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Re: [PATCH 1/2] QSLIST: add atomic replace operation
From: |
Stefan Hajnoczi |
Subject: |
Re: [PATCH 1/2] QSLIST: add atomic replace operation |
Date: |
Mon, 24 Aug 2020 16:26:59 +0100 |
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
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