datapath/checksum.h

   1 /*
   2  * Copyright (c) 2010, 2011 Nicira Networks.
   3  * Distributed under the terms of the GNU GPL version 2.
   4  *
   5  * Significant portions of this file may be copied from parts of the Linux
   6  * kernel, by Linus Torvalds and others.
   7  */
   8
   9 #ifndef CHECKSUM_H
  10 #define CHECKSUM_H 1
  11
  12 #include <linux/skbuff.h>
  13 #include <linux/version.h>
  14
  15 #include <net/checksum.h>
  16
  17 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,22) || \
  18         (defined(CONFIG_XEN) && defined(HAVE_PROTO_DATA_VALID))
  19 #define NEED_CSUM_NORMALIZE
  20 #endif
  21
  22 /* These are the same values as the checksum constants in 2.6.22+. */
  23 enum csum_type {
  24         OVS_CSUM_NONE = 0,
  25         OVS_CSUM_UNNECESSARY = 1,
  26         OVS_CSUM_COMPLETE = 2,
  27         OVS_CSUM_PARTIAL = 3,
  28 };
  29
  30 #ifdef NEED_CSUM_NORMALIZE
  31 int compute_ip_summed(struct sk_buff *skb, bool xmit);
  32 void forward_ip_summed(struct sk_buff *skb, bool xmit);
  33 u8 get_ip_summed(struct sk_buff *skb);
  34 void set_ip_summed(struct sk_buff *skb, u8 ip_summed);
  35 void get_skb_csum_pointers(const struct sk_buff *skb, u16 *csum_start,
  36                            u16 *csum_offset);
  37 void set_skb_csum_pointers(struct sk_buff *skb, u16 csum_start,
  38                            u16 csum_offset);
  39 #else
  40 static inline int compute_ip_summed(struct sk_buff *skb, bool xmit)
  41 {
  42         return 0;
  43 }
  44
  45 static inline void forward_ip_summed(struct sk_buff *skb, bool xmit) { }
  46
  47 static inline u8 get_ip_summed(struct sk_buff *skb)
  48 {
  49         return skb->ip_summed;
  50 }
  51
  52 static inline void set_ip_summed(struct sk_buff *skb, u8 ip_summed)
  53 {
  54         skb->ip_summed = ip_summed;
  55 }
  56
  57 static inline void get_skb_csum_pointers(const struct sk_buff *skb,
  58                                          u16 *csum_start, u16 *csum_offset)
  59 {
  60         *csum_start = skb->csum_start;
  61         *csum_offset = skb->csum_offset;
  62 }
  63
  64 static inline void set_skb_csum_pointers(struct sk_buff *skb, u16 csum_start,
  65                                          u16 csum_offset)
  66 {
  67         skb->csum_start = csum_start;
  68         skb->csum_offset = csum_offset;
  69 }
  70 #endif
  71
  72 /* This is really compatibility code that belongs in the compat directory.
  73  * However, it needs access to our normalized checksum values, so put it here.
  74  */
  75 #if defined(NEED_CSUM_NORMALIZE) || LINUX_VERSION_CODE < KERNEL_VERSION(2,6,25)
  76 #define inet_proto_csum_replace4 rpl_inet_proto_csum_replace4
  77 static inline void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
  78                                             __be32 from, __be32 to,
  79                                             int pseudohdr)
  80 {
  81         __be32 diff[] = { ~from, to };
  82
  83         if (get_ip_summed(skb) != OVS_CSUM_PARTIAL) {
  84                 *sum = csum_fold(csum_partial((char *)diff, sizeof(diff),
  85                                 ~csum_unfold(*sum)));
  86                 if (get_ip_summed(skb) == OVS_CSUM_COMPLETE && pseudohdr)
  87                         skb->csum = ~csum_partial((char *)diff, sizeof(diff),
  88                                                 ~skb->csum);
  89         } else if (pseudohdr)
  90                 *sum = ~csum_fold(csum_partial((char *)diff, sizeof(diff),
  91                                 csum_unfold(*sum)));
  92 }
  93 #endif
  94
  95 #ifdef NEED_CSUM_NORMALIZE
  96 static inline void update_csum_start(struct sk_buff *skb, int delta)
  97 {
  98         if (get_ip_summed(skb) == OVS_CSUM_PARTIAL) {
  99                 u16 csum_start, csum_offset;
 100
 101                 get_skb_csum_pointers(skb, &csum_start, &csum_offset);
 102                 set_skb_csum_pointers(skb, csum_start + delta, csum_offset);
 103         }
 104 }
 105
 106 static inline int rpl_pskb_expand_head(struct sk_buff *skb, int nhead,
 107                                        int ntail, gfp_t gfp_mask)
 108 {
 109         int err;
 110         int old_headroom = skb_headroom(skb);
 111
 112         err = pskb_expand_head(skb, nhead, ntail, gfp_mask);
 113         if (unlikely(err))
 114                 return err;
 115
 116         update_csum_start(skb, skb_headroom(skb) - old_headroom);
 117
 118         return 0;
 119 }
 120 #define pskb_expand_head rpl_pskb_expand_head
 121
 122 static inline unsigned char *rpl__pskb_pull_tail(struct sk_buff *skb,
 123                                                   int delta)
 124 {
 125         unsigned char *ret;
 126         int old_headroom = skb_headroom(skb);
 127
 128         ret = __pskb_pull_tail(skb, delta);
 129         if (unlikely(!ret))
 130                 return ret;
 131
 132         update_csum_start(skb, skb_headroom(skb) - old_headroom);
 133
 134         return ret;
 135 }
 136 #define __pskb_pull_tail rpl__pskb_pull_tail
 137 #endif
 138
 139 #endif /* checksum.h */