FAILED: patch "[PATCH] net: stmmac: fix watchdog timeout during suspend/resume" failed to apply to 4.14-stable tree

The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From c511819d138de38e1637eedb645c207e09680d0f Mon Sep 17 00:00:00 2001
From: Joakim Zhang <[email protected]>
Date: Thu, 25 Feb 2021 17:01:11 +0800
Subject: [PATCH] net: stmmac: fix watchdog timeout during suspend/resume
stress test

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().

index 26b971cd4da5..12ed337a239b 100644
@@ -5257,6 +5257,8 @@ 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));
 	}
 }