net/core/gro.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 #include <net/gro.h>
   3 #include <net/dst_metadata.h>
   4 #include <net/busy_poll.h>
   5 #include <trace/events/net.h>
   6
   7 #define MAX_GRO_SKBS 8
   8
   9 /* This should be increased if a protocol with a bigger head is added. */
  10 #define GRO_MAX_HEAD (MAX_HEADER + 128)
  11
  12 static DEFINE_SPINLOCK(offload_lock);
  13 static struct list_head offload_base __read_mostly = LIST_HEAD_INIT(offload_base);
  14 /* Maximum number of GRO_NORMAL skbs to batch up for list-RX */
  15 int gro_normal_batch __read_mostly = 8;
  16
  17 /**
  18  *      dev_add_offload - register offload handlers
  19  *      @po: protocol offload declaration
  20  *
  21  *      Add protocol offload handlers to the networking stack. The passed
  22  *      &proto_offload is linked into kernel lists and may not be freed until
  23  *      it has been removed from the kernel lists.
  24  *
  25  *      This call does not sleep therefore it can not
  26  *      guarantee all CPU's that are in middle of receiving packets
  27  *      will see the new offload handlers (until the next received packet).
  28  */
  29 void dev_add_offload(struct packet_offload *po)
  30 {
  31         struct packet_offload *elem;
  32
  33         spin_lock(&offload_lock);
  34         list_for_each_entry(elem, &offload_base, list) {
  35                 if (po->priority < elem->priority)
  36                         break;
  37         }
  38         list_add_rcu(&po->list, elem->list.prev);
  39         spin_unlock(&offload_lock);
  40 }
  41 EXPORT_SYMBOL(dev_add_offload);
  42
  43 /**
  44  *      __dev_remove_offload     - remove offload handler
  45  *      @po: packet offload declaration
  46  *
  47  *      Remove a protocol offload handler that was previously added to the
  48  *      kernel offload handlers by dev_add_offload(). The passed &offload_type
  49  *      is removed from the kernel lists and can be freed or reused once this
  50  *      function returns.
  51  *
  52  *      The packet type might still be in use by receivers
  53  *      and must not be freed until after all the CPU's have gone
  54  *      through a quiescent state.
  55  */
  56 static void __dev_remove_offload(struct packet_offload *po)
  57 {
  58         struct list_head *head = &offload_base;
  59         struct packet_offload *po1;
  60
  61         spin_lock(&offload_lock);
  62
  63         list_for_each_entry(po1, head, list) {
  64                 if (po == po1) {
  65                         list_del_rcu(&po->list);
  66                         goto out;
  67                 }
  68         }
  69
  70         pr_warn("dev_remove_offload: %p not found\n", po);
  71 out:
  72         spin_unlock(&offload_lock);
  73 }
  74
  75 /**
  76  *      dev_remove_offload       - remove packet offload handler
  77  *      @po: packet offload declaration
  78  *
  79  *      Remove a packet offload handler that was previously added to the kernel
  80  *      offload handlers by dev_add_offload(). The passed &offload_type is
  81  *      removed from the kernel lists and can be freed or reused once this
  82  *      function returns.
  83  *
  84  *      This call sleeps to guarantee that no CPU is looking at the packet
  85  *      type after return.
  86  */
  87 void dev_remove_offload(struct packet_offload *po)
  88 {
  89         __dev_remove_offload(po);
  90
  91         synchronize_net();
  92 }
  93 EXPORT_SYMBOL(dev_remove_offload);
  94
  95 /**
  96  *      skb_eth_gso_segment - segmentation handler for ethernet protocols.
