diff options
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 d039d39963ad..859554a03a09 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)) { |