From dcad9ee9e0663d74a89b25b987f9c7be86432812 Mon Sep 17 00:00:00 2001 From: Yunsheng Lin Date: Fri, 14 May 2021 11:17:01 +0800 Subject: net: sched: fix tx action reschedule issue with stopped queue The netdev qeueue might be stopped when byte queue limit has reached or tx hw ring is full, net_tx_action() may still be rescheduled if STATE_MISSED is set, which consumes unnecessary cpu without dequeuing and transmiting any skb because the netdev queue is stopped, see qdisc_run_end(). This patch fixes it by checking the netdev queue state before calling qdisc_run() and clearing STATE_MISSED if netdev queue is stopped during qdisc_run(), the net_tx_action() is rescheduled again when netdev qeueue is restarted, see netif_tx_wake_queue(). As there is time window between netif_xmit_frozen_or_stopped() checking and STATE_MISSED clearing, between which STATE_MISSED may set by net_tx_action() scheduled by netif_tx_wake_queue(), so set the STATE_MISSED again if netdev queue is restarted. Fixes: 6b3ba9146fe6 ("net: sched: allow qdiscs to handle locking") Reported-by: Michal Kubecek Acked-by: Jakub Kicinski Signed-off-by: Yunsheng Lin Signed-off-by: David S. Miller --- net/core/dev.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'net/core') diff --git a/net/core/dev.c b/net/core/dev.c index d596cd746353..ef8cf7619baf 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -3853,7 +3853,8 @@ static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q, if (q->flags & TCQ_F_NOLOCK) { rc = q->enqueue(skb, q, &to_free) & NET_XMIT_MASK; - qdisc_run(q); + if (likely(!netif_xmit_frozen_or_stopped(txq))) + qdisc_run(q); if (unlikely(to_free)) kfree_skb_list(to_free); -- cgit v1.2.3