[Tipc-discussion] Re: status of UDP

[Jon M. <jon...@er...>]

Hi Mark,
I have not tested TIPC/UDP it on 2.6 at all; last time I did it was
with 2.4 on Vmware, not on SMP hardware. There it worked fine,
but evidently something has changed in the kernel since then.

I have a feeling that we are fighting losing battle here, trying
to use UDP in a way not anticipated in the Linux implementation.
I also got the feedback from IETF a few months ago that UDP was
very undesired as a carrier of TIPC, because it can be used over
the Internet in an uncontrollable way, without the inherent flow control
they want to se in all internet protocols. (Basically, I think they
would like to kill UDP as a protocol altogether, if they could.)

If you somhow can find an easy workaround for the problem you
see, it is ok to do it, otherwise I don't think we should spend much time
on it. We should rather remove it completely for now, and at some later
moment concentrate our effort to carry TIPC over TCP or SCTP.

What I have in mind is that we introduce a generic media
adaptation that only has the task of conveying sent/received packets
to/from a TIPC deamon in user space. It could be this daemon's task
to set up connections and transport the packets from node to node,
ensure encryption etc.
Performance would of course suffer, but for Internet protocols execution
time in the stack is not the dominating factor anyway.
For transporting packages to/from such a deamon we can use ioctl,
Netlink, or, why not, TIPC itself.

But these are future visions, I think.

Regards /Jon


Mark Haverkamp wrote:

>Jon,
>
>What is the status of TIPC UDP?  Has it been tested very much?  I tried
>loading tipc with UDP today and got lots of debug stack traces.
>
>For instance I loaded tipc with:
>
>insmod ./tipc.ko udp0=1 node=17 netid=1000
>
>And started seeing these:
>
>TIPC:  Compiled May 26 2004 07:29:42
>TIPC:  Own node address <1.1.17>, network identity 1000
>Debug: sleeping function called from invalid context at mm/slab.c:1967
>in_atomic():1, irqs_disabled():0
>Call Trace:
> [<c011cce9>] __might_sleep+0x99/0xb0
> [<c014951f>] kmem_cache_alloc+0x21f/0x230
> [<c036c70e>] sock_alloc_inode+0x1e/0x80
> [<c017f9ac>] alloc_inode+0x1c/0x140
> [<c018055d>] new_inode+0x1d/0xd0
> [<c037e742>] rtnl_lock+0x22/0x40
> [<c036ca36>] sock_alloc+0x16/0x60
> [<c036d846>] sock_create+0x86/0x230
> [<f8e5e9ec>] enable_bearer+0xac/0x470 [tipc]
> [<f8e464f7>] tipc_enable_bearer+0x227/0x4b0 [tipc]
> [<f8e5ee88>] udp_media_start+0xc8/0xd0 [tipc]
> [<f8e6b099>] tipc_init+0x99/0xa7 [tipc]
> [<c013a7b9>] sys_init_module+0x179/0x2f0
> [<c0105373>] syscall_call+0x7/0xb
>                                   
>TIPC:  TIPC/UDP: Multicast listener socket on 225.0.1.232:55555
>TIPC:  TIPC/UDP: Unicast listener socket on port 55555
>TIPC:  Bearer instance <udp:udp0> enabled, broadcast domain <1.0.0>
>[root@cl017 root]# Debug: sleeping function called from invalid context at net/core/sock.c:1150
>in_atomic():1, irqs_disabled():0
>Call Trace:
> [<c011cce9>] __might_sleep+0x99/0xb0
> [<c0370632>] lock_sock+0x22/0xc0
> [<c0388d78>] ip_route_output_flow+0x18/0x30
> [<c03b01c4>] udp_sendmsg+0x264/0x800
> [<c0390360>] ip_finish_output2+0x0/0x1e0
> [<c03b950b>] inet_sendmsg+0x4b/0x60
> [<c036cbde>] sock_sendmsg+0x8e/0xb0
> [<c0119584>] recalc_task_prio+0xb4/0x1f0
> [<c01338cb>] kernel_text_address+0x3b/0x50
> [<c01193f8>] kernel_map_pages+0x28/0x64
> [<f8e5a190>] k_signal+0x60/0x170 [tipc]
> [<f8e5a190>] k_signal+0x60/0x170 [tipc]
> [<f8e5e734>] send_msg+0x94/0xa0 [tipc]
> [<f8e398f3>] cfg_send_req+0x1e3/0x230 [tipc]
> [<f8e5a34c>] timeout_receiver+0xac/0x110 [tipc]
> [<f8e5a11f>] receive_signal+0x14f/0x160 [tipc]
> [<c011abc1>] scheduler_tick+0x111/0x690
> [<c0124f33>] tasklet_action+0x73/0xc0
> [<c0124c38>] __do_softirq+0xb8/0xc0
> [<c0124c75>] do_softirq+0x35/0x40
> [<c011526d>] smp_apic_timer_interrupt+0xdd/0x150
> [<c0103040>] default_idle+0x0/0x40
> [<c0105d62>] apic_timer_interrupt+0x1a/0x20
> [<c0103040>] default_idle+0x0/0x40
> [<c0103070>] default_idle+0x30/0x40
> [<c0103106>] cpu_idle+0x46/0x50
> [<c0120561>] printk+0x1c1/0x270
>                                 
>Debug: sleeping function called from invalid context at net/core/sock.c:1150
>in_atomic():1, irqs_disabled():0
>Call Trace:
> [<c011cce9>] __might_sleep+0x99/0xb0
> [<c0370632>] lock_sock+0x22/0xc0
> [<c0388d78>] ip_route_output_flow+0x18/0x30
> [<c03b01c4>] udp_sendmsg+0x264/0x800
> [<c0370c57>] __kfree_skb+0x77/0xf0
> [<c03b950b>] inet_sendmsg+0x4b/0x60
> [<c036cbde>] sock_sendmsg+0x8e/0xb0
> [<c0119584>] recalc_task_prio+0xb4/0x1f0
> [<c0119c1a>] wake_up_state+0x1a/0x20
> [<c012ac22>] signal_wake_up+0x32/0x50
> [<f8e5a190>] k_signal+0x60/0x170 [tipc]
> [<f8e5a190>] k_signal+0x60/0x170 [tipc]
> [<f8e5e734>] send_msg+0x94/0xa0 [tipc]
> [<f8e398f3>] cfg_send_req+0x1e3/0x230 [tipc]
> [<f8e5a34c>] timeout_receiver+0xac/0x110 [tipc]
> [<f8e5a11f>] receive_signal+0x14f/0x160 [tipc]
> [<c011abc1>] scheduler_tick+0x111/0x690
> [<c0124f33>] tasklet_action+0x73/0xc0
> [<c0124c38>] __do_softirq+0xb8/0xc0
> [<c0124c75>] do_softirq+0x35/0x40
> [<c011526d>] smp_apic_timer_interrupt+0xdd/0x150
> [<c0103040>] default_idle+0x0/0x40
> [<c0105d62>] apic_timer_interrupt+0x1a/0x20
> [<c0103040>] default_idle+0x0/0x40
> [<c0103070>] default_idle+0x30/0x40
> [<c0103106>] cpu_idle+0x46/0x50
> [<c0120561>] printk+0x1c1/0x270
>                                 
>rmmod tipc
>TIPC:  Deregistered
>
>  
>