Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030235AbaGOXhr (ORCPT ); Tue, 15 Jul 2014 19:37:47 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:45499 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933958AbaGOXOM (ORCPT ); Tue, 15 Jul 2014 19:14:12 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Aaro Koskinen , Seth Bollinger , "David S. Miller" , Sam Ravnborg , Thomas Bogendoerfer , Peter Hurley Subject: [PATCH 3.15 06/84] serial: Test for no tx data on tx restart Date: Tue, 15 Jul 2014 16:17:03 -0700 Message-Id: <20140715231713.378305678@linuxfoundation.org> X-Mailer: git-send-email 2.0.0.254.g50f84e3 In-Reply-To: <20140715231713.193785557@linuxfoundation.org> References: <20140715231713.193785557@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Peter Hurley commit c557d392fbf5badd693ea1946a4317c87a26a716 upstream. Commit 717f3bbab3c7628736ef738fdbf3d9a28578c26c, 'serial_core: Fix conditional start_tx on ring buffer not empty' exposes an incorrect assumption in several drivers' start_tx methods; the tx ring buffer can, in fact, be empty when restarting tx while performing flow control. Affected drivers: sunsab.c ip22zilog.c pmac_zilog.c sunzilog.c m32r_sio.c imx.c Other in-tree serial drivers either are not affected or already test for empty tx ring buffer before transmitting. Test for empty tx ring buffer in start_tx() method, after transmitting x_char (if applicable). Reported-by: Aaro Koskinen Cc: Seth Bollinger Cc: "David S. Miller" Cc: Sam Ravnborg Cc: Thomas Bogendoerfer Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/imx.c | 3 +++ drivers/tty/serial/ip22zilog.c | 2 ++ drivers/tty/serial/m32r_sio.c | 8 +++++--- drivers/tty/serial/pmac_zilog.c | 3 +++ drivers/tty/serial/sunsab.c | 3 +++ drivers/tty/serial/sunzilog.c | 2 ++ 6 files changed, 18 insertions(+), 3 deletions(-) --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -563,6 +563,9 @@ static void imx_start_tx(struct uart_por struct imx_port *sport = (struct imx_port *)port; unsigned long temp; + if (uart_circ_empty(&port.state->xmit)) + return; + if (USE_IRDA(sport)) { /* half duplex in IrDA mode; have to disable receive mode */ temp = readl(sport->port.membase + UCR4); --- a/drivers/tty/serial/ip22zilog.c +++ b/drivers/tty/serial/ip22zilog.c @@ -603,6 +603,8 @@ static void ip22zilog_start_tx(struct ua } else { struct circ_buf *xmit = &port->state->xmit; + if (uart_circ_empty(xmit)) + return; writeb(xmit->buf[xmit->tail], &channel->data); ZSDELAY(); ZS_WSYNC(channel); --- a/drivers/tty/serial/m32r_sio.c +++ b/drivers/tty/serial/m32r_sio.c @@ -266,9 +266,11 @@ static void m32r_sio_start_tx(struct uar if (!(up->ier & UART_IER_THRI)) { up->ier |= UART_IER_THRI; serial_out(up, UART_IER, up->ier); - serial_out(up, UART_TX, xmit->buf[xmit->tail]); - xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); - up->port.icount.tx++; + if (!uart_circ_empty(xmit)) { + serial_out(up, UART_TX, xmit->buf[xmit->tail]); + xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); + up->port.icount.tx++; + } } while((serial_in(up, UART_LSR) & UART_EMPTY) != UART_EMPTY); #else --- a/drivers/tty/serial/pmac_zilog.c +++ b/drivers/tty/serial/pmac_zilog.c @@ -653,6 +653,8 @@ static void pmz_start_tx(struct uart_por } else { struct circ_buf *xmit = &port->state->xmit; + if (uart_circ_empty(xmit)) + goto out; write_zsdata(uap, xmit->buf[xmit->tail]); zssync(uap); xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); @@ -661,6 +663,7 @@ static void pmz_start_tx(struct uart_por if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) uart_write_wakeup(&uap->port); } + out: pmz_debug("pmz: start_tx() done.\n"); } --- a/drivers/tty/serial/sunsab.c +++ b/drivers/tty/serial/sunsab.c @@ -427,6 +427,9 @@ static void sunsab_start_tx(struct uart_ struct circ_buf *xmit = &up->port.state->xmit; int i; + if (uart_circ_empty(xmit)) + return; + up->interrupt_mask1 &= ~(SAB82532_IMR1_ALLS|SAB82532_IMR1_XPR); writeb(up->interrupt_mask1, &up->regs->w.imr1); --- a/drivers/tty/serial/sunzilog.c +++ b/drivers/tty/serial/sunzilog.c @@ -703,6 +703,8 @@ static void sunzilog_start_tx(struct uar } else { struct circ_buf *xmit = &port->state->xmit; + if (uart_circ_empty(xmit)) + return; writeb(xmit->buf[xmit->tail], &channel->data); ZSDELAY(); ZS_WSYNC(channel); -- 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/