diff options
Diffstat (limited to 'drivers/char/tty_io.c')
| -rw-r--r-- | drivers/char/tty_io.c | 808 |
1 files changed, 737 insertions, 71 deletions
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c index bfdb90242a9..bb0d9199e99 100644 --- a/drivers/char/tty_io.c +++ b/drivers/char/tty_io.c @@ -153,6 +153,15 @@ int tty_ioctl(struct inode * inode, struct file * file, 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 + * FIXME: use kzalloc + */ static struct tty_struct *alloc_tty_struct(void) { @@ -166,6 +175,15 @@ static struct tty_struct *alloc_tty_struct(void) 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); @@ -175,6 +193,17 @@ static inline void free_tty_struct(struct tty_struct *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. */ @@ -235,6 +264,28 @@ static int check_tty_count(struct tty_struct *tty, const char *routine) * 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 + */ + + +/** + * 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; @@ -247,19 +298,47 @@ static void tty_buffer_free_all(struct tty_struct *tty) 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; } -static struct tty_buffer *tty_buffer_alloc(size_t size) +/** + * 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 = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC); + 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; @@ -269,17 +348,27 @@ static struct tty_buffer *tty_buffer_alloc(size_t size) p->read = 0; p->char_buf_ptr = (char *)(p->data); p->flag_buf_ptr = (unsigned char *)p->char_buf_ptr + size; -/* printk("Flip create %p\n", p); */ + tty->buf.memory_used += size; return p; } -/* Must be called with the tty_read lock held. This needs to acquire strategy - code to decide if we should kfree or relink a given expired buffer */ +/** + * 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 */ -/* printk("Flip dispose %p\n", b); */ + tty->buf.memory_used -= b->size; + WARN_ON(tty->buf.memory_used < 0); + if(b->size >= 512) kfree(b); else { @@ -288,6 +377,18 @@ static void tty_buffer_free(struct tty_struct *tty, struct tty_buffer *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; @@ -299,20 +400,28 @@ static struct tty_buffer *tty_buffer_find(struct tty_struct *tty, size_t size) t->used = 0; t->commit = 0; t->read = 0; - /* DEBUG ONLY */ -/* memset(t->data, '*', size); */ -/* printk("Flip recycle %p\n", t); */ + tty->buf.memory_used += t->size; return t; } tbh = &((*tbh)->next); } /* Round the buffer size out */ size = (size + 0xFF) & ~ 0xFF; - return tty_buffer_alloc(size); + 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; @@ -347,6 +456,18 @@ int tty_buffer_request_room(struct tty_struct *tty, size_t 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) { @@ -370,6 +491,20 @@ int tty_insert_flip_string(struct tty_struct *tty, const unsigned char *chars, } 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) { @@ -394,6 +529,17 @@ int tty_insert_flip_string_flags(struct tty_struct *tty, } 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; @@ -405,12 +551,19 @@ void tty_schedule_flip(struct tty_struct *tty) } 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) @@ -427,12 +580,20 @@ int tty_prepare_flip_string(struct tty_struct *tty, unsigned char **chars, size_ 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) @@ -451,10 +612,16 @@ 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_sem */ static void tty_set_termios_ldisc(struct tty_struct *tty, int num) @@ -474,6 +641,19 @@ 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; @@ -493,6 +673,18 @@ int tty_register_ldisc(int disc, struct tty_ldisc *new_ldisc) } 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; @@ -512,6 +704,19 @@ int tty_unregister_ldisc(int disc) } 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; @@ -540,6 +745,17 @@ struct tty_ldisc *tty_ldisc_get(int disc) 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; @@ -557,6 +773,19 @@ void tty_ldisc_put(int disc) 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; @@ -571,6 +800,8 @@ static void tty_ldisc_assign(struct tty_struct *tty, struct tty_ldisc *ld) * 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) @@ -602,6 +833,8 @@ static int tty_ldisc_try(struct tty_struct *tty) * 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) @@ -622,6 +855,8 @@ EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait); * 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) @@ -639,6 +874,8 @@ EXPORT_SYMBOL_GPL(tty_ldisc_ref); * * 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) @@ -683,6 +920,9 @@ static void tty_ldisc_enable(struct tty_struct *tty) * * Set the discipline of a tty line. Must be called from a process * context. + * + * Locking: takes tty_ldisc_lock. + * called functions take termios_sem */ static int tty_set_ldisc(struct tty_struct *tty, int ldisc) @@ -846,9 +1086,17 @@ restart: return retval; } -/* - * This routine returns a tty driver structure, given a device number +/** + * 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; @@ -863,11 +1111,17 @@ static struct tty_driver *get_tty_driver(dev_t device, int *index) return NULL; } -/* - * 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) +/** + * 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) @@ -1005,10 +1259,27 @@ void tty_ldisc_flush(struct tty_struct *tty) EXPORT_SYMBOL_GPL(tty_ldisc_flush); -/* - * 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.. +/** + * do_tty_hangup - actual handler for hangup events + * @data: 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_sem resetting termios data + * tasklist_lock to walk task list for hangup event + * */ static void do_tty_hangup(void *data) { @@ -1133,6 +1404,14 @@ static void do_tty_hangup(void *data) 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 @@ -1145,6 +1424,15 @@ void tty_hangup(struct tty_struct * tty) 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 @@ -1156,6 +1444,14 @@ void tty_vhangup(struct tty_struct * tty) } 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); @@ -1163,19 +1459,28 @@ int tty_hung_up_p(struct file * filp) EXPORT_SYMBOL(tty_hung_up_p); -/* - * This function is typically called only by the session leader, when - * it wants to disassociate itself from its controlling tty. +/** + * 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: + * 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. + * 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: tty_mutex is taken to protect current->signal->tty + * BKL is taken for hysterical raisins + * Tasklist lock is taken (under tty_mutex) to walk process + * lists for the session. */ + void disassociate_ctty(int on_exit) { struct tty_struct *tty; @@ -1222,6 +1527,25 @@ void disassociate_ctty(int on_exit) 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) @@ -1238,6 +1562,19 @@ void stop_tty(struct tty_struct *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) @@ -1258,6 +1595,23 @@ void start_tty(struct tty_struct *tty) 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) { @@ -1302,6 +1656,7 @@ static inline ssize_t do_tty_write( ssize_t ret = 0, written = 0; unsigned int chunk; + /* FIXME: O_NDELAY ... */ if (mutex_lock_interruptible(&tty->atomic_write_lock)) { return -ERESTARTSYS; } @@ -1318,6 +1673,9 @@ static inline ssize_t do_tty_write( * 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)) @@ -1375,6 +1733,24 @@ static inline ssize_t do_tty_write( } +/** + * 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) { @@ -1422,7 +1798,18 @@ ssize_t redirected_tty_write(struct file * file, const char __user * buf, size_t static char ptychar[] = "pqrstuvwxyzabcde"; -static inline void pty_line_name(struct tty_driver *driver, int index, char *p) +/** + * 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 */ @@ -1431,24 +1818,53 @@ static inline void pty_line_name(struct tty_driver *driver, int index, char *p) ptychar[i >> 4 & 0xf], i & 0xf); } -static inline void tty_line_name(struct tty_driver *driver, int index, char *p) +/** + * 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 termios *tp, **tp_loc, *o_tp, **o_tp_loc; struct termios *ltp, **ltp_loc, *o_ltp, **o_ltp_loc; - int retval=0; + int retval = 0; /* check whether we're reopening an existing tty */ if (driver->flags & TTY_DRIVER_DEVPTS_MEM) { @@ -1662,10 +2078,20 @@ release_mem_out: goto end_init; } -/* - * Releases memory associated with a tty structure, and clears out the - * driver table slots. +/** + * 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; @@ -2006,18 +2432,27 @@ static void release_dev(struct file * filp) } -/* - * 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. +/** + * 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) + * 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. + * The termios state of a pty is reset on first open so that + * settings don't persist across reuse. + * + * Locking: tty_mutex protects current->signal->tty, get_tty_driver and + * init_dev work. tty->count should protect the rest. + * task_lock is held to update task details for sessions */ + static int tty_open(struct inode * inode, struct file * filp) { struct tty_struct *tty; @@ -2132,6 +2567,18 @@ got_driver: } #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; @@ -2191,6 +2638,18 @@ out: } #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(); @@ -2199,7 +2658,18 @@ static int tty_release(struct inode * inode, struct file * filp) return 0; } -/* No kernel lock held - fine */ +/** + * 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; @@ -2243,6 +2713,21 @@ static int tty_fasync(int fd, struct file * filp, int on) 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 + */ + static int tiocsti(struct tty_struct *tty, char __user *p) { char ch, mbz = 0; @@ -2258,6 +2743,18 @@ static int tiocsti(struct tty_struct *tty, char __user *p) 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. No + * locking is done. + * + * FIXME: Returning random values racing a window size set is wrong + * should lock here against that + */ + static int tiocgwinsz(struct tty_struct *tty, struct winsize __user * arg) { if (copy_to_user(arg, &tty->winsize, sizeof(*arg))) @@ -2265,6 +2762,24 @@ static int tiocgwinsz(struct tty_struct *tty, struct winsize __user * arg) return 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: + * The console_sem is used to ensure we do not try and resize + * the console twice at once. + * FIXME: Two racing size sets may leave the console and kernel + * parameters disagreeing. Is this exploitable ? + * FIXME: Random values racing a window size get is wrong + * should lock here against that + */ + static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty, struct