drivers: net: xgene: Fix regression in CRC stripping

All packets on ingress (except for jumbo) are terminated with a 4-bytes
CRC checksum. It's the responsability of the driver to strip those 4
bytes. Unfortunately a change dating back to March 2017 re-shuffled some
code and made the CRC stripping code effectively dead.

This change re-orders that part a bit such that the datalen is
immediately altered if needed.

Fixes: 4902a92270fb ("drivers: net: xgene: Add workaround for errata 10GE_8/ENET_11")
Cc: stable@vger.kernel.org
Signed-off-by: Stephane Graber <stgraber@ubuntu.com>
Tested-by: Stephane Graber <stgraber@ubuntu.com>
Link: https://lore.kernel.org/r/20220322224205.752795-1-stgraber@ubuntu.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/apm/xgene/xgene_enet_main.c b/drivers/net/ethernet/apm/xgene/xgene_enet_main.c
index ff2d099..53dc8d5 100644 (file)
--- a/drivers/net/ethernet/apm/xgene/xgene_enet_main.c
+++ b/drivers/net/ethernet/apm/xgene/xgene_enet_main.c
@@ -696,6 +696,12 @@ static int xgene_enet_rx_frame(struct xgene_enet_desc_ring *rx_ring,
        buf_pool->rx_skb[skb_index] = NULL;
 
        datalen = xgene_enet_get_data_len(le64_to_cpu(raw_desc->m1));
+
+       /* strip off CRC as HW isn't doing this */
+       nv = GET_VAL(NV, le64_to_cpu(raw_desc->m0));
+       if (!nv)
+               datalen -= 4;
+
        skb_put(skb, datalen);
        prefetch(skb->data - NET_IP_ALIGN);
        skb->protocol = eth_type_trans(skb, ndev);
@@ -717,12 +723,8 @@ static int xgene_enet_rx_frame(struct xgene_enet_desc_ring *rx_ring,
                }
        }
 
-       nv = GET_VAL(NV, le64_to_cpu(raw_desc->m0));
-       if (!nv) {
-               /* strip off CRC as HW isn't doing this */
-               datalen -= 4;
+       if (!nv)
                goto skip_jumbo;
-       }
 
        slots = page_pool->slots - 1;
        head = page_pool->head;