diff options
| author | Heiner Kallweit <hkallweit1@gmail.com> | 2020-11-14 21:49:53 +0100 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2020-11-16 07:54:07 -0800 |
| commit | 41294e6a434d4f19e957c55b275ea0324f275009 (patch) | |
| tree | 518242e3dcf467be259832e50b63b9cc2822ccd5 | |
| parent | 0064c5c1b3bf2a695c772c90e8dea38426a870ff (diff) | |
r8169: improve rtl8169_start_xmit
Improve the following in rtl8169_start_xmit:
- tp->cur_tx can be accessed in parallel by rtl_tx(), therefore
annotate the race by using WRITE_ONCE
- avoid checking stop_queue a second time by moving the doorbell check
- netif_stop_queue() uses atomic operation set_bit() that includes a
full memory barrier on some platforms, therefore use
smp_mb__after_atomic to avoid overhead
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://lore.kernel.org/r/80085451-3eaf-507a-c7c0-08d607c46fbc@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | drivers/net/ethernet/realtek/r8169_main.c | 15 |
1 files changed, 6 insertions, 9 deletions
diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c index 8910e900ec45..940fc6590566 100644 --- a/drivers/net/ethernet/realtek/r8169_main.c +++ b/drivers/net/ethernet/realtek/r8169_main.c @@ -4226,7 +4226,7 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb, /* rtl_tx needs to see descriptor changes before updated tp->cur_tx */ smp_wmb(); - tp->cur_tx += frags + 1; + WRITE_ONCE(tp->cur_tx, tp->cur_tx + frags + 1); stop_queue = !rtl_tx_slots_avail(tp, MAX_SKB_FRAGS); if (unlikely(stop_queue)) { @@ -4235,13 +4235,6 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb, */ smp_wmb(); netif_stop_queue(dev); - door_bell = true; - } - - if (door_bell) - rtl8169_doorbell(tp); - - if (unlikely(stop_queue)) { /* Sync with rtl_tx: * - publish queue status and cur_tx ring index (write barrier) * - refresh dirty_tx ring index (read barrier). @@ -4249,11 +4242,15 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb, * status and forget to wake up queue, a racing rtl_tx thread * can't. */ - smp_mb(); + smp_mb__after_atomic(); if (rtl_tx_slots_avail(tp, MAX_SKB_FRAGS)) netif_start_queue(dev); + door_bell = true; } + if (door_bell) + rtl8169_doorbell(tp); + return NETDEV_TX_OK; err_dma_1: |