Revert "r8169: make use of xmit_more and __netdev_sent_queue"

This reverts commit e02f711790a40502f424448f3bc45862e6a1926c.

Sander reported a regression causing a kernel panic[1],
therefore let's revert this commit.

[1] https://marc.info/?t=154965066400001&r=1&w=2

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/realtek/r8169.c b/drivers/net/ethernet/realtek/r8169.c
index bba806ce57d35dcd9f4f746d534a24a6cf32a873..6e36b88ca7c9c296fa5306e3376835f4259a7760 100644 (file)
--- a/drivers/net/ethernet/realtek/r8169.c
+++ b/drivers/net/ethernet/realtek/r8169.c
@@ -6074,7 +6074,6 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
        struct device *d = tp_to_dev(tp);
        dma_addr_t mapping;
        u32 opts[2], len;
-       bool stop_queue;
        int frags;
 
        if (unlikely(!rtl_tx_slots_avail(tp, skb_shinfo(skb)->nr_frags))) {
@@ -6116,6 +6115,8 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
 
        txd->opts2 = cpu_to_le32(opts[1]);
 
+       netdev_sent_queue(dev, skb->len);
+
        skb_tx_timestamp(skb);
 
        /* Force memory writes to complete before releasing descriptor */
@@ -6128,16 +6129,16 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
 
        tp->cur_tx += frags + 1;
 
-       stop_queue = !rtl_tx_slots_avail(tp, MAX_SKB_FRAGS);
-       if (unlikely(stop_queue))
-               netif_stop_queue(dev);
+       RTL_W8(tp, TxPoll, NPQ);
 
-       if (__netdev_sent_queue(dev, skb->len, skb->xmit_more)) {
-               RTL_W8(tp, TxPoll, NPQ);
-               mmiowb();
-       }
+       mmiowb();
 
-       if (unlikely(stop_queue)) {
+       if (!rtl_tx_slots_avail(tp, MAX_SKB_FRAGS)) {
+               /* Avoid wrongly optimistic queue wake-up: rtl_tx thread must
+                * not miss a ring update when it notices a stopped queue.
+                */
+               smp_wmb();
+               netif_stop_queue(dev);
                /* Sync with rtl_tx:
                 * - publish queue status and cur_tx ring index (write barrier)
                 * - refresh dirty_tx ring index (read barrier).