
,
1239 size_t count
, loff_t
*ppos
)
1244 /* No kernel lock held - none needed ;) */
1245 static unsigned int hung_up_tty_poll(struct file
*filp
, poll_table
*wait
)
1247 return POLLIN
| POLLOUT
| POLLERR
| POLLHUP
| POLLRDNORM
| POLLWRNORM
;
1250 static int hung_up_tty_ioctl(struct inode
*inode
, struct file
*file
,
1251 unsigned int cmd
, unsigned long arg
)
1253 return cmd
== TIOCSPGRP
? -ENOTTY
: -EIO
;
1256 static long hung_up_tty_compat_ioctl(struct file
*file
,
1257 unsigned int cmd
, unsigned long arg
)
1259 return cmd
== TIOCSPGRP
? -ENOTTY
: -EIO
;
1262 static const struct file_operations tty_fops
= {
1263 .llseek
= no_llseek
,
1268 .compat_ioctl
= tty_compat_ioctl
,
1270 .release
= tty_release
,
1271 .fasync
= tty_fasync
,
1274 #ifdef CONFIG_UNIX98_PTYS
1275 static const struct file_operations ptmx_fops
= {
1276 .llseek
= no_llseek
,
1281 .compat_ioctl
= tty_compat_ioctl
,
1283 .release
= tty_release
,
1284 .fasync
= tty_fasync
,
1288 static const struct file_operations console_fops
= {
1289 .llseek
= no_llseek
,
1291 .write
= redirected_tty_write
,
1294 .compat_ioctl
= tty_compat_ioctl
,
1296 .release
= tty_release
,
1297 .fasync
= tty_fasync
,
1300 static const struct file_operations hung_up_tty_fops
= {
1301 .llseek
= no_llseek
,
1302 .read
= hung_up_tty_read
,
1303 .write
= hung_up_tty_write
,
1304 .poll
= hung_up_tty_poll
,
1305 .ioctl
= hung_up_tty_ioctl
,
1306 .compat_ioctl
= hung_up_tty_compat_ioctl
,
1307 .release
= tty_release
,
1310 static DEFINE_SPINLOCK(redirect_lock
);
1311 static struct file
*redirect
;
1314 * tty_wakeup - request more data
1317 * Internal and external helper for wakeups of tty. This function
1318 * informs the line discipline if present that the driver is ready
1319 * to receive more output data.
1322 void tty_wakeup(struct tty_struct
*tty
)
1324 struct tty_ldisc
*ld
;
1326 if (test_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
)) {
1327 ld
= tty_ldisc_ref(tty
);
1329 if (ld
->write_wakeup
)
1330 ld
->write_wakeup(tty
);
1331 tty_ldisc_deref(ld
);
1334 wake_up_interruptible(&tty
->write_wait
);
1337 EXPORT_SYMBOL_GPL(tty_wakeup
);
1340 * tty_ldisc_flush - flush line discipline queue
1343 * Flush the line discipline queue (if any) for this tty. If there
1344 * is no line discipline active this is a no-op.
1347 void tty_ldisc_flush(struct tty_struct
*tty
)
1349 struct tty_ldisc
*ld
= tty_ldisc_ref(tty
);
1351 if (ld
->flush_buffer
)
1352 ld
->flush_buffer(tty
);
1353 tty_ldisc_deref(ld
);
1355 tty_buffer_flush(tty
);
1358 EXPORT_SYMBOL_GPL(tty_ldisc_flush
);
1361 * tty_reset_termios - reset terminal state
1362 * @tty: tty to reset
1364 * Restore a terminal to the driver default state
1367 static void tty_reset_termios(struct tty_struct
*tty
)
1369 mutex_lock(&tty
->termios_mutex
);
1370 *tty
->termios
= tty
->driver
->init_termios
;
1371 tty
->termios
->c_ispeed
= tty_termios_input_baud_rate(tty
->termios
);
1372 tty
->termios
->c_ospeed
= tty_termios_baud_rate(tty
->termios
);
1373 mutex_unlock(&tty
->termios_mutex
);
1377 * do_tty_hangup - actual handler for hangup events
1380 * This can be called by the "eventd" kernel thread. That is process
1381 * synchronous but doesn't hold any locks, so we need to make sure we
1382 * have the appropriate locks for what we're doing.
1384 * The hangup event clears any pending redirections onto the hung up
1385 * device. It ensures future writes will error and it does the needed
1386 * line discipline hangup and signal delivery. The tty object itself
1391 * redirect lock for undoing redirection
1392 * file list lock for manipulating list of ttys
1393 * tty_ldisc_lock from called functions
1394 * termios_mutex resetting termios data
1395 * tasklist_lock to walk task list for hangup event
1396 * ->siglock to protect ->signal/->sighand
1398 static void do_tty_hangup(struct work_struct
*work
)
1400 struct tty_struct
*tty
=
1401 container_of(work
, struct tty_struct
, hangup_work
);
1402 struct file
*cons_filp
= NULL
;
1403 struct file
*filp
, *f
= NULL
;
1404 struct task_struct
*p
;
1405 struct tty_ldisc
*ld
;
1406 int closecount
= 0, n
;
1411 /* inuse_filps is protected by the single kernel lock */
1414 spin_lock(&redirect_lock
);
1415 if (redirect
&& redirect
->private_data
== tty
) {
1419 spin_unlock(&redirect_lock
);
1421 check_tty_count(tty
, "do_tty_hangup");
1423 /* This breaks for file handles being sent over AF_UNIX sockets ? */
1424 list_for_each_entry(filp
, &tty
->tty_files
, f_u
.fu_list
) {
1425 if (filp
->f_op
->write
== redirected_tty_write
)
1427 if (filp
->f_op
->write
!= tty_write
)
1430 tty_fasync(-1, filp
, 0); /* can't block */
1431 filp
->f_op
= &hung_up_tty_fops
;
1435 * FIXME! What are the locking issues here? This may me overdoing
1436 * things... This question is especially important now that we've
1437 * removed the irqlock.
1439 ld
= tty_ldisc_ref(tty
);
1441 /* We may have no line discipline at this point */
1442 if (ld
->flush_buffer
)
1443 ld
->flush_buffer(tty
);
1444 if (tty
->driver
->flush_buffer
)
1445 tty
->driver
->flush_buffer(tty
);
1446 if ((test_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
)) &&
1448 ld
->write_wakeup(tty
);
1453 * FIXME: Once we trust the LDISC code better we can wait here for
1454 * ldisc completion and fix the driver call race
1456 wake_up_interruptible(&tty
->write_wait
);
1457 wake_up_interruptible(&tty
->read_wait
);
1459 * Shutdown the current line discipline, and reset it to
1462 if (tty
->driver
->flags
& TTY_DRIVER_RESET_TERMIOS
)
1463 tty_reset_termios(tty
);
1464 /* Defer ldisc switch */
1465 /* tty_deferred_ldisc_switch(N_TTY);
1467 This should get done automatically when the port closes and
1468 tty_release is called */
1470 read_lock(&tasklist_lock
);
1472 do_each_pid_task(tty
->session
, PIDTYPE_SID
, p
) {
1473 spin_lock_irq(&p
->sighand
->siglock
);
1474 if (p
->signal
->tty
== tty
)
1475 p
->signal
->tty
= NULL
;
1476 if (!p
->signal
->leader
) {
1477 spin_unlock_irq(&p
->sighand
->siglock
);
1480 __group_send_sig_info(SIGHUP
, SEND_SIG_PRIV
, p
);
1481 __group_send_sig_info(SIGCONT
, SEND_SIG_PRIV
, p
);
1482 put_pid(p
->signal
->tty_old_pgrp
); /* A noop */
1484 p
->signal
->tty_old_pgrp
= get_pid(tty
->pgrp
);
1485 spin_unlock_irq(&p
->sighand
->siglock
);
1486 } while_each_pid_task(tty
->session
, PIDTYPE_SID
, p
);
1488 read_unlock(&tasklist_lock
);
1491 put_pid(tty
->session
);
1493 tty
->session
= NULL
;
1495 tty
->ctrl_status
= 0;
1497 * If one of the devices matches a console pointer, we
1498 * cannot just call hangup() because that will cause
1499 * tty->count and state->count to go out of sync.
1500 * So we just call close() the right number of times.
1503 if (tty
->driver
->close
)
1504 for (n
= 0; n
< closecount
; n
++)
1505 tty
->driver
->close(tty
, cons_filp
);
1506 } else if (tty
->driver
->hangup
)
1507 (tty
->driver
->hangup
)(tty
);
1509 * We don't want to have driver/ldisc interactions beyond
1510 * the ones we did here. The driver layer expects no
1511 * calls after ->hangup() from the ldisc side. However we
1512 * can't yet guarantee all that.
1514 set_bit(TTY_HUPPED
, &tty
->flags
);
1516 tty_ldisc_enable(tty
);
1517 tty_ldisc_deref(ld
);
1525 * tty_hangup - trigger a hangup event
1526 * @tty: tty to hangup
1528 * A carrier loss (virtual or otherwise) has occurred on this like
1529 * schedule a hangup sequence to run after this event.
1532 void tty_hangup(struct tty_struct
*tty
)
1534 #ifdef TTY_DEBUG_HANGUP
1536 printk(KERN_DEBUG
"%s hangup...\n", tty_name(tty
, buf
));
1538 schedule_work(&tty
->hangup_work
);
1541 EXPORT_SYMBOL(tty_hangup
);
1544 * tty_vhangup - process vhangup
1545 * @tty: tty to hangup
1547 * The user has asked via system call for the terminal to be hung up.
1548 * We do this synchronously so that when the syscall returns the process
1549 * is complete. That guarantee is necessary for security reasons.
1552 void tty_vhangup(struct tty_struct
*tty
)
1554 #ifdef TTY_DEBUG_HANGUP
1557 printk(KERN_DEBUG
"%s vhangup...\n", tty_name(tty
, buf
));
1559 do_tty_hangup(&tty
->hangup_work
);
1562 EXPORT_SYMBOL(tty_vhangup
);
1565 * tty_hung_up_p - was tty hung up
1566 * @filp: file pointer of tty
1568 * Return true if the tty has been subject to a vhangup or a carrier
1572 int tty_hung_up_p(struct file
*filp
)
1574 return (filp
->f_op
== &hung_up_tty_fops
);
1577 EXPORT_SYMBOL(tty_hung_up_p
);
1580 * is_tty - checker whether file is a TTY
1581 * @filp: file handle that may be a tty
1583 * Check if the file handle is a tty handle.
