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[Qemu-devel] [PATCH 4/7] QSLIST: add lock-free operations
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH 4/7] QSLIST: add lock-free operations |
Date: |
Fri, 28 Nov 2014 15:12:18 +0100 |
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 <address@hidden>
---
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
[Qemu-devel] [PATCH 6/7] coroutine: drop qemu_coroutine_adjust_pool_size, Paolo Bonzini, 2014/11/28
[Qemu-devel] [PATCH 7/7] coroutine: try harder not to delete coroutines, Paolo Bonzini, 2014/11/28