diff options
Diffstat (limited to 'drivers/char/n_tty.c')
| -rw-r--r-- | drivers/char/n_tty.c | 125 |
1 files changed, 100 insertions, 25 deletions
diff --git a/drivers/char/n_tty.c b/drivers/char/n_tty.c index 708c2b1dbe51..efbfe9612658 100644 --- a/drivers/char/n_tty.c +++ b/drivers/char/n_tty.c @@ -26,7 +26,7 @@ * * 2002/03/18 Implemented n_tty_wakeup to send SIGIO POLL_OUTs to * waiting writing processes-Sapan Bhatia <sapan@corewars.org>. - * Also fixed a bug in BLOCKING mode where write_chan returns + * Also fixed a bug in BLOCKING mode where n_tty_write returns * EAGAIN */ @@ -99,6 +99,7 @@ static inline int tty_put_user(struct tty_struct *tty, unsigned char x, static void n_tty_set_room(struct tty_struct *tty) { + /* tty->read_cnt is not read locked ? */ int left = N_TTY_BUF_SIZE - tty->read_cnt - 1; /* @@ -121,6 +122,16 @@ static void put_tty_queue_nolock(unsigned char c, struct tty_struct *tty) } } +/** + * put_tty_queue - add character to tty + * @c: character + * @tty: tty device + * + * Add a character to the tty read_buf queue. This is done under the + * read_lock to serialize character addition and also to protect us + * against parallel reads or flushes + */ + static void put_tty_queue(unsigned char c, struct tty_struct *tty) { unsigned long flags; @@ -137,14 +148,11 @@ static void put_tty_queue(unsigned char c, struct tty_struct *tty) * check_unthrottle - allow new receive data * @tty; tty device * - * Check whether to call the driver.unthrottle function. - * We test the TTY_THROTTLED bit first so that it always - * indicates the current state. The decision about whether - * it is worth allowing more input has been taken by the caller. + * Check whether to call the driver unthrottle functions + * * Can sleep, may be called under the atomic_read_lock mutex but * this is not guaranteed. */ - static void check_unthrottle(struct tty_struct *tty) { if (tty->count) @@ -158,6 +166,8 @@ static void check_unthrottle(struct tty_struct *tty) * Reset the read buffer counters, clear the flags, * and make sure the driver is unthrottled. Called * from n_tty_open() and n_tty_flush_buffer(). + * + * Locking: tty_read_lock for read fields. */ static void reset_buffer_flags(struct tty_struct *tty) { @@ -181,7 +191,7 @@ static void reset_buffer_flags(struct tty_struct *tty) * at hangup) or when the N_TTY line discipline internally has to * clean the pending queue (for example some signals). * - * Locking: ctrl_lock + * Locking: ctrl_lock, read_lock. */ static void n_tty_flush_buffer(struct tty_struct *tty) @@ -207,6 +217,8 @@ static void n_tty_flush_buffer(struct tty_struct *tty) * * Report the number of characters buffered to be delivered to user * at this instant in time. + * + * Locking: read_lock */ static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty) @@ -346,7 +358,7 @@ static int opost(unsigned char c, struct tty_struct *tty) * the simple cases normally found and helps to generate blocks of * symbols for the console driver and thus improve performance. * - * Called from write_chan under the tty layer write lock. Relies + * Called from n_tty_write under the tty layer write lock. Relies * on lock_kernel for the tty->column state. */ @@ -410,6 +422,8 @@ break_out: * * Echo user input back onto the screen. This must be called only when * L_ECHO(tty) is true. Called from the driver receive_buf path. + * + * Relies on BKL for tty column locking */ static void echo_char(unsigned char c, struct tty_struct *tty) @@ -422,6 +436,12 @@ static void echo_char(unsigned char c, struct tty_struct *tty) opost(c, tty); } +/** + * finsh_erasing - complete erase + * @tty: tty doing the erase + * + * Relies on BKL for tty column locking + */ static inline void finish_erasing(struct tty_struct *tty) { if (tty->erasing) { @@ -439,6 +459,8 @@ static inline void finish_erasing(struct tty_struct *tty) * Perform erase and necessary output when an erase character is * present in the stream from the driver layer. Handles the complexities * of UTF-8 multibyte symbols. + * + * Locking: read_lock for tty buffers, BKL for column/erasing state */ static void eraser(unsigned char c, struct tty_struct *tty) @@ -447,6 +469,7 @@ static void eraser(unsigned char c, struct tty_struct *tty) int head, seen_alnums, cnt; unsigned long flags; + /* FIXME: locking needed ? */ if (tty->read_head == tty->canon_head) { /* opost('\a', tty); */ /* what do you think? */ return; @@ -481,6 +504,7 @@ static void eraser(unsigned char c, struct tty_struct *tty) } seen_alnums = 0; + /* FIXME: Locking ?? */ while (tty->read_head != tty->canon_head) { head = tty->read_head; @@ -583,6 +607,8 @@ static void eraser(unsigned char c, struct tty_struct *tty) * may caus terminal flushing to take place according to the termios * settings and character used. Called from the driver receive_buf * path so serialized. + * + * Locking: ctrl_lock, read_lock (both via flush buffer) */ static inline void isig(int sig, struct tty_struct *tty, int flush) @@ -1007,12 +1033,26 @@ int is_ignored(int sig) * and is protected from re-entry by the tty layer. The user is * guaranteed that this function will not be re-entered or in progress * when the ldisc is closed. + * + * Locking: Caller holds tty->termios_mutex */ static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old) { - if (!tty) - return; + int canon_change = 1; + BUG_ON(!tty); + + if (old) + canon_change = (old->c_lflag ^ tty->termios->c_lflag) & ICANON; + if (canon_change) { + memset(&tty->read_flags, 0, sizeof tty->read_flags); + tty->canon_head = tty->read_tail; + tty->canon_data = 0; + tty->erasing = 0; + } + + if (canon_change && !L_ICANON(tty) && tty->read_cnt) + wake_up_interruptible(&tty->read_wait); tty->icanon = (L_ICANON(tty) != 0); if (test_bit(TTY_HW_COOK_IN, &tty->flags)) { @@ -1143,7 +1183,7 @@ static inline int input_available_p(struct tty_struct *tty, int amt) * @b: user data * @nr: size of data * - * Helper function to speed up read_chan. It is only called when + * Helper function to speed up n_tty_read. It is only called when * ICANON is off; it copies characters straight from the tty queue to * user space directly. It can be profitably called twice; once to * drain the space from the tail pointer to the (physical) end of the @@ -1210,7 +1250,7 @@ static int job_control(struct tty_struct *tty, struct file *file) if (file->f_op->write != redirected_tty_write && current->signal->tty == tty) { if (!tty->pgrp) - printk(KERN_ERR "read_chan: no tty->pgrp!\n"); + printk(KERN_ERR "n_tty_read: no tty->pgrp!\n"); else if (task_pgrp(current) != tty->pgrp) { if (is_ignored(SIGTTIN) || is_current_pgrp_orphaned()) @@ -1225,7 +1265,7 @@ static int job_control(struct tty_struct *tty, struct file *file) /** - * read_chan - read function for tty + * n_tty_read - read function for tty * @tty: tty device * @file: file object * @buf: userspace buffer pointer @@ -1239,7 +1279,7 @@ static int job_control(struct tty_struct *tty, struct file *file) * This code must be sure never to sleep through a hangup. */ -static ssize_t read_chan(struct tty_struct *tty, struct file *file, +static ssize_t n_tty_read(struct tty_struct *tty, struct file *file, unsigned char __user *buf, size_t nr) { unsigned char __user *b = buf; @@ -1254,10 +1294,7 @@ static ssize_t read_chan(struct tty_struct *tty, struct file *file, do_it_again: - if (!tty->read_buf) { - printk(KERN_ERR "n_tty_read_chan: read_buf == NULL?!?\n"); - return -EIO; - } + BUG_ON(!tty->read_buf); c = job_control(tty, file); if (c < 0) @@ -1444,7 +1481,7 @@ do_it_again: } /** - * write_chan - write function for tty + * n_tty_write - write function for tty * @tty: tty device * @file: file object * @buf: userspace buffer pointer @@ -1458,7 +1495,7 @@ do_it_again: * This code must be sure never to sleep through a hangup. */ -static ssize_t write_chan(struct tty_struct *tty, struct file *file, +static ssize_t n_tty_write(struct tty_struct *tty, struct file *file, const unsigned char *buf, size_t nr) { const unsigned char *b = buf; @@ -1532,7 +1569,7 @@ break_out: } /** - * normal_poll - poll method for N_TTY + * n_tty_poll - poll method for N_TTY * @tty: terminal device * @file: file accessing it * @wait: poll table @@ -1545,7 +1582,7 @@ break_out: * Called without the kernel lock held - fine */ -static unsigned int normal_poll(struct tty_struct *tty, struct file *file, +static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file, poll_table *wait) { unsigned int mask = 0; @@ -1573,6 +1610,44 @@ static unsigned int normal_poll(struct tty_struct *tty, struct file *file, return mask; } +static unsigned long inq_canon(struct tty_struct *tty) +{ + int nr, head, tail; + + if (!tty->canon_data) + return 0; + head = tty->canon_head; + tail = tty->read_tail; + nr = (head - tail) & (N_TTY_BUF_SIZE-1); + /* Skip EOF-chars.. */ + while (head != tail) { + if (test_bit(tail, tty->read_flags) && + tty->read_buf[tail] == __DISABLED_CHAR) + nr--; + tail = (tail+1) & (N_TTY_BUF_SIZE-1); + } + return nr; +} + +static int n_tty_ioctl(struct tty_struct *tty, struct file *file, + unsigned int cmd, unsigned long arg) +{ + int retval; + + switch (cmd) { + case TIOCOUTQ: + return put_user(tty_chars_in_buffer(tty), (int __user *) arg); + case TIOCINQ: + /* FIXME: Locking */ + retval = tty->read_cnt; + if (L_ICANON(tty)) + retval = inq_canon(tty); + return put_user(retval, (unsigned int __user *) arg); + default: + return n_tty_ioctl_helper(tty, file, cmd, arg); + } +} + struct tty_ldisc_ops tty_ldisc_N_TTY = { .magic = TTY_LDISC_MAGIC, .name = "n_tty", @@ -1580,11 +1655,11 @@ struct tty_ldisc_ops tty_ldisc_N_TTY = { .close = n_tty_close, .flush_buffer = n_tty_flush_buffer, .chars_in_buffer = n_tty_chars_in_buffer, - .read = read_chan, - .write = write_chan, + .read = n_tty_read, + .write = n_tty_write, .ioctl = n_tty_ioctl, .set_termios = n_tty_set_termios, - .poll = normal_poll, + .poll = n_tty_poll, .receive_buf = n_tty_receive_buf, .write_wakeup = n_tty_write_wakeup }; |