qed: Fix qed_ll2_post_rx_buffer_notify_fw() by adding a write memory barrier

[ Upstream commit 46721c3d ]

Make sure chain element is updated before ringing the doorbell.
Signed-off-by: Denis Bolotin <dbolotin@marvell.com>
Signed-off-by: Ariel Elior <aelior@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/net/ethernet/qlogic/qed/qed_ll2.c

@@ -1487,6 +1487,10 @@ 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));
 }