This is a note to let you know that I've just added the patch titled
can: gs_usb: fix busy loop if no more TX context is available
to the 3.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
can-gs_usb-fix-busy-loop-if-no-more-tx-context-is-available.patch
and it can be found in the queue-3.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 97819f943063b622eca44d3644067c190dc75039 Mon Sep 17 00:00:00 2001
From: Wolfgang Grandegger <wg@xxxxxxxxxxxxxx>
Date: Thu, 14 Sep 2017 18:37:14 +0200
Subject: can: gs_usb: fix busy loop if no more TX context is available
From: Wolfgang Grandegger <wg@xxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxx>
Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/can/usb/gs_usb.c | 10 ++--------
1 file changed, 2 insertions(+), 8 deletions(-)
--- 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
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->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)
Patches currently in stable-queue which might be from wg@xxxxxxxxxxxxxx are
queue-3.18/can-gs_usb-fix-busy-loop-if-no-more-tx-context-is-available.patch