From: "Ahmed S. Darwish" <ahmed.darwish@xxxxxxxxx> [ Upstream commit 2fec5104f9c61de4cf2205aa355101e19a81f490 ] 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 <ahmed.darwish@xxxxxxxxx> Cc: linux-stable <stable@xxxxxxxxxxxxxxx> Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx> --- 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 8b255e7..5d77795 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 <olivier@xxxxxxxxx> */ +#include <linux/kernel.h> #include <linux/completion.h> #include <linux/module.h> #include <linux/netdevice.h> @@ -403,8 +404,15 @@ 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, @@ -983,8 +991,19 @@ 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"); @@ -992,7 +1011,6 @@ static void kvaser_usb_read_bulk_callback(struct urb *urb) } kvaser_usb_handle_message(dev, msg); - pos += msg->len; } -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html