1586 int is_tty(struct file
*filp
)
1588 return filp
->f_op
->read
== tty_read
1589 || filp
->f_op
->read
== hung_up_tty_read
;
1592 static void session_clear_tty(struct pid
*session
)
1594 struct task_struct
*p
;
1595 do_each_pid_task(session
, PIDTYPE_SID
, p
) {
1597 } while_each_pid_task(session
, PIDTYPE_SID
, p
);
1601 * disassociate_ctty - disconnect controlling tty
1602 * @on_exit: true if exiting so need to "hang up" the session
1604 * This function is typically called only by the session leader, when
1605 * it wants to disassociate itself from its controlling tty.
1607 * It performs the following functions:
1608 * (1) Sends a SIGHUP and SIGCONT to the foreground process group
1609 * (2) Clears the tty from being controlling the session
1610 * (3) Clears the controlling tty for all processes in the
1613 * The argument on_exit is set to 1 if called when a process is
1614 * exiting; it is 0 if called by the ioctl TIOCNOTTY.
1617 * BKL is taken for hysterical raisins
1618 * tty_mutex is taken to protect tty
1619 * ->siglock is taken to protect ->signal/->sighand
1620 * tasklist_lock is taken to walk process list for sessions
1621 * ->siglock is taken to protect ->signal/->sighand
1624 void disassociate_ctty(int on_exit
)
1626 struct tty_struct
*tty
;
1627 struct pid
*tty_pgrp
= NULL
;
1631 mutex_lock(&tty_mutex
);
1632 tty
= get_current_tty();
1634 tty_pgrp
= get_pid(tty
->pgrp
);
1635 mutex_unlock(&tty_mutex
);
1636 /* XXX: here we race, there is nothing protecting tty */
1637 if (on_exit
&& tty
->driver
->type
!= TTY_DRIVER_TYPE_PTY
)
1639 } else if (on_exit
) {
1640 struct pid
*old_pgrp
;
1641 spin_lock_irq(¤t
->sighand
->siglock
);
1642 old_pgrp
= current
->signal
->tty_old_pgrp
;
1643 current
->signal
->tty_old_pgrp
= NULL
;
1644 spin_unlock_irq(¤t
->sighand
->siglock
);
1646 kill_pgrp(old_pgrp
, SIGHUP
, on_exit
);
1647 kill_pgrp(old_pgrp
, SIGCONT
, on_exit
);
1650 mutex_unlock(&tty_mutex
);
1655 kill_pgrp(tty_pgrp
, SIGHUP
, on_exit
);
1657 kill_pgrp(tty_pgrp
, SIGCONT
, on_exit
);
1661 spin_lock_irq(¤t
->sighand
->siglock
);
1662 put_pid(current
->signal
->tty_old_pgrp
);
1663 current
->signal
->tty_old_pgrp
= NULL
;
1664 spin_unlock_irq(¤t
->sighand
->siglock
);
1666 mutex_lock(&tty_mutex
);
1667 /* It is possible that do_tty_hangup has free'd this tty */
1668 tty
= get_current_tty();
1670 put_pid(tty
->session
);
1672 tty
->session
= NULL
;
1675 #ifdef TTY_DEBUG_HANGUP
1676 printk(KERN_DEBUG
"error attempted to write to tty [0x%p]"
1680 mutex_unlock(&tty_mutex
);
1682 /* Now clear signal->tty under the lock */
1683 read_lock(&tasklist_lock
);
1684 session_clear_tty(task_session(current
));
1685 read_unlock(&tasklist_lock
);
1691 * no_tty - Ensure the current process does not have a controlling tty
1695 struct task_struct
*tsk
= current
;
1696 if (tsk
->signal
->leader
)
1697 disassociate_ctty(0);
1698 proc_clear_tty(tsk
);
1703 * stop_tty - propagate flow control
1706 * Perform flow control to the driver. For PTY/TTY pairs we
1707 * must also propagate the TIOCKPKT status. May be called
1708 * on an already stopped device and will not re-call the driver
1711 * This functionality is used by both the line disciplines for
1712 * halting incoming flow and by the driver. It may therefore be
1713 * called from any context, may be under the tty atomic_write_lock
1717 * Broken. Relies on BKL which is unsafe here.
1720 void stop_tty(struct tty_struct
*tty
)
1725 if (tty
->link
&& tty
->link
->packet
) {
1726 tty
->ctrl_status
&= ~TIOCPKT_START
;
1727 tty
->ctrl_status
|= TIOCPKT_STOP
;
1728 wake_up_interruptible(&tty
->link
->read_wait
);
1730 if (tty
->driver
->stop
)
1731 (tty
->driver
->stop
)(tty
);
1734 EXPORT_SYMBOL(stop_tty
);
1737 * start_tty - propagate flow control
1738 * @tty: tty to start
1740 * Start a tty that has been stopped if at all possible. Perform
1741 * any necessary wakeups and propagate the TIOCPKT status. If this
1742 * is the tty was previous stopped and is being started then the
1743 * driver start method is invoked and the line discipline woken.
1746 * Broken. Relies on BKL which is unsafe here.
1749 void start_tty(struct tty_struct
*tty
)
1751 if (!tty
->stopped
|| tty
->flow_stopped
)
1754 if (tty
->link
&& tty
->link
->packet
) {
1755 tty
->ctrl_status
&= ~TIOCPKT_STOP
;
1756 tty
->ctrl_status
|= TIOCPKT_START
;
1757 wake_up_interruptible(&tty
->link
->read_wait
);
1759 if (tty
->driver
->start
)
1760 (tty
->driver
->start
)(tty
);
1761 /* If we have a running line discipline it may need kicking */
1765 EXPORT_SYMBOL(start_tty
);
1768 * tty_read - read method for tty device files
1769 * @file: pointer to tty file
1771 * @count: size of user buffer
1774 * Perform the read system call function on this terminal device. Checks
1775 * for hung up devices before calling the line discipline method.
1778 * Locks the line discipline internally while needed
1779 * For historical reasons the line discipline read method is
1780 * invoked under the BKL. This will go away in time so do not rely on it
1781 * in new code. Multiple read calls may be outstanding in parallel.
1784 static ssize_t
tty_read(struct file
*file
, char __user
*buf
, size_t count
,
1788 struct tty_struct
*tty
;
1789 struct inode
*inode
;
1790 struct tty_ldisc
*ld
;
1792 tty
= (struct tty_struct
*)file
->private_data
;
1793 inode
= file
->f_path
.dentry
->d_inode
;
1794 if (tty_paranoia_check(tty
, inode
, "tty_read"))
1796 if (!tty
|| (test_bit(TTY_IO_ERROR
, &tty
->flags
)))
1799 /* We want to wait for the line discipline to sort out in this
1801 ld
= tty_ldisc_ref_wait(tty
);
1804 i
= (ld
->read
)(tty
, file
, buf
, count
);
1807 tty_ldisc_deref(ld
);
1810 inode
->i_atime
= current_fs_time(inode
->i_sb
);
1814 void tty_write_unlock(struct tty_struct
*tty
)
1816 mutex_unlock(&tty
->atomic_write_lock
);
1817 wake_up_interruptible(&tty
->write_wait
);
1820 int tty_write_lock(struct tty_struct
*tty
, int ndelay
)
1822 if (!mutex_trylock(&tty
->atomic_write_lock
)) {
1825 if (mutex_lock_interruptible(&tty
->atomic_write_lock
))
1826 return -ERESTARTSYS
;
1832 * Split writes up in sane blocksizes to avoid
1833 * denial-of-service type attacks
1835 static inline ssize_t
do_tty_write(
1836 ssize_t (*write
)(struct tty_struct
*, struct file
*, const unsigned char *, size_t),
1837 struct tty_struct
*tty
,
1839 const char __user
*buf
,
1842 ssize_t ret
, written
= 0;
1845 ret
= tty_write_lock(tty
, file
->f_flags
& O_NDELAY
);
1850 * We chunk up writes into a temporary buffer. This
1851 * simplifies low-level drivers immensely, since they
1852 * don't have locking issues and user mode accesses.
1854 * But if TTY_NO_WRITE_SPLIT is set, we should use a
1857 * The default chunk-size is 2kB, because the NTTY
1858 * layer has problems with bigger chunks. It will
1859 * claim to be able to handle more characters than
1862 * FIXME: This can probably go away now except that 64K chunks
1863 * are too likely to fail unless switched to vmalloc...
1866 if (test_bit(TTY_NO_WRITE_SPLIT
, &tty
->flags
))
1871 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
1872 if (tty
->write_cnt
< chunk
) {
1878 buf
= kmalloc(chunk
, GFP_KERNEL
);
1883 kfree(tty
->write_buf
);
1884 tty
->write_cnt
= chunk
;
1885 tty
->write_buf
= buf
;
1888 /* Do the write .. */
1890 size_t size
= count
;
1894 if (copy_from_user(tty
->write_buf
, buf
, size
))
1897 ret
= write(tty
, file
, tty
->write_buf
, size
);
1907 if (signal_pending(current
))
1912 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
1913 inode
->i_mtime
= current_fs_time(inode
->i_sb
);
1917 tty_write_unlock(tty
);
1923 * tty_write - write method for tty device file
1924 * @file: tty file pointer
1925 * @buf: user data to write
1926 * @count: bytes to write
1929 * Write data to a tty device via the line discipline.
1932 * Locks the line discipline as required
1933 * Writes to the tty driver are serialized by the atomic_write_lock
1934 * and are then processed in chunks to the device. The line discipline
1935 * write method will not be involked in parallel for each device
1936 * The line discipline write method is called under the big
1937 * kernel lock for historical reasons. New code should not rely on this.
