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         int segs;
 164
 165         /* pairs with WRITE_ONCE() in netif_set_gro_max_size() */
 166         gro_max_size = READ_ONCE(p->dev->gro_max_size);
 167
 168         if (unlikely(p->len + len >= gro_max_size || NAPI_GRO_CB(skb)->flush))
 169                 return -E2BIG;
 170
 171         if (unlikely(p->len + len >= GRO_LEGACY_MAX_SIZE)) {
 172                 if (p->protocol != htons(ETH_P_IPV6) ||
 173                     skb_headroom(p) < sizeof(struct hop_jumbo_hdr) ||
 174                     ipv6_hdr(p)->nexthdr != IPPROTO_TCP ||
 175                     p->encapsulation)
 176                         return -E2BIG;
 177         }
 178
 179         segs = NAPI_GRO_CB(skb)->count;
 180         lp = NAPI_GRO_CB(p)->last;
 181         pinfo = skb_shinfo(lp);
 182
 183         if (headlen <= offset) {
 184                 skb_frag_t *frag;
 185                 skb_frag_t *frag2;
 186                 int i = skbinfo->nr_frags;
 187                 int nr_frags = pinfo->nr_frags + i;
 188
 189                 if (nr_frags > MAX_SKB_FRAGS)
 190                         goto merge;
 191
 192                 offset -= headlen;
 193                 pinfo->nr_frags = nr_frags;
 194                 skbinfo->nr_frags = 0;
 195
 196                 frag = pinfo->frags + nr_frags;
 197                 frag2 = skbinfo->frags + i;
 198                 do {
 199                         *--frag = *--frag2;
 200                 } while (--i);
 201
 202                 skb_frag_off_add(frag, offset);
 203                 skb_frag_size_sub(frag, offset);
 204
 205                 /* all fragments truesize : remove (head size + sk_buff) */
 206                 new_truesize = SKB_TRUESIZE(skb_end_offset(skb));
 207                 delta_truesize = skb->truesize - new_truesize;
 208
 209                 skb->truesize = new_truesize;
 210                 skb->len -= skb->data_len;
 211                 skb->data_len = 0;
 212
 213                 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE;
 214                 goto done;
 215         } else if (skb->head_frag) {
 216                 int nr_frags = pinfo->nr_frags;
 217                 skb_frag_t *frag = pinfo->frags + nr_frags;
 218                 struct page *page = virt_to_head_page(skb->head);
 219                 unsigned int first_size = headlen - offset;
 220                 unsigned int first_offset;
 221
 222                 if (nr_frags + 1 + skbinfo->nr_frags > MAX_SKB_FRAGS)
 223                         goto merge;
 224
 225                 first_offset = skb->data -
 226                                (unsigned char *)page_address(page) +
 227                                offset;
 228
 229                 pinfo->nr_frags = nr_frags + 1 + skbinfo->nr_frags;
 230
 231                 __skb_frag_set_page(frag, page);
 232                 skb_frag_off_set(frag, first_offset);
 233                 skb_frag_size_set(frag, first_size);
 234
 235                 memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags);
 236                 /* We dont need to clear skbinfo->nr_frags here */
 237
 238                 new_truesize = SKB_DATA_ALIGN(sizeof(struct sk_buff));
 239                 delta_truesize = skb->truesize - new_truesize;
 240                 skb->truesize = new_truesize;
 241                 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD;
 242                 goto done;
 243         }
 244
 245 merge:
 246         /* sk owenrship - if any - completely transferred to the aggregated packet */
 247         skb->destructor = NULL;
 248         delta_truesize = skb->truesize;
 249         if (offset > headlen) {
 250                 unsigned int eat = offset - headlen;
 251
 252                 skb_frag_off_add(&skbinfo->frags[0], eat);
 253                 skb_frag_size_sub(&skbinfo->frags[0], eat);
 254                 skb->data_len -= eat;
 255                 skb->len -= eat;
 256                 offset = headlen;
 257         }
 258
 259         __skb_pull(skb, offset);
 260
