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 |= p->vlan_all ^ skb->vlan_all;
 374                 diffs |= skb_metadata_differs(p, skb);
 375                 if (maclen == ETH_HLEN)
 376                         diffs |= compare_ether_header(skb_mac_header(p),
 377                                                       skb_mac_header(skb));
 378                 else if (!diffs)
 379                         diffs = memcmp(skb_mac_header(p),
 380                                        skb_mac_header(skb),
 381                                        maclen);
 382
 383                 /* in most common scenarions 'slow_gro' is 0
 384                  * otherwise we are already on some slower paths
 385                  * either skip all the infrequent tests altogether or
 386                  * avoid trying too hard to skip each of them individually
 387                  */
 388                 if (!diffs && unlikely(skb->slow_gro | p->slow_gro)) {
 389 #if IS_ENABLED(CONFIG_SKB_EXTENSIONS) && IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
 390                         struct tc_skb_ext *skb_ext;
 391                         struct tc_skb_ext *p_ext;
 392 #endif
 393
 394                         diffs |= p->sk != skb->sk;
 395                         diffs |= skb_metadata_dst_cmp(p, skb);
 396                         diffs |= skb_get_nfct(p) ^ skb_get_nfct(skb);
 397
 398 #if IS_ENABLED(CONFIG_SKB_EXTENSIONS) && IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
 399                         skb_ext = skb_ext_find(skb, TC_SKB_EXT);
 400                         p_ext = skb_ext_find(p, TC_SKB_EXT);
 401
 402                         diffs |= (!!p_ext) ^ (!!skb_ext);
 403                         if (!diffs && unlikely(skb_ext))
 404                                 diffs |= p_ext->chain ^ skb_ext->chain;
 405 #endif
 406                 }
 407
 408                 NAPI_GRO_CB(p)->same_flow = !diffs;
 409         }
 410 }
 411
 412 static inline void skb_gro_reset_offset(struct sk_buff *skb, u32 nhoff)
 413 {
 414         const struct skb_shared_info *pinfo = skb_shinfo(skb);
 415         const skb_frag_t *frag0 = &pinfo->frags[0];
 416
 417         NAPI_GRO_CB(skb)->data_offset = 0;
 418         NAPI_GRO_CB(skb)->frag0 = NULL;
 419         NAPI_GRO_CB(skb)->frag0_len = 0;
 420
 421         if (!skb_headlen(skb) && pinfo->nr_frags &&
 422             !PageHighMem(skb_frag_page(frag0)) &&
 423             (!NET_IP_ALIGN || !((skb_frag_off(frag0) + nhoff) & 3))) {
 424                 NAPI_GRO_CB(skb)->frag0 = skb_frag_address(frag0);
 425                 NAPI_GRO_CB(skb)->frag0_len = min_t(unsigned int,
 426                                                     skb_frag_size(frag0),
 427                                                     skb->end - skb->tail);
 428         }
 429 }
 430
 431 static void gro_pull_from_frag0(struct sk_buff *skb, int grow)
 432 {
 433         struct skb_shared_info *pinfo = skb_shinfo(skb);
 434
 435         BUG_ON(skb->end - skb->tail < grow);
 436
 437         memcpy(skb_tail_pointer(skb), NAPI_GRO_CB(skb)->frag0, grow);
 438
 439         skb->data_len -= grow;
 440         skb->tail += grow;
 441
 442         skb_frag_off_add(&pinfo->frags[0], grow);
 443         skb_frag_size_sub(&pinfo->frags[0], grow);
 444
 445         if (unlikely(!skb_frag_size(&pinfo->frags[0]))) {
 446                 skb_frag_unref(skb, 0);
 447                 memmove(pinfo->frags, pinfo->frags + 1,
 448                         --pinfo->nr_frags * sizeof(pinfo->frags[0]));
 449         }
 450 }
 451
 452 static void gro_flush_oldest(struct napi_struct *napi, struct list_head *head)
 453 {
 454         struct sk_buff *oldest;
 455
 456         oldest = list_last_entry(head, struct sk_buff, list);
 457
 458         /* We are called with head length >= MAX_GRO_SKBS, so this is
 459          * impossible.
 460          */
 461         if (WARN_ON_ONCE(!oldest))
 462                 return;
 463
 464         /* Do not adjust napi->gro_hash[].count, caller is adding a new
 465          * SKB to the chain.