1940 static ssize_t
tty_write(struct file
*file
, const char __user
*buf
,
1941 size_t count
, loff_t
*ppos
)
1943 struct tty_struct
*tty
;
1944 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
1946 struct tty_ldisc
*ld
;
1948 tty
= (struct tty_struct
*)file
->private_data
;
1949 if (tty_paranoia_check(tty
, inode
, "tty_write"))
1951 if (!tty
|| !tty
->driver
->write
||
1952 (test_bit(TTY_IO_ERROR
, &tty
->flags
)))
1955 ld
= tty_ldisc_ref_wait(tty
);
1959 ret
= do_tty_write(ld
->write
, tty
, file
, buf
, count
);
1960 tty_ldisc_deref(ld
);
1964 ssize_t
redirected_tty_write(struct file
*file
, const char __user
*buf
,
1965 size_t count
, loff_t
*ppos
)
1967 struct file
*p
= NULL
;
1969 spin_lock(&redirect_lock
);
1974 spin_unlock(&redirect_lock
);
1978 res
= vfs_write(p
, buf
, count
, &p
->f_pos
);
1982 return tty_write(file
, buf
, count
, ppos
);
1985 static char ptychar
[] = "pqrstuvwxyzabcde";
1988 * pty_line_name - generate name for a pty
1989 * @driver: the tty driver in use
1990 * @index: the minor number
1991 * @p: output buffer of at least 6 bytes
1993 * Generate a name from a driver reference and write it to the output
1998 static void pty_line_name(struct tty_driver
*driver
, int index
, char *p
)
2000 int i
= index
+ driver
->name_base
;
2001 /* ->name is initialized to "ttyp", but "tty" is expected */
2002 sprintf(p
, "%s%c%x",
2003 driver
->subtype
== PTY_TYPE_SLAVE
? "tty" : driver
->name
,
2004 ptychar
[i
>> 4 & 0xf], i
& 0xf);
2008 * pty_line_name - generate name for a tty
2009 * @driver: the tty driver in use
2010 * @index: the minor number
2011 * @p: output buffer of at least 7 bytes
2013 * Generate a name from a driver reference and write it to the output
2018 static void tty_line_name(struct tty_driver
*driver
, int index
, char *p
)
2020 sprintf(p
, "%s%d", driver
->name
, index
+ driver
->name_base
);
2024 * init_dev - initialise a tty device
2025 * @driver: tty driver we are opening a device on
2026 * @idx: device index
2027 * @tty: returned tty structure
2029 * Prepare a tty device. This may not be a "new" clean device but
2030 * could also be an active device. The pty drivers require special
2031 * handling because of this.
2034 * The function is called under the tty_mutex, which
2035 * protects us from the tty struct or driver itself going away.
2037 * On exit the tty device has the line discipline attached and
2038 * a reference count of 1. If a pair was created for pty/tty use
2039 * and the other was a pty master then it too has a reference count of 1.
2041 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
2042 * failed open. The new code protects the open with a mutex, so it's
2043 * really quite straightforward. The mutex locking can probably be
2044 * relaxed for the (most common) case of reopening a tty.
2047 static int init_dev(struct tty_driver
*driver
, int idx
,
2048 struct tty_struct
**ret_tty
)
2050 struct tty_struct
*tty
, *o_tty
;
2051 struct ktermios
*tp
, **tp_loc
, *o_tp
, **o_tp_loc
;
2052 struct ktermios
*ltp
, **ltp_loc
, *o_ltp
, **o_ltp_loc
;
2055 /* check whether we're reopening an existing tty */
2056 if (driver
->flags
& TTY_DRIVER_DEVPTS_MEM
) {
2057 tty
= devpts_get_tty(idx
);
2059 * If we don't have a tty here on a slave open, it's because
2060 * the master already started the close process and there's
2061 * no relation between devpts file and tty anymore.
2063 if (!tty
&& driver
->subtype
== PTY_TYPE_SLAVE
) {
2068 * It's safe from now on because init_dev() is called with
2069 * tty_mutex held and release_dev() won't change tty->count
2070 * or tty->flags without having to grab tty_mutex
2072 if (tty
&& driver
->subtype
== PTY_TYPE_MASTER
)
2075 tty
= driver
->ttys
[idx
];
2077 if (tty
) goto fast_track
;
2080 * First time open is complex, especially for PTY devices.
2081 * This code guarantees that either everything succeeds and the
2082 * TTY is ready for operation, or else the table slots are vacated
2083 * and the allocated memory released. (Except that the termios
2084 * and locked termios may be retained.)
2087 if (!try_module_get(driver
->owner
)) {
2096 tty
= alloc_tty_struct();
2099 initialize_tty_struct(tty
);
2100 tty
->driver
= driver
;
2102 tty_line_name(driver
, idx
, tty
->name
);
2104 if (driver
->flags
& TTY_DRIVER_DEVPTS_MEM
) {
2105 tp_loc
= &tty
->termios
;
2106 ltp_loc
= &tty
->termios_locked
;
2108 tp_loc
= &driver
->termios
[idx
];
2109 ltp_loc
= &driver
->termios_locked
[idx
];
2113 tp
= kmalloc(sizeof(struct ktermios
), GFP_KERNEL
);
2116 *tp
= driver
->init_termios
;
2120 ltp
= kzalloc(sizeof(struct ktermios
), GFP_KERNEL
);
2125 if (driver
->type
== TTY_DRIVER_TYPE_PTY
) {
2126 o_tty
= alloc_tty_struct();
2129 initialize_tty_struct(o_tty
);
2130 o_tty
->driver
= driver
->other
;
2132 tty_line_name(driver
->other
, idx
, o_tty
->name
);
2134 if (driver
->flags
& TTY_DRIVER_DEVPTS_MEM
) {
2135 o_tp_loc
= &o_tty
->termios
;
2136 o_ltp_loc
= &o_tty
->termios_locked
;
2138 o_tp_loc
= &driver
->other
->termios
[idx
];
2139 o_ltp_loc
= &driver
->other
->termios_locked
[idx
];
2143 o_tp
= kmalloc(sizeof(struct ktermios
), GFP_KERNEL
);
2146 *o_tp
= driver
->other
->init_termios
;
2150 o_ltp
= kzalloc(sizeof(struct ktermios
), GFP_KERNEL
);
2156 * Everything allocated ... set up the o_tty structure.
2158 if (!(driver
->other
->flags
& TTY_DRIVER_DEVPTS_MEM
))
2159 driver
->other
->ttys
[idx
] = o_tty
;
2164 o_tty
->termios
= *o_tp_loc
;
2165 o_tty
->termios_locked
= *o_ltp_loc
;
2166 driver
->other
->refcount
++;
2167 if (driver
->subtype
== PTY_TYPE_MASTER
)
2170 /* Establish the links in both directions */
2176 * All structures have been allocated, so now we install them.
2177 * Failures after this point use release_tty to clean up, so
2178 * there's no need to null out the local pointers.
2180 if (!(driver
->flags
& TTY_DRIVER_DEVPTS_MEM
))
2181 driver
->ttys
[idx
] = tty
;
2187 tty
->termios
= *tp_loc
;
2188 tty
->termios_locked
= *ltp_loc
;
2189 /* Compatibility until drivers always set this */
2190 tty
->termios
->c_ispeed
= tty_termios_input_baud_rate(tty
->termios
);
2191 tty
->termios
->c_ospeed
= tty_termios_baud_rate(tty
->termios
);
2196 * Structures all installed ... call the ldisc open routines.
2197 * If we fail here just call release_tty to clean up. No need
2198 * to decrement the use counts, as release_tty doesn't care.
2201 if (tty
->ldisc
.open
) {
2202 retval
= (tty
->ldisc
.open
)(tty
);
2204 goto release_mem_out
;
2206 if (o_tty
&& o_tty
->ldisc
.open
) {
2207 retval
= (o_tty
->ldisc
.open
)(o_tty
);
2209 if (tty
->ldisc
.close
)
2210 (tty
->ldisc
.close
)(tty
);
2211 goto release_mem_out
;
2213 tty_ldisc_enable(o_tty
);
2215 tty_ldisc_enable(tty
);
2219 * This fast open can be used if the tty is already open.
2220 * No memory is allocated, and the only failures are from
2221 * attempting to open a closing tty or attempting multiple
2222 * opens on a pty master.
2225 if (test_bit(TTY_CLOSING
, &tty
->flags
)) {
2229 if (driver
->type
== TTY_DRIVER_TYPE_PTY
&&
2230 driver
->subtype
== PTY_TYPE_MASTER
) {
2232 * special case for PTY masters: only one open permitted,
2233 * and the slave side open count is incremented as well.
2242 tty
->driver
= driver
; /* N.B. why do this every time?? */
2245 if (!test_bit(TTY_LDISC
, &tty
->flags
))
2246 printk(KERN_ERR
"init_dev but no ldisc\n");
2250 /* All paths come through here to release the mutex */
2254 /* Release locally allocated memory ... nothing placed in slots */
2258 free_tty_struct(o_tty
);
2261 free_tty_struct(tty
);
2264 module_put(driver
->owner
);
2268 /* call the tty release_tty routine to clean out this slot */
2270 if (printk_ratelimit())
2271 printk(KERN_INFO
"init_dev: ldisc open failed, "
2272 "clearing slot %d\n", idx
);
2273 release_tty(tty
, idx
);
2278 * release_one_tty - release tty structure memory
2280 * Releases memory associated with a tty structure, and clears out the
2281 * driver table slots. This function is called when a device is no longer
2282 * in use. It also gets called when setup of a device fails.
2285 * tty_mutex - sometimes only
2286 * takes the file list lock internally when working on the list
2287 * of ttys that the driver keeps.
2288 * FIXME: should we require tty_mutex is held here ??
2290 static void release_one_tty(struct tty_struct
*tty
, int idx
)
2292 int devpts
= tty
->driver
->flags
& TTY_DRIVER_DEVPTS_MEM
;
2293 struct ktermios
*tp
;
2296 tty
->driver
->ttys
[idx
] = NULL
;
2298 if (tty
->driver
->flags
& TTY_DRIVER_RESET_TERMIOS
) {
2301 tty
->driver
->termios
[idx
] = NULL
;
2304 tp
= tty
->termios_locked
;
2306 tty
->driver
->termios_locked
[idx
] = NULL
;
2312 tty
->driver
->refcount
--;
2315 list_del_init(&tty
->tty_files
);
2318 free_tty_struct(tty
);
2322 * release_tty - release tty structure memory
2324 * Release both @tty and a possible linked partner (think pty pair),
2325 * and decrement the refcount of the backing module.
2328 * tty_mutex - sometimes only
2329 * takes the file list lock internally when working on the list
2330 * of ttys that the driver keeps.
2331 * FIXME: should we require tty_mutex is held here ??
2333 static void release_tty(struct tty_struct
*tty
, int idx
)
2335 struct tty_driver
*driver
= tty
->driver
;
2338 release_one_tty(tty
->link
, idx
);
2339 release_one_tty(tty
, idx
);
2340 module_put(driver
->owner
);
2344 * Even releasing the tty structures is a tricky business.. We have
2345 * to be very careful that the structures are all released at the
2346 * same time, as interrupts might otherwise get the wrong pointers.
2348 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
2349 * lead to double frees or releasing memory still in use.