 261         if (NAPI_GRO_CB(p)->last == p)
 262                 skb_shinfo(p)->frag_list = skb;
 263         else
 264                 NAPI_GRO_CB(p)->last->next = skb;
 265         NAPI_GRO_CB(p)->last = skb;
 266         __skb_header_release(skb);
 267         lp = p;
 268
 269 done:
 270         NAPI_GRO_CB(p)->count += segs;
 271         p->data_len += len;
 272         p->truesize += delta_truesize;
 273         p->len += len;
 274         if (lp != p) {
 275                 lp->data_len += len;
 276                 lp->truesize += delta_truesize;
 277                 lp->len += len;
 278         }
 279         NAPI_GRO_CB(skb)->same_flow = 1;
 280         return 0;
 281 }
 282
 283
 284 static void napi_gro_complete(struct napi_struct *napi, struct sk_buff *skb)
 285 {
 286         struct packet_offload *ptype;
 287         __be16 type = skb->protocol;
 288         struct list_head *head = &offload_base;
 289         int err = -ENOENT;
 290
 291         BUILD_BUG_ON(sizeof(struct napi_gro_cb) > sizeof(skb->cb));
 292
 293         if (NAPI_GRO_CB(skb)->count == 1) {
 294                 skb_shinfo(skb)->gso_size = 0;
 295                 goto out;
 296         }
 297
 298         rcu_read_lock();
 299         list_for_each_entry_rcu(ptype, head, list) {
 300                 if (ptype->type != type || !ptype->callbacks.gro_complete)
 301                         continue;
 302
 303                 err = INDIRECT_CALL_INET(ptype->callbacks.gro_complete,
 304                                          ipv6_gro_complete, inet_gro_complete,
 305                                          skb, 0);
 306                 break;
 307         }
 308         rcu_read_unlock();
 309
 310         if (err) {
 311                 WARN_ON(&ptype->list == head);
 312                 kfree_skb(skb);
 313                 return;
 314         }
 315
 316 out:
 317         gro_normal_one(napi, skb, NAPI_GRO_CB(skb)->count);
 318 }
 319
 320 static void __napi_gro_flush_chain(struct napi_struct *napi, u32 index,
 321                                    bool flush_old)
 322 {
 323         struct list_head *head = &napi->gro_hash[index].list;
 324         struct sk_buff *skb, *p;
 325
 326         list_for_each_entry_safe_reverse(skb, p, head, list) {
 327                 if (flush_old && NAPI_GRO_CB(skb)->age == jiffies)
 328                         return;
 329                 skb_list_del_init(skb);
 330                 napi_gro_complete(napi, skb);
 331                 napi->gro_hash[index].count--;
 332         }
 333
 334         if (!napi->gro_hash[index].count)
 335                 __clear_bit(index, &napi->gro_bitmask);
 336 }
 337
 338 /* napi->gro_hash[].list contains packets ordered by age.
 339  * youngest packets at the head of it.
 340  * Complete skbs in reverse order to reduce latencies.
 341  */
 342 void napi_gro_flush(struct napi_struct *napi, bool flush_old)
 343 {
 344         unsigned long bitmask = napi->gro_bitmask;
 345         unsigned int i, base = ~0U;
 346
 347         while ((i = ffs(bitmask)) != 0) {
 348                 bitmask >>= i;
 349                 base += i;
 350                 __napi_gro_flush_chain(napi, base, flush_old);
 351         }
 352 }
 353 EXPORT_SYMBOL(napi_gro_flush);
 354
 355 static void gro_list_prepare(const struct list_head *head,
 356                              const struct sk_buff *skb)
 357 {
 358         unsigned int maclen = skb->dev->hard_header_len;
 359         u32 hash = skb_get_hash_raw(skb);
 360         struct sk_buff *p;
 361
 362         list_for_each_entry(p, head, list) {
 363                 unsigned long diffs;
 364
 365                 NAPI_GRO_CB(p)->flush = 0;
 366
 367                 if (hash != skb_get_hash_raw(p)) {
 368                         NAPI_GRO_CB(p)->same_flow = 0;
 369                         continue;
 370                 }
 371
 372                 diffs = (unsigned long)p->dev ^ (unsigned long)skb->dev;
 373                 diffs |= skb_vlan_tag_present(p) ^ skb_vlan_tag_present(skb);
 374                 if (skb_vlan_tag_present(p))
