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authorAhmed S. Darwish <ahmed.darwish@valeo.com>2015-02-26 10:22:02 -0500
committerMarc Kleine-Budde <mkl@pengutronix.de>2015-03-09 10:22:24 +0100
commit2fec5104f9c61de4cf2205aa355101e19a81f490 (patch)
tree7c3fa357f160f9bf6dc44d6d4a87bc73ac4117a5 /drivers
parentdeb2701cf704a2fd03a8b598bf73df3edb08818d (diff)
downloadkernel-2fec5104f9c61de4cf2205aa355101e19a81f490.tar.gz
can: kvaser_usb: Read all messages in a bulk-in URB buffer
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@valeo.com> Cc: linux-stable <stable@vger.kernel.org> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/net/can/usb/kvaser_usb.c28
1 files changed, 23 insertions, 5 deletions
diff --git a/drivers/net/can/usb/kvaser_usb.c b/drivers/net/can/usb/kvaser_usb.c
index d986fe83c40d..a316fa4b91ab 100644
--- a/drivers/net/can/usb/kvaser_usb.c
+++ b/drivers/net/can/usb/kvaser_usb.c
@@ -14,6 +14,7 @@
* Copyright (C) 2015 Valeo S.A.
*/
+#include <linux/kernel.h>
#include <linux/completion.h>
#include <linux/module.h>
#include <linux/netdevice.h>
@@ -584,8 +585,15 @@ 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,
@@ -1316,8 +1324,19 @@ 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");
@@ -1325,7 +1344,6 @@ static void kvaser_usb_read_bulk_callback(struct urb *urb)
}
kvaser_usb_handle_message(dev, msg);
-
pos += msg->len;
}