  97  *      @skb: buffer to segment
  98  *      @features: features for the output path (see dev->features)
  99  *      @type: Ethernet Protocol ID
 100  */
 101 struct sk_buff *skb_eth_gso_segment(struct sk_buff *skb,
 102                                     netdev_features_t features, __be16 type)
 103 {
 104         struct sk_buff *segs = ERR_PTR(-EPROTONOSUPPORT);
 105         struct packet_offload *ptype;
 106
 107         rcu_read_lock();
 108         list_for_each_entry_rcu(ptype, &offload_base, list) {
 109                 if (ptype->type == type && ptype->callbacks.gso_segment) {
 110                         segs = ptype->callbacks.gso_segment(skb, features);
 111                         break;
 112                 }
 113         }
 114         rcu_read_unlock();
 115
 116         return segs;
 117 }
 118 EXPORT_SYMBOL(skb_eth_gso_segment);
 119
 120 /**
 121  *      skb_mac_gso_segment - mac layer segmentation handler.
 122  *      @skb: buffer to segment
 123  *      @features: features for the output path (see dev->features)
 124  */
 125 struct sk_buff *skb_mac_gso_segment(struct sk_buff *skb,
 126                                     netdev_features_t features)
 127 {
 128         struct sk_buff *segs = ERR_PTR(-EPROTONOSUPPORT);
 129         struct packet_offload *ptype;
 130         int vlan_depth = skb->mac_len;
 131         __be16 type = skb_network_protocol(skb, &vlan_depth);
 132
 133         if (unlikely(!type))
 134                 return ERR_PTR(-EINVAL);
 135
 136         __skb_pull(skb, vlan_depth);
 137
 138         rcu_read_lock();
 139         list_for_each_entry_rcu(ptype, &offload_base, list) {
 140                 if (ptype->type == type && ptype->callbacks.gso_segment) {
 141                         segs = ptype->callbacks.gso_segment(skb, features);
 142                         break;
 143                 }
 144         }
 145         rcu_read_unlock();
 146
 147         __skb_push(skb, skb->data - skb_mac_header(skb));
 148
 149         return segs;
 150 }
 151 EXPORT_SYMBOL(skb_mac_gso_segment);
 152
 153 int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb)
 154 {
 155         struct skb_shared_info *pinfo, *skbinfo = skb_shinfo(skb);
 156         unsigned int offset = skb_gro_offset(skb);
 157         unsigned int headlen = skb_headlen(skb);
 158         unsigned int len = skb_gro_len(skb);
 159         unsigned int delta_truesize;
 160         unsigned int gro_max_size;
 161         unsigned int new_truesize;
 162         struct sk_buff *lp;
 163
 164         /* pairs with WRITE_ONCE() in netif_set_gro_max_size() */
 165         gro_max_size = READ_ONCE(p->dev->gro_max_size);
 166
 167         if (unlikely(p->len + len >= gro_max_size || NAPI_GRO_CB(skb)->flush))
 168                 return -E2BIG;
 169
 170         lp = NAPI_GRO_CB(p)->last;
 171         pinfo = skb_shinfo(lp);
 172
 173         if (headlen <= offset) {
 174                 skb_frag_t *frag;
 175                 skb_frag_t *frag2;
 176                 int i = skbinfo->nr_frags;
 177                 int nr_frags = pinfo->nr_frags + i;
 178
 179                 if (nr_frags > MAX_SKB_FRAGS)
 180                         goto merge;
 181
 182                 offset -= headlen;
 183                 pinfo->nr_frags = nr_frags;
 184                 skbinfo->nr_frags = 0;
 185
 186                 frag = pinfo->frags + nr_frags;
 187                 frag2 = skbinfo->frags + i;
 188                 do {
 189                         *--frag = *--frag2;
 190                 } while (--i);
 191
 192                 skb_frag_off_add(frag, offset);
 193                 skb_frag_size_sub(frag, offset);
 194
 195                 /* all fragments truesize : remove (head size + sk_buff) */
 196                 new_truesize = SKB_TRUESIZE(skb_end_offset(skb));
 197                 delta_truesize = skb->truesize - new_truesize;
 198
 199                 skb->truesize = new_truesize;
 200                 skb->len -= skb->data_len;
 201                 skb->data_len = 0;
 202
 203                 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE;
 204                 goto done;
 205         } else if (skb->head_frag) {
 206                 int nr_frags = pinfo->nr_frags;
 207                 skb_frag_t *frag = pinfo->frags + nr_frags;
 208                 struct page *page = virt_to_head_page(skb->head);
 209                 unsigned int first_size = headlen - offset;