 375                         diffs |= skb_vlan_tag_get(p) ^ skb_vlan_tag_get(skb);
 376                 diffs |= skb_metadata_differs(p, skb);
 377                 if (maclen == ETH_HLEN)
 378                         diffs |= compare_ether_header(skb_mac_header(p),
 379                                                       skb_mac_header(skb));
 380                 else if (!diffs)
 381                         diffs = memcmp(skb_mac_header(p),
 382                                        skb_mac_header(skb),
 383                                        maclen);
 384
 385                 /* in most common scenarions 'slow_gro' is 0
 386                  * otherwise we are already on some slower paths
 387                  * either skip all the infrequent tests altogether or
 388                  * avoid trying too hard to skip each of them individually
 389                  */
 390                 if (!diffs && unlikely(skb->slow_gro | p->slow_gro)) {
 391 #if IS_ENABLED(CONFIG_SKB_EXTENSIONS) && IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
 392                         struct tc_skb_ext *skb_ext;
 393                         struct tc_skb_ext *p_ext;
 394 #endif
 395
 396                         diffs |= p->sk != skb->sk;
 397                         diffs |= skb_metadata_dst_cmp(p, skb);
 398                         diffs |= skb_get_nfct(p) ^ skb_get_nfct(skb);
 399
 400 #if IS_ENABLED(CONFIG_SKB_EXTENSIONS) && IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
 401                         skb_ext = skb_ext_find(skb, TC_SKB_EXT);
 402                         p_ext = skb_ext_find(p, TC_SKB_EXT);
 403
 404                         diffs |= (!!p_ext) ^ (!!skb_ext);
 405                         if (!diffs && unlikely(skb_ext))
 406                                 diffs |= p_ext->chain ^ skb_ext->chain;
 407 #endif
 408                 }
 409
 410                 NAPI_GRO_CB(p)->same_flow = !diffs;
 411         }
 412 }
 413
 414 static inline void skb_gro_reset_offset(struct sk_buff *skb, u32 nhoff)
 415 {
 416         const struct skb_shared_info *pinfo = skb_shinfo(skb);
 417         const skb_frag_t *frag0 = &pinfo->frags[0];
 418
 419         NAPI_GRO_CB(skb)->data_offset = 0;
 420         NAPI_GRO_CB(skb)->frag0 = NULL;
 421         NAPI_GRO_CB(skb)->frag0_len = 0;
 422
 423         if (!skb_headlen(skb) && pinfo->nr_frags &&
 424             !PageHighMem(skb_frag_page(frag0)) &&
 425             (!NET_IP_ALIGN || !((skb_frag_off(frag0) + nhoff) & 3))) {
 426                 NAPI_GRO_CB(skb)->frag0 = skb_frag_address(frag0);
 427                 NAPI_GRO_CB(skb)->frag0_len = min_t(unsigned int,
 428                                                     skb_frag_size(frag0),
 429                                                     skb->end - skb->tail);
 430         }
 431 }
 432
 433 static void gro_pull_from_frag0(struct sk_buff *skb, int grow)
 434 {
 435         struct skb_shared_info *pinfo = skb_shinfo(skb);
 436
 437         BUG_ON(skb->end - skb->tail < grow);
 438
 439         memcpy(skb_tail_pointer(skb), NAPI_GRO_CB(skb)->frag0, grow);
 440
 441         skb->data_len -= grow;
 442         skb->tail += grow;
 443
 444         skb_frag_off_add(&pinfo->frags[0], grow);
 445         skb_frag_size_sub(&pinfo->frags[0], grow);
 446
 447         if (unlikely(!skb_frag_size(&pinfo->frags[0]))) {
 448                 skb_frag_unref(skb, 0);
 449                 memmove(pinfo->frags, pinfo->frags + 1,
 450                         --pinfo->nr_frags * sizeof(pinfo->frags[0]));
 451         }
 452 }
 453
 454 static void gro_flush_oldest(struct napi_struct *napi, struct list_head *head)
 455 {
 456         struct sk_buff *oldest;
 457
 458         oldest = list_last_entry(head, struct sk_buff, list);
 459
 460         /* We are called with head length >= MAX_GRO_SKBS, so this is
 461          * impossible.
 462          */
 463         if (WARN_ON_ONCE(!oldest))
 464                 return;
 465
 466         /* Do not adjust napi->gro_hash[].count, caller is adding a new
 467          * SKB to the chain.
