be2net: Fix to trim skb for padded vlan packets to workaround an ASIC Bug

Fixed spelling error in a comment as pointed out by DaveM.
Also refactored existing code a bit to provide placeholders for another ASIC
Bug workaround that will be checked-in soon after this.

Signed-off-by: Somnath Kotur <somnath.kotur@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 47 insertions, 14 deletions

diff --git a/drivers/net/ethernet/emulex/benet/be.h b/drivers/net/ethernet/emulex/benet/be.h
index 7b5cc2b212e5..7a71fb66c6dc 100644
--- a/drivers/net/ethernet/emulex/benet/be.h
+++ b/drivers/net/ethernet/emulex/benet/be.h
@@ -573,6 +573,11 @@ static inline u8 is_udp_pkt(struct sk_buff *skb)
         return val;
 }
 
+static inline bool is_ipv4_pkt(struct sk_buff *skb)
+{
+        return skb->protocol == ntohs(ETH_P_IP) && ip_hdr(skb)->version == 4;
+}
+
 static inline void be_vf_eth_addr_generate(struct be_adapter *adapter, u8 *mac)
 {
         u32 addr;
diff --git a/drivers/net/ethernet/emulex/benet/be_main.c b/drivers/net/ethernet/emulex/benet/be_main.c
index a28896d4411d..edce7af97c87 100644
--- a/drivers/net/ethernet/emulex/benet/be_main.c
+++ b/drivers/net/ethernet/emulex/benet/be_main.c
@@ -577,6 +577,11 @@ static inline u16 be_get_tx_vlan_tag(struct be_adapter *adapter,
         return vlan_tag;
 }
 
+static int be_vlan_tag_chk(struct be_adapter *adapter, struct sk_buff *skb)
+{
+        return vlan_tx_tag_present(skb) || adapter->pvid;
+}
+
 static void wrb_fill_hdr(struct be_adapter *adapter, struct be_eth_hdr_wrb *hdr,
                 struct sk_buff *skb, u32 wrb_cnt, u32 len)
 {
@@ -704,33 +709,56 @@ dma_err:
         return 0;
 }
 
+static struct sk_buff *be_insert_vlan_in_pkt(struct be_adapter *adapter,
+                                             struct sk_buff *skb)
+{
+        u16 vlan_tag = 0;
+
+        skb = skb_share_check(skb, GFP_ATOMIC);
+        if (unlikely(!skb))
+                return skb;
+
+        if (vlan_tx_tag_present(skb)) {
+                vlan_tag = be_get_tx_vlan_tag(adapter, skb);
+                __vlan_put_tag(skb, vlan_tag);
+                skb->vlan_tci = 0;
+        }
+
+        return skb;
+}
+
 static netdev_tx_t be_xmit(struct sk_buff *skb,
                         struct net_device *netdev)
 {
         struct be_adapter *adapter = netdev_priv(netdev);
         struct be_tx_obj *txo = &adapter->tx_obj[skb_get_queue_mapping(skb)];
         struct be_queue_info *txq = &txo->q;
+        struct iphdr *ip = NULL;
         u32 wrb_cnt = 0, copied = 0;
-        u32 start = txq->head;
+        u32 start = txq->head, eth_hdr_len;
         bool dummy_wrb, stopped = false;
 
-        /* For vlan tagged pkts, BE
-         * 1) calculates checksum even when CSO is not requested
-         * 2) calculates checksum wrongly for padded pkt less than
-         * 60 bytes long.
-         * As a workaround disable TX vlan offloading in such cases.
+        eth_hdr_len = ntohs(skb->protocol) == ETH_P_8021Q ?
+                VLAN_ETH_HLEN : ETH_HLEN;
+
+        /* HW has a bug which considers padding bytes as legal
+         * and modifies the IPv4 hdr's 'tot_len' field
          */
-        if (vlan_tx_tag_present(skb) &&
-            (skb->ip_summed != CHECKSUM_PARTIAL || skb->len <= 60)) {
-                skb = skb_share_check(skb, GFP_ATOMIC);
-                if (unlikely(!skb))
-                        goto tx_drop;
+        if (skb->len <= 60 && be_vlan_tag_chk(adapter, skb) &&
+                        is_ipv4_pkt(skb)) {
+                ip = (struct iphdr *)ip_hdr(skb);
+                pskb_trim(skb, eth_hdr_len + ntohs(ip->tot_len));
+        }
 
-                skb = __vlan_put_tag(skb, be_get_tx_vlan_tag(adapter, skb));
+        /* HW has a bug wherein it will calculate CSUM for VLAN
+         * pkts even though it is disabled.
+         * Manually insert VLAN in pkt.
+         */
+        if (skb->ip_summed != CHECKSUM_PARTIAL &&
+                        be_vlan_tag_chk(adapter, skb)) {
+                skb = be_insert_vlan_in_pkt(adapter, skb);
                 if (unlikely(!skb))
                         goto tx_drop;
-
-                skb->vlan_tci = 0;
         }
 
         wrb_cnt = wrb_cnt_for_skb(adapter, skb, &dummy_wrb);