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         /* Do not splice page pool based packets w/ non-page pool
 166          * packets. This can result in reference count issues as page
 167          * pool pages will not decrement the reference count and will
 168          * instead be immediately returned to the pool or have frag
 169          * count decremented.
 170          */
 171         if (p->pp_recycle != skb->pp_recycle)
 172                 return -ETOOMANYREFS;
 173
 174         /* pairs with WRITE_ONCE() in netif_set_gro_max_size() */
 175         gro_max_size = READ_ONCE(p->dev->gro_max_size);
 176
 177         if (unlikely(p->len + len >= gro_max_size || NAPI_GRO_CB(skb)->flush))
 178                 return -E2BIG;
 179
 180         if (unlikely(p->len + len >= GRO_LEGACY_MAX_SIZE)) {
 181                 if (p->protocol != htons(ETH_P_IPV6) ||
 182                     skb_headroom(p) < sizeof(struct hop_jumbo_hdr) ||
 183                     ipv6_hdr(p)->nexthdr != IPPROTO_TCP ||
 184                     p->encapsulation)
 185                         return -E2BIG;
 186         }
 187
 188         segs = NAPI_GRO_CB(skb)->count;
 189         lp = NAPI_GRO_CB(p)->last;
 190         pinfo = skb_shinfo(lp);
 191
 192         if (headlen <= offset) {
 193                 skb_frag_t *frag;
 194                 skb_frag_t *frag2;
 195                 int i = skbinfo->nr_frags;
 196                 int nr_frags = pinfo->nr_frags + i;
 197
 198                 if (nr_frags > MAX_SKB_FRAGS)
 199                         goto merge;
 200
 201                 offset -= headlen;
 202                 pinfo->nr_frags = nr_frags;
 203                 skbinfo->nr_frags = 0;
 204
 205                 frag = pinfo->frags + nr_frags;
 206                 frag2 = skbinfo->frags + i;
 207                 do {
 208                         *--frag = *--frag2;
 209                 } while (--i);
 210
 211                 skb_frag_off_add(frag, offset);
 212                 skb_frag_size_sub(frag, offset);
 213
 214                 /* all fragments truesize : remove (head size + sk_buff) */
 215                 new_truesize = SKB_TRUESIZE(skb_end_offset(skb));
 216                 delta_truesize = skb->truesize - new_truesize;
 217
 218                 skb->truesize = new_truesize;
 219                 skb->len -= skb->data_len;
 220                 skb->data_len = 0;
 221
 222                 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE;
 223                 goto done;
 224         } else if (skb->head_frag) {
 225                 int nr_frags = pinfo->nr_frags;
 226                 skb_frag_t *frag = pinfo->frags + nr_frags;
 227                 struct page *page = virt_to_head_page(skb->head);
 228                 unsigned int first_size = headlen - offset;
 229                 unsigned int first_offset;
 230
 231                 if (nr_frags + 1 + skbinfo->nr_frags > MAX_SKB_FRAGS)
 232                         goto merge;
 233
 234                 first_offset = skb->data -
 235                                (unsigned char *)page_address(page) +
 236                                offset;
 237
 238                 pinfo->nr_frags = nr_frags + 1 + skbinfo->nr_frags;
 239
 240                 __skb_frag_set_page(frag, page);
 241                 skb_frag_off_set(frag, first_offset);
 242                 skb_frag_size_set(frag, first_size);
 243
 244                 memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags);
 245                 /* We dont need to clear skbinfo->nr_frags here */
 246
 247                 new_truesize = SKB_DATA_ALIGN(sizeof(struct sk_buff));
 248                 delta_truesize = skb->truesize - new_truesize;
 249                 skb->truesize = new_truesize;
 250                 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD;
 251                 goto done;
 252         }
 253
 254 merge:
 255         /* sk owenrship - if any - completely transferred to the aggregated packet */
 256         skb->destructor = NULL;
 257         delta_truesize = skb->truesize;
 258         if (offset > headlen) {
 259                 unsigned int eat = offset - headlen;
 260
 261                 skb_frag_off_add(&skbinfo->frags[0], eat);