 210                 unsigned int first_offset;
 211
 212                 if (nr_frags + 1 + skbinfo->nr_frags > MAX_SKB_FRAGS)
 213                         goto merge;
 214
 215                 first_offset = skb->data -
 216                                (unsigned char *)page_address(page) +
 217                                offset;
 218
 219                 pinfo->nr_frags = nr_frags + 1 + skbinfo->nr_frags;
 220
 221                 __skb_frag_set_page(frag, page);
 222                 skb_frag_off_set(frag, first_offset);
 223                 skb_frag_size_set(frag, first_size);
 224
 225                 memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags);
 226                 /* We dont need to clear skbinfo->nr_frags here */
 227
 228                 new_truesize = SKB_DATA_ALIGN(sizeof(struct sk_buff));
 229                 delta_truesize = skb->truesize - new_truesize;
 230                 skb->truesize = new_truesize;
 231                 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD;
 232                 goto done;
 233         }
 234
 235 merge:
 236         /* sk owenrship - if any - completely transferred to the aggregated packet */
 237         skb->destructor = NULL;
 238         delta_truesize = skb->truesize;
 239         if (offset > headlen) {
 240                 unsigned int eat = offset - headlen;
 241
 242                 skb_frag_off_add(&skbinfo->frags[0], eat);
 243                 skb_frag_size_sub(&skbinfo->frags[0], eat);
 244                 skb->data_len -= eat;
 245                 skb->len -= eat;
 246                 offset = headlen;
 247         }
 248
 249         __skb_pull(skb, offset);
 250
 251         if (NAPI_GRO_CB(p)->last == p)
 252                 skb_shinfo(p)->frag_list = skb;
 253         else
 254                 NAPI_GRO_CB(p)->last->next = skb;
 255         NAPI_GRO_CB(p)->last = skb;
 256         __skb_header_release(skb);
 257         lp = p;
 258
 259 done:
 260         NAPI_GRO_CB(p)->count++;
 261         p->data_len += len;
 262         p->truesize += delta_truesize;
 263         p->len += len;
 264         if (lp != p) {
 265                 lp->data_len += len;
 266                 lp->truesize += delta_truesize;
 267                 lp->len += len;
 268         }
 269         NAPI_GRO_CB(skb)->same_flow = 1;
 270         return 0;
 271 }
 272
 273
 274 static void napi_gro_complete(struct napi_struct *napi, struct sk_buff *skb)
 275 {
 276         struct packet_offload *ptype;
 277         __be16 type = skb->protocol;
 278         struct list_head *head = &offload_base;
 279         int err = -ENOENT;
 280
 281         BUILD_BUG_ON(sizeof(struct napi_gro_cb) > sizeof(skb->cb));
 282
 283         if (NAPI_GRO_CB(skb)->count == 1) {
 284                 skb_shinfo(skb)->gso_size = 0;
 285                 goto out;
 286         }
 287
 288         rcu_read_lock();
 289         list_for_each_entry_rcu(ptype, head, list) {
 290                 if (ptype->type != type || !ptype->callbacks.gro_complete)
 291                         continue;
 292
 293                 err = INDIRECT_CALL_INET(ptype->callbacks.gro_complete,
 294                                          ipv6_gro_complete, inet_gro_complete,
 295                                          skb, 0);
 296                 break;
 297         }
 298         rcu_read_unlock();
 299
 300         if (err) {
 301                 WARN_ON(&ptype->list == head);
 302                 kfree_skb(skb);
 303                 return;
 304         }
 305
 306 out:
 307         gro_normal_one(napi, skb, NAPI_GRO_CB(skb)->count);
 308 }
 309
 310 static void __napi_gro_flush_chain(struct napi_struct *napi, u32 index,
 311                                    bool flush_old)
 312 {
 313         struct list_head *head = &napi->gro_hash[index].list;
 314         struct sk_buff *skb, *p;
 315
 316         list_for_each_entry_safe_reverse(skb, p, head, list) {
 317                 if (flush_old && NAPI_GRO_CB(skb)->age == jiffies)
 318                         return;
 319                 skb_list_del_init(skb);
 320                 napi_gro_complete(napi, skb);
 321                 napi->gro_hash[index].count--;
 322         }
 323
 324         if (!napi->gro_hash[index].count)
 325                 __clear_bit(index, &napi->gro_bitmask);
 326 }
 327
 328 /* napi->gro_hash[].list contains packets ordered by age.
