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tty: Add diagnostic for halted line discipline
Flip buffer work must not be scheduled by the line discipline after the line discipline has been halted; issue warning. Note: drivers can still schedule flip buffer work. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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parent
91debb0383
commit
21622939fc
3 changed files with 15 additions and 1 deletions
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@ -153,6 +153,12 @@ static void n_tty_set_room(struct tty_struct *tty)
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if (left && !old_left) {
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if (left && !old_left) {
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WARN_RATELIMIT(tty->port->itty == NULL,
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WARN_RATELIMIT(tty->port->itty == NULL,
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"scheduling with invalid itty\n");
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"scheduling with invalid itty\n");
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/* see if ldisc has been killed - if so, this means that
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* even though the ldisc has been halted and ->buf.work
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* cancelled, ->buf.work is about to be rescheduled
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*/
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WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED, &tty->flags),
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"scheduling buffer work for halted ldisc\n");
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schedule_work(&tty->port->buf.work);
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schedule_work(&tty->port->buf.work);
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}
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}
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}
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}
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@ -1624,6 +1630,8 @@ static int n_tty_open(struct tty_struct *tty)
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goto err_free_bufs;
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goto err_free_bufs;
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tty->disc_data = ldata;
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tty->disc_data = ldata;
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/* indicate buffer work may resume */
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clear_bit(TTY_LDISC_HALTED, &tty->flags);
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reset_buffer_flags(tty);
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reset_buffer_flags(tty);
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tty_unthrottle(tty);
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tty_unthrottle(tty);
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ldata->column = 0;
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ldata->column = 0;
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@ -375,6 +375,7 @@ static inline void tty_ldisc_put(struct tty_ldisc *ld)
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void tty_ldisc_enable(struct tty_struct *tty)
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void tty_ldisc_enable(struct tty_struct *tty)
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{
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{
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clear_bit(TTY_LDISC_HALTED, &tty->flags);
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set_bit(TTY_LDISC, &tty->flags);
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set_bit(TTY_LDISC, &tty->flags);
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clear_bit(TTY_LDISC_CHANGING, &tty->flags);
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clear_bit(TTY_LDISC_CHANGING, &tty->flags);
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wake_up(&tty_ldisc_wait);
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wake_up(&tty_ldisc_wait);
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@ -513,8 +514,11 @@ static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old)
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static int tty_ldisc_halt(struct tty_struct *tty)
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static int tty_ldisc_halt(struct tty_struct *tty)
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{
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{
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int scheduled;
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clear_bit(TTY_LDISC, &tty->flags);
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clear_bit(TTY_LDISC, &tty->flags);
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return cancel_work_sync(&tty->port->buf.work);
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scheduled = cancel_work_sync(&tty->port->buf.work);
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set_bit(TTY_LDISC_HALTED, &tty->flags);
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return scheduled;
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}
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}
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/**
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/**
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@ -820,6 +824,7 @@ void tty_ldisc_hangup(struct tty_struct *tty)
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clear_bit(TTY_LDISC, &tty->flags);
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clear_bit(TTY_LDISC, &tty->flags);
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tty_unlock(tty);
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tty_unlock(tty);
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cancel_work_sync(&tty->port->buf.work);
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cancel_work_sync(&tty->port->buf.work);
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set_bit(TTY_LDISC_HALTED, &tty->flags);
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mutex_unlock(&tty->ldisc_mutex);
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mutex_unlock(&tty->ldisc_mutex);
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retry:
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retry:
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tty_lock(tty);
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tty_lock(tty);
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@ -315,6 +315,7 @@ struct tty_file_private {
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#define TTY_NO_WRITE_SPLIT 17 /* Preserve write boundaries to driver */
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#define TTY_NO_WRITE_SPLIT 17 /* Preserve write boundaries to driver */
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#define TTY_HUPPED 18 /* Post driver->hangup() */
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#define TTY_HUPPED 18 /* Post driver->hangup() */
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#define TTY_HUPPING 21 /* ->hangup() in progress */
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#define TTY_HUPPING 21 /* ->hangup() in progress */
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#define TTY_LDISC_HALTED 22 /* Line discipline is halted */
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#define TTY_WRITE_FLUSH(tty) tty_write_flush((tty))
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#define TTY_WRITE_FLUSH(tty) tty_write_flush((tty))
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