can: ems_usb: Fix possible tx overflow
This patch fixes the problem that more CAN messages could be sent to the
interface as could be send on the CAN bus. This was more likely for slow baud
rates. The sleeping _start_xmit was woken up in the _write_bulk_callback. Under
heavy TX load this produced another bulk transfer without checking the
free_slots variable and hence caused the overflow in the interface.
Signed-off-by: Gerhard Uttenthaler <uttenthaler@ems-wuensche.com>
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
diff --git a/drivers/net/can/usb/ems_usb.c b/drivers/net/can/usb/ems_usb.c
index fc5b756..eb7192f 100644
--- a/drivers/net/can/usb/ems_usb.c
+++ b/drivers/net/can/usb/ems_usb.c
@@ -117,6 +117,9 @@
*/
#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 @@
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 @@
/* Release context */
context->echo_index = MAX_TX_URBS;
- if (netif_queue_stopped(netdev))
- netif_wake_queue(netdev);
}
/*
@@ -587,7 +593,7 @@
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 @@
/* 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);
}
}