net: qualcomm: rmnet: Add support for ethtool private stats

Add ethtool private stats handler to debug the handling of packets
with checksum offload header / trailer. This allows to keep track of
the number of packets for which hardware computes the checksum and
counts and reasons where checksum computation was skipped in hardware
and was done in the network stack.

Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/qualcomm/rmnet/rmnet_config.h

@@ -54,11 +54,24 @@ struct rmnet_pcpu_stats {
 	struct u64_stats_sync syncp;
 };
 
+struct rmnet_priv_stats {
+	u64 csum_ok;
+	u64 csum_valid_unset;
+	u64 csum_validation_failed;
+	u64 csum_err_bad_buffer;
+	u64 csum_err_invalid_ip_version;
+	u64 csum_err_invalid_transport;
+	u64 csum_fragmented_pkt;
+	u64 csum_skipped;
+	u64 csum_sw;
+};
+
 struct rmnet_priv {
 	u8 mux_id;
 	struct net_device *real_dev;
 	struct rmnet_pcpu_stats __percpu *pcpu_stats;
 	struct gro_cells gro_cells;
+	struct rmnet_priv_stats stats;
 };
 
 struct rmnet_port *rmnet_get_port(struct net_device *real_dev);

drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c

@@ -48,7 +48,8 @@ static __sum16 *rmnet_map_get_csum_field(unsigned char protocol,
 
 static int
 rmnet_map_ipv4_dl_csum_trailer(struct sk_buff *skb,
-			       struct rmnet_map_dl_csum_trailer *csum_trailer)
+			       struct rmnet_map_dl_csum_trailer *csum_trailer,
+			       struct rmnet_priv *priv)
 {
 	__sum16 *csum_field, csum_temp, pseudo_csum, hdr_csum, ip_payload_csum;
 	u16 csum_value, csum_value_final;
@@ -58,19 +59,25 @@ rmnet_map_ipv4_dl_csum_trailer(struct sk_buff *skb,
 
 	ip4h = (struct iphdr *)(skb->data);
 	if ((ntohs(ip4h->frag_off) & IP_MF) ||
-	    ((ntohs(ip4h->frag_off) & IP_OFFSET) > 0))
+	    ((ntohs(ip4h->frag_off) & IP_OFFSET) > 0)) {
+		priv->stats.csum_fragmented_pkt++;
 		return -EOPNOTSUPP;
+	}
 
 	txporthdr = skb->data + ip4h->ihl * 4;
 
 	csum_field = rmnet_map_get_csum_field(ip4h->protocol, txporthdr);
 
-	if (!csum_field)
+	if (!csum_field) {
+		priv->stats.csum_err_invalid_transport++;
 		return -EPROTONOSUPPORT;
+	}
 
 	/* RFC 768 - Skip IPv4 UDP packets where sender checksum field is 0 */
-	if (*csum_field == 0 && ip4h->protocol == IPPROTO_UDP)
+	if (*csum_field == 0 && ip4h->protocol == IPPROTO_UDP) {
+		priv->stats.csum_skipped++;
 		return 0;
+	}
 
 	csum_value = ~ntohs(csum_trailer->csum_value);
 	hdr_csum = ~ip_fast_csum(ip4h, (int)ip4h->ihl);
@@ -102,16 +109,20 @@ rmnet_map_ipv4_dl_csum_trailer(struct sk_buff *skb,
 		}
 	}
 
-	if (csum_value_final == ntohs((__force __be16)*csum_field))
+	if (csum_value_final == ntohs((__force __be16)*csum_field)) {
+		priv->stats.csum_ok++;
 		return 0;
-	else
+	} else {
+		priv->stats.csum_validation_failed++;
 		return -EINVAL;
 	}
+}
 
 #if IS_ENABLED(CONFIG_IPV6)
 static int
 rmnet_map_ipv6_dl_csum_trailer(struct sk_buff *skb,
-			       struct rmnet_map_dl_csum_trailer *csum_trailer)
+			       struct rmnet_map_dl_csum_trailer *csum_trailer,
+			       struct rmnet_priv *priv)
 {
 	__sum16 *csum_field, ip6_payload_csum, pseudo_csum, csum_temp;
 	u16 csum_value, csum_value_final;
@@ -125,8 +136,10 @@ rmnet_map_ipv6_dl_csum_trailer(struct sk_buff *skb,
 	txporthdr = skb->data + sizeof(struct ipv6hdr);
 	csum_field = rmnet_map_get_csum_field(ip6h->nexthdr, txporthdr);
 
-	if (!csum_field)
+	if (!csum_field) {
+		priv->stats.csum_err_invalid_transport++;
 		return -EPROTONOSUPPORT;
+	}
 
 	csum_value = ~ntohs(csum_trailer->csum_value);
 	ip6_hdr_csum = (__force __be16)
@@ -164,11 +177,14 @@ rmnet_map_ipv6_dl_csum_trailer(struct sk_buff *skb,
 		}
 	}
 
-	if (csum_value_final == ntohs((__force __be16)*csum_field))
+	if (csum_value_final == ntohs((__force __be16)*csum_field)) {
+		priv->stats.csum_ok++;
 		return 0;
-	else
+	} else {
+		priv->stats.csum_validation_failed++;
 		return -EINVAL;
 	}
+}
 #endif
 
 static void rmnet_map_complement_ipv4_txporthdr_csum_field(void *iphdr)
@@ -339,24 +355,34 @@ struct sk_buff *rmnet_map_deaggregate(struct sk_buff *skb,
  */
 int rmnet_map_checksum_downlink_packet(struct sk_buff *skb, u16 len)
 {
+	struct rmnet_priv *priv = netdev_priv(skb->dev);
 	struct rmnet_map_dl_csum_trailer *csum_trailer;
 
