Gianfar skb panic when bonding a VLAN interface

Gianfar skb panic when bonding a VLAN interface

[Demke Torsten-atd012]

Hi,

I tried to ping over a bonded VLAN tagged interface.
(e.g  -> ifenslave bond0 eth3.24)

This fails with following output:
root@myBoard:/root> ping 192.168.24.101
PING 192.168.24.skb_under_panic: text:c01bbdf8 len:50 put:8
head:dd27a3a0 data:dd27a39a tail:dd27a3cc end:dd27a3e0 dev:eth3
Oops: Exception in kernel mode, sig: 5 [#1]
NIP: C01E9110 LR: C01E9110 SP: C03479F0 REGS: c0347940 TRAP: 0700
Tainted: PF   =20
MSR: 00021000 EE: 0 PR: 0 FP: 0 ME: 1 IR/DR: 00
TASK =3D c03031a0[0] 'swapper' THREAD: c0346000
Last syscall: 120=20
GPR00: C01E9110 C03479F0 C03031A0 00000072 00002D03 FFFFFFFF 00000030
00003FFF=20
GPR08: C037D0AC C0340000 FFFFFFFF 00000000 65F51C00 60000000 0FFE3900
C0347A7C=20
GPR16: DFC1FD60 C0347DD0 C0B94800 0FFF3D0C C0347A80 00000000 007FD890
00000000=20
GPR24: 00000000 C0A81865 C0A81805 00000000 C0B94800 DFC1FD60 C0B94A40
DF10C128=20
NIP [c01e9110] skb_under_panic+0x50/0x64
LR [c01e9110] skb_under_panic+0x50/0x64
Call trace:
 [c01bbe0c] gfar_add_fcb+0x7c/0xb4
 [c01bbfc0] gfar_start_xmit+0x160/0x268
 [c01ffffc] qdisc_restart+0x100/0x1fc
 [c01f04c4] dev_queue_xmit+0xc88/0xde0
 [c02a9684] vlan_dev_hwaccel_hard_start_xmit+0x9c/0xb0
 [c01f054c] dev_queue_xmit+0xd10/0xde0
 [c01afaa8] bond_dev_queue_xmit+0x2a8/0x2c4
 [c01b4464] bond_xmit_roundrobin+0x94/0x108
 [c01f054c] dev_queue_xmit+0xd10/0xde0
 [c022f6cc] arp_xmit+0x5c/0x6c
 [c022f704] arp_send+0x28/0x38
 [c022ef48] arp_solicit+0x1a0/0x1c0
 [c01f81b0] neigh_timer_handler+0x294/0x31c
 [c0043310] run_timer_softirq+0xa7c/0xaec
 [c0039b68] __do_softirq+0xabc/0x15a0
101 (192.168.24.Kernel panic - not syncing: Aiee, killing interrupt
handler!
101) 56(84) byte s of data.
Call trace:
 [c0008258] dump_stack+0x18/0x28
 [c002fa50] panic+0xa8/0x190
 [c0033690] do_exit+0x3c/0xdec
 [c0002fb4] _exception+0x0/0x1558
 [c0002ff0] _exception+0x3c/0x1558
 [c0004d70] ProgramCheckException+0x11c/0x1c4
 [c00029ac] ret_from_except_full+0x0/0x4c
 [c01e9110] skb_under_panic+0x50/0x64
 [c01bbe0c] gfar_add_fcb+0x7c/0xb4
 [c01bbfc0] gfar_start_xmit+0x160/0x268
 [c01ffffc] qdisc_restart+0x100/0x1fc
 [c01f04c4] dev_queue_xmit+0xc88/0xde0
 [c02a9684] vlan_dev_hwaccel_hard_start_xmit+0x9c/0xb0
 [c01f054c] dev_queue_xmit+0xd10/0xde0
 [c01afaa8] bond_dev_queue_xmit+0x2a8/0x2c4
Rebooting in 180 seconds..

It seems that the skb headroom is to small. How can I solve this?
I could insert skb_realloc_headroom() call, but where it's the best
place then?
What about alignement?


Regards,
Torsten

Re: Gianfar skb panic when bonding a VLAN interface

[Jay Vosburgh]

Demke Torsten-atd012 <torsten.demke@motorola.com> wrote:

>I tried to ping over a bonded VLAN tagged interface.
>(e.g  -> ifenslave bond0 eth3.24)
[...]
>It seems that the skb headroom is to small. How can I solve this?
>I could insert skb_realloc_headroom() call, but where it's the best
>place then?
>What about alignement?

	What kernel are you using?  There was a fix applied to the
bonding driver about a year ago to resolve this problem with gianfar:

commit 54ef313714070b397d3857289f0fd099b7643631
Author: Jay Vosburgh <fubar@us.ibm.com>
Date:   Fri Sep 22 21:53:39 2006 -0700

    [PATCH] bonding: Handle large hard_header_len
    
    The bonding driver fails to adjust its hard_header_len when enslaving
    interfaces.  Whenever an interface with a hard_header_len greater than the
    ETH_HLEN default is enslaved, the potential for an oops exists, and if the
    oops happens while responding to an arp request, for example, the system
    panics.  GIANFAR devices may use an extended hard_header for VLAN or
    hardware checksumming.  Enslaving such a device and then transmitting over
    it causes a kernel panic.
    
    Patch modified from submitter's original, but submitter agreed with this
    patch in private email.
    
    Signed-off-by: Mark Huth <mhuth@mvista.com>
    Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>
    Signed-off-by: Jeff Garzik <jeff@garzik.org>

	-J

---
	-Jay Vosburgh, IBM Linux Technology Center, fubar@us.ibm.com