2351 static void release_dev(struct file
*filp
)
2353 struct tty_struct
*tty
, *o_tty
;
2354 int pty_master
, tty_closing
, o_tty_closing
, do_sleep
;
2358 unsigned long flags
;
2360 tty
= (struct tty_struct
*)filp
->private_data
;
2361 if (tty_paranoia_check(tty
, filp
->f_path
.dentry
->d_inode
,
2365 check_tty_count(tty
, "release_dev");
2367 tty_fasync(-1, filp
, 0);
2370 pty_master
= (tty
->driver
->type
== TTY_DRIVER_TYPE_PTY
&&
2371 tty
->driver
->subtype
== PTY_TYPE_MASTER
);
2372 devpts
= (tty
->driver
->flags
& TTY_DRIVER_DEVPTS_MEM
) != 0;
2375 #ifdef TTY_PARANOIA_CHECK
2376 if (idx
< 0 || idx
>= tty
->driver
->num
) {
2377 printk(KERN_DEBUG
"release_dev: bad idx when trying to "
2378 "free (%s)\n", tty
->name
);
2381 if (!(tty
->driver
->flags
& TTY_DRIVER_DEVPTS_MEM
)) {
2382 if (tty
!= tty
->driver
->ttys
[idx
]) {
2383 printk(KERN_DEBUG
"release_dev: driver.table[%d] not tty "
2384 "for (%s)\n", idx
, tty
->name
);
2387 if (tty
->termios
!= tty
->driver
->termios
[idx
]) {
2388 printk(KERN_DEBUG
"release_dev: driver.termios[%d] not termios "
2393 if (tty
->termios_locked
!= tty
->driver
->termios_locked
[idx
]) {
2394 printk(KERN_DEBUG
"release_dev: driver.termios_locked[%d] not "
2395 "termios_locked for (%s)\n",
2402 #ifdef TTY_DEBUG_HANGUP
2403 printk(KERN_DEBUG
"release_dev of %s (tty count=%d)...",
2404 tty_name(tty
, buf
), tty
->count
);
2407 #ifdef TTY_PARANOIA_CHECK
2408 if (tty
->driver
->other
&&
2409 !(tty
->driver
->flags
& TTY_DRIVER_DEVPTS_MEM
)) {
2410 if (o_tty
!= tty
->driver
->other
->ttys
[idx
]) {
2411 printk(KERN_DEBUG
"release_dev: other->table[%d] "
2412 "not o_tty for (%s)\n",
2416 if (o_tty
->termios
!= tty
->driver
->other
->termios
[idx
]) {
2417 printk(KERN_DEBUG
"release_dev: other->termios[%d] "
2418 "not o_termios for (%s)\n",
2422 if (o_tty
->termios_locked
!=
2423 tty
->driver
->other
->termios_locked
[idx
]) {
2424 printk(KERN_DEBUG
"release_dev: other->termios_locked["
2425 "%d] not o_termios_locked for (%s)\n",
2429 if (o_tty
->link
!= tty
) {
2430 printk(KERN_DEBUG
"release_dev: bad pty pointers\n");
2435 if (tty
->driver
->close
)
2436 tty
->driver
->close(tty
, filp
);
2439 * Sanity check: if tty->count is going to zero, there shouldn't be
2440 * any waiters on tty->read_wait or tty->write_wait. We test the
2441 * wait queues and kick everyone out _before_ actually starting to
2442 * close. This ensures that we won't block while releasing the tty
2445 * The test for the o_tty closing is necessary, since the master and
2446 * slave sides may close in any order. If the slave side closes out
2447 * first, its count will be one, since the master side holds an open.
2448 * Thus this test wouldn't be triggered at the time the slave closes,
2451 * Note that it's possible for the tty to be opened again while we're
2452 * flushing out waiters. By recalculating the closing flags before
2453 * each iteration we avoid any problems.
2456 /* Guard against races with tty->count changes elsewhere and
2457 opens on /dev/tty */
2459 mutex_lock(&tty_mutex
);
2460 tty_closing
= tty
->count
<= 1;
2461 o_tty_closing
= o_tty
&&
2462 (o_tty
->count
<= (pty_master
? 1 : 0));
2466 if (waitqueue_active(&tty
->read_wait
)) {
2467 wake_up(&tty
->read_wait
);
2470 if (waitqueue_active(&tty
->write_wait
)) {
2471 wake_up(&tty
->write_wait
);
2475 if (o_tty_closing
) {
2476 if (waitqueue_active(&o_tty
->read_wait
)) {
2477 wake_up(&o_tty
->read_wait
);
2480 if (waitqueue_active(&o_tty
->write_wait
)) {
2481 wake_up(&o_tty
->write_wait
);
2488 printk(KERN_WARNING
"release_dev: %s: read/write wait queue "
2489 "active!\n", tty_name(tty
, buf
));
2490 mutex_unlock(&tty_mutex
);
2495 * The closing flags are now consistent with the open counts on
2496 * both sides, and we've completed the last operation that could
2497 * block, so it's safe to proceed with closing.
2500 if (--o_tty
->count
< 0) {
2501 printk(KERN_WARNING
"release_dev: bad pty slave count "
2503 o_tty
->count
, tty_name(o_tty
, buf
));
2507 if (--tty
->count
< 0) {
2508 printk(KERN_WARNING
"release_dev: bad tty->count (%d) for %s\n",
2509 tty
->count
, tty_name(tty
, buf
));
2514 * We've decremented tty->count, so we need to remove this file
2515 * descriptor off the tty->tty_files list; this serves two
2517 * - check_tty_count sees the correct number of file descriptors
2518 * associated with this tty.
2519 * - do_tty_hangup no longer sees this file descriptor as
2520 * something that needs to be handled for hangups.
2523 filp
->private_data
= NULL
;
2526 * Perform some housekeeping before deciding whether to return.
2528 * Set the TTY_CLOSING flag if this was the last open. In the
2529 * case of a pty we may have to wait around for the other side
2530 * to close, and TTY_CLOSING makes sure we can't be reopened.
2533 set_bit(TTY_CLOSING
, &tty
->flags
);
2535 set_bit(TTY_CLOSING
, &o_tty
->flags
);
2538 * If _either_ side is closing, make sure there aren't any
2539 * processes that still think tty or o_tty is their controlling
2542 if (tty_closing
|| o_tty_closing
) {
2543 read_lock(&tasklist_lock
);
2544 session_clear_tty(tty
->session
);
2546 session_clear_tty(o_tty
->session
);
2547 read_unlock(&tasklist_lock
);
2550 mutex_unlock(&tty_mutex
);
2552 /* check whether both sides are closing ... */
2553 if (!tty_closing
|| (o_tty
&& !o_tty_closing
))
2556 #ifdef TTY_DEBUG_HANGUP
2557 printk(KERN_DEBUG
"freeing tty structure...");
2560 * Prevent flush_to_ldisc() from rescheduling the work for later. Then
2561 * kill any delayed work. As this is the final close it does not
2562 * race with the set_ldisc code path.
2564 clear_bit(TTY_LDISC
, &tty
->flags
);
2565 cancel_delayed_work(&tty
->buf
.work
);
2568 * Wait for ->hangup_work and ->buf.work handlers to terminate
2571 flush_scheduled_work();
2574 * Wait for any short term users (we know they are just driver
2575 * side waiters as the file is closing so user count on the file
2578 spin_lock_irqsave(&tty_ldisc_lock
, flags
);
2579 while (tty
->ldisc
.refcount
) {
2580 spin_unlock_irqrestore(&tty_ldisc_lock
, flags
);
2581 wait_event(tty_ldisc_wait
, tty
->ldisc
.refcount
== 0);
2582 spin_lock_irqsave(&tty_ldisc_lock
, flags
);
2584 spin_unlock_irqrestore(&tty_ldisc_lock
, flags
);
2586 * Shutdown the current line discipline, and reset it to N_TTY.
2587 * N.B. why reset ldisc when we're releasing the memory??
2589 * FIXME: this MUST get fixed for the new reflocking
2591 if (tty
->ldisc
.close
)
2592 (tty
->ldisc
.close
)(tty
);
2593 tty_ldisc_put(tty
->ldisc
.num
);
2596 * Switch the line discipline back
2598 tty_ldisc_assign(tty
, tty_ldisc_get(N_TTY
));
2599 tty_set_termios_ldisc(tty
, N_TTY
);
2601 /* FIXME: could o_tty be in setldisc here ? */
2602 clear_bit(TTY_LDISC
, &o_tty
->flags
);
2603 if (o_tty
->ldisc
.close
)
2604 (o_tty
->ldisc
.close
)(o_tty
);
2605 tty_ldisc_put(o_tty
->ldisc
.num
);
2606 tty_ldisc_assign(o_tty
, tty_ldisc_get(N_TTY
));
2607 tty_set_termios_ldisc(o_tty
, N_TTY
);
2610 * The release_tty function takes care of the details of clearing
2611 * the slots and preserving the termios structure.
2613 release_tty(tty
, idx
);
2615 #ifdef CONFIG_UNIX98_PTYS
2616 /* Make this pty number available for reallocation */
2618 mutex_lock(&allocated_ptys_lock
);
2619 idr_remove(&allocated_ptys
, idx
);
2620 mutex_unlock(&allocated_ptys_lock
);
2627 * tty_open - open a tty device
2628 * @inode: inode of device file
2629 * @filp: file pointer to tty
2631 * tty_open and tty_release keep up the tty count that contains the
2632 * number of opens done on a tty. We cannot use the inode-count, as
2633 * different inodes might point to the same tty.
2635 * Open-counting is needed for pty masters, as well as for keeping
2636 * track of serial lines: DTR is dropped when the last close happens.
2637 * (This is not done solely through tty->count, now. - Ted 1/27/92)
2639 * The termios state of a pty is reset on first open so that
2640 * settings don't persist across reuse.
2642 * Locking: tty_mutex protects tty, get_tty_driver and init_dev work.
2643 * tty->count should protect the rest.