 262                 skb_frag_size_sub(&skbinfo->frags[0], eat);
 263                 skb->data_len -= eat;
 264                 skb->len -= eat;
 265                 offset = headlen;
 266         }
 267
 268         __skb_pull(skb, offset);
 269
 270         if (NAPI_GRO_CB(p)->last == p)
 271                 skb_shinfo(p)->frag_list = skb;
 272         else
 273                 NAPI_GRO_CB(p)->last->next = skb;
 274         NAPI_GRO_CB(p)->last = skb;
 275         __skb_header_release(skb);
 276         lp = p;
 277
 278 done:
 279         NAPI_GRO_CB(p)->count += segs;
 280         p->data_len += len;
 281         p->truesize += delta_truesize;
 282         p->len += len;
 283         if (lp != p) {
 284                 lp->data_len += len;
 285                 lp->truesize += delta_truesize;
 286                 lp->len += len;
 287         }
 288         NAPI_GRO_CB(skb)->same_flow = 1;
 289         return 0;
 290 }
 291
 292
 293 static void napi_gro_complete(struct napi_struct *napi, struct sk_buff *skb)
 294 {
 295         struct packet_offload *ptype;
 296         __be16 type = skb->protocol;
 297         struct list_head *head = &offload_base;
 298         int err = -ENOENT;
 299
 300         BUILD_BUG_ON(sizeof(struct napi_gro_cb) > sizeof(skb->cb));
 301
 302         if (NAPI_GRO_CB(skb)->count == 1) {
 303                 skb_shinfo(skb)->gso_size = 0;
 304                 goto out;
 305         }
 306
 307         rcu_read_lock();
 308         list_for_each_entry_rcu(ptype, head, list) {
 309                 if (ptype->type != type || !ptype->callbacks.gro_complete)
 310                         continue;
 311
 312                 err = INDIRECT_CALL_INET(ptype->callbacks.gro_complete,
 313                                          ipv6_gro_complete, inet_gro_complete,
 314                                          skb, 0);
 315                 break;
 316         }
 317         rcu_read_unlock();
 318
 319         if (err) {
 320                 WARN_ON(&ptype->list == head);
 321                 kfree_skb(skb);
 322                 return;
 323         }
 324
 325 out:
 326         gro_normal_one(napi, skb, NAPI_GRO_CB(skb)->count);
 327 }
 328
 329 static void __napi_gro_flush_chain(struct napi_struct *napi, u32 index,
 330                                    bool flush_old)
 331 {
 332         struct list_head *head = &napi->gro_hash[index].list;
 333         struct sk_buff *skb, *p;
 334
 335         list_for_each_entry_safe_reverse(skb, p, head, list) {
 336                 if (flush_old && NAPI_GRO_CB(skb)->age == jiffies)
 337                         return;
 338                 skb_list_del_init(skb);
 339                 napi_gro_complete(napi, skb);
 340                 napi->gro_hash[index].count--;
 341         }
 342
 343         if (!napi->gro_hash[index].count)
 344                 __clear_bit(index, &napi->gro_bitmask);
 345 }
 346
 347 /* napi->gro_hash[].list contains packets ordered by age.
 348  * youngest packets at the head of it.
 349  * Complete skbs in reverse order to reduce latencies.
 350  */
 351 void napi_gro_flush(struct napi_struct *napi, bool flush_old)
 352 {
 353         unsigned long bitmask = napi->gro_bitmask;
 354         unsigned int i, base = ~0U;
 355
 356         while ((i = ffs(bitmask)) != 0) {
 357                 bitmask >>= i;
 358                 base += i;
 359                 __napi_gro_flush_chain(napi, base, flush_old);
 360         }
 361 }
 362 EXPORT_SYMBOL(napi_gro_flush);
 363
 364 static void gro_list_prepare(const struct list_head *head,
 365                              const struct sk_buff *skb)
 366 {
 367         unsigned int maclen = skb->dev->hard_header_len;
 368         u32 hash = skb_get_hash_raw(skb);
 369         struct sk_buff *p;
 370
 371         list_for_each_entry(p, head, list) {
 372                 unsigned long diffs;
 373
 374                 NAPI_GRO_CB(p)->flush = 0;
 375
 376                 if (hash != skb_get_hash_raw(p)) {
 377                         NAPI_GRO_CB(p)->same_flow = 0;
 378                         continue;
 379                 }
 380
 381                 diffs = (unsigned long)p->dev ^ (unsigned long)skb->dev;