 329  * youngest packets at the head of it.
 330  * Complete skbs in reverse order to reduce latencies.
 331  */
 332 void napi_gro_flush(struct napi_struct *napi, bool flush_old)
 333 {
 334         unsigned long bitmask = napi->gro_bitmask;
 335         unsigned int i, base = ~0U;
 336
 337         while ((i = ffs(bitmask)) != 0) {
 338                 bitmask >>= i;
 339                 base += i;
 340                 __napi_gro_flush_chain(napi, base, flush_old);
 341         }
 342 }
 343 EXPORT_SYMBOL(napi_gro_flush);
 344
 345 static void gro_list_prepare(const struct list_head *head,
 346                              const struct sk_buff *skb)
 347 {
 348         unsigned int maclen = skb->dev->hard_header_len;
 349         u32 hash = skb_get_hash_raw(skb);
 350         struct sk_buff *p;
 351
 352         list_for_each_entry(p, head, list) {
 353                 unsigned long diffs;
 354
 355                 NAPI_GRO_CB(p)->flush = 0;
 356
 357                 if (hash != skb_get_hash_raw(p)) {
 358                         NAPI_GRO_CB(p)->same_flow = 0;
 359                         continue;
 360                 }
 361
 362                 diffs = (unsigned long)p->dev ^ (unsigned long)skb->dev;
 363                 diffs |= skb_vlan_tag_present(p) ^ skb_vlan_tag_present(skb);
 364                 if (skb_vlan_tag_present(p))
 365                         diffs |= skb_vlan_tag_get(p) ^ skb_vlan_tag_get(skb);
 366                 diffs |= skb_metadata_differs(p, skb);
 367                 if (maclen == ETH_HLEN)
 368                         diffs |= compare_ether_header(skb_mac_header(p),
 369                                                       skb_mac_header(skb));
 370                 else if (!diffs)
 371                         diffs = memcmp(skb_mac_header(p),
 372                                        skb_mac_header(skb),
 373                                        maclen);
 374
 375                 /* in most common scenarions 'slow_gro' is 0
 376                  * otherwise we are already on some slower paths
 377                  * either skip all the infrequent tests altogether or
 378                  * avoid trying too hard to skip each of them individually
 379                  */
 380                 if (!diffs && unlikely(skb->slow_gro | p->slow_gro)) {
 381 #if IS_ENABLED(CONFIG_SKB_EXTENSIONS) && IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
 382                         struct tc_skb_ext *skb_ext;
 383                         struct tc_skb_ext *p_ext;
 384 #endif
 385
 386                         diffs |= p->sk != skb->sk;
 387                         diffs |= skb_metadata_dst_cmp(p, skb);
 388                         diffs |= skb_get_nfct(p) ^ skb_get_nfct(skb);