-	if (unlikely(!(skb->dev->features & NETIF_F_RXCSUM)))
+	if (unlikely(!(skb->dev->features & NETIF_F_RXCSUM))) {
+		priv->stats.csum_sw++;
 		return -EOPNOTSUPP;
+	}
 
 	csum_trailer = (struct rmnet_map_dl_csum_trailer *)(skb->data + len);
 
-	if (!csum_trailer->valid)
+	if (!csum_trailer->valid) {
+		priv->stats.csum_valid_unset++;
 		return -EINVAL;
+	}
 
-	if (skb->protocol == htons(ETH_P_IP))
+	if (skb->protocol == htons(ETH_P_IP)) {
-		return rmnet_map_ipv4_dl_csum_trailer(skb, csum_trailer);
+		return rmnet_map_ipv4_dl_csum_trailer(skb, csum_trailer, priv);
-	else if (skb->protocol == htons(ETH_P_IPV6))
+	} else if (skb->protocol == htons(ETH_P_IPV6)) {
 #if IS_ENABLED(CONFIG_IPV6)
-		return rmnet_map_ipv6_dl_csum_trailer(skb, csum_trailer);
+		return rmnet_map_ipv6_dl_csum_trailer(skb, csum_trailer, priv);
 #else
+		priv->stats.csum_err_invalid_ip_version++;
 		return -EPROTONOSUPPORT;
 #endif
+	} else {
+		priv->stats.csum_err_invalid_ip_version++;
+		return -EPROTONOSUPPORT;
+	}
 
 	return 0;
 }
@@ -367,6 +393,7 @@ int rmnet_map_checksum_downlink_packet(struct sk_buff *skb, u16 len)
 void rmnet_map_checksum_uplink_packet(struct sk_buff *skb,
 				      struct net_device *orig_dev)
 {
+	struct rmnet_priv *priv = netdev_priv(orig_dev);
 	struct rmnet_map_ul_csum_header *ul_header;
 	void *iphdr;
 
@@ -389,8 +416,11 @@ void rmnet_map_checksum_uplink_packet(struct sk_buff *skb,
 			rmnet_map_ipv6_ul_csum_header(iphdr, ul_header, skb);
 			return;
 #else
+			priv->stats.csum_err_invalid_ip_version++;
 			goto sw_csum;
 #endif
+		} else {
+			priv->stats.csum_err_invalid_ip_version++;
 		}
 	}
 
@@ -399,4 +429,6 @@ sw_csum:
 	ul_header->csum_insert_offset = 0;
 	ul_header->csum_enabled = 0;
 	ul_header->udp_ip4_ind = 0;
+
+	priv->stats.csum_sw++;
 }

drivers/net/ethernet/qualcomm/rmnet/rmnet_vnd.c

@@ -152,6 +152,56 @@ static const struct net_device_ops rmnet_vnd_ops = {
 	.ndo_get_stats64 = rmnet_get_stats64,
 };
 
+static const char rmnet_gstrings_stats[][ETH_GSTRING_LEN] = {
+	"Checksum ok",
+	"Checksum valid bit not set",
+	"Checksum validation failed",
+	"Checksum error bad buffer",
+	"Checksum error bad ip version",
+	"Checksum error bad transport",
+	"Checksum skipped on ip fragment",
+	"Checksum skipped",
+	"Checksum computed in software",
+};
+
+static void rmnet_get_strings(struct net_device *dev, u32 stringset, u8 *buf)
+{
+	switch (stringset) {
+	case ETH_SS_STATS:
+		memcpy(buf, &rmnet_gstrings_stats,
+		       sizeof(rmnet_gstrings_stats));
+		break;
+	}
+}
+
+static int rmnet_get_sset_count(struct net_device *dev, int sset)
+{
+	switch (sset) {
+	case ETH_SS_STATS:
+		return ARRAY_SIZE(rmnet_gstrings_stats);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static void rmnet_get_ethtool_stats(struct net_device *dev,
+				    struct ethtool_stats *stats, u64 *data)
+{
+	struct rmnet_priv *priv = netdev_priv(dev);
+	struct rmnet_priv_stats *st = &priv->stats;
+
+	if (!data)
+		return;
+
+	memcpy(data, st, ARRAY_SIZE(rmnet_gstrings_stats) * sizeof(u64));
+}
+
+static const struct ethtool_ops rmnet_ethtool_ops = {
+	.get_ethtool_stats = rmnet_get_ethtool_stats,
+	.get_strings = rmnet_get_strings,
+	.get_sset_count = rmnet_get_sset_count,
+};
+
 /* Called by kernel whenever a new rmnet<n> device is created. Sets MTU,
  * flags, ARP type, needed headroom, etc...
  */
@@ -170,6 +220,7 @@ void rmnet_vnd_setup(struct net_device *rmnet_dev)
 	rmnet_dev->flags &= ~(IFF_BROADCAST | IFF_MULTICAST);
 
 	rmnet_dev->needs_free_netdev = true;
+	rmnet_dev->ethtool_ops = &rmnet_ethtool_ops;
 }
 
 /* Exposed API */