2644 * ->siglock protects ->signal/->sighand
2647 static int tty_open(struct inode
*inode
, struct file
*filp
)
2649 struct tty_struct
*tty
;
2651 struct tty_driver
*driver
;
2653 dev_t device
= inode
->i_rdev
;
2654 unsigned short saved_flags
= filp
->f_flags
;
2656 nonseekable_open(inode
, filp
);
2659 noctty
= filp
->f_flags
& O_NOCTTY
;
2663 mutex_lock(&tty_mutex
);
2665 if (device
== MKDEV(TTYAUX_MAJOR
, 0)) {
2666 tty
= get_current_tty();
2668 mutex_unlock(&tty_mutex
);
2671 driver
= tty
->driver
;
2673 filp
->f_flags
|= O_NONBLOCK
; /* Don't let /dev/tty block */
2678 if (device
== MKDEV(TTY_MAJOR
, 0)) {
2679 extern struct tty_driver
*console_driver
;
2680 driver
= console_driver
;
2686 if (device
== MKDEV(TTYAUX_MAJOR
, 1)) {
2687 driver
= console_device(&index
);
2689 /* Don't let /dev/console block */
2690 filp
->f_flags
|= O_NONBLOCK
;
2694 mutex_unlock(&tty_mutex
);
2698 driver
= get_tty_driver(device
, &index
);
2700 mutex_unlock(&tty_mutex
);
2704 retval
= init_dev(driver
, index
, &tty
);
2705 mutex_unlock(&tty_mutex
);
2709 filp
->private_data
= tty
;
2710 file_move(filp
, &tty
->tty_files
);
2711 check_tty_count(tty
, "tty_open");
2712 if (tty
->driver
->type
== TTY_DRIVER_TYPE_PTY
&&
2713 tty
->driver
->subtype
== PTY_TYPE_MASTER
)
2715 #ifdef TTY_DEBUG_HANGUP
2716 printk(KERN_DEBUG
"opening %s...", tty
->name
);
2719 if (tty
->driver
->open
)
2720 retval
= tty
->driver
->open(tty
, filp
);
2724 filp
->f_flags
= saved_flags
;
2726 if (!retval
&& test_bit(TTY_EXCLUSIVE
, &tty
->flags
) &&
2727 !capable(CAP_SYS_ADMIN
))
2731 #ifdef TTY_DEBUG_HANGUP
2732 printk(KERN_DEBUG
"error %d in opening %s...", retval
,
2736 if (retval
!= -ERESTARTSYS
)
2738 if (signal_pending(current
))
2742 * Need to reset f_op in case a hangup happened.
2744 if (filp
->f_op
== &hung_up_tty_fops
)
2745 filp
->f_op
= &tty_fops
;
2749 mutex_lock(&tty_mutex
);
2750 spin_lock_irq(¤t
->sighand
->siglock
);
2752 current
->signal
->leader
&&
2753 !current
->signal
->tty
&&
2754 tty
->session
== NULL
)
2755 __proc_set_tty(current
, tty
);
2756 spin_unlock_irq(¤t
->sighand
->siglock
);
2757 mutex_unlock(&tty_mutex
);
2758 tty_audit_opening();
2762 #ifdef CONFIG_UNIX98_PTYS
2764 * ptmx_open - open a unix 98 pty master
2765 * @inode: inode of device file
2766 * @filp: file pointer to tty
2768 * Allocate a unix98 pty master device from the ptmx driver.
2770 * Locking: tty_mutex protects theinit_dev work. tty->count should
2772 * allocated_ptys_lock handles the list of free pty numbers
2775 static int ptmx_open(struct inode
*inode
, struct file
*filp
)
2777 struct tty_struct
*tty
;
2782 nonseekable_open(inode
, filp
);
2784 /* find a device that is not in use. */
2785 mutex_lock(&allocated_ptys_lock
);
2786 if (!idr_pre_get(&allocated_ptys
, GFP_KERNEL
)) {
2787 mutex_unlock(&allocated_ptys_lock
);
2790 idr_ret
= idr_get_new(&allocated_ptys
, NULL
, &index
);
2792 mutex_unlock(&allocated_ptys_lock
);
2793 if (idr_ret
== -EAGAIN
)
2797 if (index
>= pty_limit
) {
2798 idr_remove(&allocated_ptys
, index
);
2799 mutex_unlock(&allocated_ptys_lock
);
2802 mutex_unlock(&allocated_ptys_lock
);
2804 mutex_lock(&tty_mutex
);
2805 retval
= init_dev(ptm_driver
, index
, &tty
);
2806 mutex_unlock(&tty_mutex
);
2811 set_bit(TTY_PTY_LOCK
, &tty
->flags
); /* LOCK THE SLAVE */
2812 filp
->private_data
= tty
;
2813 file_move(filp
, &tty
->tty_files
);
2816 if (devpts_pty_new(tty
->link
))
2819 check_tty_count(tty
, "tty_open");
2820 retval
= ptm_driver
->open(tty
, filp
);
2822 tty_audit_opening();
2829 mutex_lock(&allocated_ptys_lock
);
2830 idr_remove(&allocated_ptys
, index
);
2831 mutex_unlock(&allocated_ptys_lock
);
2837 * tty_release - vfs callback for close
2838 * @inode: inode of tty
2839 * @filp: file pointer for handle to tty
2841 * Called the last time each file handle is closed that references
2842 * this tty. There may however be several such references.
2845 * Takes bkl. See release_dev
2848 static int tty_release(struct inode
*inode
, struct file
*filp
)
2857 * tty_poll - check tty status
2858 * @filp: file being polled
2859 * @wait: poll wait structures to update
2861 * Call the line discipline polling method to obtain the poll
2862 * status of the device.
2864 * Locking: locks called line discipline but ldisc poll method
2865 * may be re-entered freely by other callers.
2868 static unsigned int tty_poll(struct file
*filp
, poll_table
*wait
)
2870 struct tty_struct
*tty
;
2871 struct tty_ldisc
*ld
;
2874 tty
= (struct tty_struct
*)filp
->private_data
;
2875 if (tty_paranoia_check(tty
, filp
->f_path
.dentry
->d_inode
, "tty_poll"))
2878 ld
= tty_ldisc_ref_wait(tty
);
2880 ret
= (ld
->poll
)(tty
, filp
, wait
);
2881 tty_ldisc_deref(ld
);
2885 static int tty_fasync(int fd
, struct file
*filp
, int on
)
2887 struct tty_struct
*tty
;
2890 tty
= (struct tty_struct
*)filp
->private_data
;
2891 if (tty_paranoia_check(tty
, filp
->f_path
.dentry
->d_inode
, "tty_fasync"))
2894 retval
= fasync_helper(fd
, filp
, on
, &tty
->fasync
);
2901 if (!waitqueue_active(&tty
->read_wait
))
2902 tty
->minimum_to_wake
= 1;
2905 type
= PIDTYPE_PGID
;
2907 pid
= task_pid(current
);
2910 retval
= __f_setown(filp
, pid
, type
, 0);
2914 if (!tty
->fasync
&& !waitqueue_active(&tty
->read_wait
))
2915 tty
->minimum_to_wake
= N_TTY_BUF_SIZE
;
2921 * tiocsti - fake input character
2922 * @tty: tty to fake input into
2923 * @p: pointer to character
2925 * Fake input to a tty device. Does the necessary locking and
2928 * FIXME: does not honour flow control ??
2931 * Called functions take tty_ldisc_lock
2932 * current->signal->tty check is safe without locks
2934 * FIXME: may race normal receive processing
2937 static int tiocsti(struct tty_struct
*tty
, char __user
*p
)
2940 struct tty_ldisc
*ld
;
2942 if ((current
->signal
->tty
!= tty
) && !capable(CAP_SYS_ADMIN
))
2944 if (get_user(ch
, p
))
2946 ld
= tty_ldisc_ref_wait(tty
);
2947 ld
->receive_buf(tty
, &ch
, &mbz
, 1);
2948 tty_ldisc_deref(ld
);
2953 * tiocgwinsz - implement window query ioctl
2955 * @arg: user buffer for result
2957 * Copies the kernel idea of the window size into the user buffer.
2959 * Locking: tty->termios_mutex is taken to ensure the winsize data
2963 static int tiocgwinsz(struct tty_struct
*tty
, struct winsize __user
*arg
)
2967 mutex_lock(&tty
->termios_mutex
);
2968 err
= copy_to_user(arg
, &tty
->winsize
, sizeof(*arg
));
2969 mutex_unlock(&tty
->termios_mutex
);
2971 return err
? -EFAULT
: 0;
2975 * tiocswinsz - implement window size set ioctl
2977 * @arg: user buffer for result
2979 * Copies the user idea of the window size to the kernel. Traditionally
2980 * this is just advisory information but for the Linux console it
2981 * actually has driver level meaning and triggers a VC resize.
2984 * Called function use the console_sem is used to ensure we do
2985 * not try and resize the console twice at once.
2986 * The tty->termios_mutex is used to ensure we don't double
2987 * resize and get confused. Lock order - tty->termios_mutex before
2991 static int tiocswinsz(struct tty_struct
*tty
, struct tty_struct
*real_tty
,
2992 struct winsize __user
*arg
)
2994 struct winsize tmp_ws
;
2996 if (copy_from_user(&tmp_ws
, arg
, sizeof(*arg
)))
2999 mutex_lock(&tty
->termios_mutex
);
3000 if (!memcmp(&tmp_ws
, &tty
->winsize
, sizeof(*arg
)))
3004 if (tty
->driver
->type
== TTY_DRIVER_TYPE_CONSOLE
) {
3005 if (vc_lock_resize(tty
->driver_data
, tmp_ws
.ws_col
,
3007 mutex_unlock(&tty
->termios_mutex
);
3013 kill_pgrp(tty
->pgrp
, SIGWINCH
, 1);
3014 if ((real_tty
->pgrp
!= tty
->pgrp
) && real_tty
->pgrp
)
3015 kill_pgrp(real_tty
->pgrp
, SIGWINCH
, 1);
3016 tty
->winsize
= tmp_ws
;
3017 real_tty
->winsize
= tmp_ws
;
3019 mutex_unlock(&tty
->termios_mutex
);
3024 * tioccons - allow admin to move logical console
3025 * @file: the file to become console
3027 * Allow the adminstrator to move the redirected console device
3029 * Locking: uses redirect_lock to guard the redirect information
3032 static int tioccons(struct file
*file
)
3034 if (!capable(CAP_SYS_ADMIN
))
3036 if (file
->f_op
->write
== redirected_tty_write
) {
3038 spin_lock(&redirect_lock
);
3041 spin_unlock(&redirect_lock
);
3046 spin_lock(&redirect_lock
);
3048 spin_unlock(&redirect_lock
);
3053 spin_unlock(&redirect_lock
);
3058 * fionbio - non blocking ioctl
3059 * @file: file to set blocking value
3060 * @p: user parameter
3062 * Historical tty interfaces had a blocking control ioctl before
3063 * the generic functionality existed. This piece of history is preserved
3064 * in the expected tty API of posix OS's.
3066 * Locking: none, the open fle handle ensures it won't go away.
3069 static int fionbio(struct file
*file
, int __user
*p
)
3073 if (get_user(nonblock
, p
))
3077 file
->f_flags
|= O_NONBLOCK
;
3079 file
->f_flags
&= ~O_NONBLOCK
;
3084 * tiocsctty - set controlling tty
3085 * @tty: tty structure
3086 * @arg: user argument
3088 * This ioctl is used to manage job control. It permits a session
3089 * leader to set this tty as the controlling tty for the session.
3092 * Takes tty_mutex() to protect tty instance
3093 * Takes tasklist_lock internally to walk sessions
3094 * Takes ->siglock() when updating signal->tty
3097 static int tiocsctty(struct tty_struct
*tty
, int arg
)
3100 if (current
->signal
->leader
&& (task_session(current
) == tty
->session
))
3103 mutex_lock(&tty_mutex
);
3105 * The process must be a session leader and
3106 * not have a controlling tty already.