 389
 390 #if IS_ENABLED(CONFIG_SKB_EXTENSIONS) && IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
 391                         skb_ext = skb_ext_find(skb, TC_SKB_EXT);
 392                         p_ext = skb_ext_find(p, TC_SKB_EXT);
 393
 394                         diffs |= (!!p_ext) ^ (!!skb_ext);
 395                         if (!diffs && unlikely(skb_ext))
 396                                 diffs |= p_ext->chain ^ skb_ext->chain;
 397 #endif
 398                 }
 399
 400                 NAPI_GRO_CB(p)->same_flow = !diffs;
 401         }
 402 }
 403
 404 static inline void skb_gro_reset_offset(struct sk_buff *skb, u32 nhoff)
 405 {
 406         const struct skb_shared_info *pinfo = skb_shinfo(skb);
 407         const skb_frag_t *frag0 = &pinfo->frags[0];
 408
 409         NAPI_GRO_CB(skb)->data_offset = 0;
 410         NAPI_GRO_CB(skb)->frag0 = NULL;
 411         NAPI_GRO_CB(skb)->frag0_len = 0;
 412
 413         if (!skb_headlen(skb) && pinfo->nr_frags &&
 414             !PageHighMem(skb_frag_page(frag0)) &&
 415             (!NET_IP_ALIGN || !((skb_frag_off(frag0) + nhoff) & 3))) {
 416                 NAPI_GRO_CB(skb)->frag0 = skb_frag_address(frag0);
 417                 NAPI_GRO_CB(skb)->frag0_len = min_t(unsigned int,
 418                                                     skb_frag_size(frag0),
 419                                                     skb->end - skb->tail);
 420         }
 421 }
 422
 423 static void gro_pull_from_frag0(struct sk_buff *skb, int grow)
 424 {
 425         struct skb_shared_info *pinfo = skb_shinfo(skb);
 426
 427         BUG_ON(skb->end - skb->tail < grow);
 428
 429         memcpy(skb_tail_pointer(skb), NAPI_GRO_CB(skb)->frag0, grow);
 430
 431         skb->data_len -= grow;
 432         skb->tail += grow;
 433
 434         skb_frag_off_add(&pinfo->frags[0], grow);
 435         skb_frag_size_sub(&pinfo->frags[0], grow);
 436
 437         if (unlikely(!skb_frag_size(&pinfo->frags[0]))) {
 438                 skb_frag_unref(skb, 0);
 439                 memmove(pinfo->frags, pinfo->frags + 1,
 440                         --pinfo->nr_frags * sizeof(pinfo->frags[0]));
 441         }
 442 }
 443
 444 static void gro_flush_oldest(struct napi_struct *napi, struct list_head *head)
 445 {
 446         struct sk_buff *oldest;
 447
 448         oldest = list_last_entry(head, struct sk_buff, list);
 449
 450         /* We are called with head length >= MAX_GRO_SKBS, so this is
 451          * impossible.
 452          */
 453         if (WARN_ON_ONCE(!oldest))
 454                 return;
 455
 456         /* Do not adjust napi->gro_hash[].count, caller is adding a new
 457          * SKB to the chain.