 468          */
 469         skb_list_del_init(oldest);
 470         napi_gro_complete(napi, oldest);
 471 }
 472
 473 static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
 474 {
 475         u32 bucket = skb_get_hash_raw(skb) & (GRO_HASH_BUCKETS - 1);
 476         struct gro_list *gro_list = &napi->gro_hash[bucket];
 477         struct list_head *head = &offload_base;
 478         struct packet_offload *ptype;
 479         __be16 type = skb->protocol;
 480         struct sk_buff *pp = NULL;
 481         enum gro_result ret;
 482         int same_flow;
 483         int grow;
 484
 485         if (netif_elide_gro(skb->dev))
 486                 goto normal;
 487
 488         gro_list_prepare(&gro_list->list, skb);
 489
 490         rcu_read_lock();
 491         list_for_each_entry_rcu(ptype, head, list) {
 492                 if (ptype->type != type || !ptype->callbacks.gro_receive)
 493                         continue;
 494
 495                 skb_set_network_header(skb, skb_gro_offset(skb));
 496                 skb_reset_mac_len(skb);
 497                 BUILD_BUG_ON(sizeof_field(struct napi_gro_cb, zeroed) != sizeof(u32));
 498                 BUILD_BUG_ON(!IS_ALIGNED(offsetof(struct napi_gro_cb, zeroed),
 499                                          sizeof(u32))); /* Avoid slow unaligned acc */
 500                 *(u32 *)&NAPI_GRO_CB(skb)->zeroed = 0;
 501                 NAPI_GRO_CB(skb)->flush = skb_has_frag_list(skb);
 502                 NAPI_GRO_CB(skb)->is_atomic = 1;
 503                 NAPI_GRO_CB(skb)->count = 1;
 504                 if (unlikely(skb_is_gso(skb))) {
 505                         NAPI_GRO_CB(skb)->count = skb_shinfo(skb)->gso_segs;
 506                         /* Only support TCP at the moment. */
 507                         if (!skb_is_gso_tcp(skb))
 508                                 NAPI_GRO_CB(skb)->flush = 1;
 509                 }
 510
 511                 /* Setup for GRO checksum validation */
 512                 switch (skb->ip_summed) {
 513                 case CHECKSUM_COMPLETE:
 514                         NAPI_GRO_CB(skb)->csum = skb->csum;
 515                         NAPI_GRO_CB(skb)->csum_valid = 1;
 516                         break;
 517                 case CHECKSUM_UNNECESSARY:
 518                         NAPI_GRO_CB(skb)->csum_cnt = skb->csum_level + 1;
 519                         break;
 520                 }
 521
 522                 pp = INDIRECT_CALL_INET(ptype->callbacks.gro_receive,
 523                                         ipv6_gro_receive, inet_gro_receive,
 524                                         &gro_list->list, skb);
 525                 break;
 526         }
 527         rcu_read_unlock();
 528
 529         if (&ptype->list == head)
 530                 goto normal;
 531
 532         if (PTR_ERR(pp) == -EINPROGRESS) {
 533                 ret = GRO_CONSUMED;
 534                 goto ok;
 535         }
 536
 537         same_flow = NAPI_GRO_CB(skb)->same_flow;
 538         ret = NAPI_GRO_CB(skb)->free ? GRO_MERGED_FREE : GRO_MERGED;
 539
 540         if (pp) {
 541                 skb_list_del_init(pp);
 542                 napi_gro_complete(napi, pp);
 543                 gro_list->count--;
 544         }
 545
 546         if (same_flow)
 547                 goto ok;
 548
 549         if (NAPI_GRO_CB(skb)->flush)
 550                 goto normal;
 551
 552         if (unlikely(gro_list->count >= MAX_GRO_SKBS))
 553                 gro_flush_oldest(napi, &gro_list->list);
 554         else
 555                 gro_list->count++;
 556
 557         NAPI_GRO_CB(skb)->age = jiffies;
 558         NAPI_GRO_CB(skb)->last = skb;
 559         if (!skb_is_gso(skb))
 560                 skb_shinfo(skb)->gso_size = skb_gro_len(skb);
 561         list_add(&skb->list, &gro_list->list);
 562         ret = GRO_HELD;
 563
 564 pull:
 565         grow = skb_gro_offset(skb) - skb_headlen(skb);
 566         if (grow > 0)
 567                 gro_pull_from_frag0(skb, grow);
 568 ok:
 569         if (gro_list->count) {
 570                 if (!test_bit(bucket, &napi->gro_bitmask))
 571                         __set_bit(bucket, &napi->gro_bitmask);
 572         } else if (test_bit(bucket, &napi->gro_bitmask)) {
 573                 __clear_bit(bucket, &napi->gro_bitmask);
 574         }
 575
 576         return ret;
 577
 578 normal:
 579         ret = GRO_NORMAL;
 580         goto pull;
 581 }
 582
 583 struct packet_offload *gro_find_receive_by_type(__be16 type)
 584 {
 585         struct list_head *offload_head = &offload_base;
 586         struct packet_offload *ptype;
 587
 588         list_for_each_entry_rcu(ptype, offload_head, list) {
 589                 if (ptype->type != type || !ptype->callbacks.gro_receive)
