/* * linux/drivers/char/tty_io.c * * Copyright (C) 1991, 1992 Linus Torvalds */ /* * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles * or rs-channels. It also implements echoing, cooked mode etc. * * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0. * * Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the * tty_struct and tty_queue structures. Previously there was an array * of 256 tty_struct's which was statically allocated, and the * tty_queue structures were allocated at boot time. Both are now * dynamically allocated only when the tty is open. * * Also restructured routines so that there is more of a separation * between the high-level tty routines (tty_io.c and tty_ioctl.c) and * the low-level tty routines (serial.c, pty.c, console.c). This * makes for cleaner and more compact code. -TYT, 9/17/92 * * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines * which can be dynamically activated and de-activated by the line * discipline handling modules (like SLIP). * * NOTE: pay no attention to the line discipline code (yet); its * interface is still subject to change in this version... * -- TYT, 1/31/92 * * Added functionality to the OPOST tty handling. No delays, but all * other bits should be there. * -- Nick Holloway , 27th May 1993. * * Rewrote canonical mode and added more termios flags. * -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94 * * Reorganized FASYNC support so mouse code can share it. * -- ctm@ardi.com, 9Sep95 * * New TIOCLINUX variants added. * -- mj@k332.feld.cvut.cz, 19-Nov-95 * * Restrict vt switching via ioctl() * -- grif@cs.ucr.edu, 5-Dec-95 * * Move console and virtual terminal code to more appropriate files, * implement CONFIG_VT and generalize console device interface. * -- Marko Kohtala , March 97 * * Rewrote init_dev and release_dev to eliminate races. * -- Bill Hawes , June 97 * * Added devfs support. * -- C. Scott Ananian , 13-Jan-1998 * * Added support for a Unix98-style ptmx device. * -- C. Scott Ananian , 14-Jan-1998 * * Reduced memory usage for older ARM systems * -- Russell King * * Move do_SAK() into process context. Less stack use in devfs functions. * alloc_tty_struct() always uses kmalloc() -- Andrew Morton 17Mar01 */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #undef TTY_DEBUG_HANGUP #define TTY_PARANOIA_CHECK 1 #define CHECK_TTY_COUNT 1 struct ktermios tty_std_termios = { /* for the benefit of tty drivers */ .c_iflag = ICRNL | IXON, .c_oflag = OPOST | ONLCR, .c_cflag = B38400 | CS8 | CREAD | HUPCL, .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOKE | IEXTEN, .c_cc = INIT_C_CC, .c_ispeed = 38400, .c_ospeed = 38400 }; EXPORT_SYMBOL(tty_std_termios); /* This list gets poked at by procfs and various bits of boot up code. This could do with some rationalisation such as pulling the tty proc function into this file */ LIST_HEAD(tty_drivers); /* linked list of tty drivers */ /* Mutex to protect creating and releasing a tty. This is shared with vt.c for deeply disgusting hack reasons */ DEFINE_MUTEX(tty_mutex); EXPORT_SYMBOL(tty_mutex); #ifdef CONFIG_UNIX98_PTYS extern struct tty_driver *ptm_driver; /* Unix98 pty masters; for /dev/ptmx */ extern int pty_limit; /* Config limit on Unix98 ptys */ static DEFINE_IDR(allocated_ptys); static DECLARE_MUTEX(allocated_ptys_lock); static int ptmx_open(struct inode *, struct file *); #endif extern void disable_early_printk(void); static void initialize_tty_struct(struct tty_struct *tty); static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *); static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *); ssize_t redirected_tty_write(struct file *, const char __user *, size_t, loff_t *); static unsigned int tty_poll(struct file *, poll_table *); static int tty_open(struct inode *, struct file *); static int tty_release(struct inode *, struct file *); int tty_ioctl(struct inode * inode, struct file * file, unsigned int cmd, unsigned long arg); static int tty_fasync(int fd, struct file * filp, int on); static void release_mem(struct tty_struct *tty, int idx); /** * alloc_tty_struct - allocate a tty object * * Return a new empty tty structure. The data fields have not * been initialized in any way but has been zeroed * * Locking: none */ static struct tty_struct *alloc_tty_struct(void) { return kzalloc(sizeof(struct tty_struct), GFP_KERNEL); } static void tty_buffer_free_all(struct tty_struct *); /** * free_tty_struct - free a disused tty * @tty: tty struct to free * * Free the write buffers, tty queue and tty memory itself. * * Locking: none. Must be called after tty is definitely unused */ static inline void free_tty_struct(struct tty_struct *tty) { kfree(tty->write_buf); tty_buffer_free_all(tty); kfree(tty); } #define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base) /** * tty_name - return tty naming * @tty: tty structure * @buf: buffer for output * * Convert a tty structure into a name. The name reflects the kernel * naming policy and if udev is in use may not reflect user space * * Locking: none */ char *tty_name(struct tty_struct *tty, char *buf) { if (!tty) /* Hmm. NULL pointer. That's fun. */ strcpy(buf, "NULL tty"); else strcpy(buf, tty->name); return buf; } EXPORT_SYMBOL(tty_name); int tty_paranoia_check(struct tty_struct *tty, struct inode *inode, const char *routine) { #ifdef TTY_PARANOIA_CHECK if (!tty) { printk(KERN_WARNING "null TTY for (%d:%d) in %s\n", imajor(inode), iminor(inode), routine); return 1; } if (tty->magic != TTY_MAGIC) { printk(KERN_WARNING "bad magic number for tty struct (%d:%d) in %s\n", imajor(inode), iminor(inode), routine); return 1; } #endif return 0; } static int check_tty_count(struct tty_struct *tty, const char *routine) { #ifdef CHECK_TTY_COUNT struct list_head *p; int count = 0; file_list_lock(); list_for_each(p, &tty->tty_files) { count++; } file_list_unlock(); if (tty->driver->type == TTY_DRIVER_TYPE_PTY && tty->driver->subtype == PTY_TYPE_SLAVE && tty->link && tty->link->count) count++; if (tty->count != count) { printk(KERN_WARNING "Warning: dev (%s) tty->count(%d) " "!= #fd's(%d) in %s\n", tty->name, tty->count, count, routine); return count; } #endif return 0; } /* * Tty buffer allocation management */ /** * tty_buffer_free_all - free buffers used by a tty * @tty: tty to free from * * Remove all the buffers pending on a tty whether queued with data * or in the free ring. Must be called when the tty is no longer in use * * Locking: none */ static void tty_buffer_free_all(struct tty_struct *tty) { struct tty_buffer *thead; while((thead = tty->buf.head) != NULL) { tty->buf.head = thead->next; kfree(thead); } while((thead = tty->buf.free) != NULL) { tty->buf.free = thead->next; kfree(thead); } tty->buf.tail = NULL; tty->buf.memory_used = 0; } /** * tty_buffer_init - prepare a tty buffer structure * @tty: tty to initialise * * Set up the initial state of the buffer management for a tty device. * Must be called before the other tty buffer functions are used. * * Locking: none */ static void tty_buffer_init(struct tty_struct *tty) { spin_lock_init(&tty->buf.lock); tty->buf.head = NULL; tty->buf.tail = NULL; tty->buf.free = NULL; tty->buf.memory_used = 0; } /** * tty_buffer_alloc - allocate a tty buffer * @tty: tty device * @size: desired size (characters) * * Allocate a new tty buffer to hold the desired number of characters. * Return NULL if out of memory or the allocation would exceed the * per device queue * * Locking: Caller must hold tty->buf.lock */ static struct tty_buffer *tty_buffer_alloc(struct tty_struct *tty, size_t size) { struct tty_buffer *p; if (tty->buf.memory_used + size > 65536) return NULL; p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC); if(p == NULL) return NULL; p->used = 0; p->size = size; p->next = NULL; p->commit = 0; p->read = 0; p->char_buf_ptr = (char *)(p->data); p->flag_buf_ptr = (unsigned char *)p->char_buf_ptr + size; tty->buf.memory_used += size; return p; } /** * tty_buffer_free - free a tty buffer * @tty: tty owning the buffer * @b: the buffer to free * * Free a tty buffer, or add it to the free list according to our * internal strategy * * Locking: Caller must hold tty->buf.lock */ static void tty_buffer_free(struct tty_struct *tty, struct tty_buffer *b) { /* Dumb strategy for now - should keep some stats */ tty->buf.memory_used -= b->size; WARN_ON(tty->buf.memory_used < 0); if(b->size >= 512) kfree(b); else { b->next = tty->buf.free; tty->buf.free = b; } } /** * tty_buffer_find - find a free tty buffer * @tty: tty owning the buffer * @size: characters wanted * * Locate an existing suitable tty buffer or if we are lacking one then * allocate a new one. We round our buffers off in 256 character chunks * to get better allocation behaviour. * * Locking: Caller must hold tty->buf.lock */ static struct tty_buffer *tty_buffer_find(struct tty_struct *tty, size_t size) { struct tty_buffer **tbh = &tty->buf.free; while((*tbh) != NULL) { struct tty_buffer *t = *tbh; if(t->size >= size) { *tbh = t->next; t->next = NULL; t->used = 0; t->commit = 0; t->read = 0; tty->buf.memory_used += t->size; return t; } tbh = &((*tbh)->next); } /* Round the buffer size out */ size = (size + 0xFF) & ~ 0xFF; return tty_buffer_alloc(tty, size); /* Should possibly check if this fails for the largest buffer we have queued and recycle that ? */ } /** * tty_buffer_request_room - grow tty buffer if needed * @tty: tty structure * @size: size desired * * Make at least size bytes of linear space available for the tty * buffer. If we fail return the size we managed to find. * * Locking: Takes tty->buf.lock */ int tty_buffer_request_room(struct tty_struct *tty, size_t size) { struct tty_buffer *b, *n; int left; unsigned long flags; spin_lock_irqsave(&tty->buf.lock, flags); /* OPTIMISATION: We could keep a per tty "zero" sized buffer to remove this conditional if its worth it. This would be invisible to the callers */ if ((b = tty->buf.tail) != NULL) left = b->size - b->used; else left = 0; if (left < size) { /* This is the slow path - looking for new buffers to use */ if ((n = tty_buffer_find(tty, size)) != NULL) { if (b != NULL) { b->next = n; b->commit = b->used; } else tty->buf.head = n; tty->buf.tail = n; } else size = left; } spin_unlock_irqrestore(&tty->buf.lock, flags); return size; } EXPORT_SYMBOL_GPL(tty_buffer_request_room); /** * tty_insert_flip_string - Add characters to the tty buffer * @tty: tty structure * @chars: characters * @size: size * * Queue a series of bytes to the tty buffering. All the characters * passed are marked as without error. Returns the number added. * * Locking: Called functions may take tty->buf.lock */ int tty_insert_flip_string(struct tty_struct *tty, const unsigned char *chars, size_t size) { int copied = 0; do { int space = tty_buffer_request_room(tty, size - copied); struct tty_buffer *tb = tty->buf.tail; /* If there is no space then tb may be NULL */ if(unlikely(space == 0)) break; memcpy(tb->char_buf_ptr + tb->used, chars, space); memset(tb->flag_buf_ptr + tb->used, TTY_NORMAL, space); tb->used += space; copied += space; chars += space; /* There is a small chance that we need to split the data over several buffers. If this is the case we must loop */ } while (unlikely(size > copied)); return copied; } EXPORT_SYMBOL(tty_insert_flip_string); /** * tty_insert_flip_string_flags - Add characters to the tty buffer * @tty: tty structure * @chars: characters * @flags: flag bytes * @size: size * * Queue a series of bytes to the tty buffering. For each character * the flags array indicates the status of the character. Returns the * number added. * * Locking: Called functions may take tty->buf.lock */ int tty_insert_flip_string_flags(struct tty_struct *tty, const unsigned char *chars, const char *flags, size_t size) { int copied = 0; do { int space = tty_buffer_request_room(tty, size - copied); struct tty_buffer *tb = tty->buf.tail; /* If there is no space then tb may be NULL */ if(unlikely(space == 0)) break; memcpy(tb->char_buf_ptr + tb->used, chars, space); memcpy(tb->flag_buf_ptr + tb->used, flags, space); tb->used += space; copied += space; chars += space; flags += space; /* There is a small chance that we need to split the data over several buffers. If this is the case we must loop */ } while (unlikely(size > copied)); return copied; } EXPORT_SYMBOL(tty_insert_flip_string_flags); /** * tty_schedule_flip - push characters to ldisc * @tty: tty to push from * * Takes any pending buffers and transfers their ownership to the * ldisc side of the queue. It then schedules those characters for * processing by the line discipline. * * Locking: Takes tty->buf.lock */ void tty_schedule_flip(struct tty_struct *tty) { unsigned long flags; spin_lock_irqsave(&tty->buf.lock, flags); if (tty->buf.tail != NULL) tty->buf.tail->commit = tty->buf.tail->used; spin_unlock_irqrestore(&tty->buf.lock, flags); schedule_delayed_work(&tty->buf.work, 1); } EXPORT_SYMBOL(tty_schedule_flip); /** * tty_prepare_flip_string - make room for characters * @tty: tty * @chars: return pointer for character write area * @size: desired size * * Prepare a block of space in the buffer for data. Returns the length * available and buffer pointer to the space which is now allocated and * accounted for as ready for normal characters. This is used for drivers * that need their own block copy routines into the buffer. There is no * guarantee the buffer is a DMA target! * * Locking: May call functions taking tty->buf.lock */ int tty_prepare_flip_string(struct tty_struct *tty, unsigned char **chars, size_t size) { int space = tty_buffer_request_room(tty, size); if (likely(space)) { struct tty_buffer *tb = tty->buf.tail; *chars = tb->char_buf_ptr + tb->used; memset(tb->flag_buf_ptr + tb->used, TTY_NORMAL, space); tb->used += space; } return space; } EXPORT_SYMBOL_GPL(tty_prepare_flip_string); /** * tty_prepare_flip_string_flags - make room for characters * @tty: tty * @chars: return pointer for character write area * @flags: return pointer for status flag write area * @size: desired size * * Prepare a block of space in the buffer for data. Returns the length * available and buffer pointer to the space which is now allocated and * accounted for as ready for characters. This is used for drivers * that need their own block copy routines into the buffer. There is no * guarantee the buffer is a DMA target! * * Locking: May call functions taking tty->buf.lock */ int tty_prepare_flip_string_flags(struct tty_struct *tty, unsigned char **chars, char **flags, size_t size) { int space = tty_buffer_request_room(tty, size); if (likely(space)) { struct tty_buffer *tb = tty->buf.tail; *chars = tb->char_buf_ptr + tb->used; *flags = tb->flag_buf_ptr + tb->used; tb->used += space; } return space; } EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags); /** * tty_set_termios_ldisc - set ldisc field * @tty: tty structure * @num: line discipline number * * This is probably overkill for real world processors but * they are not on hot paths so a little discipline won't do * any harm. * * Locking: takes termios_mutex */ static void tty_set_termios_ldisc(struct tty_struct *tty, int num) { mutex_lock(&tty->termios_mutex); tty->termios->c_line = num; mutex_unlock(&tty->termios_mutex); } /* * This guards the refcounted line discipline lists. The lock * must be taken with irqs off because there are hangup path * callers who will do ldisc lookups and cannot sleep. */ static DEFINE_SPINLOCK(tty_ldisc_lock); static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_wait); static struct tty_ldisc tty_ldiscs[NR_LDISCS]; /* line disc dispatch table */ /** * tty_register_ldisc - install a line discipline * @disc: ldisc number * @new_ldisc: pointer to the ldisc object * * Installs a new line discipline into the kernel. The discipline * is set up as unreferenced and then made available to the kernel * from this point onwards. * * Locking: * takes tty_ldisc_lock to guard against ldisc races */ int tty_register_ldisc(int disc, struct tty_ldisc *new_ldisc) { unsigned long flags; int ret = 0; if (disc < N_TTY || disc >= NR_LDISCS) return -EINVAL; spin_lock_irqsave(&tty_ldisc_lock, flags); tty_ldiscs[disc] = *new_ldisc; tty_ldiscs[disc].num = disc; tty_ldiscs[disc].flags |= LDISC_FLAG_DEFINED; tty_ldiscs[disc].refcount = 0; spin_unlock_irqrestore(&tty_ldisc_lock, flags); return ret; } EXPORT_SYMBOL(tty_register_ldisc); /** * tty_unregister_ldisc - unload a line discipline * @disc: ldisc number * @new_ldisc: pointer to the ldisc object * * Remove a line discipline from the kernel providing it is not * currently in use. * * Locking: * takes tty_ldisc_lock to guard against ldisc races */ int tty_unregister_ldisc(int disc) { unsigned long flags; int ret = 0; if (disc < N_TTY || disc >= NR_LDISCS) return -EINVAL; spin_lock_irqsave(&tty_ldisc_lock, flags); if (tty_ldiscs[disc].refcount) ret = -EBUSY; else tty_ldiscs[disc].flags &= ~LDISC_FLAG_DEFINED; spin_unlock_irqrestore(&tty_ldisc_lock, flags); return ret; } EXPORT_SYMBOL(tty_unregister_ldisc); /** * tty_ldisc_get - take a reference to an ldisc * @disc: ldisc number * * Takes a reference to a line discipline. Deals with refcounts and * module locking counts. Returns NULL if the discipline is not available. * Returns a pointer to the discipline and bumps the ref count if it is * available * * Locking: * takes tty_ldisc_lock to guard against ldisc races */ struct tty_ldisc *tty_ldisc_get(int disc) { unsigned long flags; struct tty_ldisc *ld; if (disc < N_TTY || disc >= NR_LDISCS) return NULL; spin_lock_irqsave(&tty_ldisc_lock, flags); ld = &tty_ldiscs[disc]; /* Check the entry is defined */ if(ld->flags & LDISC_FLAG_DEFINED) { /* If the module is being unloaded we can't use it */ if (!try_module_get(ld->owner)) ld = NULL; else /* lock it */ ld->refcount++; } else ld = NULL; spin_unlock_irqrestore(&tty_ldisc_lock, flags); return ld; } EXPORT_SYMBOL_GPL(tty_ldisc_get); /** * tty_ldisc_put - drop ldisc reference * @disc: ldisc number * * Drop a reference to a line discipline. Manage refcounts and * module usage counts * * Locking: * takes tty_ldisc_lock to guard against ldisc races */ void tty_ldisc_put(int disc) { struct tty_ldisc *ld; unsigned long flags; BUG_ON(disc < N_TTY || disc >= NR_LDISCS); spin_lock_irqsave(&tty_ldisc_lock, flags); ld = &tty_ldiscs[disc]; BUG_ON(ld->refcount == 0); ld->refcount--; module_put(ld->owner); spin_unlock_irqrestore(&tty_ldisc_lock, flags); } EXPORT_SYMBOL_GPL(tty_ldisc_put); /** * tty_ldisc_assign - set ldisc on a tty * @tty: tty to assign * @ld: line discipline * * Install an instance of a line discipline into a tty structure. The * ldisc must have a reference count above zero to ensure it remains/ * The tty instance refcount starts at zero. * * Locking: * Caller must hold references */ static void tty_ldisc_assign(struct tty_struct *tty, struct tty_ldisc *ld) { tty->ldisc = *ld; tty->ldisc.refcount = 0; } /** * tty_ldisc_try - internal helper * @tty: the tty * * Make a single attempt to grab and bump the refcount on * the tty ldisc. Return 0 on failure or 1 on success. This is * used to implement both the waiting and non waiting versions * of tty_ldisc_ref * * Locking: takes tty_ldisc_lock */ static int tty_ldisc_try(struct tty_struct *tty) { unsigned long flags; struct tty_ldisc *ld; int ret = 0; spin_lock_irqsave(&tty_ldisc_lock, flags); ld = &tty->ldisc; if(test_bit(TTY_LDISC, &tty->flags)) { ld->refcount++; ret = 1; } spin_unlock_irqrestore(&tty_ldisc_lock, flags); return ret; } /** * tty_ldisc_ref_wait - wait for the tty ldisc * @tty: tty device * * Dereference the line discipline for the terminal and take a * reference to it. If the line discipline is in flux then * wait patiently until it changes. * * Note: Must not be called from an IRQ/timer context. The caller * must also be careful not to hold other locks that will deadlock * against a discipline change, such as an existing ldisc reference * (which we check for) * * Locking: call functions take tty_ldisc_lock */ struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty) { /* wait_event is a macro */ wait_event(tty_ldisc_wait, tty_ldisc_try(tty)); if(tty->ldisc.refcount == 0) printk(KERN_ERR "tty_ldisc_ref_wait\n"); return &tty->ldisc; } EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait); /** * tty_ldisc_ref - get the tty ldisc * @tty: tty device * * Dereference the line discipline for the terminal and take a * reference to it. If the line discipline is in flux then * return NULL. Can be called from IRQ and timer functions. * * Locking: called functions take tty_ldisc_lock */ struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty) { if(tty_ldisc_try(tty)) return &tty->ldisc; return NULL; } EXPORT_SYMBOL_GPL(tty_ldisc_ref); /** * tty_ldisc_deref - free a tty ldisc reference * @ld: reference to free up * * Undoes the effect of tty_ldisc_ref or tty_ldisc_ref_wait. May * be called in IRQ context. * * Locking: takes tty_ldisc_lock */ void tty_ldisc_deref(struct tty_ldisc *ld) { unsigned long flags; BUG_ON(ld == NULL); spin_lock_irqsave(&tty_ldisc_lock, flags); if(ld->refcount == 0) printk(KERN_ERR "tty_ldisc_deref: no references.\n"); else ld->refcount--; if(ld->refcount == 0) wake_up(&tty_ldisc_wait); spin_unlock_irqrestore(&tty_ldisc_lock, flags); } EXPORT_SYMBOL_GPL(tty_ldisc_deref); /** * tty_ldisc_enable - allow ldisc use * @tty: terminal to activate ldisc on * * Set the TTY_LDISC flag when the line discipline can be called * again. Do neccessary wakeups for existing sleepers. * * Note: nobody should set this bit except via this function. Clearing * directly is allowed. */ static void tty_ldisc_enable(struct tty_struct *tty) { set_bit(TTY_LDISC, &tty->flags); wake_up(&tty_ldisc_wait); } /** * tty_set_ldisc - set line discipline * @tty: the terminal to set * @ldisc: the line discipline * * Set the discipline of a tty line. Must be called from a process * context. * * Locking: takes tty_ldisc_lock. * called functions take termios_mutex */ static int tty_set_ldisc(struct tty_struct *tty, int ldisc) { int retval = 0; struct tty_ldisc o_ldisc; char buf[64]; int work; unsigned long flags; struct tty_ldisc *ld; struct tty_struct *o_tty; if ((ldisc < N_TTY) || (ldisc >= NR_LDISCS)) return -EINVAL; restart: ld = tty_ldisc_get(ldisc); /* Eduardo Blanco */ /* Cyrus Durgin */ if (ld == NULL) { request_module("tty-ldisc-%d", ldisc); ld = tty_ldisc_get(ldisc); } if (ld == NULL) return -EINVAL; /* * No more input please, we are switching. The new ldisc * will update this value in the ldisc open function */ tty->receive_room = 0; /* * Problem: What do we do if this blocks ? */ tty_wait_until_sent(tty, 0); if (tty->ldisc.num == ldisc) { tty_ldisc_put(ldisc); return 0; } o_ldisc = tty->ldisc; o_tty = tty->link; /* * Make sure we don't change while someone holds a * reference to the line discipline. The TTY_LDISC bit * prevents anyone taking a reference once it is clear. * We need the lock to avoid racing reference takers. */ spin_lock_irqsave(&tty_ldisc_lock, flags); if (tty->ldisc.refcount || (o_tty && o_tty->ldisc.refcount)) { if(tty->ldisc.refcount) { /* Free the new ldisc we grabbed. Must drop the lock first. */ spin_unlock_irqrestore(&tty_ldisc_lock, flags); tty_ldisc_put(ldisc); /* * There are several reasons we may be busy, including * random momentary I/O traffic. We must therefore * retry. We could distinguish between blocking ops * and retries if we made tty_ldisc_wait() smarter. That * is up for discussion. */ if (wait_event_interruptible(tty_ldisc_wait, tty->ldisc.refcount == 0) < 0) return -ERESTARTSYS; goto restart; } if(o_tty && o_tty->ldisc.refcount) { spin_unlock_irqrestore(&tty_ldisc_lock, flags); tty_ldisc_put(ldisc); if (wait_event_interruptible(tty_ldisc_wait, o_tty->ldisc.refcount == 0) < 0) return -ERESTARTSYS; goto restart; } } /* if the TTY_LDISC bit is set, then we are racing against another ldisc change */ if (!test_bit(TTY_LDISC, &tty->flags)) { spin_unlock_irqrestore(&tty_ldisc_lock, flags); tty_ldisc_put(ldisc); ld = tty_ldisc_ref_wait(tty); tty_ldisc_deref(ld); goto restart; } clear_bit(TTY_LDISC, &tty->flags); if (o_tty) clear_bit(TTY_LDISC, &o_tty->flags); spin_unlock_irqrestore(&tty_ldisc_lock, flags); /* * From this point on we know nobody has an ldisc * usage reference, nor can they obtain one until * we say so later on. */ work = cancel_delayed_work(&tty->buf.work); /* * Wait for ->hangup_work and ->buf.work handlers to terminate */ flush_scheduled_work(); /* Shutdown the current discipline. */ if (tty->ldisc.close) (tty->ldisc.close)(tty); /* Now set up the new line discipline. */ tty_ldisc_assign(tty, ld); tty_set_termios_ldisc(tty, ldisc); if (tty->ldisc.open) retval = (tty->ldisc.open)(tty); if (retval < 0) { tty_ldisc_put(ldisc); /* There is an outstanding reference here so this is safe */ tty_ldisc_assign(tty, tty_ldisc_get(o_ldisc.num)); tty_set_termios_ldisc(tty, tty->ldisc.num); if (tty->ldisc.open && (tty->ldisc.open(tty) < 0)) { tty_ldisc_put(o_ldisc.num); /* This driver is always present */ tty_ldisc_assign(tty, tty_ldisc_get(N_TTY)); tty_set_termios_ldisc(tty, N_TTY); if (tty->ldisc.open) { int r = tty->ldisc.open(tty); if (r < 0) panic("Couldn't open N_TTY ldisc for " "%s --- error %d.", tty_name(tty, buf), r); } } } /* At this point we hold a reference to the new ldisc and a a reference to the old ldisc. If we ended up flipping back to the existing ldisc we have two references to it */ if (tty->ldisc.num != o_ldisc.num && tty->driver->set_ldisc) tty->driver->set_ldisc(tty); tty_ldisc_put(o_ldisc.num); /* * Allow ldisc referencing to occur as soon as the driver * ldisc callback completes. */ tty_ldisc_enable(tty); if (o_tty) tty_ldisc_enable(o_tty); /* Restart it in case no characters kick it off. Safe if already running */ if (work) schedule_delayed_work(&tty->buf.work, 1); return retval; } /** * get_tty_driver - find device of a tty * @dev_t: device identifier * @index: returns the index of the tty * * This routine returns a tty driver structure, given a device number * and also passes back the index number. * * Locking: caller must hold tty_mutex */ static struct tty_driver *get_tty_driver(dev_t device, int *index) { struct tty_driver *p; list_for_each_entry(p, &tty_drivers, tty_drivers) { dev_t base = MKDEV(p->major, p->minor_start); if (device < base || device >= base + p->num) continue; *index = device - base; return p; } return NULL; } /** * tty_check_change - check for POSIX terminal changes * @tty: tty to check * * If we try to write to, or set the state of, a terminal and we're * not in the foreground, send a SIGTTOU. If the signal is blocked or * ignored, go ahead and perform the operation. (POSIX 7.2) * * Locking: none */ int tty_check_change(struct tty_struct * tty) { if (current->signal->tty != tty) return 0; if (tty->pgrp <= 0) { printk(KERN_WARNING "tty_check_change: tty->pgrp <= 0!\n"); return 0; } if (process_group(current) == tty->pgrp) return 0; if (is_ignored(SIGTTOU)) return 0; if (is_orphaned_pgrp(process_group(current))) return -EIO; (void) kill_pg(process_group(current), SIGTTOU, 1); return -ERESTARTSYS; } EXPORT_SYMBOL(tty_check_change); static ssize_t hung_up_tty_read(struct file * file, char __user * buf, size_t count, loff_t *ppos) { return 0; } static ssize_t hung_up_tty_write(struct file * file, const char __user * buf, size_t count, loff_t *ppos) { return -EIO; } /* No kernel lock held - none needed ;) */ static unsigned int hung_up_tty_poll(struct file * filp, poll_table * wait) { return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM; } static int hung_up_tty_ioctl(struct inode * inode, struct file * file, unsigned int cmd, unsigned long arg) { return cmd == TIOCSPGRP ? -ENOTTY : -EIO; } static const struct file_operations tty_fops = { .llseek = no_llseek, .read = tty_read, .write = tty_write, .poll = tty_poll, .ioctl = tty_ioctl, .open = tty_open, .release = tty_release, .fasync = tty_fasync, }; #ifdef CONFIG_UNIX98_PTYS static const struct file_operations ptmx_fops = { .llseek = no_llseek, .read = tty_read, .write = tty_write, .poll = tty_poll, .ioctl = tty_ioctl, .open = ptmx_open, .release = tty_release, .fasync = tty_fasync, }; #endif static const struct file_operations console_fops = { .llseek = no_llseek, .read = tty_read, .write = redirected_tty_write, .poll = tty_poll, .ioctl = tty_ioctl, .open = tty_open, .release = tty_release, .fasync = tty_fasync, }; static const struct file_operations hung_up_tty_fops = { .llseek = no_llseek, .read = hung_up_tty_read, .write = hung_up_tty_write, .poll = hung_up_tty_poll, .ioctl = hung_up_tty_ioctl, .release = tty_release, }; static DEFINE_SPINLOCK(redirect_lock); static struct file *redirect; /** * tty_wakeup - request more data * @tty: terminal * * Internal and external helper for wakeups of tty. This function * informs the line discipline if present that the driver is ready * to receive more output data. */ void tty_wakeup(struct tty_struct *tty) { struct tty_ldisc *ld; if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) { ld = tty_ldisc_ref(tty); if(ld) { if(ld->write_wakeup) ld->write_wakeup(tty); tty_ldisc_deref(ld); } } wake_up_interruptible(&tty->write_wait); } EXPORT_SYMBOL_GPL(tty_wakeup); /** * tty_ldisc_flush - flush line discipline queue * @tty: tty * * Flush the line discipline queue (if any) for this tty. If there * is no line discipline active this is a no-op. */ void tty_ldisc_flush(struct tty_struct *tty) { struct tty_ldisc *ld = tty_ldisc_ref(tty); if(ld) { if(ld->flush_buffer) ld->flush_buffer(tty); tty_ldisc_deref(ld); } } EXPORT_SYMBOL_GPL(tty_ldisc_flush); /** * tty_reset_termios - reset terminal state * @tty: tty to reset * * Restore a terminal to the driver default state */ static void tty_reset_termios(struct tty_struct *tty) { mutex_lock(&tty->termios_mutex); *tty->termios = tty->driver->init_termios; tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios); tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios); mutex_unlock(&tty->termios_mutex); } /** * do_tty_hangup - actual handler for hangup events * @work: tty device * * This can be called by the "eventd" kernel thread. That is process * synchronous but doesn't hold any locks, so we need to make sure we * have the appropriate locks for what we're doing. * * The hangup event clears any pending redirections onto the hung up * device. It ensures future writes will error and it does the needed * line discipline hangup and signal delivery. The tty object itself * remains intact. * * Locking: * BKL * redirect lock for undoing redirection * file list lock for manipulating list of ttys * tty_ldisc_lock from called functions * termios_mutex resetting termios data * tasklist_lock to walk task list for hangup event * ->siglock to protect ->signal/->sighand */ static void do_tty_hangup(struct work_struct *work) { struct tty_struct *tty = container_of(work, struct tty_struct, hangup_work); struct file * cons_filp = NULL; struct file *filp, *f = NULL; struct task_struct *p; struct tty_ldisc *ld; int closecount = 0, n; if (!tty) return; /* inuse_filps is protected by the single kernel lock */ lock_kernel(); spin_lock(&redirect_lock); if (redirect && redirect->private_data == tty) { f = redirect; redirect = NULL; } spin_unlock(&redirect_lock); check_tty_count(tty, "do_tty_hangup"); file_list_lock(); /* This breaks for file handles being sent over AF_UNIX sockets ? */ list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) { if (filp->f_op->write == redirected_tty_write) cons_filp = filp; if (filp->f_op->write != tty_write) continue; closecount++; tty_fasync(-1, filp, 0); /* can't block */ filp->f_op = &hung_up_tty_fops; } file_list_unlock(); /* FIXME! What are the locking issues here? This may me overdoing things.. * this question is especially important now that we've removed the irqlock. */ ld = tty_ldisc_ref(tty); if(ld != NULL) /* We may have no line discipline at this point */ { if (ld->flush_buffer) ld->flush_buffer(tty); if (tty->driver->flush_buffer) tty->driver->flush_buffer(tty); if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) && ld->write_wakeup) ld->write_wakeup(tty); if (ld->hangup) ld->hangup(tty); } /* FIXME: Once we trust the LDISC code better we can wait here for ldisc completion and fix the driver call race */ wake_up_interruptible(&tty->write_wait); wake_up_interruptible(&tty->read_wait); /* * Shutdown the current line discipline, and reset it to * N_TTY. */ if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) tty_reset_termios(tty); /* Defer ldisc switch */ /* tty_deferred_ldisc_switch(N_TTY); This should get done automatically when the port closes and tty_release is called */ read_lock(&tasklist_lock); if (tty->session > 0) { do_each_task_pid(tty->session, PIDTYPE_SID, p) { spin_lock_irq(&p->sighand->siglock); if (p->signal->tty == tty) p->signal->tty = NULL; if (!p->signal->leader) { spin_unlock_irq(&p->sighand->siglock); continue; } __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p); __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p); if (tty->pgrp > 0) p->signal->tty_old_pgrp = tty->pgrp; spin_unlock_irq(&p->sighand->siglock); } while_each_task_pid(tty->session, PIDTYPE_SID, p); } read_unlock(&tasklist_lock); tty->flags = 0; tty->session = 0; tty->pgrp = -1; tty->ctrl_status = 0; /* * If one of the devices matches a console pointer, we * cannot just call hangup() because that will cause * tty->count and state->count to go out of sync. * So we just call close() the right number of times. */ if (cons_filp) { if (tty->driver->close) for (n = 0; n < closecount; n++) tty->driver->close(tty, cons_filp); } else if (tty->driver->hangup) (tty->driver->hangup)(tty); /* We don't want to have driver/ldisc interactions beyond the ones we did here. The driver layer expects no calls after ->hangup() from the ldisc side. However we can't yet guarantee all that */ set_bit(TTY_HUPPED, &tty->flags); if (ld) { tty_ldisc_enable(tty); tty_ldisc_deref(ld); } unlock_kernel(); if (f) fput(f); } /** * tty_hangup - trigger a hangup event * @tty: tty to hangup * * A carrier loss (virtual or otherwise) has occurred on this like * schedule a hangup sequence to run after this event. */ void tty_hangup(struct tty_struct * tty) { #ifdef TTY_DEBUG_HANGUP char buf[64]; printk(KERN_DEBUG "%s hangup...