diff options
| author | Francois Romieu <romieu@fr.zoreil.com> | 2012-01-31 00:00:19 +0100 |
|---|---|---|
| committer | Francois Romieu <romieu@fr.zoreil.com> | 2012-01-31 14:32:36 +0100 |
| commit | ae1f23fb433ac0aaff8aeaa5a7b14348e9aa8277 (patch) | |
| tree | d6ab98d10072c51005ea8691b773c33bdb6150df /drivers | |
| parent | aacafba8c2f4e9c9f3f38c60be83b65e69866723 (diff) | |
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>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/net/ethernet/realtek/r8169.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/drivers/net/ethernet/realtek/r8169.c b/drivers/net/ethernet/realtek/r8169.c index d039d39963a..859554a03a0 100644 --- a/drivers/net/ethernet/realtek/r8169.c +++ b/drivers/net/ethernet/realtek/r8169.c @@ -5559,7 +5559,18 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb, mmiowb(); 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); + /* 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(); if (TX_BUFFS_AVAIL(tp) >= MAX_SKB_FRAGS) 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) { 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(); if (netif_queue_stopped(dev) && (TX_BUFFS_AVAIL(tp) >= MAX_SKB_FRAGS)) { |