Re: [PATCH net-next v5 2/3] net: ethernet: rmnet: Support for ingress MAPv5 checksum offload

On 2021-04-23 18:18, Alex Elder wrote:

On 4/23/21 7:19 AM, Sharath Chandra Vurukala wrote:

quoted

Adding support for processing of MAPv5 downlink packets.
It involves parsing the Mapv5 packet and checking the csum header
to know whether the hardware has validated the checksum and is
valid or not.

Based on the checksum valid bit the corresponding stats are
incremented and skb->ip_summed is marked either CHECKSUM_UNNECESSARY
or left as CHEKSUM_NONE to let network stack revalidate the checksum
and update the respective snmp stats.

Current MAPV1 header has been modified, the reserved field in the
Mapv1 header is now used for next header indication.

Acked-by: Subash Abhinov Kasiviswanathan <redacted>
Acked-by: Alex Elder <redacted>

I did not acknowledge this message.  I did for patch 1
only, which only updates the documentation.

I have a few other minor things I recommend you fix.

I don't see any bugs, but I'm not going to offer
"Reviewed-by" until you've had a chance to either
update your patch or explain why you won't.

Sorry Alex for Adding Acked-by on all the patches, will remove in the 
subsequent patch.

quoted

Signed-off-by: Sharath Chandra Vurukala <redacted>
---
  .../net/ethernet/qualcomm/rmnet/rmnet_handlers.c   | 17 ++++---
  drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h    |  3 +-
  .../net/ethernet/qualcomm/rmnet/rmnet_map_data.c   | 58 
+++++++++++++++++++++-
  include/linux/if_rmnet.h                           | 27 +++++++++-
  include/uapi/linux/if_link.h                       |  1 +
  5 files changed, 97 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c 

b/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c
index 0be5ac7..706a225 100644

--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c

@@ -1,5 +1,5 @@
  // SPDX-License-Identifier: GPL-2.0-only
-/* Copyright (c) 2013-2018, The Linux Foundation. All rights 

reserved.
+/* Copyright (c) 2013-2018, 2021, The Linux Foundation. All rights 
reserved.
   *
   * RMNET Data ingress/egress handler
   */

@@ -82,11 +82,16 @@ __rmnet_map_ingress_handler(struct sk_buff *skb,
    	skb->dev = ep->egress_dev;
  -	/* Subtract MAP header */
-	skb_pull(skb, sizeof(struct rmnet_map_header));
-	rmnet_set_skb_proto(skb);
-
-	if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV4) {
+	if ((port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV5) &&
+	    (map_header->flags & MAP_NEXT_HEADER_FLAG)) {
+		if (rmnet_map_process_next_hdr_packet(skb, len))
+			goto free_skb;
+		skb_pull(skb, sizeof(*map_header));
+		rmnet_set_skb_proto(skb);
+	} else if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV4) {
+		/* Subtract MAP header */
+		skb_pull(skb, sizeof(*map_header));
+		rmnet_set_skb_proto(skb);
  		if (!rmnet_map_checksum_downlink_packet(skb, len + pad))
  			skb->ip_summed = CHECKSUM_UNNECESSARY;
  	}

diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h 

b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h
index 2aea153..1a399bf 100644

--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h

@@ -1,5 +1,5 @@
  /* SPDX-License-Identifier: GPL-2.0-only */
-/* Copyright (c) 2013-2018, The Linux Foundation. All rights 

reserved.
+/* Copyright (c) 2013-2018, 2021, The Linux Foundation. All rights 
reserved.
   */
    #ifndef _RMNET_MAP_H_

@@ -48,5 +48,6 @@ void rmnet_map_command(struct sk_buff *skb, struct 

rmnet_port *port);
  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);
+int rmnet_map_process_next_hdr_packet(struct sk_buff *skb, u16 len);
    #endif /* _RMNET_MAP_H_ */

diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c 

b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
index 0ac2ff8..43813cf 100644

