Could the problem be that the e100 can do IP receive checksumming on the board,
but the eepro driver doesn't enable it. When the board is doing checksum
offload, then the csum field isn't set.
Please try disabling receive checksumming on the e100 driver
modprobe e100 XsumRX=0
If this is the problem, it exists both 2.4 and 2.6.
Indeed: with XsumRX=0,0 the BUG doesn't happen. I put some debugging code in dev.c:
=== CUT HERE ===
--- dev.c.orig 2003-08-28 20:00:22.000000000 +0200
+++ dev.c 2003-08-28 20:59:19.000000000 +0200
@@ -987,9 +987,29 @@
offset = skb->tail - skb->h.raw;
if (offset <= 0)
BUG();
- if (skb->csum+2 > offset)
+/* if (skb->csum+2 > offset)
BUG();
-
+*/
+ if (skb->csum+2 > offset) {
+ printk (KERN_EMERG "skb->csum+2=%d, offset=%d, skb->ip_summed=%d\n", skb->csum+2, offset, (int)(skb->ip_summed));
+ printk (KERN_EMERG "skb->mac.ethernet->h_dest=%0.2x:%0.2x:%0.2x:%0.2x:%0.2x:%0.2x\n",
+ (unsigned int)(skb->mac.ethernet->h_dest [0]),
+ (unsigned int)(skb->mac.ethernet->h_dest [1]),
+ (unsigned int)(skb->mac.ethernet->h_dest [2]),
+ (unsigned int)(skb->mac.ethernet->h_dest [3]),
+ (unsigned int)(skb->mac.ethernet->h_dest [4]),
+ (unsigned int)(skb->mac.ethernet->h_dest [5])
+ );
+ printk (KERN_EMERG "skb->mac.ethernet->h_source=%0.2x:%0.2x:%0.2x:%0.2x:%0.2x:%0.2x\n",
+ (unsigned int)(skb->mac.ethernet->h_source [0]),
+ (unsigned int)(skb->mac.ethernet->h_source [1]),
+ (unsigned int)(skb->mac.ethernet->h_source [2]),
+ (unsigned int)(skb->mac.ethernet->h_source [3]),
+ (unsigned int)(skb->mac.ethernet->h_source [4]),
+ (unsigned int)(skb->mac.ethernet->h_source [5])
+ );
+ BUG ();
+ }
*(u16*)(skb->h.raw + skb->csum) = csum_fold(csum);
skb->ip_summed = CHECKSUM_NONE;
return skb;
=== CUT HERE ===
It says (just before the BUG): skb->csum+2=33323, offset=168, skb->ip_summed=1 skb->mac.ethernet->h_dest=ff:ff:ff:ff:ff:ff skb->mac.ethernet->h_source=00:d0:b7:3c:78:0a
I also put a few lines in e100_main.c:
=== CUT HERE ===
--- e100_main.c.orig 2003-08-28 21:01:07.000000000 +0200
+++ e100_main.c 2003-08-28 21:07:10.000000000 +0200
@@ -2051,11 +2051,14 @@
if (bdp->flags & DF_CSUM_OFFLOAD) {
if (bdp->rev_id >= D102_REV_ID) {
skb->ip_summed = e100_D102_check_checksum(rfd);
+ printk (KERN_ERR "e100_D102: skb->csum+2=%d,offset=%d, skb->ip_summed=%d\n", skb->csum+2, skb->tail - skb->h.raw, (int)(skb->ip_summed));
} else {
skb->ip_summed = e100_D101M_checksum(bdp, skb);
+ printk (KERN_ERR "e100_D101M: skb->csum+2=%d,offset=%d, skb->ip_summed=%d\n", skb->csum+2, skb->tail - skb->h.raw, (int)(skb->ip_summed));
}
} else {
skb->ip_summed = CHECKSUM_NONE;
+ printk (KERN_ERR "e100_NOOFF: skb->csum+2=%d,offset=%d, skb->ip_summed=%d\n", skb->csum+2, skb->tail - skb->h.raw, (int)(skb->ip_summed));
}
bdp->drv_stats.net_stats.rx_bytes += skb->len; === CUT HERE ===
and my console was flooded with these:
e100_D101M: skb->csum+2=47564,offset=-2789414, skb->ip_summed=1
e100_D101M: skb->csum+2=38865,offset=3991018, skb->ip_summed=0
e100_D101M: skb->csum+2=33998,offset=4009612, skb->ip_summed=1
e100_D101M: skb->csum+2=11471,offset=845290, skb->ip_summed=1
e100_D101M: skb->csum+2=33323,offset=4036692, skb->ip_summed=1
^^^^^
this line was printed just above the BUG. The bug itself is essentially the same as before; just different offsets.
I think the packet in question is a broadcast of linux-ha sent out by a completely unrelated machine that happens to be on the same network:
uml:/usr/src/linux/drivers/net/e100# tcpdump -i br0 -e -n -q ether host 00:d0:b7:3c:78:0a
tcpdump: listening on br0
22:11:40.413171 0:d0:b7:3c:78:a ff:ff:ff:ff:ff:ff 182: 10.96.96.25.1025 > 10.96.96.255.694: udp 140
22:11:42.413154 0:d0:b7:3c:78:a ff:ff:ff:ff:ff:ff 182: 10.96.96.25.1025 > 10.96.96.255.694: udp 140
[and so on; the machine is idle at that time of the day]
Q: the 'offset' looks wrong in my code in e100_main.c [I didn't further investigate this]; but the skb->csum shows strong coincidence. What is happening here ?
Thanks in advance
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