 590                         continue;
 591                 return ptype;
 592         }
 593         return NULL;
 594 }
 595 EXPORT_SYMBOL(gro_find_receive_by_type);
 596
 597 struct packet_offload *gro_find_complete_by_type(__be16 type)
 598 {
 599         struct list_head *offload_head = &offload_base;
 600         struct packet_offload *ptype;
 601
 602         list_for_each_entry_rcu(ptype, offload_head, list) {
 603                 if (ptype->type != type || !ptype->callbacks.gro_complete)
 604                         continue;
 605                 return ptype;
 606         }
 607         return NULL;
 608 }
 609 EXPORT_SYMBOL(gro_find_complete_by_type);
 610
 611 static gro_result_t napi_skb_finish(struct napi_struct *napi,
 612                                     struct sk_buff *skb,
 613                                     gro_result_t ret)
 614 {
 615         switch (ret) {
 616         case GRO_NORMAL:
 617                 gro_normal_one(napi, skb, 1);
 618                 break;
 619
 620         case GRO_MERGED_FREE:
 621                 if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
 622                         napi_skb_free_stolen_head(skb);
 623                 else if (skb->fclone != SKB_FCLONE_UNAVAILABLE)
 624                         __kfree_skb(skb);
 625                 else
 626                         __kfree_skb_defer(skb);
 627                 break;
 628
 629         case GRO_HELD:
 630         case GRO_MERGED:
 631         case GRO_CONSUMED:
 632                 break;
 633         }
 634
 635         return ret;
 636 }
 637
 638 gro_result_t napi_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
 639 {
 640         gro_result_t ret;
 641
 642         skb_mark_napi_id(skb, napi);
 643         trace_napi_gro_receive_entry(skb);
 644
 645         skb_gro_reset_offset(skb, 0);
 646
 647         ret = napi_skb_finish(napi, skb, dev_gro_receive(napi, skb));
 648         trace_napi_gro_receive_exit(ret);
 649
 650         return ret;
 651 }
 652 EXPORT_SYMBOL(napi_gro_receive);
 653
 654 static void napi_reuse_skb(struct napi_struct *napi, struct sk_buff *skb)
 655 {
 656         if (unlikely(skb->pfmemalloc)) {
 657                 consume_skb(skb);
 658                 return;
 659         }
 660         __skb_pull(skb, skb_headlen(skb));
 661         /* restore the reserve we had after netdev_alloc_skb_ip_align() */
 662         skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN - skb_headroom(skb));
 663         __vlan_hwaccel_clear_tag(skb);
 664         skb->dev = napi->dev;
 665         skb->skb_iif = 0;
 666
 667         /* eth_type_trans() assumes pkt_type is PACKET_HOST */
 668         skb->pkt_type = PACKET_HOST;
 669
 670         skb->encapsulation = 0;
 671         skb_shinfo(skb)->gso_type = 0;
 672         skb_shinfo(skb)->gso_size = 0;
 673         if (unlikely(skb->slow_gro)) {
 674                 skb_orphan(skb);
 675                 skb_ext_reset(skb);
 676                 nf_reset_ct(skb);
 677                 skb->slow_gro = 0;
 678         }
 679
 680         napi->skb = skb;
 681 }
 682
 683 struct sk_buff *napi_get_frags(struct napi_struct *napi)
 684 {
 685         struct sk_buff *skb = napi->skb;
 686
 687         if (!skb) {
 688                 skb = napi_alloc_skb(napi, GRO_MAX_HEAD);
 689                 if (skb) {
 690                         napi->skb = skb;
 691                         skb_mark_napi_id(skb, napi);
 692                 }
 693         }
 694         return skb;
 695 }
 696 EXPORT_SYMBOL(napi_get_frags);
 697
 698 static gro_result_t napi_frags_finish(struct napi_struct *napi,
 699                                       struct sk_buff *skb,
 700                                       gro_result_t ret)
 701 {
 702         switch (ret) {
 703         case GRO_NORMAL:
 704         case GRO_HELD:
 705                 __skb_push(skb, ETH_HLEN);
 706                 skb->protocol = eth_type_trans(skb, skb->dev);
 707                 if (ret == GRO_NORMAL)
 708                         gro_normal_one(napi, skb, 1);
 709                 break;
 710
 711         case GRO_MERGED_FREE:
 712                 if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
 713                         napi_skb_free_stolen_head(skb);
 714                 else
 715                         napi_reuse_skb(napi, skb);
 716                 break;
 717
 718         case GRO_MERGED:
 719         case GRO_CONSUMED:
 720                 break;
 721         }
 722
 723         return ret;
 724 }
 725
 726 /* Upper GRO stack assumes network header starts at gro_offset=0
 727  * Drivers could call both napi_gro_frags() and napi_gro_receive()
 728  * We copy ethernet header into skb->data to have a common layout.
