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;
         }