[ofa-general] Re: dst_ifdown breaks infiniband?

[Michael S. Tsirkin]

> Quoting Alexey Kuznetsov <kuznet at ms2.inr.ac.ru>:
> Subject: Re: dst_ifdown breaks infiniband?
> 
> Hello!
> 
> > Hmm. Something I don't understand: does the code
> > in question not run on *each* device unregister?
> 
> It does.
> 
> 
> > Why do I only see this under stress?
> 
> You should have some referenced destination entries to trigger bad path.
> This should happen not only under stress.
> 
> F.e. just try to ssh to something via this device. And unregister it.
> Seems, the crash is inevitable. If you do not see crash, I will be puzzled.


I did this.
What happens is:

	neigh_setup is called
	dst_ifdown changes the neigh->dev to loopback device

But the funny thing is that this neighbour can thinkably hang
around indefinitely now, and if it does destructor won't be called
and there won't be a crash.

To trigger a crash, I did simply
	ifconfig lo down; ifconfig lo 127.0.0.1

and sure enough it crashes in drivers/infiniband/ulp/ipoib/ipoib_main.c.

-- 
MST