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 <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>
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@ -191,8 +191,19 @@ struct { \
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} while (/*CONSTCOND*/0)
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#define QSLIST_INSERT_HEAD(head, elm, field) do { \
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(elm)->field.sle_next = (head)->slh_first; \
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(head)->slh_first = (elm); \
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(elm)->field.sle_next = (head)->slh_first; \
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(head)->slh_first = (elm); \
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} while (/*CONSTCOND*/0)
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#define QSLIST_INSERT_HEAD_ATOMIC(head, elm, field) do { \
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do { \
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(elm)->field.sle_next = (head)->slh_first; \
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} while (atomic_cmpxchg(&(head)->slh_first, (elm)->field.sle_next, \
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(elm)) != (elm)->field.sle_next); \
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} while (/*CONSTCOND*/0)
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#define QSLIST_MOVE_ATOMIC(dest, src) do { \
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(dest)->slh_first = atomic_xchg(&(src)->slh_first, NULL); \
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} while (/*CONSTCOND*/0)
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#define QSLIST_REMOVE_HEAD(head, field) do { \
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