 382                 diffs |= skb_vlan_tag_present(p) ^ skb_vlan_tag_present(skb);
 383                 if (skb_vlan_tag_present(p))
 384                         diffs |= skb_vlan_tag_get(p) ^ skb_vlan_tag_get(skb);
 385                 diffs |= skb_metadata_differs(p, skb);
 386                 if (maclen == ETH_HLEN)
 387                         diffs |= compare_ether_header(skb_mac_header(p),
 388                                                       skb_mac_header(skb));
 389                 else if (!diffs)
 390                         diffs = memcmp(skb_mac_header(p),
 391                                        skb_mac_header(skb),
 392                                        maclen);
 393
 394                 /* in most common scenarions 'slow_gro' is 0
 395                  * otherwise we are already on some slower paths
 396                  * either skip all the infrequent tests altogether or
 397                  * avoid trying too hard to skip each of them individually
 398                  */
 399                 if (!diffs && unlikely(skb->slow_gro | p->slow_gro)) {
 400 #if IS_ENABLED(CONFIG_SKB_EXTENSIONS) && IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
 401                         struct tc_skb_ext *skb_ext;
 402                         struct tc_skb_ext *p_ext;
 403 #endif
 404
 405                         diffs |= p->sk != skb->sk;
 406                         diffs |= skb_metadata_dst_cmp(p, skb);
 407                         diffs |= skb_get_nfct(p) ^ skb_get_nfct(skb);
 408
 409 #if IS_ENABLED(CONFIG_SKB_EXTENSIONS) && IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
 410                         skb_ext = skb_ext_find(skb, TC_SKB_EXT);
 411                         p_ext = skb_ext_find(p, TC_SKB_EXT);
 412
 413                         diffs |= (!!p_ext) ^ (!!skb_ext);
 414                         if (!diffs && unlikely(skb_ext))
 415                                 diffs |= p_ext->chain ^ skb_ext->chain;
 416 #endif
 417                 }
 418
 419                 NAPI_GRO_CB(p)->same_flow = !diffs;
 420         }
 421 }
 422
 423 static inline void skb_gro_reset_offset(struct sk_buff *skb, u32 nhoff)
 424 {
 425         const struct skb_shared_info *pinfo = skb_shinfo(skb);
 426         const skb_frag_t *frag0 = &pinfo->frags[0];
 427
 428         NAPI_GRO_CB(skb)->data_offset = 0;
 429         NAPI_GRO_CB(skb)->frag0 = NULL;
 430         NAPI_GRO_CB(skb)->frag0_len = 0;
 431
 432         if (!skb_headlen(skb) && pinfo->nr_frags &&
 433             !PageHighMem(skb_frag_page(frag0)) &&
 434             (!NET_IP_ALIGN || !((skb_frag_off(frag0) + nhoff) & 3))) {
 435                 NAPI_GRO_CB(skb)->frag0 = skb_frag_address(frag0);
 436                 NAPI_GRO_CB(skb)->frag0_len = min_t(unsigned int,
 437                                                     skb_frag_size(frag0),
 438                                                     skb->end - skb->tail);
 439         }
 440 }
 441
 442 static void gro_pull_from_frag0(struct sk_buff *skb, int grow)
 443 {
 444         struct skb_shared_info *pinfo = skb_shinfo(skb);
 445
 446         BUG_ON(skb->end - skb->tail < grow);
 447
 448         memcpy(skb_tail_pointer(skb), NAPI_GRO_CB(skb)->frag0, grow);
 449
 450         skb->data_len -= grow;
 451         skb->tail += grow;
 452
 453         skb_frag_off_add(&pinfo->frags[0], grow);
 454         skb_frag_size_sub(&pinfo->frags[0], grow);
 455
 456         if (unlikely(!skb_frag_size(&pinfo->frags[0]))) {
 457                 skb_frag_unref(skb, 0);
 458                 memmove(pinfo->frags, pinfo->frags + 1,
 459                         --pinfo->nr_frags * sizeof(pinfo->frags[0]));
 460         }
 461 }
 462
 463 static void gro_flush_oldest(struct napi_struct *napi, struct list_head *head)
 464 {
 465         struct sk_buff *oldest;
 466
 467         oldest = list_last_entry(head, struct sk_buff, list);
 468
 469         /* We are called with head length >= MAX_GRO_SKBS, so this is
 470          * impossible.
 471          */
 472         if (WARN_ON_ONCE(!oldest))
 473                 return;
 474
 475         /* Do not adjust napi->gro_hash[].count, caller is adding a new
 476          * SKB to the chain.