\n", tty_name(tty, buf)); #endif schedule_work(&tty->hangup_work); } EXPORT_SYMBOL(tty_hangup); /** * tty_vhangup - process vhangup * @tty: tty to hangup * * The user has asked via system call for the terminal to be hung up. * We do this synchronously so that when the syscall returns the process * is complete. That guarantee is neccessary for security reasons. */ void tty_vhangup(struct tty_struct * tty) { #ifdef TTY_DEBUG_HANGUP char buf[64]; printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf)); #endif do_tty_hangup(&tty->hangup_work); } EXPORT_SYMBOL(tty_vhangup); /** * tty_hung_up_p - was tty hung up * @filp: file pointer of tty * * Return true if the tty has been subject to a vhangup or a carrier * loss */ int tty_hung_up_p(struct file * filp) { return (filp->f_op == &hung_up_tty_fops); } EXPORT_SYMBOL(tty_hung_up_p); static void session_clear_tty(pid_t session) { struct task_struct *p; do_each_task_pid(session, PIDTYPE_SID, p) { proc_clear_tty(p); } while_each_task_pid(session, PIDTYPE_SID, p); } /** * disassociate_ctty - disconnect controlling tty * @on_exit: true if exiting so need to "hang up" the session * * This function is typically called only by the session leader, when * it wants to disassociate itself from its controlling tty. * * It performs the following functions: * (1) Sends a SIGHUP and SIGCONT to the foreground process group * (2) Clears the tty from being controlling the session * (3) Clears the controlling tty for all processes in the * session group. * * The argument on_exit is set to 1 if called when a process is * exiting; it is 0 if called by the ioctl TIOCNOTTY. * * Locking: * BKL is taken for hysterical raisins * tty_mutex is taken to protect tty * ->siglock is taken to protect ->signal/->sighand * tasklist_lock is taken to walk process list for sessions * ->siglock is taken to protect ->signal/->sighand */ void disassociate_ctty(int on_exit) { struct tty_struct *tty; int tty_pgrp = -1; int session; lock_kernel(); mutex_lock(&tty_mutex); tty = get_current_tty(); if (tty) { tty_pgrp = tty->pgrp; mutex_unlock(&tty_mutex); /* XXX: here we race, there is nothing protecting tty */ if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY) tty_vhangup(tty); } else { pid_t old_pgrp = current->signal->tty_old_pgrp; if (old_pgrp) { kill_pg(old_pgrp, SIGHUP, on_exit); kill_pg(old_pgrp, SIGCONT, on_exit); } mutex_unlock(&tty_mutex); unlock_kernel(); return; } if (tty_pgrp > 0) { kill_pg(tty_pgrp, SIGHUP, on_exit); if (!on_exit) kill_pg(tty_pgrp, SIGCONT, on_exit); } spin_lock_irq(¤t->sighand->siglock); current->signal->tty_old_pgrp = 0; session = process_session(current); spin_unlock_irq(¤t->sighand->siglock); mutex_lock(&tty_mutex); /* It is possible that do_tty_hangup has free'd this tty */ tty = get_current_tty(); if (tty) { tty->session = 0; tty->pgrp = 0; } else { #ifdef TTY_DEBUG_HANGUP printk(KERN_DEBUG "error attempted to write to tty [0x%p]" " = NULL", tty); #endif } mutex_unlock(&tty_mutex); /* Now clear signal->tty under the lock */ read_lock(&tasklist_lock); session_clear_tty(session); read_unlock(&tasklist_lock); unlock_kernel(); } /** * stop_tty - propogate flow control * @tty: tty to stop * * Perform flow control to the driver. For PTY/TTY pairs we * must also propogate the TIOCKPKT status. May be called * on an already stopped device and will not re-call the driver * method. * * This functionality is used by both the line disciplines for * halting incoming flow and by the driver. It may therefore be * called from any context, may be under the tty atomic_write_lock * but not always. * * Locking: * Broken. Relies on BKL which is unsafe here. */ void stop_tty(struct tty_struct *tty) { if (tty->stopped) return; tty->stopped = 1; if (tty->link && tty->link->packet) { tty->ctrl_status &= ~TIOCPKT_START; tty->ctrl_status |= TIOCPKT_STOP; wake_up_interruptible(&tty->link->read_wait); } if (tty->driver->stop) (tty->driver->stop)(tty); } EXPORT_SYMBOL(stop_tty); /** * start_tty - propogate flow control * @tty: tty to start * * Start a tty that has been stopped if at all possible. Perform * any neccessary wakeups and propogate the TIOCPKT status. If this * is the tty was previous stopped and is being started then the * driver start method is invoked and the line discipline woken. * * Locking: * Broken. Relies on BKL which is unsafe here. */ void start_tty(struct tty_struct *tty) { if (!tty->stopped || tty->flow_stopped) return; tty->stopped = 0; if (tty->link && tty->link->packet) { tty->ctrl_status &= ~TIOCPKT_STOP; tty->ctrl_status |= TIOCPKT_START; wake_up_interruptible(&tty->link->read_wait); } if (tty->driver->start) (tty->driver->start)(tty); /* If we have a running line discipline it may need kicking */ tty_wakeup(tty); wake_up_interruptible(&tty->write_wait); } EXPORT_SYMBOL(start_tty); /** * tty_read - read method for tty device files * @file: pointer to tty file * @buf: user buffer * @count: size of user buffer * @ppos: unused * * Perform the read system call function on this terminal device. Checks * for hung up devices before calling the line discipline method. * * Locking: * Locks the line discipline internally while needed * For historical reasons the line discipline read method is * invoked under the BKL. This will go away in time so do not rely on it * in new code. Multiple read calls may be outstanding in parallel. */ static ssize_t tty_read(struct file * file, char __user * buf, size_t count, loff_t *ppos) { int i; struct tty_struct * tty; struct inode *inode; struct tty_ldisc *ld; tty = (struct tty_struct *)file->private_data; inode = file->f_path.dentry->d_inode; if (tty_paranoia_check(tty, inode, "tty_read")) return -EIO; if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags))) return -EIO; /* We want to wait for the line discipline to sort out in this situation */ ld = tty_ldisc_ref_wait(tty); lock_kernel(); if (ld->read) i = (ld->read)(tty,file,buf,count); else i = -EIO; tty_ldisc_deref(ld); unlock_kernel(); if (i > 0) inode->i_atime = current_fs_time(inode->i_sb); return i; } /* * Split writes up in sane blocksizes to avoid * denial-of-service type attacks */ static inline ssize_t do_tty_write( ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t), struct tty_struct *tty, struct file *file, const char __user *buf, size_t count) { ssize_t ret = 0, written = 0; unsigned int chunk; /* FIXME: O_NDELAY ... */ if (mutex_lock_interruptible(&tty->atomic_write_lock)) { return -ERESTARTSYS; } /* * We chunk up writes into a temporary buffer. This * simplifies low-level drivers immensely, since they * don't have locking issues and user mode accesses. * * But if TTY_NO_WRITE_SPLIT is set, we should use a * big chunk-size.. * * The default chunk-size is 2kB, because the NTTY * layer has problems with bigger chunks. It will * claim to be able to handle more characters than * it actually does. * * FIXME: This can probably go away now except that 64K chunks * are too likely to fail unless switched to vmalloc... */ chunk = 2048; if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags)) chunk = 65536; if (count < chunk) chunk = count; /* write_buf/write_cnt is protected by the atomic_write_lock mutex */ if (tty->write_cnt < chunk) { unsigned char *buf; if (chunk < 1024) chunk = 1024; buf = kmalloc(chunk, GFP_KERNEL); if (!buf) { mutex_unlock(&tty->atomic_write_lock); return -ENOMEM; } kfree(tty->write_buf); tty->write_cnt = chunk; tty->write_buf = buf; } /* Do the write .. */ for (;;) { size_t size = count; if (size > chunk) size = chunk; ret = -EFAULT; if (copy_from_user(tty->write_buf, buf, size)) break; lock_kernel(); ret = write(tty, file, tty->write_buf, size); unlock_kernel(); if (ret <= 0) break; written += ret; buf += ret; count -= ret; if (!count) break; ret = -ERESTARTSYS; if (signal_pending(current)) break; cond_resched(); } if (written) { struct inode *inode = file->f_path.dentry->d_inode; inode->i_mtime = current_fs_time(inode->i_sb); ret = written; } mutex_unlock(&tty->atomic_write_lock); return ret; } /** * tty_write - write method for tty device file * @file: tty file pointer * @buf: user data to write * @count: bytes to write * @ppos: unused * * Write data to a tty device via the line discipline. * * Locking: * Locks the line discipline as required * Writes to the tty driver are serialized by the atomic_write_lock * and are then processed in chunks to the device. The line discipline * write method will not be involked in parallel for each device * The line discipline write method is called under the big * kernel lock for historical reasons. New code should not rely on this. */ static ssize_t tty_write(struct file * file, const char __user * buf, size_t count, loff_t *ppos) { struct tty_struct * tty; struct inode *inode = file->f_path.dentry->d_inode; ssize_t ret; struct tty_ldisc *ld; tty = (struct tty_struct *)file->private_data; if (tty_paranoia_check(tty, inode, "tty_write")) return -EIO; if (!tty || !tty->driver->write || (test_bit(TTY_IO_ERROR, &tty->flags))) return -EIO; ld = tty_ldisc_ref_wait(tty); if (!ld->write) ret = -EIO; else ret = do_tty_write(ld->write, tty, file, buf, count); tty_ldisc_deref(ld); return ret; } ssize_t redirected_tty_write(struct file * file, const char __user * buf, size_t count, loff_t *ppos) { struct file *p = NULL; spin_lock(&redirect_lock); if (redirect) { get_file(redirect); p = redirect; } spin_unlock(&redirect_lock); if (p) { ssize_t res; res = vfs_write(p, buf, count, &p->f_pos); fput(p); return res; } return tty_write(file, buf, count, ppos); } static char ptychar[] = "pqrstuvwxyzabcde"; /** * pty_line_name - generate name for a pty * @driver: the tty driver in use * @index: the minor number * @p: output buffer of at least 6 bytes * * Generate a name from a driver reference and write it to the output * buffer. * * Locking: None */ static void pty_line_name(struct tty_driver *driver, int index, char *p) { int i = index + driver->name_base; /* ->name is initialized to "ttyp", but "tty" is expected */ sprintf(p, "%s%c%x", driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name, ptychar[i >> 4 & 0xf], i & 0xf); } /** * pty_line_name - generate name for a tty * @driver: the tty driver in use * @index: the minor number * @p: output buffer of at least 7 bytes * * Generate a name from a driver reference and write it to the output * buffer. * * Locking: None */ static void tty_line_name(struct tty_driver *driver, int index, char *p) { sprintf(p, "%s%d", driver->name, index + driver->name_base); } /** * init_dev - initialise a tty device * @driver: tty driver we are opening a device on * @idx: device index * @tty: returned tty structure * * Prepare a tty device. This may not be a "new" clean device but * could also be an active device. The pty drivers require special * handling because of this. * * Locking: * The function is called under the tty_mutex, which * protects us from the tty struct or driver itself going away. * * On exit the tty device has the line discipline attached and * a reference count of 1. If a pair was created for pty/tty use * and the other was a pty master then it too has a reference count of 1. * * WSH 06/09/97: Rewritten to remove races and properly clean up after a * failed open. The new code protects the open with a mutex, so it's * really quite straightforward. The mutex locking can probably be * relaxed for the (most common) case of reopening a tty. */ static int init_dev(struct tty_driver *driver, int idx, struct tty_struct **ret_tty) { struct tty_struct *tty, *o_tty; struct ktermios *tp, **tp_loc, *o_tp, **o_tp_loc; struct ktermios *ltp, **ltp_loc, *o_ltp, **o_ltp_loc; int retval = 0; /* check whether we're reopening an existing tty */ if (driver->flags & TTY_DRIVER_DEVPTS_MEM) { tty = devpts_get_tty(idx); /* * If we don't have a tty here on a slave open, it's because * the master already started the close process and there's * no relation between devpts file and tty anymore. */ if (!tty && driver->subtype == PTY_TYPE_SLAVE) { retval = -EIO; goto end_init; } /* * It's safe from now on because init_dev() is called with * tty_mutex held and release_dev() won't change tty->count * or tty->flags without having to grab tty_mutex */ if (tty && driver->subtype == PTY_TYPE_MASTER) tty = tty->link; } else { tty = driver->ttys[idx]; } if (tty) goto fast_track; /* * First time open is complex, especially for PTY devices. * This code guarantees that either everything succeeds and the * TTY is ready for operation, or else the table slots are vacated * and the allocated memory released. (Except that the termios * and locked termios may be retained.) */ if (!try_module_get(driver->owner)) { retval = -ENODEV; goto end_init; } o_tty = NULL; tp = o_tp = NULL; ltp = o_ltp = NULL; tty = alloc_tty_struct(); if(!tty) goto fail_no_mem; initialize_tty_struct(tty); tty->driver = driver; tty->index = idx; tty_line_name(driver, idx, tty->name); if (driver->flags & TTY_DRIVER_DEVPTS_MEM) { tp_loc = &tty->termios; ltp_loc = &tty->termios_locked; } else { tp_loc = &driver->termios[idx]; ltp_loc = &driver->termios_locked[idx]; } if (!