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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>
This commit is contained in:
Francois Romieu 2012-01-31 00:00:19 +01:00
parent aacafba8c2
commit ae1f23fb43
1 changed files with 18 additions and 0 deletions
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18
drivers/net/ethernet/realtek/r8169.c
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@ -5559,7 +5559,18 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
mmiowb(); mmiowb();
if (TX_BUFFS_AVAIL(tp) < MAX_SKB_FRAGS) { if (TX_BUFFS_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); 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).
* May the current thread have a pessimistic view of the ring
* status and forget to wake up queue, a racing rtl_tx thread
* can't.
*/
smp_mb(); smp_mb();
if (TX_BUFFS_AVAIL(tp) >= MAX_SKB_FRAGS) if (TX_BUFFS_AVAIL(tp) >= MAX_SKB_FRAGS)
netif_wake_queue(dev); netif_wake_queue(dev);
@ -5659,6 +5670,13 @@ static void rtl_tx(struct net_device *dev, struct rtl8169_private *tp)
if (tp->dirty_tx != dirty_tx) { if (tp->dirty_tx != dirty_tx) {
tp->dirty_tx = dirty_tx; tp->dirty_tx = dirty_tx;
/* Sync with rtl8169_start_xmit:
* - publish dirty_tx ring index (write barrier)
* - refresh cur_tx ring index and queue status (read barrier)
* May the current thread miss the stopped queue condition,
* a racing xmit thread can only have a right view of the
* ring status.
*/
smp_mb(); smp_mb();
if (netif_queue_stopped(dev) && if (netif_queue_stopped(dev) &&
(TX_BUFFS_AVAIL(tp) >= MAX_SKB_FRAGS)) { (TX_BUFFS_AVAIL(tp) >= MAX_SKB_FRAGS)) {