Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752105AbbLMAil (ORCPT ); Sat, 12 Dec 2015 19:38:41 -0500 Received: from mail-pa0-f53.google.com ([209.85.220.53]:36756 "EHLO mail-pa0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751376AbbLMAgu (ORCPT ); Sat, 12 Dec 2015 19:36:50 -0500 From: Peter Hurley To: Greg Kroah-Hartman Cc: Jiri Slaby , linux-kernel@vger.kernel.org, Peter Hurley Subject: [PATCH 4/8] serial: core: Take port mutex for send_xchar() tty method Date: Sat, 12 Dec 2015 16:36:28 -0800 Message-Id: <1449966992-4033-5-git-send-email-peter@hurleysoftware.com> X-Mailer: git-send-email 2.6.3 In-Reply-To: <1449966992-4033-1-git-send-email-peter@hurleysoftware.com> References: <1449966992-4033-1-git-send-email-peter@hurleysoftware.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2702 Lines: 83 Prepare for separate methods of preventing unsafe uart port access when sending xchar; claim port mutex for the tty ops method (which might sleep) and rcu for the throttle/unthrottle uses. The implied limitation is that uart drivers which support AUTOXOFF flow control cannot define a send_xchar() method that sleeps. Signed-off-by: Peter Hurley --- drivers/tty/serial/serial_core.c | 30 +++++++++++++++++++----------- 1 file changed, 19 insertions(+), 11 deletions(-) diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 4430518..806eba81 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -610,23 +610,31 @@ static void uart_flush_buffer(struct tty_struct *tty) * This function is used to send a high-priority XON/XOFF character to * the device */ -static void uart_send_xchar(struct tty_struct *tty, char ch) +static void __uart_send_xchar(struct uart_port *uport, char ch) { - struct uart_state *state = tty->driver_data; - struct uart_port *port = state->uart_port; unsigned long flags; - if (port->ops->send_xchar) - port->ops->send_xchar(port, ch); + if (uport->ops->send_xchar) + uport->ops->send_xchar(uport, ch); else { - spin_lock_irqsave(&port->lock, flags); - port->x_char = ch; + spin_lock_irqsave(&uport->lock, flags); + uport->x_char = ch; if (ch) - port->ops->start_tx(port); - spin_unlock_irqrestore(&port->lock, flags); + uport->ops->start_tx(port); + spin_unlock_irqrestore(&uport->lock, flags); } } +static void uart_send_xchar(struct tty_struct *tty, char ch) +{ + struct uart_state *state = tty->driver_data; + struct uart_port *uport = state->uart_port; + + mutex_lock(&state->port.mutex); + __uart_send_xchar(uport, ch); + mutex_unlock(&state->port.mutex); +} + static void uart_throttle(struct tty_struct *tty) { struct uart_state *state = tty->driver_data; @@ -644,7 +652,7 @@ static void uart_throttle(struct tty_struct *tty) } if (mask & UPSTAT_AUTOXOFF) - uart_send_xchar(tty, STOP_CHAR(tty)); + __uart_send_xchar(port, STOP_CHAR(tty)); if (mask & UPSTAT_AUTORTS) uart_clear_mctrl(port, TIOCM_RTS); @@ -667,7 +675,7 @@ static void uart_unthrottle(struct tty_struct *tty) } if (mask & UPSTAT_AUTOXOFF) - uart_send_xchar(tty, START_CHAR(tty)); + __uart_send_xchar(port, START_CHAR(tty)); if (mask & UPSTAT_AUTORTS) uart_set_mctrl(port, TIOCM_RTS); -- 2.6.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/