Re: [Qemu-devel] [PATCH v3 2/2] QEMUBH: make AioContext's bh re-entrant

[Paolo Bonzini]

Il 20/06/2013 11:12, liu ping fan ha scritto:
>> Right.  You need to order ->idle writes before ->scheduled writes, and
>> add memory barriers, or alternatively use two bits in ->scheduled so
>> that you can assign both atomically.
>>
> I think just shift the position of smp_rmb/wmb in _schedule and _poll,
> we can acheive this (callbacks will not refer to ->idle)

Yes, but you also need to swap ->idle and ->scheduled assignments
(aio_bh_poll reads scheduled before idle; qemu_bh_schedule* must write
idle before scheduled).

Paolo