[dpdk-dev] [PATCH] lib: change rte_ring dequeue to guarantee ordering before tail update

[Juhamatti Kuusisaari]

Consumer queue dequeuing must be guaranteed to be done fully before
the tail is updated. This is not guaranteed with a read barrier,
changed to a write barrier just before tail update which in practice
guarantees correct order of reads and writes.

Signed-off-by: Juhamatti Kuusisaari <juhamatti.kuusisaari at coriant.com>
---
 lib/librte_ring/rte_ring.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/librte_ring/rte_ring.h b/lib/librte_ring/rte_ring.h
index eb45e41..14920af 100644
--- a/lib/librte_ring/rte_ring.h
+++ b/lib/librte_ring/rte_ring.h
@@ -748,7 +748,7 @@ __rte_ring_sc_do_dequeue(struct rte_ring *r, void **obj_table,

        /* copy in table */
        DEQUEUE_PTRS();
-       rte_smp_rmb();
+       rte_smp_wmb();

        __RING_STAT_ADD(r, deq_success, n);
        r->cons.tail = cons_next;
--
2.9.0


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