Re: [External] Re: [PATCH 1/2] QSLIST: add atomic replace operation

[王洪浩]

This function is indeed a bit vague in semantics.
I'll modify this function to make it more in line with `replace`.

Stefan Hajnoczi <stefanha@redhat.com> 于2020年8月24日周一 下午11:27写道：
>
> On Mon, Aug 24, 2020 at 12:31:20PM +0800, wanghonghao wrote:
> > Replace a queue with another atomicly. It's useful when we need to transfer
> > queues between threads.
> >
> > Signed-off-by: wanghonghao <wanghonghao@bytedance.com>
> > ---
> >  include/qemu/queue.h | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/include/qemu/queue.h b/include/qemu/queue.h
> > index 456a5b01ee..a3ff544193 100644
> > --- a/include/qemu/queue.h
> > +++ b/include/qemu/queue.h
> > @@ -226,6 +226,10 @@ struct {                                               
> >                  \
> >          (dest)->slh_first = atomic_xchg(&(src)->slh_first, NULL);        \
> >  } while (/*CONSTCOND*/0)
> >
> > +#define QSLIST_REPLACE_ATOMIC(dest, src) do {                              
> >    \
> > +        (src)->slh_first = atomic_xchg(&(dest)->slh_first, 
> > (src)->slh_first); \
> > +} while (/*CONSTCOND*/0)
>
> This is atomic for dest but not src.
>
> Maybe the name should make this clear: QSLIST_REPLACE_ATOMIC_DEST().
>
> Please also add a doc comment mentioning that the modification to src is
> not atomic.
>
> Stefan