| Message ID | 80085451-3eaf-507a-c7c0-08d607c46fbc@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net-next] r8169: improve rtl8169_start_xmit | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Clearly marked for net-next |
| netdev/subject_prefix | success | Link |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 0 this patch: 0 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | warning | WARNING: memory barrier without comment |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 0 this patch: 0 |
| netdev/header_inline | success | Link |
| netdev/stable | success | Stable not CCed |
On Sat, 14 Nov 2020 21:49:53 +0100 Heiner Kallweit wrote: > 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> Applied, thanks.
diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c index 8910e900e..940fc6590 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:
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> --- drivers/net/ethernet/realtek/r8169_main.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-)