3108 if (!current
->signal
->leader
|| current
->signal
->tty
) {
3115 * This tty is already the controlling
3116 * tty for another session group!
3118 if (arg
== 1 && capable(CAP_SYS_ADMIN
)) {
3122 read_lock(&tasklist_lock
);
3123 session_clear_tty(tty
->session
);
3124 read_unlock(&tasklist_lock
);
3130 proc_set_tty(current
, tty
);
3132 mutex_unlock(&tty_mutex
);
3137 * tiocgpgrp - get process group
3138 * @tty: tty passed by user
3139 * @real_tty: tty side of the tty pased by the user if a pty else the tty
3142 * Obtain the process group of the tty. If there is no process group
3145 * Locking: none. Reference to current->signal->tty is safe.
3148 static int tiocgpgrp(struct tty_struct
*tty
, struct tty_struct
*real_tty
, pid_t __user
*p
)
3151 * (tty == real_tty) is a cheap way of
3152 * testing if the tty is NOT a master pty.
3154 if (tty
== real_tty
&& current
->signal
->tty
!= real_tty
)
3156 return put_user(pid_vnr(real_tty
->pgrp
), p
);
3160 * tiocspgrp - attempt to set process group
3161 * @tty: tty passed by user
3162 * @real_tty: tty side device matching tty passed by user
3165 * Set the process group of the tty to the session passed. Only
3166 * permitted where the tty session is our session.
3171 static int tiocspgrp(struct tty_struct
*tty
, struct tty_struct
*real_tty
, pid_t __user
*p
)
3175 int retval
= tty_check_change(real_tty
);
3181 if (!current
->signal
->tty
||
3182 (current
->signal
->tty
!= real_tty
) ||
3183 (real_tty
->session
!= task_session(current
)))
3185 if (get_user(pgrp_nr
, p
))
3190 pgrp
= find_vpid(pgrp_nr
);
3195 if (session_of_pgrp(pgrp
) != task_session(current
))
3198 put_pid(real_tty
->pgrp
);
3199 real_tty
->pgrp
= get_pid(pgrp
);
3206 * tiocgsid - get session id
3207 * @tty: tty passed by user
3208 * @real_tty: tty side of the tty pased by the user if a pty else the tty
3209 * @p: pointer to returned session id
3211 * Obtain the session id of the tty. If there is no session
3214 * Locking: none. Reference to current->signal->tty is safe.
3217 static int tiocgsid(struct tty_struct
*tty
, struct tty_struct
*real_tty
, pid_t __user
*p
)
3220 * (tty == real_tty) is a cheap way of
3221 * testing if the tty is NOT a master pty.
3223 if (tty
== real_tty
&& current
->signal
->tty
!= real_tty
)
3225 if (!real_tty
->session
)
3227 return put_user(pid_vnr(real_tty
->session
), p
);
3231 * tiocsetd - set line discipline
3233 * @p: pointer to user data
3235 * Set the line discipline according to user request.
3237 * Locking: see tty_set_ldisc, this function is just a helper
3240 static int tiocsetd(struct tty_struct
*tty
, int __user
*p
)
3244 if (get_user(ldisc
, p
))
3246 return tty_set_ldisc(tty
, ldisc
);
3250 * send_break - performed time break
3251 * @tty: device to break on
3252 * @duration: timeout in mS
3254 * Perform a timed break on hardware that lacks its own driver level
3255 * timed break functionality.
3258 * atomic_write_lock serializes
3262 static int send_break(struct tty_struct
*tty
, unsigned int duration
)
3264 if (tty_write_lock(tty
, 0) < 0)
3266 tty
->driver
->break_ctl(tty
, -1);
3267 if (!signal_pending(current
))
3268 msleep_interruptible(duration
);
3269 tty
->driver
->break_ctl(tty
, 0);
3270 tty_write_unlock(tty
);
3271 if (signal_pending(current
))
3277 * tiocmget - get modem status
3279 * @file: user file pointer
3280 * @p: pointer to result
3282 * Obtain the modem status bits from the tty driver if the feature
3283 * is supported. Return -EINVAL if it is not available.
3285 * Locking: none (up to the driver)
3288 static int tty_tiocmget(struct tty_struct
*tty
, struct file
*file
, int __user
*p
)
3290 int retval
= -EINVAL
;
3292 if (tty
->driver
->tiocmget
) {
3293 retval
= tty
->driver
->tiocmget(tty
, file
);
3296 retval
= put_user(retval
, p
);
3302 * tiocmset - set modem status
3304 * @file: user file pointer
3305 * @cmd: command - clear bits, set bits or set all
3306 * @p: pointer to desired bits
3308 * Set the modem status bits from the tty driver if the feature
3309 * is supported. Return -EINVAL if it is not available.
3311 * Locking: none (up to the driver)
3314 static int tty_tiocmset(struct tty_struct
*tty
, struct file
*file
, unsigned int cmd
,
3317 int retval
= -EINVAL
;
3319 if (tty
->driver
->tiocmset
) {
3320 unsigned int set
, clear
, val
;
3322 retval
= get_user(val
, p
);
3340 set
&= TIOCM_DTR
|TIOCM_RTS
|TIOCM_OUT1
|TIOCM_OUT2
|TIOCM_LOOP
;
3341 clear
&= TIOCM_DTR
|TIOCM_RTS
|TIOCM_OUT1
|TIOCM_OUT2
|TIOCM_LOOP
;
3343 retval
= tty
->driver
->tiocmset(tty
, file
, set
, clear
);
3349 * Split this up, as gcc can choke on it otherwise..
3351 int tty_ioctl(struct inode
*inode
, struct file
*file
,
3352 unsigned int cmd
, unsigned long arg
)
3354 struct tty_struct
*tty
, *real_tty
;
3355 void __user
*p
= (void __user
*)arg
;
3357 struct tty_ldisc
*ld
;
3359 tty
= (struct tty_struct
*)file
->private_data
;
3360 if (tty_paranoia_check(tty
, inode
, "tty_ioctl"))
3363 /* CHECKME: is this safe as one end closes ? */
3366 if (tty
->driver
->type
== TTY_DRIVER_TYPE_PTY
&&
3367 tty
->driver
->subtype
== PTY_TYPE_MASTER
)
3368 real_tty
= tty
->link
;
3371 * Break handling by driver
3373 if (!tty
->driver
->break_ctl
) {
3377 if (tty
->driver
->ioctl
)
3378 return tty
->driver
->ioctl(tty
, file
, cmd
, arg
);
3381 /* These two ioctl's always return success; even if */
3382 /* the driver doesn't support them. */
3385 if (!tty
->driver
->ioctl
)
3387 retval
= tty
->driver
->ioctl(tty
, file
, cmd
, arg
);
3388 if (retval
== -ENOIOCTLCMD
)
3395 * Factor out some common prep work
3403 retval
= tty_check_change(tty
);
3406 if (cmd
!= TIOCCBRK
) {
3407 tty_wait_until_sent(tty
, 0);
3408 if (signal_pending(current
))
3416 return tiocsti(tty
, p
);
3418 return tiocgwinsz(tty
, p
);
3420 return tiocswinsz(tty
, real_tty
, p
);
3422 return real_tty
!= tty
? -EINVAL
: tioccons(file
);
3424 return fionbio(file
, p
);
3426 set_bit(TTY_EXCLUSIVE
, &tty
->flags
);
3429 clear_bit(TTY_EXCLUSIVE
, &tty
->flags
);
3432 if (current
->signal
->tty
!= tty
)
3437 return tiocsctty(tty
, arg
);
3439 return tiocgpgrp(tty
, real_tty
, p
);
3441 return tiocspgrp(tty
, real_tty
, p
);
3443 return tiocgsid(tty
, real_tty
, p
);
3445 /* FIXME: check this is ok */
3446 return put_user(tty
->ldisc
.num
, (int __user
*)p
);
3448 return tiocsetd(tty
, p
);
3451 return tioclinux(tty
, arg
);
3456 case TIOCSBRK
: /* Turn break on, unconditionally */
3457 tty
->driver
->break_ctl(tty
, -1);
3460 case TIOCCBRK
: /* Turn break off, unconditionally */
3461 tty
->driver
->break_ctl(tty
, 0);
3463 case TCSBRK
: /* SVID version: non-zero arg --> no break */
3464 /* non-zero arg means wait for all output data
3465 * to be sent (performed above) but don't send break.
3466 * This is used by the tcdrain() termios function.
3469 return send_break(tty
, 250);
3471 case TCSBRKP
: /* support for POSIX tcsendbreak() */
3472 return send_break(tty
, arg
? arg
*100 : 250);
3475 return tty_tiocmget(tty
, file
, p
);
3479 return tty_tiocmset(tty
, file
, cmd
, p
);
3484 /* flush tty buffer and allow ldisc to process ioctl */
3485 tty_buffer_flush(tty
);
3490 if (tty
->driver
->ioctl
) {
3491 retval
= (tty
->driver
->ioctl
)(tty
, file
, cmd
, arg
);
3492 if (retval
!= -ENOIOCTLCMD
)
3495 ld
= tty_ldisc_ref_wait(tty
);
3498 retval
= ld
->ioctl(tty
, file
, cmd
, arg
);
3499 if (retval
== -ENOIOCTLCMD
)
3502 tty_ldisc_deref(ld
);
3506 #ifdef CONFIG_COMPAT
3507 static long tty_compat_ioctl(struct file
*file
, unsigned int cmd
,
3510 struct inode
*inode
= file
->f_dentry
->d_inode
;
3511 struct tty_struct
*tty
= file
->private_data
;
3512 struct tty_ldisc
*ld
;
3513 int retval
= -ENOIOCTLCMD
;
3515 if (tty_paranoia_check(tty
, inode
, "tty_ioctl"))
3518 if (tty
->driver
->compat_ioctl
) {
3519 retval
= (tty
->driver
->compat_ioctl
)(tty
, file
, cmd
, arg
);
3520 if (retval
!= -ENOIOCTLCMD
)
3524 ld
= tty_ldisc_ref_wait(tty
);
3525 if (ld
->compat_ioctl
)
3526 retval
= ld
->compat_ioctl(tty
, file
, cmd
, arg
);
3527 tty_ldisc_deref(ld
);
3534 * This implements the "Secure Attention Key" --- the idea is to
3535 * prevent trojan horses by killing all processes associated with this
3536 * tty when the user hits the "Secure Attention Key". Required for
3537 * super-paranoid applications --- see the Orange Book for more details.
