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