[PATCH net-next v2 3/8] net: qualcomm: rmnet: Process MAPv5 frames as a list

[Subash Abhinov Kasiviswanathan <subash.a.kasiviswanathan@oss.qualcomm.com>]

Add support for handling the MAP packets as a list in preparation for
the subsequent patch in the series  which adds support for handling the
coalescing packets. This is needed as a single coalescing MAP packet could
yield multiple IP packets.

There is no functional change in the handling of the previously
supported MAP packet formats.

Co-developed-by: Sean Tranchetti <sean.tranchetti@oss.qualcomm.com>
Signed-off-by: Sean Tranchetti <sean.tranchetti@oss.qualcomm.com>
Signed-off-by: Subash Abhinov Kasiviswanathan <subash.a.kasiviswanathan@oss.qualcomm.com>
---
v2: no change
v1: https://lore.kernel.org/all/20260930051345.857443-3-subash.a.kasiviswanathan@oss.qualcomm.com/

 .../ethernet/qualcomm/rmnet/rmnet_handlers.c  | 22 +++++--
 .../net/ethernet/qualcomm/rmnet/rmnet_map.h   |  4 +-
 .../ethernet/qualcomm/rmnet/rmnet_map_data.c  | 57 ++++++++++++-------
 3 files changed, 58 insertions(+), 25 deletions(-)

diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c
index aa5523f4618e..ab1dfbd833e3 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c
@@ -50,6 +50,16 @@ rmnet_deliver_skb(struct sk_buff *skb)
 	gro_cells_receive(&priv->gro_cells, skb);
 }
 
+static void rmnet_deliver_skb_list(struct sk_buff_head *head)
+{
+	struct sk_buff *skb;
+
+	while ((skb = __skb_dequeue(head))) {
+		rmnet_set_skb_proto(skb);
+		rmnet_deliver_skb(skb);
+	}
+}
+
 /* MAP handler */
 
 static void
@@ -59,6 +69,7 @@ __rmnet_map_ingress_handler(struct sk_buff *skb,
 {
 	struct rmnet_map_header *map_header = (void *)skb->data;
 	struct rmnet_endpoint *ep;
+	struct sk_buff_head list;
 	u16 len, pad;
 	u8 mux_id;
 
@@ -83,12 +94,12 @@ __rmnet_map_ingress_handler(struct sk_buff *skb,
 
 	skb->dev = ep->egress_dev;
 
+	__skb_queue_head_init(&list);
+
 	if ((data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV5) &&
 	    (map_header->flags & MAP_NEXT_HEADER_FLAG)) {
-		if (rmnet_map_process_next_hdr_packet(skb, len))
+		if (rmnet_map_process_next_hdr_packet(skb, &list, len))
 			goto free_skb;
-		skb_pull(skb, sizeof(*map_header));
-		rmnet_set_skb_proto(skb);
 	} else {
 		/* Subtract MAP header */
 		skb_pull(skb, sizeof(*map_header));
@@ -96,10 +107,11 @@ __rmnet_map_ingress_handler(struct sk_buff *skb,
 		if (data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV4 &&
 		    !rmnet_map_checksum_downlink_packet(skb, len + pad))
 			skb->ip_summed = CHECKSUM_UNNECESSARY;
+		skb_trim(skb, len);
+		__skb_queue_tail(&list, skb);
 	}
 
-	skb_trim(skb, len);
-	rmnet_deliver_skb(skb);
+	rmnet_deliver_skb_list(&list);
 	return;
 
 free_skb:
diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h
index 0977e495f591..ef738ce015d4 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h
@@ -53,7 +53,9 @@ void rmnet_map_checksum_uplink_packet(struct sk_buff *skb,
 				      struct rmnet_port *port,
 				      struct net_device *orig_dev,
 				      int csum_type);
-int rmnet_map_process_next_hdr_packet(struct sk_buff *skb, u16 len);
+int rmnet_map_process_next_hdr_packet(struct sk_buff *skb,
+				      struct sk_buff_head *list,
+				      u16 len);
 unsigned int rmnet_map_tx_aggregate(struct sk_buff *skb, struct rmnet_port *port,
 				    struct net_device *orig_dev);
 void rmnet_map_tx_aggregate_init(struct rmnet_port *port);
diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
index 39d6d084e73f..577f2758e385 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
@@ -497,35 +497,54 @@ void rmnet_map_checksum_uplink_packet(struct sk_buff *skb,
 	}
 }
 
-/* Process a MAPv5 packet header */
+static struct rmnet_map_v5_csum_header *
+rmnet_map_get_next_hdr(struct sk_buff *skb)
+{
+	return (struct rmnet_map_v5_csum_header *)(skb->data +
+						   sizeof(struct rmnet_map_header));
+}
+
+static u8 rmnet_map_get_next_hdr_type(struct sk_buff *skb)
+{
+	struct rmnet_map_v5_csum_header *hdr = rmnet_map_get_next_hdr(skb);
+
+	return u8_get_bits(hdr->header_info, MAPV5_HDRINFO_HDR_TYPE_FMASK);
+}
+
+static bool rmnet_map_get_csum_valid(struct sk_buff *skb)
+{
+	struct rmnet_map_v5_csum_header *hdr = rmnet_map_get_next_hdr(skb);
+
+	return !!(hdr->csum_info & MAPV5_CSUMINFO_VALID_FLAG);
+}
+
 int rmnet_map_process_next_hdr_packet(struct sk_buff *skb,
+				      struct sk_buff_head *list,
 				      u16 len)
 {
 	struct rmnet_priv *priv = netdev_priv(skb->dev);
-	struct rmnet_map_v5_csum_header *next_hdr;
-	u8 nexthdr_type;
 
-	next_hdr = (struct rmnet_map_v5_csum_header *)(skb->data +
-			sizeof(struct rmnet_map_header));
+	switch (rmnet_map_get_next_hdr_type(skb)) {
+	case RMNET_MAP_HEADER_TYPE_CSUM_OFFLOAD:
+		if (unlikely(!(skb->dev->features & NETIF_F_RXCSUM))) {
+			priv->stats.csum_sw++;
+		} else if (rmnet_map_get_csum_valid(skb)) {
+			priv->stats.csum_ok++;
+			skb->ip_summed = CHECKSUM_UNNECESSARY;
+		} else {
+			priv->stats.csum_valid_unset++;
+		}
 
-	nexthdr_type = u8_get_bits(next_hdr->header_info,
-				   MAPV5_HDRINFO_HDR_TYPE_FMASK);
+		skb_pull(skb, sizeof(struct rmnet_map_header) +
+			      sizeof(struct rmnet_map_v5_csum_header));
+		skb_trim(skb, len);
+		__skb_queue_tail(list, skb);
+		break;
 
-	if (nexthdr_type != RMNET_MAP_HEADER_TYPE_CSUM_OFFLOAD)
+	default:
 		return -EINVAL;
-
-	if (unlikely(!(skb->dev->features & NETIF_F_RXCSUM))) {
-		priv->stats.csum_sw++;
-	} else if (next_hdr->csum_info & MAPV5_CSUMINFO_VALID_FLAG) {
-		priv->stats.csum_ok++;
-		skb->ip_summed = CHECKSUM_UNNECESSARY;
-	} else {
-		priv->stats.csum_valid_unset++;
 	}
 
-	/* Pull csum v5 header */
-	skb_pull(skb, sizeof(*next_hdr));
-
 	return 0;
 }
 
-- 
2.34.1