[PATCH 4.9 15/63] qed: Fix qed_ll2_post_rx_buffer_notify_fw() by adding a write memory barrier

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 46721c3d9e273aea880e9ff835b0e1271e1cd2fb ]

Make sure chain element is updated before ringing the doorbell.

Signed-off-by: Denis Bolotin <dbolotin@xxxxxxxxxxx>
Signed-off-by: Ariel Elior <aelior@xxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/net/ethernet/qlogic/qed/qed_ll2.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/ethernet/qlogic/qed/qed_ll2.c b/drivers/net/ethernet/qlogic/qed/qed_ll2.c
index a3360cbdb30bd..5b968e6a0a7fb 100644
--- a/drivers/net/ethernet/qlogic/qed/qed_ll2.c
+++ b/drivers/net/ethernet/qlogic/qed/qed_ll2.c
@@ -1013,6 +1013,10 @@ static void qed_ll2_post_rx_buffer_notify_fw(struct qed_hwfn *p_hwfn,
 	cq_prod = qed_chain_get_prod_idx(&p_rx->rcq_chain);
 	rx_prod.bd_prod = cpu_to_le16(bd_prod);
 	rx_prod.cqe_prod = cpu_to_le16(cq_prod);
+
+	/* Make sure chain element is updated before ringing the doorbell */
+	dma_wmb();
+
 	DIRECT_REG_WR(p_rx->set_prod_addr, *((u32 *)&rx_prod));
 }
 
-- 
2.19.1