 477          */
 478         skb_list_del_init(oldest);
 479         napi_gro_complete(napi, oldest);
 480 }
 481
 482 static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
 483 {
 484         u32 bucket = skb_get_hash_raw(skb) & (GRO_HASH_BUCKETS - 1);
 485         struct gro_list *gro_list = &napi->gro_hash[bucket];
 486         struct list_head *head = &offload_base;
 487         struct packet_offload *ptype;
 488         __be16 type = skb->protocol;
 489         struct sk_buff *pp = NULL;
 490         enum gro_result ret;
 491         int same_flow;
 492         int grow;
 493
 494         if (netif_elide_gro(skb->dev))
 495                 goto normal;
 496
 497         gro_list_prepare(&gro_list->list, skb);
 498
 499         rcu_read_lock();
 500         list_for_each_entry_rcu(ptype, head, list) {
 501                 if (ptype->type == type && ptype->callbacks.gro_receive)
 502                         goto found_ptype;
 503         }
 504         rcu_read_unlock();
 505         goto normal;
 506
 507 found_ptype:
 508         skb_set_network_header(skb, skb_gro_offset(skb));
 509         skb_reset_mac_len(skb);
 510         BUILD_BUG_ON(sizeof_field(struct napi_gro_cb, zeroed) != sizeof(u32));
 511         BUILD_BUG_ON(!IS_ALIGNED(offsetof(struct napi_gro_cb, zeroed),
 512                                         sizeof(u32))); /* Avoid slow unaligned acc */
 513         *(u32 *)&NAPI_GRO_CB(skb)->zeroed = 0;
 514         NAPI_GRO_CB(skb)->flush = skb_has_frag_list(skb);
 515         NAPI_GRO_CB(skb)->is_atomic = 1;
 516         NAPI_GRO_CB(skb)->count = 1;
 517         if (unlikely(skb_is_gso(skb))) {
 518                 NAPI_GRO_CB(skb)->count = skb_shinfo(skb)->gso_segs;
 519                 /* Only support TCP and non DODGY users. */
 520                 if (!skb_is_gso_tcp(skb) ||
 521                     (skb_shinfo(skb)->gso_type & SKB_GSO_DODGY))
 522                         NAPI_GRO_CB(skb)->flush = 1;
 523         }
 524
 525         /* Setup for GRO checksum validation */
 526         switch (skb->ip_summed) {
 527         case CHECKSUM_COMPLETE:
 528                 NAPI_GRO_CB(skb)->csum = skb->csum;
 529                 NAPI_GRO_CB(skb)->csum_valid = 1;
 530                 break;
 531         case CHECKSUM_UNNECESSARY:
 532                 NAPI_GRO_CB(skb)->csum_cnt = skb->csum_level + 1;
 533                 break;
 534         }
 535
 536         pp = INDIRECT_CALL_INET(ptype->callbacks.gro_receive,
 537                                 ipv6_gro_receive, inet_gro_receive,
 538                                 &gro_list->list, skb);
 539
 540         rcu_read_unlock();
 541
 542         if (PTR_ERR(pp) == -EINPROGRESS) {
 543                 ret = GRO_CONSUMED;
 544                 goto ok;
 545         }
 546
 547         same_flow = NAPI_GRO_CB(skb)->same_flow;
 548         ret = NAPI_GRO_CB(skb)->free ? GRO_MERGED_FREE : GRO_MERGED;
 549
 550         if (pp) {
 551                 skb_list_del_init(pp);
 552                 napi_gro_complete(napi, pp);
 553                 gro_list->count--;
 554         }
 555
 556         if (same_flow)
 557                 goto ok;
 558
 559         if (NAPI_GRO_CB(skb)->flush)
 560                 goto normal;
 561
 562         if (unlikely(gro_list->count >= MAX_GRO_SKBS))
 563                 gro_flush_oldest(napi, &gro_list->list);
 564         else
 565                 gro_list->count++;
 566
 567         NAPI_GRO_CB(skb)->age = jiffies;
 568         NAPI_GRO_CB(skb)->last = skb;
 569         if (!skb_is_gso(skb))
 570                 skb_shinfo(skb)->gso_size = skb_gro_len(skb);
 571         list_add(&skb->list, &gro_list->list);
 572         ret = GRO_HELD;
 573
 574 pull:
 575         grow = skb_gro_offset(skb) - skb_headlen(skb);
 576         if (grow > 0)
 577                 gro_pull_from_frag0(skb, grow);
 578 ok:
 579         if (gro_list->count) {
 580                 if (!test_bit(bucket, &napi->gro_bitmask))
 581                         __set_bit(bucket, &napi->gro_bitmask);
