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QSLIST: add lock-free operations

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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 <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 1417518350-6167-5-git-send-email-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Paolo Bonzini 2014-12-02 12:05:47 +01:00 committed by Stefan Hajnoczi
parent 6d86ae0824
commit c740ad92d0
1 changed files with 13 additions and 2 deletions
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15
include/qemu/queue.h
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@ -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 { \