asix: asix_rx_fixup surgery to reduce skb truesizes
asix_rx_fixup() is complex, and does some unnecessary memory copies (at least on x86 where NET_IP_ALIGN is 0) Also, it tends to provide skbs with a big truesize (4096+256 with MTU=1500) to upper stack, so incoming trafic consume a lot of memory and I noticed early packet drops because we hit socket rcvbuf too fast. Switch to a different strategy, using copybreak so that we provide nice skbs to upper stack (including the NET_SKB_PAD to avoid future head reallocations in some paths) With this patch, I no longer see packets drops or tcp collapses on various tcp workload with a AX88772 adapter. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Cc: Aurelien Jacobs <aurel@gnuage.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Trond Wuellner <trond@chromium.org> Cc: Grant Grundler <grundler@chromium.org> Cc: Paul Stewart <pstew@chromium.org> Reviewed-by: Grant Grundler <grundler@chromium.org> Reviewed-by: Grant Grundler <grundler@chromium.org> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -305,88 +305,40 @@ asix_write_cmd_async(struct usbnet *dev, u8 cmd, u16 value, u16 index,
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static int asix_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
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{
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u8 *head;
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u32 header;
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char *packet;
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int offset = 0;
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while (offset + sizeof(u32) < skb->len) {
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struct sk_buff *ax_skb;
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u16 size;
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u32 header = get_unaligned_le32(skb->data + offset);
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head = (u8 *) skb->data;
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memcpy(&header, head, sizeof(header));
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le32_to_cpus(&header);
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packet = head + sizeof(header);
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skb_pull(skb, 4);
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while (skb->len > 0) {
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if ((header & 0x07ff) != ((~header >> 16) & 0x07ff))
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netdev_err(dev->net, "asix_rx_fixup() Bad Header Length\n");
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offset += sizeof(u32);
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/* get the packet length */
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size = (u16) (header & 0x000007ff);
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if ((skb->len) - ((size + 1) & 0xfffe) == 0) {
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u8 alignment = (unsigned long)skb->data & 0x3;
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if (alignment != 0x2) {
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/*
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* not 16bit aligned so use the room provided by
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* the 32 bit header to align the data
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*
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* note we want 16bit alignment as MAC header is
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* 14bytes thus ip header will be aligned on
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* 32bit boundary so accessing ipheader elements
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* using a cast to struct ip header wont cause
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* an unaligned accesses.
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*/
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u8 realignment = (alignment + 2) & 0x3;
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memmove(skb->data - realignment,
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skb->data,
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size);
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skb->data -= realignment;
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skb_set_tail_pointer(skb, size);
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}
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return 2;
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size = (u16) (header & 0x7ff);
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if (size != ((~header >> 16) & 0x07ff)) {
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netdev_err(dev->net, "asix_rx_fixup() Bad Header Length\n");
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return 0;
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}
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if (size > dev->net->mtu + ETH_HLEN) {
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if ((size > dev->net->mtu + ETH_HLEN) ||
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(size + offset > skb->len)) {
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netdev_err(dev->net, "asix_rx_fixup() Bad RX Length %d\n",
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size);
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return 0;
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}
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ax_skb = skb_clone(skb, GFP_ATOMIC);
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if (ax_skb) {
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u8 alignment = (unsigned long)packet & 0x3;
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ax_skb->len = size;
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if (alignment != 0x2) {
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/*
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* not 16bit aligned use the room provided by
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* the 32 bit header to align the data
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*/
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u8 realignment = (alignment + 2) & 0x3;
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memmove(packet - realignment, packet, size);
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packet -= realignment;
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}
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ax_skb->data = packet;
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skb_set_tail_pointer(ax_skb, size);
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usbnet_skb_return(dev, ax_skb);
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} else {
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ax_skb = netdev_alloc_skb_ip_align(dev->net, size);
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if (!ax_skb)
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return 0;
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skb_put(ax_skb, size);
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memcpy(ax_skb->data, skb->data + offset, size);
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usbnet_skb_return(dev, ax_skb);
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offset += (size + 1) & 0xfffe;
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}
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skb_pull(skb, (size + 1) & 0xfffe);
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if (skb->len < sizeof(header))
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break;
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head = (u8 *) skb->data;
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memcpy(&header, head, sizeof(header));
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le32_to_cpus(&header);
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packet = head + sizeof(header);
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skb_pull(skb, 4);
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}
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if (skb->len < 0) {
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if (skb->len != offset) {
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netdev_err(dev->net, "asix_rx_fixup() Bad SKB Length %d\n",
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skb->len);
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return 0;
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@ -1541,7 +1493,7 @@ static const struct driver_info ax88772_info = {
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.status = asix_status,
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.link_reset = ax88772_link_reset,
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.reset = ax88772_reset,
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.flags = FLAG_ETHER | FLAG_FRAMING_AX | FLAG_LINK_INTR,
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.flags = FLAG_ETHER | FLAG_FRAMING_AX | FLAG_LINK_INTR | FLAG_MULTI_PACKET,
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.rx_fixup = asix_rx_fixup,
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.tx_fixup = asix_tx_fixup,
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};
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