 582         } else if (test_bit(bucket, &napi->gro_bitmask)) {
 583                 __clear_bit(bucket, &napi->gro_bitmask);
 584         }
 585
 586         return ret;
 587
 588 normal:
 589         ret = GRO_NORMAL;
 590         goto pull;
 591 }
 592
 593 struct packet_offload *gro_find_receive_by_type(__be16 type)
 594 {
 595         struct list_head *offload_head = &offload_base;
 596         struct packet_offload *ptype;
 597
 598         list_for_each_entry_rcu(ptype, offload_head, list) {
 599                 if (ptype->type != type || !ptype->callbacks.gro_receive)
 600                         continue;
 601                 return ptype;
 602         }
 603         return NULL;
 604 }
 605 EXPORT_SYMBOL(gro_find_receive_by_type);
 606
 607 struct packet_offload *gro_find_complete_by_type(__be16 type)
 608 {
 609         struct list_head *offload_head = &offload_base;
 610         struct packet_offload *ptype;
 611
 612         list_for_each_entry_rcu(ptype, offload_head, list) {
 613                 if (ptype->type != type || !ptype->callbacks.gro_complete)
 614                         continue;
 615                 return ptype;
 616         }
 617         return NULL;
 618 }
 619 EXPORT_SYMBOL(gro_find_complete_by_type);
 620
 621 static gro_result_t napi_skb_finish(struct napi_struct *napi,
 622                                     struct sk_buff *skb,
 623                                     gro_result_t ret)
 624 {
 625         switch (ret) {
 626         case GRO_NORMAL:
 627                 gro_normal_one(napi, skb, 1);
 628                 break;
 629
 630         case GRO_MERGED_FREE:
 631                 if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
 632                         napi_skb_free_stolen_head(skb);
 633                 else if (skb->fclone != SKB_FCLONE_UNAVAILABLE)
 634                         __kfree_skb(skb);
 635                 else
 636                         __kfree_skb_defer(skb);
 637                 break;
 638
 639         case GRO_HELD:
 640         case GRO_MERGED:
 641         case GRO_CONSUMED:
 642                 break;
 643         }
 644
 645         return ret;
 646 }
 647
 648 gro_result_t napi_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
 649 {
 650         gro_result_t ret;
 651
 652         skb_mark_napi_id(skb, napi);
 653         trace_napi_gro_receive_entry(skb);
 654
 655         skb_gro_reset_offset(skb, 0);
 656
 657         ret = napi_skb_finish(napi, skb, dev_gro_receive(napi, skb));
 658         trace_napi_gro_receive_exit(ret);
 659
 660         return ret;
 661 }
 662 EXPORT_SYMBOL(napi_gro_receive);
 663
 664 static void napi_reuse_skb(struct napi_struct *napi, struct sk_buff *skb)
 665 {
 666         if (unlikely(skb->pfmemalloc)) {
 667                 consume_skb(skb);
 668                 return;
 669         }
 670         __skb_pull(skb, skb_headlen(skb));
 671         /* restore the reserve we had after netdev_alloc_skb_ip_align() */
 672         skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN - skb_headroom(skb));
 673         __vlan_hwaccel_clear_tag(skb);
 674         skb->dev = napi->dev;
 675         skb->skb_iif = 0;
 676
 677         /* eth_type_trans() assumes pkt_type is PACKET_HOST */
 678         skb->pkt_type = PACKET_HOST;
 679
 680         skb->encapsulation = 0;
 681         skb_shinfo(skb)->gso_type = 0;
 682         skb_shinfo(skb)->gso_size = 0;
 683         if (unlikely(skb->slow_gro)) {
 684                 skb_orphan(skb);
 685                 skb_ext_reset(skb);
 686                 nf_reset_ct(skb);
 687                 skb->slow_gro = 0;
 688         }
 689
 690         napi->skb = skb;
 691 }
 692
 693 struct sk_buff *napi_get_frags(struct napi_struct *napi)
 694 {
 695         struct sk_buff *skb = napi->skb;
 696
 697         if (!skb) {
 698                 skb = napi_alloc_skb(napi, GRO_MAX_HEAD);
 699                 if (skb) {
 700                         napi->skb = skb;
 701                         skb_mark_napi_id(skb, napi);
 702                 }
