Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967477Ab3HIB6m (ORCPT ); Thu, 8 Aug 2013 21:58:42 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:55633 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S967372Ab3HIB6j (ORCPT ); Thu, 8 Aug 2013 21:58:39 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= Subject: [ 022/102] serial/mxs-auart: fix race condition in interrupt handler Date: Thu, 8 Aug 2013 18:56:58 -0700 Message-Id: <20130809015015.175626439@linuxfoundation.org> X-Mailer: git-send-email 1.8.3.rc0.20.gb99dd2e In-Reply-To: <20130809015010.208118575@linuxfoundation.org> References: <20130809015010.208118575@linuxfoundation.org> User-Agent: quilt/0.60-5.1.1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2026 Lines: 66 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Uwe Kleine-König commit d970d7fe65adff5efe75b4a73c4ffc9be57089f7 upstream. The handler needs to ack the pending events before actually handling them. Otherwise a new event might come in after it it considered non-pending or handled and is acked then without being handled. So this event is only noticed when the next interrupt happens. Without this patch an i.MX28 based machine running an rt-patched kernel regularly hangs during boot. Signed-off-by: Uwe Kleine-König Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/mxs-auart.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) --- a/drivers/tty/serial/mxs-auart.c +++ b/drivers/tty/serial/mxs-auart.c @@ -678,11 +678,18 @@ static void mxs_auart_settermios(struct static irqreturn_t mxs_auart_irq_handle(int irq, void *context) { - u32 istatus, istat; + u32 istat; struct mxs_auart_port *s = context; u32 stat = readl(s->port.membase + AUART_STAT); - istatus = istat = readl(s->port.membase + AUART_INTR); + istat = readl(s->port.membase + AUART_INTR); + + /* ack irq */ + writel(istat & (AUART_INTR_RTIS + | AUART_INTR_TXIS + | AUART_INTR_RXIS + | AUART_INTR_CTSMIS), + s->port.membase + AUART_INTR_CLR); if (istat & AUART_INTR_CTSMIS) { uart_handle_cts_change(&s->port, stat & AUART_STAT_CTS); @@ -702,12 +709,6 @@ static irqreturn_t mxs_auart_irq_handle( istat &= ~AUART_INTR_TXIS; } - writel(istatus & (AUART_INTR_RTIS - | AUART_INTR_TXIS - | AUART_INTR_RXIS - | AUART_INTR_CTSMIS), - s->port.membase + AUART_INTR_CLR); - return IRQ_HANDLED; } -- 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/