diff options
| author | Paolo Bonzini <pbonzini@redhat.com> | 2014-12-02 12:05:47 +0100 |
|---|---|---|
| committer | Stefan Hajnoczi <stefanha@redhat.com> | 2015-01-13 13:43:29 +0000 |
| commit | c740ad92d0d958fa785e5d7aa1b67ecaf30a6a54 (patch) | |
| tree | 9294b5dcdf00456ad6f8823ef7891d76ff45e003 | |
| parent | 6d86ae0824bdd6175dd3874688a871e981093888 (diff) | |
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>
| -rw-r--r-- | include/qemu/queue.h | 15 |
1 files 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 { \ |