winsize __user * arg) { @@ -2294,6 +2809,15 @@ static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty, 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)) @@ -2319,6 +2843,17 @@ static int tioccons(struct file *file) 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) { @@ -2334,6 +2869,23 @@ static int fionbio(struct file *file, int __user *p) 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 tasklist lock internally to walk sessions + * Takes task_lock() when updating signal->tty + * + * FIXME: tty_mutex is needed to protect signal->tty references. + * FIXME: why task_lock on the signal->tty reference ?? + * + */ + static int tiocsctty(struct tty_struct *tty, int arg) { struct task_struct *p; @@ -2374,6 +2926,18 @@ static int tiocsctty(struct tty_struct *tty, int arg) return 0; } +/** + * 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 ->signal->tty is safe. + */ + static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p) { /* @@ -2385,6 +2949,20 @@ static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t 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 + * + * FIXME: current->signal->tty referencing is unsafe. + */ + static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p) { pid_t pgrp; @@ -2408,6 +2986,18 @@ static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t 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 ->signal->tty is safe. + */ + static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p) { /* @@ -2421,6 +3011,16 @@ static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t _ 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; @@ -2430,6 +3030,21 @@ static int tiocsetd(struct tty_struct *tty, int __user *p) 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: + * None + * + * FIXME: + * What if two overlap + */ + static int send_break(struct tty_struct *tty, unsigned int duration) { tty->driver->break_ctl(tty, -1); @@ -2442,8 +3057,19 @@ static int send_break(struct tty_struct *tty, unsigned int duration) return 0; } -static int -tty_tiocmget(struct tty_struct *tty, struct file *file, int __user *p) +/** + * 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; @@ -2456,8 +3082,20 @@ tty_tiocmget(struct tty_struct *tty, struct file *file, int __user *p) return retval; } -static int -tty_tiocmset(struct tty_struct *tty, struct file *file, unsigned int cmd, +/** + * 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; @@ -2573,6 +3211,7 @@ int tty_ioctl(struct inode * inode, struct file * file, clear_bit(TTY_EXCLUSIVE, &tty->flags); return 0; case TIOCNOTTY: + /* FIXME: taks lock or tty_mutex ? */ if (current->signal->tty != tty) return -ENOTTY; if (current->signal->leader) @@ -2753,9 +3392,16 @@ void do_SAK(struct tty_struct *tty) EXPORT_SYMBOL(do_SAK); -/* - * This routine is called out of the software interrupt to flush data - * from the buffer chain to the line discipline. +/** + * flush_to_ldisc + * @private_: 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(void *private_) @@ -2831,6 +3477,8 @@ static int n_baud_table = ARRAY_SIZE(baud_table); * Convert termios baud rate data into a speed. This should be called * with the termios lock held if this termios is a terminal termios * structure. May change the termios data. + * + * Locking: none */ int tty_termios_baud_rate(struct termios *termios) @@ -2859,6 +3507,8 @@ EXPORT_SYMBOL(tty_termios_baud_rate); * Returns the baud rate as an integer for this terminal. The * termios lock must be held by the caller and the terminal bit * flags may be updated. + * + * Locking: none */ int tty_get_baud_rate(struct tty_struct *tty) @@ -2888,6 +3538,8 @@ EXPORT_SYMBOL(tty_get_baud_rate); * * 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) @@ -2907,9 +3559,16 @@ void tty_flip_buffer_push(struct tty_struct *tty) EXPORT_SYMBOL(tty_flip_buffer_push); -/* - * This subroutine initializes a tty structure. +/** + * 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)); @@ -2935,6 +3594,7 @@ static void initialize_tty_struct(struct tty_struct *tty) /* * 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); @@ -2943,19 +3603,23 @@ static void tty_default_put_char(struct tty_struct *tty, unsigned char ch) 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. + * 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 class device (or ERR_PTR(-EFOO) on error). + * Returns a pointer to the class 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. + * 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 class_device *tty_register_device(struct tty_driver *driver, unsigned index, struct device *device) { @@ -2977,13 +3641,16 @@ struct class_device *tty_register_device(struct tty_driver *driver, } /** - * 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 + * 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 made when the tty device is gone. + * 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) { class_device_destroy(tty_class, MKDEV(driver->major, driver->minor_start) + index); @@ -3094,7 +3761,6 @@ int tty_register_driver(struct tty_driver *driver) driver->cdev.owner = driver->owner; error = cdev_add(&driver->cdev, dev, driver->num); if (error) { - cdev_del(&driver->cdev); unregister_chrdev_region(dev, driver->num); driver->ttys = NULL; driver->termios = driver->termios_locked = NULL; |