 458          */
 459         skb_list_del_init(oldest);
 460         napi_gro_complete(napi, oldest);
 461 }
 462
 463 static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
 464 {
 465         u32 bucket = skb_get_hash_raw(skb) & (GRO_HASH_BUCKETS - 1);
 466         struct gro_list *gro_list = &napi->gro_hash[bucket];
 467         struct list_head *head = &offload_base;
 468         struct packet_offload *ptype;
 469         __be16 type = skb->protocol;
 470         struct sk_buff *pp = NULL;
 471         enum gro_result ret;
 472         int same_flow;
 473         int grow;
 474
 475         if (netif_elide_gro(skb->dev))
 476                 goto normal;
 477
 478         gro_list_prepare(&gro_list->list, skb);
 479
 480         rcu_read_lock();
 481         list_for_each_entry_rcu(ptype, head, list) {
 482                 if (ptype->type != type || !ptype->callbacks.gro_receive)
 483                         continue;
 484
 485                 skb_set_network_header(skb, skb_gro_offset(skb));
 486                 skb_reset_mac_len(skb);
 487                 BUILD_BUG_ON(sizeof_field(struct napi_gro_cb, zeroed) != sizeof(u32));
 488                 BUILD_BUG_ON(!IS_ALIGNED(offsetof(struct napi_gro_cb, zeroed),
 489                                          sizeof(u32))); /* Avoid slow unaligned acc */
 490                 *(u32 *)&NAPI_GRO_CB(skb)->zeroed = 0;
 491                 NAPI_GRO_CB(skb)->flush = skb_is_gso(skb) || skb_has_frag_list(skb);
 492                 NAPI_GRO_CB(skb)->is_atomic = 1;
 493
 494                 /* Setup for GRO checksum validation */
 495                 switch (skb->ip_summed) {
 496                 case CHECKSUM_COMPLETE:
 497                         NAPI_GRO_CB(skb)->csum = skb->csum;
 498                         NAPI_GRO_CB(skb)->csum_valid = 1;
 499                         break;
 500                 case CHECKSUM_UNNECESSARY:
 501                         NAPI_GRO_CB(skb)->csum_cnt = skb->csum_level + 1;
 502                         break;
 503                 }
 504
 505                 pp = INDIRECT_CALL_INET(ptype->callbacks.gro_receive,
 506                                         ipv6_gro_receive, inet_gro_receive,
 507                                         &gro_list->list, skb);
 508                 break;
 509         }
 510         rcu_read_unlock();
 511
 512         if (&ptype->list == head)
 513                 goto normal;
 514
 515         if (PTR_ERR(pp) == -EINPROGRESS) {
 516                 ret = GRO_CONSUMED;
 517                 goto ok;
 518         }
 519
 520         same_flow = NAPI_GRO_CB(skb)->same_flow;
 521         ret = NAPI_GRO_CB(skb)->free ? GRO_MERGED_FREE : GRO_MERGED;
 522
 523         if (pp) {
 524                 skb_list_del_init(pp);
 525                 napi_gro_complete(napi, pp);
 526                 gro_list->count--;
 527         }
 528
 529         if (same_flow)
 530                 goto ok;
 531
 532         if (NAPI_GRO_CB(skb)->flush)
 533                 goto normal;
 534
 535         if (unlikely(gro_list->count >= MAX_GRO_SKBS))
 536                 gro_flush_oldest(napi, &gro_list->list);
 537         else
 538                 gro_list->count++;
 539
 540         NAPI_GRO_CB(skb)->count = 1;
 541         NAPI_GRO_CB(skb)->age = jiffies;
 542         NAPI_GRO_CB(skb)->last = skb;
 543         skb_shinfo(skb)->gso_size = skb_gro_len(skb);
 544         list_add(&skb->list, &gro_list->list);
 545         ret = GRO_HELD;
 546
 547 pull:
 548         grow = skb_gro_offset(skb) - skb_headlen(skb);
 549         if (grow > 0)
 550                 gro_pull_from_frag0(skb, grow);
 551 ok:
 552         if (gro_list->count) {
 553                 if (!test_bit(bucket, &napi->gro_bitmask))
 554                         __set_bit(bucket, &napi->gro_bitmask);
 555         } else if (test_bit(bucket, &napi->gro_bitmask)) {
 556                 __clear_bit(bucket, &napi->gro_bitmask);
 557         }
 558
 559         return ret;
 560
 561 normal:
 562         ret = GRO_NORMAL;
 563         goto pull;
 564 }
 565
 566 struct packet_offload *gro_find_receive_by_type(__be16 type)
 567 {
 568         struct list_head *offload_head = &offload_base;
 569         struct packet_offload *ptype;
 570
 571         list_for_each_entry_rcu(ptype, offload_head, list) {
 572                 if (ptype->type != type || !ptype->callbacks.gro_receive)
 573                         continue;
 574                 return ptype;
 575         }
 576         return NULL;
 577 }
 578 EXPORT_SYMBOL(gro_find_receive_by_type);