*tp_loc) { tp = (struct ktermios *) kmalloc(sizeof(struct ktermios), GFP_KERNEL); if (!tp) goto free_mem_out; *tp = driver->init_termios; } if (!*ltp_loc) { ltp = (struct ktermios *) kmalloc(sizeof(struct ktermios), GFP_KERNEL); if (!ltp) goto free_mem_out; memset(ltp, 0, sizeof(struct ktermios)); } if (driver->type == TTY_DRIVER_TYPE_PTY) { o_tty = alloc_tty_struct(); if (!o_tty) goto free_mem_out; initialize_tty_struct(o_tty); o_tty->driver = driver->other; o_tty->index = idx; tty_line_name(driver->other, idx, o_tty->name); if (driver->flags & TTY_DRIVER_DEVPTS_MEM) { o_tp_loc = &o_tty->termios; o_ltp_loc = &o_tty->termios_locked; } else { o_tp_loc = &driver->other->termios[idx]; o_ltp_loc = &driver->other->termios_locked[idx]; } if (!*o_tp_loc) { o_tp = (struct ktermios *) kmalloc(sizeof(struct ktermios), GFP_KERNEL); if (!o_tp) goto free_mem_out; *o_tp = driver->other->init_termios; } if (!*o_ltp_loc) { o_ltp = (struct ktermios *) kmalloc(sizeof(struct ktermios), GFP_KERNEL); if (!o_ltp) goto free_mem_out; memset(o_ltp, 0, sizeof(struct ktermios)); } /* * Everything allocated ... set up the o_tty structure. */ if (!(driver->other->flags & TTY_DRIVER_DEVPTS_MEM)) { driver->other->ttys[idx] = o_tty; } if (!*o_tp_loc) *o_tp_loc = o_tp; if (!*o_ltp_loc) *o_ltp_loc = o_ltp; o_tty->termios = *o_tp_loc; o_tty->termios_locked = *o_ltp_loc; driver->other->refcount++; if (driver->subtype == PTY_TYPE_MASTER) o_tty->count++; /* Establish the links in both directions */ tty->link = o_tty; o_tty->link = tty; } /* * All structures have been allocated, so now we install them. * Failures after this point use release_mem to clean up, so * there's no need to null out the local pointers. */ if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM)) { driver->ttys[idx] = tty; } if (!*tp_loc) *tp_loc = tp; if (!*ltp_loc) *ltp_loc = ltp; tty->termios = *tp_loc; tty->termios_locked = *ltp_loc; /* Compatibility until drivers always set this */ tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios); tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios); driver->refcount++; tty->count++; /* * Structures all installed ... call the ldisc open routines. * If we fail here just call release_mem to clean up. No need * to decrement the use counts, as release_mem doesn't care. */ if (tty->ldisc.open) { retval = (tty->ldisc.open)(tty); if (retval) goto release_mem_out; } if (o_tty && o_tty->ldisc.open) { retval = (o_tty->ldisc.open)(o_tty); if (retval) { if (tty->ldisc.close) (tty->ldisc.close)(tty); goto release_mem_out; } tty_ldisc_enable(o_tty); } tty_ldisc_enable(tty); goto success; /* * This fast open can be used if the tty is already open. * No memory is allocated, and the only failures are from * attempting to open a closing tty or attempting multiple * opens on a pty master. */ fast_track: if (test_bit(TTY_CLOSING, &tty->flags)) { retval = -EIO; goto end_init; } if (driver->type == TTY_DRIVER_TYPE_PTY && driver->subtype == PTY_TYPE_MASTER) { /* * special case for PTY masters: only one open permitted, * and the slave side open count is incremented as well. */ if (tty->count) { retval = -EIO; goto end_init; } tty->link->count++; } tty->count++; tty->driver = driver; /* N.B. why do this every time?? */ /* FIXME */ if(!test_bit(TTY_LDISC, &tty->flags)) printk(KERN_ERR "init_dev but no ldisc\n"); success: *ret_tty = tty; /* All paths come through here to release the mutex */ end_init: return retval; /* Release locally allocated memory ... nothing placed in slots */ free_mem_out: kfree(o_tp); if (o_tty) free_tty_struct(o_tty); kfree(ltp); kfree(tp); free_tty_struct(tty); fail_no_mem: module_put(driver->owner); retval = -ENOMEM; goto end_init; /* call the tty release_mem routine to clean out this slot */ release_mem_out: if (printk_ratelimit()) printk(KERN_INFO "init_dev: ldisc open failed, " "clearing slot %d\n", idx); release_mem(tty, idx); goto end_init; } /** * release_mem - release tty structure memory * * Releases memory associated with a tty structure, and clears out the * driver table slots. This function is called when a device is no longer * in use. It also gets called when setup of a device fails. * * Locking: * tty_mutex - sometimes only * takes the file list lock internally when working on the list * of ttys that the driver keeps. * FIXME: should we require tty_mutex is held here ?? */ static void release_mem(struct tty_struct *tty, int idx) { struct tty_struct *o_tty; struct ktermios *tp; int devpts = tty->driver->flags & TTY_DRIVER_DEVPTS_MEM; if ((o_tty = tty->link) != NULL) { if (!devpts) o_tty->driver->ttys[idx] = NULL; if (o_tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) { tp = o_tty->termios; if (!devpts) o_tty->driver->termios[idx] = NULL; kfree(tp); tp = o_tty->termios_locked; if (!devpts) o_tty->driver->termios_locked[idx] = NULL; kfree(tp); } o_tty->magic = 0; o_tty->driver->refcount--; file_list_lock(); list_del_init(&o_tty->tty_files); file_list_unlock(); free_tty_struct(o_tty); } if (!devpts) tty->driver->ttys[idx] = NULL; if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) { tp = tty->termios; if (!devpts) tty->driver->termios[idx] = NULL; kfree(tp); tp = tty->termios_locked; if (!devpts) tty->driver->termios_locked[idx] = NULL; kfree(tp); } tty->magic = 0; tty->driver->refcount--; file_list_lock(); list_del_init(&tty->tty_files); file_list_unlock(); module_put(tty->driver->owner); free_tty_struct(tty); } /* * Even releasing the tty structures is a tricky business.. We have * to be very careful that the structures are all released at the * same time, as interrupts might otherwise get the wrong pointers. * * WSH 09/09/97: rewritten to avoid some nasty race conditions that could * lead to double frees or releasing memory still in use. */ static void release_dev(struct file * filp) { struct tty_struct *tty, *o_tty; int pty_master, tty_closing, o_tty_closing, do_sleep; int devpts; int idx; char buf[64]; unsigned long flags; tty = (struct tty_struct *)filp->private_data; if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "release_dev")) return; check_tty_count(tty, "release_dev"); tty_fasync(-1, filp, 0); idx = tty->index; pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY && tty->driver->subtype == PTY_TYPE_MASTER); devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0; o_tty = tty->link; #ifdef TTY_PARANOIA_CHECK if (idx < 0 || idx >= tty->driver->num) { printk(KERN_DEBUG "release_dev: bad idx when trying to " "free (%s)\n", tty->name); return; } if (!(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) { if (tty != tty->driver->ttys[idx]) { printk(KERN_DEBUG "release_dev: driver.table[%d] not tty " "for (%s)\n", idx, tty->name); return; } if (tty->termios != tty->driver->termios[idx]) { printk(KERN_DEBUG "release_dev: driver.termios[%d] not termios " "for (%s)\n", idx, tty->name); return; } if (tty->termios_locked != tty->driver->termios_locked[idx]) { printk(KERN_DEBUG "release_dev: driver.termios_locked[%d] not " "termios_locked for (%s)\n", idx, tty->name); return; } } #endif #ifdef TTY_DEBUG_HANGUP printk(KERN_DEBUG "release_dev of %s (tty count=%d)...", tty_name(tty, buf), tty->count); #endif #ifdef TTY_PARANOIA_CHECK if (tty->driver->other && !(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) { if (o_tty != tty->driver->other->ttys[idx]) { printk(KERN_DEBUG "release_dev: other->table[%d] " "not o_tty for (%s)\n", idx, tty->name); return; } if (o_tty->termios != tty->driver->other->termios[idx]) { printk(KERN_DEBUG "release_dev: other->termios[%d] " "not o_termios for (%s)\n", idx, tty->name); return; } if (o_tty->termios_locked != tty->driver->other->termios_locked[idx]) { printk(KERN_DEBUG "release_dev: other->termios_locked[" "%d] not o_termios_locked for (%s)\n", idx, tty->name); return; } if (o_tty->link != tty) { printk(KERN_DEBUG "release_dev: bad pty pointers\n"); return; } } #endif if (tty->driver->close) tty->driver->close(tty, filp); /* * Sanity check: if tty->count is going to zero, there shouldn't be * any waiters on tty->read_wait or tty->write_wait. We test the * wait queues and kick everyone out _before_ actually starting to * close. This ensures that we won't block while releasing the tty * structure. * * The test for the o_tty closing is necessary, since the master and * slave sides may close in any order. If the slave side closes out * first, its count will be one, since the master side holds an open. * Thus this test wouldn't be triggered at the time the slave closes, * so we do it now. * * Note that it's possible for the tty to be opened again while we're * flushing out waiters. By recalculating the closing flags before * each iteration we avoid any problems. */ while (1) { /* Guard against races with tty->count changes elsewhere and opens on /dev/tty */ mutex_lock(&tty_mutex); tty_closing = tty->count <= 1; o_tty_closing = o_tty && (o_tty->count <= (pty_master ? 1 : 0)); do_sleep = 0; if (tty_closing) { if (waitqueue_active(&tty->read_wait)) { wake_up(&tty->read_wait); do_sleep++; } if (waitqueue_active(&tty->write_wait)) { wake_up(&tty->write_wait); do_sleep++; } } if (o_tty_closing) { if (waitqueue_active(&o_tty->read_wait)) { wake_up(&o_tty->read_wait); do_sleep++; } if (waitqueue_active(&o_tty->write_wait)) { wake_up(&o_tty->write_wait); do_sleep++; } } if (!do_sleep) break; printk(KERN_WARNING "release_dev: %s: read/write wait queue " "active!\n", tty_name(tty, buf)); mutex_unlock(&tty_mutex); schedule(); } /* * The closing flags are now consistent with the open counts on * both sides, and we've completed the last operation that could * block, so it's safe to proceed with closing. */ if (pty_master) { if (--o_tty->count < 0) { printk(KERN_WARNING "release_dev: bad pty slave count " "(%d) for %s\n", o_tty->count, tty_name(o_tty, buf)); o_tty->count = 0; } } if (--tty->count < 0) { printk(KERN_WARNING "release_dev: bad tty->count (%d) for %s\n", tty->count, tty_name(tty, buf)); tty->count = 0; } /* * We've decremented tty->count, so we need to remove this file * descriptor off the tty->tty_files list; this serves two * purposes: * - check_tty_count sees the correct number of file descriptors * associated with this tty. * - do_tty_hangup no longer sees this file descriptor as * something that needs to be handled for hangups. */ file_kill(filp); filp->private_data = NULL; /* * Perform some housekeeping before deciding whether to return. * * Set the TTY_CLOSING flag if this was the last open. In the * case of a pty we may have to wait around for the other side * to close, and TTY_CLOSING makes sure we can't be reopened. */ if(tty_closing) set_bit(TTY_CLOSING, &tty->flags); if(o_tty_closing) set_bit(TTY_CLOSING, &o_tty->flags); /* * If _either_ side is closing, make sure there aren't any * processes that still think tty or o_tty is their controlling * tty. */ if (tty_closing || o_tty_closing) { read_lock(&tasklist_lock); session_clear_tty(tty->session); if (o_tty) session_clear_tty(o_tty->session); read_unlock(&tasklist_lock); } mutex_unlock(&tty_mutex); /* check whether both sides are closing ... */ if (!tty_closing || (o_tty && !o_tty_closing)) return; #ifdef TTY_DEBUG_HANGUP printk(KERN_DEBUG "freeing tty structure..."); #endif /* * Prevent flush_to_ldisc() from rescheduling the work for later. Then * kill any delayed work. As this is the final close it does not * race with the set_ldisc code path. */ clear_bit(TTY_LDISC, &tty->flags); cancel_delayed_work(&tty->buf.work); /* * Wait