3539 * This code could be nicer; ideally it should send a HUP, wait a few
3540 * seconds, then send a INT, and then a KILL signal. But you then
3541 * have to coordinate with the init process, since all processes associated
3542 * with the current tty must be dead before the new getty is allowed
3545 * Now, if it would be correct ;-/ The current code has a nasty hole -
3546 * it doesn't catch files in flight. We may send the descriptor to ourselves
3547 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
3549 * Nasty bug: do_SAK is being called in interrupt context. This can
3550 * deadlock. We punt it up to process context. AKPM - 16Mar2001
3552 void __do_SAK(struct tty_struct
*tty
)
3557 struct task_struct
*g
, *p
;
3558 struct pid
*session
;
3561 struct fdtable
*fdt
;
3565 session
= tty
->session
;
3567 tty_ldisc_flush(tty
);
3569 if (tty
->driver
->flush_buffer
)
3570 tty
->driver
->flush_buffer(tty
);
3572 read_lock(&tasklist_lock
);
3573 /* Kill the entire session */
3574 do_each_pid_task(session
, PIDTYPE_SID
, p
) {
3575 printk(KERN_NOTICE
"SAK: killed process %d"
3576 " (%s): task_session_nr(p)==tty->session\n",
3577 task_pid_nr(p
), p
->comm
);
3578 send_sig(SIGKILL
, p
, 1);
3579 } while_each_pid_task(session
, PIDTYPE_SID
, p
);
3580 /* Now kill any processes that happen to have the
3583 do_each_thread(g
, p
) {
3584 if (p
->signal
->tty
== tty
) {
3585 printk(KERN_NOTICE
"SAK: killed process %d"
3586 " (%s): task_session_nr(p)==tty->session\n",
3587 task_pid_nr(p
), p
->comm
);
3588 send_sig(SIGKILL
, p
, 1);
3594 * We don't take a ref to the file, so we must
3595 * hold ->file_lock instead.
3597 spin_lock(&p
->files
->file_lock
);
3598 fdt
= files_fdtable(p
->files
);
3599 for (i
= 0; i
< fdt
->max_fds
; i
++) {
3600 filp
= fcheck_files(p
->files
, i
);
3603 if (filp
->f_op
->read
== tty_read
&&
3604 filp
->private_data
== tty
) {
3605 printk(KERN_NOTICE
"SAK: killed process %d"
3606 " (%s): fd#%d opened to the tty\n",
3607 task_pid_nr(p
), p
->comm
, i
);
3608 force_sig(SIGKILL
, p
);
3612 spin_unlock(&p
->files
->file_lock
);
3615 } while_each_thread(g
, p
);
3616 read_unlock(&tasklist_lock
);
3620 static void do_SAK_work(struct work_struct
*work
)
3622 struct tty_struct
*tty
=
3623 container_of(work
, struct tty_struct
, SAK_work
);
3628 * The tq handling here is a little racy - tty->SAK_work may already be queued.
3629 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
3630 * the values which we write to it will be identical to the values which it
3631 * already has. --akpm
3633 void do_SAK(struct tty_struct
*tty
)
3637 schedule_work(&tty
->SAK_work
);
3640 EXPORT_SYMBOL(do_SAK
);
3644 * @work: tty structure passed from work queue.
3646 * This routine is called out of the software interrupt to flush data
3647 * from the buffer chain to the line discipline.
3649 * Locking: holds tty->buf.lock to guard buffer list. Drops the lock
3650 * while invoking the line discipline receive_buf method. The
3651 * receive_buf method is single threaded for each tty instance.
3654 static void flush_to_ldisc(struct work_struct
*work
)
3656 struct tty_struct
*tty
=
3657 container_of(work
, struct tty_struct
, buf
.work
.work
);
3658 unsigned long flags
;
3659 struct tty_ldisc
*disc
;
3660 struct tty_buffer
*tbuf
, *head
;
3662 unsigned char *flag_buf
;
3664 disc
= tty_ldisc_ref(tty
);
3665 if (disc
== NULL
) /* !TTY_LDISC */
3668 spin_lock_irqsave(&tty
->buf
.lock
, flags
);
3669 /* So we know a flush is running */
3670 set_bit(TTY_FLUSHING
, &tty
->flags
);
3671 head
= tty
->buf
.head
;
3673 tty
->buf
.head
= NULL
;
3675 int count
= head
->commit
- head
->read
;
3677 if (head
->next
== NULL
)
3681 tty_buffer_free(tty
, tbuf
);
3684 /* Ldisc or user is trying to flush the buffers
3685 we are feeding to the ldisc, stop feeding the
3686 line discipline as we want to empty the queue */
3687 if (test_bit(TTY_FLUSHPENDING
, &tty
->flags
))
3689 if (!tty
->receive_room
) {
3690 schedule_delayed_work(&tty
->buf
.work
, 1);
3693 if (count
> tty
->receive_room
)
3694 count
= tty
->receive_room
;
3695 char_buf
= head
->char_buf_ptr
+ head
->read
;
3696 flag_buf
= head
->flag_buf_ptr
+ head
->read
;
3697 head
->read
+= count
;
3698 spin_unlock_irqrestore(&tty
->buf
.lock
, flags
);
3699 disc
->receive_buf(tty
, char_buf
, flag_buf
, count
);
3700 spin_lock_irqsave(&tty
->buf
.lock
, flags
);
3702 /* Restore the queue head */
3703 tty
->buf
.head
= head
;
3705 /* We may have a deferred request to flush the input buffer,
3706 if so pull the chain under the lock and empty the queue */
3707 if (test_bit(TTY_FLUSHPENDING
, &tty
->flags
)) {
3708 __tty_buffer_flush(tty
);
3709 clear_bit(TTY_FLUSHPENDING
, &tty
->flags
);
3710 wake_up(&tty
->read_wait
);
3712 clear_bit(TTY_FLUSHING
, &tty
->flags
);
3713 spin_unlock_irqrestore(&tty
->buf
.lock
, flags
);
3715 tty_ldisc_deref(disc
);
3719 * tty_flip_buffer_push - terminal
3722 * Queue a push of the terminal flip buffers to the line discipline. This
3723 * function must not be called from IRQ context if tty->low_latency is set.
3725 * In the event of the queue being busy for flipping the work will be
3726 * held off and retried later.
3728 * Locking: tty buffer lock. Driver locks in low latency mode.
3731 void tty_flip_buffer_push(struct tty_struct
*tty
)
3733 unsigned long flags
;
3734 spin_lock_irqsave(&tty
->buf
.lock
, flags
);
3735 if (tty
->buf
.tail
!= NULL
)
3736 tty
->buf
.tail
->commit
= tty
->buf
.tail
->used
;
3737 spin_unlock_irqrestore(&tty
->buf
.lock
, flags
);
3739 if (tty
->low_latency
)
3740 flush_to_ldisc(&tty
->buf
.work
.work
);
3742 schedule_delayed_work(&tty
->buf
.work
, 1);
3745 EXPORT_SYMBOL(tty_flip_buffer_push
);
3749 * initialize_tty_struct
3750 * @tty: tty to initialize
3752 * This subroutine initializes a tty structure that has been newly
3755 * Locking: none - tty in question must not be exposed at this point
3758 static void initialize_tty_struct(struct tty_struct
*tty
)
3760 memset(tty
, 0, sizeof(struct tty_struct
));
3761 tty
->magic
= TTY_MAGIC
;
3762 tty_ldisc_assign(tty
, tty_ldisc_get(N_TTY
));
3763 tty
->session
= NULL
;
3765 tty
->overrun_time
= jiffies
;
3766 tty
->buf
.head
= tty
->buf
.tail
= NULL
;
3767 tty_buffer_init(tty
);
3768 INIT_DELAYED_WORK(&tty
->buf
.work
, flush_to_ldisc
);
3769 mutex_init(&tty
->termios_mutex
);
3770 init_waitqueue_head(&tty
->write_wait
);
3771 init_waitqueue_head(&tty
->read_wait
);
3772 INIT_WORK(&tty
->hangup_work
, do_tty_hangup
);
3773 mutex_init(&tty
->atomic_read_lock
);
3774 mutex_init(&tty
->atomic_write_lock
);
3775 spin_lock_init(&tty
->read_lock
);
3776 INIT_LIST_HEAD(&tty
->tty_files
);
3777 INIT_WORK(&tty
->SAK_work
, do_SAK_work
);
3781 * The default put_char routine if the driver did not define one.
3784 static void tty_default_put_char(struct tty_struct
*tty
, unsigned char ch
)
3786 tty
->driver
->write(tty
, &ch
, 1);
3789 static struct class *tty_class
;
3792 * tty_register_device - register a tty device
3793 * @driver: the tty driver that describes the tty device
3794 * @index: the index in the tty driver for this tty device
3795 * @device: a struct device that is associated with this tty device.
3796 * This field is optional, if there is no known struct device
3797 * for this tty device it can be set to NULL safely.
3799 * Returns a pointer to the struct device for this tty device
3800 * (or ERR_PTR(-EFOO) on error).
3802 * This call is required to be made to register an individual tty device
3803 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3804 * that bit is not set, this function should not be called by a tty
3810 struct device
*tty_register_device(struct tty_driver
*driver
, unsigned index
,
3811 struct device
*device
)
3814 dev_t dev
= MKDEV(driver
->major
, driver
->minor_start
) + index
;
3816 if (index
>= driver
->num
) {
3817 printk(KERN_ERR
"Attempt to register invalid tty line number "
3819 return ERR_PTR(-EINVAL
);
3822 if (driver
->type
== TTY_DRIVER_TYPE_PTY
)
3823 pty_line_name(driver
, index
, name
);
3825 tty_line_name(driver
, index
, name
);
3827 return device_create(tty_class
, device
, dev
, name
);
3831 * tty_unregister_device - unregister a tty device
3832 * @driver: the tty driver that describes the tty device
3833 * @index: the index in the tty driver for this tty device
3835 * If a tty device is registered with a call to tty_register_device() then
3836 * this function must be called when the tty device is gone.