 466          */
 467         skb_list_del_init(oldest);
 468         napi_gro_complete(napi, oldest);
 469 }
 470
 471 static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
 472 {
 473         u32 bucket = skb_get_hash_raw(skb) & (GRO_HASH_BUCKETS - 1);
 474         struct gro_list *gro_list = &napi->gro_hash[bucket];
 475         struct list_head *head = &offload_base;
 476         struct packet_offload *ptype;
 477         __be16 type = skb->protocol;
 478         struct sk_buff *pp = NULL;
 479         enum gro_result ret;
 480         int same_flow;
 481         int grow;
 482
 483         if (netif_elide_gro(skb->dev))
 484                 goto normal;
 485
 486         gro_list_prepare(&gro_list->list, skb);
 487
 488         rcu_read_lock();
 489         list_for_each_entry_rcu(ptype, head, list) {
 490                 if (ptype->type == type && ptype->callbacks.gro_receive)
 491                         goto found_ptype;
 492         }
 493         rcu_read_unlock();
 494         goto normal;
 495
 496 found_ptype:
 497         skb_set_network_header(skb, skb_gro_offset(skb));
 498         skb_reset_mac_len(skb);
 499         BUILD_BUG_ON(sizeof_field(struct napi_gro_cb, zeroed) != sizeof(u32));
 500         BUILD_BUG_ON(!IS_ALIGNED(offsetof(struct napi_gro_cb, zeroed),
 501                                         sizeof(u32))); /* Avoid slow unaligned acc */
 502         *(u32 *)&NAPI_GRO_CB(skb)->zeroed = 0;
 503         NAPI_GRO_CB(skb)->flush = skb_has_frag_list(skb);
 504         NAPI_GRO_CB(skb)->is_atomic = 1;
 505         NAPI_GRO_CB(skb)->count = 1;
 506         if (unlikely(skb_is_gso(skb))) {
 507                 NAPI_GRO_CB(skb)->count = skb_shinfo(skb)->gso_segs;
 508                 /* Only support TCP at the moment. */
 509                 if (!skb_is_gso_tcp(skb))
 510                         NAPI_GRO_CB(skb)->flush = 1;
 511         }
 512
 513         /* Setup for GRO checksum validation */
 514         switch (skb->ip_summed) {
 515         case CHECKSUM_COMPLETE:
 516                 NAPI_GRO_CB(skb)->csum = skb->csum;
 517                 NAPI_GRO_CB(skb)->csum_valid = 1;
 518                 break;
 519         case CHECKSUM_UNNECESSARY:
 520                 NAPI_GRO_CB(skb)->csum_cnt = skb->csum_level + 1;
 521                 break;
 522         }
 523
 524         pp = INDIRECT_CALL_INET(ptype->callbacks.gro_receive,
 525                                 ipv6_gro_receive, inet_gro_receive,
 526                                 &gro_list->list, skb);
 527
 528         rcu_read_unlock();
 529
 530         if (PTR_ERR(pp) == -EINPROGRESS) {
 531                 ret = GRO_CONSUMED;
 532                 goto ok;
 533         }
 534
 535         same_flow = NAPI_GRO_CB(skb)->same_flow;
 536         ret = NAPI_GRO_CB(skb)->free ? GRO_MERGED_FREE : GRO_MERGED;
 537
 538         if (pp) {
 539                 skb_list_del_init(pp);
 540                 napi_gro_complete(napi, pp);
 541                 gro_list->count--;
 542         }
 543
 544         if (same_flow)
 545                 goto ok;
 546
 547         if (NAPI_GRO_CB(skb)->flush)
 548                 goto normal;
 549
 550         if (unlikely(gro_list->count >= MAX_GRO_SKBS))
 551                 gro_flush_oldest(napi, &gro_list->list);
 552         else
 553                 gro_list->count++;
 554
 555         NAPI_GRO_CB(skb)->age = jiffies;
 556         NAPI_GRO_CB(skb)->last = skb;
 557         if (!skb_is_gso(skb))
 558                 skb_shinfo(skb)->gso_size = skb_gro_len(skb);
 559         list_add(&skb->list, &gro_list->list);
 560         ret = GRO_HELD;
 561
 562 pull:
 563         grow = skb_gro_offset(skb) - skb_headlen(skb);
 564         if (grow > 0)
 565                 gro_pull_from_frag0(skb, grow);
 566 ok:
 567         if (gro_list->count) {
 568                 if (!test_bit(bucket, &napi->gro_bitmask))
 569                         __set_bit(bucket, &napi->gro_bitmask);
 570         } else if (test_bit(bucket, &napi->gro_bitmask)) {
 571                 __clear_bit(bucket, &napi->gro_bitmask);
 572         }
 573
 574         return ret;
 575
 576 normal:
 577         ret = GRO_NORMAL;
 578         goto pull;
 579 }
 580
 581 struct packet_offload *gro_find_receive_by_type(__be16 type)
 582 {
 583         struct list_head *offload_head = &offload_base;
 584         struct packet_offload *ptype;
 585
 586         list_for_each_entry_rcu(ptype, offload_head, list) {
 587                 if (ptype->type != type || !ptype->callbacks.gro_receive)
 588                         continue;
 589                 return ptype;
 590         }
 591         return NULL;
