Re: [PATCH net-next 07/10] net: qualcomm: rmnet: Add support for RX checksum offload

[kbuild test robot <lkp@intel.com>]

Hi Subash,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on net-next/master]

url:    https://github.com/0day-ci/linux/commits/Subash-Abhinov-Kasiviswanathan/net-qualcomm-rmnet-Enable-csum-offloads/20171228-041216
reproduce:
        # apt-get install sparse
        make ARCH=x86_64 allmodconfig
        make C=1 CF=-D__CHECK_ENDIAN__


sparse warnings: (new ones prefixed by >>)


vim +30 drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c

    26	
    27	static u16 *rmnet_map_get_csum_field(unsigned char protocol,
    28					     const void *txporthdr)
    29	{
  > 30		u16 *check = 0;
    31	
    32		switch (protocol) {
    33		case IPPROTO_TCP:
  > 34			check = &(((struct tcphdr *)txporthdr)->check);
    35			break;
    36	
    37		case IPPROTO_UDP:
  > 38			check = &(((struct udphdr *)txporthdr)->check);
    39			break;
    40	
    41		default:
    42			check = 0;
    43			break;
    44		}
    45	
    46		return check;
    47	}
    48	
    49	static int
    50	rmnet_map_ipv4_dl_csum_trailer(struct sk_buff *skb,
    51				       struct rmnet_map_dl_csum_trailer *csum_trailer)
    52	{
    53		u16 ip_pseudo_payload_csum, pseudo_csum, ip_hdr_csum, *csum_field;
    54		u16 csum_value, ip_payload_csum, csum_value_final;
    55		struct iphdr *ip4h;
    56		void *txporthdr;
    57	
    58		ip4h = (struct iphdr *)(skb->data);
    59		if ((ntohs(ip4h->frag_off) & IP_MF) ||
    60		    ((ntohs(ip4h->frag_off) & IP_OFFSET) > 0))
    61			return -EOPNOTSUPP;
    62	
    63		txporthdr = skb->data + ip4h->ihl * 4;
    64	
    65		csum_field = rmnet_map_get_csum_field(ip4h->protocol, txporthdr);
    66	
    67		if (!csum_field)
    68			return -EPROTONOSUPPORT;
    69	
    70		/* RFC 768 - Skip IPv4 UDP packets where sender checksum field is 0 */
    71		if (*csum_field == 0 && ip4h->protocol == IPPROTO_UDP)
    72			return 0;
    73	
  > 74		csum_value = ~ntohs(csum_trailer->csum_value);
  > 75		ip_hdr_csum = ~ip_fast_csum(ip4h, (int)ip4h->ihl);
  > 76		ip_payload_csum = csum16_sub(csum_value, ip_hdr_csum);
    77	
  > 78		pseudo_csum = ~ntohs(csum_tcpudp_magic(ip4h->saddr, ip4h->daddr,
    79				     (u16)(ntohs(ip4h->tot_len) - ip4h->ihl * 4),
    80				     (u16)ip4h->protocol, 0));
  > 81		ip_pseudo_payload_csum = csum16_add(ip_payload_csum, pseudo_csum);
    82	
  > 83		csum_value_final = ~csum16_sub(ip_pseudo_payload_csum,
  > 84					       ntohs(*csum_field));
    85	
    86		if (unlikely(csum_value_final == 0)) {
    87			switch (ip4h->protocol) {
    88			case IPPROTO_UDP:
    89				/* RFC 768 - DL4 1's complement rule for UDP csum 0 */
    90				csum_value_final = ~csum_value_final;
    91				break;
    92	
    93			case IPPROTO_TCP:
    94				/* DL4 Non-RFC compliant TCP checksum found */
    95				if (*csum_field == 0xFFFF)
    96					csum_value_final = ~csum_value_final;
    97				break;
    98			}
    99		}
   100	
   101		if (csum_value_final == ntohs(*csum_field))
   102			return 0;
   103		else
   104			return -EINVAL;
   105	}
   106	
   107	#if IS_ENABLED(CONFIG_IPV6)
   108	static int
   109	rmnet_map_ipv6_dl_csum_trailer(struct sk_buff *skb,
   110				       struct rmnet_map_dl_csum_trailer *csum_trailer)
   111	{
   112		u16 ip_pseudo_payload_csum, pseudo_csum, ip6_hdr_csum, *csum_field;
   113		u16 csum_value, ip6_payload_csum, csum_value_final;
   114		struct ipv6hdr *ip6h;
   115		void *txporthdr;
   116		u32 length;
   117	
   118		ip6h = (struct ipv6hdr *)(skb->data);
   119	
   120		txporthdr = skb->data + sizeof(struct ipv6hdr);
   121		csum_field = rmnet_map_get_csum_field(ip6h->nexthdr, txporthdr);
   122	
   123		if (!csum_field)
   124			return -EPROTONOSUPPORT;
   125	
   126		csum_value = ~ntohs(csum_trailer->csum_value);
 > 127		ip6_hdr_csum = ~ntohs(ip_compute_csum(ip6h,
   128				      (int)(txporthdr - (void *)(skb->data))));
 > 129		ip6_payload_csum = csum16_sub(csum_value, ip6_hdr_csum);
   130	
   131		length = (ip6h->nexthdr == IPPROTO_UDP) ?
   132			 ntohs(((struct udphdr *)txporthdr)->len) :
   133			 ntohs(ip6h->payload_len);
   134		pseudo_csum = ~ntohs(csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
   135				     length, ip6h->nexthdr, 0));
   136		ip_pseudo_payload_csum = csum16_add(ip6_payload_csum, pseudo_csum);
   137	
   138		csum_value_final = ~csum16_sub(ip_pseudo_payload_csum,
   139					       ntohs(*csum_field));
   140	
   141		if (unlikely(csum_value_final == 0)) {
   142			switch (ip6h->nexthdr) {
   143			case IPPROTO_UDP:
   144				/* RFC 2460 section 8.1
   145				 * DL6 One's complement rule for UDP checksum 0
   146				 */
   147				csum_value_final = ~csum_value_final;
   148				break;
   149	
   150			case IPPROTO_TCP:
   151				/* DL6 Non-RFC compliant TCP checksum found */
   152				if (*csum_field == 0xFFFF)
   153					csum_value_final = ~csum_value_final;
   154				break;
   155			}
   156		}
   157	
   158		if (csum_value_final == ntohs(*csum_field))
   159			return 0;
   160		else
   161			return -EINVAL;
   162	}
   163	#endif
   164	

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation