From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc Kleine-Budde Subject: [PATCH 11/11] can: gs_usb: fix busy loop if no more TX context is available Date: Thu, 19 Oct 2017 13:19:45 +0200 Message-ID: <20171019111945.13580-12-mkl@pengutronix.de> References: <20171019111945.13580-1-mkl@pengutronix.de> Return-path: In-Reply-To: <20171019111945.13580-1-mkl@pengutronix.de> Sender: stable-owner@vger.kernel.org To: netdev@vger.kernel.org Cc: davem@davemloft.net, linux-can@vger.kernel.org, kernel@pengutronix.de, Wolfgang Grandegger , linux-stable , Marc Kleine-Budde List-Id: linux-can.vger.kernel.org From: Wolfgang Grandegger 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 Cc: linux-stable Signed-off-by: Marc Kleine-Budde --- 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 afcc1312dbaf..68ac3e88a8ce 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, -- 2.14.2