 592 }
 593 EXPORT_SYMBOL(gro_find_receive_by_type);
 594
 595 struct packet_offload *gro_find_complete_by_type(__be16 type)
 596 {
 597         struct list_head *offload_head = &offload_base;
 598         struct packet_offload *ptype;
 599
 600         list_for_each_entry_rcu(ptype, offload_head, list) {
 601                 if (ptype->type != type || !ptype->callbacks.gro_complete)
 602                         continue;
 603                 return ptype;
 604         }
 605         return NULL;
 606 }
 607 EXPORT_SYMBOL(gro_find_complete_by_type);
 608
 609 static gro_result_t napi_skb_finish(struct napi_struct *napi,
 610                                     struct sk_buff *skb,
 611                                     gro_result_t ret)
 612 {
 613         switch (ret) {
 614         case GRO_NORMAL:
 615                 gro_normal_one(napi, skb, 1);
 616                 break;
 617
 618         case GRO_MERGED_FREE:
 619                 if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
 620                         napi_skb_free_stolen_head(skb);
 621                 else if (skb->fclone != SKB_FCLONE_UNAVAILABLE)
 622                         __kfree_skb(skb);
 623                 else
 624                         __kfree_skb_defer(skb);
 625                 break;
 626
 627         case GRO_HELD:
 628         case GRO_MERGED:
 629         case GRO_CONSUMED:
 630                 break;
 631         }
 632
 633         return ret;
 634 }
 635
 636 gro_result_t napi_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
 637 {
 638         gro_result_t ret;
 639
 640         skb_mark_napi_id(skb, napi);
 641         trace_napi_gro_receive_entry(skb);
 642
 643         skb_gro_reset_offset(skb, 0);
 644
 645         ret = napi_skb_finish(napi, skb, dev_gro_receive(napi, skb));
 646         trace_napi_gro_receive_exit(ret);
 647
 648         return ret;
 649 }
 650 EXPORT_SYMBOL(napi_gro_receive);
 651
 652 static void napi_reuse_skb(struct napi_struct *napi, struct sk_buff *skb)
 653 {
 654         if (unlikely(skb->pfmemalloc)) {
 655                 consume_skb(skb);
 656                 return;
 657         }
 658         __skb_pull(skb, skb_headlen(skb));
 659         /* restore the reserve we had after netdev_alloc_skb_ip_align() */
 660         skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN - skb_headroom(skb));
 661         __vlan_hwaccel_clear_tag(skb);
 662         skb->dev = napi->dev;
 663         skb->skb_iif = 0;
 664
 665         /* eth_type_trans() assumes pkt_type is PACKET_HOST */
 666         skb->pkt_type = PACKET_HOST;
 667
 668         skb->encapsulation = 0;
 669         skb_shinfo(skb)->gso_type = 0;
 670         skb_shinfo(skb)->gso_size = 0;
 671         if (unlikely(skb->slow_gro)) {
 672                 skb_orphan(skb);
 673                 skb_ext_reset(skb);
 674                 nf_reset_ct(skb);
 675                 skb->slow_gro = 0;
 676         }
 677
 678         napi->skb = skb;
 679 }
 680
 681 struct sk_buff *napi_get_frags(struct napi_struct *napi)
 682 {
 683         struct sk_buff *skb = napi->skb;
 684
 685         if (!skb) {
 686                 skb = napi_alloc_skb(napi, GRO_MAX_HEAD);
 687                 if (skb) {
 688                         napi->skb = skb;
 689                         skb_mark_napi_id(skb, napi);
 690                 }
 691         }
 692         return skb;
 693 }
 694 EXPORT_SYMBOL(napi_get_frags);
 695
 696 static gro_result_t napi_frags_finish(struct napi_struct *napi,
 697                                       struct sk_buff *skb,
 698                                       gro_result_t ret)
 699 {
 700         switch (ret) {
 701         case GRO_NORMAL:
 702         case GRO_HELD:
 703                 __skb_push(skb, ETH_HLEN);
 704                 skb->protocol = eth_type_trans(skb, skb->dev);
 705                 if (ret == GRO_NORMAL)
 706                         gro_normal_one(napi, skb, 1);
 707                 break;
 708
 709         case GRO_MERGED_FREE:
 710                 if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
 711                         napi_skb_free_stolen_head(skb);
 712                 else
 713                         napi_reuse_skb(napi, skb);
 714                 break;
 715
 716         case GRO_MERGED:
 717         case GRO_CONSUMED:
 718                 break;
 719         }
 720
 721         return ret;
 722 }
 723
 724 /* Upper GRO stack assumes network header starts at gro_offset=0
 725  * Drivers could call both napi_gro_frags() and napi_gro_receive()
 726  * We copy ethernet header into skb->data to have a common layout.
