From: Jiri Slaby This patch was intorduced in mxser to 1.9.1 conversion, but causes endless sleep in tcdrain userspace call. Thanks to Sergei Organov for testing and pointing this out. Signed-off-by: Jiri Slaby Cc: Alan Cox Signed-off-by: Andrew Morton --- drivers/char/mxser_new.c | 27 +++++++-------------------- 1 file changed, 7 insertions(+), 20 deletions(-) diff -puN drivers/char/mxser_new.c~char-mxser_new-reverse-if-else-paths-patch drivers/char/mxser_new.c --- a/drivers/char/mxser_new.c~char-mxser_new-reverse-if-else-paths-patch +++ a/drivers/char/mxser_new.c @@ -1218,12 +1218,7 @@ static int mxser_write_room(struct tty_s static int mxser_chars_in_buffer(struct tty_struct *tty) { struct mxser_port *info = tty->driver_data; - int len = info->xmit_cnt; - - if (!(inb(info->ioaddr + UART_LSR) & UART_LSR_THRE)) - len++; - - return len; + return info->xmit_cnt; } static void mxser_flush_buffer(struct tty_struct *tty) @@ -1953,7 +1948,7 @@ static void mxser_stoprx(struct tty_stru if (info->board->chip_flag) { info->IER &= ~MOXA_MUST_RECV_ISR; outb(info->IER, info->ioaddr + UART_IER); - } else if (!(info->flags & ASYNC_CLOSING)) { + } else { info->x_char = STOP_CHAR(tty); outb(0, info->ioaddr + UART_IER); info->IER |= UART_IER_THRI; @@ -1990,7 +1985,7 @@ static void mxser_unthrottle(struct tty_ if (info->board->chip_flag) { info->IER |= MOXA_MUST_RECV_ISR; outb(info->IER, info->ioaddr + UART_IER); - } else if (!(info->flags & ASYNC_CLOSING)) { + } else { info->x_char = START_CHAR(tty); outb(0, info->ioaddr + UART_IER); info->IER |= UART_IER_THRI; @@ -2265,10 +2260,8 @@ static void mxser_receive_chars(struct m flag = TTY_OVERRUN; /* added by casper 1/11/2000 */ port->icount.overrun++; - } else - flags = TTY_BREAK; - } else - flags = 0; + } + } tty_insert_flip_char(tty, ch, flag); cnt++; if (cnt >= recv_room) { @@ -2324,14 +2317,8 @@ static void mxser_transmit_chars(struct if (port->xmit_buf == 0) goto unlock; - if (port->xmit_cnt == 0) { - if (port->xmit_cnt < WAKEUP_CHARS) { /* XXX what's this for?? */ - set_bit(MXSER_EVENT_TXLOW, &port->event); - schedule_work(&port->tqueue); - } - goto unlock; - } - if (port->tty->stopped || (port->tty->hw_stopped && + if ((port->xmit_cnt <= 0) || port->tty->stopped || + (port->tty->hw_stopped && (port->type != PORT_16550A) && (!port->board->chip_flag))) { port->IER &= ~UART_IER_THRI; _