 703         }
 704         return skb;
 705 }
 706 EXPORT_SYMBOL(napi_get_frags);
 707
 708 static gro_result_t napi_frags_finish(struct napi_struct *napi,
 709                                       struct sk_buff *skb,
 710                                       gro_result_t ret)
 711 {
 712         switch (ret) {
 713         case GRO_NORMAL:
 714         case GRO_HELD:
 715                 __skb_push(skb, ETH_HLEN);
 716                 skb->protocol = eth_type_trans(skb, skb->dev);
 717                 if (ret == GRO_NORMAL)
 718                         gro_normal_one(napi, skb, 1);
 719                 break;
 720
 721         case GRO_MERGED_FREE:
 722                 if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
 723                         napi_skb_free_stolen_head(skb);
 724                 else
 725                         napi_reuse_skb(napi, skb);
 726                 break;
 727
 728         case GRO_MERGED:
 729         case GRO_CONSUMED:
 730                 break;
 731         }
 732
 733         return ret;
 734 }
 735
 736 /* Upper GRO stack assumes network header starts at gro_offset=0
 737  * Drivers could call both napi_gro_frags() and napi_gro_receive()
 738  * We copy ethernet header into skb->data to have a common layout.
 739  */
 740 static struct sk_buff *napi_frags_skb(struct napi_struct *napi)
 741 {
 742         struct sk_buff *skb = napi->skb;
 743         const struct ethhdr *eth;
 744         unsigned int hlen = sizeof(*eth);
 745
 746         napi->skb = NULL;
 747
 748         skb_reset_mac_header(skb);
 749         skb_gro_reset_offset(skb, hlen);
 750
 751         if (unlikely(skb_gro_header_hard(skb, hlen))) {
 752                 eth = skb_gro_header_slow(skb, hlen, 0);
 753                 if (unlikely(!eth)) {
 754                         net_warn_ratelimited("%s: dropping impossible skb from %s\n",
 755                                              __func__, napi->dev->name);
 756                         napi_reuse_skb(napi, skb);
 757                         return NULL;
 758                 }
 759         } else {
 760                 eth = (const struct ethhdr *)skb->data;
 761                 gro_pull_from_frag0(skb, hlen);
 762                 NAPI_GRO_CB(skb)->frag0 += hlen;
 763                 NAPI_GRO_CB(skb)->frag0_len -= hlen;
 764         }
 765         __skb_pull(skb, hlen);
 766
 767         /*
 768          * This works because the only protocols we care about don't require
 769          * special handling.
 770          * We'll fix it up properly in napi_frags_finish()
 771          */
 772         skb->protocol = eth->h_proto;
 773
 774         return skb;
 775 }
 776
 777 gro_result_t napi_gro_frags(struct napi_struct *napi)
 778 {
 779         gro_result_t ret;
 780         struct sk_buff *skb = napi_frags_skb(napi);
 781
 782         trace_napi_gro_frags_entry(skb);
 783
 784         ret = napi_frags_finish(napi, skb, dev_gro_receive(napi, skb));
 785         trace_napi_gro_frags_exit(ret);
 786
 787         return ret;
 788 }
 789 EXPORT_SYMBOL(napi_gro_frags);
 790
 791 /* Compute the checksum from gro_offset and return the folded value
 792  * after adding in any pseudo checksum.
 793  */
 794 __sum16 __skb_gro_checksum_complete(struct sk_buff *skb)
 795 {
 796         __wsum wsum;
 797         __sum16 sum;
 798
 799         wsum = skb_checksum(skb, skb_gro_offset(skb), skb_gro_len(skb), 0);
 800
 801         /* NAPI_GRO_CB(skb)->csum holds pseudo checksum */
 802         sum = csum_fold(csum_add(NAPI_GRO_CB(skb)->csum, wsum));
 803         /* See comments in __skb_checksum_complete(). */
 804         if (likely(!sum)) {
 805                 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
 806                     !skb->csum_complete_sw)
 807                         netdev_rx_csum_fault(skb->dev, skb);
 808         }
 809
 810         NAPI_GRO_CB(skb)->csum = wsum;
 811         NAPI_GRO_CB(skb)->csum_valid = 1;
 812
 813         return sum;
 814 }
 815 EXPORT_SYMBOL(__skb_gro_checksum_complete);