[dpdk-dev] [PATCH] lib: move rte_ring read barrier to correct location

Juhamatti Kuusisaari juhamatti.kuusisaari at coriant.com
Mon Jul 11 12:20:55 CEST 2016


Fix the location of the rte_ring data dependency read barrier.
It needs to be called before accessing indexed data to ensure
that the data itself is guaranteed to be correctly updated.

See more details at kernel/Documentation/memory-barriers.txt
section 'Data dependency barriers'.

Signed-off-by: Juhamatti Kuusisaari <juhamatti.kuusisaari at coriant.com>
---
 lib/librte_ring/rte_ring.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/librte_ring/rte_ring.h b/lib/librte_ring/rte_ring.h
index eb45e41..a923e49 100644
--- a/lib/librte_ring/rte_ring.h
+++ b/lib/librte_ring/rte_ring.h
@@ -662,9 +662,10 @@ __rte_ring_mc_do_dequeue(struct rte_ring *r, void **obj_table,
                                              cons_next);
        } while (unlikely(success == 0));

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

        /*
         * If there are other dequeues in progress that preceded us,
@@ -746,9 +747,10 @@ __rte_ring_sc_do_dequeue(struct rte_ring *r, void **obj_table,
        cons_next = cons_head + n;
        r->cons.head = cons_next;

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

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


============================================================
The information contained in this message may be privileged
and confidential and protected from disclosure. If the reader
of this message is not the intended recipient, or an employee
or agent responsible for delivering this message to the
intended recipient, you are hereby notified that any reproduction,
dissemination or distribution of this communication is strictly
prohibited. If you have received this communication in error,
please notify us immediately by replying to the message and
deleting it from your computer. Thank you. Coriant-Tellabs
============================================================


More information about the dev mailing list