xenbus api

xenbus api

[Fabien Hermenier]

Hello
I have a lot of problem using the xenbus api (in xen-3.0-testing).

I had to modify the network backend driver (file netback.c), and each
call to a xenbus function in a virtual machine make my machine reboot
(not the virtual, the real machine).

for example, I 've add this line of code (wich is useless):
	printk("%d",xenbus_exists(XBT_NULL,"/local/domain/0/","domid"));
after a network packet reception.

When I launch my virtual machine, the station reboot after the virtual
machine console log is stopped after this block:

TCP: Hash tables configured (established 8192 bind 8192)
NET: Registered protocol family 1
NET: Registered protocol family 17

What do I wrong ? Could I use the xenbus API in the backend (I have same
problem in the frontend) ? Any tips/advice would be appreciate

Regards.
Fabien

Re: xenbus api

[Anthony Liguori]

You have to provide more context than that.  If you're domain boots at 
all, XenBus is working.

It's likely that you're using the XenBus API (which may block) while 
holding a lock in the network driver and causing a nasty dead lock of 
some sort.

Regards,

Anthony Liguori

Fabien Hermenier wrote:
> Hello
> I have a lot of problem using the xenbus api (in xen-3.0-testing).
>
> I had to modify the network backend driver (file netback.c), and each
> call to a xenbus function in a virtual machine make my machine reboot
> (not the virtual, the real machine).
>
> for example, I 've add this line of code (wich is useless):
> 	printk("%d",xenbus_exists(XBT_NULL,"/local/domain/0/","domid"));
> after a network packet reception.
>
> When I launch my virtual machine, the station reboot after the virtual
> machine console log is stopped after this block:
>
> TCP: Hash tables configured (established 8192 bind 8192)
> NET: Registered protocol family 1
> NET: Registered protocol family 17
>
> What do I wrong ? Could I use the xenbus API in the backend (I have same
> problem in the frontend) ? Any tips/advice would be appreciate
>
> Regards.
> Fabien
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel
>   

Re: xenbus api

[Fabien Hermenier]

Hello
I think your right. I've got the same problem if I write the same code
in the netfront.

But this time I can show you the call trace

The call trace:
scheduling while atomic: swapper/0x00000100/1
 [<c0105b23>] show_trace+0x13/0x20
 [<c0105b4e>] dump_stack+0x1e/0x20
 [<c02c54f6>] schedule+0x766/0x860
 [<c0253005>] read_reply+0xe5/0x120
 [<c02530eb>] xs_talkv+0xab/0x1a0
 [<c02534b0>] xs_single+0x40/0x50
 [<c0253593>] xenbus_read+0x33/0x50
 [<c0257277>] xenbus_update_statistics+0x37/0x70 <--- my function
 [<c02597c4>] network_start_xmit+0x214/0x3f0
 [<c0274caf>] qdisc_restart+0x6f/0x280
 [<c0269d6f>] dev_queue_xmit+0x14f/0x3a0
 [<c0257330>] send_fake_arp+0x80/0x90
 [<c0257366>] inetdev_notify+0x26/0x30
 [<c012b7fd>] notifier_call_chain+0x2d/0x50
 [<c02a3d03>] inet_insert_ifa+0xe3/0x170
 [<c02a45bf>] devinet_ioctl+0x37f/0x6a9
 [<c0362e09>] ic_dev_ioctl+0x29/0x40
 [<c0363258>] ip_auto_config+0x3a8/0x84f
 [<c0102186>] init+0x116/0x3e0
 [<c0102c55>] kernel_thread_helper+0x5/0x10

Thanks for helping
Fabien.

Le jeudi 15 juin 2006 à 16:01 -0500, Anthony Liguori a écrit :
> You have to provide more context than that.  If you're domain boots at 
> all, XenBus is working.
> 
> It's likely that you're using the XenBus API (which may block) while 
> holding a lock in the network driver and causing a nasty dead lock of 
> some sort.
> 
> Regards,
> 
> Anthony Liguori
> 
> Fabien Hermenier wrote:
> > Hello
> > I have a lot of problem using the xenbus api (in xen-3.0-testing).
> >
> > I had to modify the network backend driver (file netback.c), and each
> > call to a xenbus function in a virtual machine make my machine reboot
> > (not the virtual, the real machine).
> >
> > for example, I 've add this line of code (wich is useless):
> > 	printk("%d",xenbus_exists(XBT_NULL,"/local/domain/0/","domid"));
> > after a network packet reception.
> >
> > When I launch my virtual machine, the station reboot after the virtual
> > machine console log is stopped after this block:
> >
> > TCP: Hash tables configured (established 8192 bind 8192)
> > NET: Registered protocol family 1
> > NET: Registered protocol family 17
> >
> > What do I wrong ? Could I use the xenbus API in the backend (I have same
> > problem in the frontend) ? Any tips/advice would be appreciate
> >
> > Regards.
> > Fabien
> >
> >
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@lists.xensource.com
> > http://lists.xensource.com/xen-devel
> >   
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel