Re: [Qemu-devel] qemu_futex_wait() lockups in ARM64: 2 possible issues

[Jan Glauber]

On Wed, Oct 09, 2019 at 11:15:04AM +0200, Paolo Bonzini wrote:
> On 09/10/19 10:02, Jan Glauber wrote:

> > I'm still not sure what the actual issue is here, but could it be some bad
> > interaction between the notify_me and the list_lock? The are both 4 byte
> > and side-by-side:
> > 
> > address notify_me: 0xaaaadb528aa0  sizeof notify_me: 4
> > address list_lock: 0xaaaadb528aa4  sizeof list_lock: 4
> > 
> > AFAICS the generated code looks OK (all load/store exclusive done
> > with 32 bit size):
> > 
> >      e6c:       885ffc01        ldaxr   w1, [x0]
> >      e70:       11000821        add     w1, w1, #0x2
> >      e74:       8802fc01        stlxr   w2, w1, [x0]
> > 
> > ...but if I bump notify_me size to uint64_t the issue goes away.
> 
> Ouch. :)  Is this with or without my patch(es)?
> 
> Also, what if you just add a dummy uint32_t after notify_me?

With the dummy the testcase also runs fine for 500 iterations.

Dann, can you try if this works on the Hi1620 too?

--Jan