From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37876) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XvlHh-0005hv-IT for qemu-devel@nongnu.org; Tue, 02 Dec 2014 06:06:27 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XvlHZ-0003kg-5s for qemu-devel@nongnu.org; Tue, 02 Dec 2014 06:06:21 -0500 Received: from mx1.redhat.com ([209.132.183.28]:58465) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XvlHY-0003kc-U7 for qemu-devel@nongnu.org; Tue, 02 Dec 2014 06:06:13 -0500 From: Paolo Bonzini Date: Tue, 2 Dec 2014 12:05:47 +0100 Message-Id: <1417518350-6167-5-git-send-email-pbonzini@redhat.com> In-Reply-To: <1417518350-6167-1-git-send-email-pbonzini@redhat.com> References: <1417518350-6167-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PATCH v2 4/7] QSLIST: add lock-free operations List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: kwolf@redhat.com, ming.lei@canonical.com, pl@kamp.de, stefanha@redhat.com 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 --- 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 d433b90..6a01e2f 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 { \ -- 2.1.0