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Date: Wed, 14 Mar 2012 23:18:32 -0700
From: Eric Dumazet <eric.dumazet@...il.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
David Miller <davem@...emloft.net>
Cc: linux-usb@...r.kernel.org, netdev <netdev@...r.kernel.org>,
Aurelien Jacobs <aurel@...age.org>,
Trond Wuellner <trond@...omium.org>,
Grant Grundler <grundler@...omium.org>,
Paul Stewart <pstew@...omium.org>
Subject: [PATCH net-next] 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@...il.com>
Cc: Aurelien Jacobs <aurel@...age.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Trond Wuellner <trond@...omium.org>
Cc: Grant Grundler <grundler@...omium.org>
Cc: Paul Stewart <pstew@...omium.org>
---
drivers/net/usb/asix.c | 90 +++++++++------------------------------
1 file changed, 21 insertions(+), 69 deletions(-)
diff --git a/drivers/net/usb/asix.c b/drivers/net/usb/asix.c
index 8e84f5b..27d5440 100644
--- a/drivers/net/usb/asix.c
+++ b/drivers/net/usb/asix.c
@@ -305,88 +305,40 @@ asix_write_cmd_async(struct usbnet *dev, u8 cmd, u16 value, u16 index,
static int asix_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
{
- u8 *head;
- u32 header;
- char *packet;
- struct sk_buff *ax_skb;
- u16 size;
+ int offset = 0;
- head = (u8 *) skb->data;
- memcpy(&header, head, sizeof(header));
- le32_to_cpus(&header);
- packet = head + sizeof(header);
-
- skb_pull(skb, 4);
-
- while (skb->len > 0) {
- if ((header & 0x07ff) != ((~header >> 16) & 0x07ff))
- netdev_err(dev->net, "asix_rx_fixup() Bad Header Length\n");
+ while (offset + sizeof(u32) < skb->len) {
+ struct sk_buff *ax_skb;
+ u16 size;
+ u32 header = get_unaligned_le32(skb->data + offset);
+ offset += sizeof(u32);
+
/* get the packet length */
- size = (u16) (header & 0x000007ff);
-
- if ((skb->len) - ((size + 1) & 0xfffe) == 0) {
- u8 alignment = (unsigned long)skb->data & 0x3;
- if (alignment != 0x2) {
- /*
- * not 16bit aligned so use the room provided by
- * the 32 bit header to align the data
- *
- * note we want 16bit alignment as MAC header is
- * 14bytes thus ip header will be aligned on
- * 32bit boundary so accessing ipheader elements
- * using a cast to struct ip header wont cause
- * an unaligned accesses.
- */
- u8 realignment = (alignment + 2) & 0x3;
- memmove(skb->data - realignment,
- skb->data,
- size);
- skb->data -= realignment;
- skb_set_tail_pointer(skb, size);
- }
- return 2;
+ size = (u16) (header & 0x7ff);
+ if (size != ((~header >> 16) & 0x07ff)) {
+ netdev_err(dev->net, "asix_rx_fixup() Bad Header Length\n");
+ return 0;
}
- if (size > dev->net->mtu + ETH_HLEN) {
+ if ((size > dev->net->mtu + ETH_HLEN) ||
+ (size + offset > skb->len)) {
netdev_err(dev->net, "asix_rx_fixup() Bad RX Length %d\n",
size);
return 0;
}
- ax_skb = skb_clone(skb, GFP_ATOMIC);
- if (ax_skb) {
- u8 alignment = (unsigned long)packet & 0x3;
- ax_skb->len = size;
-
- if (alignment != 0x2) {
- /*
- * not 16bit aligned use the room provided by
- * the 32 bit header to align the data
- */
- u8 realignment = (alignment + 2) & 0x3;
- memmove(packet - realignment, packet, size);
- packet -= realignment;
- }
- ax_skb->data = packet;
- skb_set_tail_pointer(ax_skb, size);
- usbnet_skb_return(dev, ax_skb);
- } else {
+ ax_skb = netdev_alloc_skb_ip_align(dev->net, size);
+ if (!ax_skb)
return 0;
- }
-
- skb_pull(skb, (size + 1) & 0xfffe);
- if (skb->len < sizeof(header))
- break;
+ skb_put(ax_skb, size);
+ memcpy(ax_skb->data, skb->data + offset, size);
+ usbnet_skb_return(dev, ax_skb);
- head = (u8 *) skb->data;
- memcpy(&header, head, sizeof(header));
- le32_to_cpus(&header);
- packet = head + sizeof(header);
- skb_pull(skb, 4);
+ offset += (size + 1) & 0xfffe;
}
- if (skb->len < 0) {
+ if (skb->len != offset) {
netdev_err(dev->net, "asix_rx_fixup() Bad SKB Length %d\n",
skb->len);
return 0;
@@ -1541,7 +1493,7 @@ static const struct driver_info ax88772_info = {
.status = asix_status,
.link_reset = ax88772_link_reset,
.reset = ax88772_reset,
- .flags = FLAG_ETHER | FLAG_FRAMING_AX | FLAG_LINK_INTR,
+ .flags = FLAG_ETHER | FLAG_FRAMING_AX | FLAG_LINK_INTR | FLAG_MULTI_PACKET,
.rx_fixup = asix_rx_fixup,
.tx_fixup = asix_tx_fixup,
};
--
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