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

[wanghonghao]

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)
+
 #define QSLIST_REMOVE_HEAD(head, field) do {                             \
         typeof((head)->slh_first) elm = (head)->slh_first;               \
         (head)->slh_first = elm->field.sle_next;                         \
-- 
2.24.3 (Apple Git-128)