 579
 580 struct packet_offload *gro_find_complete_by_type(__be16 type)
 581 {
 582         struct list_head *offload_head = &offload_base;
 583         struct packet_offload *ptype;
 584
 585         list_for_each_entry_rcu(ptype, offload_head, list) {
 586                 if (ptype->type != type || !ptype->callbacks.gro_complete)
 587                         continue;
 588                 return ptype;
 589         }
 590         return NULL;
 591 }
 592 EXPORT_SYMBOL(gro_find_complete_by_type);
 593
 594 static gro_result_t napi_skb_finish(struct napi_struct *napi,
 595                                     struct sk_buff *skb,
 596                                     gro_result_t ret)
 597 {
 598         switch (ret) {
 599         case GRO_NORMAL:
 600                 gro_normal_one(napi, skb, 1);
 601                 break;
 602
 603         case GRO_MERGED_FREE:
 604                 if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
 605                         napi_skb_free_stolen_head(skb);
 606                 else if (skb->fclone != SKB_FCLONE_UNAVAILABLE)
 607                         __kfree_skb(skb);
 608                 else
 609                         __kfree_skb_defer(skb);
 610                 break;
 611
 612         case GRO_HELD:
 613         case GRO_MERGED:
 614         case GRO_CONSUMED:
 615                 break;
 616         }
 617
 618         return ret;
 619 }
 620
 621 gro_result_t napi_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
 622 {
 623         gro_result_t ret;
 624
 625         skb_mark_napi_id(skb, napi);
 626         trace_napi_gro_receive_entry(skb);
 627
 628         skb_gro_reset_offset(skb, 0);
 629
 630         ret = napi_skb_finish(napi, skb, dev_gro_receive(napi, skb));
 631         trace_napi_gro_receive_exit(ret);
 632
 633         return ret;
 634 }
 635 EXPORT_SYMBOL(napi_gro_receive);
 636
 637 static void napi_reuse_skb(struct napi_struct *napi, struct sk_buff *skb)
 638 {
 639         if (unlikely(skb->pfmemalloc)) {
 640                 consume_skb(skb);
 641                 return;
 642         }
 643         __skb_pull(skb, skb_headlen(skb));
 644         /* restore the reserve we had after netdev_alloc_skb_ip_align() */
 645         skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN - skb_headroom(skb));
 646         __vlan_hwaccel_clear_tag(skb);
 647         skb->dev = napi->dev;
 648         skb->skb_iif = 0;
 649
 650         /* eth_type_trans() assumes pkt_type is PACKET_HOST */
 651         skb->pkt_type = PACKET_HOST;
 652
 653         skb->encapsulation = 0;
 654         skb_shinfo(skb)->gso_type = 0;
 655         if (unlikely(skb->slow_gro)) {
 656                 skb_orphan(skb);
 657                 skb_ext_reset(skb);
 658                 nf_reset_ct(skb);
 659                 skb->slow_gro = 0;
 660         }
 661
 662         napi->skb = skb;
 663 }
 664
 665 struct sk_buff *napi_get_frags(struct napi_struct *napi)
 666 {
 667         struct sk_buff *skb = napi->skb;
 668
 669         if (!skb) {
 670                 skb = napi_alloc_skb(napi, GRO_MAX_HEAD);
 671                 if (skb) {
 672                         napi->skb = skb;
 673                         skb_mark_napi_id(skb, napi);
 674                 }
 675         }
 676         return skb;
 677 }
 678 EXPORT_SYMBOL(napi_get_frags);
 679
 680 static gro_result_t napi_frags_finish(struct napi_struct *napi,
 681                                       struct sk_buff *skb,
 682                                       gro_result_t ret)
 683 {
 684         switch (ret) {
 685         case GRO_NORMAL:
 686         case GRO_HELD:
 687                 __skb_push(skb, ETH_HLEN);
 688                 skb->protocol = eth_type_trans(skb, skb->dev);
 689                 if (ret == GRO_NORMAL)
 690                         gro_normal_one(napi, skb, 1);
 691                 break;
 692
 693         case GRO_MERGED_FREE:
 694                 if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
 695                         napi_skb_free_stolen_head(skb);
 696                 else
 697                         napi_reuse_skb(napi, skb);
 698                 break;
 699
 700         case GRO_MERGED:
 701         case GRO_CONSUMED:
 702                 break;
 703         }
 704
 705         return ret;
 706 }
 707
 708 /* Upper GRO stack assumes network header starts at gro_offset=0
 709  * Drivers could call both napi_gro_frags() and napi_gro_receive()
 710  * We copy ethernet header into skb->data to have a common layout.
