Commit 9f46d28c authored Feb 25, 2021 by Joakim Zhang Committed by Greg Kroah-Hartman Mar 17, 2021

net: stmmac: fix watchdog timeout during suspend/resume stress test



commit c511819d138de38e1637eedb645c207e09680d0f upstream.

stmmac_xmit() call stmmac_tx_timer_arm() at the end to modify tx timer to
do the transmission cleanup work. Imagine such a situation, stmmac enters
suspend immediately after tx timer modified, it's expire callback
stmmac_tx_clean() would not be invoked. This could affect BQL, since
netdev_tx_sent_queue() has been called, but netdev_tx_completed_queue()
have not been involved, as a result, dql_avail(&dev_queue->dql) finally
always return a negative value.

__dev_queue_xmit->__dev_xmit_skb->qdisc_run->__qdisc_run->qdisc_restart->dequeue_skb:
	if ((q->flags & TCQ_F_ONETXQUEUE) &&
		netif_xmit_frozen_or_stopped(txq)) // __QUEUE_STATE_STACK_XOFF is set

Net core will stop transmitting any more. Finillay, net watchdong would timeout.
To fix this issue, we should call netdev_tx_reset_queue() in stmmac_resume().

Fixes: 54139cf3 ("net: stmmac: adding multiple buffers for rx")
Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 42b8f308

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -4566,6 +4566,8 @@ static void stmmac_reset_queues_param(struct stmmac_priv *priv)
		tx_q->cur_tx = 0;
		tx_q->dirty_tx = 0;
		tx_q->mss = 0;

		netdev_tx_reset_queue(netdev_get_tx_queue(priv->dev, queue));
		}
		}