r8169: fix early queue wake-up.
With infinite gratitude to Eric Dumazet for allowing me to identify the error. Signed-off-by: Francois Romieu <romieu@fr.zoreil.com> Acked-by: Eric Dumazet <eric.dumazet@gmail.com> Cc: Hayes Wang <hayeswang@realtek.com>
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@ -5559,7 +5559,18 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
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mmiowb();
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if (TX_BUFFS_AVAIL(tp) < MAX_SKB_FRAGS) {
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/* Avoid wrongly optimistic queue wake-up: rtl_tx thread must
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* not miss a ring update when it notices a stopped queue.
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*/
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smp_wmb();
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netif_stop_queue(dev);
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/* Sync with rtl_tx:
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* - publish queue status and cur_tx ring index (write barrier)
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* - refresh dirty_tx ring index (read barrier).
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* May the current thread have a pessimistic view of the ring
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* status and forget to wake up queue, a racing rtl_tx thread
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* can't.
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*/
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smp_mb();
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if (TX_BUFFS_AVAIL(tp) >= MAX_SKB_FRAGS)
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netif_wake_queue(dev);
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@ -5659,6 +5670,13 @@ static void rtl_tx(struct net_device *dev, struct rtl8169_private *tp)
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if (tp->dirty_tx != dirty_tx) {
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tp->dirty_tx = dirty_tx;
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/* Sync with rtl8169_start_xmit:
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* - publish dirty_tx ring index (write barrier)
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* - refresh cur_tx ring index and queue status (read barrier)
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* May the current thread miss the stopped queue condition,
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* a racing xmit thread can only have a right view of the
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* ring status.
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*/
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smp_mb();
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if (netif_queue_stopped(dev) &&
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(TX_BUFFS_AVAIL(tp) >= MAX_SKB_FRAGS)) {
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