 727  */
 728 static struct sk_buff *napi_frags_skb(struct napi_struct *napi)
 729 {
 730         struct sk_buff *skb = napi->skb;
 731         const struct ethhdr *eth;
 732         unsigned int hlen = sizeof(*eth);
 733
 734         napi->skb = NULL;
 735
 736         skb_reset_mac_header(skb);
 737         skb_gro_reset_offset(skb, hlen);
 738
 739         if (unlikely(skb_gro_header_hard(skb, hlen))) {
 740                 eth = skb_gro_header_slow(skb, hlen, 0);
 741                 if (unlikely(!eth)) {
 742                         net_warn_ratelimited("%s: dropping impossible skb from %s\n",
 743                                              __func__, napi->dev->name);
 744                         napi_reuse_skb(napi, skb);
 745                         return NULL;
 746                 }
 747         } else {
 748                 eth = (const struct ethhdr *)skb->data;
 749                 gro_pull_from_frag0(skb, hlen);
 750                 NAPI_GRO_CB(skb)->frag0 += hlen;
 751                 NAPI_GRO_CB(skb)->frag0_len -= hlen;
 752         }
 753         __skb_pull(skb, hlen);
 754
 755         /*
 756          * This works because the only protocols we care about don't require
 757          * special handling.
 758          * We'll fix it up properly in napi_frags_finish()
 759          */
 760         skb->protocol = eth->h_proto;
 761
 762         return skb;
 763 }
 764
 765 gro_result_t napi_gro_frags(struct napi_struct *napi)
 766 {
 767         gro_result_t ret;
 768         struct sk_buff *skb = napi_frags_skb(napi);
 769
 770         trace_napi_gro_frags_entry(skb);
 771
 772         ret = napi_frags_finish(napi, skb, dev_gro_receive(napi, skb));
 773         trace_napi_gro_frags_exit(ret);
 774
 775         return ret;
 776 }
 777 EXPORT_SYMBOL(napi_gro_frags);
 778
 779 /* Compute the checksum from gro_offset and return the folded value
 780  * after adding in any pseudo checksum.
 781  */
 782 __sum16 __skb_gro_checksum_complete(struct sk_buff *skb)
 783 {
 784         __wsum wsum;
 785         __sum16 sum;
 786
 787         wsum = skb_checksum(skb, skb_gro_offset(skb), skb_gro_len(skb), 0);
 788
 789         /* NAPI_GRO_CB(skb)->csum holds pseudo checksum */
 790         sum = csum_fold(csum_add(NAPI_GRO_CB(skb)->csum, wsum));
 791         /* See comments in __skb_checksum_complete(). */
 792         if (likely(!sum)) {
 793                 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
 794                     !skb->csum_complete_sw)
 795                         netdev_rx_csum_fault(skb->dev, skb);
 796         }
 797
 798         NAPI_GRO_CB(skb)->csum = wsum;
 799         NAPI_GRO_CB(skb)->csum_valid = 1;
 800
 801         return sum;
 802 }
 803 EXPORT_SYMBOL(__skb_gro_checksum_complete);