From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754283Ab3L2CMX (ORCPT ); Sat, 28 Dec 2013 21:12:23 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:55725 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753986Ab3L2CLZ (ORCPT ); Sat, 28 Dec 2013 21:11:25 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Marc Kleine-Budde" , "Markus Pargmann" Date: Sun, 29 Dec 2013 03:08:43 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 020/185] can: c_can: Fix RX message handling, handle lost message before EOB In-Reply-To: X-SA-Exim-Connect-IP: 31.18.200.85 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.54-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Markus Pargmann commit 5d0f801a2ccec3b1fdabc3392c8d99ed0413d216 upstream. If we handle end of block messages with higher priority than a lost message, we can run into an endless interrupt loop. This is reproducable with a am335x processor and "cansequence -r" at 1Mbit. As soon as we loose a packet we can't escape from an interrupt loop. This patch fixes the problem by handling lost packets before EOB packets. Signed-off-by: Markus Pargmann Signed-off-by: Marc Kleine-Budde Signed-off-by: Ben Hutchings --- drivers/net/can/c_can/c_can.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/drivers/net/can/c_can/c_can.c +++ b/drivers/net/can/c_can/c_can.c @@ -764,9 +764,6 @@ static int c_can_do_rx_poll(struct net_d msg_ctrl_save = priv->read_reg(priv, &priv->regs->ifregs[0].msg_cntrl); - if (msg_ctrl_save & IF_MCONT_EOB) - return num_rx_pkts; - if (msg_ctrl_save & IF_MCONT_MSGLST) { c_can_handle_lost_msg_obj(dev, 0, msg_obj); num_rx_pkts++; @@ -774,6 +771,9 @@ static int c_can_do_rx_poll(struct net_d continue; } + if (msg_ctrl_save & IF_MCONT_EOB) + return num_rx_pkts; + if (!(msg_ctrl_save & IF_MCONT_NEWDAT)) continue;