From 6f0eefab853bc819ef2818db7e506d587136c123 Mon Sep 17 00:00:00 2001 From: Wolfgang Grandegger Date: Thu, 14 Sep 2017 18:37:14 +0200 Subject: [PATCH] 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 Signed-off-by: Marc Kleine-Budde Signed-off-by: Greg Kroah-Hartman --- drivers/net/can/usb/gs_usb.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-) diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c index 05369dc..eea9aea 100644 --- a/drivers/net/can/usb/gs_usb.c +++ b/drivers/net/can/usb/gs_usb.c @@ -375,6 +375,8 @@ static void gs_usb_receive_bulk_callback(struct urb *urb) gs_free_tx_context(txc); + atomic_dec(&dev->active_tx_urbs); + netif_wake_queue(netdev); } @@ -463,14 +465,6 @@ 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, -- 2.7.4