From 653e92a9175ea7ed67efe209c725222051a3713d Mon Sep 17 00:00:00 2001 From: Claudiu Beznea Date: Tue, 7 Aug 2018 12:25:14 +0300 Subject: [PATCH] net: macb: add support for padding and fcs computation For packets with computed IP/TCP/UDP checksum there is no need to tell hardware to recompute it. For such kind of packets hardware expects the packet to be at least 64 bytes and FCS to be computed. Signed-off-by: Claudiu Beznea Signed-off-by: David S. Miller --- drivers/net/ethernet/cadence/macb_main.c | 70 ++++++++++++++++++++++++ 1 file changed, 70 insertions(+) diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c index 332b19c645b4..dc09f9a8a49b 100644 --- a/drivers/net/ethernet/cadence/macb_main.c +++ b/drivers/net/ethernet/cadence/macb_main.c @@ -10,6 +10,7 @@ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include +#include #include #include #include @@ -1565,6 +1566,9 @@ static unsigned int macb_tx_map(struct macb *bp, if (i == queue->tx_head) { ctrl |= MACB_BF(TX_LSO, lso_ctrl); ctrl |= MACB_BF(TX_TCP_SEQ_SRC, seq_ctrl); + if ((bp->dev->features & NETIF_F_HW_CSUM) && + skb->ip_summed != CHECKSUM_PARTIAL && !lso_ctrl) + ctrl |= MACB_BIT(TX_NOCRC); } else /* Only set MSS/MFS on payload descriptors * (second or later descriptor) @@ -1651,6 +1655,67 @@ static inline int macb_clear_csum(struct sk_buff *skb) return 0; } +static int macb_pad_and_fcs(struct sk_buff **skb, struct net_device *ndev) +{ + bool cloned = skb_cloned(*skb) || skb_header_cloned(*skb); + int padlen = ETH_ZLEN - (*skb)->len; + int headroom = skb_headroom(*skb); + int tailroom = skb_tailroom(*skb); + struct sk_buff *nskb; + u32 fcs; + + if (!(ndev->features & NETIF_F_HW_CSUM) || + !((*skb)->ip_summed != CHECKSUM_PARTIAL) || + skb_shinfo(*skb)->gso_size) /* Not available for GSO */ + return 0; + + if (padlen <= 0) { + /* FCS could be appeded to tailroom. */ + if (tailroom >= ETH_FCS_LEN) + goto add_fcs; + /* FCS could be appeded by moving data to headroom. */ + else if (!cloned && headroom + tailroom >= ETH_FCS_LEN) + padlen = 0; + /* No room for FCS, need to reallocate skb. */ + else + padlen = ETH_FCS_LEN - tailroom; + } else { + /* Add room for FCS. */ + padlen += ETH_FCS_LEN; + } + + if (!cloned && headroom + tailroom >= padlen) { + (*skb)->data = memmove((*skb)->head, (*skb)->data, (*skb)->len); + skb_set_tail_pointer(*skb, (*skb)->len); + } else { + nskb = skb_copy_expand(*skb, 0, padlen, GFP_ATOMIC); + if (!nskb) + return -ENOMEM; + + dev_kfree_skb_any(*skb); + *skb = nskb; + } + + if (padlen) { + if (padlen >= ETH_FCS_LEN) + skb_put_zero(*skb, padlen - ETH_FCS_LEN); + else + skb_trim(*skb, ETH_FCS_LEN - padlen); + } + +add_fcs: + /* set FCS to packet */ + fcs = crc32_le(~0, (*skb)->data, (*skb)->len); + fcs = ~fcs; + + skb_put_u8(*skb, fcs & 0xff); + skb_put_u8(*skb, (fcs >> 8) & 0xff); + skb_put_u8(*skb, (fcs >> 16) & 0xff); + skb_put_u8(*skb, (fcs >> 24) & 0xff); + + return 0; +} + static netdev_tx_t macb_start_xmit(struct sk_buff *skb, struct net_device *dev) { u16 queue_index = skb_get_queue_mapping(skb); @@ -1667,6 +1732,11 @@ static netdev_tx_t macb_start_xmit(struct sk_buff *skb, struct net_device *dev) return ret; } + if (macb_pad_and_fcs(&skb, dev)) { + dev_kfree_skb_any(skb); + return ret; + } + is_lso = (skb_shinfo(skb)->gso_size != 0); if (is_lso) { -- 2.30.2