Merge tag 'linux-can-fixes-for-4.5-20160221' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can

Marc Kleine-Budde says:

====================
pull-request: can 2016-02-21

this is a pull reqeust of one patch for net/master.

The patch is by Gerhard Uttenthaler and fixes a potential tx overflow in the
ems_usb driver.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 4 deletions

diff --git a/drivers/net/can/usb/ems_usb.c b/drivers/net/can/usb/ems_usb.c
index fc5b75675cd8..eb7192fab593 100644
--- a/drivers/net/can/usb/ems_usb.c
+++ b/drivers/net/can/usb/ems_usb.c
@@ -117,6 +117,9 @@ MODULE_LICENSE("GPL v2");
  */
 #define EMS_USB_ARM7_CLOCK 8000000
 
+#define CPC_TX_QUEUE_TRIGGER_LOW        25
+#define CPC_TX_QUEUE_TRIGGER_HIGH       35
+
 /*
  * CAN-Message representation in a CPC_MSG. Message object type is
  * CPC_MSG_TYPE_CAN_FRAME or CPC_MSG_TYPE_RTR_FRAME or
@@ -278,6 +281,11 @@ static void ems_usb_read_interrupt_callback(struct urb *urb)
         switch (urb->status) {
         case 0:
                 dev->free_slots = dev->intr_in_buffer[1];
+                if(dev->free_slots > CPC_TX_QUEUE_TRIGGER_HIGH){
+                        if (netif_queue_stopped(netdev)){
+                                netif_wake_queue(netdev);
+                        }
+                }
                 break;
 
         case -ECONNRESET: /* unlink */
@@ -526,8 +534,6 @@ static void ems_usb_write_bulk_callback(struct urb *urb)
         /* Release context */
         context->echo_index = MAX_TX_URBS;
 
-        if (netif_queue_stopped(netdev))
-                netif_wake_queue(netdev);
 }
 
 /*
@@ -587,7 +593,7 @@ static int ems_usb_start(struct ems_usb *dev)
         int err, i;
 
         dev->intr_in_buffer[0] = 0;
-        dev->free_slots = 15; /* initial size */
+        dev->free_slots = 50; /* initial size */
 
         for (i = 0; i < MAX_RX_URBS; i++) {
                 struct urb *urb = NULL;
@@ -835,7 +841,7 @@ static netdev_tx_t ems_usb_start_xmit(struct sk_buff *skb, struct net_device *ne
 
                 /* Slow down tx path */
                 if (atomic_read(&dev->active_tx_urbs) >= MAX_TX_URBS ||
-                    dev->free_slots < 5) {
+                    dev->free_slots < CPC_TX_QUEUE_TRIGGER_LOW) {
                         netif_stop_queue(netdev);
                 }
         }