3841 void tty_unregister_device(struct tty_driver
*driver
, unsigned index
)
3843 device_destroy(tty_class
,
3844 MKDEV(driver
->major
, driver
->minor_start
) + index
);
3847 EXPORT_SYMBOL(tty_register_device
);
3848 EXPORT_SYMBOL(tty_unregister_device
);
3850 struct tty_driver
*alloc_tty_driver(int lines
)
3852 struct tty_driver
*driver
;
3854 driver
= kzalloc(sizeof(struct tty_driver
), GFP_KERNEL
);
3856 driver
->magic
= TTY_DRIVER_MAGIC
;
3857 driver
->num
= lines
;
3858 /* later we'll move allocation of tables here */
3863 void put_tty_driver(struct tty_driver
*driver
)
3868 void tty_set_operations(struct tty_driver
*driver
,
3869 const struct tty_operations
*op
)
3871 driver
->open
= op
->open
;
3872 driver
->close
= op
->close
;
3873 driver
->write
= op
->write
;
3874 driver
->put_char
= op
->put_char
;
3875 driver
->flush_chars
= op
->flush_chars
;
3876 driver
->write_room
= op
->write_room
;
3877 driver
->chars_in_buffer
= op
->chars_in_buffer
;
3878 driver
->ioctl
= op
->ioctl
;
3879 driver
->compat_ioctl
= op
->compat_ioctl
;
3880 driver
->set_termios
= op
->set_termios
;
3881 driver
->throttle
= op
->throttle
;
3882 driver
->unthrottle
= op
->unthrottle
;
3883 driver
->stop
= op
->stop
;
3884 driver
->start
= op
->start
;
3885 driver
->hangup
= op
->hangup
;
3886 driver
->break_ctl
= op
->break_ctl
;
3887 driver
->flush_buffer
= op
->flush_buffer
;
3888 driver
->set_ldisc
= op
->set_ldisc
;
3889 driver
->wait_until_sent
= op
->wait_until_sent
;
3890 driver
->send_xchar
= op
->send_xchar
;
3891 driver
->read_proc
= op
->read_proc
;
3892 driver
->write_proc
= op
->write_proc
;
3893 driver
->tiocmget
= op
->tiocmget
;
3894 driver
->tiocmset
= op
->tiocmset
;
3895 #ifdef CONFIG_CONSOLE_POLL
3896 driver
->poll_init
= op
->poll_init
;
3897 driver
->poll_get_char
= op
->poll_get_char
;
3898 driver
->poll_put_char
= op
->poll_put_char
;
3903 EXPORT_SYMBOL(alloc_tty_driver
);
3904 EXPORT_SYMBOL(put_tty_driver
);
3905 EXPORT_SYMBOL(tty_set_operations
);
3908 * Called by a tty driver to register itself.
3910 int tty_register_driver(struct tty_driver
*driver
)
3917 if (driver
->flags
& TTY_DRIVER_INSTALLED
)
3920 if (!(driver
->flags
& TTY_DRIVER_DEVPTS_MEM
) && driver
->num
) {
3921 p
= kzalloc(driver
->num
* 3 * sizeof(void *), GFP_KERNEL
);
3926 if (!driver
->major
) {
3927 error
= alloc_chrdev_region(&dev
, driver
->minor_start
,
3928 driver
->num
, driver
->name
);
3930 driver
->major
= MAJOR(dev
);
3931 driver
->minor_start
= MINOR(dev
);
3934 dev
= MKDEV(driver
->major
, driver
->minor_start
);
3935 error
= register_chrdev_region(dev
, driver
->num
, driver
->name
);
3943 driver
->ttys
= (struct tty_struct
**)p
;
3944 driver
->termios
= (struct ktermios
**)(p
+ driver
->num
);
3945 driver
->termios_locked
= (struct ktermios
**)
3946 (p
+ driver
->num
* 2);
3948 driver
->ttys
= NULL
;
3949 driver
->termios
= NULL
;
3950 driver
->termios_locked
= NULL
;
3953 cdev_init(&driver
->cdev
, &tty_fops
);
3954 driver
->cdev
.owner
= driver
->owner
;
3955 error
= cdev_add(&driver
->cdev
, dev
, driver
->num
);
3957 unregister_chrdev_region(dev
, driver
->num
);
3958 driver
->ttys
= NULL
;
3959 driver
->termios
= driver
->termios_locked
= NULL
;
3964 if (!driver
->put_char
)
3965 driver
->put_char
= tty_default_put_char
;
3967 mutex_lock(&tty_mutex
);
3968 list_add(&driver
->tty_drivers
, &tty_drivers
);
3969 mutex_unlock(&tty_mutex
);
3971 if (!(driver
->flags
& TTY_DRIVER_DYNAMIC_DEV
)) {
3972 for (i
= 0; i
< driver
->num
; i
++)
3973 tty_register_device(driver
, i
, NULL
);
3975 proc_tty_register_driver(driver
);
3979 EXPORT_SYMBOL(tty_register_driver
);
3982 * Called by a tty driver to unregister itself.
3984 int tty_unregister_driver(struct tty_driver
*driver
)
3987 struct ktermios
*tp
;
3990 if (driver
->refcount
)
3993 unregister_chrdev_region(MKDEV(driver
->major
, driver
->minor_start
),
3995 mutex_lock(&tty_mutex
);
3996 list_del(&driver
->tty_drivers
);
3997 mutex_unlock(&tty_mutex
);
4000 * Free the termios and termios_locked structures because
4001 * we don't want to get memory leaks when modular tty
4002 * drivers are removed from the kernel.
4004 for (i
= 0; i
< driver
->num
; i
++) {
4005 tp
= driver
->termios
[i
];
4007 driver
->termios
[i
] = NULL
;
4010 tp
= driver
->termios_locked
[i
];
4012 driver
->termios_locked
[i
] = NULL
;
4015 if (!(driver
->flags
& TTY_DRIVER_DYNAMIC_DEV
))
4016 tty_unregister_device(driver
, i
);
4019 proc_tty_unregister_driver(driver
);
4020 driver
->ttys
= NULL
;
4021 driver
->termios
= driver
->termios_locked
= NULL
;
4023 cdev_del(&driver
->cdev
);
4026 EXPORT_SYMBOL(tty_unregister_driver
);
4028 dev_t
tty_devnum(struct tty_struct
*tty
)
4030 return MKDEV(tty
->driver
->major
, tty
->driver
->minor_start
) + tty
->index
;
4032 EXPORT_SYMBOL(tty_devnum
);
4034 void proc_clear_tty(struct task_struct
*p
)
4036 spin_lock_irq(&p
->sighand
->siglock
);
4037 p
->signal
->tty
= NULL
;
4038 spin_unlock_irq(&p
->sighand
->siglock
);
4040 EXPORT_SYMBOL(proc_clear_tty
);
4042 static void __proc_set_tty(struct task_struct
*tsk
, struct tty_struct
*tty
)
4045 /* We should not have a session or pgrp to here but.... */
4046 put_pid(tty
->session
);
4048 tty
->session
= get_pid(task_session(tsk
));
4049 tty
->pgrp
= get_pid(task_pgrp(tsk
));
4051 put_pid(tsk
->signal
->tty_old_pgrp
);
4052 tsk
->signal
->tty
= tty
;
4053 tsk
->signal
->tty_old_pgrp
= NULL
;
4056 static void proc_set_tty(struct task_struct
*tsk
, struct tty_struct
*tty
)
4058 spin_lock_irq(&tsk
->sighand
->siglock
);
4059 __proc_set_tty(tsk
, tty
);
4060 spin_unlock_irq(&tsk
->sighand
->siglock
);
4063 struct tty_struct
*get_current_tty(void)
4065 struct tty_struct
*tty
;
4066 WARN_ON_ONCE(!mutex_is_locked(&tty_mutex
));
4067 tty
= current
->signal
->tty
;
4069 * session->tty can be changed/cleared from under us, make sure we
4070 * issue the load. The obtained pointer, when not NULL, is valid as
4071 * long as we hold tty_mutex.
4076 EXPORT_SYMBOL_GPL(get_current_tty
);
4079 * Initialize the console device. This is called *early*, so
4080 * we can't necessarily depend on lots of kernel help here.
4081 * Just do some early initializations, and do the complex setup
4084 void __init
console_init(void)
4088 /* Setup the default TTY line discipline. */
4089 (void) tty_register_ldisc(N_TTY
, &tty_ldisc_N_TTY
);
4092 * set up the console device so that later boot sequences can
4093 * inform about problems etc..
4095 call
= __con_initcall_start
;
4096 while (call
< __con_initcall_end
) {
4102 static int __init
tty_class_init(void)
4104 tty_class
= class_create(THIS_MODULE
, "tty");
4105 if (IS_ERR(tty_class
))
4106 return PTR_ERR(tty_class
);
4110 postcore_initcall(tty_class_init
);
4112 /* 3/2004 jmc: why do these devices exist? */
4114 static struct cdev tty_cdev
, console_cdev
;
4115 #ifdef CONFIG_UNIX98_PTYS
4116 static struct cdev ptmx_cdev
;
4119 static struct cdev vc0_cdev
;
4123 * Ok, now we can initialize the rest of the tty devices and can count
4124 * on memory allocations, interrupts etc..
4126 static int __init
tty_init(void)
4128 cdev_init(&tty_cdev
, &tty_fops
);
4129 if (cdev_add(&tty_cdev
, MKDEV(TTYAUX_MAJOR
, 0), 1) ||
4130 register_chrdev_region(MKDEV(TTYAUX_MAJOR
, 0), 1, "/dev/tty") < 0)
4131 panic("Couldn't register /dev/tty driver\n");
4132 device_create(tty_class
, NULL
, MKDEV(TTYAUX_MAJOR
, 0), "tty");
4134 cdev_init(&console_cdev
, &console_fops
);
4135 if (cdev_add(&console_cdev
, MKDEV(TTYAUX_MAJOR
, 1), 1) ||
4136 register_chrdev_region(MKDEV(TTYAUX_MAJOR
, 1), 1, "/dev/console") < 0)
4137 panic("Couldn't register /dev/console driver\n");
4138 device_create(tty_class
, NULL
, MKDEV(TTYAUX_MAJOR
, 1), "console");
4140 #ifdef CONFIG_UNIX98_PTYS
4141 cdev_init(&ptmx_cdev
, &ptmx_fops
);
4142 if (cdev_add(&ptmx_cdev
, MKDEV(TTYAUX_MAJOR
, 2), 1) ||
4143 register_chrdev_region(MKDEV(TTYAUX_MAJOR
, 2), 1, "/dev/ptmx") < 0)
4144 panic("Couldn't register /dev/ptmx driver\n");
4145 device_create(tty_class
, NULL
, MKDEV(TTYAUX_MAJOR
, 2), "ptmx");
4149 cdev_init(&vc0_cdev
, &console_fops
);
4150 if (cdev_add(&vc0_cdev
, MKDEV(TTY_MAJOR
, 0), 1) ||
4151 register_chrdev_region(MKDEV(TTY_MAJOR
, 0), 1, "/dev/vc/0") < 0)
4152 panic("Couldn't register /dev/tty0 driver\n");
4153 device_create(tty_class
, NULL
, MKDEV(TTY_MAJOR
, 0), "tty0");
4159 module_init(tty_init
);