From c740ad92d0d958fa785e5d7aa1b67ecaf30a6a54 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Tue, 2 Dec 2014 12:05:47 +0100 Subject: [PATCH] QSLIST: add lock-free operations These operations are trivial to implement and do not have ABA problems. They are enough to implement simple multiple-producer, single consumer lock-free lists or, as in the next patch, the multiple consumers can steal a whole batch of elements and process them at their leisure. Signed-off-by: Paolo Bonzini Reviewed-by: Fam Zheng Message-id: 1417518350-6167-5-git-send-email-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi --- include/qemu/queue.h | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/include/qemu/queue.h b/include/qemu/queue.h index 42bcadfbb1..a98eb3ad79 100644 --- a/include/qemu/queue.h +++ b/include/qemu/queue.h @@ -191,8 +191,19 @@ struct { \ } while (/*CONSTCOND*/0) #define QSLIST_INSERT_HEAD(head, elm, field) do { \ - (elm)->field.sle_next = (head)->slh_first; \ - (head)->slh_first = (elm); \ + (elm)->field.sle_next = (head)->slh_first; \ + (head)->slh_first = (elm); \ +} while (/*CONSTCOND*/0) + +#define QSLIST_INSERT_HEAD_ATOMIC(head, elm, field) do { \ + do { \ + (elm)->field.sle_next = (head)->slh_first; \ + } while (atomic_cmpxchg(&(head)->slh_first, (elm)->field.sle_next, \ + (elm)) != (elm)->field.sle_next); \ +} while (/*CONSTCOND*/0) + +#define QSLIST_MOVE_ATOMIC(dest, src) do { \ + (dest)->slh_first = atomic_xchg(&(src)->slh_first, NULL); \ } while (/*CONSTCOND*/0) #define QSLIST_REMOVE_HEAD(head, field) do { \ -- GitLab