--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c

@@ -1,5 +1,5 @@
  // SPDX-License-Identifier: GPL-2.0-only
-/* Copyright (c) 2013-2018, The Linux Foundation. All rights 

reserved.
+/* Copyright (c) 2013-2018, 2021, The Linux Foundation. All rights 
reserved.
   *
   * RMNET Data MAP protocol
   */

@@ -8,6 +8,7 @@
  #include <linux/ip.h>
  #include <linux/ipv6.h>
  #include <net/ip6_checksum.h>
+#include <linux/bitfield.h>
  #include "rmnet_config.h"
  #include "rmnet_map.h"
  #include "rmnet_private.h"

@@ -300,8 +301,11 @@ struct rmnet_map_header 

*rmnet_map_add_map_header(struct sk_buff *skb,
  struct sk_buff *rmnet_map_deaggregate(struct sk_buff *skb,
  				      struct rmnet_port *port)
  {
+	struct rmnet_map_v5_csum_header *next_hdr = NULL;
+	unsigned char *data = skb->data;

If you define the data variable to have (void *) type you can
get rid of some casts below, and it won't need to use a cast
when assigned here either.

I will correct this and the all the comments related to the "data" 
variable in the subsequent patch.

quoted

  	struct rmnet_map_header *maph;
  	struct sk_buff *skbn;
+	u8 nexthdr_type;
  	u32 packet_len;
    	if (skb->len == 0)

@@ -312,6 +316,17 @@ struct sk_buff *rmnet_map_deaggregate(struct 

sk_buff *skb,
    	if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV4)
  		packet_len += sizeof(struct rmnet_map_dl_csum_trailer);

This block should be surrounded by curly braces.  If one block
in an if statement (or chain of them) has them, they all should.

Will correct this in the next patch.

quoted

+	else if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV5) {
+		if (!(maph->flags & MAP_CMD_FLAG)) {
+			packet_len += sizeof(struct rmnet_map_v5_csum_header);

			packet_len += sizeof(*next_hdr);

quoted

+			if (maph->flags & MAP_NEXT_HEADER_FLAG)
+				next_hdr = (struct rmnet_map_v5_csum_header *)
+						(data + sizeof(*maph));

If data is a void pointer, this could be:
				next_hdr = data + sizeof(*maph);

quoted

+			else
+				/* Mapv5 data pkt without csum hdr is invalid */
+				return NULL;
+		}
+	}
    	if (((int)skb->len - (int)packet_len) < 0)
  		return NULL;

@@ -320,6 +335,13 @@ struct sk_buff *rmnet_map_deaggregate(struct 

sk_buff *skb,
  	if (!maph->pkt_len)
  		return NULL;
  +	if (next_hdr) {
+		nexthdr_type = u8_get_bits(next_hdr->header_info,
+					   MAPV5_HDRINFO_HDR_TYPE_FMASK);
+		if (nexthdr_type != RMNET_MAP_HEADER_TYPE_CSUM_OFFLOAD)
+			return NULL;
+	}
+
  	skbn = alloc_skb(packet_len + RMNET_MAP_DEAGGR_SPACING, 
GFP_ATOMIC);
  	if (!skbn)
  		return NULL;

@@ -414,3 +436,37 @@ void rmnet_map_checksum_uplink_packet(struct 

sk_buff *skb,
    	priv->stats.csum_sw++;
  }
+
+/* Process a MAPv5 packet header */
+int rmnet_map_process_next_hdr_packet(struct sk_buff *skb,
+				      u16 len)
+{
+	struct rmnet_priv *priv = netdev_priv(skb->dev);
+	struct rmnet_map_v5_csum_header *next_hdr;
+	u8 nexthdr_type;
+	int rc = 0;
+
+	next_hdr = (struct rmnet_map_v5_csum_header *)(skb->data +
+			sizeof(struct rmnet_map_header));
+
+	nexthdr_type = u8_get_bits(next_hdr->header_info,
+				   MAPV5_HDRINFO_HDR_TYPE_FMASK);
+
+	if (nexthdr_type == RMNET_MAP_HEADER_TYPE_CSUM_OFFLOAD) {
+		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(struct rmnet_map_v5_csum_header));

        skb_pull(skb, sizeof(*next_hdr);

quoted

+	} else {
+		return -EINVAL;
+	}
+
+	return rc;
+}

diff --git a/include/linux/if_rmnet.h b/include/linux/if_rmnet.h
index 4efb537..f82e37e 100644
--- a/include/linux/if_rmnet.h
+++ b/include/linux/if_rmnet.h