 711  */
 712 static struct sk_buff *napi_frags_skb(struct napi_struct *napi)
 713 {
 714         struct sk_buff *skb = napi->skb;
 715         const struct ethhdr *eth;
 716         unsigned int hlen = sizeof(*eth);
 717
 718         napi->skb = NULL;
 719
 720         skb_reset_mac_header(skb);
 721         skb_gro_reset_offset(skb, hlen);
 722
 723         if (unlikely(skb_gro_header_hard(skb, hlen))) {
 724                 eth = skb_gro_header_slow(skb, hlen, 0);
 725                 if (unlikely(!eth)) {
 726                         net_warn_ratelimited("%s: dropping impossible skb from %s\n",
 727                                              __func__, napi->dev->name);
 728                         napi_reuse_skb(napi, skb);
 729                         return NULL;
 730                 }
 731         } else {
 732                 eth = (const struct ethhdr *)skb->data;
 733                 gro_pull_from_frag0(skb, hlen);
 734                 NAPI_GRO_CB(skb)->frag0 += hlen;
 735                 NAPI_GRO_CB(skb)->frag0_len -= hlen;
 736         }
 737         __skb_pull(skb, hlen);
 738
 739         /*
 740          * This works because the only protocols we care about don't require
 741          * special handling.
 742          * We'll fix it up properly in napi_frags_finish()
 743          */
 744         skb->protocol = eth->h_proto;
 745
 746         return skb;
 747 }
 748
 749 gro_result_t napi_gro_frags(struct napi_struct *napi)
 750 {
 751         gro_result_t ret;
 752         struct sk_buff *skb = napi_frags_skb(napi);
 753
 754         trace_napi_gro_frags_entry(skb);
 755
 756         ret = napi_frags_finish(napi, skb, dev_gro_receive(napi, skb));
 757         trace_napi_gro_frags_exit(ret);
 758
 759         return ret;
 760 }
 761 EXPORT_SYMBOL(napi_gro_frags);
 762
 763 /* Compute the checksum from gro_offset and return the folded value
 764  * after adding in any pseudo checksum.
 765  */
 766 __sum16 __skb_gro_checksum_complete(struct sk_buff *skb)
 767 {
 768         __wsum wsum;
 769         __sum16 sum;
 770
 771         wsum = skb_checksum(skb, skb_gro_offset(skb), skb_gro_len(skb), 0);
 772
 773         /* NAPI_GRO_CB(skb)->csum holds pseudo checksum */
 774         sum = csum_fold(csum_add(NAPI_GRO_CB(skb)->csum, wsum));
 775         /* See comments in __skb_checksum_complete(). */
 776         if (likely(!sum)) {
 777                 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
 778                     !skb->csum_complete_sw)
 779                         netdev_rx_csum_fault(skb->dev, skb);
 780         }
 781
 782         NAPI_GRO_CB(skb)->csum = wsum;
 783         NAPI_GRO_CB(skb)->csum_valid = 1;
 784
 785         return sum;
 786 }
 787 EXPORT_SYMBOL(__skb_gro_checksum_complete);