From 88bb0de389a464521034e87816e5d6c7c489a664 Mon Sep 17 00:00:00 2001 From: Peter Hurley Date: Sat, 15 Jun 2013 09:14:16 -0400 Subject: [PATCH] n_tty: Factor canonical mode copy from n_tty_read() Simplify n_tty_read(); extract complex copy algorithm into separate function, canon_copy_to_user(). Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman --- drivers/tty/n_tty.c | 95 +++++++++++++++++++++++++++------------------ 1 file changed, 57 insertions(+), 38 deletions(-) diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index eddeb7889e62..7fd77746f2d0 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -1747,6 +1747,62 @@ static int copy_from_read_buf(struct tty_struct *tty, return retval; } +/** + * canon_copy_to_user - copy read data in canonical mode + * @tty: terminal device + * @b: user data + * @nr: size of data + * + * Helper function for n_tty_read. It is only called when ICANON is on; + * it copies characters one at a time from the read buffer to the user + * space buffer. + * + * Called under the atomic_read_lock mutex + */ + +static int canon_copy_to_user(struct tty_struct *tty, + unsigned char __user **b, + size_t *nr) +{ + struct n_tty_data *ldata = tty->disc_data; + unsigned long flags; + int eol, c; + + /* N.B. avoid overrun if nr == 0 */ + raw_spin_lock_irqsave(&ldata->read_lock, flags); + while (*nr && ldata->read_cnt) { + + eol = test_and_clear_bit(ldata->read_tail, ldata->read_flags); + c = ldata->read_buf[ldata->read_tail]; + ldata->read_tail = (ldata->read_tail+1) & (N_TTY_BUF_SIZE-1); + ldata->read_cnt--; + if (eol) { + /* this test should be redundant: + * we shouldn't be reading data if + * canon_data is 0 + */ + if (--ldata->canon_data < 0) + ldata->canon_data = 0; + } + raw_spin_unlock_irqrestore(&ldata->read_lock, flags); + + if (!eol || (c != __DISABLED_CHAR)) { + if (tty_put_user(tty, c, *b)) + return -EFAULT; + *b += 1; + *nr -= 1; + } + if (eol) { + tty_audit_push(tty); + return 0; + } + raw_spin_lock_irqsave(&ldata->read_lock, flags); + } + raw_spin_unlock_irqrestore(&ldata->read_lock, flags); + + return 0; +} + extern ssize_t redirected_tty_write(struct file *, const char __user *, size_t, loff_t *); @@ -1916,44 +1972,7 @@ do_it_again: } if (ldata->icanon && !L_EXTPROC(tty)) { - /* N.B. avoid overrun if nr == 0 */ - raw_spin_lock_irqsave(&ldata->read_lock, flags); - while (nr && ldata->read_cnt) { - int eol; - - eol = test_and_clear_bit(ldata->read_tail, - ldata->read_flags); - c = ldata->read_buf[ldata->read_tail]; - ldata->read_tail = ((ldata->read_tail+1) & - (N_TTY_BUF_SIZE-1)); - ldata->read_cnt--; - if (eol) { - /* this test should be redundant: - * we shouldn't be reading data if - * canon_data is 0 - */ - if (--ldata->canon_data < 0) - ldata->canon_data = 0; - } - raw_spin_unlock_irqrestore(&ldata->read_lock, flags); - - if (!eol || (c != __DISABLED_CHAR)) { - if (tty_put_user(tty, c, b++)) { - retval = -EFAULT; - b--; - raw_spin_lock_irqsave(&ldata->read_lock, flags); - break; - } - nr--; - } - if (eol) { - tty_audit_push(tty); - raw_spin_lock_irqsave(&ldata->read_lock, flags); - break; - } - raw_spin_lock_irqsave(&ldata->read_lock, flags); - } - raw_spin_unlock_irqrestore(&ldata->read_lock, flags); + retval = canon_copy_to_user(tty, &b, &nr); if (retval) break; } else { -- 2.20.1