Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932775AbbDGXUP (ORCPT ); Tue, 7 Apr 2015 19:20:15 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:55743 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754443AbbDGWwl (ORCPT ); Tue, 7 Apr 2015 18:52:41 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: "Ahmed S. Darwish" , Marc Kleine-Budde , Kamal Mostafa Subject: [PATCH 3.13.y-ckt 073/156] can: kvaser_usb: Read all messages in a bulk-in URB buffer Date: Tue, 7 Apr 2015 15:50:10 -0700 Message-Id: <1428447093-3282-74-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1428447093-3282-1-git-send-email-kamal@canonical.com> References: <1428447093-3282-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3512 Lines: 100 3.13.11-ckt19 -stable review patch. If anyone has any objections, please let me know. ------------------ From: "Ahmed S. Darwish" commit 2fec5104f9c61de4cf2205aa355101e19a81f490 upstream. The Kvaser firmware can only read and write messages that are not crossing the USB endpoint's wMaxPacketSize boundary. While receiving commands from the CAN device, if the next command in the same URB buffer crossed that max packet size boundary, the firmware puts a zero-length placeholder command in its place then moves the real command to the next boundary mark. The driver did not recognize such behavior, leading to missing a good number of rx events during a heavy rx load session. Moreover, a tx URB context only gets freed upon receiving its respective tx ACK event. Over time, the free tx URB contexts pool gets depleted due to the missing ACK events. Consequently, the netif transmission queue gets __permanently__ stopped; no frames could be sent again except after restarting the CAN newtwork interface. Signed-off-by: Ahmed S. Darwish Signed-off-by: Marc Kleine-Budde Signed-off-by: Kamal Mostafa --- drivers/net/can/usb/kvaser_usb.c | 28 +++++++++++++++++++++++----- 1 file changed, 23 insertions(+), 5 deletions(-) diff --git a/drivers/net/can/usb/kvaser_usb.c b/drivers/net/can/usb/kvaser_usb.c index bc8506d..3b2623b 100644 --- a/drivers/net/can/usb/kvaser_usb.c +++ b/drivers/net/can/usb/kvaser_usb.c @@ -12,6 +12,7 @@ * Copyright (C) 2012 Olivier Sobrie */ +#include #include #include #include @@ -397,8 +398,15 @@ static int kvaser_usb_wait_msg(const struct kvaser_usb *dev, u8 id, while (pos <= actual_len - MSG_HEADER_LEN) { tmp = buf + pos; - if (!tmp->len) - break; + /* Handle messages crossing the USB endpoint max packet + * size boundary. Check kvaser_usb_read_bulk_callback() + * for further details. + */ + if (tmp->len == 0) { + pos = round_up(pos, + dev->bulk_in->wMaxPacketSize); + continue; + } if (pos + tmp->len > actual_len) { dev_err(dev->udev->dev.parent, "Format error\n"); @@ -974,8 +982,19 @@ static void kvaser_usb_read_bulk_callback(struct urb *urb) while (pos <= urb->actual_length - MSG_HEADER_LEN) { msg = urb->transfer_buffer + pos; - if (!msg->len) - break; + /* The Kvaser firmware can only read and write messages that + * does not cross the USB's endpoint wMaxPacketSize boundary. + * If a follow-up command crosses such boundary, firmware puts + * a placeholder zero-length command in its place then aligns + * the real command to the next max packet size. + * + * Handle such cases or we're going to miss a significant + * number of events in case of a heavy rx load on the bus. + */ + if (msg->len == 0) { + pos = round_up(pos, dev->bulk_in->wMaxPacketSize); + continue; + } if (pos + msg->len > urb->actual_length) { dev_err(dev->udev->dev.parent, "Format error\n"); @@ -983,7 +1002,6 @@ static void kvaser_usb_read_bulk_callback(struct urb *urb) } kvaser_usb_handle_message(dev, msg); - pos += msg->len; } -- 1.9.1 -- 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/