| Message ID | 20200824043121.13421-1-wanghonghao@bytedance.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/2] QSLIST: add atomic replace operation | expand |
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
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
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) + #define QSLIST_REMOVE_HEAD(head, field) do { \ typeof((head)->slh_first) elm = (head)->slh_first; \ (head)->slh_first = elm->field.sle_next; \
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(+)