can: gs_usb: fix busy loop if no more TX context is available

commit 97819f943063b622eca44d3644067c190dc75039 upstream.

If sending messages with no cable connected, it quickly happens that
there is no more TX context available. Then "gs_can_start_xmit()"
returns with "NETDEV_TX_BUSY" and the upper layer does retry
immediately keeping the CPU busy. To fix that issue, I moved
"atomic_dec(&dev->active_tx_urbs)" from "gs_usb_xmit_callback()" to
the TX done handling in "gs_usb_receive_bulk_callback()". Renaming
"active_tx_urbs" to "active_tx_contexts" and moving it into
"gs_[alloc|free]_tx_context()" would also make sense.

Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c
index 991aff587f6380e4bb7b4408f948493db3ec21a1..94adbcf74e7c8c3d9520ac425e9df96d19417f21 100644 (file)
--- a/drivers/net/can/usb/gs_usb.c
+++ b/drivers/net/can/usb/gs_usb.c
@@ -356,6 +356,8 @@ static void gs_usb_recieve_bulk_callback(struct urb *urb)
 
                gs_free_tx_context(txc);
 
+               atomic_dec(&dev->active_tx_urbs);
+
                netif_wake_queue(netdev);
        }
 
@@ -444,14 +446,6 @@ static void gs_usb_xmit_callback(struct urb *urb)
                          urb->transfer_buffer_length,
                          urb->transfer_buffer,
                          urb->transfer_dma);
-
-       atomic_dec(&dev->active_tx_urbs);
-
-       if (!netif_device_present(netdev))
-               return;
-
-       if (netif_queue_stopped(netdev))
-               netif_wake_queue(netdev);
 }
 
 static netdev_tx_t gs_can_start_xmit(struct sk_buff *skb, struct net_device *netdev)