qed: Fix reading wrong value in loop condition

BugLink: https://bugs.launchpad.net/bugs/1837161
[ 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@cavium.com>
Signed-off-by: Michal Kalderon <michal.kalderon@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/net/ethernet/qlogic/qed/qed_int.c b/drivers/net/ethernet/qlogic/qed/qed_int.c
index 719cdbfe16952f11b2dd23a987abd6df8b805c7e..7746417130bd734e38f5fab00494db6e709e5097 100644 (file)
--- 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);