This is a note to let you know that I've just added the patch titled
can: kvaser_usb: Read all messages in a bulk-in URB buffer
to the 3.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
can-kvaser_usb-read-all-messages-in-a-bulk-in-urb-buffer.patch
and it can be found in the queue-3.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 2fec5104f9c61de4cf2205aa355101e19a81f490 Mon Sep 17 00:00:00 2001
From: "Ahmed S. Darwish" <ahmed.darwish@xxxxxxxxx>
Date: Thu, 26 Feb 2015 10:22:02 -0500
Subject: can: kvaser_usb: Read all messages in a bulk-in URB buffer
From: "Ahmed S. Darwish" <ahmed.darwish@xxxxxxxxx>
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 <ahmed.darwish@xxxxxxxxx>
Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/can/usb/kvaser_usb.c | 28 +++++++++++++++++++++++-----
1 file changed, 23 insertions(+), 5 deletions(-)
--- 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 str
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,
@@ -980,8 +988,19 @@ static void kvaser_usb_read_bulk_callbac
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");
@@ -989,7 +1008,6 @@ static void kvaser_usb_read_bulk_callbac
}
kvaser_usb_handle_message(dev, msg);
-
pos += msg->len;
}
Patches currently in stable-queue which might be from ahmed.darwish@xxxxxxxxx are
queue-3.19/can-kvaser_usb-read-all-messages-in-a-bulk-in-urb-buffer.patch
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