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

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>
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Wolfgang Grandegger 2017-09-14 18:37:14 +02:00 committed by Marc Kleine-Budde
parent 72d92e865d
commit 97819f9430
1 changed files with 2 additions and 8 deletions
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10
drivers/net/can/usb/gs_usb.c
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@ -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,