gve: add gve_features_check()

It is suboptimal to attempt skb linearization from ndo_start_xmit()
if a gso skb has pathological layout, or if host stack does not have
access to the payload (TCP direct). Linearization of large skbs
can also fail under memory pressure.

We should instead have an ndo_features_check() so that we can
fallback to GSO, which is supported even for TCP direct,
and generally much more efficient (no payload copy).

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Bailey Forrest <bcf@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Jeroen de Borst <jeroendb@google.com>
Cc: Praveen Kaligineedi <pkaligineedi@google.com>
Cc: Shailend Chand <shailend@google.com>
Cc: Ziwei Xiao <ziweixiao@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 15 insertions, 22 deletions

diff --git a/drivers/net/ethernet/google/gve/gve_tx_dqo.c b/drivers/net/ethernet/google/gve/gve_tx_dqo.c
index 1e19b834a613..f59c4710f118 100644
--- a/drivers/net/ethernet/google/gve/gve_tx_dqo.c
+++ b/drivers/net/ethernet/google/gve/gve_tx_dqo.c
@@ -843,6 +843,16 @@ static bool gve_can_send_tso(const struct sk_buff *skb)
 	return true;
 }
 
+netdev_features_t gve_features_check_dqo(struct sk_buff *skb,
+					 struct net_device *dev,
+					 netdev_features_t features)
+{
+	if (skb_is_gso(skb) && !gve_can_send_tso(skb))
+		return features & ~NETIF_F_GSO_MASK;
+
+	return features;
+}
+
 /* Attempt to transmit specified SKB.
  *
  * Returns 0 if the SKB was transmitted or dropped.
@@ -854,11 +864,10 @@ static int gve_try_tx_skb(struct gve_priv *priv, struct gve_tx_ring *tx,
 	int num_buffer_descs;
 	int total_num_descs;
 
-	if (tx->dqo.qpl) {
-		if (skb_is_gso(skb))
-			if (unlikely(ipv6_hopopt_jumbo_remove(skb)))
-				goto drop;
+	if (skb_is_gso(skb) && unlikely(ipv6_hopopt_jumbo_remove(skb)))
+		goto drop;
 
+	if (tx->dqo.qpl) {
 		/* We do not need to verify the number of buffers used per
 		 * packet or per segment in case of TSO as with 2K size buffers
 		 * none of the TX packet rules would be violated.
@@ -868,24 +877,8 @@ static int gve_try_tx_skb(struct gve_priv *priv, struct gve_tx_ring *tx,
 		 */
 		num_buffer_descs = DIV_ROUND_UP(skb->len, GVE_TX_BUF_SIZE_DQO);
 	} else {
-		if (skb_is_gso(skb)) {
-			/* If TSO doesn't meet HW requirements, attempt to linearize the
-			 * packet.
-			 */
-			if (unlikely(!gve_can_send_tso(skb) &&
-				     skb_linearize(skb) < 0)) {
-				net_err_ratelimited("%s: Failed to transmit TSO packet\n",
-						    priv->dev->name);
-				goto drop;
-			}
-
-			if (unlikely(ipv6_hopopt_jumbo_remove(skb)))
-				goto drop;
-
-			num_buffer_descs = gve_num_buffer_descs_needed(skb);
-		} else {
-			num_buffer_descs = gve_num_buffer_descs_needed(skb);
-
+		num_buffer_descs = gve_num_buffer_descs_needed(skb);
+		if (!skb_is_gso(skb)) {
 			if (unlikely(num_buffer_descs > GVE_TX_MAX_DATA_DESCS)) {
 				if (unlikely(skb_linearize(skb) < 0))
 					goto drop;