Re: [RFC] r8169 : why SG / TX checksum are default disabled
From: Francois Romieu <romieu@fr.zoreil.com>
Date: 2012-07-20 10:21:44
Subsystem:
8169 10/100/1000 gigabit ethernet driver, networking drivers, the rest · Maintainers:
Heiner Kallweit, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
hayeswang [off-list ref] : [...]
I find that the total length field of IP header would be modified if the hw checksum is enabled. Therefore, skb_padto + hw checksum wouldn't work.
Ok, my patch completely ignored the fact that skb_padto does not change the length. However skb_padto + length adjustement + hw checksum should work (at least in theory if not in the patch below) ?
diff --git a/drivers/net/ethernet/realtek/r8169.c b/drivers/net/ethernet/realtek/r8169.c
index be4e00f..8d0cc09 100644
--- a/drivers/net/ethernet/realtek/r8169.c
+++ b/drivers/net/ethernet/realtek/r8169.c@@ -5740,7 +5740,7 @@ err_out: return -EIO; } -static inline void rtl8169_tso_csum(struct rtl8169_private *tp, +static inline bool rtl8169_tso_csum(struct rtl8169_private *tp, struct sk_buff *skb, u32 *opts) { const struct rtl_tx_desc_info *info = tx_desc_info + tp->txd_version;
@@ -5753,6 +5753,13 @@ static inline void rtl8169_tso_csum(struct rtl8169_private *tp, } else if (skb->ip_summed == CHECKSUM_PARTIAL) { const struct iphdr *ip = ip_hdr(skb); + if (unlikely(skb->len < ETH_ZLEN && + (tp->mac_version == RTL_GIGA_MAC_VER_34))) { + if (skb_padto(skb, ETH_ZLEN)) + return false; + skb_put(skb, ETH_ZLEN - skb->len); + } + if (ip->protocol == IPPROTO_TCP) opts[offset] |= info->checksum.tcp; else if (ip->protocol == IPPROTO_UDP)
@@ -5760,6 +5767,7 @@ static inline void rtl8169_tso_csum(struct rtl8169_private *tp, else WARN_ON_ONCE(1); } + return true; } static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
@@ -5783,25 +5791,26 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb, if (unlikely(le32_to_cpu(txd->opts1) & DescOwn)) goto err_stop_0; + opts[1] = cpu_to_le32(rtl8169_tx_vlan_tag(tp, skb)); + opts[0] = DescOwn; + + if (!rtl8169_tso_csum(tp, skb, opts)) + goto err_update_stats_0; + len = skb_headlen(skb); mapping = dma_map_single(d, skb->data, len, DMA_TO_DEVICE); if (unlikely(dma_mapping_error(d, mapping))) { if (net_ratelimit()) netif_err(tp, drv, dev, "Failed to map TX DMA!\n"); - goto err_dma_0; + goto err_free_skb_1; } tp->tx_skb[entry].len = len; txd->addr = cpu_to_le64(mapping); - opts[1] = cpu_to_le32(rtl8169_tx_vlan_tag(tp, skb)); - opts[0] = DescOwn; - - rtl8169_tso_csum(tp, skb, opts); - frags = rtl8169_xmit_frags(tp, skb, opts); if (frags < 0) - goto err_dma_1; + goto err_unmap_2; else if (frags) opts[0] |= FirstFrag; else {
@@ -5849,10 +5858,11 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb, return NETDEV_TX_OK; -err_dma_1: +err_unmap_2: rtl8169_unmap_tx_skb(d, tp->tx_skb + entry, txd); -err_dma_0: +err_free_skb_1: dev_kfree_skb(skb); +err_update_stats_0: dev->stats.tx_dropped++; return NETDEV_TX_OK;