for ->hangup_work and ->buf.work handlers to terminate */ flush_scheduled_work(); /* * Wait for any short term users (we know they are just driver * side waiters as the file is closing so user count on the file * side is zero. */ spin_lock_irqsave(&tty_ldisc_lock, flags); while(tty->ldisc.refcount) { spin_unlock_irqrestore(&tty_ldisc_lock, flags); wait_event(tty_ldisc_wait, tty->ldisc.refcount == 0); spin_lock_irqsave(&tty_ldisc_lock, flags); } spin_unlock_irqrestore(&tty_ldisc_lock, flags); /* * Shutdown the current line discipline, and reset it to N_TTY. * N.B. why reset ldisc when we're releasing the memory?? * * FIXME: this MUST get fixed for the new reflocking */ if (tty->ldisc.close) (tty->ldisc.close)(tty); tty_ldisc_put(tty->ldisc.num); /* * Switch the line discipline back */ tty_ldisc_assign(tty, tty_ldisc_get(N_TTY)); tty_set_termios_ldisc(tty,N_TTY); if (o_tty) { /* FIXME: could o_tty be in setldisc here ? */ clear_bit(TTY_LDISC, &o_tty->flags); if (o_tty->ldisc.close) (o_tty->ldisc.close)(o_tty); tty_ldisc_put(o_tty->ldisc.num); tty_ldisc_assign(o_tty, tty_ldisc_get(N_TTY)); tty_set_termios_ldisc(o_tty,N_TTY); } /* * The release_mem function takes care of the details of clearing * the slots and preserving the termios structure. */ release_mem(tty, idx); #ifdef CONFIG_UNIX98_PTYS /* Make this pty number available for reallocation */ if (devpts) { down(&allocated_ptys_lock); idr_remove(&allocated_ptys, idx); up(&allocated_ptys_lock); } #endif } /** * tty_open - open a tty device * @inode: inode of device file * @filp: file pointer to tty * * tty_open and tty_release keep up the tty count that contains the * number of opens done on a tty. We cannot use the inode-count, as * different inodes might point to the same tty. * * Open-counting is needed for pty masters, as well as for keeping * track of serial lines: DTR is dropped when the last close happens. * (This is not done solely through tty->count, now. - Ted 1/27/92) * * The termios state of a pty is reset on first open so that * settings don't persist across reuse. * * Locking: tty_mutex protects tty, get_tty_driver and init_dev work. * tty->count should protect the rest. * ->siglock protects ->signal/->sighand */ static int tty_open(struct inode * inode, struct file * filp) { struct tty_struct *tty; int noctty, retval; struct tty_driver *driver; int index; dev_t device = inode->i_rdev; unsigned short saved_flags = filp->f_flags; nonseekable_open(inode, filp); retry_open: noctty = filp->f_flags & O_NOCTTY; index = -1; retval = 0; mutex_lock(&tty_mutex); if (device == MKDEV(TTYAUX_MAJOR,0)) { tty = get_current_tty(); if (!tty) { mutex_unlock(&tty_mutex); return -ENXIO; } driver = tty->driver; index = tty->index; filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */ /* noctty = 1; */ goto got_driver; } #ifdef CONFIG_VT if (device == MKDEV(TTY_MAJOR,0)) { extern struct tty_driver *console_driver; driver = console_driver; index = fg_console; noctty = 1; goto got_driver; } #endif if (device == MKDEV(TTYAUX_MAJOR,1)) { driver = console_device(&index); if (driver) { /* Don't let /dev/console block */ filp->f_flags |= O_NONBLOCK; noctty = 1; goto got_driver; } mutex_unlock(&tty_mutex); return -ENODEV; } driver = get_tty_driver(device, &index); if (!driver) { mutex_unlock(&tty_mutex); return -ENODEV; } got_driver: retval = init_dev(driver, index, &tty); mutex_unlock(&tty_mutex); if (retval) return retval; filp->private_data = tty; file_move(filp, &tty->tty_files); check_tty_count(tty, "tty_open"); if (tty->driver->type == TTY_DRIVER_TYPE_PTY && tty->driver->subtype == PTY_TYPE_MASTER) noctty = 1; #ifdef TTY_DEBUG_HANGUP printk(KERN_DEBUG "opening %s...", tty->name); #endif if (!retval) { if (tty->driver->open) retval = tty->driver->open(tty, filp); else retval = -ENODEV; } filp->f_flags = saved_flags; if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN)) retval = -EBUSY; if (retval) { #ifdef TTY_DEBUG_HANGUP printk(KERN_DEBUG "error %d in opening %s...", retval, tty->name); #endif release_dev(filp); if (retval != -ERESTARTSYS) return retval; if (signal_pending(current)) return retval; schedule(); /* * Need to reset f_op in case a hangup happened. */ if (filp->f_op == &hung_up_tty_fops) filp->f_op = &tty_fops; goto retry_open; } mutex_lock(&tty_mutex); spin_lock_irq(¤t->sighand->siglock); if (!noctty && current->signal->leader && !current->signal->tty && tty->session == 0) __proc_set_tty(current, tty); spin_unlock_irq(¤t->sighand->siglock); mutex_unlock(&tty_mutex); return 0; } #ifdef CONFIG_UNIX98_PTYS /** * ptmx_open - open a unix 98 pty master * @inode: inode of device file * @filp: file pointer to tty * * Allocate a unix98 pty master device from the ptmx driver. * * Locking: tty_mutex protects theinit_dev work. tty->count should protect the rest. * allocated_ptys_lock handles the list of free pty numbers */ static int ptmx_open(struct inode * inode, struct file * filp) { struct tty_struct *tty; int retval; int index; int idr_ret; nonseekable_open(inode, filp); /* find a device that is not in use. */ down(&allocated_ptys_lock); if (!idr_pre_get(&allocated_ptys, GFP_KERNEL)) { up(&allocated_ptys_lock); return -ENOMEM; } idr_ret = idr_get_new(&allocated_ptys, NULL, &index); if (idr_ret < 0) { up(&allocated_ptys_lock); if (idr_ret == -EAGAIN) return -ENOMEM; return -EIO; } if (index >= pty_limit) { idr_remove(&allocated_ptys, index); up(&allocated_ptys_lock); return -EIO; } up(&allocated_ptys_lock); mutex_lock(&tty_mutex); retval = init_dev(ptm_driver, index, &tty); mutex_unlock(&tty_mutex); if (retval) goto out; set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */ filp->private_data = tty; file_move(filp, &tty->tty_files); retval = -ENOMEM; if (devpts_pty_new(tty->link)) goto out1; check_tty_count(tty, "tty_open"); retval = ptm_driver->open(tty, filp); if (!retval) return 0; out1: release_dev(filp); return retval; out: down(&allocated_ptys_lock); idr_remove(&allocated_ptys, index); up(&allocated_ptys_lock); return retval; } #endif /** * tty_release - vfs callback for close * @inode: inode of tty * @filp: file pointer for handle to tty * * Called the last time each file handle is closed that references * this tty. There may however be several such references. * * Locking: * Takes bkl. See release_dev */ static int tty_release(struct inode * inode, struct file * filp) { lock_kernel(); release_dev(filp); unlock_kernel(); return 0; } /** * tty_poll - check tty status * @filp: file being polled * @wait: poll wait structures to update * * Call the line discipline polling method to obtain the poll * status of the device. * * Locking: locks called line discipline but ldisc poll method * may be re-entered freely by other callers. */ static unsigned int tty_poll(struct file * filp, poll_table * wait) { struct tty_struct * tty; struct tty_ldisc *ld; int ret = 0; tty = (struct tty_struct *)filp->private_data; if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_poll")) return 0; ld = tty_ldisc_ref_wait(tty); if (ld->poll) ret = (ld->poll)(tty, filp, wait); tty_ldisc_deref(ld); return ret; } static int tty_fasync(int fd, struct file * filp, int on) { struct tty_struct * tty; int retval; tty = (struct tty_struct *)filp->private_data; if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_fasync")) return 0; retval = fasync_helper(fd, filp, on, &tty->fasync); if (retval <= 0) return retval; if (on) { if (!waitqueue_active(&tty->read_wait)) tty->minimum_to_wake = 1; retval = f_setown(filp, (-tty->pgrp) ? : current->pid, 0); if (retval) return retval; } else { if (!tty->fasync && !waitqueue_active(&tty->read_wait)) tty->minimum_to_wake = N_TTY_BUF_SIZE; } return 0; } /** * tiocsti - fake input character * @tty: tty to fake input into * @p: pointer to character * * Fake input to a tty device. Does the neccessary locking and * input management. * * FIXME: does not honour flow control ?? * * Locking: * Called functions take tty_ldisc_lock * current->signal->tty check is safe without locks * * FIXME: may race normal receive processing */ static int tiocsti(struct tty_struct *tty, char __user *p) { char ch, mbz = 0; struct tty_ldisc *ld; if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN)) return -EPERM; if (get_user(ch, p)) return -EFAULT; ld = tty_ldisc_ref_wait(tty); ld->receive_buf(tty, &ch, &mbz, 1); tty_ldisc_deref(ld); return 0; } /** * tiocgwinsz - implement window query ioctl * @tty; tty * @arg: user buffer for result * * Copies the kernel idea of the window size into the user buffer. * * Locking: tty->termios_mutex is taken to ensure the winsize data * is consistent. */ static int tiocgwinsz(struct tty_struct *tty, struct winsize __user * arg) { int err; mutex_lock(&tty->termios_mutex); err = copy_to_user(arg, &tty->winsize, sizeof(*arg)); mutex_unlock(&tty->termios_mutex); return err ? -EFAULT: 0; } /** * tiocswinsz - implement window size set ioctl * @tty; tty * @arg: user buffer for result * * Copies the user idea of the window size to the kernel. Traditionally * this is just advisory information but for the Linux console it * actually has driver level meaning and triggers a VC resize. * * Locking: * Called function use the console_sem is used to ensure we do * not try and resize the console twice at once. * The tty->termios_mutex is used to ensure we don't double * resize and get confused. Lock order - tty->termios_mutex before * console sem */ static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty, struct winsize __user * arg) { struct winsize tmp_ws; if (copy_from_user(&tmp_ws, arg, sizeof(*arg))) return -EFAULT; mutex_lock(&tty->termios_mutex); if (!memcmp(&tmp_ws, &tty->winsize, sizeof(*arg))) goto done; #ifdef CONFIG_VT if (tty->driver->type == TTY_DRIVER_TYPE_CONSOLE) { if (vc_lock_resize(tty->driver_data, tmp_ws.ws_col, tmp_ws.ws_row)) { mutex_unlock(&tty->termios_mutex); return -ENXIO; } } #endif if (tty->pgrp > 0) kill_pg(tty->pgrp, SIGWINCH, 1); if ((real_tty->pgrp != tty->pgrp) && (real_tty->pgrp > 0)) kill_pg(real_tty->pgrp, SIGWINCH, 1); tty->winsize = tmp_ws; real_tty->winsize = tmp_ws; done: mutex_unlock(&tty->termios_mutex); return 0; } /** * tioccons - allow admin to move logical console * @file: the file to become console * * Allow the adminstrator to move the redirected console device * * Locking: uses redirect_lock to guard the redirect information */ static int tioccons(struct file *file) { if (!capable(CAP_SYS_ADMIN)) return -EPERM; if (file->f_op->write == redirected_tty_write) { struct file *f; spin_lock(&redirect_lock); f = redirect; redirect = NULL; spin_unlock(&redirect_lock); if (f) fput(f); return 0; } spin_lock(&redirect_lock); if (redirect) { spin_unlock(&redirect_lock); return -EBUSY; } get_file(file); redirect = file; spin_unlock(&redirect_lock); return 0; } /** * fionbio - non blocking ioctl * @file: file to set blocking value * @p: user parameter * * Historical tty interfaces had a blocking control ioctl before * the generic functionality existed. This piece of history is preserved * in the expected tty API of posix OS's. * * Locking: none, the open fle handle ensures it won't go away. */ static int fionbio(struct file *file, int __user *p) { int nonblock; if (get_user(nonblock, p)) return -EFAULT; if (nonblock) file->f_flags |= O_NONBLOCK; else file->f_flags &= ~O_NONBLOCK; return 0; } /** * tiocsctty - set controlling tty * @tty: tty structure * @arg: user argument * * This ioctl is used to manage job control. It permits a session * leader to set this tty as the controlling tty for the session. * * Locking: * Takes tty_mutex() to protect tty instance * Takes tasklist_lock internally to walk sessions * Takes ->siglock() when updating signal->tty */ static int tiocsctty(struct tty_struct *tty, int arg) { int ret = 0; if (current->signal->leader && (process_session(current) == tty->session)) return ret; mutex_lock(&tty_mutex); /* * The process must be a session leader and * not have a controlling tty already. */ if (!current->signal->leader || current->signal->tty) { ret = -EPERM; goto unlock; } if (tty->session > 0) { /* * This tty is already the controlling * tty for another session group! */ if ((arg == 1) && capable(CAP_SYS_ADMIN)) { /* * Steal it away */ read_lock(&tasklist_lock); session_clear_tty(tty->session); read_unlock(&tasklist_lock); } else { ret = -EPERM; goto unlock; } } proc_set_tty(current, tty); unlock: mutex_unlock(&tty_mutex); return ret; } /** * tiocgpgrp - get process group * @tty: tty passed by user * @real_tty: tty side of the tty pased by the user if a pty else the tty * @p: returned pid * * Obtain the process group of the tty. If there is no process group * return an error. * * Locking: none. Reference to current->signal->tty is safe. */ static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p) { /* * (tty == real_tty) is a cheap way of * testing if the tty is NOT a master pty. */ if (tty == real_tty && current->signal->tty != real_tty) return -ENOTTY; return put_user(real_tty->pgrp, p); } /** * tiocspgrp - attempt to set process group * @tty: tty passed by user * @real_tty: tty side device matching tty passed by user * @p: pid pointer * * Set the process group of the tty to the session passed. Only * permitted where the tty session is our session. * * Locking: None */ static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p) { pid_t pgrp; int retval = tty_check_change(real_tty); if (retval == -EIO) return -ENOTTY; if (retval) return retval; if (!current->signal->tty || (current->signal->tty != real_tty) || (real_tty->session != process_session(current))) return -ENOTTY; if (get_user(pgrp, p)) return -EFAULT; if (pgrp < 0) return -EINVAL; if (session_of_pgrp(pgrp) != process_session(current)) return -EPERM; real_tty->pgrp = pgrp; return 0; } /** * tiocgsid - get session id * @tty: tty passed by user * @real_tty: tty side of the tty pased by the user if a pty else the tty * @p: pointer to returned session id * * Obtain the session id of the tty. If there is no session * return an error. * * Locking: none. Reference to current->signal->tty is safe. */ static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p) { /* * (tty == real_tty) is a cheap way of * testing if the tty is NOT a master pty. */ if (tty == real_tty && current->signal->tty != real_tty) return -ENOTTY; if (real_tty->session <= 0) return -ENOTTY; return put_user(real_tty->session, p); } /** * tiocsetd - set line discipline * @tty: tty device * @p: pointer to user data * * Set the line discipline according to user request. * * Locking: see tty_set_ldisc, this function is just a helper */ static int tiocsetd(struct tty_struct *tty, int __user *p) { int ldisc; if (get_user(ldisc, p)) return -EFAULT; return tty_set_ldisc(tty, ldisc); } /** * send_break - performed time break * @tty: device to break on * @duration: timeout in mS * * Perform a timed break on hardware that lacks its own driver level * timed break functionality. * * Locking: * atomic_write_lock serializes * */ static int send_break(struct tty_struct *tty, unsigned int duration) { if (mutex_lock_interruptible(&tty->atomic_write_lock)) return -EINTR; tty->driver->break_ctl(tty, -1); if (!signal_pending(current)) { msleep_interruptible(duration); } tty->driver->break_ctl(tty, 0); mutex_unlock(&tty->atomic_write_lock); if (signal_pending(current)) return -EINTR; return 0; } /** * tiocmget - get modem status * @tty: tty device * @file: user file pointer * @p: pointer to result * * Obtain the modem status bits from the tty driver if the feature * is supported. Return -EINVAL if it is not available. * * Locking: none (up to the driver) */ static int tty_tiocmget(struct tty_struct *tty, struct file *file, int __user *p) { int retval = -EINVAL; if (tty->driver->tiocmget) { retval = tty->driver->tiocmget(tty, file); if (retval >= 0) retval = put_user(retval, p); } return retval; } /** * tiocmset - set modem status * @tty: tty device * @file: user file pointer * @cmd: command - clear bits, set bits or set all * @p: pointer to desired bits * * Set the modem status bits from the tty driver if the feature * is supported. Return -EINVAL if it is not available. * * Locking: none (up to the driver) */ static int tty_tiocmset(struct tty_struct *tty, struct file *file, unsigned int cmd, unsigned __user *p) { int retval = -EINVAL; if (tty->driver->tiocmset) { unsigned int set, clear, val; retval = get_user(val, p); if (retval) return retval; set = clear = 0; switch (cmd) { case TIOCMBIS: set = val; break; case TIOCMBIC: clear = val; break; case TIOCMSET: set = val; clear = ~val; break; } set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP; clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP; retval = tty->driver->tiocmset(tty, file, set, clear); } return retval; } /* * Split this up, as gcc can choke on it otherwise.. */ int tty_ioctl(struct inode * inode, struct file * file, unsigned int cmd, unsigned long arg) { struct tty_struct *tty, *real_tty; void __user *p = (void __user *)arg; int retval; struct tty_ldisc *ld; tty = (struct tty_struct *)file->private_data; if (tty_paranoia_check(tty, inode, "tty_ioctl")) return -EINVAL; /* CHECKME: is this safe as one end closes ? */ real_tty = tty; if (tty->driver->type == TTY_DRIVER_TYPE_PTY && tty->driver->subtype == PTY_TYPE_MASTER) real_tty = tty->link; /* * Break handling by driver */ if (!tty->driver->break_ctl) { switch(cmd) { case TIOCSBRK: case TIOCCBRK: if (tty->driver->ioctl) return tty->driver->ioctl(tty, file, cmd, arg); return -EINVAL; /* These two ioctl's always return success; even if */ /* the driver doesn't support them. */ case TCSBRK: case TCSBRKP: if (!tty->driver->ioctl) return 0; retval = tty->driver->ioctl(tty, file, cmd, arg); if (retval == -ENOIOCTLCMD) retval = 0; return retval; } } /* * Factor out some common prep work */ switch (cmd) { case TIOCSETD: case TIOCSBRK: case TIOCCBRK: case TCSBRK: case TCSBRKP: retval = tty_check_change(tty); if (retval) return retval; if (cmd != TIOCCBRK) { tty_wait_until_sent(tty, 0); if (signal_pending(current)) return -EINTR; } break; } switch (cmd) { case TIOCSTI: return tiocsti(tty, p); case TIOCGWINSZ: return tiocgwinsz(tty, p); case TIOCSWINSZ: return tiocswinsz(tty, real_tty, p); case TIOCCONS: return real_tty!=tty ? -EINVAL : tioccons(file); case FIONBIO: return fionbio(file, p); case TIOCEXCL: set_bit(TTY_EXCLUSIVE, &tty->flags); return 0; case TIOCNXCL: clear_bit(TTY_EXCLUSIVE, &tty->flags); return 0; case TIOCNOTTY: if (current->signal->tty != tty) return -ENOTTY; if (current->signal->leader) disassociate_ctty(0); proc_clear_tty(current); return 0; case TIOCSCTTY: return tiocsctty(tty, arg); case TIOCGPGRP: return tiocgpgrp(tty, real_tty, p); case TIOCSPGRP: return tiocspgrp(tty, real_tty, p); case TIOCGSID: return tiocgsid(tty, real_tty, p); case TIOCGETD: /* FIXME: check this is ok */ return put_user(tty->ldisc.num, (int __user *)p); case TIOCSETD: return tiocsetd(tty, p); #ifdef CONFIG_VT case TIOCLINUX: return tioclinux(tty, arg); #endif /* * Break handling */ case TIOCSBRK: /* Turn break on, unconditionally */ tty->driver->break_ctl(tty, -1); return 0; case TIOCCBRK: /* Turn break off, unconditionally */ tty->driver->break_ctl(tty, 0); return 0; case TCSBRK: /* SVID version: non-zero arg --> no break */ /* non-zero arg means wait for all output data * to be sent (performed above) but don't send break. * This is used by the tcdrain() termios function. */ if (!arg) return send_break(tty, 250); return 0; case TCSBRKP: /* support for POSIX tcsendbreak() */ return send_break(tty, arg ? arg*100 : 250); case TIOCMGET: return tty_tiocmget(tty, file, p); case TIOCMSET: case TIOCMBIC: case TIOCMBIS: return tty_tiocmset(tty, file, cmd, p); } if (tty->driver->ioctl) { retval = (tty->driver->ioctl)(tty, file, cmd, arg); if (retval != -ENOIOCTLCMD) return retval; } ld = tty_ldisc_ref_wait(tty); retval = -EINVAL; if (ld->ioctl) { retval = ld->ioctl(tty, file, cmd, arg); if (retval == -ENOIOCTLCMD) retval = -EINVAL; } tty_ldisc_deref(ld); return retval; } /* * This implements the "Secure Attention Key" --- the idea is to * prevent trojan horses by killing all processes associated with this * tty when the user hits the "Secure Attention Key". Required for * super-paranoid applications --- see the Orange Book for more details. * * This code could be nicer; ideally it should send a HUP, wait a few * seconds, then send a INT, and then a KILL signal. But you then * have to coordinate with the init process, since all processes associated * with the current tty must be dead before the new getty is allowed * to spawn. * * Now, if it would be correct ;-/ The current code has a nasty hole - * it doesn't catch files in flight. We may send the descriptor to ourselves * via AF_UNIX socket, close it and later fetch from socket. FIXME. * * Nasty bug: do_SAK is being called in interrupt context. This can * deadlock. We punt it up to process context. AKPM - 16Mar2001 */ static void __do_SAK(struct work_struct *work) { struct tty_struct *tty = container_of(work, struct tty_struct, SAK_work); #ifdef TTY_SOFT_SAK tty_hangup(tty); #else struct task_struct *g, *p; int session; int i; struct file *filp; struct fdtable *fdt; if (!tty) return; session = tty->session; tty_ldisc_flush(tty); if (tty->driver->flush_buffer) tty->driver->flush_buffer(tty); read_lock(&tasklist_lock); /* Kill the entire session */ do_each_task_pid(session, PIDTYPE_SID, p) { printk(KERN_NOTICE "SAK: killed process %d" " (%s): process_session(p)==tty->session\n", p->pid, p->comm); send_sig(SIGKILL, p, 1); } while_each_task_pid(session, PIDTYPE_SID, p); /* Now kill any processes that happen to have the * tty open. */ do_each_thread(g, p) { if (p->signal->tty == tty) { printk(KERN_NOTICE "SAK: killed process %d" " (%s): process_session(p)==tty->session\n", p->pid, p->comm); send_sig(SIGKILL, p, 1); continue; } task_lock(p); if (p->files) { /* * We don't take a ref to the file, so we must * hold ->file_lock instead. */ spin_lock(&p->files->file_lock); fdt = files_fdtable(p->files); for (i=0; i < fdt->max_fds; i++) { filp = fcheck_files(p->files, i); if (!filp) continue; if (filp->f_op->read == tty_read && filp->private_data == tty) { printk(KERN_NOTICE "SAK: killed process %d" " (%s): fd#%d opened to the tty\n", p->pid, p->comm, i); force_sig(SIGKILL, p); break; } } spin_unlock(&p->files->file_lock); } task_unlock(p); } while_each_thread(g, p); read_unlock(&tasklist_lock); #endif } /* * The tq handling here is a little racy - tty->SAK_work may already be queued. * Fortunately we don't need to worry, because if ->SAK_work is already queued, * the values which we write to it will be identical to the values which it * already has. --akpm */ void do_SAK(struct tty_struct *tty) { if (!tty) return; PREPARE_WORK(&tty->SAK_work, __do_SAK); schedule_work(&tty->SAK_work); } EXPORT_SYMBOL(do_SAK); /** * flush_to_ldisc * @work: tty structure passed from work queue. * * This routine is called out of the software interrupt to flush data * from the buffer chain to the line discipline. * * Locking: holds tty->buf.lock to guard buffer list. Drops the lock * while invoking the line discipline receive_buf method. The * receive_buf method is single threaded for each tty instance. */ static void flush_to_ldisc(struct work_struct *work) { struct tty_struct *tty = container_of(work, struct tty_struct, buf.work.work); unsigned long flags; struct tty_ldisc *disc; struct tty_buffer *tbuf, *head; char *char_buf; unsigned char *flag_buf; disc = tty_ldisc_ref(tty); if (disc == NULL) /* !TTY_LDISC */ return; spin_lock_irqsave(&tty->buf.lock, flags); head = tty->buf.head; if (head != NULL) { tty->buf.head = NULL; for (;;) { int count = head->commit - head->read; if (!count) { if (head->next == NULL) break; tbuf = head; head = head->next; tty_buffer_free(tty, tbuf); continue; } if (!tty->receive_room) { schedule_delayed_work(&tty->buf.work, 1); break; } if (count > tty->receive_room) count = tty->receive_room; char_buf = head->char_buf_ptr + head->read; flag_buf = head->flag_buf_ptr + head->read; head->read += count; spin_unlock_irqrestore(&tty->buf.lock, flags); disc->receive_buf(tty, char_buf, flag_buf, count); spin_lock_irqsave(&tty->buf.lock, flags); } tty->buf.head = head; } spin_unlock_irqrestore(&tty->buf.lock, flags); tty_ldisc_deref(disc); } /** * tty_flip_buffer_push - terminal * @tty: tty to push * * Queue a push of the terminal flip buffers to the line discipline. This * function must not be called from IRQ context if tty->low_latency is set. * * In the event of the queue being busy for flipping the work will be * held off and retried later. * * Locking: tty buffer lock. Driver locks in low latency mode. */ void tty_flip_buffer_push(struct tty_struct *tty) { unsigned long flags; spin_lock_irqsave(&tty->buf.lock, flags); if (tty->buf.tail != NULL) tty->buf.tail->commit = tty->buf.tail->used; spin_unlock_irqrestore(&tty->buf.lock, flags); if (tty->low_latency) flush_to_ldisc(&tty->buf.work.work); else schedule_delayed_work(&tty->buf.work, 1); } EXPORT_SYMBOL(tty_flip_buffer_push); /** * initialize_tty_struct * @tty: tty to initialize * * This subroutine initializes a tty structure that has been newly * allocated. * * Locking: none - tty in question must not be exposed at this point */ static void initialize_tty_struct(struct tty_struct *tty) { memset(tty, 0, sizeof(struct tty_struct)); tty->magic = TTY_MAGIC; tty_ldisc_assign(tty, tty_ldisc_get(N_TTY)); tty->pgrp = -1; tty->overrun_time = jiffies; tty->buf.head = tty->buf.tail = NULL; tty_buffer_init(tty); INIT_DELAYED_WORK(&tty->buf.work, flush_to_ldisc); init_MUTEX(&tty->buf.pty_sem); mutex_init(&tty->termios_mutex); init_waitqueue_head(&tty->write_wait); init_waitqueue_head(&tty->read_wait); INIT_WORK(&tty->hangup_work, do_tty_hangup); mutex_init(&tty->atomic_read_lock); mutex_init(&tty->atomic_write_lock); spin_lock_init(&tty->read_lock); INIT_LIST_HEAD(&tty->tty_files); INIT_WORK(&tty->SAK_work, NULL); } /* * The default put_char routine if the driver did not define one. */ static void tty_default_put_char(struct tty_struct *tty, unsigned char ch) { tty->driver->write(tty, &ch, 1); } static struct class *tty_class; /** * tty_register_device - register a tty device * @driver: the tty driver that describes the tty device * @index: the index in the tty driver for this tty device * @device: a struct device that is associated with this tty device. * This field is optional, if there is no known struct device * for this tty device it can be set to NULL safely. * * Returns a pointer to the struct device for this tty device * (or ERR_PTR(-EFOO) on error). * * This call is required to be made to register an individual tty device * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If * that bit is not set, this function should not be called by a tty * driver. * * Locking: ?? */ struct device *tty_register_device(struct tty_driver *driver, unsigned index, struct device *device) { char name[64]; dev_t dev = MKDEV(driver->major, driver->minor_start) + index; if (index >= driver->num) { printk(KERN_ERR "Attempt to register invalid tty line number " " (%d).\n", index); return ERR_PTR(-EINVAL); } if (driver->type == TTY_DRIVER_TYPE_PTY) pty_line_name(driver, index, name); else tty_line_name(driver, index, name); return device_create(tty_class, device, dev, name); } /** * tty_unregister_device - unregister a tty device * @driver: the tty driver that describes the tty device * @index: the index in the tty driver for this tty device * * If a tty device is registered with a call to tty_register_device() then * this function must be called when the tty device is gone. * * Locking: ?? */ void tty_unregister_device(struct tty_driver *driver, unsigned index) { device_destroy(tty_class, MKDEV(driver->major, driver->minor_start) + index); } EXPORT_SYMBOL(tty_register_device); EXPORT_SYMBOL(tty_unregister_device); struct tty_driver *alloc_tty_driver(int lines) { struct tty_driver *driver; driver = kmalloc(sizeof(struct tty_driver), GFP_KERNEL); if (driver) { memset(driver, 0, sizeof(struct tty_driver)); driver->magic = TTY_DRIVER_MAGIC; driver->num = lines; /* later we'll move allocation of tables here */ } return driver; } void put_tty_driver(struct tty_driver *driver) { kfree(driver); } void tty_set_operations(struct tty_driver *driver, const struct tty_operations *op) { driver->open = op->open; driver->close = op->close; driver->write = op->write; driver->put_char = op->put_char; driver->flush_chars = op->flush_chars; driver->write_room = op->write_room; driver->chars_in_buffer = op->chars_in_buffer; driver->ioctl = op->ioctl; driver->set_termios = op->set_termios; driver->throttle = op->throttle; driver->unthrottle = op->unthrottle; driver->stop = op->stop; driver->start = op->start; driver->hangup = op->hangup; driver->break_ctl = op->break_ctl; driver->flush_buffer = op->flush_buffer; driver->set_ldisc = op->set_ldisc; driver->wait_until_sent = op->wait_until_sent; driver->send_xchar = op->send_xchar; driver->read_proc = op->read_proc; driver->write_proc = op->write_proc; driver->tiocmget = op->tiocmget; driver->tiocmset = op->tiocmset; } EXPORT_SYMBOL(alloc_tty_driver); EXPORT_SYMBOL(put_tty_driver); EXPORT_SYMBOL(tty_set_operations); /* * Called by a tty driver to register itself. */ int tty_register_driver(struct tty_driver *driver) { int error; int i; dev_t dev; void **p = NULL; if (driver->flags & TTY_DRIVER_INSTALLED) return 0; if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM)) { p = kmalloc(driver->num * 3 * sizeof(void *), GFP_KERNEL); if (!p) return -ENOMEM; memset(p, 0, driver->num * 3 * sizeof(void *)); } if (!driver->major) { error = alloc_chrdev_region(&dev, driver->minor_start, driver->num, (char*)driver->name); if (!error) { driver->major = MAJOR(dev); driver->minor_start = MINOR(dev); } } else { dev = MKDEV(driver->major, driver->minor_start); error = register_chrdev_region(dev, driver->num, (char*)driver->name); } if (error < 0) { kfree(p); return error; } if (p) { driver->ttys = (struct tty_struct **)p; driver->termios = (struct ktermios **)(p + driver->num); driver->termios_locked = (struct ktermios **)(p + driver->num * 2); } else { driver->ttys = NULL; driver->termios = NULL; driver->termios_locked = NULL; } cdev_init(&driver->cdev, &tty_fops); driver->cdev.owner = driver->owner; error = cdev_add(&driver->cdev, dev, driver->num); if (error) { unregister_chrdev_region(dev, driver->num); driver->ttys = NULL; driver->termios = driver->termios_locked = NULL; kfree(p); return error; } if (!driver->put_char) driver->put_char = tty_default_put_char; list_add(&driver->tty_drivers, &tty_drivers); if ( !(driver->flags & TTY_DRIVER_DYNAMIC_DEV) ) { for(i = 0; i < driver->num; i++) tty_register_device(driver, i, NULL); } proc_tty_register_driver(driver); return 0; } EXPORT_SYMBOL(tty_register_driver); /* * Called by a tty driver to unregister itself. */ int tty_unregister_driver(struct tty_driver *driver) { int i; struct ktermios *tp; void *p; if (driver->refcount) return -EBUSY; unregister_chrdev_region(MKDEV(driver->major, driver->minor_start), driver->num); list_del(&driver->tty_drivers); /* * Free the termios and termios_locked structures because * we don't want to get memory leaks when modular tty * drivers are removed from the kernel. */ for (i = 0; i < driver->num; i++) { tp = driver->termios[i]; if (tp) { driver->termios[i] = NULL; kfree(tp); } tp = driver->termios_locked[i]; if (tp) { driver->termios_locked[i] = NULL; kfree(tp); } if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) tty_unregister_device(driver, i); } p = driver->ttys; proc_tty_unregister_driver(driver); driver->ttys = NULL; driver->termios = driver->termios_locked = NULL; kfree(p); cdev_del(&driver->cdev); return 0; } EXPORT_SYMBOL(tty_unregister_driver); dev_t tty_devnum(struct tty_struct *tty) { return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index; } EXPORT_SYMBOL(tty_devnum); void proc_clear_tty(struct task_struct *p) { spin_lock_irq(&p->sighand->siglock); p->signal->tty = NULL; spin_unlock_irq(&p->sighand->siglock); } EXPORT_SYMBOL(proc_clear_tty); void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty) { if (tty) { tty->session = process_session(tsk); tty->pgrp = process_group(tsk); } tsk->signal->tty = tty; tsk->signal->tty_old_pgrp = 0; } void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty) { spin_lock_irq(&tsk->sighand->siglock); __proc_set_tty(tsk, tty); spin_unlock_irq(&tsk->sighand->siglock); } struct tty_struct *get_current_tty(void) { struct tty_struct *tty; WARN_ON_ONCE(!mutex_is_locked(&tty_mutex)); tty = current->signal->tty; /* * session->tty can be changed/cleared from under us, make sure we * issue the load. The obtained pointer, when not NULL, is valid as * long as we hold tty_mutex. */ barrier(); return tty; } EXPORT_SYMBOL_GPL(get_current_tty); /* * Initialize the console device. This is called *early*, so * we can't necessarily depend on lots of kernel help here. * Just do some early initializations, and do the complex setup * later. */ void __init console_init(void) { initcall_t *call; /* Setup the default TTY line discipline. */ (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY); /* * set up the console device so that later boot sequences can * inform about problems etc.. */ #ifdef CONFIG_EARLY_PRINTK disable_early_printk(); #endif call = __con_initcall_start; while (call < __con_initcall_end) { (*call)(); call++; } } #ifdef CONFIG_VT extern int vty_init(void); #endif static int __init tty_class_init(void) { tty_class = class_create(THIS_MODULE, "tty"); if (IS_ERR(tty_class)) return PTR_ERR(tty_class); return 0; } postcore_initcall(tty_class_init); /* 3/2004 jmc: why do these devices exist? */ static struct cdev tty_cdev, console_cdev; #ifdef CONFIG_UNIX98_PTYS static struct cdev ptmx_cdev; #endif #ifdef CONFIG_VT static struct cdev vc0_cdev; #endif /* * Ok, now we can initialize the rest of the tty devices and can count * on memory allocations, interrupts etc.. */ static int __init tty_init(void) { cdev_init(&tty_cdev, &tty_fops); if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) || register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0) panic("Couldn't register /dev/tty driver\n"); device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), "tty"); cdev_init(&console_cdev, &console_fops); if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) || register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0) panic("Couldn't register /dev/console driver\n"); device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 1), "console"); #ifdef CONFIG_UNIX98_PTYS cdev_init(&ptmx_cdev, &ptmx_fops); if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) || register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0) panic("Couldn't register /dev/ptmx driver\n"); device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), "ptmx"); #endif #ifdef CONFIG_VT cdev_init(&vc0_cdev, &console_fops); if (cdev_add(&vc0_cdev, MKDEV(TTY_MAJOR, 0), 1) || register_chrdev_region(MKDEV(TTY_MAJOR, 0), 1, "/dev/vc/0") < 0) panic("Couldn't register /dev/tty0 driver\n"); device_create(tty_class, NULL, MKDEV(TTY_MAJOR, 0), "tty0"); vty_init(); #endif return 0; } module_init(tty_init);