The barrier needs to be after reading the DD bit. It has not been
a problem because the potential reads which can not happen before
reading the DD bit seem to be far enough, so the compiler is not
rescheduling them. However, a refactoring could make this problem
to arise.
Fixes: b812daadad0d ("nfp: add Rx and Tx")
Signed-off-by: Alejandro Lucero <alejandro.luc...@netronome.com>
---
drivers/net/nfp/nfp_net.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/net/nfp/nfp_net.c b/drivers/net/nfp/nfp_net.c
index 5180a31..fc501d6 100644
--- a/drivers/net/nfp/nfp_net.c
+++ b/drivers/net/nfp/nfp_net.c
@@ -2019,16 +2019,16 @@ enum nfp_qcp_ptr {
break;
}
+ rxds = &rxq->rxds[rxq->rd_p];
+ if ((rxds->rxd.meta_len_dd & PCIE_DESC_RX_DD) == 0)
+ break;
+
/*
* Memory barrier to ensure that we won't do other
* reads before the DD bit.
*/
rte_rmb();
- rxds = &rxq->rxds[rxq->rd_p];
- if ((rxds->rxd.meta_len_dd & PCIE_DESC_RX_DD) == 0)
- break;
-
/*
* We got a packet. Let's alloc a new mbuff for refilling the
* free descriptor ring as soon as possible
--
1.9.1