@@ -1,5 +1,5 @@
  /* SPDX-License-Identifier: GPL-2.0-only
- * Copyright (c) 2013-2019, The Linux Foundation. All rights 

reserved.
+ * Copyright (c) 2013-2019, 2021 The Linux Foundation. All rights 
reserved.
   */
    #ifndef _LINUX_IF_RMNET_H_

@@ -14,8 +14,10 @@ struct rmnet_map_header {
  /* rmnet_map_header flags field:
   *  PAD_LEN:	number of pad bytes following packet data
   *  CMD:	1 = packet contains a MAP command; 0 = packet contains data
+ *  NEXT_HEADER	1 = packet contains V5 CSUM header 0 = no V5 CSUM 

header
   */
  #define MAP_PAD_LEN_MASK		GENMASK(5, 0)
+#define MAP_NEXT_HEADER_FLAG		BIT(6)
  #define MAP_CMD_FLAG			BIT(7)
    struct rmnet_map_dl_csum_trailer {

@@ -45,4 +47,27 @@ struct rmnet_map_ul_csum_header {
  #define MAP_CSUM_UL_UDP_FLAG		BIT(14)
  #define MAP_CSUM_UL_ENABLED_FLAG	BIT(15)
  +/* MAP CSUM headers */
+struct rmnet_map_v5_csum_header {
+	u8 header_info;
+	u8 csum_info;
+	__be16 reserved;
+} __aligned(1);
+
+/* v5 header_info field
+ * NEXT_HEADER:  Represents whether there is any other header
+ * HEADER TYPE: represents the type of this header
+ *
+ * csum_info field
+ * CSUM_VALID_OR_REQ:
+ * 1 = for UL, checksum computation is requested.
+ * 1 = for DL, validated the checksum and has found it valid
+ */
+
+#define MAPV5_HDRINFO_NXT_HDR_FLAG	BIT(0)
+#define MAPV5_HDRINFO_HDR_TYPE_SHIFT	1
+#define MAPV5_HDRINFO_HDR_TYPE_FMASK	GENMASK(7, 

MAPV5_HDRINFO_HDR_TYPE_SHIFT)
+#define MAPV5_CSUMINFO_VALID_FLAG	BIT(7)

This is the only place you use MAPV5_HDRINFO_TYPE_SHIFT.
Defining and using it here immediately after its definition
subtracts, rather than adds value.  Just do:

#define MAPV5_HDRINFO_HDR_TYPE_FMASK    GENMASK(7, 1)

					-Alex

The MAPV5_HDRINFO_HDR_TYPE_SHIFT is used in the uplink to set the 
header_type in the
header_info field. Will use u8_encode_bits and get rid of this in next 
patch.

quoted

+#define RMNET_MAP_HEADER_TYPE_CSUM_OFFLOAD 2
  #endif /* !(_LINUX_IF_RMNET_H_) */

diff --git a/include/uapi/linux/if_link.h 

b/include/uapi/linux/if_link.h
index 91c8dda..21529b3 100644

--- a/include/uapi/linux/if_link.h
+++ b/include/uapi/linux/if_link.h

@@ -1235,6 +1235,7 @@ enum {
  #define RMNET_FLAGS_INGRESS_MAP_COMMANDS          (1U << 1)
  #define RMNET_FLAGS_INGRESS_MAP_CKSUMV4           (1U << 2)
  #define RMNET_FLAGS_EGRESS_MAP_CKSUMV4            (1U << 3)
+#define RMNET_FLAGS_INGRESS_MAP_CKSUMV5           (1U << 4)
    enum {
  	IFLA_RMNET_UNSPEC,