 729  */
 730 static struct sk_buff *napi_frags_skb(struct napi_struct *napi)
 731 {
 732         struct sk_buff *skb = napi->skb;
 733         const struct ethhdr *eth;
 734         unsigned int hlen = sizeof(*eth);
 735
 736         napi->skb = NULL;
 737
 738         skb_reset_mac_header(skb);
 739         skb_gro_reset_offset(skb, hlen);
 740
 741         if (unlikely(skb_gro_header_hard(skb, hlen))) {
 742                 eth = skb_gro_header_slow(skb, hlen, 0);
 743                 if (unlikely(!eth)) {
 744                         net_warn_ratelimited("%s: dropping impossible skb from %s\n",
 745                                              __func__, napi->dev->name);
 746                         napi_reuse_skb(napi, skb);
 747                         return NULL;
 748                 }
 749         } else {
 750                 eth = (const struct ethhdr *)skb->data;
 751                 gro_pull_from_frag0(skb, hlen);
 752                 NAPI_GRO_CB(skb)->frag0 += hlen;
 753                 NAPI_GRO_CB(skb)->frag0_len -= hlen;
 754         }
 755         __skb_pull(skb, hlen);
 756
 757         /*
 758          * This works because the only protocols we care about don't require
 759          * special handling.
 760          * We'll fix it up properly in napi_frags_finish()
 761          */
 762         skb->protocol = eth->h_proto;
 763
 764         return skb;
 765 }
 766
 767 gro_result_t napi_gro_frags(struct napi_struct *napi)
 768 {
 769         gro_result_t ret;
 770         struct sk_buff *skb = napi_frags_skb(napi);
 771
 772         trace_napi_gro_frags_entry(skb);
 773
 774         ret = napi_frags_finish(napi, skb, dev_gro_receive(napi, skb));
 775         trace_napi_gro_frags_exit(ret);
 776
 777         return ret;
 778 }
 779 EXPORT_SYMBOL(napi_gro_frags);
 780
 781 /* Compute the checksum from gro_offset and return the folded value
 782  * after adding in any pseudo checksum.
 783  */
 784 __sum16 __skb_gro_checksum_complete(struct sk_buff *skb)
 785 {
 786         __wsum wsum;
 787         __sum16 sum;
 788
 789         wsum = skb_checksum(skb, skb_gro_offset(skb), skb_gro_len(skb), 0);
 790
 791         /* NAPI_GRO_CB(skb)->csum holds pseudo checksum */
 792         sum = csum_fold(csum_add(NAPI_GRO_CB(skb)->csum, wsum));
 793         /* See comments in __skb_checksum_complete(). */
 794         if (likely(!sum)) {
 795                 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
 796                     !skb->csum_complete_sw)
 797                         netdev_rx_csum_fault(skb->dev, skb);
 798         }
 799
 800         NAPI_GRO_CB(skb)->csum = wsum;
 801         NAPI_GRO_CB(skb)->csum_valid = 1;
 802
 803         return sum;
 804 }
 805 EXPORT_SYMBOL(__skb_gro_checksum_complete);