[PATCH 4.19 021/118] qed: Fix reading wrong value in loop condition

[Greg Kroah-Hartman]

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

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

[ Upstream commit ed4eac20dcffdad47709422e0cb925981b056668 ]

The value of "sb_index" is written by the hardware. Reading its value and
writing it to "index" must finish before checking the loop condition.

Signed-off-by: Denis Bolotin <denis.bolotin@xxxxxxxxxx>
Signed-off-by: Michal Kalderon <michal.kalderon@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/net/ethernet/qlogic/qed/qed_int.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/qlogic/qed/qed_int.c b/drivers/net/ethernet/qlogic/qed/qed_int.c
index 0f0aba793352..b22f464ea3fa 100644
--- a/drivers/net/ethernet/qlogic/qed/qed_int.c
+++ b/drivers/net/ethernet/qlogic/qed/qed_int.c
@@ -992,6 +992,8 @@ static int qed_int_attentions(struct qed_hwfn *p_hwfn)
 	 */
 	do {
 		index = p_sb_attn->sb_index;
+		/* finish reading index before the loop condition */
+		dma_rmb();
 		attn_bits = le32_to_cpu(p_sb_attn->atten_bits);
 		attn_acks = le32_to_cpu(p_sb_attn->atten_ack);
 	} while (index != p_sb_attn->sb_index);
-- 
2.19.1