diff options
| author | Francois Romieu <romieu@fr.zoreil.com> | 2012-01-31 00:00:19 +0100 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2012-06-10 14:42:04 +0100 |
| commit | ba3d9c0eb1ed88c156e49eadcb1e9ec22cfc2fed (patch) | |
| tree | 809d6bbcd3700a634e804fa4b05a3ea33ba4bb2c | |
| parent | 32244144e774f32db30e9f33df7b54e0cddfa475 (diff) | |
r8169: fix early queue wake-up.
[ Upstream commit ae1f23fb433ac0aaff8aeaa5a7b14348e9aa8277 ]
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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -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 5104d769e8f5..5f3fa3242c57 100644 --- a/drivers/net/ethernet/realtek/r8169.c +++ b/drivers/net/ethernet/realtek/r8169.c @@ -5561,7 +5561,18 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb, RTL_W8(TxPoll, NPQ); 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); @@ -5663,6 +5674,13 @@ static void rtl8169_tx_interrupt(struct net_device *dev, 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)) { |