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Minor improvement for smsc95xx netusb driver performance. #139

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Minor improvement for smsc95xx netusb driver performance. #139

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31 changes: 16 additions & 15 deletions drivers/net/usb/smsc95xx.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1833,7 +1833,9 @@ static struct sk_buff *smsc95xx_tx_fixup(struct usbnet *dev,
{
bool csum = skb->ip_summed == CHECKSUM_PARTIAL;
int overhead = csum ? SMSC95XX_TX_OVERHEAD_CSUM : SMSC95XX_TX_OVERHEAD;
u32 tx_cmd_a, tx_cmd_b;
struct tx_commands_t {
u32 cmd_a, cmd_b, csum_preamble;
}tx_cmds;

/* We do not advertise SG, so skbs should be already linearized */
BUG_ON(skb_shinfo(skb)->nr_frags);
Expand All @@ -1858,26 +1860,25 @@ static struct sk_buff *smsc95xx_tx_fixup(struct usbnet *dev,
+ skb->csum_offset)) = csum_fold(calc);

csum = false;
overhead = SMSC95XX_TX_OVERHEAD;
} else {
u32 csum_preamble = smsc95xx_calc_csum_preamble(skb);
tx_cmds.csum_preamble = smsc95xx_calc_csum_preamble(skb);
skb_push(skb, 4);
cpu_to_le32s(&csum_preamble);
memcpy(skb->data, &csum_preamble, 4);
cpu_to_le32s(&tx_cmds.csum_preamble);
}
}

skb_push(skb, 4);
tx_cmd_b = (u32)(skb->len - 4);
if (csum)
tx_cmd_b |= TX_CMD_B_CSUM_ENABLE;
cpu_to_le32s(&tx_cmd_b);
memcpy(skb->data, &tx_cmd_b, 4);

skb_push(skb, 4);
tx_cmd_a = (u32)(skb->len - 8) | TX_CMD_A_FIRST_SEG_ |
tx_cmds.cmd_a = (u32)(skb->len) | TX_CMD_A_FIRST_SEG_ |
TX_CMD_A_LAST_SEG_;
cpu_to_le32s(&tx_cmd_a);
memcpy(skb->data, &tx_cmd_a, 4);
cpu_to_le32s(&tx_cmds.cmd_a);

tx_cmds.cmd_b = (u32)(skb->len);
if (csum)
tx_cmds.cmd_b |= TX_CMD_B_CSUM_ENABLE;
cpu_to_le32s(&tx_cmds.cmd_b);

skb_push(skb, 8);
memcpy(skb->data, &tx_cmds, overhead);

return skb;
}
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