From f6c8dbe6e50c6e5121d7b6644718207daa008221 Mon Sep 17 00:00:00 2001 From: Peter Hurley Date: Sat, 15 Jun 2013 07:28:28 -0400 Subject: [PATCH] n_tty: Encapsulate minimum_to_wake within N_TTY minimum_to_wake is unique to N_TTY processing, and belongs in per-ldisc data. Add the ldisc method, ldisc_ops::fasync(), to notify line disciplines when signal-driven I/O is enabled or disabled. When enabled for N_TTY (by fcntl(F_SETFL, O_ASYNC)), blocking reader/polls will be woken for any readable input. When disabled, blocking reader/polls are not woken until the read buffer is full. Canonical mode (L_ICANON(tty), n_tty_data::icanon) is not affected by the minimum_to_wake setting. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman --- drivers/tty/n_tty.c | 39 +++++++++++++++++++++++++++------------ drivers/tty/tty_io.c | 17 +++++++++-------- include/linux/tty.h | 1 - include/linux/tty_ldisc.h | 6 ++++++ 4 files changed, 42 insertions(+), 21 deletions(-) diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index cdcdb0ea061a..f1806de69b18 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -89,6 +89,7 @@ struct n_tty_data { int read_head; int read_tail; int read_cnt; + int minimum_to_wake; unsigned char *echo_buf; unsigned int echo_pos; @@ -1455,7 +1456,7 @@ static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp, n_tty_set_room(tty); - if ((!ldata->icanon && (ldata->read_cnt >= tty->minimum_to_wake)) || + if ((!ldata->icanon && (ldata->read_cnt >= ldata->minimum_to_wake)) || L_EXTPROC(tty)) { kill_fasync(&tty->fasync, SIGIO, POLL_IN); if (waitqueue_active(&tty->read_wait)) @@ -1636,7 +1637,7 @@ static int n_tty_open(struct tty_struct *tty) tty->disc_data = ldata; reset_buffer_flags(tty->disc_data); ldata->column = 0; - tty->minimum_to_wake = 1; + ldata->minimum_to_wake = 1; tty->closing = 0; /* indicate buffer work may resume */ clear_bit(TTY_LDISC_HALTED, &tty->flags); @@ -1804,17 +1805,17 @@ do_it_again: minimum = MIN_CHAR(tty); if (minimum) { if (time) - tty->minimum_to_wake = 1; + ldata->minimum_to_wake = 1; else if (!waitqueue_active(&tty->read_wait) || - (tty->minimum_to_wake > minimum)) - tty->minimum_to_wake = minimum; + (ldata->minimum_to_wake > minimum)) + ldata->minimum_to_wake = minimum; } else { timeout = 0; if (time) { timeout = time; time = 0; } - tty->minimum_to_wake = minimum = 1; + ldata->minimum_to_wake = minimum = 1; } } @@ -1854,9 +1855,9 @@ do_it_again: TASK_RUNNING. */ set_current_state(TASK_INTERRUPTIBLE); - if (((minimum - (b - buf)) < tty->minimum_to_wake) && + if (((minimum - (b - buf)) < ldata->minimum_to_wake) && ((minimum - (b - buf)) >= 1)) - tty->minimum_to_wake = (minimum - (b - buf)); + ldata->minimum_to_wake = (minimum - (b - buf)); if (!input_available_p(tty, 0)) { if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) { @@ -1973,7 +1974,7 @@ do_it_again: remove_wait_queue(&tty->read_wait, &wait); if (!waitqueue_active(&tty->read_wait)) - tty->minimum_to_wake = minimum; + ldata->minimum_to_wake = minimum; __set_current_state(TASK_RUNNING); size = b - buf; @@ -2105,6 +2106,7 @@ break_out: static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file, poll_table *wait) { + struct n_tty_data *ldata = tty->disc_data; unsigned int mask = 0; poll_wait(file, &tty->read_wait, wait); @@ -2119,9 +2121,9 @@ static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file, mask |= POLLHUP; if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) { if (MIN_CHAR(tty) && !TIME_CHAR(tty)) - tty->minimum_to_wake = MIN_CHAR(tty); + ldata->minimum_to_wake = MIN_CHAR(tty); else - tty->minimum_to_wake = 1; + ldata->minimum_to_wake = 1; } if (tty->ops->write && !tty_is_writelocked(tty) && tty_chars_in_buffer(tty) < WAKEUP_CHARS && @@ -2169,6 +2171,18 @@ static int n_tty_ioctl(struct tty_struct *tty, struct file *file, } } +static void n_tty_fasync(struct tty_struct *tty, int on) +{ + struct n_tty_data *ldata = tty->disc_data; + + if (!waitqueue_active(&tty->read_wait)) { + if (on) + ldata->minimum_to_wake = 1; + else if (!tty->fasync) + ldata->minimum_to_wake = N_TTY_BUF_SIZE; + } +} + struct tty_ldisc_ops tty_ldisc_N_TTY = { .magic = TTY_LDISC_MAGIC, .name = "n_tty", @@ -2182,7 +2196,8 @@ struct tty_ldisc_ops tty_ldisc_N_TTY = { .set_termios = n_tty_set_termios, .poll = n_tty_poll, .receive_buf = n_tty_receive_buf, - .write_wakeup = n_tty_write_wakeup + .write_wakeup = n_tty_write_wakeup, + .fasync = n_tty_fasync, }; /** diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index 6464029e4860..bd88007fa6ea 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -2138,6 +2138,7 @@ static unsigned int tty_poll(struct file *filp, poll_table *wait) static int __tty_fasync(int fd, struct file *filp, int on) { struct tty_struct *tty = file_tty(filp); + struct tty_ldisc *ldisc; unsigned long flags; int retval = 0; @@ -2148,11 +2149,17 @@ static int __tty_fasync(int fd, struct file *filp, int on) if (retval <= 0) goto out; + ldisc = tty_ldisc_ref(tty); + if (ldisc) { + if (ldisc->ops->fasync) + ldisc->ops->fasync(tty, on); + tty_ldisc_deref(ldisc); + } + if (on) { enum pid_type type; struct pid *pid; - if (!waitqueue_active(&tty->read_wait)) - tty->minimum_to_wake = 1; + spin_lock_irqsave(&tty->ctrl_lock, flags); if (tty->pgrp) { pid = tty->pgrp; @@ -2165,13 +2172,7 @@ static int __tty_fasync(int fd, struct file *filp, int on) spin_unlock_irqrestore(&tty->ctrl_lock, flags); retval = __f_setown(filp, pid, type, 0); put_pid(pid); - if (retval) - goto out; - } else { - if (!tty->fasync && !waitqueue_active(&tty->read_wait)) - tty->minimum_to_wake = N_TTY_BUF_SIZE; } - retval = 0; out: return retval; } diff --git a/include/linux/tty.h b/include/linux/tty.h index 82ab69bc9b79..01ac30efd6a6 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -272,7 +272,6 @@ struct tty_struct { #define N_TTY_BUF_SIZE 4096 unsigned char closing:1; - unsigned short minimum_to_wake; unsigned char *write_buf; int write_cnt; /* If the tty has a pending do_SAK, queue it here - akpm */ diff --git a/include/linux/tty_ldisc.h b/include/linux/tty_ldisc.h index 7b24bbd85ea8..a1b048999821 100644 --- a/include/linux/tty_ldisc.h +++ b/include/linux/tty_ldisc.h @@ -100,6 +100,11 @@ * seek to perform this action quickly but should wait until * any pending driver I/O is completed. * + * void (*fasync)(struct tty_struct *, int on) + * + * Notify line discipline when signal-driven I/O is enabled or + * disabled. + * * void (*dcd_change)(struct tty_struct *tty, unsigned int status) * * Tells the discipline that the DCD pin has changed its status. @@ -189,6 +194,7 @@ struct tty_ldisc_ops { char *fp, int count); void (*write_wakeup)(struct tty_struct *); void (*dcd_change)(struct tty_struct *, unsigned int); + void (*fasync)(struct tty_struct *tty, int on); struct module *owner; -- 2.39.5