Re: [PATCH net v2] net: dsa: tag_rtl4_a: Bump min packet size
From: Linus Walleij
Date: Tue Oct 31 2023 - 17:22:27 EST
Hi Vladimir,
I got around to testing this too:
On Mon, Oct 30, 2023 at 4:31 PM Vladimir Oltean <olteanv@xxxxxxxxx> wrote:
> Could you please place these skb_dump() calls before and after the magic
> __skb_put_padto() call, for us to see if anything unexpected changes?
> Maybe the socket buffers have some unusual geometry which the conduit
> interface doesn't like, for some reason.
>
> The number of skb dumps that you provide back should be even, and
> ideally the first one should be the unaltered packet, to avoid confusion :)
I did a variant to just get one SKB dump and not tons of them;
@@ -37,22 +37,35 @@ static struct sk_buff *rtl4a_tag_xmit(struct sk_buff *skb,
struct net_device *dev)
{
struct dsa_port *dp = dsa_slave_to_port(dev);
+ static int cnt = 0;
__be16 *p;
u8 *tag;
u16 out;
- /* Pad out to at least 60 bytes */
- if (unlikely(__skb_put_padto(skb, ETH_ZLEN, false)))
- return NULL;
-
/* Packets over 1496 bytes get dropped unless they get padded
* out to 1518 bytes. 1496 is ETH_DATA_LEN - tag which is hardly
* a coinicidence, and 1518 is ETH_FRAME_LEN + FCS so we define
* the threshold size and padding like this.
*/
if (skb->len >= (ETH_DATA_LEN - RTL4_A_HDR_LEN)) {
+ cnt++;
+
+ if (cnt == 1) {
+ pr_info("SKB before padding:\n");
+ skb_dump(KERN_INFO, skb, true);
+ }
+
if (unlikely(__skb_put_padto(skb, ETH_FRAME_LEN +
ETH_FCS_LEN, false)))
return NULL;
+
+ if (cnt == 1) {
+ pr_info("SKB after padding:\n");
+ skb_dump(KERN_INFO, skb, true);
+ }
+ } else {
+ /* Pad out to at least 60 bytes */
+ if (unlikely(__skb_put_padto(skb, ETH_ZLEN, false)))
+ return NULL;
}
# ping -s 1472 192.168.1.137
The result:
SKB before padding:
37 (192.168.1.13skb len=1514 headroom=18 headlen=1514 tailroom=260
mac=(18,14) net=(32,20) trans=52
shinfo(txflags=0 nr_frags=0 gso(size=0 type=0 segs=0))
csum(0xd4ef2b1 ip_summed=0 complete_sw=0 valid=0 level=0)
hash(0x0 sw=0 l4=0) proto=0x0800 pkttype=0 iif=0
7): 1472 data bydev name=lan0 feat=0x0002000000005020
tes
sk family=2 type=3 proto=1
skb headroom: 00000000: 00 02 00 01 00 00 00 00 00 00 03 78 02 00 bc ae
skb headroom: 00000010: 00 00
skb linear: 00000000: bc ae c5 6b a8 3d c2 2f 0b dc cc b4 08 00 45 00
skb linear: 00000010: 05 dc 3b de 40 00 40 01 75 68 c0 a8 01 01 c0 a8
skb linear: 00000020: 01 89 08 00 16 d2 09 54 00 00 8a cc 4d 0d 00 00
skb linear: 00000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000090: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000000a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000000b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000000c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000000d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000000e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000000f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000110: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000120: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000130: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000140: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000150: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000160: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000170: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000190: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000001a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000001b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000001c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000001d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000001e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000001f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000210: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000220: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000230: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000240: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000250: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000260: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000270: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000290: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000002a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000002b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000002c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000002d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000002e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000002f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000310: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000320: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000330: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000340: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000350: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000360: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000370: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000390: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000003a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000003b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000003c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000003d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000003e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000003f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000410: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000420: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000430: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000440: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000450: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000460: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000470: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000490: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000004a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000004b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000004c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000004d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000004e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000004f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000510: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000520: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000530: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000540: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000550: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000560: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000570: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000590: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000005a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000005b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000005c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000005d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000005e0: 00 00 00 00 00 00 00 00 00 00
skb tailroom: 00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 00000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 00000040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 00000050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 00000060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 00000070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 00000080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 00000090: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 000000a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 000000b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 000000c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 000000d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 000000e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 000000f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 00000100: 00 00 00 00
SKB after padding:
skb len=1518 headroom=18 headlen=1518 tailroom=256
mac=(18,14) net=(32,20) trans=52
shinfo(txflags=0 nr_frags=0 gso(size=0 type=0 segs=0))
csum(0xd4ef2b1 ip_summed=0 complete_sw=0 valid=0 level=0)
hash(0x0 sw=0 l4=0) proto=0x0800 pkttype=0 iif=0
dev name=lan0 feat=0x0002000000005020
sk family=2 type=3 proto=1
skb headroom: 00000000: 00 02 00 01 00 00 00 00 00 00 03 78 02 00 bc ae
skb headroom: 00000010: 00 00
skb linear: 00000000: bc ae c5 6b a8 3d c2 2f 0b dc cc b4 08 00 45 00
skb linear: 00000010: 05 dc 3b de 40 00 40 01 75 68 c0 a8 01 01 c0 a8
skb linear: 00000020: 01 89 08 00 16 d2 09 54 00 00 8a cc 4d 0d 00 00
skb linear: 00000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000090: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000000a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000000b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000000c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000000d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000000e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000000f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000110: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000120: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000130: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000140: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000150: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000160: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000170: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000190: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000001a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000001b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000001c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000001d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000001e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000001f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000210: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000220: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000230: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000240: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000250: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000260: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000270: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000290: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000002a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000002b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000002c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000002d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000002e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000002f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000310: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000320: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000330: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000340: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000350: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000360: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000370: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000390: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000003a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000003b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000003c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000003d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000003e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000003f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000410: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000420: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000430: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000440: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000450: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000460: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000470: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000490: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000004a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000004b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000004c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000004d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000004e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000004f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000510: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000520: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000530: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000540: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000550: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000560: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000570: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 00000590: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000005a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000005b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000005c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000005d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb linear: 000005e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 00000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 00000040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 00000050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 00000060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 00000070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 00000080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 00000090: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 000000a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 000000b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 000000c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 000000d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 000000e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
skb tailroom: 000000f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
As expected the linear SKB is 4 bytes longer in this case.
Yours,
Linus Walleij